CDK4/6 inhibitors (CDK4/6i) combined with endocrine therapy (ET) are the established first-line (1L) therapy for patients (pts) with hormone receptor (HR)-positive/HER2-negative (HR+/HER2-) metastatic breast cancer (mBC). Data supporting the best treatment choice at progression on CDK4/6i+ET is limited.
We collected data from pts with HR+/HER2- mBC who received treatment after progression to CDK4/6i+ET in five Italian Institutions. Progression-free survival 2 (PFS2), the primary endpoint, was calculated from initiation of CDK4/6i to disease progression (PD) on subsequent line of therapy or patient death. The PFS2-PFS1 difference and PFS2/PFS1 ratio were also estimated. We compared outcomes between pts receiving chemotherapy (CT)- or ET-based regimens immediately after CDK4/6i+ET.
As of January 2023, 511 pts were included. Median patient age was 59 years, 26.2% had
After progression to CDK4/6i, ET-based regimens are associated with longer PFS2 and OS when compared to CT. However, this likely reflects clinical benefit from previous CDK4/6i+ET. For pts with short PFS on CDK4/6i+ET, CT may be a more effective option.
The authors.
Has not received any funding.
R. Caputo: Financial Interests, Personal, Other, Advisory or speaker bureau: Novartis, Lilly, Roche, AstraZeneca, MSD, Gilead, Daiichi Sankyo, Veracyte, Seagen, Pfizer, Eisai. C. Vernieri: Financial Interests, Personal, Invited Speaker: Novartis, Eli Lilly, Istituto Gentili; Financial Interests, Personal, Advisory Board: Novartis, Daiichi Sankyo; Financial Interests, Personal, Advisory Role: Pfizer; Financial Interests, Personal, Research Grant: Roche. E. Munzone: Financial Interests, Personal, Advisory Board: Eisai, Exact Science, MSD Oncology, Daiichi Sankyo/AstraZeneca, Pfizer, Seagen. M. Lambertini: Financial Interests, Personal, Advisory Board: Roche, AstraZeneca, Lilly, Novartis, Pfizer, Exact Sciences, MSD, Seagen, Gilead; Financial Interests, Personal, Invited Speaker: Takeda, Sandoz, Ipsen, Libbs, Knight, Daiichi Sankyo, Lilly, Pfizer, Novartis, Roche; Financial Interests, Personal, Other, Travel grant to attend ASCO 2022: Gilead; Financial Interests, Institutional, Invited Speaker, 2-year research grant paid to my Institution: Gilead. M. De Laurentiis: Financial Interests, Personal, Invited Speaker, or honoraria: AstraZeneca, Amgen, Celgene, Daiichi Sankyo, Eisai, Eli Lilly, Exact Science, Gilead, MSD, Novartis, Pfizer, Pierre Fabre, Roche, Seagen, Takeda, Ipsen; Financial Interests, Personal and Institutional, Funding: Novartis, Roche, Lilly, Puma Biotechnology, Pfizer, Daiichi Sankyo, MSD, MacroGenics, BMS. G. Viale: Financial Interests, Personal, Advisory Board: Gilead; Financial Interests, Personal, Speaker’s Bureau: Novartis, Lilly; Financial Interests, Personal, Other, Travel expenses: Pfizer, Lilly. G. Curigliano: Financial Interests, Personal, Invited Speaker: Roche, AstraZeneca, Daiichi Sankyo, Novartis, Pfizer; Financial Interests, Personal, Advisory Board: Roche, AstraZeneca, Daiichi Sankyo, Lilly, Pfizer, Veracyte, BMS, Merck, Exact Sciences, Celcuity; Financial Interests, Personal, Other, Advisory Board: Ellipsis; Financial Interests, Institutional, Research Grant, Investigator Initiated Trial: Merck; Financial Interests, Institutional, Funding, Phase I studies: BMS, Novartis, AstraZeneca, Daiichi Sankyo, Roche, Blueprint Medicine, Kymab, Astellas, Sanofi, Philogen; Financial Interests, Institutional, Invited Speaker, Phase I clinical basket trial: Relay Therapeutics; Non-Financial Interests, Officer, Italian National Health Council as Advisor for Ministry of Health: Consiglio Superiore di Sanità; Non-Financial Interests, Advisory Role, Member of the Scientific Council. Patient advocacy association: Europa Donna; Non-Financial Interests, Advisory Role, Cancer Research Foundation: Fondazione Beretta; Non-Financial Interests, Invited Speaker, No compensation for this role. This a public national company for cancer prevention: Lega Italiana Lotta ai Tumori; Non-Financial Interests, Officer, Member of the Advisory Council: EUSOMA; Non-Financial Interests, Officer, ESMO Clinical Practice Guidelines Chair: ESMO. C. Criscitiello: Financial Interests, Personal, Invited Speaker: Pfizer, Novartis, Eli Lilly, Roche, Gilead; Financial Interests, Personal, Advisory Board: MSD, Seagen, AstraZeneca, Daiichi Sankyo. All other authors have declared no conflicts of interest.