Kansagra, Ankit

Abstract Introduction Proteasome inhibitors (PIs) and immunomodulatory drugs (IMiDs) have significantly improved survival in patients with multiple myeloma (MM). Refractoriness to PIs and IMiDs results in poor outcomes with a median survival of about 13 months.Daratumumab and isatuximab are CD38-targeting monoclonal antibodies (MoABs) with remarkable activity in relapsed and refractory MM. The outcome of MM patients in US clinical practice who becomes refractory to CD38 MoABs is unknown. The aim of this multicenter, retrospective study is to investigate the natural history of patients with MM who become refractory to CD38 MoABs (Monoclonal Antibodies in Multiple Myeloma: Outcomes after Therapy Failure: MAMMOTH study). Methods We identified patients from 14 academic institutions in the US with diagnosis of active MM and refractory to daratumumab or isatuximab, administered alone or in combination. Patients were considered refractory to CD38 MoAB if treated with at least 4 weeks of therapy and had evidence of progressive disease (PD) while on therapy or within 60 days after last dose. The time when patients met the above criteria of progression was defined as time zero (T0). Data including patient-disease characteristics and all therapies administered before and after T0 were collected with an electronic platform and submitted to peer-based quality check for completeness and internal consistency. For survival outcome analysis, patients were classified into three groups: "Penta-refractory" (refractory to 1 CD38 MoAB + 2 PIs + 2 IMiDs), "Triple-refractory and quad-refractory" (refractory to 1 CD38 MoAB + 1 PI + 1/2 IMiDs, or 1 CD38 MoAB + 1/2 PIs + 1 IMiD), and "Not triple-refractory" (refractory to 1 CD38 MoAB, and not both of a PI and an IMiD). Responses were evaluated using the IMWG criteria. Results Two hundred and seventy-five patients were included in this study; median age at T0 was 65 years (range 27-90). Fifty five percent of patients were males, 52% had IgG isotype, 29% had ISS stage III disease, and 29% had high-risk cytogenetics at diagnosis. Median interval from diagnosis of MM to T0 was 50.1 months (mo) (range 2.5-230.1). Patients received a median of 4 lines of treatment (1-16) prior to the CD38 MoAB-containing regimen; 72% underwent prior autologous transplant. Daratumumab-refractory patients formed a majority (256, 93.1%) of this cohort. Most of the patients were refractory to lenalidomide (77%), pomalidomide (65%), bortezomib (68%), and carfilzomib (47%). Seventy patients (25.5%) were "penta-refractory" and 148 (53.8%) were "triple-refractory and quad-refractory". Median follow-up from T0 for survivors was 10.6 mo (range 1.9-42.3 mo). The median overall survival (OS) from T0 for the entire cohort was 8.6 mo (95% C.I. 7.2-9.9); OS for the groups based on refractoriness to prior treatments are shown (Figure). Two hundred and forty-nine patients (90.5%) received at least one line of treatment after T0, (median 2, range 1-10). The response rates and depth of responses to each line of treatment post T0 are shown (Table). Among patients who received ≥ 1 subsequent treatment, the median PFS and OS from T0 were 3.4 (95% C.I. 2.8-4.0) mo and 9.3 (95% C.I. 8.1-10.6) mo, respectively; the median OS for the 26 patients who received no further treatment was only 1.3 (95% C.I. 0.6-1.9) mo. By multivariate analysis, penta-refractoriness (HR 2.4, p <0.001), high-risk cytogenetics (HR 1.5, p=0.01), elevated LDH (HR 2, p<0.001) and creatinine > 2 (HR 2.4, p=0.01) at the onset of CD38-based therapy predicted inferior OS. Conclusions Patients with MM who become refractory to CD38 MoAB are increasingly less responsive to subsequent therapies. While survival is particularly dismal for penta-refractory patients, the outcomes are poor even for patients who are not refractory to other mainstream MM agents. The MAMMOTH study defines a MM population in urgent need for new therapies, and provides benchmark OS, PFS and response data for subsequent investigational therapies in this setting. Disclosures Malek: Celgene: Consultancy, Speakers Bureau; Janssen: Consultancy, Speakers Bureau; Takeda: Consultancy, Speakers Bureau; Sanofi: Consultancy, Speakers Bureau; Amgen: Consultancy, Speakers Bureau. Paul:Bristol Myer Squibb: Other: Stock and pension plan (past employee). Neppalli:Amgen: Consultancy; Celgene: Consultancy. Liedtke:Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Prothena: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen/Onyx: Consultancy, Honoraria, Research Funding; BlueBirdBio: Research Funding; celgene: Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech/Roche: Research Funding; Caelum: Membership on an entity's Board of Directors or advisory committees. Hari:Amgen Inc.: Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Spectrum: Consultancy, Research Funding; Kite Pharma: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Research Funding; Sanofi: Honoraria, Research Funding; Janssen: Honoraria; Takeda: Consultancy, Honoraria, Research Funding. Vij:Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharma: Honoraria, Membership on an entity's Board of Directors or advisory committees; Jansson: Honoraria, Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees. Usmani:Abbvie, Amgen, Celgene, Genmab, Merck, MundiPharma, Janssen, Seattle Genetics: Consultancy; Amgen, BMS, Celgene, Janssen, Merck, Pharmacyclics,Sanofi, Seattle Genetics, Takeda: Research Funding. Kumar:Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding. Costa:Karyopharm: Research Funding; Sanofi: Honoraria; Janssen: Research Funding; BMS: Research Funding; Abbvie: Research Funding; Amgen: Honoraria, Research Funding; Celgene: Honoraria, Research Funding.

