Therapy With Metronomic Cyclophosphamide (mCyc) for Previously-Treated Metastatic Castrate-Resistant Prostate Cancer (mCRPC)

INTRODUCTION

Despite the introduction of various novel therapies for management of metastatic castrate resistant prostate cancer (mCRPC) in recent decades, available treatment options are finite and remain limited. Multiple historical studies have demonstrated activity and a favorable toxicity profile of oral metronomic cyclophosphamide (mCyc) in prostate cancer (PCa). Unlike the cytotoxic immunosuppressive effects of high-dose intravenously-administered cyclophosphamide, continuous low doses of oral mCyc have a unique immune-stimulatory mechanism of action.

MATERIALS AND METHODS

This is a retrospective, multi-institution study of men with 43 patients with mCRPC treated mCyc. Patient demographic information as well as clinical, pathologic, and genomic characteristics of their PCa were extracted. The primary endpoint was the rate of PSA decline by ≥ 50% (ie, PSA50). Additional efficacy and toxicity data as well as cost analysis compared to other commonly used agents in mCRPC was obtained.

RESULTS

PSA50 was noted in 20.9% of patients, while an additional 25.6% patients achieved < PSA50 and 6.9% reported improvement in prostate cancer-related symptoms without any PSA reduction. Meanwhile, 9.3% of patients required mCyc dose reduction, 11.6% needed dose interruption due to toxicity, and no treatment discontinuations due to toxicity were observed. mCyc was also cost effective compared to other agents commonly used in mCRPC.

CONCLUSIONS

Despite the small sample size and retrospective nature of this dataset, mCyc demonstrated promising rapid activity and a tolerable toxicity profile in a heavily pretreated mCRPC population with aggressive clinical, pathologic, and genomic disease features.

Three- and Seven-month Prostate-specific Antigen Levels as Prognostic Markers for Overall Survival in Metastatic Hormone-sensitive Prostate Cancer: Results from SWOG S1216, a Phase 3 Randomized Trial of Androgen Deprivation Plus Orteronel or Bicalutamide

BACKGROUND

A robust decrease in prostate-specific antigen (PSA) in response to androgen deprivation therapy (ADT) has been evaluated as a prognostic factor in patients with metastatic hormone-sensitive prostate cancer (mHSPC) since 2006, but the treatment of mHSPC has since evolved to include intensified therapy.

OBJECTIVE

We assessed the association of PSA levels at 3 (PSA-3mo) and 7 (PSA-7mo) mo with overall survival (OS) in patients with mHSPC treated with ADT combined with either bicalutamide or orteronel in the S1216 phase 3 clinical trial.

DESIGN, SETTING, AND PARTICIPANTS

PSA responses to treatment of patients in the S1216 trial were categorized as: complete response (CR) if PSA was ≤0.2 ng/ml, partial response if PSA was >0.2 and ≤4 ng/ml, and no response (NR) if PSA was >4 ng/ml.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

A Cox analysis (adjusted for treatment arm and three stratification factors: performance status, severity of disease, and early vs late induction) was used for OS association. While PSA-7mo association was a prespecified objective, PSA-3mo association was also evaluated.

RESULTS AND LIMITATIONS

A total of 1251 and 1231 patients from the S1216 study were evaluable for PSA-3mo and PSA-7mo, respectively. A PSA-7mo CR was associated with improved OS compared with NR (HR: 0.20; p < 0.0001). A PSA-3mo CR showed a similar association to NR (HR: 0.34; p < 0.0001). The association of a PSA response with survival did not differ by treatment arm at either time point.

CONCLUSIONS

The PSA-3mo and PSA-7mo responses were strongly associated with OS; taken with other emerging prognostic biomarkers, these markers may allow for early identification of patients at the highest risk of death, aid with counseling in clinical practice, and permit design of future clinical trials targeting these patients.

PATIENT SUMMARY

A low prostate-specific antigen level at 3 or 7 mo after starting treatment for metastatic hormone-sensitive prostate cancer predicts longer survival regardless of the first treatment given with androgen deprivation therapy.

Markers of bone metabolism and overall survival in men with bone-metastatic hormone sensitive prostate cancer (HSPC): A subset analysis of SWOG S1216, a phase III trial of androgen deprivation with or without orteronel

BACKGROUND

Circulating biomarkers of bone metabolism are significantly associated with overall survival (OS) in men with advanced prostate cancer. In the SWOG S1216 phase III trial, we showed that elevated bone biomarkers are significantly associated with an increased risk of death in hormone-sensitive prostate cancer (HSPC) regardless of the status of bone metastases, identifying three risk groups with differential OS outcomes based on bone biomarker status. Here we report the association of bone biomarkers with OS in men with HSPC and documented skeletal metastases as part of a planned subset analysis of S1216.

METHODS

Bone resorption [C-telopeptide (CTx); Pyridinoline (PYD)] and bone formation markers [C-terminal collagen propeptide (CICP); bone alkaline phosphatase (BAP)] were assessed in blood from men with bone metastatic HSPC. Patients were randomly divided into training (n = 238) and validation (n = 475) sets. In the training set, recursive partitioning that maximizes discrimination of OS was used to identify the dichotomous cut-point for each biomarker and for a combination of biomarker split points to define prognostic groups. In the validation set, Cox proportional hazards models were used to assess the impact of biomarkers on OS, adjusted for patient and tumor characteristics.

RESULTS

Of 1279 men, 713 had both baseline bone metastases and evaluable bone biomarkers. Patient characteristics were similar between the overall population and the subset with bone metastases. Elevated levels of CICP, CTX, and PYD were strongly prognostic for OS. Hazard ratios (95% CI) for OS adjusted for treatment arm and baseline clinical variables were: BAP-1.31 (0.93, 1.84), p = 0.12; CICP-1.58 (1.09, 2.29), p < 0.02; CTx - 1.55 (1.12, 2.15), p = 0.008; and PYD-1.66 (1.27, 2.217), p = 0.0002. There was no evidence of interaction between elevated biomarkers and treatment (all p > 0.2). Recursive partitioning algorithms identified four groups of patients with differential OS outcomes based on bone biomarkers, adjusted for baseline clinical variables, with median OS ranging from 2.3 years (highest risk group) to 7.5 years (lowest risk group).

CONCLUSIONS

In this planned S1216 subset analysis of men with HSPC and bone metastases, elevated serum markers of bone metabolism were significantly associated with worse OS. Bone biomarker levels alone and in combination with patient and tumor characteristics identify unique subsets of men with differential OS outcomes.

CLINICALTRIALS

GOV IDENTIFIER

NCT01809691.

Bone Biomarkers and Subsequent Survival in Men with Hormone-sensitive Prostate Cancer: Results from the SWOG S1216 Phase 3 Trial of Androgen Deprivation Therapy with or Without Orteronel

BACKGROUND

Bone biomarkers are strongly prognostic for overall survival (OS) in men with castration-resistant prostate cancer but not fully established for hormone-sensitive prostate cancer (HSPC).

OBJECTIVE

Bone biomarkers in HSPC were prospectively evaluated as part of a phase 3 study of androgen deprivation therapy ± the CYP17 inhibitor orteronel.

DESIGN, SETTING, AND PARTICIPANTS

Patients were randomly divided into training (n = 316) and validation (n = 633) sets. Recursive partitioning and Cox proportional hazard models were employed.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Bone resorption (C-telopeptide and pyridinoline) and bone formation markers (C-terminal collagen propeptide and bone alkaline phosphatase) were assessed from patient sera.

