Abstract 230P
Background
No reliable biomarkers exist to predict response to CDK4/6 inhibitors (CDK4/6i) in patients (pts) with metastatic breast cancer (MBC). FDG-PET scan, thanks to its sensitivity in detecting early metabolic changes in the tumour, could identify pts who will benefit from CDK4/6i.
Methods
PUCCINI (PET evalUation in advanced breast Cancer treated with Cdk 4/6 INhIbitors) is a retrospective study conducted at Institut Jules Bordet evaluating the association between metabolic response by FDG-PET scan (assessed by PERCIST and CONSIST criteria) and survival (progression-free survival [PFS], overall survival [OS]) in pts with hormone receptor-positive, HER2-negative MBC receiving CDK4/6i and endocrine therapy (ET). FDG-PET scans were performed at baseline (i.e., before starting therapy) and at the first disease re-evaluation (i.e., 90 ± 15 days after starting therapy). Responders were defined as pts achieving a complete or partial (by PERCIST) or class I (by CONSIST) metabolic response. In this preliminary analysis, survival was estimated with the Kaplan-Meier method and compared by the log rank test and Cox proportional hazard models.
Results
This preliminary analysis was conducted on 28 eligible pts. After a median follow-up of 38.5 months (95% CI 35.9-41.1), we observed 18 disease progressions and 7 deaths. FDG-PET scans were evaluable by CONSIST and PERCIST in 24 patients. Metabolic response both by PERCIST and by CONSIST were significantly associated with longer PFS (Table). OS data are still immature (not presented). Table: 230P
| CONSIST (n=24) | PERCIST (n=24) | |||||
| PFS events / Total N | mPFS (months) | HR (95% CI) | PFS events / Total N | mPFS (months) | HR (95% CI) | |
| Responders | 8/18 | NR | 0.20 (0.06-0.64) | 10/20 | 33.3 | 0.16 (0.05-0.55) |
| Non-responders | 6/6 | 7.0 | 4/4 | 5.7 |
HR: hazard ratio, NR: not reached.
Conclusions
Early metabolic response by FDG-PET scan in pts with MBC receiving CDK4/6i and ET is associated with longer PFS. Assessment of early metabolic response by FDG-PET scan is a promising strategy to identify pts who will benefit from CDK4/6i. More mature data on a larger cohort from the PUCCINI study will provide stronger evidence.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
E. Agostinetto: Financial Interests, Personal, Invited Speaker, Speaking fee + Support to attend medical conference: Lilly; Financial Interests, Personal, Writing Engagements: Sandoz; Financial Interests, Personal, Other, Support to attend medical conference: Roche, Novartis, Genetic, Istituto Gentili. M. Brandão: Financial Interests, Personal, Other, travel grants: Sanofi; Financial Interests, Personal and Institutional, Other, Speaker honoraria + travel grant + Research grant to my Institution: Roche/GNE; Financial Interests, Personal, Invited Speaker: Janssen; Financial Interests, Institutional, Research Grant: AstraZeneca, Pfizer, iTEOS, Merck. M. Piccart: Financial Interests, Personal, Invited Speaker: Astra-Zeneca, Lilly, MSD, Novartis, Pfizer; Financial Interests, Personal, Other, Consultant: Camel-IDS/Precirix; Financial Interests, Personal, Advisory Board: Immunomedics, Menarini, Odonate, Seattle Genetics, Immutep, SeaGen, Gilead, NBE Therapeutics, Frame Therapeutics; Financial Interests, Personal, Advisory Board, Consultant and invited speaker: Roche-Genentech; Financial Interests, Personal, Invited Speaker, Scientific Board: Oncolytics; Financial Interests, Institutional, Research Grant: Astra-Zeneca, Immunomedics, Lilly; Financial Interests, Institutional, Funding: Menarini, MSD, Novartis, Pfizer, Radius, Roche-Genentech, Servier, Synthon. E. de Azambuja: Financial Interests, Personal, Advisory Board: Roche/GNE, Novartis; Financial Interests, Personal, Invited Speaker: Seattle Genetic, Zodiac, Libbs, Pierre Fabre; Financial Interests, Institutional, Research Grant: Roche/GNE, AstraZeneca, GSK/Novartis, Servier; Financial Interests, Institutional, Other, Travel Grant: Roche/GNE. All other authors have declared no conflicts of interest.