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Anti-CD19 chimeric antigen receptor (CAR)-expressing T cells are an effective treatment for B-cell lymphoma, but often cause neurologic toxicity. We treated 20 patients with B-cell lymphoma on a phase I, first-in-human clinical trial of T cells expressing the new anti-CD19 CAR Hu19-CD828Z ( NCT02659943 ). The primary objective was to assess safety and feasibility of Hu19-CD828Z T-cell therapy. Secondary objectives included assessments of blood levels of CAR T cells, anti-lymphoma activity, second infusions and immunogenicity. All objectives were met. Fifty-five percent of patients who received Hu19-CD828Z T cells obtained complete remission. Hu19-CD828Z T cells had clinical anti-lymphoma activity similar to that of T cells expressing FMC63-28Z, an anti-CD19 CAR tested previously by our group, which contains murine binding domains and is used in axicabtagene ciloleucel. However, severe neurologic toxicity occurred in only 5% of patients who received Hu19-CD828Z T cells, whereas 50% of patients who received FMC63-28Z T cells experienced this degree of toxicity (P = 0.0017). T cells expressing Hu19-CD828Z released lower levels of cytokines than T cells expressing FMC63-28Z. Lower levels of cytokines were detected in blood from patients who received Hu19-CD828Z T cells than in blood from those who received FMC63-28Z T cells, which could explain the lower level of neurologic toxicity associated with Hu19-CD828Z. Levels of cytokines released by CAR-expressing T cells particularly depended on the hinge and transmembrane domains included in the CAR design. In a first-in-human, phase I trial in patients with B-cell lymphoma, CD19 CAR T cells with fully human binding domains exhibit lower neurologic toxicity, but similar clinical activity, to previously tested CD19 CAR T cells with murine binding domains.

Deuterated water (2H2O) is a label commonly used for safe quantitative measurement of deuterium enrichment into DNA of proliferating cells. More recently, it has been used for labeling proteins and other biomolecules. Our in vitro - in vivo research reports important stable isotopic labeling enrichment differences into the DNA nucleosides and their isotopologues (e.g. deoxyadenosine (dA) M + 1, dA M + 2, dA M + 3), as well as tumor cell proliferation effects for various forms of commercially available stable heavy water (2H2O, H218O, and 2H218O). Using an in vitro mouse thymus tumor cell line, we determined that H218O provides superior DNA labeling enrichment quantitation, as measured by GC-positive chemical ionization (PCI)-MS/MS. In addition, at higher but physiologically relevant doses, both 2H218O and 2H2O down modulated mouse thymus tumor cell proliferation, whereas H218O water had no observable effects on cell proliferation. The in vivo labeling studies, where normal mouse bone marrow cells (i.e. high turnover) were evaluated post labeling, demonstrated DNA enrichments concordant with measurements from the in vitro studies. Our research also reports a headspace-GC-NCI-MS method, which rapidly and quantitatively measures stable heavy water levels in total body water.

Background to hematopoietic cell transplantation, including post transplant immune recovery

The role of B cells in T-cell priming is unclear, and the effects of B-cell depletion on immune responses to cancer vaccines are unknown. Although results from some mouse models suggest that B cells may inhibit induction of T cell–dependent immunity by competing with antigen-presenting cells for antigens, skewing T helper response toward a T helper 2 profile and/or inducing T-cell tolerance1,2,3,4, results from others suggest that B cells are necessary for priming as well as generation of T-cell memory5,6,7. We assessed immune responses to a well-characterized idiotype vaccine in individuals with severe B-cell depletion but normal T cells after CD20-specific antibody–based chemotherapy of mantle cell lymphoma in first remission. Humoral antigen- and tumor-specific responses were detectable but delayed, and they correlated with peripheral blood B-cell recovery. In contrast, vigorous CD4+ and CD8+ antitumor type I T-cell cytokine responses were induced in most individuals in the absence of circulating B cells. Analysis of relapsing tumors showed no mutations or change in expression of target antigen to explain escape from therapy. These results show that severe B-cell depletion does not impair T-cell priming in humans. Based on these results, it is justifiable to administer vaccines in the setting of B-cell depletion; however, vaccine boosts after B-cell recovery may be necessary for optimal humoral responses.

