Phase 1 trial of enzalutamide in combination with gemcitabine and nab-paclitaxel for the treatment of advanced pancreatic cancer

Background Androgens were shown to play a key role in the growth and progression of pancreatic cancer. We evaluated the safety and tolerability of the combination of enzalutamide, a novel androgen receptor (AR) antagonist with gemcitabine and nab-paclitaxel as a first-line treatment in advanced pancreatic cancer. Methods We used the standard 3 + 3 dose escalation design with cohort expansion to evaluate 2 dose levels of enzalutamide: 80 mg and 160 mg/day orally (phase 1a) in combination with gemcitabine and nab-paclitaxel in metastatic pancreatic cancer patients. In the expansion phase (phase 1b), AR+ was a pre-requisite criterion. We also evaluated the full pharmacokinetic (PK) profile for nab-paclitaxel and enzalutamide. Results We enrolled 24 patients, 12 patients in phase 1a and 12 patients in phase 1b. The median age was 68 (range, 32–84) years. No DLTs were observed. Grade 3/4 treatment related adverse events included neutropenia (44%), anemia (40%), leukopenia (24%), nausea and vomiting (20%), diarrhea (16%), infections (12%), thrombocytopenia (8%), thromboembolic event (8%), hypertension (8%), hypokalemia (8%), hyponatremia (8%), and ALT elevation (8%). Median overall survival and progression-free survival was 9.73 [95%CI:9.73–13.5] and 7.53 (95%CI:6.05–12.8) months, respectively. PK analysis suggests that the combination therapy does not impact the kinetics of either drug evaluated. Enzalutamide reached steady-state levels between day 22 and 29 and the mean half-life of nab-paclitaxel was 19.6 ± 4.7 h. Conclusions Enzalutamide 160 mg daily in combination with gemcitabine and nab-paclitaxel can be safely administered with no unexpected toxicities. We also noticed preliminary signals of efficacy with this combination.