Skip to main content

CAR-T cells and BiTEs in solid tumors: challenges and perspectives


Chimeric antigen receptor (CAR)-modified T cells and BiTEs are both immunotherapies which redirect T cell specificity against a tumor-specific antigen through the use of antibody fragments. They demonstrated remarkable efficacy in B cell hematologic malignancies, thus paving the way for their development in solid tumors. Nonetheless, the use of such new drugs to treat solid tumors is not straightforward. So far, the results from early phase clinical trials are not as impressive as expected but many improvements are under way. In this review we present an overview of the clinical development of CAR-T cells and BiTEs targeting the main antigens expressed by solid tumors. We emphasize the most frequent hurdles encountered by either CAR-T cells or BiTEs, or both, and summarize the strategies that have been proposed to overcome these obstacles.


The recent years have seen the revolution of immunotherapy enter the clinic. This new class of agents uses different therapeutic approaches, most of which focus are based on T cells. While immune checkpoint inhibitors (ICI) have been approved in a wide range of solid tumors, other immunotherapies such as chimeric antigen receptor (CAR)-T cells and T cell redirecting bispecific T cell Engager (BiTE) have exclusively been approved in hematologic malignancies and are yet poorly studied in solid tumors [1,2,3]. Immune therapies which have been approved in hematologic malignancies target “ideal” antigens, namely CD19, CD20 and BCMA, for several reasons: these antigens are present on all tumors cells; the normal cells which also express these antigens are dispensable and can be eliminated without excessive “on-target, off-tumor” toxicity; these antigens are expressed on the surface and as such are easily accessible without the need for presentation through the major histocompatibility complex (MHC). Because of impressive results observed with BiTEs and CAR-T cells in hematologic malignancies, many researchers, both academic and industrial, are trying to expand these therapies to the field of solid tumors. In this review, we present the specificities related to the development of CAR-T cells and BiTEs in solid tumors, illustrate the main challenges encountered in this development, and highlight approaches to overcome these obstacles.

CAR-T cells and BiTEs: overview of their development in solid tumors

CAR-T cells and BiTEs’ mechanisms of action rely on redirecting T cell specificity against a tumor antigen through the use of antibody fragments. CAR-T cells are genetically engineered T cells (either autologous or allogeneic) that express a chimeric antigen receptor (CAR). Indeed, the CAR is composed of an extracellular single-chain variable fragment (scFv), “antibody-like” antigen-binding domain, which recognizes a tumor-specific antigen in a MHC independent manner, and intracellular signaling domains, which mimic T cell receptor (TCR) activation [4]. Adoptive cell therapies (ACT) also encompass ex vivo expansion and infusion of tumor-infiltrating lymphocytes (TILs) [5] and genetic redirection of non-therapeutic endogenous lymphocytes with a TCR which recognizes a tumor-specific antigen presented through the MHC [6]. BiTEs are recombinant proteins made of two scFv from two different antibodies, one targeting a tumor-specific antigen and the other targeting the effector T cell (mostly CD3). Thus, endogenous T cells are recruited at the tumor site and redirected to kill cancer cells in vivo [7].

Main characteristics and differences between CAR-T cells and BiTEs are summarized in Table 1. For both types of therapies, the first critical step is the selection of a tumor-specific antigen. The most frequently targeted antigens currently used for the development of these therapies in solid tumors are summarized in Table 2.

Table 1 Comparison of the main characteristics of CAR-T cells and BiTEs
Table 2 Most frequently targeted antigens, and clinical examples of application

One of the major limitations of antigen selection in solid tumors is that some low-level expression is often found in normal tissue exposing the patient to a risk of “on-target, off-tumor” toxicity. This was for example the explanation for one fatal case of early development of HER2-targeting CAR-T cells, where HER2 expression on normal lung epithelial cells was deemed responsible for cytokine release [8]. Furthermore, some antigens are restricted to some tumor types, while other have a broader spectrum across various tumors. Thus, solid tumors often require prior screening to ensure that the target is expressed.

Overall, both BiTEs and CAR-T cells have shown evidence of activity in solid tumors, but these results still need to be improved before entering clinical practice. Current evidence does not support one strategy over the other in solid tumors.

Current challenges with T cell directed therapies in solid tumors

A recent systematic review compared the results of CAR-T cells in hematologic versus solid tumors [9]. The pooled response rate was 71% in hematological malignancies versus 29% in solid tumors. This review might still overestimate the efficacy because some negative trials may not be reported. However, this review confirms that these therapies might be efficient in solid tumors, although responses seem to be more difficult to achieve compared to hematologic malignancies. The different challenges limiting the efficacy of T cell directed therapies in solid tumors are presented in Fig. 1a.

Fig. 1
figure 1

Schematic representation of a the challenges encountered by CAR-T cells and BiTEs for their development in solid tumors and b some solutions proposed to overcome these challenges. Ag: antigen, Ab: antibody, ICI: immune checkpoint inhibitors

Challenges faced by both CAR-T cells and BiTEs

Tumor antigen specificity

As previously discussed, many tumor antigens found in solid tumors lack perfect specificity and are often found at low levels in normal tissue. An elegant demonstration of “on-target, off-tumor” toxicity was the development of CAR-T cells targeting carboxy-anhydrase-IX (CA IX) [10]. CA IX is expressed by many renal cell carcinomas, but low expression can also be found in normal tissue, including bile duct. In the phase 1 trial of CAR-T cells targeting CA IX, Lamers et al.reported frequent high-grade liver toxicities. They subsequently administered CA IX antibodies before CAR-T cell infusion which prevented this toxicity. However, no response was seen, and one might question the consequences of this strategy on efficacy [11].

Similar limitations have also been seen with BiTEs such as Solitomab (MT110, AMG 110), a bispecific antibody targeting EpCAM (an antigen frequently overexpressed in solid tumors, but also expressed at lower levels in normal tissue, notably gastrointestinal tract). The phase 1 could not determine an adequate dose, due to the occurrence of dose-limiting toxicities (DLTs), mostly transaminitis and diarrhea [12].

Some clinical trials testing CAR-T cells directed against CEA (CEACAM5) experienced lung toxicity [13]. Despite previous report suggesting no expression in normal lungs, the authors suggested that the CAR-T cells induced upregulation of CEA in the lung epithelium following infusion, due to cytokine production. They also found some expression of CEA in lung resection from non-cancer tissue, suggesting that the antigen is indeed present despite prior reports. Conversely, another product targeting CEA (autologous T cells engineered to express a murine TCR targeting CEA) was associated with severe colitis due to expression of CEA in the large intestine [14].

The first patient treated with a CAR-T cell targeting HER2 died of lung toxicity [8]. It was thought to be related to a low expression of HER2 by the lung, along with a severe cytokine release syndrome.

Lastly, CAR-T cells target only membranes protein. Intracellular antigens can only be targeted through natural or artificial TCR [15].

Thus, the selection of surface antigens for solid tumors may be hindered by limited expression of the antigen in normal tissue but sufficient to induce toxicity.

Tumor antigen heterogeneity

One of the most frequent escape mechanisms to CAR-T therapy in hematologic tumors is the loss of the target antigen [16]. Similarly, in patients treated with EGFRvIII-targeting CAR-T cells, 7 patients underwent surgery following treatment, due to clinical deterioration [17]. In 5 patients, decrease of EGFRvIII expression was confirmed; and one subject was found to have heterogeneous expression of EGFRvIII between different regions of the tumor. This analysis clearly demonstrated that solid tumors also frequently escape under the pressure of CAR-T cells, and that heterogeneous expression of the target might limit the efficacy of the product. A similar down-regulation of the target has also been reported in one patient who underwent surgery after treatment with IL13Ra2-targeting CAR-T cells for glioblastoma [18].

