Dr. Neeraj Agarwal and Dr. Rana McKay discuss promising studies in GU cancers featured at the 2024 ASCO Annual Meeting that highlighted improved outcomes in urothelial carcinoma, improved survival in renal cell carcinoma, and the role of ctDNA as a potential biomarker for predicting outcomes.
TRANSCRIPT
Dr. Neeraj Agarwal: Hello and welcome to the ASCO Daily News Podcast. I'm Dr. Neeraj Agarwal, your guest host of the ASCO Daily News Podcast today. I am the director of the Genitourinary Oncology Program, a professor of medicine at the University of Utah's Huntsman Cancer Institute, and editor-in-chief of the ASCO Daily News.
I am delighted to welcome Dr. Rana McKay, a GU medical oncologist and associate professor at the University of California San Diego. Today, we'll be discussing some key GU abstracts featured at the 2024 ASCO Annual Meeting.
Our full disclosures are available in the transcript of this episode.
Rana, we're thrilled to have you on the podcast today to share your insights on key advances in GU oncology from ASCO24.
Dr. Rana McKay: Thank you so much, Neeraj; it's a pleasure to be here.
Dr. Neeraj Agarwal: So, Rana, let's start with some bladder cancer abstracts. Could you tell us about Abstract 4503, titled "Impact of exposure on outcomes with enfortumab vedotin in patients with locally advanced or metastatic urothelial cancer"?
Dr. Rana McKay: Of course, I would be delighted to. First, I would like to remind our listeners that enfortumab vedotin (EV) was approved as a monotherapy for the treatment of locally advanced or metastatic urothelial cancer based on the results of EV-201 and EV-301 trials. In these pivotal studies, EV was initiated at a dose of 1.25 mg/kg, and dose modifications, such as reductions and interruptions, were used to manage adverse events. In the abstract presented at ASCO 2024, Dr. Daniel Petrylak and colleagues conducted a post-hoc exploratory analysis to evaluate the association between EV plasma exposure and outcomes. They used multiple pharmacokinetic samples collected during the first two cycles and pre-dose samples from 3 EV monotherapy studies, namely EV-101, EV-201, and EV-301, that were conducted in patients with previously treated locally advanced or metastatic urothelial carcinoma. Dose reductions to 1 mg/kg were required in 42.1% and 35.1% of patients in the EV-201 and EV-301 trials, respectively, and reductions to 0.75 mg/kg were required in 13.6% and 11.1% in the EV-201 and EV-301 trials, respectively. Higher EV exposure during the first two cycles was associated with a higher objective response rate. The ORR was 21.4% for the dose of 0.75 mg/kg, while it was 18.5% for the dose of 1.0 mg/kg. Interestingly, increasing the dosage to 1.25 mg/kg improved the ORR, which ranged from 40 to 51.1% across various studies. In the EV-301 trial, when comparing the efficacy of EV to chemotherapy, EV improved PFS and OS across all dose quartiles, and there was no evidence that recommended dose modifications impacted long-term efficacy outcomes.
Dr. Neeraj Agarwal: Thank you, Rana, for this great summary. I would like to add that the meticulously conducted pharmacokinetic studies demonstrated that serum levels of EV correlated with responses. Importantly, patients who had to decrease the dose did not experience compromised outcomes as EV improved PFS and OS outcomes vs chemotherapy in across all exposure quartiles in the EV-301 trial where EV was compared with chemotherapy. These findings highlight the need to start at the recommended dose of 1.25 mg/kg and reduce it, if necessary, however, clinicians should not start at a lower dose.
Dr. Rana McKay: I totally agree with you, Neeraj. Now, moving on to a different setting in bladder cancer, what can you tell us about LBA4517, titled "Perioperative sacituzumab govitecan alone or in combination with pembrolizumab for patients with muscle-invasive urothelial bladder cancer: SURE-01/02 interim results"?
