Preclinical evaluation of CD8+ anti-BCMA mRNA CAR T cells for treatment of multiple myeloma.

Chimeric antigen receptor (CAR) T-cell therapy remains limited to select centers that can carefully monitor adverse events. To broaden use of CAR T cells in community clinics and in a frontline setting, we developed a novel CD8+ CAR T-cell product, Descartes-08, with predictable pharmacokinetics for treatment of multiple myeloma. Descartes-08 is engineered by mRNA transfection to express anti-BCMA CAR for a defined length of time. Descartes-08 expresses anti-BCMA CAR for 1 week, limiting risk of uncontrolled proliferation; produce inflammatory cytokines in response to myeloma target cells; and are highly cytolytic against myeloma cells regardless of the presence of myeloma-protecting bone marrow stromal cells, exogenous a proliferation-inducing ligand, or drug resistance including IMiDs. The magnitude of cytolysis correlates with anti-BCMA CAR expression duration, indicating a temporal limit in activity. In the mouse model of aggressive disseminated human myeloma, Descartes-08 induces BCMA CAR-specific myeloma growth inhibition and significantly prolongs host survival (p < 0.0001). These preclinical data, coupled with an ongoing clinical trial of Descartes-08 in relapsed/refractory myeloma (NCT03448978) showing preliminary durable responses and a favorable therapeutic index, have provided the framework for a recently initiated trial of an optimized/humanized version of Descartes-08 (i.e., Descartes-11) in newly diagnosed myeloma patients with residual disease after induction therapy.

Preclinical Activity of JNJ-7957, a Novel BCMA×CD3 Bispecific Antibody for the Treatment of Multiple Myeloma, Is Potentiated by Daratumumab.

PURPOSE: Multiple myeloma (MM) patients with disease refractory to all available drugs have a poor outcome, indicating the need for new agents with novel mechanisms of action. EXPERIMENTAL DESIGN: We evaluated the anti-MM activity of the fully human BCMA×CD3 bispecific antibody JNJ-7957 in cell lines and bone marrow (BM) samples. The impact of several tumor- and host-related factors on sensitivity to JNJ-7957 therapy was also evaluated. RESULTS: We show that JNJ-7957 has potent activity against 4 MM cell lines, against tumor cells in 48 of 49 BM samples obtained from MM patients, and in 5 of 6 BM samples obtained from primary plasma cell leukemia patients. JNJ-7957 activity was significantly enhanced in patients with prior daratumumab treatment, which was partially due to enhanced killing capacity of daratumumab-exposed effector cells. BCMA expression did not affect activity of JNJ-7957. High T-cell frequencies and high effector:target ratios were associated with improved JNJ-7957-mediated lysis of MM cells. The PD-1/PD-L1 axis had a modest negative impact on JNJ-7957 activity against tumor cells from daratumumab-naïve MM patients. Soluble BCMA impaired the ability of JNJ-7957 to kill MM cells, although higher concentrations were able to overcome this negative effect. CONCLUSIONS: JNJ-7957 effectively kills MM cells ex vivo, including those from heavily pretreated MM patients, whereby several components of the immunosuppressive BM microenvironment had only modest effects on its killing capacity. Our findings support the ongoing trial with JNJ-7957 as single agent and provide the preclinical rationale for evaluating JNJ-7957 in combination with daratumumab in MM.

TACI-Ig induces immune balance of Th cells in MLN via BLyS/APRIL-receptors signaling in rats with adjuvant-induced arthritis.

The transmembrane activator and calcium modulator and cyclophilin ligand interactor-immunoglobulin (TACI-Ig), a recombinant fusion protein that modulates B and T cells activation by binding and neutralizing B lymphocyte stimulator (BLyS) and a proliferation-inducing ligand (APRIL), has been shown to have a therapeutic effects on autoimmune disorders. The objective of this study was to investigate immunoregulatory efficacy of TACI-Ig on helper T (Th) cells in mesenteric lymph node (MLN) of adjuvant-induced arthritis (AA) in rats. The levels of BLyS, APRIL, interferon (IFN)-γ, interleukin (IL)-4, transforming growth factor beta (TGF)-ß1, and IL-17 were measured by enzyme-linked immunosorbent assay. The localization and expression of TACI, B-cell maturation antigen (BCMA) and B cell activating factor-receptor (BAFF-R) were investigated by immunohistochemistry and western blotting analysis in MLN. Administration of TACI-Ig significantly reduced histological changes, along with decreased Th1 and Th17-cell cytokines and increased CD4(+)CD25(+)FOXP3(+) regulatory T cell (Treg) and Th2-cell cytokines in MLN of AA rats. The levels of BLyS and APRIL were decreased in MLN homogenate of AA rats after treatment with TACI-Ig. TACI-Ig inhibited TACI and BCMA expression, and increased BAFF-R expression in MLN with AA rats. Taken together, BLyS/APRIL-receptors signaling are important not only for B cell function but for T cell-mediated immune responses. TACI-Ig might exert its anti-inflammatory and immunoregulatory effects through inducing immune balance of Th1/Th2 and Treg/Th17 in peripheral MLN. The mechanisms of TACI-Ig on BLyS/APRIL-receptors-dependent signaling in MLN lymphocytes may play key roles in the pathogenesis of autoimmune disorders.