Taft, David R.

AbstractThis phase 1-2 study evaluated brentuximab vedotin (BV) combined with nivolumab (Nivo) as first salvage therapy in patients with relapsed/refractory (r/r) classical Hodgkin lymphoma (cHL). In parts 1 and 2, patients received staggered dosing of BV and Nivo in cycle 1, followed by same-day dosing in cycles 2 to 4. In part 3, both study drugs were dosed, same day, for all 4 cycles. At end of study treatment, patients could undergo autologous stem cell transplantation (ASCT) per investigator discretion. The objective response rate (ORR; N = 91) was 85%, with 67% achieving a complete response (CR). At a median follow-up of 34.3 months, the estimated progression-free survival (PFS) rate at 3 years was 77% (95% confidence interval [CI], 65% to 86%) and 91% (95% CI, 79% to 96%) for patients undergoing ASCT directly after study treatment. Overall survival at 3 years was 93% (95% CI, 85% to 97%). The most common adverse events (AEs) prior to ASCT were nausea (52%) and infusion-related reactions (43%), all grade 1 or 2. A total of 16 patients (18%) had immune-related AEs that required systemic corticosteroid treatment. Peripheral blood immune signatures were consistent with an activated T-cell response. Median gene expression of CD30 in tumors was higher in patients who responded compared with those who did not. Longer-term follow-up of BV and Nivo as a first salvage regimen shows durable efficacy and impressive PFS, especially in patients who proceeded directly to transplant, without additional toxicity concerns. This trial was registered at www.clinicaltrials.gov as #NCT02572167.

Abstract Introduction Brentuximab vedotin (BV) is an ADC directed against CD30, a receptor expressed by malignant Reed-Sternberg (RS) cells present in the inflammatory/immune cell microenvironment of classical Hodgkin lymphomas (cHL). Through induction of immunogenic cell death, BV may prime an antitumor immune response via microtubule disruption of CD30-expressing RS cells (Gardai 2015). Tumor cells expressing PD-1 ligands use the PD-1 pathway to evade an immune response. Nivolumab (Nivo) blocks the PD-1 receptor, inhibits binding of PD-1 ligands, and restores an effective antitumor immune response. Targeted killing of CD30-expressing RS cells, concurrent with restoration of the immune response, may lead to higher complete response (CR) rates in patients (pts) with relapsed or refractory cHL (R/R HL), as well as improved durability of responses post autologous stem cell transplant (ASCT). Here we present updated results from the phase 1/2 study of BV + Nivo in pts with R/R HL. Methods BV + Nivo was evaluated in cHL that had relapsed or was refractory to frontline (FL) chemotherapy in adult pts (NCT02572167). Pts were excluded if they had received prior salvage therapy, BV or immuno-oncology therapy, or allogeneic SCT or ASCT. Pts were treated in 21-day cycles for up to 4 cycles. In Parts 1 and 2 of the trial, BV (1.8 mg/kg) was given on Cycle 1 Day 1 and Nivo (3 mg/kg) on Cycle 1 Day 8. For Cycles 2-4, BV and Nivo were given on Day 1. After the Cycle 4 response assessment, pts were eligible to undergo ASCT. The investigators assessed response per the Lugano Classification (Cheson 2014). Results 62 pts with R/R HL were enrolled in Parts 1 and 2; 61 pts received BV + Nivo, of whom 58 completed treatment (tx). 