Dr. Neeraj Agarwal: Of course! So, SURE was a multicohort, open-label, phase 2 study in patients with muscle-invasive bladder cancer assessing sacituzumab govitecan as a neoadjuvant therapy either alone in SURE-01 or as a combination with pembrolizumab followed by adjuvant pembro in SURE-02 in a flexible design allowing a bladder-sparing approach. In the abstract presented at ASCO 2024, Dr. Antonio Cigliola and colleagues report interim results of the SURE-01 study. Patients with cT2-4N0M0 urothelial carcinoma who were ineligible for or refused cisplatin-based neoadjuvant chemotherapy were planned to receive 4 cycles of neoadjuvant sacituzumab govitecan at a dose of 10 mg/kg followed by radical cystectomy.
An extensive assessment was performed at baseline and after the 4 cycles for response assessment. Patients with clinical complete response defined with negative MRI, cystoscopy and ctDNA assays refusing radical cystectomy were offered redo transurethral resection of the bladder tumor or repeat TURBT followed by observation in the absence of viable high-grade tumor in the bladder. The primary endpoint was pathological complete response rate, while secondary endpoints included pathological downstaging rate and safety. After the first 8 patients were enrolled, the protocol was amended due to the occurrence of grade 3 and 4 neutropenia and diarrhea in 75% and 50% of patients, respectively, and 2 deaths – one of which was deemed to be treatment-related due to sepsis. Key protocol changes included the reduction of the dose of sacituzumab govitecan to 7.5 mg/kg, the introduction of G-CSF as primary prophylaxis, and the exclusion of patients at high risk of febrile neutropenia per ASCO guidelines.
Among 21 patients who received at least one cycle of sacituzumab govitecan and included in the intention-to-treat population, 47.6% had a complete pathological response, and 52.4% had pathological downstaging. 11 patients underwent radical cystectomy, while 7 received repeat-TURBT due to complete clinical response or patient preference. Regarding the safety profile, grade 3 or more adverse events occurred in 42.5% of patients. Treatment-related adverse events leading to dose interruptions or discontinuations were more common before the protocol amendment. It is noteworthy that 3 patients died after treatment discontinuation, with one deemed treatment-related, as previously mentioned.
Dr. Rana McKay: Thank you, Neeraj, for a great summary. The pathological complete responses observed show promising activity for sacituzumab govitecan as a neo-adjuvant therapy and a window for bladder-sparing approaches, which is definitely exciting news for our patients! However, although the 3 deaths encountered in a neo-adjuvant setting could be concerning, the improvement of the safety profile after protocol amendments is reassuring and supports the continuation of the study.
Dr. Neeraj Agarwal: Before wrapping up the bladder cancer section, would you like to share your insights with our listeners on Abstract 4518, titled "Quantitative circulating tumor DNA (ctDNA) assessment in patients with advanced urothelial carcinoma treated with pembrolizumab or platinum-based chemotherapy from the phase 3 KEYNOTE-361 trial"?
Dr. Rana McKay: Sure. So, the KEYNOTE-361 trial was a randomized phase 3 study with 3 arms that included pembrolizumab plus chemotherapy, pembrolizumab monotherapy, or chemotherapy alone in patients with previously untreated advanced urothelial carcinoma. The results showed that neither the combination of pembrolizumab plus chemotherapy nor pembrolizumab monotherapy improved survival outcomes compared to the chemotherapy arm.
So, in this exploratory analysis presented at ASCO24, Dr. Tom Powles and colleagues sought to assess the role of ctDNA as a potential biomarker between the pembrolizumab monotherapy arm and the chemotherapy arm. Tumor tissue mutations were evaluated using whole exome sequencing, and plasma ctDNA was assessed with the Guardant 360 assay. Changes in ctDNA from pre-treatment cycle 1 to on-treatment cycle 2, so 3 weeks post-baseline assessment, were quantified by the maximum variant allele frequency of tumor tissue-specific mutations.
