ALBERT

Description: Introduction: Venous thromboembolism (VTE) is a significant adverse event in adults receiving pegaspargase (PEG) for acute lymphoblastic leukemia (ALL). PEG increases VTE risk by depletion of antithrombin III (AT). Heparin requires adequate AT for anticoagulation. Younger adults with T-cell ALL receiving prednisone may be particularly at risk. Retrospective series (most with L-asparaginase) suggest AT supplementation may decrease VTE, however prospective data in adults beyond induction is limited while the optimal dose of AT remains undefined and varies across series. We reviewed adults at our institution who received PEG for ALL to assess the incidence of VTE within our AT supplementation practice. Laboratory and cost data for AT repletion were also analyzed. Methods: Adults who received PEG for ALL between 11/2015 and 7/2018 were retrospectively identified. Institutional recommendations were to supplement AT if serum AT 〈 60% following PEG for at least the first 2 courses (induction/consolidation). AT levels were assessed twice weekly until normalized. AT supplementation following additional cycles was recommended for all patients receiving therapeutic anticoagulation. Pharmacists calculated the AT dose using a repletion factor of 80-120%, rounded to the nearest vial. After VTE, patients received therapeutic enoxaparin throughout all remaining PEG doses, with enoxaparin held only if platelets 〈 50,000/mcL or for procedures. After 3/2018, all patients receiving PEG also received enoxaparin prophylaxis when platelets 〉30,000/mcL. A retrospective analysis was done to assess the incidence of VTE. Secondary endpoints included an assessment of VTE risk factors, ability to achieve therapeutic AT levels with supplementation and to characterize drug therapy costs with AT supplementation. Results: Thirty-one patients (30 newly diagnosed, 1 in relapse) with ALL received ≥ 1 dose of PEG followed by AT supplementation. Seventeen of 31 patients were adolescent/young adults (AYA) and 13/31 had T cell ALL. Additional patient characteristics are summarized in table 1. The incidence of VTE was 19%, with 7 VTEs identified in 6 patients. Two patients developed CNS thrombosis (1 fatal), 1 had a pulmonary embolism, and the remainder were upper extremity VTE. Six of 7 VTE occurred during the first two courses at a mean of 66 days (range 6-225) following the first PEG dose. Patients with VTE had a median platelet count of 118/mcL (range 34-377) and a mean AT nadir of 53% (36-98) within 72 hours of VTE. Two of 7 events occurred despite enoxaparin prophylaxis. Five of 6 (83%) patients with VTE had T-ALL; which was more common in the VTE vs. no-VTE group (p = 0.01). The incidence of VTE within the T-ALL group was 38%. Patients with VTE were all AYA and were younger than those without VTE (median 31 vs. 42 years, p = 0.06). Patients with VTE received a higher mean PEG dose than patients without VTE (4589 vs. 3504 units, p 〈 0.0001), reflective of the more aggressive dosing in the AYA regimen. Six of 7 VTEs occurred during a course containing prednisone (p = 0.08 vs. dexamethasone). AT nadirs during cycles with VTE were similar to cycles without VTE. No clinically significant bleeding occurred. Characteristics of patients with VTE are summarized in table 2. Overall the mean time to AT nadir was 11 days. Therapeutic AT (〉 60%) following supplementation occurred 56% of the time. Most AT doses (89%) were calculated with a correction factor of 80-89%. The probability of obtaining a therapeutic AT increased when a higher repletion factor (〉 90%) was used (76% vs. 52%, p = 0.06). Patients received a mean of 1.9 (0-6) doses of AT per PEG dose, and a mean of 5.9 (1-21) AT doses throughout treatment. The mean AT supplementation cost per PEG dose was $11,663 with 186 doses administered ($3.22/unit). Conclusions: VTE occurred in 19% of patients receiving AT supplementation following PEG, with 2/7 events involving the CNS. The risk of VTE was greatest in younger adults with T-ALL receiving concurrent prednisone and higher doses of PEG. AT levels were low at the time of VTE in most patients, however nadirs were similar compared to courses not complicated by VTE. Routine or augmented VTE prophylaxis and a higher AT repletion goal (〉 90%) may further limit VTE risk but given the cost and patient inconvenience, prospective evaluation is needed to confirm the benefit. Disclosures Frey: Servier Consultancy: Consultancy; Novartis: Consultancy. Perl:Pfizer: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Consultancy; Actinium Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees; Arog: Consultancy; Astellas: Consultancy; NewLink Genetics: Membership on an entity's Board of Directors or advisory committees. Porter:Genentech: Other: Spouse employment; Novartis: Other: Advisory board, Patents & Royalties, Research Funding; Kite Pharma: Other: Advisory board.

