With the HER2DX assay — a genomic tool for patients with early-stage HER2-positive breast cancer — gaining attention as a potential predictor of pathologic complete response (pCR), experts are exploring how it might personalize neoadjuvant therapy in these patients.
In this fifth segment of MedPage Today‘s expert roundtable, William Gradishar, MD, of Northwestern University Feinberg School of Medicine in Chicago, joins moderator Hope Rugo, MD, of the City of Hope Comprehensive Cancer Center in Duarte, California, and Laura Huppert, MD, of the University of California San Francisco, to discuss early findings from the CompassHER2-pCR trial and the evolving value of predictors like HER2DX.
Watch the entire roundtable series here.
Following is a transcript of their remarks:
Rugo: I mean, I think DB11 [DESTINY-Breast11] is interesting. I mean, we’ll have to see the breakdown in ER [estrogen receptor]-positive/ER-negative because we saw data from Compass pCR, the ECOG [Eastern Cooperative Oncology Group] trial, looking at THP [taxane, trastuzumab (Herceptin), and pertuzumab (Perjeta)] regimens for 12 weeks — with again choice of taxane — and then pCR as an endpoint. And then of course that’s attached to Compass RD, which is looking at T-DM1 [trastuzumab emtansine, Kadcyla] with or without tucatinib [Tukysa].
But Compass pCR was interesting because in the abstract they reported that the pCR rate in ER-positive disease was just about a third of the patients, whereas two-thirds with ER-negative disease had a pCR. And a third, I don’t know, a third of your patients having a pCR with THP, it seemed like, indeed, maybe we would need to take a more escalated approach. But they looked at a predictor, HER2DX, to kind of see whether or not that might help decide whether you should give more or less. Do you think that we’ll be going that route in the future? We’ll be using predictors to try and individualize?
Gradishar: Well, that’s our hope. I think the data that you’re referring to that we’ll hear more about probably doesn’t answer that question. At least in my view, it doesn’t at this point.
But I think your point about ER-[positive] versus ER-negative and what the probability of getting a [pathologic] CR if you’re HER2-positive as well, that observation has been made over a long period of time, that if you’re ER-positive, the probability of achieving a pCR is going to be less. So that on the surface, we’ve known that for a long time. But can we, in a more granular fashion, understand that using a biomarker and the HER2DX assay maybe will be useful? Although this dataset doesn’t convince me, because the numbers that are presented start getting pretty small in some of these subsets.