Results showed that lower baseline ctDNA levels were associated with improved clinical outcomes of response in the pembrolizumab arm but not in the chemotherapy arm. This improvement in the pembrolizumab arm was also robust to adjustment for tumor mutational burden and PD-L1. Additionally, chemotherapy led to a ctDNA clearance rate of 41% compared to 11% in the pembrolizumab arm. Patients who had a large ctDNA reduction with pembrolizumab had significantly improved outcomes compared to those achieving a large reduction with chemotherapy with a hazard ratio of 0.25. However, this did not replicate in patients who did not achieve a large reduction, as these patients had similar outcomes across both arms.
Let's switch gears to kidney cancer and start with Abstract 4508, reporting the final OS analysis from the JAVELIN Renal-101 trial. Neeraj, what would you like to tell us about this abstract?
Dr. Neeraj Agarwal: Well, as a quick reminder, the JAVELIN Renal-101 was a randomized phase 3 trial where patients with previously untreated advanced or metastatic clear cell renal cell carcinoma were randomized to receive either the combination of avelumab plus axitinib or sunitinib. In previous analyses, the combination of avelumab and axitinib significantly improved PFS compared to sunitinib and was subsequently approved by the FDA for the first-line treatment of patients with advanced RCC in 2019. This superiority in PFS was maintained across the different analyses; however, OS data remained immature. In the abstract presented at ASCO24 by Dr. Robert Motzer from Memorial Sloan Kettering Cancer Center and colleagues, the authors reported OS results at a median follow-up of around 73 months and a minimum of 68 months for all patients, which is the longest follow-up for any ICI-TKI combination in RCC. The final analysis in the overall population favored the combination of avelumab plus axitinib with a median OS of 44.8 months compared to 38.9 months with sunitinib, however, this did not reach statistical significance with a hazard ratio of 0.88. The PFS results and safety profile were consistent with previous analyses.
Dr. Rana McKay: Thank you, Neeraj, for such a nice overview of this abstract. These new data could make this regimen less optimal than other ICI-TKI combinations in the first-line mRCC setting.
Dr. Neeraj Agarwal: I concur, Rana. Moving on to perhaps one of the most exciting GU abstracts featured, Abstract 4506, titled "Circulating kidney injury molecule-1 biomarker analysis in IMmotion010: A randomized phase 3 study of adjuvant atezolizumab vs placebo in patients with renal cell carcinoma at increased risk of recurrence after resection." Rana, what are your thoughts on this abstract?
Dr. Rana McKay: Well, first, I would like to take a step back and remind our audience that in the IMmotion010 trial, patients with resected intermediate to high-risk RCC with clear cell and/or sarcomatoid component were randomized in a 1:1 ratio to receive either atezolizumab or placebo. Investigator-assessed disease-free survival, which was the primary endpoint, favored the atezolizumab arm but did not reach statistical significance. In the abstract featured at ASCO24, Dr. Laurence Albiges and colleagues build on data previously reported in the ASSURE and CheckMate 914 trials and report provocative findings regarding a molecule known as kidney injury molecule 1 or KIM-1, which is a type 1 membrane glycoprotein that has been identified as a minimally invasive potential peripheral blood circulating biomarker. The KIM-1 level of 86 pg/ml was identified as the optimized threshold for defining post-nephrectomy KIM-1 high vs KIM-1 low subgroups in the IMmotion010 trial. KIM-1 levels were measured at baseline or pre-treatment, at cycle 4 day 1, and at disease recurrence or discontinuation without disease recurrence. Baseline characteristics were balanced between the KIM-1 high and KIM-1 low groups, except perhaps for a slightly higher pathological stage in the KIM-1 high subgroup.
I would like to highlight 3 key takeaways from this abstract. First, KIM-1 high level was associated with significantly worse DFS with a hazard ratio of 1.75. Second, patients in the KIM-1 high subgroup receiving atezolizumab had a 28% reduction in the risk of recurrence or death compared to those receiving placebo, while those in the KIM-1 low subgroup had comparable outcomes across both treatment arms. Third, patients in the KIM-1 high subgroup receiving atezolizumab were significantly less likely to experience an on-treatment increase in KIM-1 levels, which was associated with worse DFS in both high and low KIM-1 subgroups, regardless of treatment arm. Thus, these findings support the use of KIM-1 as both a predictive and prognostic biomarker in patients with RCC.
