Updated Analysis of the MPACT Study in Advanced Pancreatic Cancer Demonstrates Continued Improvement in Survival for Abraxane-based Chemotherapy

A follow up report on the results of the Metastatic Pancreatic Adenocarcinoma Clinical Trial (MPACT) study of Abraxane® (nab-paclitaxel) in combination with Gemzar® (gemcitabine) in previously untreated patients with metastatic pancreatic cancer was presented recently at the annual American Society of Clinical Oncology meeting in Chicago.1 Results of the study were initially reported in the New England Journal of Medicine.2

Pancreatic cancer is one of the deadliest forms of cancer. Each year, approximately 43,000 people are diagnosed with pancreatic cancer in the United States and close to 37,000 die from the disease. The disease is often diagnosed at an advanced stage, and treatment of advanced disease remains challenging.

Gemzar® (gemcitabine) has been a standard chemotherapy drug for the treatment of advanced pancreatic cancer for some time. Abraxane is a novel form of the widely used cancer drug Taxol (paclitaxel). In Abraxane, the paclitaxel is bound to albumin, a human protein in tiny particles. This formulation improves the delivery of the drug directly to cancer cells and reduces side effects.

The study included 861 patients with metastatic pancreatic cancer who were randomized to receive Abraxane plus Gemzar or Gemzar alone. The primary endpoint of the study was overall survival. Results indicated that patients who received Abraxane and Gemzar had a median overall survival of 8.7 months, compared with 6.6 months for those who received Gemzar alone.

What’s more—Abraxane appeared to improve long-term survival, demonstrating a 59 percent increase in one-year survival, with 35 percent of patients alive at one year compared to 22 percent of those who received Gemzar alone. Abraxane doubled the two-year survival rate—10 percent of patients were still alive at two years, compared with 5 percent of those who had Gemzar alone. The extended analysis showed that Abraxane plus Gemzar demonstrated an improvement in the overall survival of patients compared to treatment with Gemzar alone for up to 3.5 years.

Abraxane also improved median progression-free survival. Patients taking Abraxane/Gemzar survived 5.5 months before their disease progressed, compared to 3.7 months in patients who took Gemzar alone. The overall response rate (patients who experienced tumor shrinkage) was 23 percent for Abraxane/Gemzar compared with 7 percent for Gemzar alone.

Abraxane was well tolerated, though did carry a significantly higher incidence of peripheral neuropathy (numbness in the fingers or toes) than Gemzar—17 percent versus less than 1 percent. This led to discontinuation of Abraxane in 8 percent of patients and to dose reduction in 10 percent. In addition, more patients in the Abraxane group experienced neutropenia (38% vs. 27%) and fatigue (17% vs 7%).

The researchers concluded that the combination of Abraxane and Gemzar significantly improved overall survival, progression-free survival, and response rates in patients with metastatic pancreatic cancer; however, the rates of peripheral neuropathy and myelosuppression were increased.

Reference:

1. Goldstein D, El-Maraghi RH, Hammel P, et al. Analyses of updated overall survival (OS) and prognostic effect of neutrophil-to-lymphocyte ratio (NLR) and CA 19-9 from the phase III MPACT study of nab-paclitaxel (nab-P) plus gemcitabine (Gem) versus Gem for patients (pts) with metastatic pancreatic cancer (PC). J Clin Oncol 32:5s, 2014 (suppl; abstr 4027)

2. Von Hoff DD, Ervin T, Arena FP, et al. Increased survival in pancreatic cancer with nab-paclitaxel plus gemcitabine. New England Journal of Medicine. 2013; 369(18): 1691-703.

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