Modiano, Manuel

LBA8003 The full, final text of this abstract will be available at abstract.asco.org at 7:30 AM (EDT) on Monday, June 3, 2013, and in the Annual Meeting Proceedings online supplement to the June 20, 2013, issue of Journal of Clinical Oncology. Onsite at the Meeting, this abstract will be printed in the Monday edition of ASCO Daily News.

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.

LBA8003 Background: PemC and PCB are regimens used for first-line treatment of advanced NS-NSCLC. The primary objective was to compare progression-free survival without Grade 4 toxicity (G4PFS) between two vs three drug regimen arms. Methods: Patients ≥18 years, Stage IV NS NSCLC, AJCC (v7.0), and ECOG PS 0/1 were enrolled. Patients were randomized (1:1); received 4 cycles of induction (PemC: Pem, 500 mg/m2 and C, AUC = 6; PCB: P, 200 mg/m2, C, AUC = 6, and B, 15 mg/kg) followed by Pem (PemC Arm) or B (PCB Arm) maintenance therapy in the absence of progressive disease or discontinuation. Secondary endpoints were PFS, overall survival (OS), overall response rate (ORR), and disease control rate (DCR). The study was powered for G4PFS; assuming hazard ratio (HR) of 0.75; there was 80% power to detect superiority of PemC over PCB with a 2-sided type I error of 0.10. Efficacy data were analyzed by intent-to-treat principle using the log-rank test for time-to-event variables, and an exact test for ORR and DCR. Safety data were evaluated using CTCAE v3 for patients who received ≥1 dose of study treatment. Results: Patients were randomized to PemC (N = 182) or PCB (N = 179). Baseline factors were balanced between arms: median age 66/66 years; % female 42/42; % PS=0, 47/47; % stage IV M1a 29/30; for PemC vs PCB, median G4PFS (months) was 3.91/2.86 (HR = 0.85, 90% CI 0.7, 1.04, p = 0.176); PFS and OS had HR = 1.06 (95% CI 0.84, 1.35), p = 0.610, and HR = 1.07 (95% CI 0.83, 1.36), p = 0.616, respectively. The ORR (%) 23.6/ 27.4 and DCR (%) 59.9/57.0 were for PemC vs PCB, respectively. Significantly more drug-related grade 3/4 anemia (18.7% vs 5.4%), and thrombocytopenia (24.0% vs 9.6%) were seen on PemC; significantly more grade 3/4 neutropenia (48.8% vs 24.6%) and grade 1/2 alopecia (28.3 % vs 8.2%) were seen on PCB. Conclusions: PemC was not superior to PCB in G4PFS; no difference in PFS or OS was observed for the two- vs three-drug regimens. There were no unexpected toxicities; the toxicity profiles demonstrated distinctions by arm, and both regimens demonstrated tolerability. Clinical trial information: NCT00948675.