DR RUGO: So in triple-negative breast cancer, there are 2 trials. Both were Phase IB expansion trials. Both included 25 to 27 patients. And they gave single-agent either pembrolizumab or atezolizumab. Both showed very similar response rates, 18.5% and 19%. And some of these responses were very durable — I mean, really impressively so.

We didn’t see a lot of the pseudoprogression. In the pembrolizumab trial, it was suggested that the time to response, the median time to response, was very, very long. But that hasn’t been seen in subsequent studies, so we don’t know if that was just the vagaries of a small Phase IB expansion trial.

There also was data presented by Sylvia Adams, quite nice data at ASCO in the poster discussion session, looking at the combination of nab paclitaxel and atezolizumab in patients who had heavily pretreated metastatic breast cancer. And they also have seen some very durable responses and saw a high initial response rate. Because it’s a single-arm trial, what we know, what we can take home from this, is that it’s a safe combination, as far as we can tell, and that the responses seem quite reasonable. And the rest of the data is going to come from the Phase III IMpassion trial that’s ongoing.

DR LOVE: What is that looking at?

DR RUGO: That’s a first-line trial with nab paclitaxel and either a placebo or atezolizumab and only in patients who have triple-negative disease without immediate prior exposure to a taxane and no prior treatment in the metastatic setting. That’s an international collaboration.

DR LOVE: And just to clarify, the rationale in choosing nab paclitaxel is because it does not need corticosteroid support?

DR RUGO: Right. It doesn’t need steroids. And so the idea was that — maybe there isn’t enough data to say that nab is better in triple-negative disease. There’s studies that are positive and studies that are negative. But we’re using just the 100 mg/m² dose, which is very tolerable. So it’s quite a reasonable choice, and with the idea that you don’t need steroids.

In our I-SPY neoadjuvant trial where pembrolizumab is one of the arms, we’ve actually successfully tapered everybody off of the premed of steroids with paclitaxel. Since we couldn’t use nab paclitaxel, there’s no indication there in the neoadjuvant setting. So I think you can do a number of different things there. Also, tapering off the steroids seems to be safe to do.

DR LOVE: And just to clarify, atezolizumab, which now is approved in bladder cancer, is anti-PD-L1 as opposed to anti-PD-1. What’s your vision about what’s the difference between them? And do you think it makes a difference, clinically?

DR RUGO: We just don’t know yet. We just don’t have enough information. And we certainly don’t have enough information in breast cancer. I think these agents won’t all be identical. They are antibodies, so they’re all, in essence, biosimilars, and they are different. So these are different drugs. We’re going to have to see. I think that understanding in breast cancer whether you need PD-L1 positivity for a response is important and, of course, the subsets.

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