Reprogramming engineered autologous T cells to overcome resistance in patients with Merkel cell carcinoma
(1) Asano Y (2) Veatch JR (3) Sung CJ (4) Tang TH (5) Mazziotta F (6) Natsuki S (7) McAfee M (8) Bakhtiari J (9) Lee B (10) Martin L (11) Rizzi A (12) Zhang T (13) Smith CW (14) Paulson KG (15) Schmitt TM (16) Newell EW (17) Elz AE (18) Chen DG (19) Su Y (20) Gustafson HH (21) Yeung CCS (22) Seaton B (23) Hunter D (24) Koelle DM (25) Bhatia S (26) Hall ET (27) Voillet V (28) Cao J (29) Gooley T (30) Greenberg PD (31) Gottardo R (32) Oda SK (33) Nghiem P (34) Chapuis AG
Asano, Veatch, and Sung et al. identified TCRMCC1, a high-avidity HLA-A*02:01-restricted TCR targeting Merkel cell polyomavirus large-T antigen and treated seven patients who had ICI-refractory metastatic MCC using autologous TCRMCC1-transduced T cells plus ICB. TTCR-MCC1 cells trafficked to tumors and induced regression in two patients, but HLA class I silencing limited activity. In one patient, delayed regression coincided with endogenous effector T cell activation and restored tumor HLA expression. TTCR-MCC1 cells armored with CD8αβ and a CD200R-CD28 switch receptor showed enhanced tumor infiltration, HLA expression, and control of HLA-low MCC in vivo.
Contributed by Shishir Pant
(1) Asano Y (2) Veatch JR (3) Sung CJ (4) Tang TH (5) Mazziotta F (6) Natsuki S (7) McAfee M (8) Bakhtiari J (9) Lee B (10) Martin L (11) Rizzi A (12) Zhang T (13) Smith CW (14) Paulson KG (15) Schmitt TM (16) Newell EW (17) Elz AE (18) Chen DG (19) Su Y (20) Gustafson HH (21) Yeung CCS (22) Seaton B (23) Hunter D (24) Koelle DM (25) Bhatia S (26) Hall ET (27) Voillet V (28) Cao J (29) Gooley T (30) Greenberg PD (31) Gottardo R (32) Oda SK (33) Nghiem P (34) Chapuis AG
Asano, Veatch, and Sung et al. identified TCRMCC1, a high-avidity HLA-A*02:01-restricted TCR targeting Merkel cell polyomavirus large-T antigen and treated seven patients who had ICI-refractory metastatic MCC using autologous TCRMCC1-transduced T cells plus ICB. TTCR-MCC1 cells trafficked to tumors and induced regression in two patients, but HLA class I silencing limited activity. In one patient, delayed regression coincided with endogenous effector T cell activation and restored tumor HLA expression. TTCR-MCC1 cells armored with CD8αβ and a CD200R-CD28 switch receptor showed enhanced tumor infiltration, HLA expression, and control of HLA-low MCC in vivo.
Contributed by Shishir Pant
ABSTRACT: Immune checkpoint inhibitors (ICIs) have transformed Merkel cell carcinoma (MCC) outcomes, but most patients with MCC develop resistance. We identified T cell receptor (TCR)MCC1, a highly avid, HLA-A*02:01-restricted TCR targeting the Merkel cell polyomavirus (MCPyV) oncoprotein large-T antigen15-23. Seven patients with ICI-refractory metastatic MCPyV+ MCC received TCRMCC1-transduced cells (TTCR-MCC1 cells) after lymphodepleting chemotherapy or HLA-enhancing interventions [radiation or interferon gamma-1b (Actimmune)], with concurrent ICIs (NCT03747484). TTCR-MCC1 cells trafficked to tumor sites and expressed a gene expression profile compatible with T cell activation, with tumor regression observed in two patients. However, therapeutic activity was limited by HLA class I silencing, a common mechanism of immune escape in MCC. In one patient, delayed tumor regression coincided with endogenous effector immune activation and restoration of MCC HLA expression, implying that robust local responses could reverse HLA silencing. To overcome this barrier, we engineered CD4 and CD8 TTCR-MCC1 cells to coexpress CD8αβ and a CD200R-CD28 switch receptor, enabling CD4 T cell engagement and T cell costimulation. These modifications enhanced tumor infiltration, increased HLA expression, and improved control of HLAlow MCC in vivo in mice. These findings support the feasibility of TCR-engineered cell therapy for MCPyV+ MCC and provide a blueprint for overcoming immune evasion via targeted localized enhancement of antigen presentation.
