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Concurrent administration pembrolizumab with chemotherapy in untreated classical Hodgkin lymphoma (CHL) has not previously been studied. To investigate this combination, we conducted a single arm study of concurrent pembrolizumab with AVD (APVD) for untreated CHL. We enrolled 30 patients (6 early favorable, 6 early unfavorable, and 18 advanced stage, median age 33 years (range 18-69 years)) and met the primary safety endpoint with no observed significant treatment delays in the first two cycles. Twelve patients experienced grade 3-4 non-hematologic adverse events (AEs) most commonly febrile neutropenia (5, 17%) and infection/sepsis (3, 10%). Grade 3-4 immune-related AEs were seen in 3 patients, including ALT elevation (3, 10%) and AST elevation (1, 3%). One patient experienced an episode of grade 2 colitis and arthritis. Six (20%) patients missed at least one dose of pembrolizumab due to adverse events, primarily grade 2 or higher transaminitis (5, 17%). Among 29 response-evaluable patients, the best overall response rate was 100% and CR rate of 90%. With median follow up of 2.1 years, 2-year progression-free survival (PFS) and overall survival were 97% and 100%, respectively. To date, no patient who withheld or discontinued pembrolizumab due to toxicity has progressed. Clearance of ctDNA was associated with superior PFS when measured after cycle 2 (p=0.025) and at end of treatment (EOT, p=0.0016). None of the 4 patients with persistent disease by FDG-PET at EOT yet negative ctDNA have relapsed to date. Concurrent APVD shows promising safety and efficacy, but may yield spurious PET findings in some patients. Trial Registration Number: NCT03331341

Randomized controlled trials (RCTs) have found no evidence that the storage time of transfused red blood cell (RBC) units affects recipient survival. However, inherent difficulties in conducting RBC transfusion RCTs have prompted critique of their design, analyses, and interpretation. Here, we address these issues by emulating hypothetical randomized trials using large real-world data to further clarify the adverse effects of storage time. We estimated the comparative effect of transfusing exclusively older vs fresher RBC units on the primary outcome of death, and the secondary composite end point of thromboembolic events, or death, using inverse probability weighting. Thresholds were defined as 1, 2, 3, and 4 weeks of storage. A large Danish blood transfusion database from the period 2008 to 2018 comprising >900 000 transfusion events defined the observational data. A total of 89 799 patients receiving >340 000 RBC transfusions during 28 days of follow-up met the eligibility criteria. Treatment with RBC units exclusively fresher than 1, 2, 3, and 4 weeks of storage was found to decrease the 28-day recipient mortality with 2.44 percentage points (pp) (0.86 pp, 4.02 pp), 1.93 pp (0.85 pp, 3.02 pp), 1.06 pp (–0.20 pp, 2.33 pp), and −0.26 pp (–1.78 pp, 1.25 pp) compared with transfusing exclusively older RBC units, respectively. The 28-day risk differences for the composite end point were similar. This study suggests that transfusing exclusively older RBC units stored for >1 or 2 weeks increases the 28-day recipient mortality and risk of thromboembolism or death compared with transfusing fresher RBC units.

Background: Classical Hodgkin lymphoma (CHL) patients (pts) requiring second line therapy may still be cured with multiagent salvage chemotherapy followed by autologous stem cell transplant (ASCT). The likelihood of long-term remission following ASCT for relapsed/refractory (R/R) CHL is predicted by response to pre-ASCT salvage therapy (Moskowitz et al. Blood 2012). The anti-CD30 antibody-drug conjugate brentuximab vedotin (BV) is effective as a single agent in R/R CHL. We hypothesized that concurrent therapy with dose-dense BV and 2 cycles of ICE would be safe, efficient, and produce high CR rates necessary for superior outcomes after ASCT. (#NCT02227199) Methods: Patients (pts) ≥ 18 years old with first relapse or primary refractory CD30+ cHL were eligible for this IRB-approved prospective clinical trial. Treatment included BV on Days 1 and 8 at either 1.2 or 1.5 mg/kg (based on 3+3 dose-escalation schema; capped at 150 mg), ifosfamide and mesna 5 g/m2 each on Day 2, carboplatin AUC 5 (capped at 800 mg) on Day 2, and etoposide 100 mg/m2 daily on Days 1-3. Two 21-day cycles were given with G-CSF support. BV 1.5 mg/kg was selected as the phase II dose based on reported dose escalation data (ASH 2016, #1834). PET was performed after Cycle 2, with response assigned per Cheson 2007. Stem cells were collected after Cycle 2 at discretion of treating investigator. Peripheral blood (PB) pre- and post-treatment, stem cell (PBSC) product, and (when available) archived formalin-fixed paraffin-embedded tissue (FFPET) from presentation and relapse were collected for correlative studies. Pre-treatment PB cytokine levels were measured by Luminex. Immunohistochemistry (IHC) on FFPET identified components of inflammatory microenvironment. The primary endpoint was to determine the MTD and CR rate after 2 cycles. Secondary endpoints included PFS, OS, stem cell collection, and molecular correlates. Results: All 45 pts have enrolled and completed study treatment, including 42 pts who were assigned treatment at the MTD of 1.5 mg/kg on day 1 and 8 of each cycle. Median age was 31 (range, 21-61). 