Background: Hematopoietic stem cell transplantation (HCT) remains the most effective postremission therapy for high-risk acute myeloid leukemia (AML). FMS-like tyrosine kinase3 (FLT3) mutations occur in about 30% of patients with cytogenetically normal AML. FLT3-ITD (internal tandem duplications) mutations are associated with short-lived remissions and poor outcomes. These adverse effects can be offset by allogeneic HCT in first complete remission (CR1). We carried out this study to get a real world perspective on feasibility of allogeneic HCT in CR1 for FLT3-ITD mutant AML patients. Methods: The Mayo Clinic AML database was queried for all patients that had tested positive for the FLT3 ITD, from January 2003 to December 2014. 75 patients were identified, of which 28 (37%) underwent allogeneic HCT in CR1. 12 were excluded as they were transplant ineligible from an age standpoint, 6 patients actually had MDS and 2 were excluded for primary induction failure. Clinical and outcomes data were abstracted retrospectively. Results: 29 patients were included in the final analysis, with a median age of 57 years (range 21-68), 38% males. Median time from diagnosis to last follow up was 339 days. 24(83%) had normal cytogenetics. 26(90%) received treatment with anthracycline + cytarabine based therapy, 3(10%) were enrolled on a clinical trial. 25(87%) patients went on to receive consolidation therapy. 22 (75%) of the patients relapsed after achieving a CR1, with a median time to relapse of 134 days (range 27-1710 days). Only 8 (26%) of the 22 patients were able to achieve a CR2 with salvage chemotherapy, of which 6 (75 %) successfully underwent allogeneic HCT.2 (25%) out of 8 patients received FLT3 inhibitor in 1st relapse. We then assessed the reasons why relapsed patients did not undergo HCT in CR1. The most common being; relapse during evaluation/work up for HCT in 8(27%) patients, 5 (17%) had comorbidities that precluded HCT, 3 (10%) were never referred for HCT due to personal preferences. At last follow up 19(65%) patients were dead. Conclusion: While allogeneic HCT is an effective consolidative strategy for FLT3 ITD mutant AML patients, in the real world, a large number are not transplanted in CR1 due to delays in donor search and transplant scheduling strategies resulting in disease relapse. Effective strategies to avoid delays in scheduling, rapid donor searches and the use of alternative donor sources are much needed for these patients. Figure 1 Figure 1. Figure 2 Figure 2. Disclosures No relevant conflicts of interest to declare.

