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.

Randomized phase II study of bevacizumab in combination with chemotherapy in previously untreated extensive-stage small-cell lung cancer: results from the SALUTE trial.

PURPOSE: Because of promising efficacy signals in single-arm studies, a placebo-controlled, double-blind, randomized phase II trial was designed to assess the efficacy and safety of adding bevacizumab to first-line standard chemotherapy for treatment of extensive-stage small-cell lung cancer (SCLC). PATIENTS AND METHODS: Patients with SCLC were randomly assigned to receive bevacizumab or placebo, with cisplatin or carboplatin plus etoposide, for four cycles followed by single-agent bevacizumab or placebo until progression or unacceptable toxicity. The primary end point was progression-free survival (PFS). RESULTS: Fifty-two patients were randomly assigned to the bevacizumab group and 50 to the placebo group; 69% versus 66%, respectively, completed four cycles of therapy. Median PFS was higher in the bevacizumab group (5.5 months) than in the placebo group (4.4 months; hazard ratio [HR], 0.53; 95% CI, 0.32 to 0.86). Median overall survival (OS) was similar for both groups (9.4 v 10.9 months for bevacizumab and placebo groups, respectively), with an HR of 1.16 (95% CI, 0.66 to 2.04). Overall response rates were 58% (95% CI, 43% to 71%) for the bevacizumab group and 48% (95% CI, 34% to 62%) for the placebo group. Median duration of response was 4.7 months for the bevacizumab group and 3.2 months for the placebo group. In the bevacizumab and placebo groups, 75% versus 60% of patients, respectively, experienced one or more grade 3 or higher adverse events. No new or unexpected safety signals for bevacizumab were observed. CONCLUSION: The addition of bevacizumab to cisplatin or carboplatin plus etoposide for treatment of extensive-stage SCLC improved PFS, with an acceptable toxicity profile. However, no improvement in OS was observed.

Phase II study of picoplatin as second-line therapy for patients with small-cell lung cancer.

PURPOSE: This study was designed to confirm the efficacy and safety of picoplatin, a cisplatin analog designed to overcome platinum resistance, in patients with small-cell lung cancer (SCLC) with platinum-refractory/-resistant disease. PATIENTS AND METHODS: All patients received intravenous picoplatin 150 mg/m(2) every 3 weeks. Tumor response, progression-free survival, and overall survival were evaluated. Adverse events were assessed for frequency, severity, and relationship to treatment. Quality of life was assessed with the Lung Cancer Symptom Scale instrument. RESULTS: Seventy-seven patients were treated with picoplatin (median number of cycles, two; range one to 10). Three patients (4%) had a partial response, 33 (43%) had stable disease (four of these were unconfirmed partial responses), 36 (47%) had progressive disease, and five were not assessable for response. Median progression-free survival was 9.1 weeks (95% CI, 7.0 to 12.1 weeks). Median overall survival was 26.9 weeks (95% CI, 21.1 to 33.4). The most common grade 3 and 4 toxicities were thrombocytopenia (48%), neutropenia (25%), and anemia (20%). The most commonly reported adverse events of any severity included thrombocytopenia (64%), anemia (49%), neutropenia (39%), nausea (27%), fatigue (16%), and dyspnea (16%). No severe neurotoxicity or nephrotoxicity were observed. There were no treatment-related deaths. CONCLUSION: Picoplatin demonstrated clinical efficacy in platinum-refractory SCLC. The major toxicity was hematologic. These results warrant further evaluation in this patient population.