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: 80mg and 160mg/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 +/- 4.7h. Conclusions Enzalutamide 160mg 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.