Description: Background: High-dose PTCy has been shown to effectively reduce acute (a) and chronic (c) GVHD after MRD and MUD BMT and to enable the safe implementation of haplo BMT. However, GVHD-related risk factors and survival outcomes, the impact of donor type, and novel composite endpoints, such as cGVHD-free relapse-free survival (cGFRFS), have not been fully characterized in BMT with PTCy. Methods: We retrospectively analyzed 582 consecutive adult pts with advanced or poor-risk hematologic malignancies who received allogeneic BMT with PTCy at Johns Hopkins from 2002-2012. All pts received a T-cell replete bone marrow graft and PTCy (50 mg/kg/d IV) on D+3 and +4. Platforms consisted of: 1) myeloablative conditioning (MAC) with Busulfan/Fludarabine or Busulfan/Cy followed by MRD (n = 193; 33%) or MUD (n=119; 20%) allografting and PTCy as sole GVHD prophylaxis; or 2) nonmyeloablative (NMA) conditioning with Fludarabine/Cy/TBI followed by related haplo (n = 270; 46%) allografting and PTCy, mycophenolate mofetil D5-35, and tacrolimus D5-180. Results: The median follow up was 4 (range 0.3-11.4) years (y). The median pt age at time of BMT was 49 (range 18-66) in the MAC cohort and 54 (range 18-73) in the NMA cohort. On competing risk analysis, the D200 probability of grade II-IV aGVHD was 27% after haplo, 37% after MRD, and 50% after MUD BMT, and grade III-IV aGVHD was 4%, 11%, and 14% respectively. The 3-y probability of cGVHD was 12% after haplo, 8% after MRD, and 19% after MUD BMT. On multivariate analysis adjusted for age and original disease risk index (DRI), MRD and MUD BMT were associated with a statistically significantly higher risk of grade II-IV and grade III-IV aGVHD compared to haplo BMT (each p ≤ 0.001). Compared to haplo BMT, MUD, but not MRD, BMT was also associated with a significantly higher risk of cGVHD (p = 0.009). On multivariate analysis, female into male allografting was independently associated with a higher risk of cGVHD (p = 0.007), whereas age and CMV serostatus of the pt and donor were not statistically significantly associated with risks of acute or chronic GVHD. Pts with grade II-IV aGVHD or cGVHD had a lower probability of relapse, but a higher probability of nonrelapse mortality (NRM) at 3 y compared to pts without GVHD. Among pts with GVHD, an HCT-CI score ≥ 5 was associated with significantly inferior overall survival compared to lower HCT-CI scores. Although MAC matched BMT was associated with less relapse risk than NMA haplo BMT, the 3-y probabilities of NRM, DFS, and overall survival were comparable between the transplant platforms (Table). On multivariate analysis adjusted for pt age and DRI, there were no statistically significant differences in DFS, OS, or cGFRFS in MAC related or unrelated BMT compared to NMA haplo BMT. Conclusions: High-dose PTCy safely modulates acute and chronic GVHD across multiple BMT platforms. The apparently lower risk of aGVHD after NMA haplo BMT with PTCy likely reflects the reduced conditioning intensity and longer duration of immunosuppression utilized. Despite the limitations inherent to a retrospective analysis, these data suggest that key outcomes after BMT with PTCy are comparable across donor types and conditioning intensities. Notably, in all these settings, 3-y estimates of cGFRFS appeared to approach those of DFS. Thus, PTCy may minimize the late morbidity and mortality of cGVHD and allow earlier implementation of novel posttransplantation strategies for relapse prevention. TableOutcomes of BMT with PTCy3-y probabilitiesNMA HaploMAC MRD*MAC MUD*NRM141717DFS384144OS495856cGFRFS313533 * p = NS for all comparisons to haplo BMT on multivariate analysis Disclosures Off Label Use: High-dose posttransplantation cyclophosphamide.