Similar mechanisms are likely to occur with BiTEs, and has been documented in hematologic malignancies with blinatumomab, a CD19/CD3 bispecific antibody [19].

Local immune suppression

In solid tumors, tumor infiltrating T cells may be rendered dysfunctional due to immunosuppressive mechanisms in the tumor microenvironment. These mechanisms include extrinsic suppression by regulatory cell populations, inhibition by ligands such as programmed death ligand-1 (PD-L1), metabolic dysregulation by enzymes such as indoleamine-2,3-dioxygenase, and the action of soluble inhibitory factors such as transforming growth factor-beta (reviewed in [20]). In preclinical models, CAR-T cells were found to have impaired functionality after reaching the tumor microenvironment [21]. In patients with glioblastoma treated with CAR-T cells targeting EGFRvIII, in situ evaluation of the tumor environment demonstrated increased expression of inhibitory molecules and infiltration by regulatory T cells [17].

Challenges faced only by CAR-T cells or BiTEs

CAR-T cell manufacturing

Ex vivo engineering of CAR-T cells is currently complex from a logistical point of view. Viral vectors (either lenti- or retroviruses) are used for the manufacturing [22], in a process that is time-consuming and requires specialized biosafety level 2 facilities and trained staff resources. These manufacturing issues hinder their availability in clinical routine, at least for autologous CAR-T cells (Table 1). Production failures of CAR-T cells have been observed in a small percentage of patients with hematologic malignancies. The possibility to generate and expand CAR-T cells from patients with solid tumors who have been previously exposed to chemotherapy, and the rate of production failure are yet undetermined due to limited experience in these patients.

Exposure to the treatment

Exposure to the treatment represent different challenges for CAR-T cells and BiTEs.

CAR-T cells are injected after a lymphodepleting chemotherapy to facilitate their expansion and persistence in vivo. In hematologic malignancies, this expansion and persistence have been shown to correlate with efficacy. This might be related to the fact that anti-CD19 CAR-T cells directly encountered their target in the blood and could thus be immediately activated. In solid tumors, the expansion of CAR-T cells seems to be reduced. Expansion of anti-CEA CAR-T cells was shown to be limited [13]. Anti-HER2 CAR-T cells tested in the treatment of sarcomas persisted poorly with only low-levels detected at 6 weeks, and, at 3 months, only 4 out of 12 patients had still detectable CAR-T cells [23]. Short persistence was also an issue in 2 trials using CAR-T cells targeting TAG72 for the treatment of colorectal metastases [24]. CAR-T cells could only be detected during a short period (≤ 14 weeks). A similar observation was made with CAR-T cells targeting GD2 for the treatment of neuroblastoma [25]. There was no persistence even at higher doses and no CAR-T cells could be detected beyond Day45.

Low exposure to BiTEs was mainly due to the short half-life of many constructs (scFv), including first-generation BiTEs (half-life = 2 to 3 h for blinatumomab). This short half-life required continuous infusion. Discontinuous administration of a BiTE targeting CEA has been associated with low exposure, which may explain the lack of clinical activity in the phase I trial [26]. The administration was also associated with the development of anti-drug antibodies, which is also another cause of low exposure to drugs [27].

Moreover, T cell dysfunction is a hallmark of many cancer [28] and may negatively impact the results of both T cell-directed therapies. Albeit lack of clinical evidence, this should be an area of vigilance.

Trafficking to the tumors

In a phase I study of folate-receptor targeting cells, no specific trafficking to the tumors was seen, likely explaining the lack of clinical activity [29]. Another important finding of the CAR-T cells targeting TAG72 trials was that even if the cells were able to traffic to the tumors, they seemed to be excluded from the center of the tumor mass [24]. Trafficking through the blood–brain barrier might also be challenging although responses have been seen in hematologic malignancies with central nervous system (CNS) involvement [30].

While BiTEs do not actively traffic to the tumor, their activity is based on trafficking of endogenous T cells that can encounter similar difficulties. Their ability to penetrate in a tumor (for example through the blood–brain barrier, or in a hypovascular solid tumor) should also be confirmed.

Opportunities to overcome the challenges

The different opportunities to overcome the challenges for T cell-directed therapies efficacy in solid tumors are presented in Fig. 1b.

Improving antigen targeting

Selection of antigens with limited expression on normal tissue

Glypican-3 is a protein expressed in hepatocellular carcinoma with very limited expression on normal cells, and different trials have shown the feasibility and lack of toxicity of CAR-T cells targeting Glypican-3 [31]. A BiTE targeting Glypican-3 has also been developed [32]. Similarly, PSMA seems a promising target for T cell-directed therapies. In addition to a CAR-T cell trial [33], positive results of the BiTE pasotuxizumab were presented, showing decrease of PSA by more than 50% in 3 patients out of 15 treated, with many other patients experiencing lower decrease [34].

Discovery of novel antigens

Proteomics approaches have been used to discover new tumor-associated antigens with better specificity [35]. The use of antigens for which circulating T cells will have limited access in normal cells may be the source of less toxic therapies. CAR-T cell targeting GUCY2C, a glycoprotein expressed in normal tissue only on the luminal membranes but homogeneously on cancer cells, have been engineered to treat colorectal cancers [36]. Claudin 18.2 is a component of the tight junction, present only in gastric normal mucosa, and expressed in various solid tumors. Targeting of Claudin 18.2 by CAR-T cells has shown promising results [37], and a BiTE compound, AMG 910, has been developed and has now entered clinical evaluation [38, 39].

Finally, an interesting approach was to use chlorotoxin, a peptide known to bind specifically to glioblastoma cells, even if the binding site is not well defined. CAR-T cells targeting chlorotoxin have been developed in a preclinical model to treat glioblastoma [40].

Transient expression and safety switch

To mitigate toxicity, T cells with transient expression of the CAR have been designed. This would limit the off-target toxicity, but with the caveat of requiring repeat infusion of the cells. This approach was proved feasible in a trial of CAR-T cells targeting mesothelin for the treatment of pancreatic adenocarcinoma, with no toxicity reported, and stabilization in 2 out of 6 patients treated [41]. Another mechanism is the use of transcriptional activation in response to recognition of user-specified antigens, using synthetic Notch (synNotch) receptors [42, 43]. This allows the activation of the CAR-T cells only in the context of the tumor. Other approaches include the inclusion in the construct of a safety switch which enables removal of CAR-T cells by inducing their apoptosis in case they become too toxic [44,45,46].

Targeting intracellular antigens through TCR-directed therapies

Another important avenue is the use of TCR-directed therapies. One major advantage is to expand potential targeting to intracellular molecules, some of which can be found mutated in solid tumors. One caveat of the approach being that this kind of therapies will depend on MHC presentation and will thus be HLA-compatible. MHC expression downregulation by the tumor cells is a frequent immune escape mechanism and has also to be considered. Approaches similar to CAR-T cells have been used, in which a modified TCR is expressed, targeting the antigen of interest [47]. These types of construct has already been successful in targeting NY-ESO-1 for the treatment of multiple myeloma and synovial sarcoma [6, 48]. Frequent responses were seen, including in synovial sarcoma, with a similar product targeting MAGE-A4 [49]. Two different products targeting alpha-feto-protein, an antigen frequently expressed in hepatocellular carcinoma, have also been associated with responses [50, 51].

Similar strategies are pursed with BiTEs. The immune-mobilizing monoclonal TCRs against cancer (ImmTACs) target TCR-presenting antigens, and recruits effector cells [52]. A proof of concept of this approach was given with tebentafusp, a TCR/Anti-CD3 bispecific fusion protein targeting gp100, which was able to induce responses in melanoma patients, including difficult to treat uveal melanoma [53].

