P-0229 - Efficacy of chemotherapy after treatment with regorafenib in metastatic colorectal cancer (mCRC)

Date 28 June 2014
Event World GI 2014
Session Poster Session
Topics Anti-Cancer Agents & Biologic Therapy
Colon Cancer
Rectal Cancer
Presenter Ryan Wilcox
Citation Annals of Oncology (2014) 25 (suppl_2): ii14-ii104. 10.1093/annonc/mdu165
Authors R. Wilcox1, J. Hubbard1, A. Pham1, J. Quevedo1, H. Yoon1, S. Robinson1, A. Grothey2, M. Kidd1, S. Alberts1, J. Rubin1, M. Hartgers1, J. Mitchell1
  • 1Mayo Clinic, Rochester/US
  • 2Mayo Clinic College of Medicine, Division of Medical Oncology, Rochester/US

Abstract

Introduction

Improvements in outcome of medical therapy for mCRC are closely linked to the availability of active agents in this disease. Based on phase III clinical data, regorafenib, a multikinase inhibitor, was approved September 2012 by the FDA for patients with mCRC who have been previously treated with all approved therapies. Treatment options after regorafenib salvage therapy have not been established. Based on clinical observations, we performed a hypothesis generating retrospective case series review to assess chemotherapy response in mCRC after regorafenib therapy.

Methods

After IRB approval, all records at Mayo Clinic from April 2010 to February 2014 were reviewed for use of regorafenib and subsequent outcomes for mCRC. Patient and tumor characteristics including duration of all therapies prior to and after treatment with regorafenib were reviewed. Response and progression were determined by investigators' reviews of charts and imaging. Kaplan-Meier method was used to calculate time to event and survival analysis.

Results

Regorafenib was given to 59 patients with mCRC, and of these, 3 (5%) continued on regorafenib at the time of analysis and 37 (63%) had no additional therapy. Post-regorafenib therapy was given to 19 (32%) patients, and of these, 2 went on a clinic trial with PD as best response. 17 patients were treated with standard approved therapy of which 3 (18%) progressed and 14 (82%) showed response or SD, with mTTP 4.5 mo. (CI 2.0 - 5.6). Out of the 17 treated with standard agents, 6 (35%) had stable disease or response to previous therapy that had previously been discontinued without definitive progression, whereas 2 (12%) responded to rechallenge with chemotherapy that was previously discontinued due to PD. Response was also noted in 6 (35%) patients that received an agent not given prior to regorafenib (most commonly panitumumab and ziv-aflibercept). For those treated with standard therapy, a median of 4 (range 1-9) therapies were given prior to regorafenib. After discontinuation of regorafenib, median of 1 (range 1 - 4) therapies were given, mOS was not reached with a median follow up of 8.5 mo (CI 3.5 – 9.4). Probability of survival at 3, 6, and 12 months after discontinuation of regorafenib was 91%, 82% and 68% respectively.

Conclusion

Re-utilizing approved treatment options after regorafenib may be beneficial in patients with mCRC including in patients with progression on identical therapy before regorafenib. The outcomes seen in our review are likely influenced by including a select group of patients who were candidates for therapy after regorafenib. Analysis of additional patient cases in a multi-institutional collaboration is ongoing to determine if a prospective trial is warranted to define the role of regorafenib as a possible chemotherapy re-sensitizing agent.