RESULTS AND LIMITATIONS

Of 1279 men, 949 had evaluable baseline bone biomarkers. Optimal cutoffs were identified to define elevated levels of each of the four biomarkers (all p < 0.05) that were associated with worse OS. After adjusting for clinical risk factors in the validation set, elevated bone biomarkers were statistically significantly associated with an increased risk of death (hazard ratios ranging from 1.37 to 1.92). Recursive partitioning algorithms applied to the training set identified three risk groups (low, intermediate, and poor) with differential OS outcomes (median OS: 8.2, 5.1, and 2.1 yr, respectively) based on combinations of bone biomarkers. These results were confirmed in the validation set.

CONCLUSIONS

In men with HSPC initiating androgen deprivation therapy, bone biomarkers are strongly and independently prognostic for OS. Bone biomarker levels alone or in combination with clinical covariates identify unique subsets of men with differential OS outcomes. These results validate the clinical value of bone biomarker assessment in the HSPC state, extending bone biomarker utility beyond the castration-resistant state.

PATIENT SUMMARY

In men with newly diagnosed metastatic prostate cancer, high levels of bone turnover biomarkers are associated with a shorter lifespan.

Prostate cancer and bone: clinical presentation and molecular mechanisms

Prostate cancer (PCa) is an increasingly prevalent health problem in the developed world. Effective treatment options exist for localized PCa, but metastatic PCa has fewer treatment options and shorter patient survival. PCa and bone health are strongly entwined, as PCa commonly metastasizes to the skeleton. Since androgen receptor signaling drives PCa growth, androgen-deprivation therapy whose sequelae reduce bone strength constitutes the foundation of advanced PCa treatment. The homeostatic process of bone remodeling - produced by concerted actions of bone-building osteoblasts, bone-resorbing osteoclasts, and regulatory osteocytes - may also be subverted by PCa to promote metastatic growth. Mechanisms driving skeletal development and homeostasis, such as regional hypoxia or matrix-embedded growth factors, may be subjugated by bone metastatic PCa. In this way, the biology that sustains bone is integrated into adaptive mechanisms for the growth and survival of PCa in bone. Skeletally metastatic PCa is difficult to investigate due to the entwined nature of bone biology and cancer biology. Herein, we survey PCa from origin, presentation, and clinical treatment to bone composition and structure and molecular mediators of PCa metastasis to bone. Our intent is to quickly yet effectively reduce barriers to team science across multiple disciplines that focuses on PCa and metastatic bone disease. We also introduce concepts of tissue engineering as a novel perspective to model, capture, and study complex cancer-microenvironment interactions.

Cisplatin-induced increase in heregulin 1 and its attenuation by the monoclonal ErbB3 antibody seribantumab in bladder cancer

Cisplatin-based combination chemotherapy is the foundation for treatment of advanced bladder cancer (BlCa), but many patients develop chemoresistance mediated by increased Akt and ERK phosphorylation. However, the mechanism by which cisplatin induces this increase has not been elucidated. Among six patient-derived xenograft (PDX) models of BlCa, we observed that the cisplatin-resistant BL0269 express high epidermal growth factor receptor, ErbB2/HER2 and ErbB3/HER3. Cisplatin treatment transiently increased phospho-ErbB3 (Y1328), phospho-ERK (T202/Y204) and phospho-Akt (S473), and analysis of radical cystectomy tissues from patients with BlCa showed correlation between ErbB3 and ERK phosphorylation, likely due to the activation of ERK via the ErbB3 pathway. In vitro analysis revealed a role for the ErbB3 ligand heregulin1-β1 (HRG1/NRG1), which is higher in chemoresistant lines compared to cisplatin-sensitive cells. Additionally, cisplatin treatment, both in PDX and cell models, increased HRG1 levels. The monoclonal antibody seribantumab, that obstructs ErbB3 ligand-binding, suppressed HRG1-induced ErbB3, Akt and ERK phosphorylation. Seribantumab also prevented tumor growth in both the chemosensitive BL0440 and chemoresistant BL0269 models. Our data demonstrate that cisplatin-associated increases in Akt and ERK phosphorylation is mediated by an elevation in HRG1, suggesting that inhibition of ErbB3 phosphorylation may be a useful therapeutic strategy in BlCa with high phospho-ErbB3 and HRG1 levels.

A Phase I Study of Combination Olaparib and Radium-223 in Men with Metastatic Castration-Resistant Prostate Cancer (mCRPC) with Bone Metastases (COMRADE)

Given that radium-223 is a radiopharmaceutical that induces DNA damage, and olaparib is a PARP inhibitor that interferes with DNA repair mechanisms, we hypothesized their synergy in metastatic castration-resistant prostate cancer (mCRPC). We sought to demonstrate the safety and efficacy of olaparib + radium-223. We conducted a multicenter phase I 3+3 dose escalation study of olaparib with fixed dose radium-223 in patients with mCRPC with bone metastases. The primary objective was to establish the RP2D of olaparib, with secondary objectives of safety, PSA response, alkaline phosphatase response, radiographic progression-free survival (rPFS), overall survival, and efficacy by homologous recombination repair (HRR) gene status. Twelve patients were enrolled; all patients received a prior androgen receptor signaling inhibitor (ARSI; 100%) and 3 patients (25%) prior docetaxel. Dose-limiting toxicities (DLT) included cytopenias, fatigue, and nausea. No DLTs were seen in the observation period however delayed toxicities guided the RP2D. The RP2D of olaparib was 200 mg orally twice daily with radium-223. The most common treatment-related adverse events were fatigue (92%) and anemia (58%). The rPFS at 6 months was 58% (95% confidence interval, 27%-80%). Nine patients were evaluable for HRR gene status; 1 had a BRCA2 alteration (rPFS 11.8 months) and 1 had a CDK12 alteration (rPFS 3.1 months). Olaparib can be safely combined with radium-223 at the RP2D 200 mg orally twice daily with fixed dose radium-223. Early clinical benefit was observed and will be investigated in a phase II study.

ATR Inhibition in Advanced Urothelial Carcinoma

The ataxia telangiectasia and Rad3-related (ATR) checkpoint kinase 1 (CHK1) pathway is intricately involved in protecting the integrity of the human genome by suppressing replication stress and repairing DNA damage. ATR is a promising therapeutic target in cancer cells because its inhibition could lead to an accumulation of damaged DNA preventing further replication and division. ATR inhibition is being studied in multiple types of cancer, including advanced urothelial carcinoma where there remains an unmet need for novel therapies to improve outcomes. Herein, we review preclinical and clinical data evaluating 4 ATR inhibitors as monotherapy or in combination with chemotherapy. The scope of this review is focused on contemporary studies evaluating the application of this novel therapy in advanced urothelial carcinoma.