Using tumor-infiltrating lymphocytes

Another avenue for ACT in solid tumors consists in the use of endogenous T cells. TILs can be harvested from the tumor, then expanded in vitro, and finally infused back into the patients. This way, efficacy might be found despite ignoring the actual target of the infused T cells. Positive results were shown in several types of tumors [54,55,56,57,58,59].

Thus, many new options are used to develop alternative ways to target tumor cells.

Combinational approaches to tackle tumor heterogeneity

Tumor heterogeneity could be bypassed by eliciting immunogenicity towards a broader range of antigens. This is the concept of epitope spreading, where the CAR-T cells express co-stimulatory molecules such as CD40L or 4-1BBL to stimulate endogenous immune responses [60, 61].

Antigen loss and tumor heterogeneity were shown to be an important escape mechanism to T cell-directed therapies. Targeting different tumor antigens is a theoretical approach to tackle tumor heterogeneity. Bicistronics CAR-T cells targeting both CD19 and CD22 are being developed in the clinic [62, 63]. The same group described the first tandem CAR-T cells targeting HER2 and IL13Ra2, then trivalent CAR-T cells targeting HER2, IL13Rα2 and ephrin-A2, and showed better results in preclinical models of glioblastoma compared to monovalent CAR-T cells [64, 65]. Another similar approach is to treat a patient with different CAR-T cells targeting different antigens [66].

An elegant approach has been used to overcome EGFRvIII antigen loss, with EGFRvIII-targeting CAR-T cells which secrete a BiTE targeting wild-type EGFR [67]. With this product, CAR-T cells are directed to the tumor due to the specificity of the EGFRvIII mutation, secrete a BiTE that can target tumor cells expressing normal EGFR through tumor heterogeneity or antigen loss. The expression by the CAR-T cells avoid systemic exposure to the EGFR BiTE which would have resulted in “on-target, off-tumor” toxicity. This is also a fine example of how CAR-T cells and BiTEs can be combined.

Improving exposure, persistence and activity of the products

Extending BiTEs half-life

New half-life extended BiTEs have been developed to improve the exposure of BiTEs, and to avoid continuous infusion [68]. Initial BiTEs lack the Fc portion, and thus were not enable to recycle through neonatal crystallizable fragment receptor-mediated (FcRn). Fusion with the Fc domain enables engineering of new BiTEs with extended half-life and discontinued administration.

Improving BiTEs activity

A further development is the use of trispecific antibodies (TriTE), targeting one antigen but using different T-cell engagement molecules. One example is the anti-myeloma compound SAR442257 which targets CD38, and recruits T cells via CD3 and CD28 [69, 70]. Efforts are currently conducted to develop such molecules for the treatment of solid tumors, but none have reached clinical stage yet [71].

Improving persistence and tackling exhaustion of CAR-T cells

Persistence and activity of CAR-T cells were improved in second- and third-generation CAR-T cells, where the products also contain additional costimulatory domains (4-1BB, CD28, OX40 and/or ICOS) [2, 72]. It is also important to use an adequate lymphodepleting regimen, which has been shown to improve results of HER2-targeting CAR-T cells for the treatment of sarcoma [73, 74]. Moreover, it was shown that different types of T cells might have different killing potency, the naïve and central memory T cells having higher activity than effector memory T cells, suggesting that the selection of a correct proportion of the different cells might improve the overall results [75]. This process might be automated [76]. A deep analysis of a responding patient showed that a single clone, in which the CAR was inserted randomly within the TET2 gene, was responsible for the response [77]. The disruption of TET2 induced a central memory phenotype, which was probably responsible for its increased activity. While modification of TET2 might be too risky, modifications of other parameters related to exhaustion, such as NR4a or Jun might augment CAR-T activity [78, 79].

Improving trafficking

The delivery of the drug to the tumor site might be improved by different ways. A platform to enable bispecific biologics to cross the blood–brain barrier has been developed [80].

For CAR-T cells, multiple trials investigated local injection. This could be done in an anatomical cavity (pleura, peritoneum), via a device placed surgically (for CNS tumors) or via intra-arterial delivery (such as hepatic artery catheterization), or by direct intra-tumoral injection. The described response of a glioblastoma to IL13Rα2-targeted CAR-T was achieved after intracranial delivery [81]. Intra-tumoral injection of cMET targeting CAR-T cells was shown to be feasible in metastatic breast cancer [82]. Feasibility of intra-pleural injection of CAR-T cells targeting mesothelin was also demonstrated [83]. Intra-arterial hepatic infusion of CEA-targeting CAR-T cell was done in different clinical trials, with one patient showing response [84, 85].

Another strategy to improve trafficking is to make the CAR-T cells express chemokine receptors that can redirect the CAR-T cells into the tumors. CCR2-expressing CAR-T cells targeting GD2 were shown to have better activity in vivo [86]. There is however controversy about the best chemokine receptor to use for improved trafficking [87].

Reversing the immunosuppressive microenvironment

Combination with immune checkpoint inhibitors

With the advent of ICI, their use in combination with CAR-T cells and BiTEs become an evident avenue of research. First evidence of potential additive effects was shown in a phase 1 trial of a BiTE targeting CEA in patients with metastatic colorectal cancer [88]. The trial had 2 cohorts, with or without the addition of the anti-PD-L1 antibody atezolizumab. The response rates without and with atezolizumab were 6% vs 18% (only 1 patient was MSI, all other responders were MSS) respectively, while the disease control rates were 45% vs 82%, respectively. Combination trials of CAR-T cells and ICI have also been presented, with a suggestion that ICI improved responses in patients treated with intra-pleural infusion of mesothelin-targeting CAR-T cells [83]. Conversely, a small phase 1 trial of combinations based on GD2 CAR-T cells showed that the lymphodepletion regimen had huge impact, but the addition of the anti-PD-1 antibody pembrolizumab did not clearly improve the results (but the number of patients was very limited and the follow-up was short) [89]. Several clinical trials are ongoing using such combination. A derived approach is to develop BiTE targeting PD-L1 expressing cells (so called checkpoint-inhibitory T cell engagers (CiTEs)) that will target the cells promoting immunosuppression [90].

Expression of cytokines

Another approach to tackle the immunosuppressive microenvironment is to make the CAR-T cells secrete stimulatory cytokines. In a preclinical model of pancreatic cancer, IL-18 expressing CAR-T cells targeting CEA improved results over conventional CAR-T cells [91].

Finally, some authors proposed the combination of local treatment with CAR-T cell administration. For example, radiation was suggested to have the potential to improve Immuno-Oncology results, and combination of intra-arterial hepatic infusion of CEA-targeting CAR-T cells with selective internal radiation therapy was demonstrated feasible and associated with responses in liver metastases [92].

