Background: Adoptive transfer of donor-derived EBV-specific T-cells (EBV-CTLs) can eradicate EBV associated lymphomas post hematopoietic cell (HCT) or solid organ (SOT) transplants but is not available for most patients. Methods: We developed a 3rd-party, allogeneic, off-the-shelf bank of 330 GMP grade EBV-CTL lines from specifically consented healthy HCT donors. We treated 46 recipients of HCT (N=33) or SOT (N=13) with established EBV associated lymphomas, who failed rituximab therapy, with 3rd-party EBV-CTLs. Treatment cycles consisted of 3 weekly infusions of EBV-CTLs and 3 weeks of observation. Results: The EBV-CTLs did not induce significant toxicities or graft injury. One patient developed grade I skin GVHD requiring topical therapy. Complete and sustained partial remissions were achieved in 68% of HCT recipients and 54% of SOT recipients. For patients who achieved CR/PR or stable disease after cycle 1, overall survival was 88.9% and 81.8% respectively at 1 year. Although only 1/11 patients (9.1%) with progression of disease (POD) after cycle 1 who received additional EBV-CTLs from the same donor survived, 3 of 5 with POD subsequently treated with EBV-CTLs from a different donor achieved CR or durable PR (60%) and survive > 1 year. Maximal responses were achieved after a median of 2 cycles. Conclusions: Third party EBV-CTLs of defined HLA restriction provide safe, immediately accessible treatment for EBV PTLD. Secondary treatment with EBV-CTLs restricted by a different HLA allele (switch therapy) can also induce remissions if initial EBV-CTLs are ineffective. These results suggest a promising potential therapy for patients with rituximab refractory EBV-associated lymphoma post transplant. Phase II protocols (NCT01498484 and NCT00002663) were approved by the Institutional Review Board at Memorial Sloan Kettering Cancer Center, Food and Drug Administration and National Marrow Donor Program. This work was supported through NIH grants CA23766, NIH R21CA162002, Aubrey Fund, The Claire Tow Foundation, Major Family Foundation, Max Cure Foundation, Richard “Rick” J. EIsemann Pediatric Research Fund, Banbury Foundation, Edith Robertson Foundation, Larry Smead Foundation. In June 2015 Atara Biotherapeutics licensed the EBV-CTL bank and is developing this as ATA-129.

Severe steroid-refractory acute graft-versus-host disease (aGVHD) is related to significant mortality and morbidity after allogeneic stem cell transplantation. Early clinical trials of therapy with human mesenchymal stem cells (hMSCs) in pediatric patients with severe aGVHD resistant to multiple immunosuppressive agents showed promising results. In this study, we evaluated the risk/benefit profile of remestemcel-L (Prochymal), a third-party, off-the-shelf source of hMSCs, as a rescue agent for treatment-resistant aGVHD in pediatric patients. Children with grade B-D aGVHD failing steroids and, in most cases, other immunosuppressive agents were eligible for enrollment. Patients received 8 biweekly i.v. infusions of 2 × 10(6) hMSCs/kg for 4 weeks, with an additional 4 weekly infusions after day +28 for patients who achieved either a partial or mixed response. The enrolled patients compose a very challenging population with severe disease that was nonresponsive to the standard of care, with 88% of the patients experiencing severe aGVHD (grade C or D). Seventy-five patients (median age, 8 yr; 58.7% male; and 61.3% Caucasian) were treated in this study. Sixty-four patients (85.3%) had received an unrelated hematopoietic stem cell graft, and 28 patients (37.3%) had received a cord blood graft. At baseline, the distribution of aGVHD grades B, C, and D was 12.0%, 28.0%, and 60.0%, respectively. The median duration of aGVHD before enrollment was 30 d (range, 2 to 1639 d), and patients failed a median of 3 immunosuppressive agents. Organ involvement at baseline was 86.7% gastrointestinal, 54.7% skin, and 36.0% liver. Thirty-six patients (48.0%) had 2 organs involved, and 11 patients (14.7%) had all 3 organs involved. When stratified by aGVHD grade at baseline, the rate of overall response (complete and partial response) at day +28 was 66.7% for aGVHD grade B, 76.2% for grade C, and 53.3% for grade D. Overall response for individual organs at day +28 was 58.5% for the gastrointestinal system, 75.6% for skin, and 44.4% for liver. Collectively, overall response at day +28 for patients treated for severe refractory aGVHD was 61.3%, and this response was correlated with statistically significant improved survival at day +100 after hMSC infusion. Patients who responded to therapy by day +28 had a higher Kaplan-Meier estimated probability of 100-d survival compared with patients who did not respond (78.1% versus 31.0%; P < .001). Prochymal infusions were generally well tolerated, with no evidence of ectopic tissue formation.