16/45 (36%) were male, 28/45 (62%) had primary refractory disease, and 11/45 (24%) had extranodal involvement at relapse. 41 pts completed both cycles of therapy. One pt experienced grade 5 multi-system organ-failure during cycle 1, one pt was removed from protocol due to non-compliance, and two pts omitted cycle 2 due to toxicity (grade 4 sepsis, grade 3 Sweet syndrome attributable to G-CSF). 2 pts received all ICE dosing, but omitted at least one dose of BV due to toxicity. In addition, 13/41 (32%) pts delayed initiation of cycle 2 by a median of 7 days (range 6-17) due to toxicity, primarily elevated transaminases (10/13, 77%). 16/45 (36%) pts experienced neuropathy, but grade ≥2 neuropathy was rare (3/45, 7%). Other grade 3-4 non-hematologic toxicity included febrile neutropenia/sepsis (11%), elevated ALT (11%), hyperglycemia (7%), pulmonary embolism (4%), and elevated AST (4%). 36 pts underwent PBSC collection at our institution and had all data available for analysis. 30/36 pts were able to collect at least 5x106 CD34+ cells/kg. 5/6 of the remaining pts were still able to proceed with ASCT with the amount collected, and the other pt was not deemed an ASCT candidate due to social reasons. 37/43 pts (86%) who were evaluable for response proceeded to ASCT (2 subjects declined ASCT, 2 were ineligible due to social issues, one was lost to follow up, one remained chemorefractory despite additional salvage chemotherapy). Only 4/37 pts who received an ASCT subsequently relapsed. 43 pts were evaluable for efficacy. Overall response rate (ORR) and CR for all enrolled patients were 91% and 74%, respectively. Among primary refractory pts, ORR and CR were 86% and 68%, respectively. With a median follow-up of 26.5 months (range 0.7-62) months, 2-year PFS and OS were 82% and 98%. Updated results will be presented at the meeting. Conclusions: BV-ICE is a rapid, active and tolerable salvage regimen for R/R CHL patients, including those with primary refractory disease. Efficacy results are comparable to previously presented BV-chemo salvage combinations often delivered over longer durations. BV-ICE should be considered in R/R CHL prior to ASCT. Figure Disclosures Lynch: Juno Therpeutics: Research Funding; TG Therapeutics: Research Funding; Takeda: Research Funding; Incyte: Research Funding; Rhizen Pharmaceuticals: Research Funding; Bayer: Research Funding; Cyteir: Research Funding; MorphoSys: Consultancy; Genentech: Research Funding. Cassaday:Merck: Research Funding; Amgen: Consultancy, Research Funding; Pfizer: Honoraria, Research Funding; Vanda Pharmaceuticals: Research Funding; Seattle Genetics: Current Employment, Current equity holder in publicly-traded company; Kite/Gilead: Consultancy, Research Funding. Smith:AstraZeneca: Research Funding; Acerta Pharma BV: Research Funding; Beigene: Consultancy; Millenium/Takeda: Consultancy; AstraZeneca: Consultancy; Seattle Genetics: Research Funding; Portola: Research Funding; Pharmacyclics: Research Funding; Merck: Research Funding; Incyte: Research Funding; Ignyta: Research Funding; Genentech: Research Funding; De Novo Biopharma: Research Funding; Bristol Meyers Squibb: Research Funding; Bayer: Research Funding; Ayala: Research Funding; Karyopharm: Consultancy. Fromm:Merck: Research Funding. Cowan:Abbvie: Research Funding; Bristol Myers Squibb: Research Funding; Cellectar: Consultancy; Sanofi: Consultancy; Janssen: Consultancy, Research Funding. Shadman:Mustang Bio, Celgene, Pharmacyclics, Gilead, Genentech, Abbvie, TG therapeutics, Beigene, Astra Zeneca, Sunesis, Beigene: Research Funding; Abbvie, Genentech, Astra Zeneca, Sound Biologics , Pharmacyclics, Verastem, ADC therapeutics, Beigene, Cellectar, BMS, Morphosys and Atara Biotherapeutics: Consultancy. Shustov:Seattle Genetics: Research Funding. Till:Mustang: Patents & Royalties, Research Funding. Ujjani:MorphoSys: Consultancy; Genentech: Consultancy, Honoraria; Atara: Consultancy, Honoraria; Gilead/Kite: Consultancy, Research Funding; Verastem Oncology: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria, Research Funding. Gopal:IgM bio, BMS, merck: Research Funding; imab bio, takeda,astrazeneca,gilead: Research Funding; Seattle Genetics; Janssen; Takeda; IgM Bio; IMab Bio; BMS; Astra Zeneca; Merck; Gilead: Research Funding; Seattle Genetics; Janssen; IMab Bio; TG Therapeutics; Astra Zeneca; Merck; Gilead; ADC Therapeutics; Nurix; TG therapeutics, Cellectar; Actinium: Consultancy.

