Systemic Therapy in Patients with Metastatic Castration-Resistant Prostate Cancer Guideline Update

Dr. Rohan Garje shares the updated recommendations for the ASCO guideline on systemic therapy for patients with metastatic castration-resistant prostate cancer. He discusses the systemic therapy options for patients based on prior therapy received in the castration-sensitive and non-metastatic castration-resistant settings. He emphasizes personalizing treatment choices for each individual, considering patient-specific symptoms and signs, treatment-related toxicities, potential drug interactions, cost, and access. He also reviews recommendations on response assessment. The conversation wraps up with a discussion of potential future updates to this guideline, as the guideline transitions into a "living guideline" on mCRPC.

Read the full guideline update, "Systemic Therapy in Patients with Metastatic Castration-Resistant Prostate Cancer: ASCO Guideline Update".

Transcript

This guideline, clinical tools, and resources are available at www.asco.org/genitourinary-cancer-guidelines. Read the full text of the guideline and review authors' disclosures of potential conflicts of interest in the Journal of Clinical Oncology.

Brittany Harvey: Hello and welcome to the ASCO Guidelines Podcast, one of ASCO's podcasts delivering timely information to keep you up to date on the latest changes, challenges and advances in oncology. You can find all the shows, including this one at asco.org/podcasts.

My name is Brittany Harvey and today I'm interviewing Dr. Rohan Garje from Miami Cancer Institute Baptist Health South Florida, lead author on, "Systemic Therapy in Patients with Metastatic Castration-Resistant Prostate Cancer: ASCO Guideline Update."

Thank you for being here today, Dr. Garje.

Dr. Rohan Garje: Absolutely. Thank you so much for having me, Brittany.

Brittany Harvey: And then before we discuss this guideline, I'd like to note that ASCO takes great care in the development of its guidelines and ensuring that the ASCO Conflict of Interest Policy is followed for each guideline. The disclosures of potential conflicts of interest for the guideline panel, including Dr. Garje, who has joined us here today, are available online with the publication of the guideline in the Journal of Clinical Oncology, which is linked in the show notes.

So then, to start on the content of this guideline, first, could you provide us an overview of the purpose of this guideline update?

Dr. Rohan Garje: Sure. So ASCO has guidelines for prostate cancer and the specific guideline which we have updated for metastatic castrate-resistant prostate cancer was originally published in 2014. It's almost a decade. It's been a long time due for an update. Over the last decade, we have seen a lot of advances in the treatment of prostate cancer, specifically with regards to genomic testing, newer imaging modalities, and also the treatment landscape. Now we have newer options based on genomic targets such as PARP inhibitors, we have radiopharmaceuticals, a newer variant of chemotherapy, and also some specific indications for immunotherapy which were not addressed previously. Because all these advances have been new, it was really important for us to make an update. In 2022, we did make a rapid update with lutetium-177, but these additional changes which we have seen made it an appropriate time frame for us to proceed with a newer guideline.

Brittany Harvey: Absolutely. It's great to hear about all these advances in the field to provide new options.

So I'd like to next review the key recommendations from this guideline. So let's start with the overarching principles of practice that the panel outlined. What are these key principles?

Dr. Rohan Garje: As a group, all the panel members came up with some ground rules: What are necessary for all our patients who are being treated for metastatic CRPC? First, the founding aspect was a definition for what is metastatic CRPC. So we defined metastatic CRPC as castrate level of testosterone with evidence of either new or progressive metastatic disease on radiological assessments or patients who have two consecutive rising PSAs in the setting of existing metastatic disease. We also emphasized on the need for germline and somatic testing for patients with metastatic prostate cancer at an earliest available opportunity because it is critical to select appropriate treatment and also right treatment for patients at the right time. And we actually have a concurrent guideline which addresses what genes to be tested and the timing. The other principles are patients should continue to receive androgen deprivation therapy or undergo surgical castration to maintain castrate level of testosterone.