Phase 2 study (AARDVARC) of AZD4635 in combination with durvalumab and cabazitaxel in patients (pts) with progressive metastatic castrate-resistant prostate cancer (mCRPC)

173

Background: Pts with mCRPC who progress on docetaxel and new hormonal agents (NHAs) have few therapeutic options. In the CARD study of cabazitaxel, 35.7% of pts had PSA responses and 36.5% of pts had tumor responses. While immune checkpoint inhibitors have limited single-agent activity in mCRPC, the combination of the adenosine 2A receptor antagonist, AZD4635, with durvalumab may improve response to chemotherapy. This study assessed AZD4635 in combination with durvalumab (Arm A) or with durvalumab + cabazitaxel (Arm B) in pts with mCRPC. We report interim analysis results from Arm B (Arm A to be reported elsewhere). Methods: Eligible pts had histologically confirmed mCRPC, disease progression ≤6 months prior to enrollment, and were previously treated with docetaxel and 1 NHA. Pts received AZD4635 75 mg PO QD + durvalumab 1500 mg IV Q3W + cabazitaxel Q3W (dosed per locally approved label) for up to 10 cycles. The primary endpoint was radiographic progression-free survival (rPFS), by RECIST v1.1 (soft tissue) or PCWG3 (bone). Secondary endpoints included safety, pharmacokinetics, confirmed PSA50 response, and objective response rate by RECIST v1.1. A futility analysis was planned based on PSA50 responses (confirmed + unconfirmed) after approximately 30 pts were treated. Results: As of August 10, 2021, 28 pts received AZD4635 + durvalumab + cabazitaxel, and 21 pts were still on treatment. Most common adverse events (AEs) possibly related to treatment were nausea (50.0%), diarrhea (46.4%), asthenia, and vomiting (each 28.6%). Treatment-related febrile neutropenia occurred in 7.1% pts. Twelve (42.9%) pts had a serious AE possibly related to treatment. One AE possibly related to treatment led to death (myositis). Exposures of cabazitaxel and/or durvalumab did not change when combined with AZD4635. Median rPFS was 4.4 months (95% CI: 4.2–not calculable) with low percent maturity. Of 28 PSA-evaluable pts, 8 (28.6%) had PSA50 responses (4 confirmed). There were 5 unconfirmed partial responses by RECIST v1.1. Conclusions: Although efficacy data are immature, enrollment was stopped for futility. Safety of the combination was consistent with the known safety profiles of the individual agents. Clinical trial information: NCT04089553 .

Neo-adjuvant PARP inhibition prior to prostatectomy: A phase II biomarker-driven trial for men with high-risk, localized prostate cancer and alterations in DNA repair genes

TPS401

Background: Many men with localized prostate cancer will experience recurrence and progression after radical prostatectomy. While radiation therapy for high-risk prostate cancer is routinely given with systemic androgen therapy, peri-operative systemic therapy is not part of the standard of care with prostatectomy. Defective DNA repair pathways represent a non-hormonal target for PARP inhibitors which have proven efficacy in the metastatic, castrate resistant setting. We designed a novel biomarker driven neoadjuvant trial with niraparib prior to prostatectomy for men with clinically localized high risk prostate cancer and alterations in DNA repair genes (NCT04030559). Methods: We instituted a phase II trial for men with NCCN high and very high-risk prostate cancer. All men who met inclusion by clinical variables underwent targeted genomic sequencing for somatic and/or germline alterations in genes involved in DNA repair pathways. Enrolled patients are treated with oral Niraparib 300mg/day for 90 days before surgery. The primary endpoint is pathologic response at prostatectomy defined as complete response or minimal residual disease (<0.5 cc3) of histological viable cancer. The secondary endpoint is biochemical free survival as well as molecular endpoints including disease responses stratified by mutational status. We have screened 37 men and 10 have met genomic criteria. We have enrolled 8 out of planned 30 men to date, 7 have undergone prostatectomy. Enrolled men have alterations in BRCA2 (germline), MSH6, ZMYM3, MUTYH, ATM, CDK12, ERCC3 and KMT2c. Clinical trial information: NCT04030559 .

EphrinB2 Inhibition and Pembrolizumab in Metastatic Urothelial Carcinoma

PURPOSE

Patients with metastatic urothelial carcinoma have poor prognosis after failure of standard first-line chemotherapy. Immune check point programmed death 1-programmed death ligand 1 antibodies have low response rates and thus there exists a major unmet need.

MATERIALS AND METHODS

In this phase II trial, patients with metastatic urothelial carcinoma that recurred or progressed after platinum-based chemotherapy received soluble EphB4-human serum albumin (sEphB4-HSA) in combination with pembrolizumab. The primary end points were tolerability and overall survival (OS). The secondary end points were progression-free survival (PFS), objective response rate (ORR), duration of response, and toxicity. The expression of sEphB4-HSA target EphrinB2 was correlated with outcomes.

RESULTS

Seventy patients were enrolled. The median follow up was 22.9 months (range, 1.3-54.7). The regimen had acceptable toxicity. In the intent-to-treat analysis (N = 70), the median OS was 14.6 months (95% CI, 9.2 to 21.5). Twenty-six (37%) patients had an objective response (95% CI, 26 to 48). The median PFS was 4.1 (95% CI, 1.5 to 5.7) months. Forty-six (66%) patients expressed EphrinB2, and among them, the median OS was 21.5 months (95% CI, 12.4 to not reached), the ORR was 52% (95% CI, 37 to 67), including a complete response rate of 24% (11 of 46; 95% CI, 12 to 36). The median PFS was 5.7 (95% CI, 2.7 to 27.9) months. Response was maintained at 6, 12, and 24 months in 88%, 74%, and 69% of the patients, respectively.

CONCLUSION

The combination of sEphB4-HSA and pembrolizumab appears synergistic with improved OS and ORR compared with historical data for programmed death 1/programmed death ligand 1 monotherapy.

Total-Body PET Multiparametric Imaging of Cancer Using a Voxelwise Strategy of Compartmental Modeling

Quantitative dynamic PET with compartmental modeling has the potential to enable multiparametric imaging and more accurate quantification than static PET imaging. Conventional methods for parametric imaging commonly use a single kinetic model for all image voxels and neglect the heterogeneity of physiologic models, which can work well for single-organ parametric imaging but may significantly compromise total-body parametric imaging on a scanner with a long axial field of view. In this paper, we evaluate the necessity of voxelwise compartmental modeling strategies, including time delay correction (TDC) and model selection, for total-body multiparametric imaging. Methods: Ten subjects (5 patients with metastatic cancer and 5 healthy volunteers) were scanned on a total-body PET/CT system after injection of 370 MBq of 18F-FDG. Dynamic data were acquired for 60 min. Total-body parametric imaging was performed using 2 approaches. One was the conventional method that uses a single irreversible 2-tissue-compartment model with and without TDC. The second approach selects the best kinetic model from 3 candidate models for individual voxels. The differences between the 2 approaches were evaluated for parametric imaging of microkinetic parameters and the 18F-FDG net influx rate, KiResults: TDC had a nonnegligible effect on kinetic quantification of various organs and lesions. The effect was larger in lesions with a higher blood volume. Parametric imaging of Ki with the standard 2-tissue-compartment model introduced vascular-region artifacts, which were overcome by the voxelwise model selection strategy. Conclusion: The time delay and appropriate kinetic model vary in different organs and lesions. Modeling of the time delay of the blood input function and model selection improved total-body multiparametric imaging.

NCCN Guidelines® Insights: Bladder Cancer, Version 2.2022

The NCCN Guidelines for Bladder Cancer provide recommendations for the diagnosis, evaluation, treatment, and follow-up of patients with bladder cancer and other urinary tract cancers (upper tract tumors, urothelial carcinoma of the prostate, primary carcinoma of the urethra). These NCCN Guidelines Insights summarize the panel discussion behind recent important updates to the guidelines regarding the treatment of non-muscle-invasive bladder cancer, including how to treat in the event of a bacillus Calmette-Guérin (BCG) shortage; new roles for immune checkpoint inhibitors in non-muscle invasive, muscle-invasive, and metastatic bladder cancer; and the addition of antibody-drug conjugates for metastatic bladder cancer.