Description: Background: Recent advances in NMA haplo BMT, including high-dose PTCy for GVHD prophylaxis, have expanded potentially curative treatment options for patients (pts) without a matched donor. The DRI (Blood 2012;120:905), based on disease type and status, was developed to stratify pt risk across histologies and conditioning regimens. The current study evaluated the newly refined DRI (Blood 2014;123:3664) in the largest series of NMA haplo BMT to date. Methods: We retrospectively analyzed the outcomes of 374 consecutive adult hematologic malignancy pts who received NMA related haplo BMT with PTCy at Johns Hopkins. Eligibility included ECOG PS ≤ 2, LVEF ≥ 35%, adequate pulmonary and renal function and absence of uncontrolled infection. All pts received fludarabine (30 mg/m2IV D -6 to -2), Cy (14.5 mg/kg IV D -6 and -5), TBI (200 cGy D -1) and T-cell replete bone marrow. GVHD prophylaxis consisted of high-dose PTCy (50 mg/kg IV D 3 and 4), mycophenolate mofetil and tacrolimus. Maintenance therapy (e.g., imatinib) after engraftment was permitted. The median age was 55 (range 18-75) at BMT, 132 (35%) pts were aged ≥ 60 and 71 (19%) had prior autologous BMT. Diagnoses were acute leukemia or lymphoblastic lymphoma (115 pts; 31%), MDS or MPN (36 pts; 10%), aggressive NHL (95 pts; 25%), Hodgkin lymphoma (36 pts; 10%), mantle cell lymphoma (29 pts; 8%) and indolent lymphoid cancers (63 pts; 17%). By the new DRI, disease risk was low in 72 pts (19%), intermediate (int) in 242 (65%), high in 50 (13%) and very (v) high in 10 (3%). Overall results: With a median follow-up of 3.4 (range 0.5-11.4) years (y) in surviving pts, 3-y probabilities of PFS and OS were 40 (95% CI 35-45)% and 50 (45-56)%, respectively. The probability of neutrophil recovery was 89% by D30 (median 17 d). By competing-risk analyses, the D180 probability of nonrelapse mortality (NRM) was 8 (95% CI 5-10)%, grade 2-4 acute GVHD was 32 (27-37)%, and grade 3-4 acute GVHD was 4 (2-6)%. The 2-y probability of chronic GVHD was 13 (10-17)%. Results by DRI: Among the 3 DRI risk groups (low, int, high/v high), there were no statistically significant differences in histology (lymphoid vs myeloid), HCT-CI risk category, median CD34+ graft dose or pt CMV serostatus. Median pt age was greater in the higher risk groups (P = 0.01). On unadjusted analyses of the new DRI, the probability of relapse by competing-risk differed clearly between the groups (P 〈 0.0001; Fig. A), with no statistically significant difference in NRM (P = 0.53). This was coupled with statistically significant differences in both PFS and OS. In low, int and high/v high risk groups, 3-y PFS estimates were 64%, 37% and 22%, respectively (P 〈 0.0001; Fig. B), and 3-y OS estimates were 69%, 49% and 34% (P = 0.0001). Furthermore, on multivariate analyses adjusted for age and year of BMT, the new DRI was independently associated with overall outcomes. Compared to low-risk pts, the HR for relapse was 3.0 (95% CI 1.8-5.2) for int risk pts (P = 0.0001) and 4.7 (2.6-8.5) for high/ v high risk pts (P 〈 0.0001). HRs for both PFS and OS were ≥ 2-fold greater for int and high/v high risk pts compared to low risk pts (each P ≤ 0.0002). On multivariate analyses, the original DRI (13% low risk, 68% int, 19% high/v high) was also independently associated with relapse, PFS and OS (each P ≤ 0.003). When stratified by DRI, survival outcomes with reduced-intensity, matched related or unrelated BMT (based on 614 pts from the original DRI study cohort; personal communication, P. Armand) and haplo BMT with PTCy appeared similar (Table). Conclusion: The DRI appears to effectively stratify and prognosticate pts undergoing NMA haplo BMT. When stratified by DRI, the efficacy and survival outcomes with NMA haplo BMT with PTCy appear comparable to those reported with matched BMT. Within this transplant platform, the results support the use of the DRI in outcome analyses and randomized clinical trials involving heterogeneous groups of pts. Figure 1 Figure 1. Table Survival Estimates by DRI 3-y PFS (%) 3-y OS (%) Original DRI Matched Haplo Matched Haplo Low 66 63 70 71 Intermediate 31 39 47 49 High / very high 15 25 25 38 Figure 2 Figure 2. Disclosures Off Label Use: High-dose posttransplantation cyclophosphamide.