Now the key aspect with these guidelines is personalizing treatment choices. As you can see the evolution of treatment options for prostate cancer, the drugs that were initially developed and approved for prostate cancer were primarily in castrate-resistant settings, but now most of these drugs are being utilized in castrate-sensitive. So, when these patients develop castration resistance, the challenges are there are no appropriate particular drug-specific guidelines they meet. So, it's very important for the clinicians to be aware of what treatments have been received so far prior to castration resistance so that they can tailor the treatment to patient specific situations. In addition, prior to choosing a therapy, it is important for the physicians to consider patient specific symptoms or signs, treatment-related toxicities, potential drug interactions, cost, and also access to the drugs. There may be multiple treatment options available for the patients, but for a patient specific scenario, there may be a drug that may be more promising than the others. So, it is important to tailor the drug choices based on patients' unique circumstances.

The panel also recommends to early integrate palliative and supportive care teams for symptom management and also discuss goals of care with the patient as each patient may have unique needs and it's important for physicians to address those concerns upfront in the care. The panel also suggests patients to receive RANK ligand inhibitors such as denosumab or bisphosphonates such as zoledronic acid to maintain the bone strength to prevent skeletal-related events.

Finally, I would like to also emphasize this point about the lack of randomized clinical trial data for optimal sequencing of therapies for patients with metastatic CRPC. As I previously alluded, we have taken into account all ongoing clinical trials, prior published data, and came up with a format of preferred drugs based on prior treatments and, I think, by following these several clinical principles which I just mentioned, we can optimally choose and utilize best treatments for patients with metastatic CRPC.

Brittany Harvey: Absolutely. These principles that you just outlined are important for optimal patient care, and then I want to touch on one of those things. You talked importantly about the treatments received so far. So in the next set of recommendations, the role of systemic therapy was stratified by the prior therapy received in the castration-sensitive and non-metastatic castration-resistant setting. So starting with what does the panel recommend for patients who are previously treated with androgen deprivation therapy alone in these previous settings and whose disease has now progressed to metastatic castration-resistant prostate cancer?

Dr. Rohan Garje: There are multiple treatment options based on prior treatment received. So for patients who received only ADT for their castration-sensitive disease, the panel strongly urges to get HRR testing to check for homologous recombinant repair related changes, specifically for BRCA1 and BRCA2 mutations, because we have three studies which have really shown significant clinical benefit for patients who have BRCA1 and BRCA2 mutations with drugs such as the combination of talazoparib and enzalutamide or olaparib with abiraterone or niraparib with abiraterone. Unless we test for those mutations, we'll not be able to give these agents upfront for the patients. In the HRR testing, if patients have HRR alterations but they are in genes which are non-BRCA, the guideline panel recommends to utilize talazoparib and enzalutamide based combination therapies. Now, if they don't have HRR alterations then there are multiple treatment choices available. It could either include androgen receptor pathway inhibitors such as abiraterone with prednisone. We could also consider docetaxel chemotherapy. The alternate choices for androgen receptor pathways include enzalutamide or the newer agents such as apalutamide and docetaxel. So, as you can see there are multiple options available, but the panel definitely emphasizes to test for HRR testing because this gives patients access to more precision therapies at this point.

There may be various scenarios where a unique drug may be available for a specific patient situation. For example, patients who have very limited disease burden and may have one or two metastatic lesions, after a multidisciplinary discussion, targeted local therapies such as radiation or potentially surgery could also be offered. In select patients who have very indolent disease where they are castrate-resistant based on slow rising PSA, low-volume disease or asymptomatic disease can consider sipuleucel-T. And in patients who have bone-only metastatic disease, we could also consider radium-223, which is primarily now utilized for patients who have symptomatic bone disease.

Brittany Harvey: Great. I appreciate you reviewing all those options and talking about how important it is to tailor treatment to the individual patient.

So then the next category of patients, what is recommended for those who have been previously treated with ADT and an androgen receptor pathway inhibitor and whose disease has now progressed to metastatic castration-resistant prostate cancer?