Dr. Neeraj Agarwal: Yes, Rana, this is amazing data! I would like to add that these results warrant larger and, ideally, prospective studies to validate the utility of KIM-1 as a noninvasive biomarker for identifying minimal residual disease after nephrectomy and for predicting outcomes to immune checkpoint inhibitors.
Dr. Rana McKay: Also, in the field of biomarkers, 2 abstracts interrogating different biomarkers in a different setting, so in patients with advanced or metastatic RCC were presented. Neeraj, could you tell us more about these abstracts?
Dr. Neeraj Agarwal: Of course! I think you are referring to Abstracts 4504 and 4505. In abstract 4504, Dr. Toni Choueiri and colleagues sought to assess the clinical implications of different biomarkers in the CLEAR trial, which was a randomized phase 3 trial that led to the approval of the combination of pembrolizumab plus lenvatinib in the first-line mRCC setting. On the other hand, in abstract 4505, Dr. Brian Rini presented biomarker results in KEYNOTE-426, which was also a randomized phase 3 trial based on which the combination of pembrolizumab plus axitinib was approved in patients with mRCC. The authors in both trials sought to investigate the role of biomarkers in predicting treatment outcomes from 3 different angles. Starting with PD-L1 expression, the superiority of the combination arms over sunitinib was not impacted by PD-L1 status in both trials. Moving on to RCC driver gene mutations on whole exome sequencing, such as VHL, SETD2, PBRM1, and BAP1, ICI combination therapies improved outcomes regardless of mutation gene status, and this improvement was statistically significant with PBRM1 mutations in KEYNOTE-426 compared to wild-type PBRM1, but this did not replicate in the CLEAR trial. Finally, using transcriptomic signatures derived from RCC trials, especially the IMmotion 151 and JAVELIN Renal 101 trials, where 7 clusters or molecular subtypes were identified, the combination arms outperformed sunitinib in all clusters in both trials and the magnitude of this benefit differed across clusters.
Dr. Rana McKay: Thank you for this very interesting summary and comparison of the results of these 2 abstracts. These findings support the use of ICI-based combinations in all patients with mRCC as a first-line option. Although these abstracts could not identify specific biomarkers that could guide us clinicians in treatment selection, they provide very interesting biological insights on these molecular biomarkers that are, however, not yet clinically actionable.
Dr. Neeraj Agarwal: Very interesting point, Rana. Moving on to prostate cancer, let's start with abstract LBA5000 titled, "Cabazitaxel with abiraterone versus abiraterone alone randomized trial for extensive disease following docetaxel: The CHAARTED2 trial of the ECOG-ACRIN Cancer Research Group (EA8153)." Rana, what is your takeaway on this abstract?
Dr. Rana McKay: As a reminder to our audience, the CHAARTED2 trial was a randomized open-label phase 2 study that compared the combination of cabazitaxel and abiraterone to abiraterone alone in patients with mCRPC previously treated with ADT plus docetaxel in the hormone-sensitive setting. The primary endpoint was progression-free survival. After a median follow-up of 47.3 months, Dr. Christos Kyriakopoulos and colleagues reported in LBA5000 that patients receiving the combination of cabazitaxel plus abiraterone had a 27% reduction in the risk of progression or death. However, there was no significant difference in overall survival between the two arms, with a median OS of 25 months in the cabazitaxel+abiraterone arm and 26.9 months in the abiraterone arm, although the study was underpowered for this endpoint. Regarding the toxicity profile, the combination of cabazitaxel and abiraterone was overall well tolerated with more cytopenias, as expected.
