Addition of immune checkpoint inhibitors to chemotherapy versus chemotherapy alone in patients with triple-negative breast cancer: A systematic review and meta-analysis.

Background: Triple-negative breast cancer (TNBC) is a relatively common malignant tumor with high mortality rates. There are limited treatment options and current therapy regimens often fall short of providing positive outcomes. The development of immune checkpoint inhibitors (ICIs) have provided a vital treatment option although efficacy has varied. Here, we review patient response to current TNBC treatment with and without the addition of ICIs.

Methods: A systematic search of PubMed, Cochrane, and EMBASE library databases was done to search eligible studies published from their inception through April 3, 2022. The primary outcome indicators used were progression-free survival (PFS), overall survival (OS), pathological complete response rate (pCR) and objective remission rate (ORR), while adverse events (AEs) were also analyzed. Publication bias and sensitivity analyses and were performed to evaluate the quality of assessment.

Results: Overall, the meta-analysis looked at seven randomized controlled trials (RCTs) that included 4631 patients with TNBC. Results showed an improvement in PFS for patients receiving ICI in addition to chemotherapy (CT) in both the intent-to-treat (ITT) population and PD-L1 positive patients. Increased pCR rates were observed in all patients irrespective of PD-L1 status as well as increased ORR in the ITT which was more notable in PD-L1 positive subjects. While significant improvement in OS was observed only in PD-L1 positive individuals, the use of ICIs plus CT resulted in severe adverse reactions, specifically immune-related.

Conclusions: This study supports the increased efficacy of ICIs in combination with CT compared to CT alone in patients with TNBC, with the most notable benefit observed in PD-L1 positive patients. However, combination therapy increases the risk of adverse reactions which warrants further investigation.