4 pts discontinued the study due to pt decision (2), AE (1), and investigator decision (1). Median age was 36 years, 52% were female, and 90% had received FL ABVD. 45% of pts had primary refractory disease and 31% experienced relapse within 1 year of FL therapy. Infusion-related reactions (IRRs) occurred in 41% of pts. Tx emergent AEs occurred in 98% of pts prior to ASCT (33% G3, 5% G4). Excluding IRRs, potential immune-related AEs (IrAEs) occurred in 84% of pts (10% G3, 3% G4) with 5 pts (8%) treated with systemic steroids for G4 pneumonitis, G4 pneumonitis and colitis, G2 pneumonitis, G3 diarrhea and G2 colitis, and G3 AST elevation. Among the 60 efficacy-evaluable pts, the CR rate was 62%, (48% of CR pts had Deauville ≤ 2) with an objective response rate of 85%; 5 pts (8%) had stable disease and 4 pts (7%) progressed on tx. At the time of this analysis, 39 pts had initiated ASCT with a median 5.1x106 CD34+ cells/kg (range; 3-60) collected. Median times to neutrophil and platelet engraftment were 12 and 15 days, respectively. Pts were followed for a median of 3 months from ASCT (N=39, range; 0-12) and 5.7 months from first dose (N=61, range; 1-17). BV and Nivo effects on the immune system were evaluated by peripheral blood immunophenotyping, serum cytokine/chemokine analyses, T-cell receptor sequencing, and intracellular cytokine staining. The first dose of BV resulted in elevation of pro-inflammatory cytokines and chemokines and concurrent reduction in serum TARC levels, with these results maintained post Nivo. We observed a reduction in Tregs and other T cell subsets after the first dose of BV with an elevation of T cell subsets post BV + Nivo. While TCR clonality in the periphery did not change over the course of the trial, T cell clonal expansion was observed post BV + Nivo, concurrent with T cell elevation measured by flow cytometry. Ex vivo peptide stimulation of PBMCs isolated from blood revealed the enhanced ability of T cell subsets to respond to MHC I and MHC II antigens following BV + Nivo compared to baseline: e.g., effector memory CD8+ T cells from some pts displayed increased intracellular IL-2, and TNFa after stimulation with MHCI and MHCII peptide pools compared to baseline, potentially indicating elevated activation status of the immune system following combination tx. Conclusion R/R HL remains an unmet clinical need despite recent medical advances. These data suggest the combination BV + Nivo is a well tolerated and an active salvage therapy with a high rate of CR (62%) that has no adverse impact on stem cell collection. The safety and activity of this novel combination support further exploration in an ongoing pivotal phase 3 trial in pts with R/R HL who have either already received or are considered ineligible for ASCT (NCT03138499). Disclosures Herrera: Seattle Genetics: Research Funding; Merck: Consultancy; Genentech: Consultancy; BMS: Consultancy; Pharmacyclics: Consultancy. Moskowitz: Seattle Genetics: Honoraria, Research Funding; Takeda: Honoraria; Incyte: Research Funding; ADC Therapeutics: Research Funding; Bristol Myers-Squibb: Consultancy, Research Funding. Bartlett: Novartis: Research Funding; ImaginAB: Research Funding; Astra Zeneca: Research Funding; Millenium: Research Funding; Janssen: Research Funding; Pharmacyclics: Research Funding; Affimed: Research Funding; Forty Seven: Research Funding; Immune Design: Research Funding; Bristol-Meyers Squibb: Research Funding; Merck & Co: Research Funding; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees; Genentech: Research Funding; Seattle Genetics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Research Funding. Vose: Merck: Research Funding; Kite: Research Funding; Janssen: Research Funding; Celgene: Research Funding; Allos Therapeutics: Research Funding; Acerta: Research Funding; Incyte: Research Funding; Onyx: Research Funding; Seattle Genetics: Research Funding; US Biotest: Research Funding; Bristol-Myers Squibb: Research Funding. Ramchandren: Seattle Genetics: Consultancy; MERCK: Research Funding; Pharmacyclics: Research Funding; Janssen: Research Funding. Feldman: AbbVie: Speakers Bureau; Janssen: Speakers Bureau; Kite Pharma: Speakers Bureau; Celgene: Speakers Bureau; Pharmacyclics: Speakers Bureau; Seattle Genetics: Honoraria, Research Funding, Speakers Bureau; Bristol-Myers Squibb: Consultancy. LaCasce: BMS: Consultancy; Forty Seven: Consultancy, Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Consultancy, Research Funding. Ansell: Merck: Research Funding; Bristol-Myers Squibb: Research Funding; Celldex: Research Funding; Seattle Genetics: Research Funding; Affimed: Research Funding. Moskowitz: Celgene: Consultancy; Seattle Genetics: Consultancy, Other: Ad Board, Research Funding; Genentech BioOncology: Consultancy; Pharmacyclics: Research Funding; Merck: Consultancy, Research Funding. Fenton: Seattle Genetics: Employment, Equity Ownership. Ogden: Seattle Genetics: Employment, Equity Ownership. Taft: Seattle Genetics: Employment, Research Funding. Zhang: Seattle Genetics: Employment, Research Funding. Kato: Bristol-Myers Squibb: Employment, Equity Ownership; Seattle Genetic: Research Funding. Campbell: Seattle Genetics: Employment, Equity Ownership; CTI BioPharma: Employment, Equity Ownership. Advani: Agensys: Research Funding; Pharmacyclics: Research Funding; Regeneron: Research Funding; FortySeven: Research Funding; Nanostring: Consultancy; Celgene: Research Funding; Pharmacyclics: Consultancy; Merck: Research Funding; Juno Therapeutics: Consultancy; Kura: Research Funding; Janssen: Research Funding; Millennium: Research Funding; Seattle Genetics: Research Funding; Gilead: Consultancy; Bristol-Myers Squibb: Consultancy, Research Funding; Spectrum: Consultancy; Bayer Healthcare Pharmaceuticals: Research Funding; Infinity: Research Funding; Genentech: Research Funding; Cell Medica: Research Funding; Sutro: Consultancy.

Introduction Brentuximab vedotin (BV) targets CD30, a receptor expressed on the Reed-Sternberg cells of classic Hodgkin lymphoma (cHL). Nivolumab (Nivo) restores antitumor immunity by blocking the PD-1 receptor on activated T-cells. In this phase 1/2 study, combination treatment (tx) with BV + Nivo demonstrated durable efficacy in patients (pts) with relapsed/refractory (R/R) cHL (Herrera, Blood 2018; NCT02572167). Biomarkers consistent with innate and adaptive immune activation were observed in the peripheral blood of pts treated with the combination regimen. Herein, we associate biomarkers in the peripheral blood with clinical response, and present follow-up results for pts who received BV + Nivo under staggered and concurrent dosing schedules. Methods Enrolled pts had cHL that relapsed or was refractory to frontline chemotherapy. In Parts 1 and 2 (staggered dosing), pts received up to 4 cycles of BV 1.8 mg/kg and Nivo 3.0 mg/kg given on Days 1 and 8 of Cycle 1, respectively, and together on Day 1 of Cycles 2-4. Pts in Part 3 (concurrent dosing) received the same dose of both agents on Day 1 of all 4 cycles. After investigators assessed response (Cheson 2014, with the incorporation of LYRIC [Cheson 2016] for pts in Part 3), pts could undergo ASCT. Results Demographics and baseline characteristics were similar across all treated pts (N=91) in the staggered and concurrent dosing cohorts; median age 34 years (yrs, range; 18-69), 42% with primary refractory disease, and 30% with relapse within 1 yr of frontline therapy. All 91 pts are off-tx and have been observed through the 100-day safety reporting period. A total of 86 pts (92%) completed all 4 cycles of BV + Nivo. Early tx discontinuations were due to; AE (peripheral neuropathy and increased GGT [1 pt each]), progressive disease (PD), investigator decision, and pt decision (1 pt each). Most common AEs prior to ASCT or additional salvage therapy were nausea (52%) and infusion-related reactions (IRRs, 43%). Excluding IRRs, 14% of pts had immune-related AEs requiring tx with systemic steroids, including rash (8%), pneumonitis (4%), and AST increased, diarrhea, and Guillain-Barre syndrome (1% each). The ORR for all-treated pts was 85%, with 67% complete response (CR). A total of 67 pts (74%) underwent ASCT