Summary of PK data for EZH2 inhibitors used in KARPAS-422 and HT1376 xeograft mmouse models

Tulmimetostat increases PRC2-repressed gene expression in ARID1A mutant bladder cancer cells. (

In cancer patients tulmimetostat plasma exposure levels correlate with PRC2 target gene expression changes in peripheral blood.

Table with cell line information including source and RRID

List of 365 genes (used in main Fig. 7F) that are induced in patient’s whole blood upon treatment with tulmimetostat

Tulmimetostat treatment results in greater PRC2 target gene expression induction in phenotypically sensitive ARID1A LOF cell lines

List of gene names corresponding to 132 tulmimetostat upregulated genes in responder versus non responder cell lines

Tulmimetostat mediated cancer cell phenotypic responses are increased in ARID1A LOF contexts.

Tulmimetostat improves cisplatin responsiveness in chemotherapy-resistant bladder cancer cells.

Synthetic pathway and characterization of tulmimetostat, a long residence time EZH2 inhibitor.

Tulmimetostat demonstrates superior level of tumor PRC2 target gene inducon and correlation with efficacy in a bladder cancer xenograft mouse model.

Table listing experimentally determined compound binding affinities for EZH2 and EZH1 containing PRC2 protein complexes

Additional method information to describe technical aspects of the experiments described in this manuscript

Renin-angiotensin-aldosterone system inhibitors (RAASI) have been shown to improve outcomes in various malignancies. In this retrospective, single-center study, we found that concurrent use of RAASI in patients with mRCC receiving IO is associated with a significantly increased likelihood of tumor regression. Our findings suggest the potential therapeutic advantage of RAASI in combination with IO for mRCC patients. Background: The renin-angiotensin-aldosterone system (RAAS), traditionally associated with blood pressure and fluid regulation, also plays a role in tumorigenesis. Renin-angiotensin-aldosterone system inhibitors (RAASI), including angiotensin converting enzyme inhibitors (ACEI) and angiotensin receptor blockers (ARBs), have been shown to improve outcomes in various malignant neoplasms. In metastatic urothelial cancer, the use of RAASI have been associated with higher rates of tumor regression in patients receiving immunotherapy (IO) with PD1/L1 inhibitors. This is thought to be due to RAASI-induced downregulation of TGF-beta, for which increased expression is a known mechanism of PD1/L1 inhibitor resistance. We hypothesized that concurrent RAASI in patients with mRCC receiving IO is associated with increased tumor regression. Methods: We conducted a retrospective analysis of patients with mRCC receiving IO as a first- or second-line therapy from 2016-2023 at the University of Virginia. A logistic regression model was used to evaluate the impact of concurrent RAASI on tumor regression. The primary endpoint was any regression of tumor on imaging. Results: Data were available for 128 patients with mRCC who received IO as a first- (n = 91, 71.0%) or second- (n = 37, 28.9%) line treatment. Patients who received RAASI during IO were more likely to have tumor regression compared to patients who were not on concurrent RAASI (OR 3.84 [95% CI 1.81-8.47, P = < .001). This held true regardless if patients received IO as a first-line (OR 2.83 [95% CI 1.2-6.94], P = .0173) or second-line (OR 9.5 [95% CI 1.89-73.1], P = .005) treatment. Conclusions: Our hypothesis generating study suggests that in our mRCC population, concurrent use of RAASI in patients receiving IO was associated with a significantly increased likelihood of tumor regression. These findings highlight the potential therapeutic advantage of RAASI in combination with IO for mRCC patients. Further exploration of this association is warranted in prospective studies to improve treatment outcomes for this patient population.

Most men with newly appreciated metastatic prostate cancer are optimally treated with a backbone consisting of androgen receptor-directed therapy with or without taxane chemotherapy. Despite improvements in disease outcomes, prostate cancer remains an extremely heterogeneous disease with variable mechanisms of therapeutic resistance. As a result, it remains a leading cause of cancer-related death in men. Radiopharmaceutical therapy has emerged as an alternative, non-androgen receptor-directed treatment modality for metastatic castration-resistant prostate cancer that impacts patient survival and represents a potentially more personalized approach. In this review, we aim to outline the current treatment landscape for metastatic prostate cancer with a focus on radiopharmaceutical therapy, specifically 177Lu-PSMA-617. In addition, we illustrate various clinical challenges with 177Lu-PSMA-617 treatment to date and explore investigative efforts to leverage radiopharmaceutical therapies as part of combination regimens or earlier in the treatment algorithm to further improve patient outcomes. Finally, we introduce ongoing studies of alternative radiopharmaceutical therapies in metastatic prostate cancer that may be incorporated into the treatment algorithm pending further study.

