O’Meara, Megan M.

3010 Background: Our initial vaccine studies showed that optimally treated breast cancer patients can be immunized against HER2 during active immunization. The majority of patients developed T-cell immunity to HER2 peptides and protein and also epitope spreading (ES). The goal of this study was to determine if patients previously immunized with a HER2 vaccine had persistent immunity years after active immunization and to assess their clinical outcome in terms of overall survival (OS). Methods: Subjects eligible for this IRB-approved long term follow-up (LTFU) study: (1) had HER2+ breast cancer and were immunized between 1996–1999 in a phase I HER2 peptide vaccine trial, (2) were at least 1 year out from their last vaccine, and (3) if donating blood samples could not be receiving chemotherapy. 52 patients (37 stage IV, 15 stage III) were identified and 21/52 patients (12 stage IV, 9 stage III) were determined to be living. All 21 subjects were contacted by letter and sent a LTFU Questionnaire. OS was defined as the time between date of vaccine study entry and death or last follow-up and was estimated using the Kaplan-Meier method. Cox proportional hazards were used to determine associations between OS and known clinical and vaccine-related immunologic factors; analyses included all 52 subjects. Long-term T-cell immunity was evaluated using IFN-γ ELISPOT assay. Results: Median follow-up time for the 21 patients still alive was 112 months (range, 104–126 months). Blood samples were collected in 10/21 subjects and 6/8 (75%) evaluble patients had persistent T-cell immunity to immunizing HER2 peptides; and 7/8 patients (88%) had T-cell immunity specific for HER2 protein and peptides not contained in their immunizing mix (defined as ES). In multivariate analysis, number of chemotherapy regimens prior to vaccination (HR=5.7 (CI 95%, 1.5–23; p=<0.001)), and development of ES after HER2 vaccination (HR=0.34 (CI 95%, 0.12–1.0; p=0.05)) were independent predictors of OS. Median OS for 33 subjects who developed ES was 84 months vs 25 months for 16 subjects who did not develop ES. Conclusions: HER2-specific T-cell immunity elicited with active immunization is durable years after vaccination has ended and the generation of ES is an independent predictor of OS. No significant financial relationships to disclose.

Abstract Abstract 798 Hodgkin lymphoma (HL) is a lymphoid neoplasm associated with the presence of CD30-positive Hodgkin Reed-Sternberg cells in a background of inflammatory cells. The regimen containing doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) has become a common standard of care for the frontline treatment of HL. However, although ABVD is curative for the majority of patients with advanced stage HL, up to 30% of patients will require a salvage therapy. Brentuximab vedotin (ADCETRIS®) comprises an anti-CD30 monoclonal antibody conjugated by a protease-cleavable linker to a microtubule-disrupting agent, monomethyl auristatin E (MMAE). This phase 1, open-label, multicenter study was conducted to evaluate the safety of brentuximab vedotin when administered in combination with standard therapy (ABVD) or a modified standard (AVD) (ClinicalTrials.gov NCT01060904). Patients received doses of 0.6, 0.9, or 1.2 mg/kg brentuximab vedotin with standard doses of ABVD or 1.2 mg/kg brentuximab vedotin with AVD, depending upon cohort assignment. The combination regimens were administered on Days 1 and 15 of each 28-day cycle for up to 6 cycles of therapy. Each regimen evaluated a dose limiting toxicity (DLT) period, defined as any Cycle 1 toxicity requiring a delay of ≥ 7 days in standard ABVD or AVD therapy. Determination of antitumor activity was based on investigator assessment of objective response according to the Revised Response Criteria for Malignant Lymphoma (Cheson 2007). FDG-PET interpretation for Cycle 2 was performed by a central review per Deauville criteria with uptake above liver background considered positive. Data are presented for the 51 patients treated. Six patients received 0.6 mg/kg, 13 received 0.9 mg/kg, and 6 received 1.2 mg/kg with ABVD; 26 patients received 1.2 mg/kg with AVD. Overall, 37 patients were male (73%) and the median age of all patients was 33 years (range, 18–59). At baseline, 45% of all patients had Stage IV HL, 25% had an IPS score ≥4, and all patients with available ECOG status had a score of 0 or 1. No DLT was observed up to 1.2 mg/kg in either regimen. Common AEs (≥20 patients overall) noted in the ABVD and AVD cohorts, respectively, were nausea (76%, 77%), neutropenia (80%, 69%), peripheral sensory neuropathy (72%, 65%), vomiting (60%, 38%), fatigue (44%, 46%), and constipation (48%, 31%). Common ≥Grade 3 AEs (>10% of patients overall) observed in the ABVD and AVD cohorts, respectively, were neutropenia (80%, 65%), anemia (20%, 12%), febrile neutropenia (20%, 8%), and pulmonary toxicity (24%, 0%). In the ABVD cohorts, 11/25 (44%) patients had AEs of pulmonary toxicity, interstitial lung disease, or pneumonitis that led to discontinuation of bleomycin; 2 of these events led to death. Of these 11 patients, 7 completed treatment with AVD and brentuximab vedotin. In general, these events occurred between Cycles 3 and 6. No pulmonary toxicity was observed in the AVD cohort. The incidence of neuropathy was similar between the ABVD (72%) and AVD (73%) regimens; none of these events were ≥Grade 4 in severity. Overall, 7 patients discontinued brentuximab vedotin due to an AE (5 ABVD patients and 2 AVD patients). At Cycle 2, 48 patients were evaluated by FDG-PET by central review; of these, all 22 ABVD and 24/26 AVD patients were PET negative. Of the 51 patients treated, 4 withdrew consent or were lost to follow-up prior to end of treatment (EOT) assessments. The remaining 47 patients had a 96% objective response rate: 21/22 ABVD patients (95%) and 23/25 AVD patients (92%) achieved CR at the end of frontline therapy, 1 AVD patient had PR (with further workup ongoing), 1 ABVD patient died of AEs (hyponatremia and pulmonary toxicity) prior to EOT, and 1 AVD patient had PD. In patients with newly diagnosed HL, the maximum tolerated dose of brentuximab vedotin combined with ABVD or AVD was not reached; no DLT was observed up to 1.2 mg/kg every 2 weeks, the maximum planned dose. The safety profile observed confirmed that brentuximab vedotin can be safely combined with AVD; however, combination with a bleomycin-containing regimen is not recommended due to the incidence of pulmonary toxicity. The very high CR rate seen in this cohort of advanced-stage HL patients compares favorably with historical controls and warrants comparison with standard therapy. A phase 3 study comparing brentuximab vedotin combined with AVD versus ABVD alone is planned. Disclosures: Ansell: Seattle Genetics, Inc.: Research Funding; Celgene Corporation: Consultancy. Off Label Use: Brentuximab vedotin is indicated for treatment of patients with Hodgkin lymphoma after failure of autologous stem cell transplant or after failure of at least two prior multi-agent chemotherapy regimens in patients who are not ASCT candidates and for the treatment of patients with systemic anaplastic large cell lymphoma after failure of at least one prior multi-agent chemotherapy regimen. These indications are based on response rate. There are no data available demonstrating improvement in patient reported outcomes or survival with brentuximab vedotin. Connors:Seattle Genetics, Inc.: Research Funding. Park:Seattle Genetics, Inc.: Membership on an entity's Board of Directors or advisory committees, Research Funding; Teva: Research Funding. O'Meara:Seattle Genetics, Inc.: Employment, Equity Ownership. Younes:Seattle Genetics, Inc.: Consultancy, Research Funding; Celgene: Honoraria; Novartis: Honoraria, Research Funding; Affimed: Research Funding; Gilead: Research Funding.