Dr. Neeraj Agarwal: Very nice summary of this abstract, Rana. I would like to add that the treatment landscape of patients with mHSPC has evolved since the design of the study and now includes combination therapies of ADT + ARPI with or without docetaxel, and ADT + docetaxel is no longer a standard of care, which limits the applicability of these results in clinical practice today.
Dr. Rana McKay: Excellent point, Neeraj. Let's discuss Abstract 5001, titled "CYCLONE 2: A phase 3 study of abemaciclib with abiraterone in patients with metastatic castration-resistant prostate cancer".
Dr. Neeraj Agarwal: Sure! In the abstract featured at ASCO24, Dr. Matthew Smith and colleagues report the primary results of the CYCLONE 2 trial, which was a randomized phase 2/3 study that investigated the combination of abemaciclib plus abiraterone versus abiraterone monotherapy in patients with mCRPC. Stratification factors included radiographic progression at study entry, presence of measurable disease, and prior docetaxel for mHSPC. Part 1 of the study established the recommended phase 2 dose of abemaciclib at 200 mg twice daily. In part 2, patients were randomized to placebo or abemaciclib, and an adaptive interim analysis using prespecified criteria was performed and recommended the expansion of the study to part 3. The primary endpoint was investigator-assessed radiographic progression-free survival by RECIST 1.1 and PCWG3 criteria in the intention-to-treat population. At the time of the primary analysis, adding abemaciclib to abiraterone did not improve rPFS, with a hazard ratio of 0.83. The median rPFS was 22 months for the combination arm and 20.3 months for the abiraterone arm. The combination was well tolerated, and the safety profile was consistent with the known adverse events.
Dr. Rana McKay: So, the addition of abemaciclib to abiraterone did not improve outcomes in patients with mCRPC. These findings suggest that no further investigation is warranted for abemaciclib or CDK4/6 inhibitors in biomarker-unselected patients with prostate cancer.
Dr. Neeraj Agarwal: Rana, what's your take-home message on Abstract 5006, titled "Health-related quality of life results from PRESTO (AFT-19), a phase 3 randomized trial of intensification of androgen blockade in patients with high-risk biochemically relapsed castration sensitive prostate cancer"?
Dr. Rana McKay: So, as a reminder to our audience, the PRESTO trial was a randomized phase 3 study that assessed the effects of intensified androgen receptor blockade in patients with biochemically recurrent prostate cancer following local therapies. Patients with a PSA doubling time of less than 9 months and no evidence of metastatic disease were randomized to receive either 52 weeks of ADT alone, ADT plus apalutamide, or ADT plus apalutamide plus abiraterone. In their paper published earlier this year in the Journal of Clinical Oncology, the authors showed that patients receiving ADT plus apalutamide with or without abiraterone had significantly longer PSA-progression-free survival than those receiving ADT alone. In the oral presentation featured at ASCO24, Dr. Ronald Chen and colleagues report health-related quality of life outcomes that were assessed using various questionnaires or scales at baseline, at cycle 7, which is around 6 months on treatment, and at the end of treatment. Results showed that this intensified approach with apalutamide did not significantly increase severe adverse events, did not lengthen the time to testosterone recovery, and did not meaningfully increase common treatment-related symptoms such as hormonal symptoms, sexual dysfunction, hot flash interference, and fatigue. Importantly, additional intensification with abiraterone did not further improve PSA-PFS but did increase the rate of serious adverse events, lengthened the time to testosterone recovery, and increased hot flash interference.
Dr. Neeraj Agarwal: So, in conclusion, the PRESTO trial supports using intensified androgen blockade with apalutamide to improve PSA-PFS in patients with high-risk biochemically recurrent prostate cancer without compromising health-related quality of life. However, adding abiraterone did not offer additional benefits and increased side effects.
Dr. Rana McKay: Let's move on to LBA5002 titled, "A randomized, double-blind, placebo-controlled trial of metformin in reducing progression among men on expectant management for low-risk prostate cancer: The MAST (Metformin Active Surveillance Trial) study." Would you like to share your insights on this abstract with our listeners?
