Generation of Functional CLL-Specific Cord Blood CTL Using CD40-Ligated CLL APC

William K Decker,John G Gribben,Nina Shah,Michael J Keating,Matthew M Halpert,Jeffrey J Molldrem,Simon N Robinson,Elizabeth J Shpall,Ruth Lapushin,William G Wierda,Dongxia Xing,Sufang Li,Hong Yang,Simrit Parmar,Hiroshi Shiku

doi:10.1371/journal.pone.0051390

William K Decker, John G Gribben + Show 13 more

Open Access

https://doi.org/10.1371/journal.pone.0051390

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Abstract

Though remissions have been observed following allo-HSCT for the treatment of CLL, many CLL patients are ineligible for transplant due to the lack of HLA-compatible donors. The use of umbilical cord blood (UCB) permits transplantation of many patients who lack HLA-compatible donors due to reduced requirements for stringent HLA matching between graft and recipient; however, disease relapse remains a concern with this modality. The generation of CLL-specific CTL from UCB T-cells, primed and expanded against the leukemic clone, might enhance the GVL effect and improve outcomes with UCB transplantation. Here we report the generation of functional, CLL-specific CTL using CD40-ligated CLL cells to prime partially-HLA matched UCB T-cells. Functionality and specificity were demonstrated by immune synapse assay, IFN-γ ELISpot, multi-parametric intracellular cytokine flow cytometry, and 51Cr release assay. The use of patient-specific, non-CLL controls demonstrated the generation of both alloantigen and CLL-specific responses. Subsequently, we developed a clinically-applicable procedure permitting separation of alloreactive CTL from leukemia-specific CTL. Leukemia-specific CTL were able to mediate in vivo killing of CLL in humanized mice without concurrent or subsequent development of xenoGVHD. Our results demonstrate that generation of CLL-specific effectors from UCB is feasible and practical, and the results support further exploration of this strategy as a treatment modality for CLL.

Highlights

B-cell chronic lymphocytic leukemia (CLL) is the most prevalent of the adult leukemias, accounting for at least 180,000 new diagnoses worldwide every year [1]
Transduced CLL cells were compared to both mock-transduced cells (PBS) and cells transduced with an irrelevant adenovector, neither of which demonstrated appreciable upregulation of CD95 or CD80 from baseline
The development of such effectors for active, specific immunotherapy of CLL might be significantly compromised by the ability of CLL cells to efficiently suppress T-cell mediated immune responses [20]–[][22]

Summary

Introduction

B-cell chronic lymphocytic leukemia (CLL) is the most prevalent of the adult leukemias, accounting for at least 180,000 new diagnoses worldwide every year [1]. While CLL is effectively treated with a variety of chemotherapeutic or antibody-based regimens, it is a chronic disease and cure is not achieved with conventional chemotherapy [2]. There is clear evidence that a graft versus leukemia (GVL) effect exists in CLL [3]; [4], and a number of studies have successfully demonstrated durable remissions following allogeneic hematopoietic stem cell transplantation (allo-HSCT) for poor-risk, relapsed, or refractory CLL [5]; [6]. In spite of successful outcomes following allo-HSCT, disease relapse remains a significant contributor to post-transplant mortality in patients with CLL. A number of strategies have been employed in an effort to amplify and perpetuate GVL in conjunction with alloHSCT including the use of rituximab [7], non-myeloablative reduced-intensity conditioning regimens, and donor lymphocyte infusion (DLI) [4]–[8]

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