Description: Background: Concerns have been raised whether immune checkpoint inhibitor therapy in the alloBMT setting will result in graft versus host disease (GvHD) and transplant related mortality (TRM). We report our experience with a variety of checkpoint inhibitors used before or after allogeneic bone marrow transplantation (alloBMT). Our series comprises patients who received T cell-replete hematopoietic stem cells from HLA-haploidentical or -matched donors and is limited to those treated with post-transplant cyclophosphamide (PTCy) as primary GvHD prophylaxis. Patient selection: We retrospectively reviewed the records of alloBMT recipients who received PTCy and received checkpoint inhibitor therapy before or after alloBMT. GvHD was assessed using the CIBMTR GVHD index. Results: Eleven patients received checkpoint inhibitor therapy prior to alloBMT: anti-PD-1: Nivolumab n=6, anti-CTLA4: Ipilimumab n=8 (3 patients received both nivolumab and ipilimumab). These patients received a median of 4 (range 1 - 18) cycles of therapy. The median interval from last checkpoint inhibitor treatment to day of transplant was 43 (range 18-302) days. All patients received nonmyeloablative conditioning; 6 received partially mismatched allografts (5 were HLA haploidentical). Four patients developed Grade II aGvHD: Three patients who had received partially mismatched allografts (haplo-2, 9/10 unrelated-1) experienced stage 3 cutaneous GvHD only; one patient who received a 10/10 unrelated donor allograft developed stage 3 cutaneous GvHD with stage 1 liver involvement. Three patients were on immunosuppression when GvHD developed, the fourth patient with cutaneous and liver GvHD had been taken off tacrolimus on day 68 due to concerns of graft failure. GvHD resolved with treatment in each case. None of these patients developed chronic GvHD and none have died [median follow-up of 0.66 (range 0.91 - 2.0) years post alloBMT]. Nine patients received checkpoint therapy following alloBMT: anti-PD-1: Pembrolizumab n = 1, Nivolumab n= 6, anti-CTLA4: Ipilimumab n= 3 (one patient received nivolumab and ipilimumab). Eight patients had received nonmyeloablative conditioning; 5 received haploidentical allografts. Six received treatment for relapse of their hematologic malignancy, 1 for relapsed pediatric sarcoma, and 2 for newly diagnosed lung cancer. The median time to initiation of checkpoint inhibitor therapy was 1.2 (range: 0.8 - 5.8) years post alloBMT. Patients received a median of 5 (range 1 - 24) cycles of therapy. There was 1 case of Grade II aGvHD; stage 3 cutaneous GvHD when DLI from a 10/10 matched unrelated donor was given for relapsed disease after ipilimumab. This resulted in GvHD which was not accompanied by the desired graft-vs-leukemia effect. There were no other cases of acute or chronic GvHD in this group. There were 4 tumor-related deaths: pediatric sarcoma (1), lung cancer (1), and AML (2). The median follow-up for this group is 2 years (range 0.85 - 8.0) post alloBMT. Conclusions: In this small series, the incidence and severity of GvHD seen in patients who received checkpoint inhibitors was similar to that seen in patients treated with PTCy as GvHD prophylaxis without checkpoint inhibitors. GvHD was seen in patients treated with checkpoint inhibitors prior to alloBMT, but was generally mild and readily controlled and there were no associated deaths. In patients treated with checkpoint inhibitors after alloBMT, the only case of GvHD occurred after the patient received DLI. We caution that use of checkpoint inhibitors in closer temporal proximity to transplant might well be associated with increased risk of GvHD or severity of GvHD. Disclosures Borrello: WindMIL Therapeutics: Equity Ownership, Patents & Royalties, Research Funding; Celgene: Honoraria, Research Funding, Speakers Bureau; BMS: Honoraria, Research Funding. Wagner-Johnston:Seattle Genetics: Research Funding. Smith:Celgene: Consultancy, Other: member of DSMB.

