Eligible patients were aged 18–75 years with histologically or cytopathologically confirmed advanced solid tumors. Patients had to either be refractory to, or intolerant of standard treatment known to provide clinical benefit for their metastatic cancers, or to be unable to afford them. The other inclusion criteria were as follows: Eastern Cooperative Oncology Group (ECOG) performance status of 0–2; adequate hematology (absolute neutrophil count ≥ 1.5 × 109/L, platelet count ≥ 80 × 109/L, hemoglobin ≥ 9 g/dL); normal liver function (serum bilirubin ≤ 1.5 × upper limit of normal [ULN]; aspartate aminotransferase and alanine aminotransferase ≤ 2.5 × ULN, except in patients with liver metastases) and kidney function (serum creatinine ≤ 1.5 × ULN); at least one measurable disease according to the Response Evaluation Criteria in Solid Tumors (RECIST) 1.0; life expectancy of ≥ 3 months; and no anticancer treatment for at least 4 weeks prior to enrollment in the study.
Exclusion criteria included the following: pregnant or breast feeding patients, any clinically significant gastrointestinal abnormalities that influence oral administration, uncontrolled or significant cardiovascular disease, left ventricular ejection fraction (LVEF) < 40%, metastases to the central nervous system (symptomatic and/or requiring treatment), active serious infection, and bleeding diathesis or coagulopathy.
Study design and treatment
This was the first-in-human phase I dose-escalation study of AST1306 for patients with advanced solid tumors. AST1306 was orally administered without food for one day followed by two days off to evaluate single dose PK profiles. After that, it was continuously administered for 21 days and two days off to assess multiple dose PK profiles and safety. Once daily in two dose levels (400 mg QD and 800 mg QD) was first explored and according to the PK profile, with shorter t1/2 of 3–5 hours, twice daily in five dose levels (600 mg BID, 800 mg BID, 1000 mg BID, 1200 mg BID and 1500 mg BID) were then investigated. Three times daily in three dose levels (800 mg TID, 1000 mg TID and 1200 mg TID) were explored subsequently. Treatment was then repeated at the same dose level in 28-day cycles until unacceptable toxicities, disease progression or the patient’s withdrew from the study. PK extension study was performed to enroll additional patients up to at least eight patients per dose cohort in three dose levels (MTD, one or two doses level lower than the MTD) for further evaluation of PK profiles.
For the food-effect study, an open, two-way crossover design was adopted to assess the effect of food on the oral bioavailability of AST1306 at the MTD dose level (Additional file 1: Figure S1). On day 1, 6 subjects were fasted and 6 were fed, and all 12 subjects received a single dose of AST1306. Following a 2-day washout period, subjects from the fasted group were fed and vice versa. On “fasting” days (day 1 or 4), subjects were required to fast for a minimum of 2 h prior to dosing, and for at least 1 h post-dosing. On “fed” days (day 1 or 4), subjects were fasted overnight and were required to ingest a standard high-fat breakfast within 30 min prior to dosing. PK sampling then took place on day 1 and day 4. The PK sampling time points were pre-dose, 0.5, 1, 1.5, 2, 2.5, 3, 4, 6, 8, 12, and 24 hours after dosing.
This study was conducted in compliance with the ethical principles derived from the Declaration of Helsinki and all the International Conference on Harmonization (ICH) Good Clinical Practice (GCP) guidelines. The protocol, all the amendments and informed consent documentations were reviewed and approved by the Institutional Review Board at Fudan University Shanghai Cancer Center. All patients provided written, signed informed consent prior to entry into the trial.
Dose escalation and safety assessment
Safety and tolerability were evaluated and assessed by investigators throughout the study and up to 14 days after the final dose of AST1306 according to Common Terminology Criteria for Adverse Events (CTC-AE) version 4.03. Laboratory evaluations and electrocardiogram were conducted at screening; every week of first and second cycles; every two weeks of third cycle and every four weeks of subsequent cycles. AEs assessment, vital signs, physical examinations and echocardiography were performed.
A modified Fibonacci 3 plus 3 dose-escalation design was employed. Tolerability was evaluated according to the type and frequency of DLTs observed from single-day-dose administration until day 21 of the first cycle of continuous dosing. DLTs were defined as follows: grade ≥ 3 non-hematologic toxicity (except nausea, vomiting and diarrhea); grade ≥ 3 nausea, vomiting or diarrhea uncontrollable with standard supportive care; grade 4 neutropenia or febrile neutropenia; and grade 4 thrombocytopenia or bleeding requiring a platelet transfusion. If two or more patients experienced DLTs in three to six patients for each cohort, dose escalation was terminated and the dose level below was defined as the MTD.
Dose interruptions were permitted for no more than 14 days for patients experiencing DLTs in the first cycle or intolerable toxicities in the subsequent cycles, with treatment resumed at the next lower dose level upon adequate recovery (grade ≤ 1). More than two dose level reductions were not allowed.
Patients in the PK extension study and food-effect study were also included to evaluate safety further.
Evaluation of antitumor activity
Antitumor activity was assessed by tumor measurements according to RECIST 1.0 and performed at 8-week intervals. The primary efficacy endpoint was progression free survival (PFS), which was defined as the time from the first administration until disease progression or death. Overall survival (OS) and response rate were also assessed. Clinical benefit rate was measured and defined as the proportion of patients with complete response, partial response and stable disease (SD) ≥ 6 months.
All PK sampling was performed in the first cycle. Plasma concentrations of AST1306 single-day dosing were determined at the following distinct time points: pre-dose, 0.5 h, 1 h, 1.5 h, 2 h, 3 h, 4 h, 6 h, 8 h, 10 h, 12 h, 24 h, 36 h, and 48 h after the single dose administration in the 400 mg QD and 800 mg QD dose cohorts. For the next five dose cohorts with twice daily (once every 12 hours) administration, the time points of plasma sample collection were as follows: pre-dose, 0.5 h, 1 h, 1.5 h, 2 h, 3 h, 4 h, 6 h, 8 h, and 12 h after the first dose administration, and pre-dose, 1 h, 2 h, 3 h, 4 h, 6 h, 8 h, 12 h, and 24 h after the second dose administration. Three dose cohorts with three times daily (once every 8 hours) administration were further investigated with distinct time points for plasma collecting (pre-dose, 0.5 h, 1 h, 1.5 h, 2 h, 3 h, 4 h, 6 h, and 8 h after the first dose administration; 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, and 8 h after the second dose administration; 1 h, 2 h, 3 h, 4 h, 8 h, 12 h, 24 h, and 36 h after the third dose administration). PK parameters of AST1306 were also determined on days 10, 23 (pre-dose and 2 h after the first dosing), and 24 (steady state, the same time points as the first-day dosing) of continuous treatment. The PK sampling schedule for the PK extension phase was totally the same as that for the dose escalation study.
PK analysis was conducted using Phoenix WinNonlin® software (version 6.1, Pharsight, Mountainview, CA). Standard non-compartmental methods were used to calculate the area under the plasma concentration-time curve over the time interval from 0 to 24 h (AUC0–24,ss), maximum measured concentration of the analyte in plasma (Cmax), and terminal half-life of the analyte in plasma (t1/2). Time from dosing to the maximum concentration of the analyte in plasma (tmax,) was reported as a median value. The concentration at the trough level was determined using the concentration at 24 h (C24) on steady state days.
The power model method was used to assess the dose proportionality. The differences between fed and fasting conditions were assessed by ANOVA, and 90% confidence intervals for ratios were given.