Dr. Rohan Garje: So for patients who received ADT along with an androgen receptor pathway inhibitor, which we consider would be a most common cohort because most patients now in castration-sensitive setting are receiving androgen receptor pathway inhibitor. It was different in the past where five or six years back ADT alone was the most common treatment, but fortunately, with enough awareness and education, treatment choices have improved. Patients are now receiving ADT and ARPI as the most common choice of drug. Once again, at this point the panel emphasizes to consider HRR testing in there is enough data for us to suggest that patients who have alterations in the HRR pathway definitely will benefit with the PARP inhibitor. You know the multiple options, but specifically we speak about olaparib. And then if they are HRR-negative, we prefer patients receive agents such as docetaxel or if they are intolerant to docetaxel, consider cabazitaxel chemotherapy, options such as radium-223, and if they have a specific scenario such as MSI-high or mismatch repair deficiency, pembrolizumab could also be considered.

The panel also discussed about the role of a second ARPI agent. For example, if patients progressed on one androgen receptor pathway inhibitor, the second androgen receptor pathway inhibitor may not be effective and the panel suggests to utilize alternate options before considering androgen receptor pathway inhibitor. There may be specific scenarios where a second ARPI may be meaningful, specifically, if alternate choices are not feasible for the concern of side effects or toxicities or lack of access, then a potential ARPI could be considered after progression on ARPI, but the panel definitely encourages to utilize alternate options first.

Brittany Harvey: Great. Thank you for outlining those options as well for those patients.

So then the next category, what is recommended for patients who have been previously treated with ADT and docetaxel?

Dr. Rohan Garje: For patients who received ADT and docetaxel and were never treated with androgen receptor pathway inhibitors, the panel again emphasizes on HRR testing. If they have BRCA1 and 2 mutations, the combination therapies of talazoparib with enzalutamide, olaparib with abiraterone, or niraparib with abiraterone are all good choices. If they don't have BRCA mutations but they have other HRR mutations, the panel suggests to potentially utilize talazoparib with enzalutamide. And if they do not have any HRR alterations, the options could include androgen receptor pathway inhibitors such as abiraterone or enzalutamide.

I want to emphasize that these are preferred options, but not the only options. As you can see, there are multiple options available for a particular clinical situation - so the ability of the physicians to access particular combinations, the familiarity of those drugs or the patient's unique situation where they have other medications which can potentially interact with a choice of agents. So I think based on access, based on cost and patients' concurrent illness with potential drug interactions can make one particular combination of therapy better over the other options.

Brittany Harvey: Absolutely. That's key to keep in mind that access, contraindications, and cost all play a role here.

So then the next set of recommendations. What are the key recommendations for patients who have previously been treated with ADT, an androgen receptor pathway inhibitor, and docetaxel who now have mCRPC?

Dr. Rohan Garje: Yes. In this group, the options remain, again, broad. We utilize PSMA imaging here specifically and if they are positive on PSMA imaging, lutetium-177 is a good option. If they do not have PSMA-positive disease on PSMA imaging but if they have HRR alterations, olaparib could be utilized. And if they are negative on PSA imaging, they don't have HRR alterations, then alternate options could include cabazitaxel, radium-223. And if they have MSI-high or deficiency in mismatch repair, pembrolizumab could be utilized in this setting.

Brittany Harvey: Thank you for outlining those options as well.

So then next the panel addressed treatment options for de novo or treatment emergent small cell neuroendocrine carcinoma of the prostate. What are those key recommendations?

Dr. Rohan Garje: Yes. This is a very high unmet need group because there are limited clinical trials, especially prospective clinical trials addressing treatment options for this group. Most of our current guidelines are always an extrapolation from lung small cell cancer based guidelines, but the panel recommends to utilize cisplatin or carboplatin along with etoposide as a preferred choice for this group. Also, an alternate option of carboplatin along with cabazitaxel could be considered for this cohort.

The panel also encourages participation in clinical trials. There are numerous trials ongoing now in smaller phase studies and I think it's important for patients to consider these trials as well, because this will give them access to newer agents with potential biological targets. In addition to these agents in specific scenarios or potentially case by case basis, because we don't have prospective data, so we have made it as a select case by case basis to consider adding immunotherapy along with platinum-based chemotherapy followed by maintenance immunotherapy, which is currently a standard of care in small cell lung cancer. But the data is so limited in prostate cancer, so the panel suggested that it has to be a case by case basis only. The alternate options also include lurbinectedin, topotecan, tarlatamab upon progression on platinum-based chemotherapy.

Brittany Harvey: Yes. It's important to have these recommendations in these unique situations where there is really a lack of data.