Description: In this How I Treat article, the authors describe their clinical approach to this rapidly available transplantation platform and address some of the key clinical questions associated with its use.

Description: Introduction: Older patients with high-risk myeloid malignancies are now eligible for either induction chemotherapy (IC) or novel treatment strategies including liposomal cytarabine and daunorubicin (Vyxeos) or hypomethylating agent (HMA)/venetoclax. Vyxeos and HMA/venetoclax may be associated with less early mortality, but no trials have demonstrated significantly less mortality compared to IC. In this context, we need a better tool to determine a patient's risk of early mortality by strategy in order to inform therapy selection for older patients. The current methods to assess a patient's fitness for IC are the Eastern Cooperative Oncology Group (ECOG) or Karnofsky Performance Status (KPS) assessments, clinician subjective evaluations [i.e. gestalt (CG)], and often age itself (〉75-80 years). None of these include objective measures of fitness. The Fried frailty phenotype (FP) uses both subjective (exhaustion and activity level) and objective measures (weight loss, gait speed, and grip strength) of frailty to categorize patients into fit, pre-frail, and frail. We hypothesized that FP would correlate with early mortality in this population and could be used to guide initial treatment selection. Methods: From September, 2018 to June, 2019 we prospectively enrolled 30 patients age 60 years or older with newly diagnosed, untreated acute myeloid leukemia (AML) or high-risk myelodysplastic syndrome (MDS) on an ongoing institutional review board approved clinical trial. We performed FP, CG, hematopoietic cell transplantation-comorbidity index (HCT-CI), and ECOG assessments on all patients prior to initiation of any therapy for their high grade myeloid disease. The primary endpoints were 60 and 100-day mortality. Results: Median patient age and follow up were 70.9 (range 61-82) years and 111 days, respectively. Patients had high-risk disease features as shown in Table 1, with the vast majority of AML patients being adverse risk by European Leukemia Network criteria and all MDS patients being high or very high-risk by the Revised International Prognostic Scoring System. The most common molecular mutations were TP53, ASXL1, RUNX1, IDH1/2, FLT3, and DNMT3A. IC consisting of either 7+3 or Vyxeos was used in 11 patients, HMA alone or in combination in 16, targeted therapy with enasidenib alone in 1, and best supportive care (BSC) in 2 (Table 1). Four patients who were frail by FP received IC (3 with Vyxeos). By FP assessments, 17% of patients were fit (score 0), 33% were pre-frail (score 1-2), and 50% were frail (score 3-5). In contrast, CG categorized 37% of patients as fit, 30% as pre-frail, and 33% as frail. Seven of 15 frail patients by FP were categorized as pre-frail or fit by CG. FP and ECOG scores also differed with 7 patients having low-risk ECOG scores of 0-1 and a high-risk FP of ≥3 (frail). For entire cohort, 60- and 100-day mortality rates were 15% and 25%, respectively. Frail patients by FP had 60-day and 100-day mortality rates of 32% and 51%, respectively, which was significantly worse than fit and pre-frail patients, all of whom were alive at 100 days (Figure 1/2, p=.016). Of the 6 out of 15 FP frail patients who died, 1 received a HMA alone, 3 HMA with venetoclax, and 2 BSC. In patients with ECOG scores of 0-1 or those categorized as fit by CG, 100-day mortalities were 8% and 10%, respectively. Mortality for patients with HCT-CI scores of 1-2 was unexpectedly higher (34% at both 60 days and 100 days) than for patients with higher risk HCT-CI scores ≥3 (13% and 29%, respectively). Conclusion: In newly diagnosed older patients with advanced myeloid neoplasms, being frail by FP was associated with