New research in the January 2023 issue of JNCCN-;Journal of the National Comprehensive Cancer Network finds that immunotherapy from immune checkpoint (PD-1) inhibitors prior to surgery was strikingly effective for patients with localized mismatch repair-deficient or microsatellite instability-high (dMMR/MSI-H) colorectal cancer (CRC).
Nearly all of the patients studied benefitted from neoadjuvant PD-1 inhibitors, with 1-of-4 experiencing complete response on clinical assessment. In addition to the short-term effectiveness, the findings showed substantial longer survival benefits from neodjuvant PD-1 inhibitors, including a low recurrence rate when compared with historic rates.
The researchers; who are based in Southern China; anticipated PD-1 inhibitors could be at least as effective for locally-advanced but operable cancer as they have historically been in the treatment of metastatic dMMR/MSI-H CRC, but were surprised to find it so much more effective for this patient population.
The study included a retrospective review of 73 patients between ages 18 and 75 with confirmed dMMR/MSI-H CRC who received any type of PD-1 inhibitor prior to surgery between October 1, 2017 and December 31, 2021. Of those 73, 48 were diagnosed with colon cancer, 18 with rectal cancer, and 7 with multiple types of CRC. 84.9% overall experienced an objective response, with 23.3% showing complete response and 61.6% partial response. The 2-year rates for tumor-specific overall survival and disease-free survival were 100% for patients who underwent surgery after PD-1 blockade.
“We need to keep in mind that our final goal is to cure patients long term, not just remove the tumor at the moment. I think care providers, especially surgeons, should refrain from scheduling immediate surgery for patients with locally advanced, or even early-stage dMMR/MSI-H colorectal cancer. With such a powerful option at hand, we have the duty to offer a safer surgery with better outcomes or a non-surgical-yet-equally-effective approach for this group of patients, especially for those who might suffer from function damage or organ sacrifice after surgery.”
Pei-Rong Ding, MD, Senior Author, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center of Cancer Medicine