Introduction ABVD (doxorubicin, bleomycin, vinblastine, and dacarbazine) represents standard frontline therapy for classical Hodgkin lymphoma (CHL) in North America. Substituting brentuximab vedotin for bleomycin in this regimen demonstrated improved efficacy in advanced stage patients (pts) but also increased toxicity (Connors et al NEJM 2017). PD-1 inhibitors are highly active in relapsed/refractory CHL, and the first-line setting may represent the ideal time for incorporating PD1 inhibition given the relatively intact host immunity and juxtaposition of malignant cells with T cells in the tumor microenvironment. Methods This was a single arm pilot study combining pembrolizumab with AVD in untreated CHL of any stage. Eligibility requiredECOG 0-1, adequate organ function, and measurable disease. The trial intended to enroll 30 pts. AVD was given at standard doses on days 1 and 15 of a 28-day cycle. Pembrolizumab (200 mg IV) was given starting cycle 1 day 1 and every 21 days thereafter (cycle 1 day 22, cycle 2 day 15 etc.). The primary objective was to estimate the safety of delivering 2 cycles of APVD. The secondary objective was to estimate the FDG-PET2 negative (Deauville score 1-3) rate after 2 cycles of APVD. Exploratory objectives included overall and progression free survival, predictive capacity of PET2 after APVD, analysis of ctDNA as well as assessments of metabolic tumor volume. After PET2 response assessment, subjects could continue APVD for up to 6 total cycles as deemed appropriate for their stage/risk factors (including alternate systemic therapy or radiotherapy). Results All 30 subjects have enrolled and received at least 2 cycles of therapy. Median age was 32 years (range 18-69). Most pts had advanced stage (stage I n =1 (3%), stage II n=11 (37%), stage III n=7 (23%), stage IV n=11, (37%)). Thirteen (43%) pts had B symptoms at diagnosis and 5 (17%) had bulky disease. Among the 30 pts enrolled, 28 are evaluable for response (one pt declined interim-PET and further treatment and final patient will have PET2 shortly after abstract deadline.Nineteen (68%) pts were PET2 neg (5PS 1-3). No PET2+ pts have progressed to date. End of therapy (EOT) PET negativity (after 2-6 cycles) was 78% (18/23). Among the 5 pts with residual FDG uptake at EOT, only 1 (20%) has developed recurrent lymphoma. With median follow-up of 10.3 months, 1-year PFS and OS were 96% and 100%, respectively. Six (20%) pts required interruption of pembrolizumab due to toxicity, primarily grade ≥ 2 transaminitis (83%). Those with grade 2 transaminitis (2/6) completed chemotherapy prior to resolving to grade 1 and did not receive additional pembrolizumab. Those with grade ≥ 3 transaminitis (3/6) were required to permanently discontinue pembrolizumab. All transaminitis was transient and resolved with steroids and/or withholding pembrolizumab. No pneumonitis and no other grade ≥ 3 immune-related AEs were observed. Toxicities were otherwise similar to those expected with ABVD chemotherapy. No pt had a treatment delay of > 21 days during the first 2 cycles, and no pt who interrupted pembrolizumab due to toxicity has relapsed. Updated efficacy and more detailed safety data will be presented at the meeting. Conclusion Pembrolizumab + AVD without a PD-1 lead-in is safe and effective therapy for frontline HL. In this study, PET2+ following APVD does not appear to be associated with high risk of disease relapse. Additional analyses of MTV and ctDNA are ongoing to better understand these results. Concurrent APVD, without an anti-PD-1 run-in, represents a well-tolerated, and efficacious backbone that can be further evaluated in all stages of CHL. Figure 1 Figure 1. Disclosures Lynch: Incyte: Research Funding; TG Therapeutics: Research Funding; Cyteir: Research Funding; Genentech: Research Funding; SeaGen: Research Funding; Bayer: Research Funding; Juno Therapetics: Research Funding; Morphosys: Consultancy. Ujjani: ACDT: Honoraria; Kite, a Gilead Company: Honoraria; Gilead: Honoraria; TG Therapeutics: Honoraria; Janssen: Consultancy; Epizyme: Consultancy, Membership on an entity's Board of Directors or advisory committees; Atara Bio: Consultancy; Loxo: Research Funding; Adaptive Biotechnologies: Research Funding; AstraZeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Consultancy, Research Funding; Pharmacyclics: Consultancy, Research Funding. Poh: Acrotech: Honoraria; Incyte: Research Funding; Morphosys: Consultancy. Smith: Incyte Corporation: Research Funding; Merck Sharp & Dohme Corp: Research Funding; Ignyta (spouse): Research Funding; Acerta Pharma BV: Research Funding; Portola Pharmaceuticals: Research Funding; ADC Therapeutics: Consultancy; Karyopharm: Consultancy; Ayala (spouse): Research Funding; De Novo Biopharma: Research Funding; KITE pharm: Consultancy; Genentech: Research Funding; AstraZeneca: Consultancy, Research Funding; Bristol Myers Squibb (spouse): Research Funding; Incyte: Consultancy; Bayer: Research Funding; Beigene: Consultancy, Research Funding; Millenium/Takeda: Consultancy. Shadman: Mustang Bio, Celgene, Bristol Myers Squibb, Pharmacyclics, Gilead, Genentech, Abbvie, TG Therapeutics, Beigene, AstraZeneca, Sunesis, Atara Biotherapeutics, GenMab: Research Funding; Abbvie, Genentech, AstraZeneca, Sound Biologics, Pharmacyclics, Beigene, Bristol Myers Squibb, Morphosys, TG Therapeutics, Innate Pharma, Kite Pharma, Adaptive Biotechnologies, Epizyme, Eli Lilly, Adaptimmune , Mustang Bio and Atara Biotherapeutics: Consultancy. Shustov: Seagen Inc.: Research Funding. Till: Mustang Bio: Consultancy, Patents & Royalties, Research Funding. Alizadeh: Gilead: Consultancy; Janssen Oncology: Honoraria; Roche: Consultancy, Honoraria; Celgene: Consultancy, Research Funding; Foresight Diagnostics: Consultancy, Current holder of individual stocks in a privately-held company, Current holder of stock options in a privately-held company; Bristol Myers Squibb: Research Funding; Forty Seven: Current holder of individual stocks in a privately-held company, Current holder of stock options in a privately-held company; CAPP Medical: Current holder of individual stocks in a privately-held company, Current holder of stock options in a privately-held company; Cibermed: Consultancy, Current holder of individual stocks in a privately-held company, Current holder of stock options in a privately-held company. Gopal: Epizyme: Consultancy, Honoraria; MorphoSys: Honoraria; Gilead: Consultancy, Honoraria, Research Funding; I-Mab bio: Consultancy, Honoraria, Research Funding; Genetech: Consultancy, Honoraria, Research Funding; Teva: Research Funding; Beigene: Consultancy, Honoraria; SeaGen: Consultancy, Honoraria, Research Funding; Incyte: Honoraria; Acrotech: Consultancy, Honoraria; Cellectar: Consultancy, Honoraria; Nurix Inc: Consultancy, Honoraria; ADC Therapeutics: Consultancy, Honoraria; Servier: Consultancy, Honoraria; Merck: Consultancy, Honoraria, Research Funding; Takeda: Research Funding; Astra-Zeneca: Research Funding; Agios: Research Funding; Bristol Meyers Squibb: Research Funding; Karyopharm: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Research Funding; IGM Biosciences: Research Funding; Kite: Consultancy, Honoraria.

Endogenous DNA damage is causally associated with the functional decline and transformation of stem cells that characterize aging. DNA lesions that have escaped DNA repair can induce replication stress and genomic breaks that induce senescence and apoptosis. It is not clear how stem and proliferating cells cope with accumulating endogenous DNA lesions and how these ultimately affect the physiology of cells and tissues. Here we have addressed these questions by investigating the hematopoietic system of mice deficient for Rev1, a core factor in DNA translesion synthesis (TLS), the postreplicative bypass of damaged nucleotides. Rev1 hematopoietic stem and progenitor cells displayed compromised proliferation, and replication stress that could be rescued with an antioxidant. The additional disruption of Xpc, essential for global-genome nucleotide excision repair (ggNER) of helix-distorting nucleotide lesions, resulted in the perinatal loss of hematopoietic stem cells, progressive loss of bone marrow, and fatal aplastic anemia between 3 and 4 months of age. This was associated with replication stress, genomic breaks, DNA damage signaling, senescence, and apoptosis in bone marrow. Surprisingly, the collapse of the Rev1Xpc bone marrow was associated with progressive mitochondrial dysfunction and consequent exacerbation of oxidative stress. These data reveal that, to protect its genomic and functional integrity, the hematopoietic system critically depends on the combined activities of repair and replication of helix-distorting oxidative nucleotide lesions by ggNER and Rev1-dependent TLS, respectively. The error-prone nature of TLS may provide mechanistic understanding of the accumulation of mutations in the hematopoietic system upon aging.