increased 60 and 100-day mortality, owing to high mortality rates with HMA based therapies. While HCT-CI scores have been significantly associated with mortality after allogeneic transplantation, we observed that these scores were not linearly associated with survival or mortality in newly diagnosed AML and high/very-high risk MDS patients. By ECOG and CG, even the low risk groups contained patient deaths, suggesting that these standard metrics may not capture certain at-risk patients. CG tended to down grade frailty scores, categorizing patients as fitter than they were by FP. As such, FP may be a useful tool to predict early mortality. Further research is warranted to determine whether mortality differs by treatment within a given FP category, which may support the use of FP to select initial therapy. Disclosures Frey: Novartis: . Gill:Novartis: Research Funding; Tmunity Therapeutics: Research Funding; Carisma Therapeutics: Research Funding; Amphivena: Consultancy; Aro: Consultancy; Intellia: Consultancy; Sensei Bio: Consultancy; Carisma Therapeutics: Equity Ownership. Perl:Bayer: Research Funding; BioMed Valley Discoveries: Research Funding; FujiFilm: Research Funding; Novartis: Honoraria, Other: Advisory board, Non-financial support included travel costs for advisory board meetings as well as a medical writing company that assisted with manuscript preparation/submission and slide deck assembly for academic meeting presentations of the data., Research Funding; Jazz: Consultancy, Honoraria, Other: Non-financial support included travel costs for advisory board meetings.; NewLink Genetics: Consultancy, Honoraria, Other: Non-financial support included travel costs for advisory board meetings.; Takeda: Consultancy, Honoraria, Other: Non-financial support included travel costs for advisory board meetings.; Astellas: Consultancy, Honoraria, Other: Non-financial support included travel costs for advisory board meetings as well as a medical writing company that assisted with manuscript preparation/submission and slide deck assembly for academic meeting presentations of trial data., Research Funding; Agios: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Non-financial support included travel costs for advisory board meetings.; Daiichi Sankyo: Consultancy, Honoraria, Other, Research Funding; Arog: Consultancy, Other: Non-financial support included travel costs for advisory board meetings.; AbbVie: Consultancy, Honoraria, Other: Non-financial support included travel costs for advisory board meetings.; Actinium Pharmaceuticals: Consultancy, Honoraria, Other: Clinical Advisory Board member, Research Funding. Maillard:Genentech: Consultancy; Regeneron: Consultancy. Pratz:Millenium/Takeda: Research Funding; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Agios: Membership on an entity's Board of Directors or advisory committees, Research Funding; Astellas: Membership on an entity's Board of Directors or advisory committees, Research Funding. Porter:Kite: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding; Incyte: Membership on an entity's Board of Directors or advisory committees; Glenmark Pharm: Membership on an entity's Board of Directors or advisory committees; Immunovative: Membership on an entity's Board of Directors or advisory committees; American Board of Internal Medicine: Membership on an entity's Board of Directors or advisory committees; Wiley and Sons: Honoraria; Genentech: Employment. Carroll:Astellas Pharmaceuticals: Research Funding; Incyte: Research Funding; Janssen Pharmaceuticals: Consultancy. Luger:Seattle Genetics: Research Funding; Biosight: Research Funding; Ariad: Research Funding; Agios: Honoraria; Genetech: Research Funding; Daichi Sankyo: Honoraria; Onconova: Research Funding; Kura: Research Funding; Jazz: Honoraria; Celgene: Research Funding; Cyslacel: Research Funding; Pfizer: Honoraria.