Improving CAR-T cell manufacturing

Autologous CAR-T cells are patient-derived personalized products, thus associated with the absence of allogeneic rejection, which enables long-term persistence. Nonetheless, this bespoke manufacturing process presents many disadvantages, such as a delay in the availability of the treatment (2 to 4 weeks), a complex manufacturing procedure and an increase cost. Current CAR-T cell engineering mainly uses viral vectors, that should be handled in specialized facilities. Alternative insertion strategies are under development, such as sleeping beauty or piggy-bac transposons, that could facilitate the manufacturing processes [22]. Another strategy to potentially address these issues is the development of universal CAR-T cells [93]. The principle is to use allogeneic T cells from healthy donors in order to produce “off-the-shelf” allogeneic CAR-T cells. This approach has the potential to simplify and scale-up the manufacturing processes, allowing for an immediate delivery of the treatment at reduced costs [94]. In order to produce allogeneic CAR-T cells with no potential for graft-versus-host disease (GVHD), the endogenous TCR should be disrupted through gene editing (zinc finger nuclease, transcription activator-like effector nuclease (TALEN) or CRISPR/Cas9 methods) [22, 95]. However, allogeneic CAR-T cells may be rapidly eliminated by the host immune system, thus limiting their persistence and clinical efficacy. Application of TALEN-based universal CAR-T cells targeting CD19 (UCART19) was recently reported for 21 patients with relapsed/refractory B cell acute lymphoblastic leukemia [96]. Despite high rates of complete remission among patients who received the most immunosuppressive conditioning regimen, a short duration of response and limited CAR-T persistence were observed, and a majority of patients had to undergo allogeneic stem cell transplantation. These results emphasize the need to decrease allogeneic rejection of universal CAR-cells. Regarding solid tumors, a preclinical model of universal EGFRvIII CAR-T cells has been developed [97]. Phase 1 clinical trials with universal CAR-T cells targeting mesothelin (NCT03545815) and NKG2D (NCT03692429) are ongoing.

Conclusion and perspectives

CAR-T cells and BiTEs both represent promising approaches of immunotherapy and are still at the beginning of their clinical development in solid tumors. The last generations of such T cell-directed therapies have the potential to overcome the challenges they are facing and have shown promising preclinical results. None can now predict how CAR-T cells and/or BiTEs will be used in the future treatment strategies and large clinical studies are eagerly awaited. At this point, it is difficult to speculate which cancers will benefit most from these therapies since clinical results in solid tumors are limited. One may expect that tumors which are more likely to benefit from CAR-T cells and BiTEs are: i) tumors which do not respond to checkpoint inhibitors because they lack pre-existing antitumor T cells (“cold tumors”), ii) tumors with a targetable surface antigen (either a surface neoantigen or an overexpressed antigen which can be targeted with limited organ toxicity) which is expressed homogeneously by all tumor cells (to avoid immune escape), and iii) tumors with a permissive and poorly immunosuppressive microenvironment.

To date, the development of CAR-T cells and BiTEs has focused on chemo-refractory/relapsed patients. However, these immunotherapies may be more efficient if given earlier in the therapeutic strategy, as suggested in lymphoma patients [98]. In the future, these immunotherapies could also be combined with standard chemotherapy and/or targeted therapies: these treatments could reduce the tumor burden and/or modulate the immune response [99, 100].

Finally, the question may be not to compare CARs versus BiTEs, or how these innovative immunotherapies will compare to standard chemotherapy, but whether how to combine all therapeutic modalities.

Availability of data and materials

Not applicable.





Adoptive cell therapy




Bispecific T cell engager




Chimeric antigen receptor


Checkpoint-inhibitory T cell engagers


Central nervous system


Dose-limiting toxicities


Neonatal fragment crystallizable receptor


Graft-versus-host disease


Immune checkpoint inhibitors


Major histocompatibility complex


Programmed death ligand-1


Single-chain variable fragment


Transcription activator-like effector nuclease


T cell receptor


Tumor-infiltrating lymphocytes


Trispecific antibodies


  1. Goebeler M-E, Bargou RC. T cell-engaging therapies—BiTEs and beyond. Nat Rev Clin Oncol. 2020;17(7):418–34.

    Article  PubMed  Google Scholar 

  2. June CH, Sadelain M. Chimeric antigen receptor therapy. N Engl J Med. 2018;379(1):64–73.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  3. Strohl N. Bispecific T-cell redirection versus chimeric antigen receptor (CAR)-T cells as approaches to kill cancer cells. Antibodies. 2019;8(3):41.

    Article  CAS  PubMed Central  Google Scholar 

  4. Sadelain M, Rivière I, Brentjens R. Targeting tumours with genetically enhanced T lymphocytes. Nat Rev Cancer. 2003;3(1):35–45.

    Article  CAS  PubMed  Google Scholar 

  5. Hinrichs CS, Rosenberg SA. Exploiting the curative potential of adoptive T-cell therapy for cancer. Immunol Rev. 2014;257(1):56–71.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  6. D’Angelo SP, Melchiori L, Merchant MS, Bernstein D, Glod J, Kaplan R, et al. Antitumor activity associated with prolonged persistence of adoptively transferred NY-ESO-1 (c259)T cells in synovial sarcoma. Cancer Discov. 2018;8(8):944–57.

    Article  PubMed  CAS  PubMed Central  Google Scholar 

  7. Slaney CY, Wang P, Darcy PK, Kershaw MH. CARs versus BiTEs: a comparison between T cell-redirection strategies for cancer treatment. Cancer Discov. 2018;8(8):924–34.

    Article  CAS  PubMed  Google Scholar 

  8. Morgan RA, Yang JC, Kitano M, Dudley ME, Laurencot CM, Rosenberg SA. Case report of a serious adverse event following the administration of T cells transduced with a chimeric antigen receptor recognizing ERBB2. Mol Ther. 2010;18(4):843–51.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  9. Yu W-L, Hua Z-C. Chimeric antigen receptor T-cell (CAR T) therapy for hematologic and solid malignancies: efficacy and safety—a systematic review with meta-analysis. Cancers. 2019;11(1):47.

    Article  CAS  PubMed Central  Google Scholar 

  10. Lamers CH, Sleijfer S, van Steenbergen S, van Elzakker P, van Krimpen B, Groot C, et al. Treatment of metastatic renal cell carcinoma with CAIX CAR-engineered T cells: clinical evaluation and management of on-target toxicity. Mol Ther. 2013;21(4):904–12.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  11. Lamers CHJ, Klaver Y, Gratama JW, Sleijfer S, Debets R. Treatment of metastatic renal cell carcinoma (mRCC) with CAIX CAR-engineered T-cells-a completed study overview. Biochem Soc Trans. 2016;44(3):951–9.

    Article  CAS  PubMed  Google Scholar 

  12. Kebenko M, Goebeler M-E, Wolf M, Hasenburg A, Seggewiss-Bernhardt R, Ritter B, et al. A multicenter phase 1 study of solitomab (MT110, AMG 110), a bispecific EpCAM/CD3 T-cell engager (BiTE®) antibody construct, in patients with refractory solid tumors. OncoImmunology. 2018;e1450710.

  13. Thistlethwaite FC, Gilham DE, Guest RD, Rothwell DG, Pillai M, Burt DJ, et al. The clinical efficacy of first-generation carcinoembryonic antigen (CEACAM5)-specific CAR T cells is limited by poor persistence and transient pre-conditioning-dependent respiratory toxicity. Cancer Immunol Immunother. 2017;66(11):1425–36.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  14. Parkhurst MR, Yang JC, Langan RC, Dudley ME, Nathan D-AN, Feldman SA, et al. T cells targeting carcinoembryonic antigen can mediate regression of metastatic colorectal cancer but induce severe transient colitis. Mol Ther. 2011;19(3):620–6.

    Article  CAS  PubMed  Google Scholar 

  15. Rath JA, Arber C. Engineering strategies to enhance TCR-based adoptive T cell therapy. Cells. 2020;9(6).

  16. Neelapu SS, Rossi JM, Jacobson CA, Locke FL, Miklos DB, Reagan PM, et al. CD19-loss with preservation of other B cell lineage features in patients with large B cell lymphoma who relapsed post-axi-cel. Washington: American Society of Hematology; 2019.

    Book  Google Scholar 

  17. O’Rourke DM, Nasrallah MP, Desai A, Melenhorst JJ, Mansfield K, Morrissette JJD, et al. A single dose of peripherally infused EGFRvIII-directed CAR T cells mediates antigen loss and induces adaptive resistance in patients with recurrent glioblastoma. Sci Transl Med. 2017;9(399).