So then the final set of recommendations I'd like to cover, what does the panel recommend for how clinicians should assess for response while patients are on systemic therapy and what scans are recommended for this response assessment?

Dr. Rohan Garje: Yes. Again, this is another strong emphasis of the panel for global assessment of the patients. Traditionally, patients and physicians per se are heavily reliant on PSA as an accurate marker for response. This is in fact true in earlier phases of prostate cancer either in castrate-sensitive setting or localized prostate cancer setting. But as patients evolve into castrate-resistant, we don't want to heavily rely on PSA alone as a marker of response. The panel suggests to incorporate clinical response, radiological response, and also include PSA as a component, but not just rely primarily on PSA. So the panel also suggests that patients should get a bone scan and a CT scan every three to six months while on treatment to assess for appropriate response or for progression.

And now one key important aspect, we are all aware about the evolving role of PSMA-based imaging with several of these new agents that are currently available. We do acknowledge these scans definitely have an important role in the care for patients with metastatic prostate cancer. Currently, the utility is primarily to select patients for lutetium-based therapy and also in situations where the traditional scans such as technitium 99 bone scan or CT scan are equivocal, then a PSMA-based imaging can be helpful. Now we are also aware that there are newer studies coming up, prospective data coming up for the role of PSMA-based imaging for response assessment. We are hoping to update the guidelines if we get access to newer data, but currently we have not recommended the utility of PSMA-based imaging for response assessments.

Brittany Harvey: Understood. And I appreciate you describing where there is data here and where there's a lack of data to currently recommend. And we'll look forward to future updates of this guideline.

Coming back to – at the start you mentioned how much has changed since the last guideline update. So Dr. Garje, in your view, what is the importance of this update and how will it impact both clinicians and patients with metastatic castration-resistant prostate cancer?

Dr. Rohan Garje: The updated guidelines are designed to have a significant impact on clinical practice and also patient outcomes by providing clinicians with a comprehensive evidence-based framework for managing patients with metastatic CRPC. And also, by using these guidelines can make informed decisions, can select therapies tailored to patients' unique genomic status, clinical situation, where they are in the course of the cancer based on what they received previously. Also utilizing these guidelines, we can potentially improve patient outcomes, improve survival, and importantly have efficient use of healthcare resources.

Brittany Harvey: Absolutely. We're always looking for ways to improve patient outcomes and survival.

I want to wrap us up by talking a little bit about the outstanding questions in this field. So earlier you had mentioned about prospective data to come about PSMA PET scans, but what other outstanding questions are there for patients with metastatic castration-resistant prostate cancer? And what evidence is the panel looking forward to for future updates?

Dr. Rohan Garje: We do have now rapidly evolving data specifically about the utility of the radiopharmaceutical lutetium-177 prior to chemotherapy. We are hoping that with newer data we can make some changes to the guideline based on that. We are also looking at newer drugs that are coming up in the pipeline, for example, androgen receptor degraders. We are looking at data that might potentially help based on bispecific T-cell engagers and newer radiopharmaceuticals.

So I think in the next few years, we will definitely update all the guidelines again. But this time we are trying to do it more proactively. We are following a newer model. We are calling it as 'living guidelines' where we are actually utilizing week by week updates where we look at the literature and see if there is any potential practice impacting change or publication that comes up. And we are trying to incorporate those changes as soon as they are available. That way patients and practicing physicians can get the latest information available through the guidelines as well.

Brittany Harvey: That's great to hear. Yes, we'll await this data that you mentioned to continuously update this guideline and continue to improve patient outcomes for the future.

So Dr. Garje, I want to thank you so much for your time to update this guideline. It was certainly a large amount of recommendations, and thank you for your time today, too.

Dr. Rohan Garje: Thank you so much for having me here. And it's always nice talking to you.

Brittany Harvey: And finally, thank you to our listeners for tuning in to the ASCO Guidelines podcast. To read the full guideline, go to www.asco.org/genitourinary-cancer-guidelines. You can also find many of our guidelines and interactive resources in the free ASCO Guidelines app, which is available in the Apple App Store or the Google Play Store. If you have enjoyed what you've heard today, please rate and review the podcast and be sure to subscribe so you never miss an episode.

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