Phase Ib study of the combination of pexidartinib (PLX3397), a CSF-1R inhibitor, and paclitaxel in patients with advanced solid tumors.

PURPOSE: To evaluate the safety, recommended phase II dose (RP2D) and efficacy of pexidartinib, a colony stimulating factor receptor 1 (CSF-1R) inhibitor, in combination with weekly paclitaxel in patients with advanced solid tumors. PATIENTS AND METHODS: In part 1 of this phase Ib study, 24 patients with advanced solid tumors received escalating doses of pexidartinib with weekly paclitaxel (80 mg/m2). Pexidartinib was administered at 600 mg/day in cohort 1. For subsequent cohorts, the dose was increased by ⩽50% using a standard 3+3 design. In part 2, 30 patients with metastatic solid tumors were enrolled to examine safety, tolerability and efficacy of the RP2D. Pharmacokinetics and biomarkers were also assessed. RESULTS: A total of 51 patients reported ≥1 adverse event(s) (AEs) that were at least possibly related to either study drug. Grade 3-4 AEs, including anemia (26%), neutropenia (22%), lymphopenia (19%), fatigue (15%), and hypertension (11%), were recorded in 38 patients (70%). In part 1, no maximum tolerated dose was achieved and 1600 mg/day was determined to be the RP2D. Of 38 patients evaluable for efficacy, 1 (3%) had complete response, 5 (13%) partial response, 13 (34%) stable disease, and 17 (45%) progressive disease. No drug-drug interactions were found. Plasma CSF-1 levels increased 1.6- to 53-fold, and CD14dim/CD16+ monocyte levels decreased by 57-100%. CONCLUSIONS: The combination of pexidartinib and paclitaxel was generally well tolerated. RP2D for pexidartinib was 1600 mg/day. Pexidartinib blocked CSF-1R signaling, indicating potential for mitigating macrophage tumor infiltration.

A Phase I study of the combination of oxaliplatin/docetaxel and vandetanib for the treatment of advanced gastroesophageal cancer.

INTRODUCTION: This study aimed to assess the safety and tolerability of the multitargeted tyrosine kinase inhibitor, vandetanib (V), in combination with two chemotherapeutic agents, oxaliplatin (O) and docetaxel (D) in advanced gastroesophageal (GE) cancer. METHODS: This was a Phase I study (NCT00732745) with a standard 3+3 dose escalation design. The primary aim was to determine the optimal dose of the combination of vandetanib and OD chemotherapy. RESULTS: Initial treatment for the first cohort consisted of oxaliplatin at 100 mg/m2 on day 1, docetaxel at 35 mg/m2 on days 1 and 8 and vandetanib 100 mg PO daily of 21-day treatment cycles. As dose limiting toxicity (DLT) was reached in 2 out of 3 patients in cohort 1 (one grade 3 and one grade 4 diarrhea with dehydration), 6 patients were treated then at dose level -1 (O 80 mg/m2 on day 1, D 30 mg/m2 on days 1 and 8, V 100 mg PO daily days 1-21) in which no further DLTs were observed. This dose was established as maximum tolerated dose and is the recommended phase 2 dose. 8 out of 9 enrolled patients had adenocarcinoma. At dose level 1, 1 of the 3 patients had a documented partial response and 2 patients had stable disease. At dose level -1, 1 of 6 patients achieved a complete response, 2 of 6 patients had stable disease, and 3 of 6 patients had progressive disease. CONCLUSIONS: Vandetanib added to oxaliplatin and docetaxel showed manageable toxicity and limited activity in advanced GE cancer.

Phase I trial of pomalidomide given for patients with advanced solid tumors.

PURPOSE: To determine the safety, the maximal tolerated dose, and to assess for any clinical activity of pomalidomide given to patients with advanced solid tumors. PATIENTS AND METHODS: Patients with incurable solid tumors were enrolled. Two different dosing schedules were explored. In Cohort A patients were given pomalidomide once daily for 21 days followed by a 7 day rest. For Cohort B additional patients were recruited to receive pomalidomide given once daily for 28 consecutive days. Dose-limiting toxicity was defined as ≥grade 3 non-hematological toxicity that occurs during cycle 1 and that does not resolve to ≤grade 1 by day 35. Subjects must have received optimal symptomatic treatment for ≥grade 3 nausea, vomiting, or diarrhea to be considered a DLT. Grade 4 transaminitis was considered to be a DLT while grade 3 transaminitis must be present >7 days to be a DLT. Grade 3 febrile neutropenia was considered a DLT. Grade 4 neutropenia, without a fever, was a DLT if the neutropenia did not improve to ≤grade 1 by day 35 of cycle one. Platelet count ≤25,000/mm(3) must improve to ≥75,000/mm(3) by day 35 of cycle one in order not to be considered a DLT. If a patient did not complete one cycle of therapy, for reasons other than a DLT, a replacement subject was added to the same cohort level. RESULTS: A total of 40 patients were enrolled. In Cohort A, three patients received pomalidomide at 5 mg daily without any significant toxicity. Two patients in the 10 mg cohort experienced dose-limiting toxicities of two episodes of grade 3 dyspnea and one grade 4 neutropenia. Six patients were then enrolled at the 7 mg daily of pomalidomide, and no dose-limiting events were observed. In Cohort B, 29 patients were enrolled and the maximal tolerated dose was 4 mg once daily. Stable disease in a variety of tumors was observed. CONCLUSIONS: Pomalidomide was well tolerated and the recommended phase II dosing schedules are 7 mg daily given for 21 days followed by a 7-day rest or pomalidomide 4 mg given on an uninterrupted daily schedule.