A phase I study of pegylated liposomal doxorubicin and temsirolimus in patients with refractory solid malignancies

This phase I study was an open-labeled, dose escalation study of PLD and T in patients with refractory tumors. The starting dose level (cohort 1) for the study was 30 mg/m² PLD every 4 weeks and 20 mg T weekly (Table 1). A single treatment cycle was defined as 4 weeks, and dose-limiting toxicities (DLTs) were defined during the first cycle only. If none out of three patients in a cohort experienced DLT, then three patients proceeded to the next dose level. If two or more patients experienced DLT, then dose escalation was stopped. If one patient developed DLT, then three more patients entered the same dose level. The maximally tolerated dose (MTD) was defined as one dose level immediately below the dose level at which two patients of a cohort (of 2–6 patients) experienced DLT during the first cycle. Baseline imaging was performed within 28 days prior to starting the study and repeated after every two treatment cycles. Tumor response was assessed by the Response Evaluation Criteria in Solid Tumors (RECIST) 1.0 guidelines. All responses were confirmed by repeat imaging in 4 weeks. Toxicities were graded according to National Cancer institute Common Terminology Criteria for Adverse Events (NCI CTCAE), version 3.0. Hematological DLTs were defined as grade 4 neutropenia of ≥7 days duration, febrile neutropenia of any duration with temperature above 38.5 °C, grade 4 anemia, or grade 4 thrombocytopenia which required transfusion therapy on more than two occasions in 7 days. Non-hematological DLTs were defined as Grade 3 or 4 toxicity with the specific exceptions of nausea, vomiting, or anorexia. Grade 3 triglycerides were only considered a DLT after the administration of appropriate lipid-lowering agents. A delay of treatment for ≥14 days (consecutive or cumulative) prior to beginning cycle 2 was considered a DLT.

Patients were eligible to participate if they had a histological or cytological diagnosis of a malignant solid tumor that had progressed on standard therapies. Eligibility criteria included the following: life expectancy of at least 8 weeks; Eastern Cooperative Oncology Group (ECOG) performance status (PS) ≤2; age ≥18 years; measurable or evaluable disease as defined by RECIST; adequate bone marrow function [absolute neutrophil count (ANC) ≥1,500/mm³, hemoglobin ≥9 g/dL, and platelet count ≥100,000/mm³], adequate renal function (serum creatinine ≤2.0 mg/dL or creatinine clearance ≥60 ml/min/1.73²); adequate hepatic function [aspartate aminotransferase (AST), alanine aminotransferase (ALT) level, alkaline phosphatase ≤2.5× institutional upper limit of normal (ULN), and total bilirubin level ≤1.5 × ULN]; fasting cholesterol level ≤350 mg/dL; fasting triglyceride ≤400 mg/dL; albumin <3 mg/dL; and no active central nervous system (CNS) metastases, and normal left ventricular ejection fraction (LVEF ≥ 50 %) by multigated acquisition scan (MUGA). Patients may not have had chemotherapy or radiotherapy within 4 weeks of starting the protocol treatment. Patients must have provided signed and dated informed consent forms approved by the Washington University Human Research Protection Office (HRPO). All patients who received at least one treatment were included in the safety analysis. The study was conducted under the auspices of the Siteman Cancer Center Quality Assurance and Safety Monitoring Committee.

Patients received PLD intravenously once every 4 weeks and T by intravenous infusion weekly. No treatment cycle was started until ANC ≥1,500/mm³, the platelets count ≥100,000/mm³, hemoglobin ≥9.0 g/dL, and all other treatment-related toxicities were grade ≤1. If, after the appropriate dose reductions, a treatment-related toxicity required a delay of ≥14 days before starting subsequent cycles, the patient was taken off study. If any grade ≥2 neutropenia or thrombocytopenia occurred at the start of a cycle, administration of both PLD and T was delayed (no more than 14 days) until the toxicity resolved to grade 1 or less. For patients experiencing toxicities, in subsequent cycles, PLD was given at a lower dose level while T could be resumed at the prior dose level or a reduced dose level at the discretion of the treating physician. For any occurrences of neutropenic fever, administration of either both drugs (at the start of a cycle) or T (during a cycle) was delayed until it resolved to grade ≤1 and then both drugs were reduced by one dose level. Once the dose was reduced for a subject, all subsequent cycles for PLD were administered at the reduced dose.

If grade ≥2 stomatitis/mucositis persisted at the start of a cycle, administration of both drugs was delayed until the toxicity resolved to grade ≤1, and the drug deemed responsible for the stomatitis/mucositis was reduced by one dose level in the current and subsequent cycles. If neither drug was identified as being responsible for the adverse events, then both drugs were reduced by one dose level. If grade ≥2 stomatitis/mucositis occurred during the weeks 2–4 of a cycle, T was omitted from the regimen until the stomatitis/mucositis resolved to grade ≤1; then, the drug deemed responsible for the adverse event was reduced in the current and subsequent cycles.

The PK of doxorubicin were assessed by analyzing the concentrations of doxorubicin in plasma samples collected at 0 (pre-dose), 0.5, 1.5, and 5 h after the start of drug infusion and approximately 48, 96, and 168 h post-infusion. Plasma concentrations of doxorubicin were analyzed using a liquid chromatography mass spectrometry analytical method (detailed description of bioanalytical methods provided in supplementary materials). The PK parameters were estimated using non-compartmental methods. The area under the concentration–time curve from time 0 to the last sampling point (AUC_last) was calculated using the linear trapezoidal method. The remaining area under the curve from the last time point to infinity was calculated using the equation AUC_last−∞ = C _last/k _el, where C _last is the last-measured plasma concentration and k _el is the slope of the concentration versus time plot during the log-linear terminal phase. Total clearance (CL) and elimination half-life (t _1/2) were calculated as follows: CL = dose/AUC, t _1/2 = 0.693/k _el.

The primary outcome of this study was assessment of toxicity. The results are summarized by simple descriptive summary statistics. The PK variables for doxorubicin obtained using non-compartmental methods are summarized using mean ± standard deviations.