S1 Ep114: Applying Updated Breast Cancer Findings From ASCO to Clinical Practice

Oncology On The Go

Following the 2024 American Society of Clinical Oncology (ASCO) Annual Meeting, Neil M. Iyengar, MD, and Paolo Tarantino, MD, co-hosted a live X Space with CancerNetwork® and discussed the latest trial updates that may impact clinical practice in the breast cancer field.

Iyengar is an associate attending physician at Memorial Sloan Kettering Cancer Center and a co-editor-in-chief of ONCOLOGY®. Tarantino is a clinical research fellow at Dana-Farber Cancer Institute and Harvard Medical School.

Iyengar and Tarantino discussed data regarding several trials and studies presented at the meeting. These presentations included:

· Phase 3 DESTINY-Breast06 Trial (NCT04494425)1

o Investigators evaluated treatment with trastuzumab deruxtecan (T-DXd; Enhertu) compared with investigator’s choice of chemotherapy among patients with hormone receptor (HR)–positive, HER2-low or HER2-ultralow metastatic breast cancer.
o The median progression-free survival (PFS) was 13.2 months with T-DXd compared with 8.1 months in patients who received chemotherapy across the HER2-low population (HR, 0.62; 95% CI, 0.51-0.74; P <.0001).
o Primary analysis overall survival (OS) data show favorable trends in the T-DXd arm across the HER2-low group (HR, 0.83; 95% CI, 0.66-1.05; P = .1181) and the intent-to-treat (ITT) population (HR, 0.81; 95% CI, 0.65-1.00). However, the OS data only reached 40% maturity at the time of the analysis.
· Phase 3 postMONARCH Study (NCT05169567)2
o Patients with HR-positive, HER2-negative breast cancer and disease progression on CDK4/6 inhibitors and endocrine therapy were assigned to receive abemaciclib (Verzenio) or matched placebo plus fulvestrant (Faslodex).
o The median PFS per investigator assessment was 5.6 months (95% CI, 5.4-9.2) with abemaciclib-based therapy vs 3.9 months (95% CI, 3.7-5.4) with placebo plus fulvestrant (HR, 0.66; 95% CI, 0.48-0.91; P = .01).
o The investigator-assessed objective response rate (ORR) was 17% vs 7% in each respective arm.
· Phase 2 SACI-IO HR+ Trial (NCT04448886)3

o Investigators assessed sacituzumab govitecan-hziy (Trodelvy) alone or in combination with pembrolizumab (Keytruda) for HR-positive, HER2-negative metastatic breast cancer regardless of PD-L1 status.
o Combination therapy yielded a numerical improvement in median PFS (8.12 months; 95% CI, 4.51-11.12) compared with sacituzumab govitecan monotherapy (6.22 months; 95% CI, 3.85-8.68), although this improvement did not reach statistical significance (HR, 0.81; 95% CI, 0.51-1.28; P = .37).
o Immature OS data presented at the meeting highlighted a median OS of 18.52 months (95% CI, 16.55-not applicable [NA]) vs 17.96 months (95% CI, 12.50-NA) in each respective arm (HR, 0.65; 95% CI, 0.33-1.28; P = .21).

References

1. Curigliano G, Hu X, Dent RA, et al. Trastuzumab deruxtecan (T-DXd) vs physician’s choice of chemotherapy (TPC) in patients (pts) with hormone receptor-positive (HR+), human epidermal growth factor receptor 2 (HER2)-low or HER2-ultralow metastatic breast cancer (mBC) with prior endocrine therapy (ET): primary results from DESTINY-Breast06 (DB-06). J Clin Oncol. 2024;42(suppl 17):LBA1000. doi:10.1200/JCO.2024.42.17_suppl.LBA1000
2. Kalinsky K, Bianchini G, Hamilton EP, et al. Abemaciclib plus fulvestrant vs fulvestrant alone for HR+, HER2- advanced breast cancer following progression on a prior CDK4/6 inhibitor plus endocrine therapy: primary outcome of the phase 3 postMONARCH trial. J Clin Oncol. 2024;42(suppl 17):LBA1001. doi:10.1200/JCO.2024.42.17_suppl.LBA1001
3. Garrido-Castro A, Kim, SE, Desrosiers J, et al. SACI-IO HR+: a randomized phase II trial of sacituzumab govitecan with or without pembrolizumab in patients with metastatic hormone receptor-positive/HER2-negative breast cancer. J Clin Oncol. 2024;42(suppl 17):LBA1004. doi:10.1200/JCO.2024.42.17_suppl.LBA1004