Evaluating Immune Checkpoint Blockade in Metastatic Castration-Resistant Prostate Cancers with Deleterious CDK12 Alterations in the Phase 2 IMPACT Trial.

PURPOSE: CDK12 inactivation in metastatic castration-resistant prostate cancer (mCRPC) may predict immunotherapy responses. This phase 2 trial evaluated the efficacy of immune checkpoint inhibitor (ICI) therapy in patients with CDK12-altered mCRPC. PATIENTS AND METHODS: Eligible patients had mCRPC with deleterious CDK12 alterations and any prior therapies except ICI. Cohort A received ipilimumab (1 mg/kg) with nivolumab (3 mg/kg) every 3 weeks for up to 4 cycles, followed by nivolumab 480 mg every 4 weeks. Cohort C received nivolumab alone 480 mg every 4 weeks. Patients with CDK12-altered non-prostate tumors were enrolled in cohort B and not reported. The primary endpoint was 50% reduction in PSA (PSA50). Key secondary endpoints included PSA progression-free survival (PFS), overall survival (OS), objective response rate (ORR), and safety. RESULTS: PSA was evaluable in 23 patients in cohort A and 14 in cohort C. Median lines of prior therapy were 2 in cohorts A and C, including any prior novel hormonal agent (74% and 79%) and chemotherapy (57% and 36%). The PSA50 rate was 9% (95% CI 1-28%) in cohort A with 2 responders; neither had microsatellite instability or a tumor mutational burden ≥10 mutations/megabase. No PSA50 responses occurred in cohort C. Median PSA-PFS was 7.0 months (95% CI 3.6-11.4) in cohort A and 4.5 months (95% CI 3.4-13.8) in cohort C. Median OS was 9.0 months (95% CI 6.2-12.3) in cohort A and 13.8 months (95% CI 3.6-not reached) in cohort C. CONCLUSIONS: There was minimal activity with ICI therapy in patients with CDK12-altered mCRPC.

Clinical Applications of the Gut Microbiome in Genitourinary Cancers.

Recently recognized as one of the hallmarks of cancer, the microbiome consists of symbiotic microorganisms that play pivotal roles in carcinogenesis, the tumor microenvironment, and responses to therapy. With recent advances in microbiome metagenomic sequencing, a growing body of work has demonstrated that changes in gut microbiome composition are associated with differential responses to immune checkpoint inhibitors (ICIs) because of alterations in cytokine signaling and cytotoxic T-cell recruitment. Therefore, strategies to shape the gut microbiome into a more favorable, immunogenic profile may lead to improved responses with ICIs. Immunotherapy is commonly used in genitourinary (GU) cancers such as renal cell carcinoma, urothelial cancer, and to a limited extent, prostate cancer. However, a subset of patients do not derive clinical benefit with ICIs. Gut microbiome-based interventions are of particular interest given the potential to boost responses to ICIs in preclinical and early-phase prospective studies. Novel approaches using probiotic therapy (live bacterial supplementation) and fecal microbiota transplantation in patients with GU cancers are currently under investigation.

Novel Approaches with HIF-2α Targeted Therapies in Metastatic Renal Cell Carcinoma.

Germline inactivation of the Von Hippel-Lindau (VHL) tumor suppressor is the defining hallmark in hereditary VHL disease and VHL-associated renal cell carcinoma (RCC). However, somatic VHL mutations are also observed in patients with sporadic RCC. Loss of function VHL mutations result in constitutive activation of hypoxia-inducible factor-2 alpha (HIF-2α), which leads to increased expression of HIF target genes that promote angiogenesis and tumor growth. As of 2023, belzutifan is currently the only approved HIF-2α inhibitor for both VHL-associated and sporadic metastatic RCC (mRCC). However, there is potential for resistance with HIF-2α inhibitors which warrants novel HIF-2α-targeting strategies. In this review, we discuss the potential resistance mechanisms with belzutifan and current clinical trials evaluating novel combinations of belzutifan with other targeted therapies and immune checkpoint inhibitors which may enhance the efficacy of HIF-2α targeting. Lastly, we also discuss newer generation HIF-2α inhibitors that are currently under early investigation and outline future directions and challenges with HIF-2α inhibitors for mRCC.

Determinants of Bone-Modifying Agent Prescribing for Metastatic Castration-Resistant Prostate Cancer in a National Health Care Delivery System.

