Sartor, Oliver

AbstractBackgroundProstate‐specific membrane antigen (PSMA) is a well‐established therapeutic and diagnostic target overexpressed in both primary and metastatic prostate cancers. PSMA antibody‐drug conjugate (PSMA ADC) is a fully human immunoglobulin G1 anti‐PSMA monoclonal antibody conjugated to monomethylauristatin E, which binds to PSMA‐positive cells and induces cytotoxicity. In a phase 1 study, PSMA ADC was well tolerated and demonstrated activity as measured by reductions in serum prostate‐specific antigen (PSA) and circulating tumor cells (CTCs). To further assess PSMA ADC, we conducted a phase 2 trial in metastatic castration‐resistant prostate cancer (mCRPC) subjects who progressed following abiraterone/enzalutamide (abi/enz) therapy.MethodsA total of 119 (84 chemotherapy‐experienced and 35 chemotherapy‐naïve) subjects were administered PSMA ADC 2.5 or 2.3 mg/kg IV q3w for up to eight cycles. Antitumor activity (best percentage declines in PSA and CTCs from baseline and tumor responses through radiological imaging), exploratory biomarkers, and safety (monitoring of adverse events [AEs], clinical laboratory tests, and Eastern Cooperative Oncology Group performance status) were assessed.ResultsPSA declines ≥50% occurred in 14% of all treated (n = 113) and 21% of chemotherapy‐naïve subjects (n = 34). CTC declines ≥50% were seen in 78% of all treated (n = 77; number of subjects with ≥5 CTCs at baseline and a posttreatment result) and 89% of chemotherapy‐naïve subjects (n = 19); 47% of all treated and 53% of chemotherapy‐naïve subjects had a transition from ≥5 to less than 5 CTCs/7.5 mL blood at some point during the study. PSA and CTC reductions were associated with high PSMA expression (CTCs or tumor tissue) and low neuroendocrine serum markers. In the chemotherapy‐experienced group, the best overall radiologic response to PSMA ADC treatment was stable disease in 51 (60.7%) subjects; 5.7% of subjects in the chemotherapy‐naïve group had partial responses. The most common treatment‐related AEs ≥Common Terminology Criteria for AE (CTCAE) grade 3 were neutropenia, fatigue, electrolyte imbalance, anemia, and neuropathy. The most common serious AEs were dehydration, hyponatremia, febrile neutropenia, and constipation. Two subjects who received 2.5 mg/kg died of sepsis.ConclusionsPSMA ADC demonstrated some activity with respect to PSA declines, CTC conversions/reductions, and radiologic assessments in abi/enz treated mCRPC subjects. Clinically significant treatment‐related AEs included neutropenia and neuropathy.

3 Background: Previous reports suggested that AAT when combined with salvage RT following RP in patients may improve prostate cancer control outcomes. Methods: Post-RP patients with pT3pN0 or with pT2pN0 and positive margins who had or developed elevated PSA levels from 0.2 to 4.0 ng/ml were randomized on a phase III, double-blind, trial of RT + placebo (64.8 Gy in 36 fractions of 1.8 Gy) vs. RT + AAT (24 months bicalutamide, 150 mg daily) during and after RT. The primary end-point was overall survival. Trial design required 725 patients and provided 80% power to detect a reduction in death rate by at least 28.5% and a 1-sided significance level of 0.046. Results: From 3/98 to 3/03, 761 eligible patients (median age 65) were randomized to RT + AAT (384) or RT + placebo (377). 248 patients (33%) were pT2pN0 and 513 (67%) were pT3pN0. 671 (88%) had a PSA nadir after RP of < 0.5 ng/ml. 649 (85%) had an entry PSA value of <1.6, 112 patients (15%) had an entry PSA of 1.6-4. Median follow up was 12.6 years. Actuarial overall survival at 10 years was 82% for RT plus AAT and 78% for RT + placebo and a hazard ratio of 0.75 (95% CI: 0.58-0.98) with a 1-sided p value of 0.018 (2-sided p = 0.036). The 12-year incidence of PC central-reviewed deaths were 2.3% for RT + AAT and 7.5% for RT + placebo ( p< 0.001).The cumulative incidence of metastatic PC at 12 years was less in the RT + AAT arm, 14% (51 patients), vs. 23% (83 patients) in the RT + placebo arm (p < 0.001). Subgroup analyses of the relative benefits of the addition of AAT to RT are planned and will be presented. Late grade III and IV toxicity were similar in the AAT and placebo arms. The combined grade III and IV toxicities for RT + AAT and RT + placebo were: bladder 7.0% vs. 6.7%, bowel 2.7% vs. 1.6%. Gynecomastia differed significantly by treatment arm, 70% vs. 11%. Conclusions: 24 months of AAT using 150mg bicalutamide daily during and after salvage RT significantly improved long term overall survival and reduced the incidence of metastatic PC and PC death. Support: NCI grants U10CA21661, U10CA180868, U10CA180822, and U10CA37422 and AstraZeneca. Clinical trial information: NCT00002874.

Rituximab improves outcomes for persons with lymphoproliferative disorders and is increasingly used to treat immune-mediated illnesses. Recent reports describe 2 patients with systemic lupus erythematosus and 1 with rheumatoid arthritis who developed progressive multifocal leukoencephalopathy (PML) after rituximab treatment. We reviewed PML case descriptions among patients treated with rituximab from the Food and Drug Administration, the manufacturer, physicians, and a literature review from 1997 to 2008. Overall, 52 patients with lymphoproliferative disorders, 2 patients with systemic lupus erythematosus, 1 patient with rheumatoid arthritis, 1 patient with an idiopathic autoimmune pancytopenia, and 1 patient with immune thrombocytopenia developed PML after treatment with rituximab and other agents. Other treatments included hematopoietic stem cell transplantation (7 patients), purine analogs (26 patients), or alkylating agents (39 patients). One patient with an autoimmune hemolytic anemia developed PML after treatment with corticosteroids and rituximab, and 1 patient with an autoimmune pancytopenia developed PML after treatment with corticosteroids, azathioprine, and rituximab. Median time from last rituximab dose to PML diagnosis was 5.5 months. Median time to death after PML diagnosis was 2.0 months. The case-fatality rate was 90%. Awareness is needed of the potential for PML among rituximab-treated persons.