Recurrent somatic mutations in the BRG1/BRM-associated factor (BAF) chromatin remodeling complex subunit ARID1A occur frequently in advanced urothelial, endometrial, and ovarian clear cell carcinomas, creating an alternative chromatin state that may be exploited therapeutically. The histone methyltransferase EZH2 has been previously identified as targetable vulnerability in the context of ARID1A mutations. In this study, we describe the discovery of tulmimetostat, an orally available, clinical stage EZH2 inhibitor, and it elucidates the aspects of its application potential in ARID1A mutant tumors. Tulmimetostat administration achieved efficacy in multiple ARID1A mutant bladder, ovarian, and endometrial tumor models and improved cisplatin response in chemotherapy-resistant models. Consistent with its comprehensive and durable level of target coverage, tulmimetostat demonstrated greater efficacy than other PRC2-targeted inhibitors at comparable or lower exposures in a bladder cancer xenograft mouse model. Tulmimetostat mediated extensive changes in gene expression, in addition to a profound reduction in global H3K27me3 levels in tumors. Phase I clinical pharmacokinetic and pharmacodynamic data indicated that tulmimetostat exhibits durable exposure and profound target engagement. Importantly, a tulmimetostat controlled gene expression signature identified in whole blood from a cohort of 32 patients with cancer correlated with tulmimetostat exposure, representing a pharmacodynamic marker for the assessment of target coverage for PRC2-targeted agents in the clinic. Collectively, these data suggest that tulmimetostat has the potential to achieve clinical benefit in solid tumors as a monotherapy but also in combination with chemotherapeutic agents, and may be beneficial in various indications with recurrent ARID1A mutations. Significance: The EZH2 inhibitor tulmimetostat achieves comprehensive target inhibition in ARID1A mutant solid tumor models and cancer patients that can be assessed with a pharmacodynamic gene signature in peripheral blood.

A 69-year-old male presented with 4 weeks of left lower quadrant abdominal with associated shortness of breath and 15 pounds of weight loss. History is significant for psoriatic arthritis, coronary artery disease s/p coronary artery bypass graft and 6 cardiac stents, mitral regurgitation, and bicuspid aortic valve. He is a former smoker and family history is significant for renal cell carcinoma in his mother. His Eastern Cooperative Oncology Group (ECOG) performance status was 1. Laboratory blood workup showed creatinine 1.4 mg/dL (normal range: 0.7-1.3 mg/dL) and LDH 716 U/L (normal range: 125-250 U/L). The remaining laboratory values were unremarkable. CT abdomen and pelvis demonstrated a large heterogeneous mass in the left retroperitoneum involving the kidney, perinephric space, adrenal gland, psoas muscle, and invasion through Gerota's fascia anteriorly. Encasement and narrowing of the left renal vein and artery by the mass was also noted. CT chest showed bilateral solid and ground glass pulmonary nodules suspicious for metastatic disease (Fig. 1 A-D, Supplementary Figure 1).

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.

Background Immune checkpoint inhibitors (ICI) improve overall survival (OS) in patients with locally advanced, unresectable, or metastatic urothelial carcinoma (aUC), but response rates can be modest. We compared outcomes between patients with and without prior intravesical Bacillus Calmette-Guerin (BCG), who received ICI for aUC, hypothesizing that prior intravesical BCG would be associated with worse outcomes. Patients and Methods We performed a retrospective cohort study across 25 institutions in US and Europe. We compared observed response rate (ORR) using logistic regression; progression-free survival (PFS) and OS using Kaplan-Meier and Cox proportional hazards. Analyses were stratified by treatment line (first line/salvage) and included multivariable models adjusting for known prognostic factors. Results A total of 1026 patients with aUC were identified; 614, 617, and 638 were included in ORR, OS, PFS analyses, respectively. Overall, 150 pts had history of prior intravesical BCG treatment. ORR to ICI was similar between those with and without prior intravesical BCG exposure in both first line and salvage settings (adjusted odds radios 0.55 [P= .08] and 1.65 [P= .12]). OS (adjusted hazard ratios 1.05 [P= .79] and 1.13 [P= .49]) and PFS (adjusted hazard ratios 1.12 [P= .55] and 0.87 [P= .39]) were similar between those with and without intravesical BCG exposure in first line and salvage settings. Conclusion Prior intravesical BCG was not associated with differences in response and survival in patients with aUC treated with ICI. Limitations include retrospective nature, lack of randomization, presence of selection and confounding biases. This study provides important preliminary data that prior intravesical BCG exposure may not impact ICI efficacy in aUC.