PURPOSE: Despite guidelines recommending bone-modifying agents (BMAs) to decrease skeletal-related events (SREs) in men with metastatic castration-resistant prostate cancer (mCRPC), BMAs are underutilized. In this retrospective cohort study, we report the factors associated with BMA use in a national health care delivery system. METHODS: We used the Veterans Affairs Corporate Data Warehouse to identify men with mCRPC between 2010 and 2017. BMA prescribing frequency was evaluated, and the association between patient- and disease-specific factors with BMA use was assessed using multivariable logistic regression. RESULTS: Among 3,980 men identified with mCRPC (mean age 73.5 years, 29% Black), 47% received a BMA; median time to BMA from start of mCRPC treatment was 102 days. Factors associated with BMA use included previous BMA use (adjusted odds ratio [aOR], 7.81 [95% CI, 6.48 to 9.47]), diagnosis code for bone metastases (aOR, 1.26 [95% CI, 1.08 to 1.46]), and concomitant corticosteroid use (aOR, 1.53 [95% CI, 1.29 to 1.82]). Decreased BMA use was associated with advancing age (aOR, 0.85 per 10 years [95% CI, 0.78 to 0.92]), Charlson comorbidity index ≥2 (aOR, 0.76 [95% CI, 0.63 to 0.93]), Black race (aOR, 0.83 [95% CI, 0.70 to 0.98]), and decreased estimated glomerular filtration rate (eGFR; aOR, 0.19 [95% CI, 0.11 to 0.32] for eGFR 0-29 mL/minutes; aOR, 0.76 [95% CI, 0.64 to 0.91] for 30-59 mL/minutes). CONCLUSION: Patients who are older, Black, or have more comorbidities are less likely to receive guideline concordant care to prevent SREs. These observations highlight the unique challenges of caring for patients with mCRPC and the need for future studies to increase BMA use in these populations.

Pathogenic Germline Mutational Landscape in Patients With Renal Cell Carcinoma and Associated Clinicopathologic Features.

PURPOSE: A subset of renal cell carcinoma (RCC) cases occur because of a hereditary predisposition. However, the prevalence and profiling of germline alterations in RCC have not been fully characterized. Additionally, clinicopathologic factors associated with pathogenic or likely pathogenic (P/LP) germline variants in patients with RCC remain poorly understood. METHODS: A retrospective analysis of patients with RCC who underwent genetic evaluation was performed. The frequency of P/LP germline variants and genes was evaluated in this cohort. The association between genetic testing outcomes and clinicopathologic features was also assessed. RESULTS: A total of 321 patients with RCC who had germline testing were identified. Within this cohort, 42 patients (13.1%) had P/LP variants. Genes with the most frequent germline mutations were FLCN (n = 10, 3.1%), SDHB (n = 4, 1.2%), VHL (n = 4, 1.2%), MLH1 (n = 3, 0.9%), and CHEK2 (n = 4, 1.2%). Among patients with P/LP variants, 19 (45.2%) had a potentially targetable mutation. The presence of bilateral or multifocal tumors was associated with P/LP variants (P = .0012 and P = .0098, respectively). Patients who had targeted gene testing had higher rates of P/LP variants compared with multigene panel testing (P = .015). Age and family history of cancers (RCC and non-RCC) did not have any statistically significant association with germline testing outcomes. CONCLUSION: Among patients with RCC, unselected for a known familial predisposition, 13.4% had P/LP variants. Almost half of patients with P/LP variants had a potentially targetable mutation. Targeted gene panel testing is a feasible option for patients, particularly if syndromic features are present. Age and family history were not associated with P/LP variants. Future studies are needed to optimize current genetic evaluation criteria to expand the detection of patients with RCC who may have germline mutations.

A Phase 2 Trial of Nab-paclitaxel in Combination With Anti-PD1 Therapy in Advanced Urothelial Cancer.

