421P - Impact of novel agents in patients with stage IV denovo HR+ve/Her2-ve breast cancer: Results from a real-world dataset

Background

The objective of this retrospective study was to look at the impact of CDK4/6i and other novel agents among pts with stage IV denovo HR+ve/HER2-ve breast cancer (BC).

Methods

We utilized a federated network of de-identified health data representing approximately 145 million pt lives available through the TriNetX Research Network. We identified pts with HR+ve/HER2-ve stage IV denovo BC treated with CDK4/6i diagnosed between Jan 2004 and Jan 2024. Propensity score matching analysis by age and site of metastases was carried out. OS was computed using the Kaplan Meier product limit method. The index event is the date of diagosis diagnosis.

Results

7025 pts with stage IV Denovo HR+ve/HER2-ve were identified of whom 940 (13.4%), 4,287 (60.4%) and 2,502 (35.6%) pts received Ribo, Palbo and Abema respectively. 57 (0.81%) received elacestrant (ELA), 2,720 (38.3%) received fulvestrant (FUL), 112 (1.6%) received PARPi and 165 (2.35%) received an antibody drug conjugate (ADC). Median OS was 6.8yrs. Median OS was similar between Ribo and Abema (HR 1.27; 95%CI (0.93, 1.73) p=0.13). Compared to pts receiving Palbo, pts who received Ribo (HR 0.76; 95%CI (0.58, 0.99) p=0.04) and Abema (HR 0.58; 95%CI (0.48,0.69) p<0.0001) had a better median OS respectively.720 pts received >1 CDK4/6i (210 received Palbo + Ribo, 125 Ribo + Abema, 440 Abema + Palbo). Median OS was 6.3y and 9.4y (HR 1.61; 95%CI (1.33,1.95) p<0.0001) respectively among pts who received 1 vs >1 CDK4/6i. OS was significantly longer among pts who received ELA vs those who did not (HR: 0.30 95% CI (0.16,0.57) p=0.0001) and among pts who received ELA + ful vs those who received FUL alone (p=0.0022). Among pts who received ELA 39.1% received CDK4/6i for >12m. Pts who received ELA 1-yr OS from the start of ELA was 77.1% and 60.6% among pts who received CDK4/6i >12m and <12m respectively (p= 0.56). OS was significantly longer among pts who received an ADC compared to those who did not (HR: 0.48 95% CI (0.33,0.72), p= 0.0002).Among pts who received PARPi 85% and 15% received it pre and post CDK4/6i respectively. Median OS among pts who received PARPi was 5.4y.

Conclusions

Among pts with stage IV denovo HR+ve/HER2-ve BC treated with a CDK4/6i novel agents such as oral SERDS and ADCs have improved prognostic outcome.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

author.

Funding

Has not received any funding.

Disclosure

S. Dawood: Financial Interests, Personal, Advisory Board: Roche, AstraZeneca, Lilly, Merck, Gilead; Financial Interests, Personal, Invited Speaker: Roche, MSD, BMS, Pfizer, Lilly, AstraZeneca, caris; Financial Interests, Institutional, Research Grant: MSD, Amgen; Non-Financial Interests, Member: ASCO, ESMO. All other authors have declared no conflicts of interest.