Author Info:
(1) Translational Science and Therapeutics Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA. (2) Translational Science and Therapeutics Division, Fred Hutchinson Can
cer Center, Seattle, WA 98109, USA. Department of Medicine, University of Washington School of Medicine, Seattle, WA 98195, USA. (3) Translational Science and Therapeutics Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA. (4) Translational Science and Therapeutics Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA. (5) Translational Science and Therapeutics Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA. Department of Medicine, University of Washington School of Medicine, Seattle, WA 98195, USA. (6) Translational Science and Therapeutics Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA. (7) Translational Science and Therapeutics Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA. (8) Translational Science and Therapeutics Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA. Department of Laboratory Medicine and Pathology, University of Washington School of Medicine, Seattle, WA 98195, USA. (9) Translational Science and Therapeutics Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA. (10) Translational Science and Therapeutics Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA. (11) Translational Science and Therapeutics Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA. (12) Translational Science and Therapeutics Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA. (13) Translational Science and Therapeutics Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA. (14) Translational Science and Therapeutics Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA. Department of Medicine, University of Washington School of Medicine, Seattle, WA 98195, USA. (15) Translational Science and Therapeutics Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA. (16) Department of Laboratory Medicine and Pathology, University of Washington School of Medicine, Seattle, WA 98195, USA. Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA. (17) Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA. (18) Translational Science and Therapeutics Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA. (19) Translational Science and Therapeutics Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA. Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA. (20) Department of Pediatrics, University of Washington School of Medicine, Seattle, WA 98195, USA. Ben Towne Center for Childhood Cancer and Blood Disorders Research, Seattle Children's Research Institute, Seattle, WA 98105, USA. (21) Translational Science and Therapeutics Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA. Department of Laboratory Medicine and Pathology, University of Washington School of Medicine, Seattle, WA 98195, USA. (22) Translational Science and Therapeutics Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA. (23) Translational Science and Therapeutics Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA. (24) Department of Medicine, University of Washington School of Medicine, Seattle, WA 98195, USA. Department of Laboratory Medicine and Pathology, University of Washington School of Medicine, Seattle, WA 98195, USA. Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA. Department of Global Health, University of Washington School of Medicine, Seattle, WA 98195, USA. Benaroya Research Institute, Seattle, WA 98101, USA. (25) Department of Medicine, University of Washington School of Medicine, Seattle, WA 98195, USA. Clinical Research Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA. (26) Department of Medicine, University of Washington School of Medicine, Seattle, WA 98195, USA. Clinical Research Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA. (27) Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA. (28) Shared Resources, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA. (29) Translational Science and Therapeutics Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA. (30) Translational Science and Therapeutics Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA. Department of Medicine, University of Washington School of Medicine, Seattle, WA 98195, USA. Department of Immunology, University of Washington School of Medicine, Seattle, WA 98195, USA. Parker Institute for Cancer Immunotherapy, San Francisco, CA 94129, USA. (31) Biomedical Data Science Center, Centre Hospitalier Universitaire Vaudois, 1010 Lausanne, Switzerland. University of Lausanne, 1015 Lausanne, Switzerland. School of Life Sciences, EPFL, 1015 Lausanne, Switzerland. (32) Department of Pediatrics, University of Washington School of Medicine, Seattle, WA 98195, USA. Ben Towne Center for Childhood Cancer and Blood Disorders Research, Seattle Children's Research Institute, Seattle, WA 98105, USA. (33) Translational Science and Therapeutics Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA. Department of Medicine, University of Washington School of Medicine, Seattle, WA 98195, USA. Department of Dermatology, University of Washington School of Medicine, Seattle, WA 98195, USA. (34) Translational Science and Therapeutics Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA. Department of Medicine, University of Washington School of Medicine, Seattle, WA 98195, USA.
Citation: Sci Transl Med 2026 Sep 9 18:eaea8773 Epub09/09/2026