Abstract Background: Acute graft versus host disease (aGVHD) is the leading cause of morbidity and mortality following allogenic hematopoietic cell transplantation (HCT). Corticosteroids are the first line treatment although <50% of patients with severe aGVHD (grades III-IV) achieve durable remissions. Monoclonal antibodies (mAb) are often used as second line agents for steroid refractory aGVHD (SR-aGVHD) (Patriarca et. al.; 2004). However, data regarding their tolerability and efficacy is retrospective and limited. We carried out this study to assess the clinical outcomes related to mAb therapy (Infliximab and Tocilizumab) for SR-aGVHD. Methods: Patients with SR-aGVHD that received therapy with either Infliximab or Tocilizumab between January 2003 and May 2016 were retrospectively identified. Clinical grading of aGVHD was per the Glucksberg criteria (Glucksberg et. al.; 1974). SR-aGVHD was defined as any grade progression within 3 days or failure to achieve at least one grade improvement within 7 days of initiation of systemic steroids. Infliximab and Tocilizumab were administered intravenously at 10mg/kg and 8mg/kg weekly for a total of 4 doses, respectively. Clinical response was evaluated at 4 weeks and 12 weeks post mAb treatment. Complete response (CR) was defined as sustained resolution of all clinical signs of aGVHD; partial response (PR) was defined as overall improvement of 1 or more grades; no response (NR) was defined as neither improvement nor worsening of the overall aGVHD grade. Overall response (OR) was defined as either CR or PR. Overall survival (OS) was calculated from the first day of mAb treatment until death or last available follow up. Results: Forty-three patients (median age 54, range 29-74 years; male 67%) with severe SR- aGVHD were included in the study. Of these, 35 (81%) received Infliximab for a median of 4 (range 1-6) cycles and 8 (19%) received Tocilizumab for a median of 3 (range 1-4) cycles. Both groups were comparable with regards to age, gender, conditioning regimen, graft source, degree of HLA match, ABO blood group, CMV incompatibility, and GVHD prophylaxis regimens. Only differences seen were a higher proportion of unrelated donor (p = 0.004) and cord blood HCT (p = 0.031) in the Tocilizumab group. Twenty (57%) of 35 patients treated with Infliximab and 6 (75%) of 8 patients treated with Tocilizumab had an overall aGVHD grade of IV prior to initiation of mAb therapy (p = 0.44). Organ specific distribution and severity of aGVHD are described in table 1. At 4 weeks post mAb therapy, 17 (40%) patients had an OR, 7 (16%) had no response, and 19 (44%) had died. Twenty-six (60%) patients died at 12 weeks, with OR and no response observed in 9 (21%) and 8 (19%) patients, respectively (table 2). Overall response for Tocilizumab versus Infliximab was comparable at 4 weeks (38% vs. 40%; p = 1.0) and at 12 weeks (38% vs. 17%; p = 0.33). Outcomes per aGVHD grade and gastrointestinal-specific stage at 4 weeks and 12 weeks are shown in figures 1-A and 1-B, with organ specific responses shown in figures 1-C and 1-D, respectively. The estimated median OS was 41 (range 4-3837) days for patients treated with Infliximab and 60 (range 10-756) days for those treated with Tocilizumab (p = 0.48). Disease relapse occurred in 5 (11%) patients treated with Infliximab and in none (0%) treated with Tocilizumab (p = 0.56). Thirty-four (79%) patients had infectious complications during and up to one month after mAb therapy. These included 31 (72%) patients with bacterial blood stream infection and 10 (23%) with invasive fungal infections. Overall, infectious complications were comparable (Infliximab - 83% vs. Tocilizumab - 63%; p = 0.33). CMV reactivation occurred in 11 (31%) and in 2 (25%) patients who were treated with Infliximab and Tocilizumab, respectively (p = 1.0). Given the retrospective nature of the study and the concomitant presence of aGVHD, it was difficult to attribute and grade gastrointestinal and hepatobiliary side effects. Conclusions: The use of anti-inflammatory monoclonal antibody therapy in patients with steroid refractory acute GVHD is associated with significant infectious complications (~80%) and poor response rates (~20% at 12 weeks). Current data, limited by a small sample size, does not show any advantages of using Tocilizumab over Infliximab or vice versa. Prospective clinical trials addressing this question are needed. Disclosures No relevant conflicts of interest to declare.

e18091 Background: Allogeneic HCT is a potentially curative option for certain patients with AML. However, in-hospital outcomes and cost haven't been described. We use the NIS, a nationally weighted sample of hospital discharges in the US, to examine these outcomes. Methods: Years 2002-2013 of the NIS were queried for adults with a primary diagnosis of AML undergoing HCT. Mortality, length of stay, hospital charges, and complications were analyzed and predictors of increased charges and mortality were determined with multivariate regression analysis. Results: From 2002-2013 19,965 adults with AML were admitted for HCT. Donor sources included peripheral blood stem cells (PBSCTs) (79%); bone marrow (BMTs) (15%); umbilical cord blood (6%). In hospital mortality was 8%. Major complications included stomatitis (36%), total parenteral nutrition (TPN) (17%), neutropenic fever (14%), bacteremia (12%), mechanical ventilation (6%), and dialysis (3%). Median charges per hospitalization increased (p<0.01) from $161,894 (2002) to $324,765 (2013); median length of stay (27 days) remained stable over time. Multivariable regressions are depicted (Table). Umbilical cord blood transplants were associated with increased mortality (OR 2.25, p<0.01) and charges ($69,105, p<0.01) relative to PBSCTs. Conclusions: This study demonstrates increasing cost of BMT on a national level as well as increased cost and mortality with umbilical cord transplants. [Table: see text]