Guidelines for preventing infectious complications among hematopoietic cell transplant recipients: a global perspective

Marrow stromal layers were used to investigate the potential role of negative regulators produced by the marrow microenvironment as one potential cause of hematopoietic suppression after chemotherapy and cytokines. Stromal layers were established from marrow of normal or prechemotherapy donors and breast cancer patients after hematological recovery from one cycle of 5-fluorouracil, leucovorin, doxorubicin, and cyclophosphamide and GM-CSF or PIXY321 (GM-CSF/IL-3 fusion protein). Normal donor CD34+ cells were placed in contact with stromal layers, and the number of colony-forming units for granulocytes and macrophages (CFU-GM) was determined. There were 25-79% fewer CFU-GM in post-chemotherapy stromal layer cocultures than in no chemotherapy cocultures. With neutralizing antibody to TNF-alpha the number of CFU-GM in no chemotherapy and post-chemotherapy stromal cocultures was, respectively, 96 +/- 7% (n = 5) and 142 +/- 8% (n = 5) of the number with no antibody treatment. PIXY321 and GM-CSF pretreated stromal layers also suppressed production of CFU-GM. Anti-TNF-alpha promoted an increase in CFU-GM numbers from GM-CSF, but not PIXY321, pretreated stromal cocultures. The results demonstrate that post-chemotherapy marrow stromal layers were deficient in supporting in vitro hematopoiesis and suggest that negative regulators induced by chemotherapy and cytokines may be one cause for this defect.

Vaccine based immunotherapy directed toward recently-defined tumor antigens represents a new approach for the treatment of neoplastic disease. Because minimal tumor burdens are most susceptible to such therapy, it is important to define how this approach could be used successfully in hosts immediately following debulking chemotherapy. Previously, we studied immune reconstitution in patients aged 1-24 years after intensive T cell depleting chemotherapy and found that thymic involution occurred in all patients studied immediately post-chemotherapy. For patients over 10 years of age, thymic inactivity persisted for at least 6 months after completion of chemotherapy. Hence, even relatively young patients appear dependent upon thymic-independent pathways of T cell regeneration for a prolonged period post-chemotherapy. Using thymectomized mice, we now have studied thymic-independent pathways of T cell regeneration after in vivo T cell depletion. We report that thymic-independent T cell regeneration primarily involves expansion of peripheral T cell populations and requires T cell-MHC interactions since CD8 expansion did not occur in β2m-/- mice (which lack MHC Class I) and CD4 expansion was diminished in mice treated with MHC Class II-blocking antibodies. When CD4 and CD8 T cells bearing transgenic T cell receptors (TCRs) were used as T cell inocula, expansion occurred only when antigen specific for the transgenic TCR was supplied. These results provide evidence that thymic-independent T cell regeneration occurs primarily via antigen-driven expansion of peripheral T cell populations. Such antigen-driven expansion of T cells bearing transgenic TCRs resulted in a marked skewing of the regenerated T cell repertoire toward the particular target antigens with approximately 40% of the regenerated CD4 or CD8 T cells expressing an antigen-specific TCR. Thus, when a T cell inoculum containing appropriate TCR specificities is supplied in combination with the target antigen during a period of T cell regeneration in thymic-deficient hosts, significant skewing of the T cell repertoire toward a particular target antigen can occur. We are using such an approach as the basis for a clinical trial of vaccine-driven expansion of antigen-specific T cells directed toward tumor-specific proteins expressed by Ewing's sarcoma and alveolar rhabdomyosarcoma which will follow a debulking phase of intensive cytotoxic chemotherapy.

Cell–cell adhesion is essential for many immunological functions1–4, including interaction of cytotoxic T lymphocytes (CTLs) with their targets5–8. We have explored CTL-target interactions using well-characterized cloned human CTLs9,10. Conjugate formation between these CTLs and many antigen-negative targets is almost as efficient as with specific target cells, but does not lead to target-cell lysis. Thus, on specific target cells, adhesion by antigen-independent pathways may occur concurrently with or precede antigen recognition. The molecules LFA-1, CD2 (Til, LFA-2) and LFA-3 have been shown11–15 to be involved in human CTL conjugation with and lysis of specific target cells. Here we describe monoclonal antibody inhibition studies using individual monoclonal antibodies and mixes which demonstrate (1) that LFA-1, CD2 and LFA-3 are involved in antigen-independent conjugate formation; and (2) suggest that CD2 and LFA-3 are involved in one pathway and LFA-1 in another. We confirmed the existence of distinct pathways by the demonstration that LFA-1-dependent adhesion requires divalent cations and is temperature-sensitive whereas CD2- and LFA-3-dependent adhesion does not require divalent cations and is temperature-insensitive. Together with previous data, our studies suggest that CD2 on the effector interacts with LFA-3 as its ligand on targets.