after tx with BV + Nivo. There were 22 pts who received additional salvage therapy after BV + Nivo (7 PD, 6 partial response, 5 stable disease, and 4 CR at EOT), 17 of whom later underwent ASCT. At a median of 22.6 months (range; 1.2, 41.2) from the start of tx, the estimated 2-yr PFS rate in all treated pts was 78%, and for pts who underwent ASCT after tx with BV + Nivo was 91% (Figure 1). At 2 years, the estimated OS rate for all treated pts was 93%. Staggered and concurrent dosing of BV + Nivo resulted in increased levels of activated and dividing CD4+ T cells, activated and dividing CD8+ T cells (concurrent dosing-only), regulatory T cells (Tregs), and circulating plasmablasts in blood. We did not observe any associations between the magnitude of these changes and clinical response. Pts with CR exhibited trends for higher pre-tx blood levels of CD30+ Tregs and CD30+ Th subsets compared to pts without CR, suggesting BV depletion of these populations may have a role in the clinical mode of action of BV + Nivo. Although pre-tx levels of cytotoxic lymphocytes (CTLs) in blood did not differentiate pts with CR from other pts, pts in the lower quartile of pre-tx CTL levels showed significantly shorter PFS than other pts, suggesting a potential association between CTLs and disease control. Changes in blood cytokine and chemokine levels were observed after BV + Nivo, including increased levels of IL-18, IP-10, I-TAC, and sCD30, and decreased levels of TARC, IL-2Ra, and IL-6. Our analyses support strong correlations between pre-tx cytokine/chemokine levels and clinical benefit including trends linking lower pre-tx levels of IL-18, I-TAC, and IL-2RA to achieving CR and longer PFS. Conclusion BV + Nivo, both staggered and current dosing, showed tolerability and high CR rates with durable remissions among pts with R/R cHL. Analysis of blood biomarkers identified trends potentially linking baseline levels of CD30+ immune cells and the baseline pt inflammatory state with the activity of BV + Nivo. Together, these encouraging results support further investigation of BV + Nivo as initial salvage therapy in pts with R/R cHL. Figure 1 Disclosures Moskowitz: Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Erytech Pharma: Consultancy; Erytech Pharma: Consultancy; ADC Therapeutics: Consultancy; Merck: Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Merck: Research Funding; Merck: Research Funding; Cell Medica: Consultancy; Takeda Pharmaceuticals: Consultancy; Merck: Research Funding; ADC Therapeutics: Consultancy; Bristol-Myers Squibb: Consultancy, Research Funding; Erytech Pharma: Consultancy; Takeda Pharmaceuticals: Consultancy; Incyte: Research Funding; Merck: Research Funding; Merck: Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Cell Medica: Consultancy; Takeda Pharmaceuticals: Consultancy; Cell Medica: Consultancy; ADC Therapeutics: Consultancy; Incyte: Research Funding; Takeda Pharmaceuticals: Consultancy; Takeda Pharmaceuticals: Consultancy; Merck: Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Cell Medica: Consultancy; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Takeda Pharmaceuticals: Consultancy; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Cell Medica: Consultancy; miRagen Therapeutics Inc: Consultancy, Research Funding; Incyte: Research Funding; Takeda Pharmaceuticals: Consultancy; Seattle Genetics: Consultancy, Honoraria, Research Funding; Takeda Pharmaceuticals: Consultancy; Cell Medica: Consultancy; ADC Therapeutics: Consultancy; Erytech Pharma: Consultancy; Erytech Pharma: Consultancy; Erytech Pharma: Consultancy; Bristol-Myers Squibb: Consultancy, Research Funding; Erytech Pharma: Consultancy; Bristol-Myers Squibb: Consultancy, Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; Incyte: Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; Incyte: Research