Complete remissions following immunotherapy or immuno-oncology combinations in cancer patients: the MOUSEION-03 meta-analysis

Background Immunotherapy has determined unprecedented long-term responses in several hematological and solid tumors. In the MOUSEION-03 study, we conducted a meta-analysis to determine the possibility of achieving complete remissions (CR) with immunotherapy or immuno-oncology combinations in cancer patients.Methods The primary endpoint was to assess the incidence of CR in cancer patients receiving immune checkpoint inhibitors (ICIs) alone or in combination with other agents versus control treatments. The pooled odds ratio (OR) and 95% confidence interval (CI) for CR rate were extracted.Results A total of 12,130 potentially relevant trials were identified; 5 phase II and 80 phase III randomized studies (37 monotherapies and 48 combinations) and 49,425 cancer patients were included. The most frequent types of malignancies were non-small cell lung cancer (n = 14,249; 29%), urothelial cancer (n = 6536; 13%), renal cell carcinoma (n = 5743; 12%), and melanoma (n = 2904; 6%). In patients treated with immunotherapy (as monotherapy or in combination with other anticancer agents), the pooled OR was 1.67 (1.52-1.84). The highest OR was registered by immune-based combinations with two ICIs (3.56, 95% CI 1.28-9.90).Conclusions To the best of the authors' knowledge, no comprehensive meta-analysis on the use of ICIs and ICI-based combinations in solid tumors to systematically investigate the probability to achieve CR has been published so far. Although CR is not a common event in several cancer patients receiving immunotherapy, the MOUSEION-03 suggests that the use of ICIs may significantly increase the chance of achieving CR in comparison with control treatments.