Efficacy of CDK4/6i in the visceral crisis setting: Result from a real-world database.

Abstract

1047 Background: The combination of the CDK4/6 inhibitors(CDK4/6i) and endocrine therapy has improved overall survival(OS) in patients(pts) with either endocrine sensitive or resistant disease who are not in visceral crisis. The goal of this retrospective analysis of a real world database was to look at the efficacy of CDK4/6i among pts with hormone receptor positive (HR+ve)/HER2-ve metastatic breast cancer(MBC) who present with visceral crisis at diagnosis. Methods: For this analysis, we utilized a federated network of de-identified health data representing approximately 64 million patient lives available through the TriNetX Platform. We identified 5966 pts who had HR+ve/HER2-ve MBC diagnosed between 2015 and 2020. OS was computed using the Kaplan Meier product limit method. Propensity score matching was performed on all comparisons of survival. Visceral crisis was defined as either liver metastases with liver dysfunction, lymphangitis with dyspnea or the presence of pancytopenia. Results: 906(15%) pts received CDK4/6i. OS any time after treatment among pts who did and did not receive CDK4/6i was significantly different (p=0.0002) favoring the group receiving CDK4/6i, with median OS at 59.6 months and 46.2 months and 2-year OS at 71.6% and 61.4% respectively. Among pts who received CDK4/6i versus another treatment as first line therapy, OS was significantly different(HR 0.7, 95%CI 0.57 – 0.86, p<0.0001), and median OS was 59.6 months and 41.5 months respectively. 336 pts with HR+ve mbc presented with visceral crisis at the time of diagnosis of whom 61(18%) received CDK4/6i therapy as first line therapy. Median OS among pts who did and did not have visceral crisis at diagnosis and received treatment was 8.1 months and 210 months respectively. OS any time after initial treatment was significantly different among pts with visceral crisis who did and did not receive CDK4/6i (p=0.01), with 2-year OS at 26.1% and 8.1% and median OS at 11 months and 6 months respectively Conclusions: The use of CDK4/6i in the presence of visceral crisis at diagnosis was associated with a 5 month improvement in OS compared to chemotherapy. Future clinical trials should explore the use of CDK4/6i in the setting of visceral crisis.