Overall survival of immunotherapy versus standard of care in chemorefractory microsatellite stable metastatic colorectal cancer: a propensity score matched analysis of 708 patients.
Immune checkpoint inhibitors (ICIs) have limited efficacy in proficient mismatch repair/microsatellite stable (pMMR/MSS) metastatic colorectal cancer (mCRC). However, selected patients with specific metastatic patterns may derive benefit.
Patients with chemorefractory pMMR/MSS mCRC treated with ICI-based regimens were retrospectively identified. A comparison cohort treated with trifluridine/tipiracil±bevacizumab, regorafenib, or fruquintinib as standard of care (SOC) was generated through 1:1 propensity score matching by age, sex, Eastern Cooperative Oncology Group performance status (ECOG PS), liver metastases (present/absent), and RAS/BRAF status. Overall survival (OS) was compared using Cox regression.
A total of 354 patients treated with ICIs and 354 treated with SOC were matched. Median age was 55 years, 52% male, 32% ECOG PS 0, 30% right-sided, and 69% RAS mutated in both groups, while 61% and 60% had liver metastases, respectively. Median OS (mOS) was 10.8 months with ICIs and 9.0 months with SOC (HR 0.76, 95% CI 0.64 to 0.92, p=0.004). In patients without liver metastases, mOS was longer with ICIs than SOC (19.1 vs 13.2 months, HR 0.59, 95% CI 0.43 to 0.80, p<0.001), whereas outcomes were similar in patients with liver metastases (6.4 vs 6.5 months, p=0.303). In univariable analyses, age, sex, primary tumor site, and RAS/BRAF status were not associated with OS. Treatment with ICIs, absence of liver metastases, one prior line of therapy, less than three metastatic sites, and ECOG PS 0 were associated with the most favorable outcomes in univariable and multivariable models.
In chemorefractory pMMR/MSS mCRC without liver metastases, ICI-based regimens yielded longer OS than SOC. Further investigation of ICIs in this patient population is warranted.
Patients with chemorefractory pMMR/MSS mCRC treated with ICI-based regimens were retrospectively identified. A comparison cohort treated with trifluridine/tipiracil±bevacizumab, regorafenib, or fruquintinib as standard of care (SOC) was generated through 1:1 propensity score matching by age, sex, Eastern Cooperative Oncology Group performance status (ECOG PS), liver metastases (present/absent), and RAS/BRAF status. Overall survival (OS) was compared using Cox regression.
A total of 354 patients treated with ICIs and 354 treated with SOC were matched. Median age was 55 years, 52% male, 32% ECOG PS 0, 30% right-sided, and 69% RAS mutated in both groups, while 61% and 60% had liver metastases, respectively. Median OS (mOS) was 10.8 months with ICIs and 9.0 months with SOC (HR 0.76, 95% CI 0.64 to 0.92, p=0.004). In patients without liver metastases, mOS was longer with ICIs than SOC (19.1 vs 13.2 months, HR 0.59, 95% CI 0.43 to 0.80, p<0.001), whereas outcomes were similar in patients with liver metastases (6.4 vs 6.5 months, p=0.303). In univariable analyses, age, sex, primary tumor site, and RAS/BRAF status were not associated with OS. Treatment with ICIs, absence of liver metastases, one prior line of therapy, less than three metastatic sites, and ECOG PS 0 were associated with the most favorable outcomes in univariable and multivariable models.
In chemorefractory pMMR/MSS mCRC without liver metastases, ICI-based regimens yielded longer OS than SOC. Further investigation of ICIs in this patient population is warranted.
Authors
Vetere Vetere, Osterlund Osterlund, Yousef Yousef, Payapwattanawong Payapwattanawong, Maddalena Maddalena, Alshenaifi Alshenaifi, Alfaro Alfaro, Knafl Knafl, Morris Morris, Parseghian Parseghian, Raghav Raghav, Wolff Wolff, Dasari Dasari, Overman Overman, Kopetz Kopetz, Shen Shen
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