Carr, Allison

Abstract Multiple Myeloma is the second most common hematologic malignancy among US adults and remains incurable. Immunotherapies, including bispecific T cell engagers (BiTEs) targeting BCMA, have greatly improved outcomes. However, a significant fraction of patients still fail to respond, or develop resistant disease. Conventional models of T cell cytotoxicity focus on delivery of perforin- and granzyme-containing granules following antigen recognition and T cell activation, an inefficient mode of killing that requires effector-to-target cell contact. Activated T cells, however, also secrete cytokines capable of diffusing and acting on distant targets. This raises the possibility of paracrine killing, in which these cytokines induce tumor cell death independently of cell-cell contact.Tumor necrosis factor (TNF) is a key cytokine released during T cell activation and is unique in that it can drive either cell survival or cell death. Although most cells default to cell survival and NFkB-mediated inflammation, several modulators can shift this survival signaling toward cell death. We therefore hypothesized that sensitizing Myeloma cells to TNF could enable T cell paracrine killing and enhance the efficacy of anti-Myeloma T cell immunotherapies.To test this, we first established an in vitro model of clinical response to Teclistamab, a BCMA-directed BiTE, using Multiple Myeloma cell lines that displayed sensitive, intermediate, or resistant responses to T cell killing. Combining these data with assays of cytokine sensitivity and receptor expression, we found that susceptibility to TNF-mediated cell death was a major determinant of Teclistamab sensitivity. This correlation was further supported by reduction or complete abrogation of Teclistamab T cell killing of sensitive Myeloma cell lines when soluble TNF was neutralized from these co-cultures using monoclonal antibodies. Pharmacologic inhibition and CRISPR-mediated deletion of known regulators of TNF survival-signaling further sensitized Myeloma cells to both TNF and T cell killing. In the absence of these regulators, BCMA-negative myeloma targets retained sensitivity to Teclistamab, supporting the idea that the main mechanism of cell death was indeed paracrine killing.Together, these findings establish a direct link between TNF sensitivity and T cell-mediated killing of Myeloma cells, and support TNF-driven paracrine killing as a dominant mechanism of response to Teclistamab. Enhancing this TNF-mediated death signaling may therefore represent a strategy to overcome resistance and improve clinical efficacy of T cell-based immunotherapies in Multiple Myeloma. Citation Format: Allison Carr, Elise Sintim-Aboagye, Adrian Ting, . TNF-driven paracrine killing determines the cytotoxic efficacy of Teclistamab in Myeloma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 1636.

Abstract Multiple myeloma (MM) is the second most common hematologic malignancy among US adults, characterized by high rates of relapse and refractory disease. Anti-Myeloma T cell immunotherapies, such as chimeric antigen receptors (CAR-Ts) and bispecific T cell engagers (BiTEs), have been able to induce deep responses in the clinic and extending survival for many. However, even these responses are not durable and majority of patients still relapse. MM cell signaling in response to cytokines released by these T cells, such as Tumor Necrosis Factor (TNF) Alpha, and Interferon gamma (IFNγ), may offer additional insight into mechanisms of relapse and resistance as well as avenues of therapeutic manipulation. To evaluate the effects of TNF and IFNγ on MM cell death and proliferation, we obtained human MM cell lines (MMCLs) and stably transduced them with a GFP-NLS reporter. We then monitored these cell lines in the presence of TNF, IFNγ, or TNF+IFNγ and tracked their cell death and growth kinetics over time using DiYO-3 incorporation and GFP count, respectively, via IncuCyteS3 live cell imaging. We next utilized Teclistamab, a B cell maturation antigen (BCMA)-directed BiTE, to co-culture MMCLs with healthy donor derived T cells at various effector to target (E:T) ratios and monitored for T cell mediated death again via IncuCyteS3 live cell imaging. While all MMCLs were able to be killed at high E:T ratios (1:1), only cytokine-sensitive lines remained susceptible to T cell killing at lower E:T ratios (1:10). The addition of TNF and/or IFNγ blocking antibodies confirmed that the increased sensitivity of these lines to T cell killing was indeed mediated by the two cytokines. In summary, were able to show an in vitro model of differential MM cell response to Teclistamab mediated T cell killing, and that this difference in response was predicated on the MM cells’ baseline sensitivity to cytokine mediated cell death via TNF and IFNγ. Thus, further dissecting mechanisms underlying resistance or sensitivity of MM cells to cytokine induced death could suggest therapeutic targets with the potential to enhance the efficacy of anti-MM T cell immunotherapies. Citation Format: Allison Carr, Adrian Ting. Role of cytokine-induced cell death on efficacy of teclistamab-mediated T cell killing of multiple myeloma cells. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 1380.