Background: Rituximab with cyclophosphamide, doxorubicin, vincristine, and prednisone (RCHOP) remains standard therapy for previously untreated diffuse large B-cell lymphoma (DLBCL). We previously reported that adding pembrolizumab to RCHOP (PR-CHOP), shows no significant additive toxicity and a promising 2-year progression free survival of 83% (Smith B J Haem 2019), with no progression events among 19 pts with known PDL-1+ tumors. In that analysis, we noted 83% of patients had tumor PDL-1 expression by IHC using a centralized standard assay, including 18/23 (78%) and 13/23 (56%) demonstrating positivity in ≥5% and ≥30% of lymphoma cells respectively. Herein we report long-term clinical follow up, as well as results of high-resolution molecular karyotyping using chromosome genomic array testing (CGAT), to assess whether 9p24.1 abnormalities explained the extent of PDL1 tumor expression. Methods: Pts age 18 years or older with previously untreated DLBCL, transformed lymphoma and grade 3 B follicular lymphoma eligible for 6-cycle, curative-intent RCHOP were eligible. Steroids within 7 days of treatment, active autoimmune disease, or history of pneumonitis were excluded. This phase I study combined pembrolizumab (200 mg IV q 3 weeks x 6) to RCHOP x 6, with supportive care per standard practice. There was no maintenance or consolidation therapy. Baseline PDL1 expression was analyzed centrally (Merck/Qualtek). CGAT was performed from DNA extracted from formalin-fixed, paraffin-embedded tissue sections using the OncoScan platform (ThermoFisher). H&E slides of adjacent sections of the tissue used for CGAT were evaluated by a pathologist to ensure a minimum of 30% tumor content. Patients were followed for relapse and survival. Results: Among 30 treated pts with a median follow up of 32 months, there have been no additional DLBCL relapses or deaths since the published report. There has been one relapse of follicular lymphoma in a patient with initial composite lymphoma , who is now in remission 1 year after autologous stem cell transplantation. 3-year estimated PFS is 83% and OS is 86%. On univariate analysis, only tumor bulk 7.5 cm or greater (p=.02) and absence tumor PDL-1 expression by IHC (p=.001) predicted inferior PFS. Tumor bulk, (p=.03), IPI 3 or higher (p=.01), and absence of tumor PDL-1 expression (p=.001) predicted worse overall survival. PFS and OS were unaffected by cell of origin by IHC, double expresser status, or diagnosis to treatment interval greater than median (29 days). Regarding safety, there were late cases of paraneoplastic pemphigus and rheumatoid arthritis 5 and 8 months from last dose of pembrolizumab, respectively. Both of these were managed successfully with immunosuppression. Chromosome genomic array testing CGAT) was performed to assess copy number aberrations (CNAs) and copy neutral loss of heterozygosity (cnLOH), particularly for the presence of gains or amplifications involving locus 9p24.1, containing the CD274 (PDL1) gene. Of 15 tested pretreatment baseline diagnostic tissue specimens, 14 provided informative result with 12 abnormal and 2 normal. Notably, no gain or amplification in 9p24.1 were seen; there was one case of deletion and 1 with cnLOH. The percent genome altered among abnormal cases ranged from 2% to 37% (median 12%). Complex karyotype, defined as genomic aberrations involving at least 3 chromosome arms (or % genome altered greater than 5% by CGAT), was seen in 10/14 pts (71%). This 14-sample data set included 6/14 pts with >30% PDL1 tumor expression (and 10 with 5% or greater PDL1-tumor expression). Conclusions: No additional safety signals have been observed, and PFS/OS remain favorable for the combination of pembrolizumab + RCHOP in this single arm trial with the best results in PDL-1+ disease. Despite frequent tumor PDL1-expression at baseline, no gains or implications of 9p24.1 were observed suggesting alternative mechanisms for overexpression of PDL-1. Further study this regimen and others testing combinations of immune checkpoint inhibition with first-line DLBCL therapy are warranted, to better ascertain the potential superiority of this strategy in this setting. Disclosures Smith: Portola: Research Funding; Incyte: Research Funding; Ignyta: Research Funding; Genentech: Research Funding; AstraZeneca: Research Funding; Acerta Pharma BV: Research Funding; Karyopharm: Consultancy; Beigene: Consultancy; Seattle Genetics: Research Funding; AstraZeneca: