Patients with advanced solid tumors were screened and enrolled in the study conducted at the First Hospital of Jilin University, China. The eligibility criteria were: pathologically or cytologically confirmed advanced solid tumor that had failed to respond to or was not suitable for standard therapeutic regimens; age range, 18–75 years with a body mass index of 18–30 kg/m2; at least one measurable lesion per the Response Evaluation Criteria In Solid Tumors (RECIST) (version 1.1); at least a 3-month life expectancy, and an Eastern Cooperative Oncology Group (ECOG) performance score of 0–2; and remission of previous treatment-related adverse events (AEs) of Grade ≤ 1 according to the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE version 4.0). The exclusion criteria were: treatment with any other anti-tumor therapy within 4 weeks before study entry; prior Grade ≥ 3 adverse reactions related to an EGFR TKI; symptomatic central nervous system metastasis; clinically significant arrhythmia or left ventricular ejection fraction (LVEF < 45%); accompanying disease affecting gastrointestinal absorption; hepatitis B virus (HBV), hepatitis C virus (HCV) or human immunodeficiency virus (HIV) infection; pregnancy or breastfeeding; and any other uncontrolled disease of the respiratory, circulatory, endocrine, or urinary systems. The study was approved by the ethics committee of the First Hospital of Jilin University and conducted under the guidelines of the Declaration of Helsinki and the Principles of Good Clinical Practice. Written informed consent was obtained from all patients or their legal representatives prior to their enrollment.
This was a phase I, single-center, open-label, dose-escalation study conducted at First Hospital of Jilin University, China (registration no.: ChiCTR-OPC-15007153 registered 28 September 2015 at http://www.chictr.org.cn). Larotinib mesylate capsules were produced and supplied by Sunshine Lake Pharma Co., Ltd. (Guangdong Province, China) in different unit doses of 10, 50, and 150 mg. Seven dose levels were designed in the study: 50, 100, 150, 220, 300, 350, and 400 mg with administration stages labeled cycle 0, cycle 1, and subsequent treatment cycles. Patients received an oral single dose of larotinib mesylate after fasting during a 6-day cycle 0 to evaluate the tolerance and pharmacokinetic characteristics. After cycle 0, larotinib mesylate was continuously administered once daily for 28 days in cycle 1, and the tolerance and pharmacokinetic characteristics of multiple doses were evaluated. The patients who experienced dose-limiting toxicities (DLTs) and disease control (complete response [CR], partial response [PR], or stable disease [SD]) at the end of cycle 1 were permitted to participate in the subsequent 28-day treatment cycles until progressive disease (PD) or intolerance was observed.
We enrolled 3–6 patients for each dose level, with the goal of having at least 3 patients complete the cycle 0 and cycle 1 treatments. If a patient experienced a DLT in cycle 0 or cycle 1, expansion to 6 patients was required for the current dose level. If two or more DLTs were observed in those six patients, dose escalation would be stopped.
DLTs were observed according to the NCI CTCAE version 4.03 and defined as the emergence of any of the following drug-related AEs: hematological toxicity including Grade ≥ 3 neutropenia or thrombocytopenia and other Grade ≥ 4 hematological toxicity; nonhematological toxicities including Grade ≥ 2 atrioventricular block or renal injury; Grade ≥ 2 nausea, emesis, or diarrhea for ≥ 7 days despite optimal treatment; Grade ≥ 3 nausea, emesis, diarrhea, or rash despite supportive care; and alanine aminotransferase (ALT) or aspartate aminotransferase (AST) elevation by more than 5 times the upper limits of normal for ≥ 7 days and other Grade ≥ 3 nonhematological toxicities.
The primary endpoints of the study were metrics of safety and tolerance, as determined by the observance of DLTs and MTDs as well as the recommended doses and regimens for subsequent clinical trials of larotinib mesylate. The secondary endpoints included the pharmacokinetic characteristics and preliminary antitumor activity of larotinib mesylate according to RECIST version 1.1. The exploratory endpoints were the abilities of biomarkers to predict the antitumor effect of larotinib mesylate in patients with solid tumors.
Safety and tolerance analyses
Safety was assessed according to the NCI CTCAE version 4.03 including AEs, vital signs, and results from 12-lead echocardiogram, cardiac ultrasound, physical examination, ophthalmic testing, and clinical laboratory tests. Dosage adjustments could be applied from cycle 2 according to the severity of the toxicities. Drug administration would be suspended when drug-related AEs were graded at 3 or 4, and the original dose or reduction dose would be given if the AEs returned to baseline or Grade 1 (nonhematological toxicities)/grade 2 (hematological toxicities) within 14 days.
Pharmacokinetics sampling and analysis
Blood samples (4 mL) for pharmacokinetic analyses were collected in tubes containing K2EDTA anticoagulant. The sampling time-points included before dosing and 1, 2, 3, 4, 5, 6, 9, 12, 24, 36, 48, 72, 96 and 120 h post-dosing on cycle 0 day 1 and cycle 1 day 28; as well as 0 h (pre-dose) on cycle 1 days 8, 15, and 22. Blood samples were centrifuged at 3,000 rpm for 10 min at 4 °C and stored at − 80 °C until liquid chromatography-mass spectrophotometry (LC-MS/MS) analysis. Urine and fecal samples were collected only when patients were given the 150-mg and 220-mg dose levels at sampling time intervals of 0–4, 4–8, 8–12, 12–24, 24–48, 48–72, 72–96 and 96–120 h in cycle 0.
Plasma pharmacokinetic data (larotinib and major metabolite M5) were analyzed by standard non-compartmental methods using WinNonlin version 7.0 (Certara USA, Inc.) for calculation of pharmacokinetic parameters including peak plasma concentration (Cmax), time to peak plasma concentration (Tmax), area under the plasma concentration–time curve from time 0 to 24 h (AUC0 − 24), AUC from time 0 to the last measurable concentration timepoint before the next dose (AUC0 − t), AUC from time 0 to infinity (AUC0−∞), terminal elimination half-life (t1/2), clearance (CL/F), apparent volume of distribution (Vz/F) at the first dose, and these parameters at steady state (Css,max, Css, min, Tss, max, AUCss, 0−24, AUCss, 0−t, AUCss, 0− ∞, CL/Fss and Vz/Fss). For urine and fecal data, the accumulative excretion rates of larotinib and M5 were calculated.
Tumor evaluation was performed at screening, the end of cycle 1, and every two cycles of subsequent treatment according to RECIST version 1.1. The disease control rate (DCR) (including CR, PR and SD), objective remission rate (ORR) (including CR and PR), and progression-free survival (PFS) were also evaluated.
Concomitant medications could be given when clinically required. No other anti-tumor therapies were permitted during the study, and drugs that can cause a prolonged QT interval were also prohibited. Inhibitors and inducers of CYP3A4 were to be used with caution, because around 85% of larotinib mesylate was found to be metabolized by CYP3A4 in in vitro studies (data not published).
Statistical analyses were performed using SAS software, version 9.2 (SAS Institute Inc., USA). Descriptive statistics were used to summarize continuous variables as cases, means with standard deviations (SDs), medians, quartiles, maximums and minimums. For categorical variables, frequencies and percentages were used. A linear mixed effects model, relating log-transformed Cmax and AUC parameters to log-transformed dose, was used to investigate dose proportionality.