  18. Brown CE, Badie B, Barish ME, Weng L, Ostberg JR, Chang W-C, et al. Bioactivity and safety of IL13Rα2-redirected chimeric antigen receptor CD8+ T cells in patients with recurrent glioblastoma. Clin Cancer Res. 2015;21(18):4062–72.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  19. Braig F, Brandt A, Goebeler M, Tony H-P, Kurze A-K, Nollau P, et al. Resistance to anti-CD19/CD3 BiTE in acute lymphoblastic leukemia may be mediated by disrupted CD19 membrane trafficking. Blood. 2017;129(1):100–4.

    Article  CAS  PubMed  Google Scholar 

  20. Gajewski TF, Meng Y, Blank C, Brown I, Kacha A, Kline J, et al. Immune resistance orchestrated by the tumor microenvironment. Immunol Rev. 2006;213:131–45.

    Article  CAS  PubMed  Google Scholar 

  21. Moon EK, Wang L-C, Dolfi DV, Wilson CB, Ranganathan R, Sun J, et al. Multifactorial T-cell hypofunction that is reversible can limit the efficacy of chimeric antigen receptor-transduced Human T cells in solid tumors. Clin Cancer Res. 2014;20(16):4262.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  22. Rivière I, Sadelain M. Chimeric antigen receptors: a cell and gene therapy perspective. Mol Ther. 2017;25(5):1117–24.

    Article  PubMed  PubMed Central  CAS  Google Scholar 

  23. Ahmed N, Brawley VS, Hegde M, Robertson C, Ghazi A, Gerken C, et al. Human epidermal growth factor receptor 2 (HER2) -specific chimeric antigen receptor-modified T cells for the immunotherapy of HER2-positive sarcoma. J Clin Oncol. 2015;33(15):1688–96.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  24. Hege KM, Bergsland EK, Fisher GA, Nemunaitis JJ, Warren RS, McArthur JG, et al. Safety, tumor trafficking and immunogenicity of chimeric antigen receptor (CAR)-T cells specific for TAG-72 in colorectal cancer. J Immunol Ther Cancer. 2017.

    Article  Google Scholar 

  25. Straathof K, Flutter B, Wallace R, Thomas S, Cheung G, Collura A, et al. Abstract CT145: a cancer research UK phase I trial of anti-GD2 chimeric antigen receptor (CAR) transduced T-cells (1RG-CART) in patients with relapsed or refractory neuroblastoma. Cancer Res. 2018;78(13 Supplement):CT145.

  26. Pishvaian M, Morse MA, McDevitt J, Norton JD, Ren S, Robbie GJ, et al. Phase 1 dose escalation study of MEDI-565, a bispecific T-cell engager that targets human carcinoembryonic antigen, in patients with advanced gastrointestinal adenocarcinomas. Clin Colorectal Cancer. 2016;15(4):345–51.

    Article  PubMed  Google Scholar 

  27. Moek KL, Fiedler WM, von Einem JC, Verheul HM, Seufferlein T, de Groot DJ, et al. 427P Phase I study of AMG 211/MEDI-565 administered as continuous intravenous infusion (cIV) for relapsed/refractory gastrointestinal (GI) adenocarcinoma. Ann Oncol. 2018;29(suppl_8):mdy279. 414.

  28. Thommen DS, Schumacher TN. T cell dysfunction in cancer. Cancer Cell. 2018;33(4):547–62.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  29. Kershaw MH, Westwood JA, Parker LL, Wang G, Eshhar Z, Mavroukakis SA, et al. A phase I study on adoptive immunotherapy using gene-modified T cells for ovarian cancer. Clin Cancer Res. 2006;12(20):6106.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  30. Frigault MJ, Dietrich J, Martinez-Lage M, Leick M, Choi BD, DeFilipp Z, et al. Tisagenlecleucel CAR T-cell therapy in secondary CNS lymphoma. Blood. 2019;134(11):860–6.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  31. Shi D, Shi Y, Kaseb AO, Qi X, Zhang Y, Chi J, et al. Chimeric antigen receptor-glypican-3 T-cell therapy for advanced hepatocellular carcinoma: results of phase I trials. Clin Cancer Res. 2020;26(15):3979–89.

    Article  CAS  PubMed  Google Scholar 

  32. Bi Y, Jiang H, Wang P, Song B, Wang H, Kong X, et al. Treatment of hepatocellular carcinoma with a GPC3-targeted bispecific T cell engager. Oncotarget. 2017;8(32):52866–76.

    Article  PubMed  PubMed Central  Google Scholar 

  33. Junghans RP, Ma Q, Rathore R, Gomes EM, Bais AJ, Lo ASY, et al. Phase I trial of anti-PSMA designer CAR-T cells in prostate cancer: possible role for interacting interleukin 2-T cell pharmacodynamics as a determinant of clinical response. Prostate. 2016;76(14):1257–70.

    Article  CAS  PubMed  Google Scholar 

  34. Hummel H-D, Kufer P, Grüllich C, Deschler-Baier B, Chatterjee M, Goebeler M-E, et al. Phase 1 study of pasotuxizumab (BAY 2010112), a PSMA-targeting Bispecific T cell Engager (BiTE) immunotherapy for metastatic castration-resistant prostate cancer (mCRPC). American Society of Clinical Oncology; 2019.

  35. Zhu Q, Liu M, Dai L, Ying X, Ye H, Zhou Y, et al. Using immunoproteomics to identify tumor-associated antigens (TAAs) as biomarkers in cancer immunodiagnosis. Autoimmun Rev. 2013;12(12):1123–8.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  36. Magee MS, Abraham TS, Baybutt TR, Flickinger JCJ, Ridge NA, Marszalowicz GP, et al. Human GUCY2C-targeted chimeric antigen receptor (CAR)-expressing T cells eliminate colorectal cancer metastases. Cancer Immunol Res. 2018;6(5):509–16.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  37. Zhan X. Phase I trial of Claudin 18.2-specific chimeric antigen receptor T cells for advanced gastric and pancreatic adenocarcinoma. In: Xianbao Zhan BW, éditeur. ASCO Annual Meeting: American Society of Clinical Oncology; 2019:

  38. Bailis JM, Lutterbuese P, Thomas O, Locher K, Harrold J, Boyle M, et al. Abstract 3364: Preclinical evaluation of BiTE®immune therapy targeting MUC17 or CLDN18.2 for gastric cancer. Cancer Res. 2020;80(16 Supplement):3364.

  39. Lordick F, Chao J, Buxò E, van Laarhoven HWM, Lima CMR, Lorenzen S, et al. 1496TiP Phase I study evaluating safety and tolerability of AMG 910, a half-life extended bispecific T cell engager targeting claudin-18.2 (CLDN18.2) in gastric and gastroesophageal junction (G/GEJ) adenocarcinoma. Ann Oncol. 2020;31:S928‑9.

  40. Wang D, Starr R, Chang W-C, Aguilar B, Alizadeh D, Wright SL, et al. Chlorotoxin-directed CAR T cells for specific and effective targeting of glioblastoma. Sci Transl Med. 2020;12(533).

  41. Beatty GL, O’Hara MH, Lacey SF, Torigian DA, Nazimuddin F, Chen F, et al. Activity of mesothelin-specific chimeric antigen receptor T cells against pancreatic carcinoma metastases in a phase 1 trial. Gastroenterology. 2018;155(1):29–32.