Consultancy; Millenium/Takeda: Consultancy; Pharmacyclics: Research Funding; Merck: Research Funding; De Novo Biopharma: Research Funding; Bayer: Research Funding; Ayala: Research Funding; Bristol Meyers Squibb: Research Funding. Fromm:Merck: Research Funding. Till:Mustang: Patents & Royalties, Research Funding. Shadman:Mustang Bio, Celgene, Pharmacyclics, Gilead, Genentech, Abbvie, TG therapeutics, Beigene, Astra Zeneca, Sunesis, Beigene: Research Funding; Abbvie, Genentech, Astra Zeneca, Sound Biologics , Pharmacyclics, Verastem, ADC therapeutics, Beigene, Cellectar, BMS, Morphosys and Atara Biotherapeutics: Consultancy. Lynch:Bayer: Research Funding; Rhizen Pharmaceuticals: Research Funding; Incyte: Research Funding; TG Therapeutics: Research Funding; Takeda: Research Funding; Juno Therpeutics: Research Funding; MorphoSys: Consultancy; Genentech: Research Funding; Cyteir: Research Funding. Cowan:Janssen: Consultancy, Research Funding; Bristol Myers Squibb: Research Funding; Sanofi: Consultancy; Cellectar: Consultancy; Abbvie: Research Funding. Ujjani:Gilead/Kite: Consultancy, Research Funding; Atara: Consultancy, Honoraria; Genentech: Consultancy, Honoraria; MorphoSys: Consultancy; Verastem Oncology: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria, Research Funding. Shustov:Seattle Genetics: Research Funding. Cassaday:Vanda Pharmaceuticals: Research Funding; Seattle Genetics: Current Employment, Current equity holder in publicly-traded company; Merck: Research Funding; Pfizer: Honoraria, Research Funding; Amgen: Consultancy, Research Funding; Kite/Gilead: Consultancy, Research Funding. Gopal:Seattle Genetics; Janssen; Takeda; IgM Bio; IMab Bio; BMS; Astra Zeneca; Merck; Gilead: Research Funding; Seattle Genetics; Janssen; IMab Bio; TG Therapeutics; Astra Zeneca; Merck; Gilead; ADC Therapeutics; Nurix; TG therapeutics, Cellectar; Actinium: Consultancy; IgM bio, BMS, merck: Research Funding; imab bio, takeda,astrazeneca,gilead: Research Funding.

Background: Early intervention can reduce the rate of progression and improve overall survival (OS) in smouldering multiple myeloma (SMM) patients (pts) (1, 2). The most powerful predictor of prognosis in active MM is whether pts achieve minimal residual disease (MRD) negativity in bone marrow with treatment (3), however treating MRD relapse has not been evaluated in a randomized fashion. The REMNANT study will evaluate whether treating MRD relapse after first line (1.L) treatment prolongs progression free survival (PFS) and OS for MM pts versus treating relapse after 1.L. treatment at progressive disease (PD) (4). To establish a homogenous group of MRD negative pts after 1.L treatment including autologous stem cell transplantation (ASCT), pts are enrolled at diagnosis and treated with Norwegian standard of care (SOC) 1.L treatment. MRD negative pts will move on to the randomized part. Methods: The REMNANT study is an academic, multicenter, open-label, randomized phase II/III study of NDMM pts eligible for ASCT (see Figure 1). 391 pts across Norway will be included in the phase II part of the study and receive SOC 1.L treatment according to Norwegian national guidelines; VRd (V: 1,3 mg/m2 SC Days 1, 4, 8, 11; R: 25 mg PO Days 1-14; d: 20 mg PO Days 1, 2, 4, 5, 8, 9, 11, 12) for 4 pre-transplant induction and 4 post-transplant consolidation cycles (all 21-d cycles). After induction pts will undergo tandem or single ASCT, depending on toxicity and response to first ASCT. The primary endpoint of the phase 2 part of the study is the number of pts who achieve MRD negative (Euroflow NGF 10 -5) complete response (CR) 30-45 days post consolidation. Safety evaluations and pts-reported outcome assessment will be measured. Pts (176) achieving MRD negative CR will be randomly assigned in a 1:1 ratio to receive 2.L treatment at MRD reappearance (arm A) or at progressive disease (PD) as defined by the IMWG criteria (4) (arm B). Randomization will be stratified by R-ISS stage at diagnosis and single vs tandem ASCT. Pts in arm A will be followed with MRD assessment every 4 month and start 2.L treatment at loss of MRD negative CR. Pts in arm B will be followed up by standard criteria and start 2.L treatment at PD. Both arms will receive the same 2.L treatment; KdD (all 28-d cycles) (K: 70mg/m2 iv Days 1,8,15 d: 40 mg Days 1, 8, 15, 22 D: 1800 mg SC Days 1, 8, 15 during C 1-2, Days 1, 8 during cycle 3-6, Day 1 from cycle 7,). 