Abstract 5777
Background
THOR-707 is a reprogrammed, site-directed, single pegylated, recombinant human IL-2 (rIL-2) variant that lacks binding affinity for the α chain of the IL-2 receptor. Because THOR-707 has near-native binding affinity for the βγ chain of the IL-2 receptor, it produces an immune-active, CD8+ T effector-driven anti-tumor effect. At the same time because it lacks α chain affinity, it limits the proliferation of immune suppressive CD4+ Tregs and other innate lymphoid cells known to mediate the life-threatening complications of VLS. These pharmacologic properties make THOR-707 an ideal immunooncology drug development candidate.
Methods
We employed in vivo and ex vivo models to study pharmacodynamic responses to THOR-707.
Results
We demonstrate all critical actions of IL-2 for anti-tumoral responses without inducing VLS, including: (1) maximal extravasation and expansion of key CD8+ T and NK cell populations in mice and NHPs (2) CD8+ T cell infiltration of tumor and lymph nodes in mouse tumor models, critical for antigen presentation by tumor cells and trans-presentation by antigen presenting cells and (3) induction of IFNγ release ex vivo by T cell receptor (TCR)-activated human T cells that is further potentiated by a PD-1 inhibitory antibody, important for upregulation of MHC I and II and enhancement tumor antigen presentation. In mouse syngeneic tumor models, THOR-707 promoted an increase in the number of infiltrating tumor-killing NK and CD8+ T cells without expansion of suppressive CD4+ Treg cells. Expression profiling of tumors revealed promotion of remodeling of cellular populations towards a composition favoring cytolytic phenotypes. Evaluation of TCR clonality revealed that treatment with THOR-707 increased intra-tumoral T cell diversity.
Conclusions
THOR-707 induction of CD8+ T cell tumor infiltration resulted in single agent dose-dependent anti-tumor efficacy, additive efficacy in combination with a PD-1 checkpoint inhibitor, promoted long-term survival in mice and NHPs and rejection of tumor cells on re-challenge. Based on these results, first in human studies are expected to begin this year in solid tumors both as a single agent and in combination with an immune-checkpoint inhibitor.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Synthorx, Inc.
Funding
Synthorx, Inc.
Disclosure
M.E. Milla: Leadership role, Shareholder / Stockholder / Stock options, Licensing / Royalties, Full / Part-time employment: Synthorx, Inc.; Licensing / Royalties: Adaptive Biotechnologies, Inc. J.L. Ptacin: Full / Part-time employment: Synthorx, Inc. L. Ma: Full / Part-time employment: Synthorx, Inc. C.E. Caffaro: Full / Part-time employment: Synthorx, Inc. H.R. Aerni: Full / Part-time employment: Synthorx, Inc. K.M. San Jose: Full / Part-time employment: Synthorx, Inc. M.J. Pena: Full / Part-time employment: Synthorx, Inc. R.W. Herman: Full / Part-time employment: Synthorx, Inc. Y. Pavlova: Full / Part-time employment: Synthorx, Inc. D.B. Chen: Full / Part-time employment: Synthorx, Inc. T.K. Ismaili: Full / Part-time employment: Synthorx, Inc. S. Li: Full / Part-time employment: Synthorx, Inc. J. Nguyen: Full / Part-time employment: Synthorx, Inc. N. Singh: Full / Part-time employment: Synthorx, Inc. L.K. Shawver: Leadership role, Shareholder / Stockholder / Stock options, Licensing / Royalties, Officer / Board of Directors: Synthorx, Inc.; Shareholder / Stockholder / Stock options: Cleave Biosciences; Shareholder / Stockholder / Stock options: Relay Therapeutics. L.K. Koriazova: Full / Part-time employment: Synthorx, Inc. I.B. Joseph: Full / Part-time employment: Synthorx, Inc.
Resources from the same session
1242 - Monalizumab in combination with cetuximab in patients (pts) with recurrent or metastatic (R/M) head and neck cancer (SCCHN) previously treated or not with PD-(L)1 inhibitors (IO): 1-year survival data.
Presenter: Roger Cohen
Session: Poster Display session 3
Resources:
Abstract
4703 - Updated results of a phase II study evaluating accelerator-based boron neutron capture therapy (AB-BNCT) with borofalan(10B) (SPM-011) in recurrent squamous cell carcinoma (R-SCC-HN) and recurrent and locally advanced non-SCC (R/LA-nSCC-HN) of the head and neck
Presenter: Katsumi Hirose
Session: Poster Display session 3
Resources:
Abstract
3638 - Phase 3 KEYNOTE-048 Study of First-Line (1L) Pembrolizumab (P) for Recurrent/Metastatic (R/M) Head and Neck Squamous Cell Carcinoma (HNSCC): Asia vs Non-Asia Subgroup (subgrp) Analysis
Presenter: Makoto Tahara
Session: Poster Display session 3
Resources:
Abstract
2954 - Integrated data review evaluating safety, pharmacokinetics (PK) and immunogenicity of RM-1929 photoimmunotherapy (PIT) in subjects with locoregional, recurrent head and neck squamous cell carcinoma (rHNSCC).
Presenter: Jennifer Johnson
Session: Poster Display session 3
Resources:
Abstract
3629 - First line versus second line immunotherapy in recurrent/metastatic squamous cell carcinoma of the head and neck
Presenter: Caroline Even
Session: Poster Display session 3
Resources:
Abstract
767 - Sensitizing HRAS overexpressing head and neck squamous cell carcinoma (HNSCC) to chemotherapy
Presenter: Theodoros Rampias
Session: Poster Display session 3
Resources:
Abstract
4985 - A Single-Arm, Open-Label, Multicenter, Phase IIIb Clinical Trial with Nivolumab in Subjects with Recurrent or Metastatic Platinum-refractory Squamous Cell Carcinoma of the Head and Neck.
Presenter: Paolo Bossi
Session: Poster Display session 3
Resources:
Abstract
1564 - Long-term Results of Phase 2 Trial of Reduced Modified Clinical Target Volume in Low-risk Nasopharyngeal Carcinoma Treated with Intensity Modulated Radiotherapy
Presenter: Jingjing Miao
Session: Poster Display session 3
Resources:
Abstract
3356 - To compare two oral mucosa contouring methods in predicting acute oral mucocitis in nasopharyngeal carcinoma treated with helical tomotherapy
Presenter: Yuan-Yuan Chen
Session: Poster Display session 3
Resources:
Abstract
1984 - Induction chemotherapy (IC) followed by concurrent chemoradiotherapy (CCRT) in nasopharyngeal carcinoma (NPC)
Presenter: Gizem Kaval
Session: Poster Display session 3
Resources:
Abstract