DR RUGO: We’ve recently seen some late toxicities from pembrolizumab. I think they’ll exist with all of these agents. And in the data with pembrolizumab published by Rita Nanda, there were 2 patients who had late colitis. And I mean 90 and 120 days late, after the last dose. And we may not have seen this much in some of the other cancers, because once they went on checkpoint inhibitors, there wasn’t a lot of other therapy. They didn’t survive a long time. They didn’t have other chemotherapy agents to get.

But in this patient of mine who recently got pembrolizumab and then for ER-positive disease on a clinical trial and more than 90 days afterwards has developed persistent pan-colitis with bleeding and just was readmitted now. Now she’s four and a half months out with persistent colitis despite infliximab and steroids. This can really be an issue. We’ve also seen some more controllable late hepatitis, hypothyroidism and milder colitis. So it is something to keep in mind when you’re getting compassionate-use drug.

DR LOVE: There are a lot of agents being looked at and coming into practice in combination with other things, including chemotherapy. And that’s kind of tough to sort out sometimes. But when you have a single agent, a single novel agent, it’s a little bit more straightforward. I’m curious about how many people, total, you’ve treated on and off study with a checkpoint inhibitor with breast cancer and whether you’ve seen any patients that you could look at and say, “That person really had a clinical benefit.”

DR RUGO: So we participated quite actively, of course, in the basket trial. And I treated patients with ER-positive disease. I didn’t have the responders at my institution. And then we recently participated in a Phase II trial, which was pembrolizumab alone in patients after first line who had either PD-L1-positive or -negative disease. But we don’t know the results of the PD-L1 testing. So it’s kind of a mixed bag.

In that trial, we saw a lot of patients who had early progression. I have to say real, triple-negative aggressive disease. But I have 2 patients who had, actually, early responses. And most of them had had relatively more limited exposure to prior therapies and more limited extent of disease. I don't know if that matters as much, but there’s got to clearly be some determinant. And we won’t know until later whether those are the patients who had PD-L1 positivity or not. But I have, clearly, 2 patients who are benefiting.

And then my 2 patients on compassionate use have done very well, but they had just been on chemotherapy. So I need a little bit more time to assess their response to pembro alone.

DR LOVE: Any prolonged responses? Of course, that’s what gets everybody’s attention.

DR RUGO: Yes. Not yet, but I’m waiting — counting the days.

Genomic assays and (neo)adjuvant treatment decision-making

Early-stage breast cancer in the adjuvant and neoadjuvant settings

Management of metastatic breast cancer (mBC)

CDK4/6 inhibitors for the treatment of breast cancer

Checkpoint inhibitors and other novel immunotherapeutic approaches to breast cancer

Triple-negative and BRCA mutation-positive breast cancers