BCMA targeting chimeric antigen receptor (CAR) T cell therapy has shown deep and durable responses in multiple myeloma. However, relapse following therapy is frequently observed, and mechanisms of resistance remain ill-defined. Here, we perform single cell genomic characterization of longitudinal samples from a patient who relapsed after initial CAR T cell treatment with lack of response to retreatment. We report selection, following initial CAR T cell infusion, of a clone with biallelic loss of BCMA acquired by deletion of one allele and a mutation that creates an early stop codon on the second allele. This loss leads to lack of CAR T cell proliferation following the second infusion and is reflected by lack of soluble BCMA in patient serum. Our analysis suggests the need for careful detection of BCMA gene alterations in multiple myeloma cells from relapse following CAR T cell therapy.

Cardiopulmonary bypass induces an inflammatory state characterized by tumor necrosis factor-alpha release. Integrin CD11b is a neutrophil surface adhesive glycoprotein integrin that is rapidly and permanently unregulated by tumor necrosis factor-alpha exposure. The CD11b integrin is known to be the primary neutrophil integrin responsible for neutrophil lung and myocardial entrapment after cardiopulmonary bypass and subsequent reperfusion injury. Twenty-four adults admitted to the hospital for myocardial revascularization were equally randomized to one of three groups: group A (control), group B (methylprednisolone before cardiopulmonary bypass), and group C (low-dose aprotinin protocol). Blood was collected at three times: (1) baseline, (2) 50 minutes of cardiopulmonary bypass duration, and (3) 30 minutes after cardiopulmonary bypass termination. Neutrophil CD11b integrin expression was measured by fluorescence-activated cell sorter analysis and plasma tumor necrosis factor-alpha levels measured by enzyme-linked immunosorbent assay. Group A demonstrated significant (p < 0.05) increases in CD11b expression at times 2 and 3 when results were compared with those of the same group baseline and with those of groups B and C at similar times. No significant changes were noted between groups B and C at any time. Group A demonstrated a significant (p < 0.05) increase in levels of tumor necrosis factor-alpha at time 3 when results were compared with those of the same group baseline and of groups B and C at the same time. No significant changes were noted between B and C at any time. These results demonstrate low-dose aprotinin has a similar antiinflammatory effect to that of methylprednisolone in blunting cardiopulmonary bypass-induced systemic tumor necrosis factor-alpha release and neutrophil integrin CD11b upregulation.

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Background. Patients with advanced hematologic malignancies remain at risk for relapse following reducedintensity conditioning (RIC) allogeneic hematopoietic stem cell transplantation (allo-HSCT). We conducted a prospective clinical trial to test whether vaccination with whole leukemia cells early after transplantation facilitates the expansion of leukemia-reactive T cells and thereby enhances antitumor immunity. Methods. We enrolled 22 patients with advanced chronic lymphocytic leukemia (CLL), 18 of whom received up to 6 vaccines initiated between days 30 and 45 after transplantation. Each vaccine consisted of irradiated autologous tumor cells admixed with GM-CSF-secreting bystander cells. Serial patient PBMC samples following transplantation were collected, and the impact of vaccination on T cell activity was evaluated.Results. At a median follow-up of 2.9 (range, 1-4) years, the estimated 2-year progression-free and overall survival rates of vaccinated subjects were 82% (95% CI, 54%-94%) and 88% (95% CI, 59%-97%), respectively. Although vaccination only had a modest impact on recovering T cell numbers, CD8 + T cells from vaccinated patients consistently reacted against autologous tumor, but not alloantigen-bearing recipient cells with increased secretion of the effector cytokine IFN-γ, unlike T cells from nonvaccinated CLL patients undergoing allo-HSCT. Further analysis confirmed that 17% (range, 13%-33%) of CD8 + T cell clones isolated from 4 vaccinated patients by limiting dilution of bulk tumor-reactive T cells solely reacted against CLL-associated antigens. Conclusion.Our studies suggest that autologous tumor cell vaccination is an effective strategy to advance longterm leukemia control following allo-HSCT.Trial registration. Clinicaltrials.gov NCT00442130.

The predominant leukocyte population present in both human and murine peritoneal ovarian tumors is the Vascular Leukocyte (VLC). VLCs are recruited en masse to the ovarian tumor microenvironment whereupon they promote tumor progression. Importantly, the presence of VLCs is requisite for peritoneal ovarian cancer progression: selective elimination of VLCs inhibits tumor burden and ascites accumulation. Despite the critical importance of VLCs to ovarian tumors, their derivation and the mechanisms by which they facilitate tumor progression are not well understood.Here we demonstrate in vivo that the murine ID8 ovarian tumor model can usurp the host peritoneal macrophage pathway to elicit and recruit VLCs. Moreover, we demonstrate that VLCs express CD11b and Gr-1, a characteristic phenotype shared amongst heterogeneous populations of leukocytes referred to as myeloid-derived suppressor cells (MDSCs). In accord with their MDSC phenotype, both murine and human VLCs express arginase 1 (ARG1). Importantly, we demonstrate that the VLCs suppress both CD8 + and CD4 + T cells responses and that this immunosuppression is ARG1 -dependent, since blockade of VLC ARG1 activity with nor-NOHA reversed the immunosuppression. These data further characterize the tumor associated leukocytes in ovarian cancer and provide insights into the mechanisms by which they promote tumor growth.