Matthew Kurian, Executive Committee Member at KYSCO, shared on LinkedIn:
“Can immunotherapy finally find a role in HR+ metastatic breast cancer?
One study I’m really interested in at ESMO – European Society for Medical Oncology 2026: KEYNOTE-B49 (LBA51) presented by Hope Rugo.
Phase III testing pembrolizumab + 1L chemotherapy vs chemotherapy alone in PD-L1+ HR+/HER2− MBC after endocrine therapy.
So far, immunotherapy in HR+ MBC has been pretty underwhelming.
- KEYNOTE-028: ORR 12%
- Eribulin ± pembro: PFS 4.1 vs 4.2 months
- AMBITION: no significant PFS benefit with atezolizumab
- Recent meta-analysis of 11 RCTs = no significant PFS or ORR benefit overall.
But there have been some interesting signals in more ‘immune-hot’ HR+ tumors:
- PD-L1+
- higher TILs
- ER/PR-low
- even PAM50 non-luminal disease.
Maybe there is a subset of HR+ disease that benefits from immunotherapy?
The big question for me: Is PD-L1 enough to identify them? I don’t think so.
I think we will need to be a bit more creative with TILs and other biomarker signals to identify the needle in the haystack!”
More about this topic:
KEYNOTE-427: Long-Term Outcomes and Biomarker Analyses With 1L Pembrolizumab in Advanced RCC