2.L treatment will continue until disease progression, unacceptable AEs or patient withdrawal. In arm A MRD Euroflow will be assessed after 6 and 18 months of 2L therapy. In arm B MRD Euroflow will be assessed if >CR is achieved but not before 6 months of 2 L therapy, and again after 12 consecutive months. The co-primary endpoint is progression and death by any cause (PFS) and death by any cause alone (OS). Secondary endpoints includes TTNT and the proportion pf pts who achieve MRD negative CR during 2.L treatment in arm A and arm B, safety evaluations and pts-reported outcome. The trial is approved and will start enrollment Q3 2020. 1. Mateos MV, Hernandez MT, Giraldo P, de la Rubia J, de Arriba F, Corral LL, et al. Lenalidomide plus dexamethasone versus observation in patients with high-risk smouldering multiple myeloma (QuiRedex): long-term follow-up of a randomised, controlled, phase 3 trial. Lancet Oncol. 2016;17(8):1127-36. 2. Lonial S, Jacobus S, Fonseca R, Weiss M, Kumar S, Orlowski RZ, et al. Randomized trial of lenalidomide versus observation in smoldering multiple myeloma. 2020;38(11):1126-37. 3. Munshi NC, Avet-Loiseau H, Rawstron AC, Owen RG, Child JA, Thakurta A, et al. Association of Minimal Residual Disease With Superior Survival Outcomes in Patients With Multiple Myeloma: A Meta-analysis. JAMA Oncol. 2017;3(1):28-35.5. 4. Kumar S, Paiva B, Anderson KC, Durie B, Landgren O, Moreau P, et al. International Myeloma Working Group consensus criteria for response and minimal residual disease assessment in multiple myeloma. Lancet Oncol. 2016;17(8):e328-e46. Disclosures Schjesvold: Amgen, Celgene, Janssen, MSD, Novartis, Oncopeptides, Sanofi, SkyliteDX, Takeda: Honoraria; Celgene, Amgen, Janssen, Oncopeptides: Research Funding; Amgen, Celgene, Janssen, MSD, Novartis, Oncopeptides, Sanofi, Takeda: Consultancy. OffLabel Disclosure: Carfilzomib-dexamethason-daratumumab (KdD) as second line treatment

Introduction Concizumab, a humanized recombinant monoclonal antibody directed against the tissue factor pathway inhibitor, is under investigation as a subcutaneous prophylactic treatment for patients with hemophilia A or B (HA/HB) with and without inhibitors. In the concizumab phase 2 trials, treatment was well tolerated and a favorable safety profile was shown, with no deaths or thromboembolic events and no adverse events (AEs) leading to withdrawal. We describe the non-fatal thrombotic serious AEs (SAEs) that occurred during the pivotal phase 3 explorer7 (NCT04083781) and explorer8 (NCT04082429) concizumab trials and the risk mitigations incorporated in the explorer clinical trials. Methods The explorer7 and explorer8 trials were initiated in late 2019 to evaluate the efficacy and safety of concizumab prophylaxis in HA/HB patients with/without inhibitors, respectively. Concizumab was administered subcutaneously with a 1.0 mg/kg loading dose (concizumab-naïve patients only) and a maintenance dose of 0.25 mg/kg daily from the second day onwards. Results In March 2020, explorer7 and explorer8 were paused due to the occurrence of two arterial and three venous thrombotic SAEs in three patients with HA or HB with inhibitors. All three patients had thrombotic risk factors present at baseline and had used concomitant hemostatic medication on the day of, and in two cases in the days up to, event onset. Two of the patients were among those with the highest concizumab exposure measured during phase 3. Laboratory parameters in all three patients were as expected. Based on these analyses, risk mitigation plans were developed, including guidelines for the concomitant use of hemostatic agents in the management of bleeding episodes while on concizumab prophylaxis and updates to the concizumab dosing regimen. Conclusion Novo Nordisk has assessed all available data and defined risk mitigation strategies and changes to the explorer trial protocols. Disclosures Seremetis: Novo Nordisk Ins: Current Employment, Current equity holder in private company. Cepo:Novo Nordisk: Current Employment. Skovgaard Rasmussen:Novo Nordisk: Current Employment. Høyer Rose:Novo Nordisk A/S: Current Employment, Divested equity in a private or publicly-traded company in the past 24 months. Tamer:Novo Nordisk: Current Employment, Current equity holder in private company, Divested equity in a private or publicly-traded company in the past 24 months. Porstmann:Novo Nordisk Health Care A/G: Current Employment. Haaning:Novo Nordisk: Current Employment, Current equity holder in publicly-traded company.