Bone biomarkers and overall survival (OS) in men with advanced hormone-sensitive prostate cancer (HSPC): Results from SWOG S1216, a phase III trial of ADT +/- orteronel

5071

Background: Circulating bone biomarkers (BB) are strongly prognostic for OS in castration-resistant PC (CRPC). We prospectively evaluated BB in men with HSPC in S1216, a trial that established new OS benchmarks. We sought to identify patient (pt) subsets with differential OS outcomes as defined by BB. Methods: Markers of bone resorption [CTx;PYD] & formation [CICP;BAP] were assessed. Pts were randomly divided into training (1/3) & validation (2/3) sets. In the training set, recursive partitioning of OS was used to identify the ideal dichotomous cutpoint for each BB & for a combination of biomarker split points to define prognostic groups. In the validation set, Cox PH models were used to assess impact of BB on OS, adjusted for pt & tumor characteristics. Adjusted odds ratios for 3-year OS based on BB & baseline clinical factors were developed using logistic regression to estimate receiver operating characteristic (ROC) curves. Results: Of 1,279 men, 949 had baseline BB. Median age–68y; median PSA-28 ng/dL; Gleason>7: 60%; Zubrod PS 0/1-97%. Values of BB at the median & at cutpoints maximized for OS were identified. For 3 of the BB, the cutpoint was at the ̃85th %ile; for PYD it was at the median. Recursive partitioning algorithms applied to the training set identified 4 groups with differential OS based on a dichotomous split of CTx in combination with additional CICP splits within each group. Hazard ratios (HR) for OS based on elevated BBs are shown. ROC analysis showed that only BAP & PYD had significantly higher AUC(0.73;0.74) compared to AUC of baseline clinical factors(0.71) w/ p=0.02 and 0.03 respectively. There was no evidence of BB x treatment interaction (all p>=0.2). Conclusions: In men initiating ADT for HSPC, elevated BB are strongly prognostic for worse OS. BB levels alone & in combination with pt/tumor characteristics identify unique subsets of men with high probability of being alive at 3 years from ADT initiation. These results validate the clinical value of BB in the HSPC state, extending BB utility beyond CRPC. Clinical trial information: NCT01809691. [Table: see text]

A phase I trial of elimusertib in combination with cisplatin or with cisplatin plus gemcitabine in advanced solid tumors with an emphasis on urothelial carcinoma

TPS3174

Background: Cisplatin, a well-established backbone of combination therapy of various advanced solid tumors, inhibits DNA synthesis by forming DNA cross-links and adducts. Despite the activity of cisplatin, tumor cells can either be refractory or develop resistance to treatment. Cisplatin has been demonstrated to cause cell cycle G2/M arrest, which may allow for DNA damage response (DDR) and repair. Ataxia telangiectasia mutated (ATM) and ataxia telangiectasia and Rad 3-related (ATR) protein kinases are key regulators of DDR, and contribute to maintaining genomic integrity in response to various exogenous and endogenous genotoxic insults like cytotoxic chemotherapy. In fact, cisplatin has been shown to transiently increase ATR expression. Inhibitors of ATR have been studied in combination with cisplatin both in vitro and in vivo, demonstrating enhanced activity. The oral small molecule ATR inhibitor elimusertib, which has been studied as a single agent in a Phase I study, has also demonstrated enhanced activity with cisplatin in vitro in lung cancer and bladder cancer cell lines. We sought to conduct a Phase I study evaluating the combination of elimusertib with cisplatin or with cisplatin and gemcitabine. Methods: In the first cohort, patients with histologically confirmed advanced solid tumors for which cisplatin-based therapy would be considered appropriate, who exhibit adequate organ function, and have received < 300 mg/m2 of cisplatin previously are treated with cisplatin on Day (D) 1 and with elimusertib on D2 & 9 of each 21-day cycle. The study follows a phase I queue (IQ) 3+3 dose escalation design, following standard practices for dose-limiting toxicity (DLT) impact on escalation, and when the maximum tolerated dose (MTD) is established with cisplatin alone, this will inform the first dose level of the next cohort, in which patients will be treated with cisplatin on D1, gemcitabine on D1 & 8, and elimusertib on D2 & 9 of each 21-day cycle. An expansion cohort will enroll urothelial carcinoma patients when the second MTD is established. The primary objective of the study is to evaluate the safety and MTD of elimusertib in combination with cisplatin, as well as in combination with cisplatin and gemcitabine. Secondary study objectives include evaluation of pharmacokinetics of elimusertib in these combinations, preliminary efficacy, and evaluating the association between ATM expression and responses to therapy. Currently, 6 patients have been enrolled to the first cohort of the study. Clinical trial information: NCT04491942.

Development of a survey to assess the impact of substance use disorder education on student pharmacists' perspective

INTRODUCTION

The objective of this manuscript is to outline the process involved in the development and validation of a survey that is optimal for assessing the impact of a substance use disorder (SUD) elective course.

METHODS

Face validation was performed once the initial survey was developed. Additionally, field validation was performed by surveying a small population of pharmacy students enrolled in the elective course. Non-parametric chi-square test and factor analysis were performed to analyze survey results and measure survey validity, while Cronbach alpha (CA) was performed to measure reliability.

RESULTS

Student survey responses showed a significance of P < .05 using one sample chi-square test for statements 1, 5, 6, 7, 8, 11, 12, 13, and 15. Factor analysis identified five factors; however, only three factors were identified as having good correlation. Factor 1 related to students' beliefs about patients with SUD, factor 2 related to attitudes about patients with SUD, and factor 3 related to beliefs about SUD. Factors 1, 2, and 3 have a calculated CA > 0.7, indicating strong internal consistency and reliability.

CONCLUSIONS

Some of the original statements loaded as expected and assessed the impact of the course in shaping students' beliefs and attitudes regarding SUD. However, some statements did not load as expected, and the survey was modified in order to better assess the desired endpoints.

Untargeted Metabolomics Identify a Panel of Urinary Biomarkers for the Diagnosis of Urothelial Carcinoma of the Bladder, as Compared to Urolithiasis with or without Urinary Tract Infection in Dogs

Urothelial carcinoma (UC), the most common urologic cancer in dogs, is often diagnosed late because the clinical signs are shared by other non-malignant lower urinary tract disorders (LUTD). The urine-based BRAFV595E test for UC is highly effective only in certain breeds; hence additional non-invasive biomarkers of UC are needed. Here, urine from dogs with UC (n = 27), urolithiasis (n = 8), or urolithiasis with urinary tract infection (UTI) (n = 8) were subjected to untargeted metabolomics analyses, using GC-TOF-MS for primary metabolites, QTOF-MS for complex lipids, and HILIC-QTOF MS for secondary and charged metabolites. After adjusting for age and sex, we identified 1123 known metabolites that were differentially expressed between UC and LUTD. Twenty-seven metabolites were significant (1.5 ≤ log2FC ≤ −1.5, adjusted p-value < 0.05); however, 10 of these could be attributed to treatment-related changes. Of the remaining 17, 6 (hippuric acid, N-Acetylphenylalanine, sarcosine, octanoylcarnitine, N-alpha-methylhistamine, glycerol-3-galactoside) discriminated between UC and LUTD (area under the ROC curve > 0.85). Of the 6 metabolites, only hippuric acid and N-alpha-methylhistamine were discriminatory in both male (n = 20) and female (n = 23) dogs, while sarcosine was an effective discriminator in several breeds, but only in females. Further investigation of these metabolites is warranted for potential use as non-invasive diagnostic biomarkers of dogs with UC that present with LUTD-related clinical signs.

