Efficacy and safety of neoadjuvant combination immunotherapy in surgically resectable malignant solid tumors: a systematic review and meta-analysis.

Objectives: Neoadjuvant immunotherapy has emerged as a prominent research focus recently. For potentially operable patients, neoadjuvant therapy serves as a primary method to reduce tumor load and facilitate surgical interventions.

Methods: We retrieved articles from PubMed, Embase, Cochrane Library, American Society of Clinical Oncology, and European Society of Medical Oncology websites from inception to December 2023. Statistical analyses were performed using the R software. Primary outcomes assessed included major pathological response (MPR), pathological complete response (pCR), and treatment-related adverse events (trAEs).

Results: 29 studies encompassing 1163 patients were included. The MPR rate of neoadjuvant combination immunotherapy was 38% (95% confidence interval [CI]: 25%-52%), and the pCR rate was 33% (95%CI: 25%-42%). These values were significantly higher than those obtained with single agent immunotherapy (p < 0.001). The pooled incidence of overall trAEs was 83% (95%CI: 73%-92%), and grade (G) 3-4 trAEs was 22% (95%CI: 15%-29%), both significantly higher than those observed with single agent immunotherapy (p < 0.05).

Conclusion: This study demonstrated the efficacy of neoadjuvant combination immunotherapy. Given that the majority of the included trials were phase II with small sample sizes, further multicenter phase III randomized controlled trials should be conducted to validate the findings of the review.