    Article  CAS  PubMed  Google Scholar 

  42. Roybal KT, Williams JZ, Morsut L, Rupp LJ, Kolinko I, Choe JH, et al. Engineering t cells with customized therapeutic response programs using synthetic notch receptors. Cell. 2016;167(2):419-432.e16.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  43. Morsut L, Roybal KT, Xiong X, Gordley RM, Coyle SM, Thomson M, et al. Engineering Customized Cell Sensing and Response Behaviors Using Synthetic Notch Receptors. Cell. 2016;164(4):780–91.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  44. Gargett T, Brown MP. The inducible caspase-9 suicide gene system as a « safety switch » to limit on-target, off-tumor toxicities of chimeric antigen receptor T cells. Front Pharmacol. 2014;5:235.

    Article  PubMed  PubMed Central  CAS  Google Scholar 

  45. Rodgers DT, Mazagova M, Hampton EN, Cao Y, Ramadoss NS, Hardy IR, et al. Switch-mediated activation and retargeting of CAR-T cells for B-cell malignancies. Proc Natl Acad Sci USA. 2016;113(4):E459-468.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  46. Minagawa K, Al-Obaidi M, Di Stasi A. Generation of suicide gene-modified chimeric antigen receptor-redirected T-cells for cancer immunotherapy. Methods Mol Biol. 2019;1895:57–73.

    Article  CAS  PubMed  Google Scholar 

  47. Spear TT, Nagato K, Nishimura MI. Strategies to genetically engineer T cells for cancer immunotherapy. Cancer Immunol Immunother. 2016;65(6):631–49.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  48. Stadtmauer EA, Faitg TH, Lowther DE, Badros AZ, Chagin K, Dengel K, et al. Long-term safety and activity of NY-ESO-1 SPEAR T cells after autologous stem cell transplant for myeloma. Blood Adv. 2019;3(13):2022–34.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  49. Hong DS. Phase I dose escalation and expansion trial to assess the safety and efficacy of ADP-A2M4 SPEAR T cells in advanced solid tumors. In: David S. Hong BAVT, éditeur. ASCO Virtual Scientific Program: American Society of Clinical Oncology; 2020:

  50. Meyer T, Sangro B, Mahipal A, Goyal L, Frigault MJ, Sarker D, et al. Updated data from an ongoing study with ADP-A2AFP spear T-cells. J Hepatol. 2020;73:S910–1.

    Article  Google Scholar 

  51. Liu C. ET140202 t-cells: A novel therapy targeting AFP/MHC complex, that is both safe and effective in treating metastatic hepatocellular carcinoma. In: Chang Liu HL, éditeur. ASCO Annual Meeting: American Society of Clinical Oncology; 2019:

  52. Oates J, Hassan NJ, Jakobsen BK. ImmTACs for targeted cancer therapy: Why, what, how, and which. Mol Immunol. 2015;67(2 Pt A):67–74.

    Article  CAS  PubMed  Google Scholar 

  53. Middleton MR, McAlpine C, Woodcock VK, Corrie P, Infante JR, Steven NM, et al. Tebentafusp, a TCR/anti-cd3 bispecific fusion protein targeting gp100, potently activated antitumor immune responses in patients with metastatic melanoma. Clin Cancer Res. 2020.

    Article  PubMed  PubMed Central  Google Scholar 

  54. Nguyen LT, Saibil SD, Sotov V, Le MX, Khoja L, Ghazarian D, et al. Phase II clinical trial of adoptive cell therapy for patients with metastatic melanoma with autologous tumor-infiltrating lymphocytes and low-dose interleukin-2. Cancer Immunol Immunother. 2019;68(5):773–85.

    Article  CAS  PubMed  Google Scholar 

  55. Stevanović S, Helman SR, Wunderlich JR, Langhan MM, Doran SL, Kwong MLM, et al. A phase II study of tumor-infiltrating lymphocyte therapy for human papillomavirus-associated epithelial cancers. Clin Cancer Res. 2019;25(5):1486–93.

    Article  PubMed  Google Scholar 

  56. Jiang S-S, Tang Y, Zhang Y-J, Weng D-S, Zhou Z-G, Pan K, et al. A phase I clinical trial utilizing autologous tumor-infiltrating lymphocytes in patients with primary hepatocellular carcinoma. Oncotarget. 2015;6(38):41339–49.

    Article  PubMed  PubMed Central  Google Scholar 

  57. Pedersen M, Westergaard MCW, Milne K, Nielsen M, Borch TH, Poulsen LG, et al. Adoptive cell therapy with tumor-infiltrating lymphocytes in patients with metastatic ovarian cancer: a pilot study. Oncoimmunology. 2018;7(12):e1502905.

    Article  PubMed  PubMed Central  Google Scholar 

  58. Chandran SS, Somerville RPT, Yang JC, Sherry RM, Klebanoff CA, Goff SL, et al. Treatment of metastatic uveal melanoma with adoptive transfer of tumour-infiltrating lymphocytes: a single-centre, two-stage, single-arm, phase 2 study. Lancet Oncol. 2017;18(6):792–802.

    Article  PubMed  PubMed Central  Google Scholar 

  59. Goff SL, Dudley ME, Citrin DE, Somerville RP, Wunderlich JR, Danforth DN, et al. Randomized, prospective evaluation comparing intensity of lymphodepletion before adoptive transfer of tumor-infiltrating lymphocytes for patients with metastatic melanoma. J Clin Oncol. 2016;34(20):2389–97.

    Article  PubMed  PubMed Central  Google Scholar 

  60. Kuhn NF, Purdon TJ, van Leeuwen DG, Lopez AV, Curran KJ, Daniyan AF, et al. CD40 ligand-modified chimeric antigen receptor T cells enhance antitumor function by eliciting an endogenous antitumor response. Cancer Cell. 2019;35(3):473-488.e6.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  61. Lai J, Mardiana S, House IG, Sek K, Henderson MA, Giuffrida L, et al. Adoptive cellular therapy with T cells expressing the dendritic cell growth factor Flt3L drives epitope spreading and antitumor immunity. Nat Immunol. 2020;21(8):914–26.

    Article  CAS  PubMed  Google Scholar 

  62. Qin H, Nguyen SM, Ramakrishna S, Tarun S, Yang L, Verdini NP, et al. Novel CD19/CD22 bicistronic chimeric antigen receptors outperform single or bivalent cars in eradicating CD19+ CD22+, CD19-, and CD22-pre-B leukemia. Blood. 2017;130(Supplement 1):810–810.

    Article  Google Scholar 

  63. Amrolia PJ, Wynn R, Hough RE, Vora A, Bonney D, Veys P, et al. Phase I study of AUTO3, a bicistronic chimeric antigen receptor (CAR) T-cell therapy targeting CD19 and CD22, in pediatric patients with relapsed/refractory B-cell acute lymphoblastic leukemia (r/r B-ALL): Amelia Study. Washington: American Society of Hematology; 2019.

    Book  Google Scholar 

  64. Hegde M, Mukherjee M, Grada Z, Pignata A, Landi D, Navai SA, et al. Tandem CAR T cells targeting HER2 and IL13Rα2 mitigate tumor antigen escape. J Clin Investig. 2016;126(8):3036–52.

    Article  PubMed  PubMed Central  Google Scholar 

  65. Bielamowicz K, Fousek K, Byrd TT, Samaha H, Mukherjee M, Aware N, et al. Trivalent CAR T cells overcome interpatient antigenic variability in glioblastoma. Neuro Oncol. 2018;20(4):506–18.

    Article  CAS  PubMed  Google Scholar 

  66. Feng K-C, Guo Y-L, Liu Y, Dai H-R, Wang Y, Lv H-Y, et al. Cocktail treatment with EGFR-specific and CD133-specific chimeric antigen receptor-modified T cells in a patient with advanced cholangiocarcinoma. J Hematol Oncol. 2017;10(1):4.

