Background NY-ESO-1–specific T cells (letetresgene autoleucel [lete-cel] GSK3377794) are autologous CD4+ and CD8+ T cells transduced to express a high-affinity T-cell receptor (TCR) capable of recognizing NY-ESO-1 and LAGE-1a antigens in complex with human leukocyte antigen (HLA)-A*02. NY-ESO-1 (CTAG1B) and LAGE-1a (CTAG2) are tumor-associated antigens (TAA) that share the SLLMWITQC peptide bound to human leukocyte antigen HLA-A*02 and are expressed in various cancers. Emerging evidence suggests that TCR-engineered T cells targeting NY-ESO-1 hold promise for patients with solid tumors.¹ Approximately 75% of synovial sarcomas can over-express NY-ESO-1 vs 12% of NSCLC,² however, NSCLC expression of NY-ESO-1/LAGE1-a may have therapeutic potential.³ A separate study using engineered T cells targeting NY-ESO-1 has shown a partial response in a patient with advanced lung adenocarcinoma.⁴ Decitabine (DAC) is a hypomethylating agent and potent inducer of TAA, including NY-ESO-1.⁵ We have reported in vitro use of DAC to selectively modulate TAA expression in TAA low-expressing tumor cell lines in order to enhance lete-cel therapy.³ The aim of this study was to assess enhancement of combination therapy with lete-cel and DAC in an in vivo NSCLC model.

Methods NOD scid gamma (NSG) mice were injected subcutaneously with the human NSCLC tumor cell line NCI-H1703. Upon engraftment, tumor-bearing mice were treated with a 5-day course of DAC or vehicle control followed by 2 days of rest. Lete-cel was infused on Day 8. RNA was isolated from tumor formalin-fixed paraffin-embedded blocks, and levels of NY-ESO-1 and LAGE-1a transcript were measured by RT-qPCR. Expression pattern of the NY-ESO-1 protein was assessed via immunohistochemistry. Efficacy was defined by changes in tumor volume and systemic IFN-γ secretion.

Results Consistent with our previous in vitro studies, DAC treatment in vivo resulted in induction of NY-ESO-1 and LAGE-1a in NSCLC tumors. Lete-cel in combination with DAC significantly enhanced antitumor efficacy in vivo compared with lete-cel alone. This was associated with increased interferon-γ secretion. Mice that received DAC treatment only did not show statistically significant tumor reduction compared with untreated mice.

Ethics Approval All animal studies were ethically reviewed and carried out in accordance with Animals (Scientific Procedures) Act 1986 and the GSK Policy on the Care, Welfare and Treatment of Animals. Human biological samples were sourced ethically and their research use was in accord with the terms of the informed consents under an Institutional Review Board/Ethics Committee approved protocol.

Conclusions GSK is currently enrolling a Phase Ib/IIa, multi-arm, open-label pilot study (NCT03709706) of lete-cel as a monotherapy or in combination with pembrolizumab in HLA-A*02–positive patients with NSCLC whose tumors express NY-ESO-1/LAGE-1a. This work may support rationale for the use of DAC in combination with lete-cel to improve adoptive T-cell therapy by increasing levels of target antigens and antitumor effect in NSCLC.

Acknowledgements Funding: GSK

References

1. D’Angelo SP, Melchiori L, Merchant MS, et al. Cancer Discov 2018;8:944–957.

2. Kerkar SP, Wang Z-F, Lasota J, et al. J Immunother 2016;39:181–187.

3. Eleftheriadou I, Brett S, Domogala A, et al. Ann Oncol 2019:30(Suppl 5):v475–v532.

4. Xia Y, Tian X, Wang J, et al. Oncol Lett 2018;16:6998–7007.

5. Schrump DS, Fischette MR, Nguyen DM, et al. Clin Cancer Res 2006;12:5777–5785.