This interview, “Clinical Trial: Zytiga, Lynparza, + DNA Repair Defects,” is provided by Grand Rounds in Urology’s content partner, Prostatepedia.
Dr. Maha Hussain is the Genevieve Teuton Professor of Medicine in the Division of Hematology, Department of Medicine, and the Deputy Director of the Robert H. Lurie Comprehensive Cancer Center of the Northwestern University Feinberg School of Medicine.
Prostatepedia spoke with her about a clinical trial she’s running, BRCAAway, that looks at Zytiga (abiraterone) and Lynparza (olaparib) in metastatic castrate-resistant prostate cancer (mCRPC) patients with DNA repair defects. (The trial has a ClinicalTrials.gov Identifier of NCT03012321).
What can you tell us about the trial that you’re running looking at Zytiga (abiraterone) and Lynparza (olaparib)?
Dr. Maha Hussain: In prostate cancer, and specifically in mCRPC, data emerging from multiple resources, including the Stand Up To Cancer initiative from a few years ago, indicate that greater than 20% of mCRPC cancer harbor DNA repair pathway aberrations. These types of defects in the tumor will allow the patient to potentially be a candidate for PARP inhibitors. In this regard, PARP inhibitors have had a track record in ovarian and breast cancer.
They’re currently undergoing multiple clinical trials, including Phase III clinical trials in patients with advanced disease and in different settings of the disease.
A couple of years ago, we published data from an NCI-funded clinical trial where patients with mCRPC underwent a biopsy of their metastatic cancer. The patients were then stratified by the presence or absence of ETS gene fusion and randomized to Zytiga (abiraterone) and prednisone with or without a PARP inhibitor called veliparib.
As part of that study, we also looked at other tumor genomics when extra tissue was available. We discovered that the patients who had tumors with DNA repair defects seemed to respond much better to treatment with Zytiga (abiraterone) with or without veliparib as opposed to the patients who did not have that. This is not something that anyone knew before. After we had published our data, the Johns Hopkins team published data they had on patients who had undergone germline testing and who had received Zytiga (abiraterone) or Xtandi (enzalutamide). They reported similar observations.
This leads me to the current trial, which we call BRCAAway. BRCAAway is a prospective clinical trial for patients who have developed mCRPC for which they have not yet received any specific treatment. Patient will undergo a biopsy, unless they have previous tissue available from either the primary or metastatic disease, and the tissue will then be evaluated for the presence of specific DNA repair defect alterations. Per the US FDA guidance, patients who have BRCA1, BRCA2, and/or ATM are randomly assigned to either Zytiga (abiraterone) + prednisone, Lynparza (olaparib), or combination Zytiga (abiraterone) + prednisone and Lynparza (olaparib). Any patient whose tumors have other DNA repair defects (not BRCA1, BRCA2, or ATM) are enrolled into an exploratory arm where they will receive Lynparza (olaparib). Lynparza (olaparib) is provided by the study. The patients who are randomized to the arm of the Zytiga (abiraterone) or Lynparza (olaparib) can cross over to the other treatment if their cancer is progressing; i.e., if a patient who is randomized to Zytiga (abiraterone) and prednisone and then develops progression of the cancer is interested and his physician deems it appropriate, he can switch over to Lynparza (olaparib). The same is the case for patients who are randomized to Lynparza (olaparib) if they progress on frontline Lynparza (olaparib), they can switch to Zytiga (abiraterone) and prednisone per standard-of-care.
Are you assuming that these patients have already been tested for BRCA1, BRCA2, and ATM, or will you be testing for that?
Dr. Hussain: So long as it was done in a certified and appropriate lab, we can accept the data for patients who have been tested. The study covers a biopsy and the genomic testing for the patients.
Are there any fees associated, or is everything covered?
Dr. Hussain: Anything that’s standard-of-care is billed to insurance. Anything that is a research procedure, as in the biopsy and the genomics testing, is covered by the study. The Lynparza (olaparib) is provided by the study, but the Zytiga (abiraterone) is not because that’s part of standard-of-care. All of these tests to assess the cancer, assess tolerance, and assess the cancer progression in terms of scans, things like blood work or anything for safety assessment, per CMS rules, are billed to insurance.
How many patients have you already enrolled, and how many are you looking to enroll?
Dr. Hussain: In the arm with the BRCA1, BRCA 2, and ATM, we need 60 patients. We’re about halfway there. We have enrolled 40 patients to date. For the exploratory arm, we have expanded our limit, and we’re growing that arm. So far, we have plenty of room to accrue more patients.
How many sites do you have?
Dr. Hussain: We currently have 15 active sites.
That’s a lot.
Dr. Hussain: It’s a lot of sites, but as I’m sure patients appreciate, part of it is that by the time we see an eligible patient, they have to have the specific mutations, whether it’s on new tests or based on previous tissue. When we test, it’s roughly one in five who will likely be positive. Of course, they have to qualify by other criteria, so we have to screen many patients. We’re on track as we forecasted, and we’re hopeful to finish enrollment by a year from now. We also hope to have some important data to share.
Wow! That’s fast.
Dr. Hussain: Of course we need adequate follow-up to assess clinical benefit and its duration. I’m thinking 2020 will be the end of the study, and if there are signals earlier, we will be reporting the data. The Prostate Cancer Clinical Trial Consortium (PCCTC) is acting as the coordinating CRO. The institutional review board (IRB) of record is Northwestern University IRB. If you’re interested in learning more, please visit https://clinicaltrials.gov/ct2/show/NCT03012321 or email cancertrials@ northwestern.edu.
Is there anything else you want patients to know about this particular trial or about the context in which it’s occurring?
Dr. Hussain: This and other clinical trials are important options for patients to consider. Clearly, they have access to regular standard-of-care treatment. The hope is that we can do better than standard-of-care. We are also trying to validate earlier observations that I mentioned regarding whether the patients who have DNA repair defects have better response to Zytiga (abiraterone) and how does this response compare to Lynparza (olaparib) versus the combination.
Lynparza (olaparib) is a drug that’s available on the market for breast and ovarian cancer, so there’s a fair amount of experience with it. It is not yet FDA approved for prostate cancer, but we have a reasonable understanding for the potential side effects. Certainly, there are multiple clinical trials that are looking at it and other PARP-inhibitors in prostate cancer.
Zytiga (abiraterone) is standard-of-care and FDA approved. It’s been around for many years. All treating oncologists should be very familiar with it and how to monitor and what to expect.
It looks like an exciting trial.
Dr. Hussain: We are very excited. What is clear from the experience with prostate cancer is that one size does not fit all, this is one of the first examples of precision medicine in front line mCRPC. Our goal is to better personalize care and significantly impact disease outcomes.
The patient is our partner. We cannot succeed and deliver better treatments to patients without their partnership, so we are very grateful to them for their participation.