We conducted a phase I trial of allogeneic T cells sensitized in vitro against a pool of pentadecapeptides (15-mer peptides) spanning the sequence of CMVpp65 for adoptive therapy of 17 allogeneic hematopoietic cell transplant recipients with cytomegalovirus (CMV) viremia or clinical infection persisting despite prolonged treatment with antiviral drugs. All but 3 of the patients had received T cell-depleted transplants without graft-versus-host disease (GVHD) prophylaxis with immunosuppressive drugs after transplantation. The CMVpp65-specific T cells (CMVpp65CTLs) generated were oligoclonal and specific for only 1 to 3 epitopes, presented by a limited set of HLA class I or II alleles. T cell infusions were well tolerated without toxicity or GVHD. Of 17 patients treated with transplant donor (n = 16) or third-party (n = 1) CMVpp65CTLs, 15 cleared viremia, including 3 of 5 with overt disease. In responding patients, the CMVpp65CTLs infused consistently proliferated and could be detected by T cell receptor Vβ usage in CMVpp65/HLA tetramer + populations for period of 120 days to up to 2 years after infusion. Thus, CMVpp65CTLs generated in response to synthetic 15-mer peptides of CMVpp65 are safe and can clear persistent CMV infections in the post-transplantation period.

Background. Refractory CMV viremia and disease are associated with significant morbidity and mortality in recipients of hematopoietic stem cell transplant (HCT). Methods. In phase I/II trials, we treated 67 subjects for CMV viremia or disease arising after HCT with adoptive transfer of banked, third-party, CMVpp65-sensitized T cells (CMVpp65-VSTs). All were evaluable for toxicity and 59 for response. Evaluable subjects had CMV disease or persisting viremia that had failed at least 2 weeks of induction therapy with a median of 3 antiviral drugs; 84.7% had more than 3 of 11 high-risk features. CMVpp65-VSTs were specific for 1 to 3 CMVpp65 epitopes, presented by a limited set of HLA class I or II alleles, and were selected based on high-resolution HLA matching at 2 of 10 HLA alleles and matching for subject and subject’s HCT donor for 1 or more alleles through which the CMVpp65-VSTs were restricted. Results. T cell infusions were well tolerated. Of 59 subjects evaluable for response, 38 (64%) achieved complete or durable partial responses. Conclusions. Recipients responding to CMVpp65VSTs experienced an improved overall survival. Of the risk factors evaluated, transplant type, recipient CD4⁺ and CD8⁺ T cell levels prior to adoptive therapy, and the HLA restriction of CMVpp65-VSTs infused each significantly affected responses. In addition, CMVpp65-specific T cells of HCT donor or recipient origin contributed to the durability of both complete and partial responses. Trial Registration. NCT00674648; NCT01646645; NCT02136797 (NIH). Funding. NIH (P01 CA23766, R21 CA162002 and P30 CA008748); Aubrey Fund; Claire Tow Foundation; Major Family Foundation; “Rick” Eisemann Pediatric Research Fund; Banbury Foundation; Edith Robertson Foundation; Larry Smead Foundation.