Funding; Cell Medica: Consultancy; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Erytech Pharma: Consultancy; Takeda Pharmaceuticals: Consultancy; Takeda Pharmaceuticals: Consultancy; Merck: Research Funding; Takeda Pharmaceuticals: Consultancy; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Incyte: Research Funding; Cell Medica: Consultancy; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Incyte: Research Funding; ADC Therapeutics: Consultancy; Merck: Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; ADC Therapeutics: Consultancy; Incyte: Research Funding; Incyte: Research Funding; Cell Medica: Consultancy; Incyte: Research Funding; ADC Therapeutics: Consultancy; Erytech Pharma: Consultancy; Bristol-Myers Squibb: Consultancy, Research Funding; Erytech Pharma: Consultancy; Takeda Pharmaceuticals: Consultancy; Takeda Pharmaceuticals: Consultancy; Cell Medica: Consultancy; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Takeda Pharmaceuticals: Consultancy; Cell Medica: Consultancy; Erytech Pharma: Consultancy; Seattle Genetics: Consultancy, Honoraria, Research Funding; Erytech Pharma: Consultancy; Seattle Genetics: Consultancy, Honoraria, Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; Merck: Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; Merck: Research Funding; Cell Medica: Consultancy; Seattle Genetics: Consultancy, Honoraria, Research Funding; Incyte: Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; Incyte: Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; Kyowa Hakko Kirin Pharma: Consultancy, Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; Incyte: Research Funding; ADC Therapeutics: Consultancy; Bristol-Myers Squibb: Consultancy, Research Funding; Erytech Pharma: Consultancy; Erytech Pharma: Consultancy; ADC Therapeutics: Consultancy; Incyte: Research Funding; ADC Therapeutics: Consultancy; miRagen Therapeutics Inc: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; ADC Therapeutics: Consultancy; ADC Therapeutics: Consultancy; ADC Therapeutics: Consultancy; Bristol-Myers Squibb: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; miRagen Therapeutics Inc: Consultancy, Research Funding; Cell Medica: Consultancy; Cell Medica: Consultancy; Seattle Genetics: Consultancy, Honoraria, Research Funding; Merck: Research Funding; Incyte: Research Funding; Merck: Research Funding; Merck: Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Erytech Pharma: Consultancy; Takeda Pharmaceuticals: Consultancy; ADC Therapeutics: Consultancy; Cell Medica: Consultancy; Seattle Genetics: Consultancy, Honoraria, Research Funding; Merck: Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; ADC Therapeutics: Consultancy; Seattle Genetics: Consultancy, Honoraria, Research Funding. Advani:Celmed: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Research Funding; Forty-Seven: Research Funding; Infinity Pharma: Research Funding; Pharmacyclics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead Sciences, Inc./Kite Pharma, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees; Regeneron: Research Funding; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees; Kyowa Kirin Pharmaceutical Developments, Inc.: Consultancy; Merck: Research Funding; Kura: Research Funding; Bayer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Research Funding; Autolus: Consultancy, Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees; Agensys: Research Funding; Cell Medica, Ltd: Consultancy; Stanford University: Employment, Equity Ownership; Seattle Genetics: Consultancy, Research Funding; Millennium: Research Funding; Janssen: Research Funding; Roche/Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Bartlett:Affimed Therapeutics: Research Funding; Bristol-Myers Squibb: Research Funding; Celgene: Research Funding; Dynavax: Research Funding; Forty-Seven: Research