Amgen Announces Pivotal Phase 3 Results Demonstrating Panitumumab's Efficacy in Metastatic Colorectal Cancer

Strategic Insights -

Amgen today announced pivotal Phase 3 results demonstrating that panitumumab significantly improved progression-free survival and disease control in metastatic colorectal cancer patients who had failed standard chemotherapy. The results were presented at the 97th Annual Meeting of the American Association for Cancer Research. Panitumumab reduced the rate of disease progression by approximately half compared to best supportive care alone in these heavily pre-treated patients.

Key Takeaways:

  • Panitumumab significantly improved progression-free survival by 46% compared to best supportive care alone (p less than 0.000 000 001).
  • Patients treated with panitumumab showed a 46% decrease in tumor progression rate versus those who received best supportive care alone.
  • Approximately four times as many panitumumab-treated patients were alive and progression-free at six months (18% vs. 5% with BSC alone).
  • Twice as many panitumumab-treated patients were alive and progression-free at week 32 (10% vs. 4% with BSC alone).
  • Panitumumab significantly improved disease control compared to best supportive care alone, with a response rate of 8% vs. 0% and a stable disease rate of 28% vs. 10%.
  • Approximately 75% of BSC patients entered a cross-over arm to receive panitumumab after their disease had progressed, showing a 9% partial response and 32% stable disease.
  • Panitumumab treatment had a low incidence of infusion reactions (1%) and no grade 3 or 4 infusion reactions were reported.
  • Panitumumab was shown to improve progression-free survival and response rate regardless of the level or intensity of EGFr staining.
  • Improvements in progression-free survival and disease control also occurred regardless of age, sex, primary tumor location, or performance status.

Statistics:

  • 463 patients with metastatic colorectal cancer who had failed standard chemotherapy were randomized to receive panitumumab plus BSC (n=231) every two weeks or BSC alone (n=232).
  • Panitumumab was shown to reduce the rate of disease progression by approximately half (46%) compared to best supportive care alone (p less than 0.000 000 001).
  • Approximately 75% of BSC patients entered a cross-over arm to receive panitumumab after their disease had progressed.
  • The incidence of infusion reactions with panitumumab was low (1%) and no grade 3 or 4 infusion reactions were reported.

Sources:

  • Amgen press release, April 3, 2006.
  • Abstract #CP-1, 97th Annual Meeting of the American Association for Cancer Research.
  • Amgen Form 10-K for the year ended December 31, 2005.
  • Amgen's periodic reports on Form 10-Q and Form 8-K.