Nab-Paclitaxel Plus Gemcitabine Vs Gemcitabine Alone for Patients with Metastatic Pancreatic Cancer: Influence of Primary Pancreatic Tumor Location on Efficacy and Treatment Exposure in the Mpact Phase III Trial

Introduction: The prognosis for patients with pancreatic adenocarcinoma is influenced by location of the primary tumor. The primary report of the large phase III MPACT trial revealed superior efficacy for nab-Paclitaxel (nab-P) + gemcitabine (Gem) vs Gem alone as first-line treatment for metastatic pancreatic cancer (PC). This study examined the effect of primary pancreatic tumor location on efficacy and treatment exposure in MPACT. Methods: Previously untreated patients (N = 861) with metastatic PC and baseline bilirubin ≤ upper limit of normal were randomized 1:1 (stratified by performance status, region, and the presence of liver metastases) to receive nab-P 125 mg/m2 + Gem 1000 mg/m2 on days 1, 8, and 15 of each 28-day cycle or Gem 1000 mg/m2 weekly for 7 weeks followed by 1 week of rest (cycle 1) and then days 1, 8, and 15 of each 28-day cycle (cycle ≥ 2). In this analysis, overall survival (OS), progression-free survival (PFS), objective response rate (ORR), and treatment exposure were evaluated according to primary tumor location (head vs other). Results:nab-P + Gem significantly improved OS, PFS, and ORR compared with Gem alone, and these effects were independent of the primary tumor location. Tumor location did not appear to be associated with any differences in treatment exposure (Table). In patients with pancreatic head tumors, the most common grade ≥ 3 adverse events for nab-P + Gem vs Gem alone were neutropenia (35% vs 26%), peripheral neuropathy (21% vs 1%), and fatigue (18% vs 9%); these findings were similar to those in the intent-to-treat (ITT) population. Conclusion:nab-P + Gem demonstrated superior efficacy compared with Gem alone. The improvement in OS, PFS, and ORR with nab-P + Gem treatment vs treatment with Gem remained clinically and statistically significant, independent of the primary tumor location. The findings in this study are consistent with previous efficacy findings in the ITT population from MPACT, and no new safety signals were observed.