Hefazi, Mehrdad

Abstract Chimeric antigen receptor T (CAR-T) cell therapy is a new pillar in cancer therapeutics; however, its application is limited by the associated toxicities. These include cytokine release syndrome (CRS) and neurotoxicity. Although the IL-6R antagonist tocilizumab is approved for treatment of CRS, there is no approved treatment of neurotoxicity associated with CD19-targeted CAR-T (CART19) cell therapy. Recent data suggest that monocytes and macrophages contribute to the development of CRS and neurotoxicity after CAR-T cell therapy. Therefore, we investigated neutralizing granulocyte-macrophage colony-stimulating factor (GM-CSF) as a potential strategy to manage CART19 cell–associated toxicities. In this study, we show that GM-CSF neutralization with lenzilumab does not inhibit CART19 cell function in vitro or in vivo. Moreover, CART19 cell proliferation was enhanced and durable control of leukemic disease was maintained better in patient-derived xenografts after GM-CSF neutralization with lenzilumab. In a patient acute lymphoblastic leukemia xenograft model of CRS and neuroinflammation (NI), GM-CSF neutralization resulted in a reduction of myeloid and T cell infiltration in the central nervous system and a significant reduction in NI and prevention of CRS. Finally, we generated GM-CSF–deficient CART19 cells through CRISPR/Cas9 disruption of GM-CSF during CAR-T cell manufacturing. These GM-CSFk/o CAR-T cells maintained normal functions and had enhanced antitumor activity in vivo, as well as improved overall survival, compared with CART19 cells. Together, these studies illuminate a novel approach to abrogate NI and CRS through GM-CSF neutralization, which may potentially enhance CAR-T cell function. Phase 2 studies with lenzilumab in combination with CART19 cell therapy are planned.

AbstractBackgroundScreening for vancomycin‐resistant Enterococcus (VRE) is performed at many transplant centers, but data on the impact of VRE colonization and bloodstream infection (BSI) on hematopoietic cell transplantation (HCT) outcomes remain conflicting.MethodsConsecutive adults with acute myeloid leukemia who underwent allogeneic HCT between 2004 and 2014 were retrospectively reviewed. Patients were screened by perirectal PCR swabs targeting vanA and vanB twice weekly while inpatient.ResultsOf a total of 203 patients (median age 54 years), 73 (36%) were VRE colonized prior to HCT, 23 (11%) became colonized within the first 100 days, and 107 (53%) remained non‐colonized through day 100 post HCT. A landmark analysis on HCT day 0 revealed no significant difference in overall survival according to pre‐transplant colonization status (P=.20). However, patients with subsequent VRE colonization within the first 100 days of HCT had a significantly worse survival on both univariable (P=.04) and multivariable (P=.03) analyses. During the first 30 days post HCT, 11 (5% of total and 11% of the VRE colonized) patients developed VRE BSI. Ten (91%) of these had screened positive for VRE colonization before the bacteremia. Age ≥60 years, HCT‐comorbidity index ≥3, and VRE colonization were independent risk factors for VRE BSI on multivariable analysis (P=.04, .03, .003, respectively). Only 1 (9%) patient with VRE BSI died within the first 100 days post HCT.ConclusionVRE colonization is a surrogate marker and not an independent predictor of worse outcomes post HCT. VRE BSI is associated with increased morbidity, but does not impact post‐HCT survival.

BACKGROUNDABO incompatibility is not a contraindication to hematopoietic cell transplantation (HCT), but it has been associated with additional risks including delayed engraftment, pure red cell aplasia (PRCA), and higher transfusion needs. Data on these events and on patient survival after reduced‐intensity conditioning (RIC) HCT are limited.STUDY DESIGN AND METHODSA total of 127 consecutive patients, 86 with acute myeloid leukemia and 41 with myelodysplastic syndromes, who underwent HLA‐matched peripheral blood RIC allogenic HCT between 2005 and 2014 were retrospectively analyzed.RESULTSEighty ABO‐compatible, 26 major/bidirectional, and 21 minor‐ABO‐mismatch HCT were identified. Compared to the ABO‐compatible group, major/bidirectional mismatches had increased red blood cell (RBC) transfusion requirement during the first 100 days (p = 0.009), delayed RBC and PLT engraftment (p = 0.0011 and p = 0.005, respectively), and higher incidence of grade II to IV acute graft‐versus‐host disease (aGVHD; p = 0.037). In multivariable analysis, major/bidirectional mismatches had significantly higher non‐relapse mortality (NRM) and inferior disease‐free survival (DFS) and overall survival (OS) compared with ABO‐compatible patients (p = 0.01, p = 0.04, and p = 0.035, respectively). Minor ABO mismatch had no impact on survival (p = 0.99). Four (15%) of 26 major/bidirectional mismatches developed PRCA. There was a significant association between fludarabine plus busulfan conditioning and PRCA (p = 0.0046).CONCLUSIONMajor/bidirectional ABO mismatch is associated with higher NRM and shortened DFS and OS in the setting of RIC HCT. Increased transfusion need, delayed RBC and platelet engraftment, PRCA, and increased severity of aGVHD are additional complications contributing to the morbidity.