Panacea for all things malignant.

We’re talking PD-1 axis inhibition, of course. Early reporting of the phase 1b/2 PANACEA trial suggested beneficial effects with the addition of pembrolizumab for select women with trastuzumab-refractory HER2(+) breast cancer. The full reporting is out this week, and sadly it’s no game-changer. While the phase 1 component was dose-finding (n=12), in the end Merck decided to go with its standard 200 mg q3 weeks. Among all 58 women enrolled, the primary endpoint of objective response was seen in only 7. But all responders had at least some expression of PD-L1 in tumor or stroma meaning an objective response rate of 15% was seen among PD-L1(+) patients (n=46), and another 4 PD-L1(+) patients achieved stable disease for at least 6 months. TBL: Early data suggests roughly one-quarter of women with HER2(+), PD-L1(+) breast cancer refractory to trastuzumab can achieve chemo-free disease control with the addition of pembro. | Loi, Lancet Oncol 2019