At the 2022 ASCO Annual Meeting, Christine Parseghian, MD, reviewed results from a phase 2 trial assessing efficacy of panitumumab plus or minus trametinib in patients with RAS/BRAF wild-type colorectal cancer and compared EGFR rechallenge strategies with available agents in the third-line setting.
At the 2022 American Society of Clinical Oncology (ASCO) Annual Meeting, Christine M. Parseghian, MD, assistant professor in the Department of Gastrointestinal Medical Oncology at The University of Texas MD Anderson Cancer Center in Houston, spoke with CancerNetwork® about a phase 2 study she presented about rechallenging with anti-EGFR therapy of panitumumab (Vectibix) plus or minus the MEK inhibitor trametinib (Mekinist) in patients with RAS/BRAF wild-type colorectal cancer (CRC).
The results showed that patients without acquired resistance mutations who were treated with panitumumab alone (n = 33) achieved an objective response rate of 18% (95% CI, 7%-35%) and a disease control rate of 64% (95% CI, 45%-80%). Comparing these results with those from studies supporting FDA approvals of agents used in the third-line setting, Parseghian says clinicians should be looking toward rechallenge strategies more often.
As of right now in colon cancer, [for approved therapies in the third line such as] TAS-102 [Lonsurf] and regorafenib [Stivarga], we know that response rates are not ideal. They’re about 2% to 4% with those regimens with an overall response rate of about 20%. [However], in a number of these rechallenge studies, we are seeing a response rate averaging anywhere from 20% to 30%, which is already better than the 2% to 4% [rate we see] in those third-line, FDA-approved regimens, with disease control rates upwards of 70% or 80%. We are doing better. I would encourage our colleagues to rechallenge folks with anti-EGFR therapy and look for clinical trials. There are several across the country and the world. [Investigators in] Italy do a lot of these rechallenge studies as well. We are trying to identify how to best rechallenge patients with these mutations and combine [therapies] with alternative agents to overcome that resistance. There is a special cohort of patients who may benefit, and this needs to be taken advantage of rather than [attempting treatment with TAS-102] or regorafenib that a lot of the community is unfortunately [using]. We need to spread the word on rechallenge efficacy.
Parseghian CM, Sanchez EV, Sun R, et al. Phase 2 study of anti-EGFR rechallenge therapy with panitumumab with or without trametinib in advanced colorectal cancer. J Clin Oncol. 2022;40(16) 3520. doi: 10.1200/JCO.2022.40.16_suppl.3520