Late-Breaking Abstracts

In this video, Dr Elisa Agostinetto discusses and comments on the data of some interesting studies presented at the late-breaking oral session at SABCS 2024. 

The MARGOT trial investigated a neoadjuvant treatment for HER2-positive early breast cancer, focusing on patients with specific CD16A genotypes. The study compared two regimens: paclitaxel with margetuximab and pertuzumab (experimental arm) versus paclitaxel with trastuzumab and pertuzumab (control arm). This trial used anthracycline-free regimens, with the primary endpoint being pathological complete response (PCR). Unfortunately, there was no significant difference in PCR rates between the arms, and survival data remain immature. Safety profiles were similar, though the margetuximab arm showed higher infusion-related reactions. Exploratory biomarker analyses are ongoing to understand differences between responders and non-responders.

The PADMA trial, presented by Dr. Sibylle Loibl, evaluated treatments for high-risk, hormone receptor-positive, HER2-negative metastatic breast cancer. It compared palbociclib plus endocrine therapy with monotherapy chemotherapy. Results showed improved progression-free survival and time to treatment failure in the palbociclib group, along with a numerical (though not statistically significant) survival benefit. These findings reinforce the position of CDK 4/6 inhibitors with endocrine therapy as the standard first-line treatment for this patient population.

The DESTINY-Breast 06 sub-analysis focused on trastuzumab deruxtecan’s efficacy in patients with hormone receptor-positive, HER2-low, or HER2-ultra-low metastatic breast cancer. These patients had received prior CDK 4/6 inhibitors plus endocrine therapy. The results revealed that trastuzumab deruxtecan maintained its efficacy irrespective of the pace of progression on prior therapy and across both primary and secondary endocrine resistance. This highlights the treatment’s broad applicability in these subgroups.

Finally, the KEYNOTE-522 exploratory biomarker analysis presented data on triple-negative breast cancer treated with chemotherapy plus pembrolizumab in the neoadjuvant setting. Previous results demonstrated pembrolizumab’s superiority in PCR, event-free survival, and overall survival compared to chemotherapy alone. This analysis explored potential prognostic and predictive biomarkers, such as tumour mutational burden (associated with event-free survival) and a T-cell-inflamed gene signature (correlated with PCR and event-free survival). While these findings are exploratory and do not yet alter clinical practice, they pave the way for future trials on chemoimmunotherapy.