Funding; Genentech: Research Funding; Gilead: Research Funding; Immune Design: Research Funding; Janssen: Research Funding; Kite Pharma: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Medimmune: Research Funding; Merck: Research Funding; Millennium: Research Funding; Novartis: Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Research Funding; Seattle Genetics, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Vose:Acerta Pharma: Honoraria, Other: Grants, Research Funding; Bristol-Meyers Squibb Company: Research Funding; Celgene Corporation: Research Funding; Incyte Corporation: Research Funding; Kite Pharma: Honoraria, Other: Grants, Research Funding; Novartis: Research Funding; Seattle Genetics: Research Funding; AbbVie: Consultancy, Honoraria; Epizyme: Consultancy, Honoraria; Legend Pharmaceuticals: Honoraria. Ramchandren:Genentech: Research Funding; Seattle Genetics, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen: Research Funding; Pharmacyclics LLC, an Abbvie company: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Research Funding; Sandoz-Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees. Feldman:Takeda: Honoraria, Speakers Bureau; Celgene: Honoraria, Research Funding, Speakers Bureau; Seattle Genetics: Consultancy, Honoraria, Other: Travel expenses, Speakers Bureau; AbbVie: Honoraria, Other: Travel expenses, Speakers Bureau; Pharmacyclics: Honoraria, Other: Travel expenses, Speakers Bureau; Janssen: Honoraria, Speakers Bureau; Kite Pharma: Honoraria, Other: Travel expenses, Speakers Bureau; Bayer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding; Cell Medica: Research Funding; Roche: Research Funding; Corvus: Research Funding; Eisai: Research Funding; Kyowa Hakko Kirin: Research Funding; Pfizer: Research Funding; Portola Pharma: Research Funding; Roche: Research Funding; Trillium: Research Funding; Viracta: Research Funding. LaCasce:BMS: Consultancy; Research to Practice: Speakers Bureau; Humanigen: Consultancy; Seattle Genetics: Consultancy, Research Funding. Christian:Bristol-Myers Squibb: Research Funding; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech: Membership on an entity's Board of Directors or advisory committees, Research Funding; Cephalon: Research Funding; Janssen: Research Funding; Immunomedics: Research Funding; Celgene: Research Funding; Acerta: Research Funding; Triphase: Research Funding; Millennium Pharmaceuticals Inc: Research Funding; Merck: Research Funding. Ansell:Bristol-Myers Squibb: Research Funding; LAM Therapeutics: Research Funding; Seattle Genetics: Research Funding; Regeneron: Research Funding; Trillium: Research Funding; Seattle Genetics: Research Funding; Mayo Clinic Rochester: Employment; Affimed: Research Funding; Regeneron: Research Funding; Trillium: Research Funding; Mayo Clinic Rochester: Employment; Bristol-Myers Squibb: Research Funding; LAM Therapeutics: Research Funding; Affimed: Research Funding. Moskowitz:ADC Therapeutics: Research Funding; Merck: Consultancy, Research Funding; Seattle Genetics, Inc.: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; Celgene: Consultancy; Pharmacyclics: Research Funding. Brown:Seattle Genetics, Inc.: Employment, Equity Ownership. Taft:Seattle Genetics, Inc.: Employment, Equity Ownership. Ansari:Seattle Genetics, Inc.: Employment, Equity Ownership. Zak:Seattle Genetics, Inc.: Employment, Equity Ownership. Sacchi:Seattle Genetics, Inc.: Research Funding. Manley:Seattle Genetics: Employment, Equity Ownership. Herrera:Merck: Consultancy, Research Funding; AstraZeneca: Research Funding; Adaptive Biotechnologies: Consultancy; Pharmacyclics: Research Funding; Immune Design: Research Funding; Kite Pharma: Consultancy, Research Funding; Genentech, Inc.: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Gilead Sciences: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding.