Description: Background: Older age is associated with inferior outcomes after allogeneic hematopoietic stem cell transplantation (HSCT) for acute myeloid leukemia (AML). High risk genetic characteristics are common among older patients and linked to poor outcomes in the non-transplant setting. An enhanced understanding of genetic risk may thus provide a basis for improving transplant outcomes in these patients. We evaluated the impact of leukemia genetic characteristics at diagnosis on HSCT outcomes in a multi-center cohort of AML patients age 60 or older receiving HSCT in first complete remission (CR1). Methods: We performed targeted sequencing of 112 genes on diagnostic leukemia samples from 257 patients with AML age 60 or older who received allogeneic HSCT in CR1 at 5 US transplant centers. Median age at diagnosis and HSCT were 65 (range 59-76) and 66 (range 60-76), respectively. 31% had clinically defined secondary AML, 11% had therapy-related AML, and 23% had adverse cytogenetics by 2017 ELN classification. Most (84%) were treated with anthracycline-based induction chemotherapy, while 16% received non-intensive induction. Conditioning was either reduced-intensity or non-myeloablative in 94% of patients. Median follow-up for survivors was 3.7 years; 3-year overall survival (OS) and leukemia-free survival (LFS) were 48% and 44%, respectively. Results: All patients had recurrent genetic alterations at the time of diagnosis, including 251 (98%) with gene mutations and 6 with only cytogenetic abnormalities. The most frequent gene mutations were DNMT3A (25%), NPM1 (23%), FLT3-ITD (22%), ASXL1 (21%), TET2 (21%), RUNX1 (20%), and SRSF2 (18%). Secondary-type mutations associated with antecedent MDS occurred in 42%, and 10% had TP53 mutations. As expected, secondary-type and TP53 mutations were associated with clinically-defined secondary AML (p

Description: Introduction: Grade 2-4 mucositis is a major complication after myeloablative (MAC) allogeneic hematopoietic transplantation (HCT) in about 90% of patients. Graft-vs-host-disease (GVHD) prophylaxis with methotrexate (MTX) exacerbates mucositis and delays engraftment. Severe mucositis precludes administration of all 4 MTX doses which increases the risk of GVHD and can prolong hospitalization due to infection, pain control, and the use of total parenteral nutrition (TPN). Leucovorin (LCV) prophylaxis following MTX is advised by the EBMT-ELN adult working group, but not universally accepted given the absence of prospective trials. Our group implemented routine LCV prophylaxis following MAC alloHCT with MTX GVHD prophylaxis in 8/2017. We compared the outcomes of these patients with historical controls. Methods: We treated 22 consecutive adults receiving MAC alloHCT with MTX GVHD prophylaxis with LCV 15 mg PO q6h x 4 doses, starting 12 h after the d +3, +6, and +11 MTX doses. Twenty-nine consecutive patients undergoing similar MAC conditioning and MTX GVHD prophylaxis were retrospectively identified as the control. Routine LCV was not given to control patients, but could have been added following d +6 or +11 MTX to limit toxicity at physician discretion. The primary endpoint was the incidence of grade 2-4 mucositis. Secondary endpoints included the duration of grade 2-4 mucositis, time to engraftment, incidence of neutropenic fever (NF) and bacteremia pre-engraftment, duration of antibacterials for NF, ability to receive all MTX doses, incidence and duration of TPN and patient-controlled analgesia (PCA) use, duration of hospitalization, incidence of acute and chronic GVHD, graft failure, and relapse. Results: Baseline characteristics between the two groups were similar (table 1). All patients received tacrolimus and MTX GVHD prophylaxis with the majority receiving Cy/TBI conditioning. Approximately 30% of controls received ≥ 1 dose of LCV (most following d +11 MTX) to limit toxicity. Although the incidence of grade 2-4 mucositis was similar with between groups (82% vs 91%, p = 0.38), a lower incidence of grade 3-4 mucositis was observed with LCV, although this did not reach statistical significance (32% vs. 55%, p = 0.16). The LCV group had a significantly shorter duration of grade 2-4 mucositis (5.6 vs. 9.7 d, p = 0.01) and less frequent PCA use (32% vs. 62%, p = 0.048). The LCV group needed TPN less often (18% vs. 38%, p = 0.21) and when needed, had a shorter duration of TPN (10 vs. 21 d, p = 0.15), although these findings did not reach statistical significance. The LCV group had a significantly shorter duration of hospitalization (28 d vs. 33.7 d, p = 0.03). Platelet engraftment seemed to be more rapid (16.5 vs 22.2 d, p = 0.097) without reaching statistical significance. The addition of LCV did not appear to impact the incidence of acute GVHD (grade 2-4: 23% vs. 14%, p = 0.47; grade 3-4 14 % vs 3%, p = 0.3) by d +100 or chronic GVHD at 1 year (14% vs. 21%, p = 0.44). No differences were observed in the time to neutrophil engraftment, or in the incidence of nephrotoxicity, hepatotoxicity, graft failure, or