4CPS-033 Real-world treatment patterns and outcomes of selective cyclin-dependent kinase (CDK) 4/6 inhibitors utilisation in metastatic breast cancer – REVEAL study

Background and Importance Active involvement of hospital pharmacists in real-world effectiveness studies is paramount to generate evidence about the value of innovative medicines in clinical practice. The REVEAL study was designed and implemented by a cooperative research group of hospital pharmacists to assess the therapeutic value of current standard of care with CDKi4/6 in HER2-negative, hormone receptor-positive metastatic breast cancer (MBC:HR+;HER2(-)). Aim and Objectives To characterise treatment patterns of CDK4/6 inhibitors palbociclib and ribociclib use in women with MBC. To quantify dose adjustments until 6 months of CDKi4/6 treatment. To estimate persistence on treatment with ribociclib at 12 and 24 months. Material and Methods Retrospective observational cohort study, including adult women with MBC: HR+;HER2(-) who used CDKi4/6 (ribociclib or palbociclib) in addition to hormone therapy, between March and December 2019. Data was from records of the Hospital Pharmaceutical Services. The study comprised two follow-ups: until June 2020 to quantify dose adjustments; until 24 months to assess persistence on treatment with ribociclib (last observation 31 December 2021). Study protocol was approved by hospitals' Ethics Committees. Persistence on treatment with ribociclib was calculated using the Kaplan-Meier estimator. A significance level of 5% was adopted. Results We included 121 women from seven public hospitals: palbociclib (n=86;71.1%); ribociclib (n=35; 28.9%). The average age (min; max) was 58 (27; 92) years. Most patients started CDKi4/6 treatment in postmenopause (n=85; 70.2%) and as second-line therapy (n=87; 71.9%). Combination with hormonal therapy was aromatase inhibitors 97% in ribociclib and 71% in palbociclib patients (p-value=0.003); fulvestrant in 6.1% ribociclib and 33.9% palbociclib patients (p-value=0.003). The majority (76%) of patients had no dose adjustment in the first 6 months. There were no significant differences in the proportion of patients with dose modifications according to CDK4/6 inhibitor, patient's age, type of hormonotherapy or therapy line. The median persistence on treatment with ribociclib was 16.3 months (95% CI= 10;NA). Persistence 95% CI on treatment with ribociclib at 12 months was 57% 40%;81% and at 24 months 43% 26%; 73%. Conclusion and Relevance The REVEAL study confirmed the effectiveness of CDKi4/6 in real-world settings, including dose adjustments and persistence on treatment. Leadership in real-world effectiveness studies is paramount to elevate the role of pharmacists in establishing the therapeutic value of innovative medicines. References and/or Acknowledgements Conflict of Interest Conflict of interest. Corporate sponsored research or other substantive relationships: This project was developed within the framework of a clinical research collaboration protocol established between Novartis Farma, Produtos Farmacêuticos S.A., Exigo Consultores and a group of Portuguese hospitals.