Abstract Introduction This phase 1/2 study evaluated the safety and antitumor activity of brentuximab vedotin (BV) administered in combination with nivolumab (Nivo) in adult patients (pts) with relapsed/refractory classic Hodgkin lymphoma (R/R cHL) who have failed frontline therapy (NCT02572167). Results from Parts 1 & 2 have been previously reported, wherein safety, efficacy, and biomarkers consistent with immune activation were observed in pts with R/R cHL (Herrera et al., Blood 2018). In Part 3, patients were treated with BV + Nivo on Day 1 of each cycle. In contrast, pts in Parts 1 & 2 received BV on C1D1 and Nivo on C1D8 with concurrent admin on subsequent cycles. Herein we present safety, efficacy, and biomarker results for Part 3 and updated progression free survival (PFS) from Parts 1 & 2. Methods Pts in Parts 1 & 2 received up to four 21-day cycles of staggered dosing (day 1 BV 1.8 mg/kg, day 8 Nivo 3 mg/kg in Cycle 1) and concurrent thereafter, with steroid and antihistamine premedication. Pts in Part 3 received up to four 21-day cycles of concurrent BV + Nivo on Day 1 with antihistamine premedication. Following Cycle 4 response assessment (Lugano Classification Revised Staging System with the incorporation of the Lymphoma Response to Immunomodulatory Therapy Criteria [LYRIC, 2016]) responding pts were eligible to undergo autologous stem cell transplant (ASCT). Results 30 pts were treated in Part 3 and all were evaluable for efficacy. Pt characteristics included the following: median age 31.5 yrs (range; 20 - 66), 63% female, 93% prior ABVD, 37% primary refractory HL, 30% relapsed within 1year of frontline therapy, 30% with extranodal disease and 17% with bulky disease at enrollment. 28 pts completed all 4 cycles. 1 pt discontinued treatment (tx) due to an adverse event (AE; Grade 3 [G3] elevated Gamma-Glutamyltransferase) and 1 pt due to progressive disease (PD). The latter pt eventually died due to PD. All pts are off tx and have been observed through the safety reporting period. 37% of pts experienced a G3 or higher tx emergent AE prior to ASCT. 30% of the pts experienced infusion related reactions (IRRs), which occurred most frequently during Cycle 2. Potential G3 or higher immune-related AEs (IRAEs), excluding IRRs, occurred in 2 pts, one of whom required steroids for G4 pneumonitis, which subsequently resolved. Among the 30 efficacy evaluable pts, the complete response (CR) rate was 80% (24/30), with an objective response rate (ORR) of 93%. 47% of pts (14) had a Deauville ≤2, and 17% (5) had Deauville 3. 5 pts with CR had a Deauville >3 and met LYRIC criteria for IR-2. 4/5 pts had a negative follow-up biopsy that confirmed CR and in 1 pt the PET finding was considered to be a false positive as contrast enhanced CT did not reveal any abnormality. All 5 pts proceeded directly to ASCT and remain in CR at follow-up. Among all treated patients, 25 went directly to ASCT after completing BV + Nivo tx with a median 6.8 x 106 CD34+ cells/kg (range 1-20) collected. Median times to neutrophil and platelet engraftment were 12 and 14 days, respectively. 4 pts required additional salvage therapy subsequent to study tx. Patients were followed for a median of 6 months from ASCT (N=25, range 0.8-8.8) and 10 months from first dose (N=30, range 1.8-12.7). The estimated 9-month PFS rate in all-treated pts was 88%. This is comparable to all-treated pts in Parts 1 & 2, whose estimated 9 and 15 month PFS were 86% and 82%, respectively (Fig 2). Biomarker testing was performed on peripheral blood samples, included immunophenotyping, serum cytokine analysis, and TCRβ sequencing. Concurrent dosing of BV+ Nivo resulted in increased levels of both activated and dividing CD4+ and CD8+ T cells, as well as increased regulatory T-cells and circulating plasmablasts. Cytokines and chemokines associated with innate and adaptive immune activation, including Type I and Type II interferons, IL-18, and IP-10, were significantly upregulated following BV + Nivo, while TARC levels were significantly diminished following therapy. TCRβ sequencing revealed clonal expansion in the periphery following BV + Nivo. Conclusion A concurrent dosing schedule of BV + Nivo was well tolerated with a high CR