PURPOSE: Immune checkpoint inhibitor therapy and nab-paclitaxel have each shown efficacy in platinum-refractory advanced urothelial cancer. We conducted a single-arm phase 2 trial of the combination of nab-paclitaxel and pembrolizumab in platinum-refractory or cisplatin-ineligible advanced urothelial cancer (NCT03240016). MATERIALS AND METHODS: Eligible patients had RECIST 1.1 measurable and cisplatin-ineligible or platinum-refractory advanced urothelial cancer. Patients received nab-paclitaxel at starting dose of 125 mg/m2 intravenously on days 1 and 8 and pembrolizumab 200 mg intravenously on day 1 in 21-day cycles until progression, intolerable toxicity, or death. Nab-paclitaxel was permitted to be discontinued after 6 cycles. The nab-paclitaxel starting dose was reduced to 100 mg/m2 after planned interim analysis. Primary end point was overall response rate by RECIST 1.1. Secondary end points included safety/toxicity, duration of response, progression-free survival), and overall survival. RESULTS: Between February 2018 and April 2021, 36 response-evaluable patients were enrolled. There was an equal split of platinum-refractory and cisplatin-ineligible patients. Confirmed overall response rate was 50.0% (18/36) including 3 complete and 15 partial responses; 31/36 patients experienced some tumor shrinkage. At a median follow-up of 19.7 months, median duration of response was 4.4 months (95% CI: 4.0-8.6), median progression-free survival 6.8 months (95% CI: 4.4-not reached), and median overall survival 18.2 months (95% CI: 10.6-not reached). Grade ≥3 adverse events occurred in 21/36 patients including fatigue (n=6) and anemia (n=4). Ten patients had immune-mediated adverse events. CONCLUSIONS: The combination of nab-paclitaxel and pembrolizumab exhibited promising activity in advanced urothelial cancer and warrants further study in this population. After reduction in nab-paclitaxel starting dose, no unanticipated or unexpected toxicities emerged.

Case report: Immune-mediated meibomian gland dysfunction following pembrolizumab therapy for advanced urothelial carcinoma.

Ocular immune-related adverse events are a relatively rare complication of immune checkpoint inhibitors. Common ocular toxicities range from dry eyes to inflammatory uveitis and ocular myasthenia gravis. Here, we present the case of a 55-year-old woman with recurrent urothelial carcinoma of the ureter after initially being managed with neoadjuvant cisplatin-based chemotherapy and surgical resection. She was treated with pembrolizumab which was complicated by immune-mediated pneumonitis after the eighth cycle, which was managed with a prolonged steroid course. The patient also developed red eyes along with recurrent styes. Eye examination revealed decreased tear breakup time, expression of thick and turbid meibum, and meibomian gland atrophy on infrared meibography. The patient was diagnosed with suspected immune-mediated meibomian gland dysfunction (MGD) as a result of pembrolizumab, a previously unreported complication of immunotherapy. The goal of MGD therapy is to stabilize the tear film and minimize evaporation with lipid-based lubricants and other conservative treatments.

Primary bone lymphoma of the ilium successfully treated without radiation.

The addition of radiation therapy to chemotherapy and impact on outcomes in primary bone lymphoma is not clear. Nonetheless, tumor location must be considered as radiation to marrow-rich bone areas can lead to myelosuppression and myelotoxicity.

Doublecortin-like kinase 1 promotes hepatocyte clonogenicity and oncogenic programming via non-canonical ß-catenin-dependent mechanism.

Chronic liver injury is a risk factor for cirrhosis and hepatocellular carcinoma (HCC). The molecular mechanisms that regulate the decision between normal injury repair and neoplastic initiation are unclear. Doublecortin-like kinase 1 (DCLK1), a tumor stem cell marker, is induced during cirrhosis and HCC. Here, we demonstrate that DCLK1-overexpressing primary human hepatocytes formed spheroids in suspension cultures. Spheroids derived from DCLK1-overexpressing hepatoma cells showed high level expression of active ß-catenin, α-fetoprotein, and SOX9, suggesting that DCLK1 overexpression induces clonogenicity and dedifferentiated phenotypes in hepatoma cells. DCLK1 overexpression in hepatoma cells also increased phosphorylation of GSK-3ß at Ser9. This was associated with an induction of a 48-kDa active ß-catenin with a preserved hypophosphorylated N-terminus that interacted with nuclear TCF-4 resulting in luciferase reporter activity and cyclin D1 expression. DCLK1 downregulation inhibited 48-kDa ß-catenin expression. The proteasome inhibitor bortezomib did not block the 48-kDa ß-catenin, instead, caused a threefold accumulation, suggesting a proteasome-independent mechanism. Liver tissues from patients with cirrhosis and HCC revealed epithelial co-staining of DCLK1 and active ß-catenin, and cleaved E-cadherin. Repopulated DCLK1-overexpressing primary human hepatocytes in humanized FRG mouse livers demonstrated active ß-catenin. In conclusion, DCLK1 regulates oncogenic signaling and clonogenicity of hepatocytes by a novel non-canonical/atypical ß-catenin-dependent mechanism.

APSA Awardee Submission: Tumor/cancer stem cell marker doublecortin-like kinase 1 in liver diseases.

