TIG-007: Study of EOS884448/GSK4428859A Alone, and in Combination with Iberdomide with or without Dexamethasone, in Participants with Relapsed or Refractory Multiple Myeloma

Background: T-cell immunoreceptor with Ig and ITIM domains (TIGIT) is an inhibitory immune checkpoint receptor expressed on subsets of T cells and NK cells. In multiple myeloma (MM), TIGIT expression increases as the disease progresses and correlates with defective T cell effector functions. Higher TIGIT expression was observed in MM bone marrow CD8+ T cells in mice and patients compared to other immune checkpoint inhibitors, including PD-1, TIM-3, LAG-3, or CTLA-4 (Guillerey, C. et al, Blood 2018; Minnie, S. A. et al . Blood 2018). EOS884448/GSK4428859A (EOS-448) is a potent and highly selective fully human antagonist IgG1 antibody targeting TIGIT. Preclinically, anti-TIGIT Ab elicits superior anti-tumor immune responses compared to anti-PD1 mAbs (Guillerey, C. et al, Blood 2018). In murine Vk*Myc MM models, Fc-enabled a-TIGIT Ab elicits effective control of MM disease progression after autologous stem-cell transplant (ASCT), while Fc-disabled version is inactive. Anti-tumor activity is seen with monotherapy after ASCT at high T cell doses and provides significant synergistic activity when combined with an Immunomodulatory imide drug (IMiD) if T cell doses are suboptimal (Minnie, S. A. et al, Abstract submitted ASH 2021). Iberdomide (also known as CC-220) is a novel potent cereblon (CRBN) E3 ligase modulatory compound (CELMoD) that regulates multiple transcription factors within immune cells (Gandhi, A. K. et al . Brit J Haematol 2014). Iberdomide has shown notable clinical activity and acceptable tolerability in heavily pre-treated patients with relapsed or refractory multiple myeloma (RRMM), including those refractory to prior IMiDs (Lonial, S. et al. J Clin Oncol 2019). Given the dominant role of TIGIT in the immune suppression associated with MM, we hypothesize that TIGIT represents an ideal checkpoint to target clinically. EOS-448 alone or the synergistic combination of EOS-448 with iberdomide may provide a therapeutic opportunity to amplify myeloma-specific T-cell anti-tumor responses in difficult to treat RRMM patients previously exposed to IMiD, proteasome inhibitors (PIs) and anti-CD38.

Methods: This phase I/II, open-label, multicenter, dose-escalation/expansion study will assess the safety, tolerability and preliminary activity of EOS-448 as monotherapy and in combination with iberdomide with or without dexamethasone in up to 158 adults with RRMM, who have progressed after prior treatments with IMiDs, PI and anti-CD38. EOS-448 will be infused intravenously on Day 1 of 28-day cycles. In Part 1, the safety and tolerability of EOS-448 as monotherapy and in combination with iberdomide with or without dexamethasone will be assessed in cohorts of up to 18 participants to identify the maximum tolerated dose and recommended phase II dose (RP2D) in each of the 3 treatment arms. In Part 2, the safety and anti-cancer activity of the RP2D will be assessed in up to 102 RRMM participants. Primary endpoints are treatment emergent adverse events, laboratory abnormalities, dose-limiting toxicities and clinical activity according to the International Myeloma Working Group (IMWG) Uniform Response Criteria. Secondary endpoints include overall response rates, duration of response, PK, and antidrug antibodies. Exploratory biomarkers including study treatment-mediated pharmacodynamic (PD) effects, PK-PD correlations, and correlative analyses of predictive and PD measurements with response, toxicity, and resistance will be investigated. Minimal residual disease (MRD) status with therapy will also be assessed as clinically indicated. The study is planned to open in November 2021 in North America and Europe.