relapse between the arms. No other obvious practice change was implemented during the study period that would have been anticipated to impact any of these endpoints. Conclusions: The addition of LCV to MAC alloHCT with MTX GVHD prophylaxis resulted in significant reductions in the duration of grade 2-4 mucositis, frequency of PCA use, and duration of hospitalization compared to a similar historical control. We also observed less frequent grade 3-4 mucositis, more rapid platelet engraftment and less TPN use with LCV, but these findings did not reach statistical significance. Our sample size was small, which may have limited our power to detect small differences between the groups. In addition, about 30% of controls received at least 1 dose of LCV which could have biased our results toward the null. There was no increase in acute or chronic GVHD, graft failure, or relapse risk with the addition of LCV; however follow up remains relatively short. LCV prophylaxis following MTX GVHD prophylaxis warrants prospective evaluation to more definitely assess effects on mucositis, engraftment, GVHD and relapse, as well as to clearly determine the impact on resource utilization such as use of TPN, PCA, and length of hospitalization. Disclosures Frey: Novartis: Consultancy; Servier Consultancy: Consultancy. Gill:Extellia: Consultancy, Membership on an entity's Board of Directors or advisory committees; Carisma Therapeutics: Equity Ownership; Novartis: Research Funding. Perl:Pfizer: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Arog: Consultancy; Actinium Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Astellas: Consultancy; NewLink Genetics: Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Consultancy; AbbVie: Membership on an entity's Board of Directors or advisory committees. Stadtmauer:Celgene: Consultancy; Janssen: Consultancy; Amgen: Consultancy; Takeda: Consultancy. Porter:Novartis: Other: Advisory board, Patents & Royalties, Research Funding; Kite Pharma: Other: Advisory board; Genentech: Other: Spouse employment.

Description: Key Points Nonmyeloablative, related HLA-haploidentical BMT utilizing high-dose posttransplantation cyclophosphamide has a favorable safety profile. Risk-stratified relapse and survival outcomes with this approach are comparable to those of HLA-matched BMT.

Description: T cell-replete haploidentical donor transplants (HAPLO-HCT) using post-transplant cyclophosphamide for control of alloreactivity is now being increasingly utilized. HAPLO-HCTs were originally performed using BM grafts. However, recently, a few single center studies have reported good outcomes using G-CSF mobilized PBSC grafts for HAPLO-HCT. No prospective randomized comparisons of BM to PBSC grafts for HAPLO-HCT have been performed. Therefore, we analyzed outcomes for 687 adults (496 BM, 191 PBSC) who received HAPLO-HCT for hematologic malignancies using post-transplant cyclophosphamide + mycophenolate + calcineurin inhibitor for GVHD prophylaxis between 2009 and 2014 in the United States. The primary outcome was overall survival. The characteristics of recipients of BM and PBSC were similar except BM recipients were older, more likely to have a performance score ≥90, HCT-CI index ≤2, be CMV seronegative, have a lymphoid malignancy and receive reduced-intensity conditioning. Most PBSC transplants occurred between 2012 and 2014. The median follow-up was 35 and 20 months for recipients of BM and PBSC grafts, respectively. Cox regression models were built to study the effect of graft type adjusted for other significant factors on overall mortality, non-relapse mortality, relapse and graft-versus-host disease (GVHD) and outcomes censored at 2-years to accommodate differential follow-up between treatment groups (Table 1). After adjusting for age, CMV serostatus, disease risk index (disease type/disease status for myeloid and lymphoid malignancy and cytogenetic risk for acute leukemia and myelodysplastic syndrome) and transplant conditioning regimen there were no significant differences in risks for overall mortality (HR 1.00, p= 0.98; 2-year overall survival: 54% and 57%) or non-relapse mortality (HR 0.92, p=0.74; 2-year non-relapse mortality: 17% and 16%) after transplantation of BM compared to PBSC, respectively. However, relapse risks were higher after transplantation of BM compared to PBSC (HR 1.49, p=0.009; 2-year relapse: 45% and 28%). Subset analyses explored the effect of graft type separately for myeloablative and reduced intensity conditioning regimen adjusting for age, CMV serostatus and disease risk index. Consistent with the main analysis there were no differences in overall or non-relapse mortality risks and relapse risks were higher with BM compared to PBSC with myeloablative regimens (Table 1). Although this may in part be explained by lower chronic GVHD risks with transplantation of BM grafts, chronic GVHD was not significantly predictive of relapse risk when modeled as a time-dependent covariate (HR= 0.73, p=0.49). Grade II-IV acute GVHD risks (HR 0.45, p