rate of 80%. Biomarkers evaluated in Part 3 indicate immune activation in the periphery following BV + Nivo. Cumulatively, the results in Part 3, along with the durable remissions noted in Parts 1 & 2, support BV + Nivo combination as an encouraging first salvage therapy prior to ASCT in pts with R/R cHL. Disclosures Advani: Forty Seven: Research Funding; Infinity: Research Funding; Seattle Genetics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board, Research Funding; Gilead/Kite: Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board; Roche/Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board, Research Funding; Merck: Research Funding; Agensys: Research Funding; Millenium: Research Funding; Janssen: Research Funding; Celgene: Research Funding; Autolus: Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Kura: Research Funding; Kyowa: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board; Bayer: Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board; Regeneron: Research Funding; Astra Zeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board; Cell Medica: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board, Research Funding. Moskowitz:Bristol Myers-Squibb: Consultancy, Research Funding; Incyte: Research Funding; Takeda: Honoraria; Merck: Research Funding; ADC Therapeutics: Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding. Bartlett:Seattle Genetics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees. Vose:Celgene: Research Funding; Legend Pharmaceuticals: Honoraria; Bristol Myers Squibb: Research Funding; Merck Sharp & Dohme Corp.: Research Funding; Incyte Corp.: Research Funding; Roche: Honoraria; Novartis: Honoraria, Research Funding; Seattle Genetics, Inc.: Research Funding; Acerta Pharma: Research Funding; Abbvie: Honoraria; Epizyme: Honoraria; Kite Pharma: Research Funding. Ramchandren:Merck: Research Funding; Bristol-Myers Squibb: Consultancy; Seattle Genetics: Consultancy, Research Funding; Pharmacyclics LLC an AbbVie Company: Consultancy, Research Funding; Janssen: Consultancy, Research Funding. Feldman:Johnson and Johnson: Speakers Bureau; Celgene: Speakers Bureau; Pharmacyclics: Speakers Bureau; Seattle Genetics: Research Funding, Speakers Bureau; Portola: Research Funding; Janssen: Speakers Bureau; KITE: Speakers Bureau. LaCasce:Seattle Genetics: Consultancy, Honoraria; Bristol-Myers Squibb: Other: Data safety and monitoring board; Research to Practice: Speakers Bureau; Humanigen: Consultancy, Honoraria. Christian:Acerta: Research Funding; Merck: Research Funding; Bristol-Myers Squibb: Research Funding; Immunomedics: Research Funding; Celgene: Research Funding; Seattle Genetics: Research Funding; Genentech: Membership on an entity's Board of Directors or advisory committees, Research Funding. Ansell:LAM Therapeutics: Research Funding; Pfizer: Research Funding; Seattle Genetics: Research Funding; Regeneron: Research Funding; Merck & Co: Research Funding; Bristol-Myers Squibb: Research Funding; Celldex: Research Funding; Trillium: Research Funding; Affimed: Research Funding; Takeda: Research Funding. Moskowitz:Celgene: Consultancy; Merck & Co: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; Pharmacyclics: Research Funding; Seattle Genetics: Consultancy, Research Funding. Fenton:Seattle Genetics, Inc.: Employment, Equity Ownership. Ogden:Seattle Genetics, Inc: Employment, Equity Ownership. Taft:Seattle Genetics: Employment, Equity Ownership. Zak:Seattle Genetics: Employment, Equity Ownership. Sacchi:Bristol-Myers Squibb: Employment, Equity Ownership. Galderisi:Seattle Genetics: Employment, Equity Ownership. Herrera:Immune Design: Research Funding; Merck, Inc.: Consultancy, Research Funding; KiTE Pharma: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Seattle Genetics: Research Funding; AstraZeneca: Research Funding; Pharmacyclics: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; Gilead Sciences: Research Funding.

Key Points BV and Nivo were well-tolerated in patients with R/R HL, with less than 10% of patients treated with systemic steroids for immune-related AEs. The complete response rate was 61% (82% objective response rate), and patients were able to undergo stem cell transplant without adverse impact.