Abstract 43P
Background
Treatment with autologous tumor-infiltrating lymphocytes (TILs) can induce remarkable clinical responses. The absolute numbers of CD8+ T cells in TIL products have been shown to correlate with clinical responses upon TIL therapy. With the current production process, the numbers of CD8+ T cells in the TIL products vary greatly between patients. By using a targeted cytokine that preferentially activates CD8+ T cells, we aimed to increase the cytotoxic potential of the TIL products.
Methods
A cis-targeted CD8-IL2 molecule (Asher Biotherapeutics) was used to promote CD8+ T cell outgrowth from tumor digests. In the rapid expansion protocol (REP), TILs were subjected to polyclonal stimulation using anti-CD3 antibodies (OKT-3) or anti-CD3/CD28 polymers (TransAct™) in the presence of CD8-IL2. The standard ‘young TIL’ production process using high dose IL-2 and OKT-3 was used as a standard comparison. TIL product composition, T cell differentiation phenotype and tumor-reactivity was assessed by flow cytometry and ELISA.
Results
7 tumors (5 melanoma, 1 cervical carcinoma and 1 endometrial carcinoma) were subjected to enzymatic digestion. At the end of the REP phase, TIL products cultured with CD8-IL2 contained 97.5% (range 92-98%) CD8+ T cells, compared to 77.2% (range 35-81%) for products cultured with conventional IL-2 (p = 0.036). Highest total CD8+ T cell numbers were obtained using CD8-IL2 in combination with TransAct in the REP. T cell differentiation phenotypes of the TIL products generated with CD8-IL2 were similar to the standard production process, showing that the improved expansion and CD8+ T cell enrichment did not come at the expense of a more exhausted phenotype. Upon restimulation with tumor digest clear anti-tumor reactivity of the TIL products could be demonstrated based on IFN-y production and tumor cell kill.
Conclusions
This study shows that CD8 cis-targeted IL-2 can be used to generate TIL products mainly comprising CD8+ T cells, thereby potentially improving cytotoxic potential and therapeutic efficacy. The use of CD3/28 TransAct, compared to anti-CD3 stimulation (OKT-3) improved the final yield of CD8+ T cells in the TIL products.
Legal entity responsible for the study
Netherlands Cancer Institute.
Funding
Asher Biotherapeutics.
Disclosure
L. Tas: Financial Interests, Institutional, Funding: Asher Biotherapeutics. M. van Zon: Financial Interests, Institutional, Funding: Asher Biotherapeutics. I. Djuretic: Financial Interests, Institutional, Full or part-time Employment: Asher Biotherapeutics. K.D. Moynihan: Financial Interests, Institutional, Full or part-time Employment: Asher Biotherapeutics. Y.A. Yeung: Financial Interests, Institutional, Full or part-time Employment: Asher Biotherapeutics. N. Mathewson: Financial Interests, Institutional, Full or part-time Employment: Asher Biotherapeutics. J.B.A.G. Haanen: Financial Interests, Institutional, Advisory Board: Bristol Myers Squibb, Achilles Therapeutics, Ipsen, Merck Sharpe & Dohme, Merck Serono, Pfizer, Molecular Partners, Novartis, Roche, Sanofi, Third Rock Venture, Iovance Biotherapeutics; Financial Interests, Institutional, Advisory Board, SAB member: BioNTech, Immunocore, Gadeta, Instil Bio, PokeAcel, T-Knife; Financial Interests, Personal, Advisory Board, SAB member: Neogene Therapeutics, Scenic; Financial Interests, Personal, Stocks/Shares: Neogene Therapeutics; Financial Interests, Institutional, Research Grant: Bristol Myers Squibb, BioNTech US, Merck Sharpe & Dohme, Amgen, Novartis, Asher Bio; Non-Financial Interests, Personal, Member: ASCO, AACR, SITC; Other, Personal, Other, Editor-in-Chief IOTECH: ESMO; Other, Personal, Other, Editorial Board ESMO Open: ESMO; Other, Personal, Other, Editorial Board: Kidney Cancer. I. Jedema: Financial Interests, Institutional, Funding: Asher Biotherapeutics.