Background Waldenström's Macroglobulinemia (WM) is a rare indolent lymphoma with an estimated 1,500 new cases diagnosed each year in the United States (US). Over the last decade, several treatments have been introduced into the WM therapeutics landscape including, bendamustine, bortezomib, and most recently oral Bruton's kinase inhibitor (ibrutinib). There is limited information in the adoption of these WM treatments in real-world clinical settings in the US. We describe the practice patterns and clinical outcomes of first-line (1L) treatment of WM in a nationwide cohort of Veterans. Methods Using Veteran Affairs electronic health records (EHR) data, we identified Veterans who were diagnosed and received 1L treatment for WM between January 2006 and December 2018 in the Veterans Health Administration (VHA). Human annotation of EHR clinical records confirmed the diagnosis and 1L treatment regimens. Patients with another cancer diagnosis or patients with documentation that 1L treatment was received outside the VHA were excluded. Eligible patients were followed until loss to follow-up, death, or the end of the study period (June 30, 2019). Patient demographics, disease characteristics, and treatment patterns were identified. Local polynomial regression model curves were generated to demonstrate treatment changes over time. Unadjusted progression-free survival (PFS) and the unadjusted overall survival (OS) are also provided. Results We identified 505 patients diagnosed with WM in VHA between January 2006 thru December 2018. Of these, 318 patients received 1L treatment, with a median time from diagnosis to 1L treatment of 1.2 months (95% confidence interval [CI]: 0.5-5 months). The median age of WM patients was 69.9 years (standard deviation [SD]: 9.4 years), with approximately 73% of WM patients ≥65 years old. Prior to 1L treatment, the median hemoglobin and platelets observed were similar across all treatment groups, regardless of first 1L treatment. However, the median immunoglobulin M (IgM) was substantially lower in patient's treated with ibrutinib (2,570 mg/dL [range: 422-9,001 mg/dL]) and single-agent rituximab (R), 2,855 mg/dL (range: 84-7,880 mg/dL) when compared to those treated with chlorambucil +/- rituximab (4,416 mg/dL [range: (9-8,130 mg/dL]) and bortezomib/dexamethasone +/- rituximab (BDR), 4,086 mg/dL (range: 16-9,944 mg/dL). MYD88 testing occurred in 40 (13%) of patients, with testing most frequently occurring in patients treated with bendamustine +/- rituximab (BR), ibrutinib, and BDR- likely reflecting increased adoption in later periods. Hepatitis C testing occurred in 61 (19%) of patients, with testing most frequently occurring in patients treated with dexamethasone, rituximab, and cyclophosphamide (DRC), BDR, and BR. Over the study observation period, 1L practice patterns shift significantly with increased adoption of BR, BDR and ibrutinib and de-adoption of chemotherapy (Figure 1). The median follow-up time for all patients was 44 months (range: 1-147 months), although a shorter median follow-up time was observed in patients treated with therapeutics in recent years, such as ibrutinib (18 months [range: 2-53 months]) and BR (23 months [range: 4-86 months]). The median unadjusted PFS for all WM patients was 44 months (95% CI: 37-58 months) and the median unadjusted overall survival (OS) was 94 months (95% CI: 82-117 months). Conclusions The introduction of numerous therapeutic options throughout the past decade has profoundly altered the treatment landscape for WM, suggesting a shift in 1L practices from chlorambucil to BDR, BR, and most recently ibrutinib which has been increasingly adopted, since its approval in 2015, especially in older patients, suggesting that it may provide an effective therapeutic option for patients who may not be able to tolerate more aggressive treatment regimens. Limitations of this study include the differences observed in follow-up time as well as the limited number of patients in some 1L treatment groups. Further research is required to establish the long-term benefits and potential treatment-related toxicities of WM treatments in real-world clinical settings. Disclosures Sauer: Roche: Research Funding; Genentech, Inc.: Research Funding; Pharmacyclics: Research Funding; AbbVie: Research Funding. Halwani:AbbVie: Research Funding; Takeda: Research Funding; Roche: Research Funding; Genentech, Inc.: Research Funding; Miragen: Research Funding; Immunedesign: Research Funding; Kyowa Hakko Kirin: Research Funding; Seattle Genetics: Research Funding; Amgen: Research Funding; Pharmacyclics: Research Funding; Bristol Myers Squibb: Research Funding.