Abstract
ObjectivesA diverse intratumoral T‐cell receptor (TCR) repertoire is associated with improved survival in diffuse large B‐cell lymphoma (DLBCL) treated with rituximab/cyclophosphamide/doxorubicin/prednisolone/vincristine (R‐CHOP) chemoimmunotherapy. We explored the impact of intratumoral TCR repertoire on interim PET (iPET) done after four cycles of R‐CHOP, the relationships between intratumoral and circulating repertoire, and the phenotypes of expanded clonotypes.MethodsWe sequenced the third complementarity‐determining region of TCRβ in tumor samples, blood at pre‐therapy and after four cycles of R‐CHOP in 35 patients enrolled in ALLGNHL21 trial in high‐risk DLBCL. We correlated the TCR diversity metrics with iPET status, gene expression profiles and HLA‐class I genotypes. We then sequenced the FACS‐sorted peripheral blood T cells in six patients, and pentamer‐sorted EBV‐specific CD8+ T cells in one patient from this cohort.ResultsCompared with iPET− patients, the intratumoral TCR repertoire in iPET+ patients was characterised by higher cumulative frequency of abundant clonotypes and higher productive clonality. There was a variable overlap between circulating and intratumoral repertoires, with the dominant intratumoral clonotypes more likely to be detected in the blood. The majority of shared clonotypes were CD8+ PD‐1HI T cells, and CD8+ T cells had the largest clonal expansions in tumor and blood. In a patient with EBV+ DLBCL, EBV‐specific intratumoral clonotypes were trackable in the blood.ConclusionThis study demonstrates that clonally expanded intratumoral TCR repertoires are associated with iPET+ and that the blood can be used to track tumor‐associated antigen‐specific clonotypes. These findings assist the rationale design and therapeutic monitoring of immunotherapeutic strategies in DLBCL.
Highlights
Diffuse large B-cell lymphoma (DLCBL) is the commonest aggressive B-cell lymphoma
It has previously been demonstrated that infiltration of CD4+ and CD8+ T cells within the tumor microenvironment (TME) is strongly predictive of improved outcomes to initial rituximab/cyclophosphamide/doxorubicin-prednisolone/ vincristine (R-CHOP) chemoimmunotherapy.[7,8,9,10,11,12]
Our previous work had focused on the T-cell receptor (TCR) repertoire in the tumor tissue, whereas the current study investigated TCR repertoire in tumor and tracked the intratumoral clonotypes (ITC) in sequential blood samples during treatment with R-CHOP
Summary
Diffuse large B-cell lymphoma (DLCBL) is the commonest aggressive B-cell lymphoma. Diffuse large B-cell lymphoma employs a variety of immune evasion strategies associated with poor outcomes. These include the loss of antigen presentation molecules on the tumor cells and the facilitation of a tumor microenvironment (TME) that prevents effective tumor eradication.[4,5,6] On account of these evasion strategies, T-cell responses appear to play a critical role in determining the outcomes of the frontline treatment. It has previously been demonstrated that infiltration of CD4+ and CD8+ T cells within the TME is strongly predictive of improved outcomes to initial rituximab/cyclophosphamide/doxorubicin-prednisolone/ vincristine (R-CHOP) chemoimmunotherapy.[7,8,9,10,11,12] the clonal structures and phenotypes of these intratumoral T cells in DLBCL are currently unknown
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