T cell engager (TCE) score in patients treated with bispecific CD3 TCE in phase I clinical trials

2573 Background: Immune prognostic scores, such as the Gustave Roussy Immune (GRIM) score have been investigated in patients (pts) treated with immune check-point blockers. We aimed to determine whether we could improve the selection of pts that could benefit from new immunotherapies such as bispecific CD3 T cell engagers (TCE) antibodies in pts treated in phase I clinical trials (CT), by building a new prognostic score. Methods: All patients treated with bispecific CD3 TCE in phase I CT from July 2018 to February 2023 at the Drug Development Department at Gustave Roussy were enrolled in the study. Univariate and multivariate analyses (UVA and MVA) were conducted on demographic, clinical and biological data to assess their prognostic value on progression free survival (PFS). MVA results were used to build a new prognostic score (TCE score). This score was then validated on overall survival (0S). The predictive ability (on PFS and OS) of the TCE score was assessed using Harrell’s C index. It was compared with the GRIM and Royal Marsden Hospital (RMH) scores predictive ability on PFS and OS. Results: A total of 67 patients (47 men, 20 women) with metastatic solid cancer or advanced hematological cancer were included. Median age was 62 years old. The most represented tumor types were prostate cancer (33%), lymphoma (25%) and small cell lung carcinoma (24%). UVA on PFS showed that elevated C-reactive protein (CRP) (HR: 2,36; 95%CI: 1,35-4,16; p = 2.10 -3 ) and lactate dehydrogenase (LDH) (HR: 3,00; 95%CI: 1,63-5,53; p = 2.10 -4 ) were associated with a worst PFS. In MVA, LDH (HR: 2,49; 95% CI: 1,30-4,74, p = 1.10 -4 ) and CRP levels (HR: 1,92; 95% CI: 1,1-3,46; p = 1.10 -4 ) were independent negative prognostic factors for PFS. The TCE score was based on MVA results (CRP>10g/l: +1; LDH > 250U/l: +1). It showed that pts with a high score (1-2) had a shorter PFS (median PFS: 2,8 months) and OS (median OS: 9,9 months) than low score (0) pts (median PFS: 5,8 months; median OS: not reached). TCE score’s Harrell’s C index for PFS was 0,63 and 0,64 for OS. For GRIM and RMH scores, Harrell’s C index for PFS were respectively 0,60 and 0,55. For OS it was respectively 0,58 and 0,53. Conclusions: To select patients for Bispecific CD3 TCE phase I CT, we built a new prognostic score, based on LDH and CRP levels, that can be used as prognostic of PFS and OS. TCE score is more reliable than GRIM and RMH scores to prognose PFS and OS.