    Article  PubMed  PubMed Central  Google Scholar 

  67. Choi BD, Yu X, Castano AP, Bouffard AA, Schmidts A, Larson RC, et al. CAR-T cells secreting BiTEs circumvent antigen escape without detectable toxicity. Nat Biotechnol. 2019;37(9):1049–58.

    Article  CAS  PubMed  Google Scholar 

  68. Einsele H, Borghaei H, Orlowski RZ, Subklewe M, Roboz GJ, Zugmaier G, et al. The BiTE (bispecific T-cell engager) platform: Development and future potential of a targeted immuno-oncology therapy across tumor types. Cancer. 2020;126(14):3192–201.

    Article  CAS  PubMed  Google Scholar 

  69. El-Murr N, Henry C, Francesconi E, Attenot F, Virone-Oddos A, Vidard L, et al. Abstract 5641: CD28 expression on multiple myeloma cells enhances the cytotoxic activity of CD38/CD28xCD3 trispecific T cell engager. Cancer Res. 2020;80(16 Supplement):5641.

    Google Scholar 

  70. Wu L, Seung E, Xu L, Rao E, Lord DM, Wei RR, et al. Trispecific antibodies enhance the therapeutic efficacy of tumor-directed T cells through T cell receptor co-stimulation. Nat Cancer. 2020;1(1):86–98.

    Article  PubMed  Google Scholar 

  71. Austin RJ, Lemon BD, Aaron WH, Barath M, Culp PA, DuBridge RB, et al. TriTACs, a novel class of T-cell-engaging protein constructs designed for the treatment of solid tumors. Mol Cancer Ther. 2021;20(1):109.

    CAS  PubMed  Google Scholar 

  72. Sadelain M, Brentjens R, Rivière I. The basic principles of chimeric antigen receptor design. Cancer Discov. 2013;3(4):388–98.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  73. Navai SA, Derenzo C, Joseph S, Sanber K, Byrd T, Zhang H, et al. Abstract LB-147: Administration of HER2-CAR T cells after lymphodepletion safely improves T cell expansion and induces clinical responses in patients with advanced sarcomas. Cancer Res. 2019;79(13 Supplement):LB-147.

  74. Hegde M, Joseph SK, Pashankar F, DeRenzo C, Sanber K, Navai S, et al. Tumor response and endogenous immune reactivity after administration of HER2 CAR T cells in a child with metastatic rhabdomyosarcoma. Nat Commun. 2020;11(1):3549.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  75. Sommermeyer D, Hudecek M, Kosasih PL, Gogishvili T, Maloney DG, Turtle CJ, et al. Chimeric antigen receptor-modified T cells derived from defined CD8+ and CD4+ subsets confer superior antitumor reactivity in vivo. Leukemia. 2016;30(2):492–500.

    Article  CAS  PubMed  Google Scholar 

  76. Blaeschke F, Stenger D, Kaeuferle T, Willier S, Lotfi R, Kaiser AD, et al. Induction of a central memory and stem cell memory phenotype in functionally active CD4+ and CD8+ CAR T cells produced in an automated good manufacturing practice system for the treatment of CD19+ acute lymphoblastic leukemia. Cancer Immunol Immunother. 2018;67(7):1053–66.

    Article  CAS  PubMed  Google Scholar 

  77. Fraietta JA, Nobles CL, Sammons MA, Lundh S, Carty SA, Reich TJ, et al. Disruption of TET2 promotes the therapeutic efficacy of CD19-targeted T cells. Nature. 2018;558(7709):307–12.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  78. Chen J, López-Moyado IF, Seo H, Lio C-WJ, Hempleman LJ, Sekiya T, et al. NR4A transcription factors limit CAR T cell function in solid tumours. Nature. 2019;567(7749):530‑4.

  79. Lynn RC, Weber EW, Sotillo E, Gennert D, Xu P, Good Z, et al. c-Jun overexpression in CAR T cells induces exhaustion resistance. Nature. 2019;576(7786):293–300.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  80. Farrington GK, Caram-Salas N, Haqqani AS, Brunette E, Eldredge J, Pepinsky B, et al. A novel platform for engineering blood-brain barrier-crossing bispecific biologics. FASEB J. 2014;28(11):4764–78.

    Article  CAS  PubMed  Google Scholar 

  81. Brown CE, Alizadeh D, Starr R, Weng L, Wagner JR, Naranjo A, et al. Regression of glioblastoma after chimeric antigen receptor T-cell therapy. N Engl J Med. 2016;375(26):2561–9.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  82. Tchou J, Zhao Y, Levine BL, Zhang PJ, Davis MM, Melenhorst JJ, et al. Safety and efficacy of intratumoral injections of chimeric antigen receptor (CAR) T cells in metastatic breast cancer. Cancer Immunol Res. 2017;5(12):1152–61.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  83. Adusumilli PS. Regional delivery of mesothelin-targeted CAR T cells for pleural cancers: Safety and preliminary efficacy in combination with anti-PD-1 agent. In: Prasad S. Adusumilli MGZ, éditeur. ASCO Annual Meeting: American Society of Clinical Oncology; 2019:

  84. Katz SC, Burga RA, McCormack E, Wang LJ, Mooring W, Point GR, et al. Phase I hepatic immunotherapy for metastases study of intra-arterial chimeric antigen receptor-modified T-cell therapy for CEA+ liver metastases. Clin Cancer Res. 2015;21(14):3149–59.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  85. Katz SC, Moody AE, Guha P, Hardaway JC, Prince E, LaPorte J, et al. HITM-SURE: Hepatic immunotherapy for metastases phase Ib anti-CEA CAR-T study utilizing pressure enabled drug delivery. J Immunother Cancer. 2020;8(2).

  86. Craddock JA, Lu A, Bear A, Pule M, Brenner MK, Rooney CM, et al. Enhanced tumor trafficking of GD2 chimeric antigen receptor T cells by expression of the chemokine receptor CCR2b. J Immunother. 2010;33(8):780–8.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  87. Mikucki ME, Fisher DT, Matsuzaki J, Skitzki JJ, Gaulin NB, Muhitch JB, et al. Non-redundant requirement for CXCR3 signalling during tumoricidal T-cell trafficking across tumour vascular checkpoints. Nat Commun. 2015;6:7458.

    Article  CAS  PubMed  Google Scholar 

  88. Tabernero J, Melero I, Ros W, Argiles G, Marabelle A, Rodriguez-Ruiz ME, et al. Phase Ia and Ib studies of the novel carcinoembryonic antigen (CEA) T-cell bispecific (CEA CD3 TCB) antibody as a single agent and in combination with atezolizumab: Preliminary efficacy and safety in patients with metastatic colorectal cancer (mCRC). American Society of Clinical Oncology; 2017.

  89. Heczey A, Louis CU, Savoldo B, Dakhova O, Durett A, Grilley B, et al. CAR T cells administered in combination with lymphodepletion and PD-1 inhibition to patients with neuroblastoma. Mol Ther. 2017;25(9):2214–24.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  90. Horn LA, Ciavattone NG, Atkinson R, Woldergerima N, Wolf J, Clements VK, et al. CD3xPDL1 bi-specific T cell engager (BiTE) simultaneously activates T cells and NKT cells, kills PDL1(+) tumor cells, and extends the survival of tumor-bearing humanized mice. Oncotarget. 2017;8(35):57964–80.

    Article  PubMed  PubMed Central  Google Scholar 

  91. Chmielewski M, Abken H. CAR T cells releasing IL-18 convert to T-Bet(high) FoxO1(low) effectors that exhibit augmented activity against advanced solid tumors. Cell Rep. 2017;21(11):3205–19.

