COMMENTARY

Two 'P' Words Top List of Hot Topics in Breast Cancer

Kathy D. Miller, MD

Disclosures

May 26, 2017

Hi. It's Dr Kathy Miller from Indiana University. It's going to be a really busy year at ASCO for those of us in the breast cancer sessions, so I want to give you a bit of a heads-up on what to look for. Two "P" words: PARP inhibitors and pertuzumab, which are going to be the words of the meeting for us.

First, in the plenary session, we'll see the first results of the OlympiAD trial.[1] This is a trial comparing the PARP [poly (ADP-ribose) polymerase] inhibitor olaparib versus a choice of standard chemotherapy agents in patients with BRCA1 and BRCA2 mutations. We've heard via the usual press release that this is a positive trial that met its primary endpoint. This will be our first chance to look at the details of the data.

That's exciting—not just as another potential option for our patients, but at this same meeting we're going to see results of the veliparib neoadjuvant study,[2] looking at adding carboplatin and veliparib to a standard anthracycline and taxane base. That's the follow-up phase 3 trial from the exciting data we saw from the I-SPY 2 group a couple of years ago. That trial did not meet its primary endpoint. Adding veliparib—at least, adding it to carboplatin—did not improve the outcome.

We'll not see data from the niraparib trial. We have seen in a press release that that trial's accrual was halted. We're told that the data from that trial are not likely to lead to registration. That leaves us with three PARP inhibitors with some information, one positive and two negative. We're going to need to look at the data carefully and ask: Is this a difference between the PARP inhibitors, either their potency or their spectrum of activity? Or is this a difference of trial conduct in the setting, and how will that information move us forward?

In the HER2-positive space, we're going to see the long-awaited results of the APHINITY phase 3 trial[3] looking at adding pertuzumab to adjuvant therapy in our HER2-positive patients. We know that adding pertuzumab in the first-line metastatic setting significantly improved overall survival. It improves pathologic complete response right in the neoadjuvant setting. We'll finally get a look at the adjuvant data to see whether it improves disease-free survival, how much, and at what toxicity and financial cost so that we can better guide our decisions for patients.

We're also going to look at some additional pathology data from that study in years to come to try to better understand who really needs all of that therapy and who might best be served by less therapy and less toxicity.

Finally, in the ER-positive space, [we'll hear] a lot more information about the cyclin-dependent kinase inhibitors. We know that ribociclib was recently approved, and we'll get a good look at the ribociclib data.[4] We're also going to get our first look at some good phase 3 data with abemaciclib.[5] That's going to set up some important questions for future studies. How are these agents similar? How are they different? Does switching from one to the other or continuing CDK4/6 inhibition after progression make any sense? Does that provide any benefit to our patients? Is there a reason to choose one over the other? We won't have answers to those questions, but we're going to see a lot of interesting data with these agents for years to come.

It's going to be an exciting, data-packed year for us at ASCO. Hope to see you there.

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