Liver diseases are the fourth leading cause of mortality among adults in the United States. Patients with chronic liver diseases such as viral hepatitis, fibrosis, and cirrhosis have significantly higher risks of developing hepatocellular carcinoma (HCC). With a dismal five-year survival rate of 11%, HCC is the third most common cause of cancer-related deaths worldwide. Regardless of the underlying cause, late presentation and a lack of effective therapy are the major impediments for successful treatment of HCC. Therefore, there is a considerable interest in developing new strategies for the prevention and treatment of chronic liver diseases at the early stages. Cancer stem cells (CSCs), a small cell subpopulation in a tumor, exhibit unlimited self-renewal and differentiation capacity. These cells are believed to play pivotal roles in the initiation, growth, metastasis, and drug-resistance of tumors. In this review, we will briefly discuss pivotal roles of the CSC marker doublecortin-like kinase 1 (DCLK1) in hepatic tumorigenesis. Recent evidence suggests that anti-DCLK1 strategies hold promising clinical potential for the treatment of cancers of the liver, pancreas, and colon.

(Z)-3,5,4'-Trimethoxystilbene Limits Hepatitis C and Cancer Pathophysiology by Blocking Microtubule Dynamics and Cell-Cycle Progression.

Hepatocellular carcinoma (HCC) is the third most common cause of cancer-related deaths worldwide. Chronic hepatitis C virus (HCV) infection causes induction of several tumors/cancer stem cell (CSC) markers and is known to be a major risk factor for development of HCC. Therefore, drugs that simultaneously target viral replication and CSC properties are needed for a risk-free treatment of advanced stage liver diseases, including HCC. Here, we demonstrated that (Z)-3,5,4'-trimethoxystilbene (Z-TMS) exhibits potent antitumor and anti-HCV activities without exhibiting cytotoxicity to human hepatocytes in vitro or in mice livers. Diethylnitrosamine (DEN)/carbon tetrachloride (CCl4) extensively induced expression of DCLK1 (a CSC marker) in the livers of C57BL/6 mice following hepatic injury. Z-TMS exhibited hepatoprotective effects against DEN/CCl4-induced injury by reducing DCLK1 expression and improving histologic outcomes. The drug caused bundling of DCLK1 with microtubules and blocked cell-cycle progression at G2-M phase in hepatoma cells via downregulation of CDK1, induction of p21(cip1/waf1) expression, and inhibition of Akt (Ser(473)) phosphorylation. Z-TMS also inhibited proliferation of erlotinib-resistant lung adenocarcinoma cells (H1975) bearing the T790M EGFR mutation, most likely by promoting autophagy and nuclear fragmentation. In conclusion, Z-TMS appears to be a unique therapeutic agent targeting HCV and concurrently eliminating cells with neoplastic potential during chronic liver diseases, including HCC. It may also be a valuable drug for targeting drug-resistant carcinomas and cancers of the lungs, pancreas, colon, and intestine, in which DCLK1 is involved in tumorigenesis. Cancer Res; 76(16); 4887-96. ©2016 AACR.

Inflammatory and oncogenic roles of a tumor stem cell marker doublecortin-like kinase (DCLK1) in virus-induced chronic liver diseases.

Hepatocellular carcinoma (HCC) is the third most common cause of cancer-related mortality worldwide. We previously showed that a tumor/cancer stem cell (CSC) marker, doublecortin-like kinase (DCLK1) positively regulates hepatitis C virus (HCV) replication, and promotes tumor growth in colon and pancreas. Here, we employed transcriptome analysis, RNA interference, tumor xenografts, patient's liver tissues and hepatospheroids to investigate DCLK1-regulated inflammation and tumorigenesis in the liver. Our studies unveiled novel DCLK1-controlled feed-forward signaling cascades involving calprotectin subunit S100A9 and NFκB activation as a driver of inflammation. Validation of transcriptome data suggests that DCLK1 co-expression with HCV induces BRM/SMARCA2 of SW1/SNF1 chromatin remodeling complexes. Frequently observed lymphoid aggregates including hepatic epithelial and stromal cells of internodular septa extensively express DCLK1 and S100A9. The DCLK1 overexpression also correlates with increased levels of S100A9, c-Myc, and BRM levels in HCV/HBV-positive patients with cirrhosis and HCC. DCLK1 silencing inhibits S100A9 expression and hepatoma cell migration. Normal human hepatocytes (NHH)-derived spheroids exhibit CSC properties. These results provide new insights into the molecular mechanism of the hepatitis B/C-virus induced liver inflammation and tumorigenesis via DCLK1-controlled networks. Thus, DCLK1 appears to be a novel therapeutic target for the treatment of inflammatory diseases and HCC.