Cyclophosphamide treatment induces rejection of established P815 mastocytoma by enhancing CD4 priming and intratumoral infiltration of P1E/H‐2K^d‐specific CD8⁺ T cells

Abstract

There is increasing evidence that the effect of chemotherapy on tumor growth is not cell autonomous but relies on the immune system. The objective of this study was therefore to decipher the cellular and molecular mechanisms underlying the role of innate and adaptive immunity in chemotherapy-induced tumor rejection. Treatment of DBA/2 mice bearing P815 mastocytoma with cyclophosphamide induced rejection and long-term protection in a CD4-and CD8-dependent manner. A population of inflammatory-type dendritic cells was dramatically expanded in the lymph nodes of mice that rejected the tumor and correlated with CD4-dependent infiltration, in tumor bed, of tumor-specific CD8 1 T lymphocytes. Our data point to a major role of CD4 1 T cells in inducing chemokine expression in the tumor, provoking migration of tumor-specific CXCR3 1 CD8 1 T lymphocytes. Importantly, the analysis of CD8 1 T cells specific to P1A/H-2L d and P1E/H-2K d revealed that cyclophosphamide altered the P815-specific CD8 T repertoire by amplifying the response specific to the mutated P1E antigen.Increasing evidence suggests that tumor infiltration by T lymphocytes is a good prognostic factor for cancer patients. The prognostic and predictive impact of the immune infiltrates has been demonstrated in colorectal, ovarian, breast cancers and melanomas.

Cyclophosphamide treatment regulates the balance of functional/exhausted tumor-specific CD8+T cells

“…It is noteworthy that the infiltration of (P1E/H-2K d ) C effector cells into regressing tumors correlated with an enhanced proportion of (P1E/H-2K d ) C CXCR3 C CD62L ¡ cells in the draining LNs, a phenotype of effector cells ready to home to peripheral inflammatory sites. The efficient immune response induced by cyclophosphamide treatment probably results from combined effects, linked to lymphopenia and inflammation, such as (i) immunogenic death of tumor cells (enhancing tumor antigen presentation); (ii) increased number of inflammatory monocytes; (iii) apoptosis of antigen-specific exhausted lymphocytes in tumor bed (which are barely detectable until day 7 after treatment, not depicted); (iv) increased proliferation of tumor-specific lymphocytes in tumor and draining LNs; (v) expression of chemokines within the tumor, favoring the recruitment of activated (CXCR3 C CD62L ¡ ) P1E-specific T cells (this report and 11 ). An interesting hypothesis would be a direct effect of cyclophosphamide on T cells displaying different sensitivity to the apoptotic effect of cyclophosphamide.…”

“…We have shown previously that a single injection of CTX rendered 100% of mice resistant to a second lethal injection of P815. 11 Of note, a recent study by Wherry and colleagues indicates that T cells re-invigorated after PD-1 blockade became re-exhausted and failed to become memory T cells, due to epigenetic stability. 35 Whether CTX programs tumor-specific cells into effector as well as memory cells is presently unclear and requires further investigation.…”

“…The proportion of these cells, which recognize the P1E/H-2K d complex increased from approximately 30% to over 50% of CD8 C T lymphocytes, whereas the proportion of CD8 C T cells specific for the MAGE-type antigen P1A (encoded by the cancer-germline gene P1A) in the context of H-2L d decreased concomitantly, indicating that cyclophosphamide altered the repertoire of CD8 C T cells recognizing tumor antigens. 11 We monitored the expression of selected genes expressed by P1E-specific CD8 C T cells infiltrating progressing vs. regressing (after cyclophosphamide) P815 tumors. Single cell PCR (polymerase chain reaction) and flow cytometry analyses revealed that administration of cyclophosphamide favored the development of effector cells with strong cytotoxic capacity, suggesting that chemotherapy treatment may remodel the quality and/or effector activity of tumor-specific CD8 C T cells.…”

L’immunothérapie au service de la chimiothérapie, de nouvelles avancées

“…Elle requiert d'une part, l'expression du récepteur CXCR3 (C-X-C chemokine receptor type 3) par les lymphocytes T CD8 + et, d'autre part, la présence de lymphocytes T auxiliaires CD4 + . Bien que le mécanisme initiant la synthèse des chimiokines ne soit pas élucidé, l'augmentation de leur production pourrait être reliée à une réaction inflammatoire impliquant les lymphocytes T CD4 + [9]. 4.…”

High-dose cyclophosphamide induces specific tumor immunity with concomitant recruitment of LAMP1/CD107a-expressing CD4-positive T cells into tumor sites

“…Recent observations have suggested that a single high -dose of CTX can induce specific tumor immunity [11]. Hence, we examined the effects of a single high -dose of CTX on the tumors arising from subcutaneous injection of a mouse hepatoma cell line.…”