A systematic review and meta-analysis of randomized controlled trials to evaluate the risk of gastrointestinal and hepatic toxicities in patients with hormone receptor-positive HER2-negative metastatic breast cancer treated with CDK 4/6 inhibitors.

Abstract

209 Background: Hormonal therapies function through CDK4/CDK6/E2F axis which is essential in luminal estrogen receptor positive breast cancer. Reactivation of these CDK4 and CDK6 kinases has been implicated in endocrine resistance. Many CDK 4/6 inhibitors were employed in studies with noteworthy safety concerns. We performed a systematic review and meta-analysis of randomized controlled trials (RCTs) to determine the risk of gastrointestinal (GI) and hepatic toxicities. Methods: MEDLINE, EMBASE databases and meeting abstracts from inception through June 2017 were queried. RCTs that mention GI symptoms and elevation of liver enzymes as adverse effects were incorporated in the analysis. Mantel-Haenszel method was used to calculate the estimated pooled risk ratio with 95% confidence interval (CI). Results: We included five RCTs with a total of 2671 patients treated with CDK 4/6 inhibitors. The study arm used palbociclib-letrozole, palbociclib-fulvestrant, ribociclib-letrozole and abemaciclib-fulvestrant while the control arm used placebo in combination with letrozole or fulvestrant. The relative risks (RR) of all-grade side effects were as follows: diarrhea, 1.72 (95% CI: 1.08 – 2.74, p = 0.02); stomatitis, 2.62 (95% CI: 1.43 – 4.79, p = 0.002); nausea, 1.59 (95% CI: 1.30–1.94; p < 0.0001); vomiting, 1.65 (95% CI: 1.06–2.56; p = 0.02); elevated AST, 2.30 (95% CI: 1.34–3.93; p = 0.002); and elevated ALT, 2.78 (95% CI: 1.90–4.08; p < 0.0001). The RR of high-grade side effects were as follows: diarrhea, 2.26 (95% CI: 0.39 – 13.09, p = 0.36); stomatitis, 2.14 (95% CI: 0.36 – 12.72, p = 0.40); nausea, 1.13 (95% CI: 0.28 –4.47; p = 0.86); vomiting, 0.79 (95% CI: 0.24 – 2.54; p = 0.69); elevated AST, 1.85 (95% CI: 0.74 – 4.64; p = 0.18); and elevated ALT, 4.33 (95% CI: 2.15 – 8.71; p < 0.0001). Conclusions: The risk of developing any-grade diarrhea, stomatitis, nausea, vomiting and elevated AST and ALT, was high in CDK 4/6 inhibitors based regimen. Moreover, it increased the risk of high-grade elevated ALT.