Updated biomarker results from a phase 1/2 study of olaparib and radium-223 in men with metastatic castration-resistant prostate cancer (mCRPC) with bone metastases (COMRADE)

119

Background: Radium-223 is an α-emitting radioisotope that induces DNA double-strand breaks leading to cell death. In preclinical models, PARP inhibitors have shown efficacy as radiosensitizing agents. We designed a phase 1/2 trial to test the safety and efficacy of radium-223 + olaparib. Tissue based studies investigated homologous recombination repair (HRR) gene status. Methods: This was an open-label, multi-center, phase 1/2 study (NCT03317392) evaluating the dosing, safety and efficacy of radium-223 + olaparib. Eligible patients (pts) had mCRPC with ≥2 bone metastases without visceral metastases or lymphadenopathy > 4 cm. There was no limit on prior therapy. All pts had a baseline biopsy and archival tissue was collected when available. The phase 1 used a 3+3 dose escalation design with fixed dose radium-223 (55 kBq/kg IV every 4 weeks x 6). Dose level 1 (DL1) was olaparib 200 mg PO BID; DL2 was olaparib 300 mg PO BID. The primary objective was to determine the recommended phase 2 dose (RP2D). Secondary objectives included radiographic progression-free survival (rPFS) (PCWG3 criteria), PSA response (50% decline from baseline), and alkaline phosphatase response (30% decline from baseline). HRR gene status was determined using Oncopanel tissue profiling. Results: 12 pts were enrolled on the phase 1. Median age was 68 (range 59-81) years. Median prior lines of CRPC therapies was 2 (1-5), including 3 (25%) who had received prior chemotherapy and 12 (100%) a prior novel hormone therapy. The RP2D of olaparib was 200 mg BID when combined with radium-223. Overall, PSA response and alkaline phosphatase response were 16.7% (n=2) and 67% (n=8), respectively. Median follow-up was 6.5 (range 2.8, 11.8) months, and 6-month rPFS was 57% (95% CI: 25%, 80%). 9 patients had available tissue for Oncopanel testing (7 from baseline metastasis biopsy; 2 from archival prostate tissue). Two patients were identified to have pathogenic HRR gene alterations: 1 patient with a BRCA2 mutation with rPFS of 11.63 months, 1 patient with CDK12 mutation with rPFS 2.60 months (Table). Conclusions: We demonstrate that olaparib can be safety combined with radium-223 with RP2D of 200 mg BID. Though limited by sample size, we demonstrate prolonged disease control in a pt with a BRCA2 mutation receiving radium-223 + olaparib. Additional profiling from the currently accruing phase 2 study of radium-223 +/- olaparib will further elucidate biomarkers of response. Clinical trial information: NCT03317392. [Table: see text]

Phase Ib/II trial of Ibrutinib and Nivolumab in Patients with Advanced Refractory Renal Cell Carcinoma1

BACKGROUND: Although immune checkpoint inhibitor-based therapy has improved the outcomes of many patients with metastatic renal cell carcinoma (mRCC), most eventually develop disease progression. Newer agents that modulate immune response can possibly potentiate checkpoint inhibitor therapy. The ITK/ETK/BTK inhibitor ibrutinib has been reported to inhibit myeloid derived suppressor cells in preclinical models and to potentiate immunotherapy. We conducted an investigator-initiated trial of ibrutinib plus the PD1 inhibitor nivolumab in mRCC patients, particularly in those previously exposed to immune checkpoint inhibitors. METHODS: Eligible patients had mRCC of any histologic subtype, completed at least one line of prior systemic therapy which could have included prior immunotherapy, and had acceptable end-organ function with ECOG performance status of 0–2. Treatment consisted of nivolumab 240 mg intravenously every 2 weeks plus ibrutinib 560 mg (dose level 0) or 420 mg (dose level -1) orally once daily. Cycle length was 28 days. Dose limiting toxicity (DLT) was defined as any Grade 3 or higher adverse event (AE) attributable to therapy. After identification of the recommended phase 2 dose (RP2D), up to 19 patients were enrolled to an expansion cohort to further evaluate toxicities and any early evidence of efficacy. The primary endpoints of the trial were establishment of RP2D and progression-free survival (PFS). RESULTS: A total of 31 patients were enrolled, 6 to dose level 0, 7 (of which one was not evaluable for DLT) in dose level -1, and 18 in the expansion cohort. Median age was 60 years (range, 36–90), most had clear cell histology (n = 27; 87%), and most had prior immune checkpoint inhibitor therapy (n = 28; 90%). Three patients experienced one DLT each, all in dose level 0 (all Grade 3), namely elevated lipase, hypoalbuminemia, and nausea. No DLTs were seen in dose level –1 which was declared the RP2D. The most common Grade 3 or higher AEs include anemia (n = 5), lymphocyte count decrease (4), nausea (2), and hypotension (2). Of 28 patients evaluable for response, one patient (3.6%) had a complete response, 2 (7.1%) had a partial response, and 11 (39.2%) had stable disease, for an objective response rate of 10.7%(95%CI: 3.7%–27.2%) and a disease control rate of 50%(95%CI: 32.6%–67.4%). All responders had received prior immune checkpoint inhibitor therapy. Median PFS was 2.5 months (95%CI, 1.9 –4.8) while median OS was 9.1 months (95%CI, 6.6 –19.0). CONCLUSIONS: Ibrutinib at a dose of 420 mg orally once daily in combination with nivolumab 240 mg IV every 2 weeks is feasible and tolerable in mRCC patients. No unique immune-related AEs were observed. Anti-tumor activity was seen in patients previously exposed to PD-1 targeted therapy.

Routine Bone Imaging for Metastatic Renal Cell Carcinoma: Is it Time?

Current guidelines by the National Comprehensive Cancer Network recommend that, in addition to routine computed tomography (CT) imaging, bone imaging and brain magnetic resonance imaging (MRI) should be obtained when clinically indicated. In this issue of the Journal of Kidney Cancer and VHL, a systematic literature review of clinical trials of metastatic renal cell carcinoma (mRCC) patients evaluates the incidence of osseous, lymph node and lung metastases. In particular, the analysis focuses on the changes in incidence over time. The study finds that the incidence of bone, lymph node, and lung metastases has increased over time, and that increases is significant in osseous metastases specifically. These results lead to two provocative questions. First, why have osseous metastases increased in incidence over time? Second, does this finding warrant a more aggressive and uniform approach to imaging to identify osseous metastases sooner?

Effect of Cisplatin and Gemcitabine With or Without Berzosertib in Patients With Advanced Urothelial Carcinoma: A Phase 2 Randomized Clinical Trial

IMPORTANCE

Preclinical studies suggest that inhibition of single-stranded DNA repair by ataxia telangiectasia and Rad3 (ATR) may enhance the cytotoxicity of cisplatin, gemcitabine, and other chemotherapeutic agents. Cisplatin with gemcitabine remains the standard up-front therapy for treatment in patients with metastatic urothelial cancer.

OBJECTIVE

To determine whether the use of the selective ATR inhibitor, berzosertib, could augment the activity of cisplatin with gemcitabine.

DESIGN, SETTING, AND PARTICIPANTS

In a phase 2 randomized clinical trial, 87 patients across 23 centers in the National Cancer Institute Experimental Therapeutics Clinical Trials Network were randomized to receive either cisplatin with gemcitabine alone (control arm) or cisplatin with gemcitabine plus berzosertib (experimental arm). Key eligibility criteria included confirmed metastatic urothelial cancer, no prior cytotoxic therapy for metastatic disease, 12 months or more since perioperative therapy, and eligibility for cisplatin receipt based on standard criteria. The study was conducted from January 27, 2017, to December 15, 2020.

INTERVENTIONS

In the control arm, cisplatin, 70 mg/m2, was given on day 1 and gemcitabine, 1000 mg/m2, was given on days 1 and 8 of a 21-day cycle. In the experimental arm, cisplatin, 60 mg/m2, was given on day 1; gemcitabine, 875 mg/m2, on days 1 and 8; and berzosertib, 90 mg/m2, on days 2 and 9 of a 21-day cycle.

