Abstract LB-190: Single-cell polyfunctionality of circulating CD4+ T cells correlates with T cell receptor repertoire diversity of PBMCs, indicating potential synergistic activity and peripheral biomarker predictive of efficacy of intratumor injection of the toll-like receptor 4 agonist G100

Predictive biomarker plays a crucial role in identifying cancer patients who might benefit from a therapy and facilitating a personalized medication. Polyfunctional T cells (co-secretion of 2+ proteins per cell) measured by single-cell IsoCode chip proteomics was demonstrated to predict patient response to CAR-T therapy. Herein, we utilized the IsoCode chip technology to study the efficacy of G100 on eliciting systemic polyfunctional T cells and the association of T cell polyfunctionality with the diversity of T cell receptor (TCR) repertoire in patients with soft tissue sarcomas (STS). PBMC were collected pre- and post-treatment from patients with metastatic STS treated with intratumoral (IT) G100. CD4+ and CD8+ T cells were enriched by microbeads, stimulated with anti-CD3/CD28 at 37°C, 5% CO2 for 24 hours and loaded into an IsoCode chip containing ~12,000 microchambers pre-patterned with a complete copy of a 32-plex antibody array. After 16-hour incubation, protein secretions were analyzed from ~1000 single cells; polyfunctional profile was evaluated across 5 groups: Effector: Granzyme B, TNF-α, IFN-γ, MIP-1α, Perforin, TNF-β; Stimulatory: GM-CSF, IL-2, IL-5, IL-7, IL-8, IL-9, IL-12, IL-15, IL-21; Chemoattractive: CCL11, IP-10, MIP-1β, RANTES; Regulatory: IL-4, IL-10, IL-13, IL-22, sCD137, sCD40L, TGF-β1; Inflammatory: IL-6, IL-17A, IL-17F, MCP-1, MCP-4, IL-1β. Polyfunctional strength index (PSI) was calculated as the percentage of polyfunctional cells multiplied by the intensities of secreted proteins. TCR deep sequencing of PBMCs was performed to evaluate the TCR repertoire diversity. Both CD4+ and CD8+ T cells had heterogeneous polyfunctional profiles pre- and post-treatment. CD4+ T cells showed a marked increase in polyfunctionality while CD8+ T cells exhibited a polyfunctional decrease after treatment. A greater variety of proteins associated with antitumor immunity was detected in CD4+ T cells post treatment. TNF-α, IL-8, Granzyme B, IL-5, MIP-1β and sCD137 primarily drove the enhanced PSI of CD4+ T cells. More importantly, the pre-treatment CD4 PSI positively correlated with the TCR diversity of PBMCs (P = 0.0185). Interestingly, the functional subgroups of effector, stimulatory and regulatory secretions, but not chemoattractive and inflammatory secretions, contributed to the significant association between pretherapy CD4 PSI and PBMC diversity. Single-cell multiplexed proteomics sensitively identifies circulating polyfunctional T cells induced by IT injection of G100 in patients with STS. The pre-treatment PSI of blood CD4+ T cells correlates with TCR diversity, providing a potential peripheral metric to predict patient response to G100 for the development of more effective therapeutics.

Citation Format: Sean Mackay, Jon Chen, Jeremy Patino, Y. David Seo, Seth Pollack, Jing Zhou. Single-cell polyfunctionality of circulating CD4+ T cells correlates with T cell receptor repertoire diversity of PBMCs, indicating potential synergistic activity and peripheral biomarker predictive of efficacy of intratumor injection of the toll-like receptor 4 agonist G100 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr LB-190.

Effect of intratumoral (IT) injection of the toll-like receptor 4 (TLR4) agonist G100 on a clinical response and CD4 T-cell response locally and systemically

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Background: Soft tissue sarcomas (STS) are heterogeneous tumors which are morbid and lethal. G100 is under investigation in multiple clinical trials and contains a potent TLR4 agonist (oil-in-water emulsion of glucopyranosyl lipid A) that has been tested as vaccine adjuvant. We hypothesized IT G100 would induce robust local and potentially systemic anti-tumor immune response, leading to improved outcomes. Methods: 15 metastatic STS patients with superficial lesions were treated with weekly IT G100 for 8-12 wks; 12 patients received radiation (RT) for 2 wks to start, while 3 received IT G100 for 6 wks prior to RT. Biopsies and PBMC were collected pre and post treatment, and flow cytometry was performed on biopsies. TIL and PBMC were analyzed with TCR deep sequencing. PBMC were analyzed by single cell multiplex cytokine profiling. Results: No grade ≥ 3 toxicity was observed, and local tumor control was achieved in all evaluable tumors (14/14). Treated tumors tracked post-trial (mean 156 days) had persistent local control with 1 CR (7%), 1 PR (7%), and 11 SD (79%). In 3 patients with long term follow up, treated lesions remained controlled vs index lesions (-53% vs +31% at mean 235 days, p = 0.002). In all tumors after G100 alone, T cell infiltration increased. In P14, CD3 live cells in tumor rose from < 1% to 62%. PBMC clonality increased in 8/14 tested including P06, who had 4× increase in clonality and CR in the injected lesion; PBMC and TIL TCR overlap increased from 13.4% to 21.5%. P13 had a 2.3× rise in TIL clonality; the top clone (a CD4 T cell) expanded from 0.1% to 38% and expressed more TNFα than the rest (p < 0.0001). Single cell cytokine analysis of PBMC showed 7/13 (54%) increased in polyfunctionality (producing > 2 cytokines) in CD4 T cells; no consistent increase was seen in CD8 T cells. TNFα levels in pre-treatment monocytes correlated with PFS (R2= 0.5, p = 0.02). Conclusions: IT G100 is a viable agent for local control of metastatic STS lesions. With or without RT, G100 appears to cause CD4 T cell mediated local and systemic response. Combination of G100 with other immunomodulators could induce clinically significant systemic responses, as seen in follicular NHL treated with G100. Clinical trial information: NCT02180698.