Phase 1b study of a small molecule antagonist of human chemokine (C-C motif) receptor 2 (PF-04136309) in combination with nab-paclitaxel/gemcitabine in first-line treatment of metastatic pancreatic ductal adenocarcinoma.

Background In pancreatic ductal adenocarcinoma (PDAC), the chemokine (C-C motif) ligand 2 (CCL2)/chemokine (C-C motif) receptor 2 (CCR2) axis plays a key role in immunosuppressive properties of the tumor microenvironment, patient prognosis, and chemoresistance. This phase Ib study assessed the effects of the orally administered CCR2 inhibitor PF-04136309 in combination with nab-paclitaxel and gemcitabine in patients with previously untreated metastatic PDAC. Methods Patients received PF-04136309 twice daily (BID) continuously plus nab-paclitaxel (125 mg/m2) and gemcitabine (1000 mg/m2) administered on days 1, 8, and 15 of each 28-day cycle. The primary objectives were to evaluate safety and tolerability, characterize dose-limiting toxicities (DLTs), and determine the recommended phase II dose (RP2D) of PF-04136309. Results In all, 21 patients received PF-04136309 at a starting dose of 500 mg or 750 mg BID. The RP2D was identified to be 500 mg BID. Of 17 patients treated at the 500 mg BID starting dose, three (17.6%) experienced a total of four DLTs, including grade 3 dysesthesia, diarrhea, and hypokalemia and one event of grade 4 hypoxia. Relative to the small number of patients (n = 21), a high incidence (24%) of pulmonary toxicity was observed in this study. The objective response rate for 21 patients was 23.8% (95% confidence interval: 8.2-47.2%). Levels of CD14 + CCR2+ inflammatory monocytes (IM) decreased in the peripheral blood, but did not accumulate in the bone marrow. Conclusions PF-04136309 in combination with nab-paclitaxel plus gemcitabine had a safety profile that raises concern for synergistic pulmonary toxicity and did not show an efficacy signal above nab-paclitaxel and gemcitabine. ClinicalTrials.gov identifier: NCT02732938.

First-in-human trial of an anti-5T4 antibody-monomethylauristatin conjugate, PF-06263507, in patients with advanced solid tumors.

Background The antibody-drug conjugate PF-06263507 targets the cell-surface, tumor-associated antigen 5T4 and consists of a humanized IgG1 conjugated to the microtubule-disrupting agent monomethylauristatin-F by a non-cleavable maleimidocaproyl linker. In this first-in-human, dose-finding trial (NCT01891669), we evaluated safety, pharmacokinetics, and preliminary antitumor activity of PF-06263507 in pretreated patients with advanced solid tumors, unselected for 5T4 expression. starting at 0.05 mg/kg, with 25, 56, and 95% dose increments, depending on observed dose-limiting toxicities (DLTs), applying a modified continual reassessment method. Results Twenty-six patients received PF-06263507 at 0.05 to 6.5 mg/kg. The first DLT, grade 3 photophobia, occurred at 4.34 mg/kg and two additional DLTs, grade 2 keratitis and grade 1 limbal stem cell deficiency (> 2-week dosing delay), at 6.5 mg/kg. The most common adverse events (AEs) were fatigue (38.5%), photophobia (26.9%), and decreased appetite, dry eye, nausea, and thrombocytopenia (23.1% each). No treatment-related grade 4-5 AEs were reported. Systemic exposure of PF-06263507 increased in a dose-related manner. At the maximum tolerated dose (MTD, 4.34 mg/kg), mean terminal half-life for PF-06263507 and unconjugated payload were ~6 and 3 days, respectively. Payload serum concentrations were substantially lower compared with PF-06263507. No objective responses were observed. Conclusions The MTD and recommended phase II dose were determined to be 4.34 mg/kg. Ocular toxicities accounted for the DLTs observed, as previously reported with monomethylauristatin-F payloads. Further studies are warranted to investigate clinical activity of this agent in patients with 5T4-expressing tumors.Trial registration ID: NCT01891669.