MAIN OUTCOMES AND MEASURES

The primary end point of the study was progression-free survival. The analysis was on all patients who started therapy.

RESULTS

Of the total of 87 patients randomized, 41 patients received cisplatin with gemcitabine alone and 46 received cisplatin with gemcitabine plus berzosertib. Median age was 67 (range, 32-84) years, and 68 patients (78%) were men. Median progression-free survival was 8.0 months for both arms (Bajorin risk-adjusted hazard ratio, 1.22; 95% CI, 0.72-2.08). Median overall survival was shorter with cisplatin with gemcitabine plus berzosertib compared with cisplatin with gemcitabine alone (14.4 vs 19.8 months; Bajorin risk-adjusted hazard ratio, 1.42; 95% CI, 0.76-2.68). Higher rates of grade 3 vs grade 4 thrombocytopenia (59% vs 39%) and neutropenia (37% vs 27%) were observed with cisplatin with gemcitabine and berzosertib compared with cisplatin with gemcitabine alone; consequently, more dose reductions were needed in the experimental arm. Patients in the experimental arm received a median cisplatin dose of 250 mg/m2, which was significantly lower than the median dose of 370 mg/m2 in the control arm (P < .001).

CONCLUSIONS AND RELEVANCE

The addition of berzosertib to cisplatin with gemcitabine did not prolong progression-free survival relative to cisplatin with gemcitabine alone in patients with metastatic urothelial cancer, and a trend toward inferior survival was observed with this combination. Berzosertib plus cisplatin with gemcitabine was associated with significantly higher hematologic toxicities despite attenuated dosing of cisplatin with gemcitabine.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02567409.

Immune Checkpoint Inhibition in Advanced Bladder and Kidney Cancer: Responses and Further Management

Immune checkpoint inhibitors have an established role in the treatment of newly diagnosed metastatic kidney cancer. Treatment regimens combining nivolumab plus ipilimumab, pembrolizumab plus axitinib, nivolumab plus cabozantinib, and pembrolizumab plus lenvatinib have demonstrated superior overall survival compared with sunitinib in randomized studies. Response rates vary from 42% to 71.1% with these combinations. Atezolizumab and pembrolizumab have been approved for the treatment of cisplatin-ineligible patients with metastatic bladder cancer. These and other checkpoint inhibitors have been studied in metastatic bladder cancer and are routinely used after progression on platinum-based chemotherapy. Durable responses are observed in bladder and kidney cancer. Although some patients may experience immune-related adverse events requiring treatment discontinuation, a portion of these patients will continue to experience a response off-therapy. At the time of progression, patients with metastatic kidney cancer may be treated with antiangiogenesis agents, and there are data suggesting that they may also be treated with a rechallenge of immunotherapy. In patients with metastatic bladder cancer who have progression after immune checkpoint inhibition, there are considerable data supporting the use of enfortumab vedotin. Ongoing studies are evaluating novel combinations of immune checkpoint inhibitors with other agents; thus, the treatment landscape of metastatic bladder and kidney cancer is expected to continue to evolve rapidly.

A phase 1/2 study of olaparib and radium-223 in men with metastatic castration-resistant prostate cancer (mCRPC) with bone metastases (COMRADE): Results of the phase 1 study

e17020

Background: Radium-223 is an α-emitting radioisotope that induces DNA double-stranded breaks leading to cell death and has improved survival in mCRPC. In preclinical models, PARP inhibitors have shown efficacy as radiosensitizing agents. We designed a phase 1/2 trial to test the hypothesis that radium-223 + olaparib will demonstrate anti-tumor activity in mCRPC irrespective of homologous recombination repair deficiency (HRD) status. Methods: This is an open label, multi-center, phase 1/2 study (NCT03317392) evaluating the dosing, safety and efficacy of radium-223 + olaparib. Eligible patients (pts) had mCRPC with ≥2 bone metastases without visceral metastases or lymphadenopathy > 4 cm. There was no limit on prior therapy. All pts had a baseline biopsy. The phase 1 used a 3+3 dose escalation design with fixed dose radium-223 (55 kBq/kg IV every 4 weeks x 6). Dose level 1 (DL1) was olaparib 200 mg PO BID; DL2 was olaparib 300 mg PO BID. The primary objective was to determine the recommended phase 2 dose (RP2D) and safety. The dose limiting toxicities (DLT) evaluation period was 2 cycles (1 cycle=28 days). Secondary endpoints included radiographic progression-free survival (rPFS) defined by PCWG3 criteria, PSA response (50% decline from baseline), and alkaline phosphatase response (30% decline from baseline). Results: 12 pts were enrolled on the phase 1. Median age was 68 (range 59-81) years. Median prior lines of CRPC therapies was 2 (1-5), including 3 (25%) who had received prior chemotherapy and 100% a prior novel hormone therapy. 6 pts were enrolled at DL1. 1 patient experienced a DLT outside the DLT evaluation period. 3 pts had grade (G) 3-4 treatment-related adverse events (TrAE) including G3 anemia (n=2) and G3 thrombocytopenia (n=1). No patient underwent dose reductions at DL1. 6 pts were enrolled at DL2. 1 patient experienced a DLT outside the DLT evaluation period. 2 pts had G3-4 TrAE including G3 anemia and G4 lymphocytopenia (n=1) and G3 stroke (n=1). 5 underwent dose reductions at DL2. There were no G5 events. Reason for treatment discontinuation is in the table below. After review of safety data, the safety monitoring committee deemed the RP2D of olaparib at 200 mg BID when combined with radium-223. Overall, PSA response and alkaline phosphatase response were 16.7% (n=2, 1 at DL1, 1 at DL2) and 67% (n=8, 3 at DL1, 5 at DL2), respectively. Median follow-up was 6.5 (range 2.8, 11.8) months, and 6-month rPFS was 57% (95% CI: 25%, 80%). Conclusions: We demonstrate that olaparib can be safety combined with radium-223 with RP2 dose of 200 mg BID. The phase 2 study of radium-223 +/- olaparib is accruing (target 120 pts). Outcomes by HRD status will be presented. Clinical trial information: NCT03317392. [Table: see text]

Association with immune checkpoint inhibitor efficacy of a 27-gene classifier in renal cell cancer

