Pulmonary complications post-hematopoietic stem cell transplantation (HSCT) such as diffuse alveolar hemorrhage (DAH) can occur in 2%-14% of HSCT patients with a mortality greater than 80%. [1][2][3][4] It is described as a syndrome of acute respiratory failure characterized by diffuse bilateral infiltrates and progressive hemorrhage and manifests as bleeding in the alveolar space due to injury to the alveolar-capillary basement membrane. 4,5 Clinical symptoms include cough, hypoxemia, and fever. [1][2][3][4] Imaging findings, either by x-ray or

Background Letermovir (LTM) was FDA-approved in 2017 for cytomegalovirus (CMV) prophylaxis in allogeneic hematopoietic cell transplant (HCT) patients. We evaluated the “real-world” impact of LTM in adult HCT recipients at the Mount Sinai Hospital in New York following addition of LTM to our formulary in June 2018. Methods In this retrospective study, we compared 31 consecutive allogeneic HCT recipients from June 2018-June 2019 who received LTM prophylaxis from Day +10–100 to 36 consecutive CMV-seropositive patients who underwent allogeneic HCT June 2017-June 2018 and did not receive LTM. Clinical and laboratory data were abstracted from the existing electronic medical record. The primary outcome was development of clinically significant CMV infection (CS-CMV) through 6 months post-HCT, defined as CMV viremia or disease requiring antiviral therapy. Results There were no baseline differences in patient demographics or transplant characteristics between patients who did and did not receive LTM prophylaxis. The median duration of LTM prophylaxis was 96 days (IQR, 66–116). At 6-months post-HCT, the cumulative incidence of CS-CMV was lower in patients receiving LTM prophylaxis vs no prophylaxis (29% vs 61%, respectively; p=0.004, Figure 1). Patients who received LTM developed CS-CMV at a later time post-HCT than those who did not receive prophylaxis (median 160 vs 39 days, respectively; p < 0.01). Among patients with CS-CMV, the median duration of antiviral therapy was 39 vs 70 days in the LTM prophylaxis vs no prophylaxis groups, respectively (p< 0.01). While there was no difference in the incidence of graft-versus-host disease (GVHD), the median time to GVHD diagnosis was longer in the LTM group (63 days vs 27 days in the no prophylaxis group; p=0.02). Between patients who did and did not receive LTM prophylaxis no statistically significant difference was observed, respectively, in incidence of CMV disease (3% vs 14%), hospital re-admission (68% vs 67%), or mortality (26% vs 14%) at 6 months post-HCT. Conclusion We demonstrated the “real-world” utility of LTM for CMV prevention in HCT recipients. Future studies should further evaluate the impact of LTM on antiviral drug usage, GVHD, and other transplant-related outcomes in this population. Disclosures All Authors: No reported disclosures

e19063 Background: Diffuse alveolar hemorrhage (DAH) is a life-threatening complication seen in patients with malignancy most commonly after a hematopoietic stem cell transplant (HSCT). Systemic therapy with corticosteroids to reduce inflammation and control bleeding is the mainstay of treatment for DAH, however ideal dosing strategies are not known. Methods: This single-center, retrospective study reviewed patients presenting to Roswell Park Comprehensive Cancer Center (RPCCC) from January 2010 through November 2022. Patients were included in this review if they were >18 years and were actively treated at RPCCC for presumed or definite DAH. The bone marrow transplant database, ICD-9, and ICD-10 codes were used to screen patients for inclusion. Upon meeting inclusion criteria, patients were stratified based on daily methylprednisolone dosing equivalents [low-dose: < 250 mg, intermediate-dose: >250 mg or < 1000 mg, high-dose: >1000 mg, or no steroid]. The primary endpoint was 30-day mortality. Secondary endpoints included ICU mortality, ICU length of stay (LOS), overall LOS, hemorrhage recurrence, steroid complications, and utilization of other DAH treatments. Steroid complications, including hyperglycemia, infection, and uremia were evaluated as safety endpoints. Results: Thirty-seven patients met inclusion criteria; 23 HSCT and 14 non-transplant patients. Analysis included 20 patients in the low-dose, 2 patients in the intermediate-dose, 12 patients in the high-dose, and 3 patients in the no steroid group. The median duration of steroids was 15, 4, and 14 days in the low, intermediate, and high groups, respectively. There was no statistically significant difference in 30-day mortality across treatment groups (p = 0.76). The overall 30-day mortality rate was 24.3%, with 25%, 50%, and 17% in the low, intermediate, and high-dose groups, respectively. A 30-day mortality rate of 33% was seen in patients who did not receive steroids. Hemorrhage recurrence occurred in 9 patients (24.3%), most commonly in the high-dose treatment group. Utilization of additional agents including aminocaproic acid, etanercept, and inhaled factor VIIa was most common in the intermediate-dose group. Conclusions: Despite variable steroid dosing, 30-day mortality was not found to be statistically significant among patients treated for DAH. Based on our findings of similar efficacy between dosing strategies, yet increased rates of steroid complications and hemorrhage recurrence in the high-dose group, lower steroid doses for the treatment of DAH can be considered. [Table: see text]

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