Cabozantinib in Chemotherapy-Pretreated Metastatic Castration-Resistant Prostate Cancer: Results of a Phase II Nonrandomized Expansion Study

Cabozantinib (XL184), an oral inhibitor of multiple receptor tyrosine kinases such as MET and VEGFR2, was evaluated in a phase II nonrandomized expansion study in castration-resistant prostate cancer (CRPC)

Cabozantinib in Patients With Advanced Prostate Cancer: Results of a Phase II Randomized Discontinuation Trial

PurposeCabozantinib (XL184) is an orally bioavailable tyrosine kinase inhibitor with activity against MET and vascular endothelial growth factor receptor 2. We evaluated the activity of cabozantinib in patients with castration-resistant prostate cancer (CRPC) in a phase II randomized discontinuation trial with an expansion cohort.Patients and methodsPatients received 100 mg of cabozantinib daily. Those with stable disease per RECIST at 12 weeks were randomly assigned to cabozantinib or placebo. Primary end points were objective response rate at 12 weeks and progression-free survival (PFS) after random assignment.ResultsOne hundred seventy-one men with CRPC were enrolled. Random assignment was halted early based on the observed activity of cabozantinib. Seventy-two percent of patients had regression in soft tissue lesions, whereas 68% of evaluable patients had improvement on bone scan, including complete resolution in 12%. The objective response rate at 12 weeks was 5%, with stable disease in 75% of patients. Thirty-one patients with stable disease at week 12 were randomly assigned. Median PFS was 23.9 weeks (95% CI, 10.7 to 62.4 weeks) with cabozantinib and 5.9 weeks (95% CI, 5.4 to 6.6 weeks) with placebo (hazard ratio, 0.12; P < .001). Serum total alkaline phosphatase and plasma cross-linked C-terminal telopeptide of type I collagen were reduced by ≥ 50% in 57% of evaluable patients. On retrospective review, bone pain improved in 67% of evaluable patients, with a decrease in narcotic use in 56%. The most common grade 3 adverse events were fatigue (16%), hypertension (12%), and hand-foot syndrome (8%).ConclusionCabozantinib has clinical activity in men with CRPC, including reduction of soft tissue lesions, improvement in PFS, resolution of bone scans, and reductions in bone turnover markers, pain, and narcotic use

Income inequality and treatment of African American men with high-risk prostate cancer

Definitive treatment of high-risk prostate cancer with radical prostatectomy or radiation improves survival. We assessed whether racial disparities in the receipt of definitive therapy for prostate cancer vary by regional income. A cohort of 102,486 men (17,594 African American [AA] and 84,892 non-Hispanic white) with localized high-risk prostate cancer (prostate-specific antigen >20ng/ml or Gleason≥8 or stage≥cT2c) diagnosed from 2004 to 2010 was identified in the Surveillance, Epidemiology, and End Results database. Income was measured at the census-tract-level. We used multivariable logistic regression to assess patient and cancer characteristics associated with the receipt of definitive therapy for prostate cancer. Multivariable Fine and Gray competing risks analysis was used to evaluate factors associated with prostate cancer death. Overall, AA men were less likely to receive definitive therapy than white men (adjusted odds ratio [AOR] = 0.51; 95% CI: 0.49–0.54; P<0.001), and there was a significant race/income interaction (Pinteraction = 0.016) such that there was a larger racial treatment disparity in the bottom income quintile (AOR = 0.49; 95% CI: 0.45–0.55; P<0.001) than in the top income quintile (AOR = 0.60; 95% CI: 0.51–0.71; P<0.001). After a median follow-up of 35 months, AA men in the bottom income quintile suffered the greatest prostate cancer mortality (adjusted hazard ratio = 1.47; 95% CI: 1.17–1.84; P = 0.001), compared with white men in the top income quintile. Racial disparities in the receipt of definitive therapy for high-risk prostate cancer are greatest in low-income communities, suggesting that interventions to reduce racial disparities should target low-income populations first