4575

Background: The 27-gene immuno-oncology (IO) signature that incorporates expression from activated inflammatory cells, cancer associated fibroblasts, and tumor cells to produce a binary classifier has been shown to be associated with efficacy to immune checkpoint inhibitors (ICIs) in breast, lung, and bladder cancers. Here we created clustered heat maps using data from The Cancer Genome Atlas (TCGA) to confirm the classifier function and diagnostic threshold in renal cell carcinoma (RCC), then applied the predefined algorithm to RNAseq data from a community RCC cohort treated with ICI therapy. Methods: Previously, we described the selection of 939 genes from the TCGA breast and lung datasets that comprise mesenchymal (M), mesenchymal stem-like (MSL), and immunodulatory (IM) gene expression patterns centered upon the twenty-seven genes selected for the IO score (AACR, 2021). We created an expression dataset using these genes in clear cell (n = 403) and papillary (n = 203) RCC and used k-means clustering to organize the genes and cases (k=3). We assessed the 27-gene classification of cases by utilizing area under the curve for phenotypic classification and determining the sensitivity and specificity of the previously established threshold compared to optimal accuracy for quantitating the fraction of cases enriched into the IM+ cluster (likely sensitive to ICIs) as opposed to the M or MSL clusters (likely insensitive). Finally, the IO score was evaluated in a small multi-institutional RNAseq dataset of forty-three RCC patients treated with an ICI for which there was definitive one-year progression free survival (PFS) data. Results: The 27-gene IO signature applied to the TCGA sample data had an AUC of 90.3 for stratification of cases into IM+ as opposed to M and MSL clusters while the established threshold for likely sensitive enriched 90% of cases into the appropriate IM cluster as opposed 28% into the M and MSL. Efficacy was defined by PFS. Given this result, the 27-gene IO signature was applied with the predefined threshold to the forty-three ICI treated patients. Patients who had a IO+ score by the 27-gene signature had significantly better one-year PFS compared to patients with a negative IO score (hazard ratio = 0.235, 95% CI = 0.069 - 0.803, p < 0.01). Median PFS was 5.2 months for patients classified as IO score negative versus 8.6 months for those classified as IO score+. Conclusions: The 27-gene IO signature has been validated across multiple tumor types and here in RCC to classify the tumor immune microenvironment without changing the algorithm or threshold. Results demonstrate that the 27-gene classifier has a strong correlation with efficacy of ICI therapy in RCC. This is the fourth tumor type in which the same algorithm has been validated as a predictor of ICI efficacy. These data support this assay as a strong pan-cancer immune system classifier worthy of further prospective study for ICI therapy.

A phase 2 study of berzosertib (M6620) in combination with carboplatin compared with docetaxel in combination with carboplatin in metastatic castration-resistant prostate cancer

5034

Background: Alterations in DNA damage repair (DDR) genes are common in metastatic castration-resistant prostate cancer (mCRPC), and are implicated in responses to carboplatin [carbo], PARP inhibitors and immunotherapeutics. Inhibitors of the ATR kinase, which is involved in the DDR response, have been demonstrated to have synergistic activity with platinum compounds in preclinical models. We therefore conducted a phase 2 study of the ATR inhibitor berzosertib [berzo]+carbo vs. docetaxel [doce]+carbo in mCRPC. Methods: Patients (pts) previously treated with at least one secondary hormonal therapy and taxane underwent mandatory pre-treatment biopsy and were randomized 1:1 to receive Arm A (doce 60 mg/m2 day 1 + carbo AUC 4 day 1) or Arm B (berzo 90 mg/m2 days 2,9 + carbo AUC 5 day 1) every 21 days. Pts randomized to Arm A who were not candidates for doce received carbo AUC 5 monotherapy. Stratification factors were 1) prior PARP inhibitor (yes vs. no) and 2) evaluable disease by RECIST 1.1 (yes vs. no). Pts on Arm A crossed over to Arm B (berzo+carbo) at the earlier of PSA or radiographic progression. The primary endpoint was overall response rate (ORR; PSA reduction by ≥ 50% or radiographic response by RECIST 1.1). Secondary endpoints included time to PSA progression, radiographic PFS (rPFS), PFS by PCWG3 criteria, and adverse events (AEs) in each arm. Planned enrollment was 136 pts (for 130 to be treated), with interim analysis for futility after 65 pts were treated. Results: 73 pts were randomized between 6/2019 and 7/2020; 34 pts were treated on Arm A (26 carbo+doce; 8 carbo alone) and 31 on Arm B. Median number of prior systemic therapies (excluding ADT, 5α-reductase inhibitors, 1st generation antiandrogens) was 4 (range 2-8). Median treatment duration was 3 cycles, and 4 pts in each arm discontinued for AEs. Grade 3 or higher treatment-related AEs (TrAE) were seen in 13(38%) pts in Arm A and 21(68%) in Arm B. Pts in Arm B had greater frequency of grade 3-4 thrombocytopenia (8[26%] vs. 3[9%]). 1 pt in Arm B had grade 5 sepsis attributed to study treatment. ORR was 15% in Arm A (5/34; 5/26[19%] in pts who received carbo+doce) and 0% in Arm B (0/31). 14 pts in Arm A crossed over, with no subsequent responses seen. Median rPFS was 2.1(95% CI:2.0,3.2) mo in Arm A and 2.4(1.9,4.2) mo in Arm B. At planned interim analysis, trial enrollment and crossover to Arm B were halted due to futility. Conclusions: Carbo+berzo led to fewer overall responses and a higher rate of grade 3 or higher TrAEs compared to carbo+doce. All responses seen were in pts who received carbo+doce despite requirement for prior progression on taxane, suggesting that this combination is favored over carbo+berzo or carbo monotherapy in a heavily pre-treated biomarker-unselected population. Extensive genetic and molecular studies for DDR assessment from tissue and cfDNA are in progress. Clinical trial information: NCT03517969.

A randomized phase II study comparing cisplatin and gemcitabine with or without berzosertib in patients with advanced urothelial carcinoma

4507

Background: Cisplatin with gemcitabine (CG) remains the standard upfront chemotherapy regimen for metastatic urothelial cancer (mUC). Preclinical synergy was noted between cisplatin and berzosertib, a selective ATR inhibitor. The current study sought to determine if the combination of berzosertib and CG could improve clinical outcomes in mUC. Methods: An open-label, randomized study was conducted across 23 centers in the United States through the Experimental Therapeutics Clinical Trials Network of the National Cancer Institute. Key eligibility criteria included confirmed mUC, no prior cytotoxic therapy for metastatic disease, ≥ 12 months since perioperative therapy and eligibility for cisplatin based on standard criteria. Patients (pts) were randomized to receive either CG alone (control arm) or CG plus berzosertib (experimental arm). In the control arm, 70 mg/m2 of cisplatin was given on day 1 and gemcitabine at 1000 mg/m2 on days 1 and 8 of a 21-day cycle. In the experimental arm, 60 mg/m2 of cisplatin was given on day 1, gemcitabine at 875 mg/m2 on days 1 and 8 and berzosertib at 90 mg/m2 on days 2 and 9 of a 21-day cycle. The primary endpoint of the study was progression-free survival (PFS), with secondary endpoints including response rate (RR), overall survival (OS) and toxicity. Results: A total of 87 pts (median age 67; M:F 68:19) were randomized; 41 pts received CG alone while 46 received CG with berzosertib. Visceral metastases were present in 49% of pts and 52%, 45% and 3% of pts were Bajorin risk 0, 1 and 2, respectively. Median PFS was 8.0 months for both arms (Bajorin risk adjusted hazard ratio [HR] 1.22, 95% confidence interval [CI] 0.72-2.08). RR was 54%(4 CR, 21 PR) in the CG with berzosertib arm and 63% (4 CR, 22 PR) in CG alone arm (P = 0.66). Median OS was shorter with CG with berzosertib as compared to CG alone (14.4 versus 19.8 months; Bajorin risk adjusted HR 1.42, 95%CI 0.76-2.68). Notably higher rates of grade 3/4 thrombocytopenia (59% vs 39%) and neutropenia (37% vs 27%) were observed with CG plus berzosertib compared to CG alone. Higher rates of toxicity-related discontinuation were seen in the experimental arm (24% vs 15%), and the median cumulative cisplatin dose in the experimental arm was 250 mg/m2, as compared to 370 mg/m2 in the control arm (P < 0.001). Conclusions: No improvement in PFS was observed with the addition of berzosertib to CG, and a trend towards inferior survival was observed. These results suggest caution in reducing the starting dose of cytotoxic therapy to accommodate addition of a myelosuppressive agent, as in the experimental arm of this study. Clinical trial information: NCT02567409.

