Teclistamab is an active T cell-redirecting bispecific antibody against B-cell maturation antigen for multiple myeloma

Abstract

B-cell maturation antigen (BCMA), a member of the tumor necrosis factor family of receptors, is predominantly expressed on the surface of terminally differentiated B cells. BCMA is highly expressed on plasmablasts and plasma cells from multiple myeloma (MM) patient samples. We developed a BCMAxCD3 bispecific antibody (teclistamab [JNJ-64007957]) to recruit and activate T cells to kill BCMA-expressing MM cells. Teclistamab induced cytotoxicity of BCMA+ MM cell lines in vitro (H929 cells, 50% effective concentration [EC50] = 0.15 nM; MM.1R cells, EC50 = 0.06 nM; RPMI 8226 cells, EC50 = 0.45 nM) with concomitant T-cell activation (H929 cells, EC50 = 0.21 nM; MM.1R cells, EC50 = 0.1 nM; RPMI 8226 cells, EC50 = 0.28 nM) and cytokine release. This activity was further increased in the presence of a γ-secretase inhibitor (LY-411575). Teclistamab also depleted BCMA+ cells in bone marrow samples from MM patients in an ex vivo assay with an average EC50 value of 1.7 nM. Under more physiological conditions using healthy human whole blood, teclistamab mediated dose-dependent lysis of H929 cells and activation of T cells. Antitumor activity of teclistamab was also observed in 2 BCMA+ MM murine xenograft models inoculated with human T cells (tumor inhibition with H929 model and tumor regression with the RPMI 8226 model) compared with vehicle and antibody controls. The specific and potent activity of teclistamab against BCMA-expressing cells from MM cell lines, patient samples, and MM xenograft models warrant further evaluation of this bispecific antibody for the treatment of MM. Phase 1 clinical trials (monotherapy, #NCT03145181; combination therapy, #NCT04108195) are ongoing for patients with relapsed/refractory MM.

Graphical abstract

Figure 1.

Teclistamab-induced cytotoxicity and activation of T cells in vitro. (A) Cytotoxicity of various BCMA⁺ MM cell lines (H929, MM.1R, and RPMI 8226) or BCMA^– cells (MV4-11) in the presence of teclistamab and healthy T cells for 48 hours. (B) Activation of T cells as evidenced by the CD25 cell surface marker. No lysis or T-cell activation was observed in the BCMA^– cell line MV4-11 or with the control antibodies BCMAxNull or NullxCD3. The data points closely aligned with the generated fit curve with minimal donor-to-donor (n = 6 donors) variability. (C) BCMA detection on the surface of various BCMA⁺ cells (H929, MM.1R, and RPMI 8226) and BCMA^– cells (MV4-11) by FACS. Solid red line, BCMA; dotted/gray shading, isotype control. (D) Ligand (APRIL and BAFF) mediated P38 phosphorylation and teclistamab failed to induce any phosphorylation signal as measured by western blot.

Figure 2.

Teclistamab-induced cytotoxicity and activation of MM BM MNC cells ex vivo. Each row represents a different patient sample. Frozen BM MNCs were incubated with various concentrations of teclistamab (0-532 nM) with or without exogenous healthy T cells to measure target binding and killing. BCMA protein density was 2451 receptors per plasma cell in one of the patient samples (ID BM 240 MM). (A) Dose-dependent binding of teclistamab to target cells. (B) Dose-dependent plasma cell depletion. BM MNCs were incubated for 48 hours with exogenous healthy T cells at a 1:1 E:T ratio in the presence of teclistamab and depletion measured as remaining CD138⁺ cells. (C) Teclistamab-mediated T-cell activation was measured via flow cytometry by gating T cells using CD3 surface marker and CD25 activation marker. Percent CD25⁺ T cell values were plotted on the y-axis. Teclistamab was able to activate T cells efficiently when incubated with BM MNCs, whereas the control antibodies had no effect.

Figure 3.

Teclistamab activity in a whole blood assay. (A) Whole blood from 3 healthy human donors was stained with teclistamab. Staining intensity for 1 representative donor is shown in the panels, where solid green lines represent teclistamab, and filled dotted lines are the corresponding isotype. No BCMA expression was observed on lymphocytes (B cells were gated by using CD19 marker), monocytes, granulocytes, NK cells, or plasmacytoid dendritic cells (DCs) in 3 healthy donors. In contrast, the antibody bound to T cells (CD4⁺ and CD8⁺) and NK T cells as expected because they express CD3. (B) Dose–response curve of H929 cytotoxicity and T-cell activation as measured by percent CD25⁺ T-cell population in whole blood after 48-hour incubation with teclistamab. The graphs depict the mean (± standard error of the mean [SEM]) of 6 individual donors.

Figure 4.

Impact of sBCMA on teclistamab activity. (A) Plasma from patients with MM had significantly higher levels of sBCMA than plasma from healthy donors (average, 89.91 vs 8.04 ng/mL, respectively). (B) sBCMA levels were higher in patients with refractory MM compared with patients who were treatment (Tx) naive or had active MM. (C) Cytotoxicity. (D) T-cell activation potential of teclistamab was measured in the presence of various concentrations of sBCMA, APRIL, and BAFF.

Figure 5.

Effects of a γ-secretase inhibitor on BCMA surface expression and teclistamab activity. (A) H929 and MV4-11 cells were incubated with a γ-secretase and TAPI inhibitors at various concentrations for 0 to 72 hours, and BCMA surface expression was measured by using FACS. (B) MM patient BM MNCs were incubated with a γ-secretase inhibitor, and BCMA surface expression was measured. (C) Teclistamab was incubated with H929 cells in the presence of healthy T cells with or without a γ-secretase inhibitor, and cytotoxicity and T-cell activation were measured after 48 hours.

Figure 6.

Antitumor activity of teclistamab in xenograft models. (A) In the H929 prophylactic model, teclistamab had antitumor efficacy with significant reduction of tumor formation and growth compared with PBS-treated control mice, at dose levels of either 0.5 or 1 µg per animal; BCMAxNull and NullxCD3 bispecific antibodies, however, failed to suppress tumorigenesis in the model. (B) In the established RPMI 8226 model, teclistamab displayed antitumor effects at both the 10 and 50 µg per animal dose compared with PBS-treated control mice. Human pan-T cells were activated and expanded in vitro by using a T-cell activation and expansion kit (Miltenyi Biotec) and grown in medium containing IL-2 (0.1 µg/µL). Results are presented as average tumor volume, expressed in mm³ ± SEM of each group. Tumor volume was calculated by using the following formula: tumor volume (mm³) = (a × b²/2), where a represents the length and b the width of the tumor as determined by caliper measurements.