TY - JOUR
T1 - Impact of CD4 T cells on intratumoral CD8 T-cell exhaustion and responsiveness to PD-1 blockade therapy in mouse brain tumors
AU - Khan, Saad M.
AU - Desai, Rupen
AU - Coxon, Andrew
AU - Livingstone, Alexandra
AU - Dunn, Gavin P.
AU - Petti, Allegra
AU - Johanns, Tanner M.
N1 - Publisher Copyright:
© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.
PY - 2022/12/1
Y1 - 2022/12/1
N2 - BACKGROUND: Glioblastoma is a fatal disease despite aggressive multimodal therapy. PD-1 blockade, a therapy that reinvigorates hypofunctional exhausted CD8 T cells (Tex) in many malignancies, has not shown efficacy in glioblastoma. Loss of CD4 T cells can lead to an exhausted CD8 T-cell phenotype, and terminally exhausted CD8 T cells (Texterm) do not respond to PD-1 blockade. GL261 and CT2A are complementary orthotopic models of glioblastoma. GL261 has a functional CD4 T-cell compartment and is responsive to PD-1 blockade; notably, CD4 depletion abrogates this survival benefit. CT2A is composed of dysfunctional CD4 T cells and is PD-1 blockade unresponsive. We leverage these models to understand the impact of CD4 T cells on CD8 T-cell exhaustion and PD-1 blockade sensitivity in glioblastoma. METHODS: Single-cell RNA sequencing was performed on flow sorted tumor-infiltrating lymphocytes from female C57/BL6 mice implanted with each model, with and without PD-1 blockade therapy. CD8+ and CD4+ T cells were identified and separately analyzed. Survival analyses were performed comparing PD-1 blockade therapy, CD40 agonist or combinatorial therapy. RESULTS: The CD8 T-cell compartment of the models is composed of heterogenous CD8 Tex subsets, including progenitor exhausted CD8 T cells (Texprog), intermediate Tex, proliferating Tex, and Texterm. GL261 is enriched with the PD-1 responsive Texprog subset relative to the CT2A and CD4-depleted GL261 models, which are composed predominantly of the PD-1 blockade refractory Texterm subset. Analysis of the CD4 T-cell compartments revealed that the CT2A microenvironment is enriched with a suppressive Treg subset and an effector CD4 T-cell subset that expresses an inhibitory interferon-stimulated (Isc) signature. Finally, we demonstrate that addition of CD40 agonist to PD-1 blockade therapy improves survival in CT2A tumor-bearing mice. CONCLUSIONS: Here, we describe that dysfunctional CD4 T cells are associated with terminal CD8 T-cell exhaustion, suggesting CD4 T cells impact PD-1 blockade efficacy by controlling the severity of exhaustion. Given that CD4 lymphopenia is frequently observed in patients with glioblastoma, this may represent a basis for resistance to PD-1 blockade. We demonstrate that CD40 agonism may circumvent a dysfunctional CD4 compartment to improve PD-1 blockade responsiveness, supporting a novel synergistic immunotherapeutic approach.
AB - BACKGROUND: Glioblastoma is a fatal disease despite aggressive multimodal therapy. PD-1 blockade, a therapy that reinvigorates hypofunctional exhausted CD8 T cells (Tex) in many malignancies, has not shown efficacy in glioblastoma. Loss of CD4 T cells can lead to an exhausted CD8 T-cell phenotype, and terminally exhausted CD8 T cells (Texterm) do not respond to PD-1 blockade. GL261 and CT2A are complementary orthotopic models of glioblastoma. GL261 has a functional CD4 T-cell compartment and is responsive to PD-1 blockade; notably, CD4 depletion abrogates this survival benefit. CT2A is composed of dysfunctional CD4 T cells and is PD-1 blockade unresponsive. We leverage these models to understand the impact of CD4 T cells on CD8 T-cell exhaustion and PD-1 blockade sensitivity in glioblastoma. METHODS: Single-cell RNA sequencing was performed on flow sorted tumor-infiltrating lymphocytes from female C57/BL6 mice implanted with each model, with and without PD-1 blockade therapy. CD8+ and CD4+ T cells were identified and separately analyzed. Survival analyses were performed comparing PD-1 blockade therapy, CD40 agonist or combinatorial therapy. RESULTS: The CD8 T-cell compartment of the models is composed of heterogenous CD8 Tex subsets, including progenitor exhausted CD8 T cells (Texprog), intermediate Tex, proliferating Tex, and Texterm. GL261 is enriched with the PD-1 responsive Texprog subset relative to the CT2A and CD4-depleted GL261 models, which are composed predominantly of the PD-1 blockade refractory Texterm subset. Analysis of the CD4 T-cell compartments revealed that the CT2A microenvironment is enriched with a suppressive Treg subset and an effector CD4 T-cell subset that expresses an inhibitory interferon-stimulated (Isc) signature. Finally, we demonstrate that addition of CD40 agonist to PD-1 blockade therapy improves survival in CT2A tumor-bearing mice. CONCLUSIONS: Here, we describe that dysfunctional CD4 T cells are associated with terminal CD8 T-cell exhaustion, suggesting CD4 T cells impact PD-1 blockade efficacy by controlling the severity of exhaustion. Given that CD4 lymphopenia is frequently observed in patients with glioblastoma, this may represent a basis for resistance to PD-1 blockade. We demonstrate that CD40 agonism may circumvent a dysfunctional CD4 compartment to improve PD-1 blockade responsiveness, supporting a novel synergistic immunotherapeutic approach.
KW - CD4-positive T-lymphocytes
KW - CD8-positive T-lymphocytes
KW - brain neoplasms
KW - immunotherapy
KW - lymphocytes, tumor-infiltrating
UR - http://www.scopus.com/inward/record.url?scp=85144595104&partnerID=8YFLogxK
U2 - 10.1136/jitc-2022-005293
DO - 10.1136/jitc-2022-005293
M3 - Article
C2 - 36543376
AN - SCOPUS:85144595104
SN - 2051-1426
VL - 10
JO - Journal for ImmunoTherapy of Cancer
JF - Journal for ImmunoTherapy of Cancer
IS - 12
ER -