A phase I/II study of combination olaparib and radium-223 in men with metastatic castration-resistant prostate cancer with bone metastases (COMRADE): A trial in progress

TPS182

Background: Radium-223 is an α-emitting radioisotope that induces DNA double-stranded breaks leading to cell death and has demonstrated improvement in overall survival in men with metastatic castration-resistant prostate cancer (mCRPC) with bone metastases. PARP inhibitors, including olaparib and rucaparib, inhibit repair of DNA single-stranded beaks and have demonstrated clinical efficacy in mCRPC patients harboring alterations in the homologous recombination repair (HRR) pathway. In extensive preclinical cancer models, PARP inhibitors have shown efficacy as radiosensitizing agents. We designed a phase 1/2 trial to test the clinical hypothesis that the combination of radium-223 with olaparib will demonstrate anti-tumor activity in patients with mCRPC irrespective of underlying HRR deficiency status. Methods: This is an open label, multi-center, phase 1/2 study (NCT03317392) evaluating the dosing, safety and efficacy of olaparib in combination with radium-223 in men with mCRPC with bone metastases. Patient must have 2 or more bone metastases and at least 1 bone metastasis that has not been treated with prior radiation therapy. Key exclusion criteria include the presence of visceral metastases or malignant lymphadenopathy exceeding 4 cm and prior therapy with radium-223 and/or PARP inhibitors. The phase 1 component of the study uses a 3+3 dose escalation design to determine the recommended phase 2 dose of olaparib in combination with standard of care dosing of Radium-223. The primary endpoint of the phase 1 component is safety. The phase 2 component of the study is an open-label, randomized study evaluating the combination of olaparib and radium-223 compared to radium-223 alone. The primary endpoint of the phase 2 component is radiographic progression-free survival as defined by Prostate Cancer Working Group 3 guidelines for bone metastases and RECIST v1.1 for non-bone metastases. Secondary endpoints include time to PSA progression, PSA response, time to subsequent therapy, time to first skeletal event, overall survival, and safety. Exploratory endpoints include stratification of response based on HRR alterations, whole exome sequencing of plasma cell free DNA both at baseline, on treatment, and at progression, and evaluation of changes in the tumor immune microenvironment with therapy. As of October 1, 2020, the phase 1 component has completed accrual and we anticipate opening the phase 2 component by December 2020. Clinical trial information: NCT03317392.

A phase II study of M6620 in combination with carboplatin compared with docetaxel in combination with carboplatin in metastatic castration-resistant prostate cancer

TPS5597

Background: Alterations in DNA damage repair genes are common in metastatic castration-resistant prostate cancer (mCRPC), and are implicated in responses to carboplatin, PARP inhibitors and immunotherapeutics. The ATR kinase is involved in the DNA damage response, and ATR inhibitors have been demonstrated in preclinical models to have synergistic activity with platinum compounds due to induction of replication stress. Methods: This is a randomized open-label Phase 2 study of the ATR inhibitor M6620 + carboplatin vs. docetaxel + carboplatin in mCRPC. Patients (pts) previously treated with at least one secondary hormonal therapy and taxane-based chemotherapy undergo mandatory pre-treatment biopsy and are randomized 1:1 to receive Arm A (docetaxel 60 mg/m2 day 1 + carboplatin AUC 4 day 1) or Arm B (M6620 90 mg/m2 days 2,9 + carboplatin AUC 5 day 1) every 21 days. Pts randomized to Arm A who are not candidates for docetaxel receive carboplatin AUC 5 monotherapy. Stratification factors are 1) prior PARP inhibitor (yes vs. no) and 2) evaluable disease by RECIST 1.1 (yes vs. no). Pts on Arm A crossover to Arm B (M6620+carboplatin) at the earlier of PSA or radiographic progression. For the primary endpoint of overall response rate (ORR; PSA reduction by ≥ 50% or radiographic response by RECIST 1.1), with 65 pts on each arm (total N = 130), there will be 80% power to distinguish ORR of 40% vs. 20% using a chi-square test (one sided α = 0.05). 136 pts will be enrolled to account for 5% dropout. Secondary endpoints include time to PSA progression, radiographic PFS, PFS by PCWG3 criteria, safety and adverse events in each arm. Biomarker studies include whole exome sequencing, RAD51 focus formation, and ATM IHC from tumor specimens. Circulating cell-free DNA from pre-treatment and progression plasma specimens will undergo ultra-low pass whole genome sequencing and deep targeted sequencing. The goal of this study is to expand therapeutic options in mCRPC through a novel approach to targeting the DNA damage response, and to identify biomarkers associating with response and resistance to both standard and trial therapy. Enrollment began June 2019 (NCI/ETCTN #10191, NCT03517969). Clinical trial information: NCT03517969 .

A phase II study of M6620 in combination with carboplatin compared with docetaxel in combination with carboplatin in metastatic castration-resistant prostate cancer

TPS252

Background: Alterations in DNA damage repair genes are common in metastatic castration-resistant prostate cancer (mCRPC), and are implicated in responses to carboplatin, PARP inhibitors and immunotherapeutics. The ATR kinase is involved in the DNA damage response, and ATR inhibitors have been demonstrated in preclinical models to have synergistic activity with platinum compounds due to induction of replication stress. Methods: This is a randomized open-label Phase 2 study of the ATR inhibitor M6620 + carboplatin vs. docetaxel + carboplatin in mCRPC. Patients (pts) previously treated with at least one secondary hormonal therapy and taxane-based chemotherapy undergo mandatory pre-treatment biopsy and are randomized 1:1 to receive Arm A (docetaxel 60 mg/m2 day 1 + carboplatin AUC 4 day 1) or Arm B (M6620 90 mg/m2 days 2,9 + carboplatin AUC 5 day 1) every 21 days. Pts randomized to Arm A who are not candidates for docetaxel receive carboplatin AUC 5 monotherapy. Stratification factors are 1) prior PARP inhibitor (yes vs. no) and 2) evaluable disease by RECIST 1.1 (yes vs. no). Pts on Arm A crossover to Arm B (M6620+carboplatin) at the earlier of PSA or radiographic progression. For the primary endpoint of overall response rate (ORR; PSA reduction by ≥ 50% or radiographic response by RECIST 1.1), with 65 pts on each arm (total N = 130), there will be 80% power to distinguish ORR of 40% vs. 20% using a chi-square test (one sided α = 0.05). 136 pts will be enrolled to account for 5% dropout. Secondary endpoints include time to PSA progression, radiographic PFS, PFS by PCWG3 criteria, safety and adverse events in each arm. Biomarker studies include whole exome sequencing, RAD51 focus formation, and ATM IHC from tumor specimens. Circulating cell-free DNA from pre-treatment and progression plasma specimens will undergo ultra-low pass whole genome sequencing and deep targeted sequencing. The goal of this study is to expand therapeutic options in mCRPC through a novel approach to targeting the DNA damage response, and to identify biomarkers associating with response and resistance to both standard and trial therapy. Enrollment began June 2019 (NCI/ETCTN #10191). Clinical trial information: NCT03517969.

Immune Checkpoint Inhibitors in the Treatment of Renal Cell Carcinoma

Immune checkpoint inhibitors have quickly become a critical component to the management of advanced renal cell carcinoma. These therapies have been approved for patients who are treatment-naive and who have progressed on antiangiogenesis agents. Combinations of immune checkpoint inhibitors with antiangiogenesis agents show significant response rates and prolong survival. Adverse events associated with the use of checkpoint inhibition present unique challenges in the management of patients, and careful considerations are needed when checkpoint inhibitors are combined with antiangiogenesis agents. Nevertheless, the improvement in overall survival associated with these agents indicates that they will remain a vital component of kidney cancer treatment.