The role of the immune microenvironment in maintaining disease remission in patients with multiple myeloma (MM) is not well understood. In this study, we comprehensively profile the immune system in patients with newly diagnosed MM receiving continuous lenalidomide maintenance therapy with the aim of discovering correlates of long-term treatment response. Leveraging single-cell RNA sequencing and T cell receptor β sequencing of the peripheral blood and CyTOF mass cytometry of the bone marrow, we longitudinally characterize the immune landscape in 23 patients before and one year after lenalidomide exposure. We compare patients achieving sustained minimal residual disease (MRD) negativity to patients who never achieved or were unable to maintain MRD negativity. We observe that the composition of the immune microenvironment in both the blood and the marrow varied substantially according to both MRD negative status and history of autologous stem cell transplant, supporting the hypothesis that the immune microenvironment influences the depth and duration of treatment response.

Factors contributing to hematopoietic recovery following chimeric antigen receptor (CAR) T-cell therapy have not been well studied. In an analysis of 83 patients with hematologic malignancies treated with CAR T-cell therapy, we describe patterns of hematopoietic recovery and evaluate potentially associated factors. We included patients who received axicabtagene ciloleucel (n = 30) or tisagenlecleucel (n = 10) for B-cell lymphoma, CD19-28z CAR T therapy for B-cell acute lymphoblastic leukemia (NCT01044069; n = 37), or B-cell maturation antigen targeting CAR T cells for multiple myeloma (NCT03070327; n = 6). Patients treated with CAR T cells who had not progressed, died, or received additional chemotherapy had "recovered" (per definition in Materials and methods section) hemoglobin, platelet, neutrophil, and white blood cell counts at rates of 61%, 51%, 33%, and 28% at month 1 postinfusion and 93%, 90%, 80%, and 59% at month 3 postinfusion, respectively. Univariate analysis showed that increasing grade of immune effector cell-associated neurological syndrome (ICANS), baseline cytopenias, CAR construct, and higher peak C-reactive protein or ferritin levels were statistically significantly associated with a lower likelihood of complete count recovery at 1 month; a similar trend was seen for cytokine release syndrome (CRS). After adjustment for baseline cytopenia and CAR construct, grade ≥3 CRS or ICANS remained significantly associated with the absence of complete count recovery at 1 month. Higher levels of vascular endothelial growth factor and macrophage-derived chemokines, although not statistically significant, were seen patients without complete count recovery at 1 month. This remains to be studied further in larger prospective studies.

Autologous stem cell transplantation (ASCT) remains the standard of care for transplantation-eligible patients with multiple myeloma (MM). Bortezomib with lenalidomide and dexamethasone (VRD) is the most common triplet regimen for newly diagnosed MM in the United States. Carfilzomib with lenalidomide and dexamethasone (KRD) has shown promising efficacy and may supplant VRD. We compared stem cell yields and autograft minimal residual disease (MRD)-negativity after VRD and KRD induction. Deeper responses (ie, very good partial response or better) were more common with KRD. Precollection bone marrow (BM) cellularity, interval from the end of induction therapy to start of stem cell collection, and method of stem cell mobilization were similar for the 2 cohorts. Days to complete collection was greater with KRD (2.2 days, versus 1.81 days with VRD), which more often required >= 3 days of apheresis. Precollection viable CD34(+) cell content was greater with VRD, as was collection yield (11.11 x 10(6), versus 9.19 x 10(6) with KRD). Collection failure (defined as <2 x 10(6) CD34(+) cells/kg) was more frequent with KRD (5.4% versus .7% with VRD). The difference in stem cell yield between VRD and KRD is associated with the degree of lenalidomide exposure. Age >= 70 years predicted poorer collection for both cohorts. Stem cell autograft purity/MRD-negativity was higher with KRD (81.4%, versus 57.1% with VRD). For both cohorts, MRD-negativity was attained in a larger fraction of autografts than in precollection BM. For patients proceeding to ASCT, the time to neutrophil/platelet engraftment was comparable in the 2 study arms. In summary, our data demonstrate that KRD induces deeper clinical responses and greater autograft purity than VRD without compromising stem cell yield or post-transplantation engraftment kinetics. (C) 2020 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.