Dr. Neeraj Agarwal: Absolutely. MAST was a randomized, double-blinded, placebo-controlled trial that investigated the impact of metformin on the progression of low-risk localized prostate cancer in patients choosing to undergo active surveillance. Eligible patients had biopsy-proven, low-risk, localized prostate cancer diagnosed within the past 6 months, characterized by a Gleason score of less than 6 observed in less than one-third of the total cores, less than 50% positivity in any one core, a PSA level of less than 10 ng/ml, and a clinical-stage between T1c and T2a. Patients were randomized in a 1:1 ratio to receive either metformin 850 mg twice daily or placebo for three years. All patients underwent repeat prostate biopsy at 18 and 36 months. The primary endpoint was time to progression, defined as the earliest occurrence of primary prostate cancer therapy, such as prostatectomy, radiation, hormonal therapy, or pathological progression on subsequent biopsies, which was defined as more than 1/3 of total cores involved, at least 50% of any one core involved, or Gleason pattern 4 or higher. The study included 407 patients, with 204 receiving metformin and 203 receiving a placebo. Results presented by Dr. Anthony Joshua showed no statistically significant difference in progression-free survival, including therapeutic and pathologic progression, with an unadjusted hazard ratio of 1.08. Interestingly, there was a signal that patients with a BMI more than 30 had a detriment to taking metformin with a higher risk of progression compared to those receiving placebo with an unadjusted HR of 2.39 and a p-value of 0.01.
Dr. Rana McKay: I would like to add that this study showed that metformin use does not prevent the progression of low-risk localized prostate cancer on active surveillance and could represent a potential detriment for patients with high BMI at study entry.
Dr. Neeraj Agarwal: Yes, Rana, I concur. Any final remarks before we conclude today's podcast?
Dr. Rana McKay: Thank you, Neeraj; it's been wonderful being here with you today and you having me on the podcast to highlight these important advances and the amazing work that many investigators are conducting and the patients who were involved in the context of these trials. It's really excellent to see these updated results.
Dr. Neeraj Agarwal: Before we wrap up this podcast, I would like to say that we have reviewed a selection of abstracts addressing prostate, bladder, and kidney cancer, which are significantly impacting our medical practices now and in the near future. Rana, thank you for sharing your insights today. These updates are undoubtedly exciting for the entire GU oncology community, and we greatly appreciate your valuable contribution to the discussion. Many thanks.
And thank you to our listeners for joining us today. You will find links to the abstracts discussed today on the transcript of this episode. Finally, if you value the insights that you hear on the ASCO Daily News Podcast, please take a moment to rate, review, and subscribe wherever you get your podcasts.
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Disclosures:
Dr. Neeraj Agarwal:
Consulting or Advisory Role: Pfizer, Bristol-Myers Squibb, AstraZeneca, Nektar, Lilly, Bayer, Pharmacyclics, Foundation Medicine, Astellas Pharma, Lilly, Exelixis, AstraZeneca, Pfizer, Merck, Novartis, Eisai, Seattle Genetics, EMD Serono, Janssen Oncology, AVEO, Calithera Biosciences, MEI Pharma, Genentech, Astellas Pharma, Foundation Medicine, and Gilead Sciences
Research Funding (Institution): Bayer, Bristol-Myers Squibb, Takeda, Pfizer, Exelixis, Amgen, AstraZeneca, Calithera Biosciences, Celldex, Eisai, Genentech, Immunomedics, Janssen, Merck, Lilly, Nektar, ORIC Pharmaceuticals, Crispr Therapeutics, Arvinas
Dr. Rana McKay:
Consulting or Advisory Role: Janssen, Novartis, Tempus, Exelxis, Pfizer, Bristol-Myers Squibb, Astellas Medivation, Dendreon, Bayer, Sanofi, Merck, Vividion, Calithera, AstraZeneca, Myovant, Caris Life Sciences, Sorrento Therapeutics, AVEO, Seattle Genetics, Telix, Eli Lilly, Pfizer, Bayer, Tempus