    Article  CAS  PubMed  Google Scholar 

  92. Katz SC, Hardaway J, Prince E, Guha P, Cunetta M, Moody A, et al. HITM-SIR: phase Ib trial of intraarterial chimeric antigen receptor T-cell therapy and selective internal radiation therapy for CEA(+) liver metastases. Cancer Gene Ther. 2020;27(5):341–55.

    Article  CAS  PubMed  Google Scholar 

  93. Zhao J, Lin Q, Song Y, Liu D. Universal CARs, universal T cells, and universal CAR T cells. J Hematol Oncol. 2018;11(1):132.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  94. Depil S, Duchateau P, Grupp SA, Mufti G, Poirot L. ‘Off-the-shelf’ allogeneic CAR T cells: development and challenges. Nat Rev Drug Discov. 2020;19(3):185–99.

    Article  CAS  PubMed  Google Scholar 

  95. Poirot L, Philip B, Schiffer-Mannioui C, Le Clerre D, Chion-Sotinel I, Derniame S, et al. Multiplex genome-edited T-cell manufacturing platform for « off-the-shelf » adoptive T-cell immunotherapies. Cancer Res. 2015;75(18):3853–64.

    Article  CAS  PubMed  Google Scholar 

  96. Qasim W, Zhan H, Samarasinghe S, Adams S, Amrolia P, Stafford S, et al. Molecular remission of infant B-ALL after infusion of universal TALEN gene-edited CAR T cells. Sci Transl Med. 2017;9(374).

  97. Choi BD, Yu X, Castano AP, Darr H, Henderson DB, Bouffard AA, et al. CRISPR-Cas9 disruption of PD-1 enhances activity of universal EGFRvIII CAR T cells in a preclinical model of human glioblastoma. J Immunother Cancer. 2019;7(1):304.

    Article  PubMed  PubMed Central  Google Scholar 

  98. Neelapu SS. Interim analysis of ZUMA-12: A phase 2 study of axicabtagene ciloleucel (Axi-Cel) as first-line therapy in patients (Pts) with high-risk large B cell lymphoma (LBCL). ASH 2020, abstract #405;

  99. Ruella M, Kenderian SS, Shestova O, Fraietta JA, Qayyum S, Zhang Q, et al. The addition of the btk inhibitor ibrutinib to anti-CD19 Chimeric Antigen Receptor T CELLS (CART19) improves responses against mantle cell lymphoma. Clin Cancer Res. 2016;22(11):2684–96.

    Article  CAS  PubMed  Google Scholar 

  100. Gauthier J, Hirayama AV, Purushe J, Hay KA, Lymp J, Li D, et al. Feasibility and efficacy of CD19-targeted CAR-T cells with concurrent ibrutinib for CLL after ibrutinib failure. Blood. 2020;

  101. Feng K, Liu Y, Guo Y, Qiu J, Wu Z, Dai H, et al. Phase I study of chimeric antigen receptor modified T cells in treating HER2-positive advanced biliary tract cancers and pancreatic cancers. Protein Cell. 2018;9(10):838–47.

    Article  CAS  PubMed  Google Scholar 

  102. Haense N, Atmaca A, Pauligk C, Steinmetz K, Marmé F, Haag GM, et al. A phase I trial of the trifunctional anti Her2 × anti CD3 antibody ertumaxomab in patients with advanced solid tumors. BMC Cancer. 2016.

    Article  PubMed  PubMed Central  Google Scholar 

  103. Goff SL, Morgan RA, Yang JC, Sherry RM, Robbins PF, Restifo NP, et al. Pilot trial of adoptive transfer of chimeric antigen receptor-transduced T cells targeting EGFRvIII in patients with glioblastoma. J Immunother. 2019;42(4):126–35.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  104. Rosenthal MA, Balana C, van Linde ME, Sayehli C, Fiedler WM, Wermke M, et al. ATIM-49 (LTBK-01). AMG 596, A novel anti-EGFRVIII bispecific T Cell Engager (BITE®) Molecule For The Treatment Of Glioblastoma (GBM): planned interim analysis in recurrent GBM (RGBM). Neuro-Oncology. 2019;21(Supplement_6):vi283.

  105. Luke JJ, Fong L, Chung K, Tolcher AW, Kelly K, Hollebecque A, et al. 1220P—Phase I study evaluating safety, pharmacokinetics (PK), pharmacodynamics, and preliminary efficacy of ABBV-428, first-in-class mesothelin (MSLN)-CD40 bispecific, in patients (pts) with advanced solid tumours. Ann Oncol. 2019;30:v498–9.

    Article  Google Scholar 

  106. Straathof K, Flutter B, Wallace R, Jain N, Loka T, Depani S, et al. Antitumor activity without on-target off-tumor toxicity of GD2–chimeric antigen receptor T cells in patients with neuroblastoma. Sci Transl Med. 2020;12(571):eabd6169.

  107. Ogita Y, Weiss D, Sugaya N, Nakamura M, Ito H, Ishiguro T, et al. A phase 1 dose escalation (DE) and cohort expansion (CE) study of ERY974, an anti-Glypican 3 (GPC3)/CD3 bispecific antibody, in patients with advanced solid tumors. JCO. 2018;36(15_suppl):TPS2599.

  108. Zhang C, Wang Z, Yang Z, Wang M, Li S, Li Y, et al. Phase I escalating-dose trial of CAR-T therapy targeting CEA(+) metastatic colorectal cancers. Mol Ther. 2017;25(5):1248–58.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  109. Heiss MM, Murawa P, Koralewski P, Kutarska E, Kolesnik OO, Ivanchenko VV, et al. The trifunctional antibody catumaxomab for the treatment of malignant ascites due to epithelial cancer: Results of a prospective randomized phase II/III trial. Int J Cancer. 2010;127(9):2209–21.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  110. Sangro B. Data from the third dose cohort of an ongoing study with ADPA2AFP SPEAR T cells. International Liver Congress. 2020;LB012.

Download references


We thank IGR-Curie 1428 Clinical Investigation Center and Labex DCBIOL (ANR-10-IDEX-0001-02 PSL* and ANR-11-LABX0043) for financial support.


Not applicable.

Author information

Authors and Affiliations



JE, RH, AM, and MA performed the literature review, wrote the manuscript, and created the table and figure. All authors approved the final version.

Corresponding author

Correspondence to Marion Alcantara.

Ethics declarations

Ethics approval and consent to participate

Not applicable.

Consent for publication

Not applicable.

Competing interests

JE received honoraria from BMS, MSD, Roche and AstraZeneca. JE received research funding from BMS and Beigene. RH received honoraria from Bristol-Myers Squibb, MSD, Gilead, Kite, Roche, Novartis, Janssen, Celgene, and ADC therapeutics. AM participated in scientific advisory boards for Novartis, BMS, Amgen, Pfizer, Astra Zeneca/Medimmune, Servier, Bayer, Sanofi, Roche, Shattuck Labs, Tessa Therapeutics. AM had teaching/speaker activities for Roche/Genentech, BMS, Astra Zeneca/Medimmune, Amgen, Sanofi, Servier. AM performed scientific & medical consulting for Roche, Bayer, Sanofi/BioNTech, Applied Materials. AM received non-financial support (travel expenses) from Astra Zeneca, BMS, Merck (MSD), Roche. AM received pre-clinical and clinical research grants (institutional funding) from BMS and Sanofi. MA performed scientific & medical consulting for Novartis and Janssen.

Additional information

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated in a credit line to the data.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Edeline, J., Houot, R., Marabelle, A. et al. CAR-T cells and BiTEs in solid tumors: challenges and perspectives. J Hematol Oncol 14, 65 (2021).

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI: