A phase 1 study of donor regulatory T-cell infusion plus low-dose interleukin-2 for steroid-refractory chronic graft-vs-host disease.

Chronic graft-versus-host disease (cGVHD) remains a frequent cause of nonrelapse morbidity and mortality after allogeneic hematopoietic stem cell transplantation. Despite recent advances, options for steroid-refractory (SR) cGVHD are limited. In previous trials of low-dose interleukin-2 (LD IL-2), the immunomodulatory properties of regulatory T cells (Tregs) have been harnessed to treat SR-cGVHD safely and effectively. In the present study, we combined a single infusion of Treg-enriched lymphocytes (Treg DLI) from the original stem cell donor with in vivo Treg expansion using LD IL-2 (1 × 106 IU/m2 per day for 8 weeks) in 25 adult patients with SR-cGVHD. Treg were not expanded ex vivo. Treg DLI was initiated at 0.1 × 106 cells per kg patient and escalated to a maximum dose of 1 × 106 cells per kg. Treg DLI plus LD IL-2 was well tolerated and led to partial responses (PR) in 5 of 25 patients (20%) after 8 weeks of therapy. Ten additional patients (40%) had stable disease with minor responses not meeting PR criteria. Patients at all dose levels had similar Treg expansion without significant changes in CD4+ conventional T cells or CD8+ T cells. High-throughput sequencing of the T-cell receptor ß locus showed selective improvement of Treg diversity. A subset of DLI-derived Treg clones showed preferential expansion at week 8 and long-term persistence 1-year postinfusion. We demonstrate for the first time that infusion of polyclonal healthy donor Tregs followed by expansion with LD IL-2 is safe in patients with SR-cGVHD, thus establishing a foundation for future adoptive Treg therapies in the posttransplant setting. This trial was registered at www.clinicaltrials.gov as #NCT01937468.

Allogeneic hematopoietic cell transplantation after prior targeted therapy for high-risk chronic lymphocytic leukemia.

Allogeneic hematopoietic cell transplantation (alloHCT) can cure previously treated high-risk chronic lymphocytic leukemia (CLL) patients if they are suitable for transplant through the graft-versus-leukemia effect. However, since the emergence of targeted therapies, the role of alloHCT for high-risk CLL is less clear. To address this question, we evaluated 108 high-risk CLL patients who underwent alloHCT from 2010 to 2018. Thirty patients from the period of 2013 to 2018 received targeted therapy prior to alloHCT. The median age for the targeted therapy cohort was 60 years (range, 30-71 years), and 20% and 73% had complete and partial remission, respectively: 76% had del(17p), 46.2% had 5 or more cytogenetic abnormalities, and 78.9% were IGHV unmutated. The median number of prior therapies was 4 (range, 1-9). With a median follow-up time of 36 months (range, 10-72 months), the 3-year overall (OS) and progression-free survival (PFS) were 87% and 69%, respectively. The 3-year cumulative incidence of nonrelapse mortality and relapse was 7% and 24%, respectively. For the control cohort of 78 patients who underwent alloHCT from 2010 to 2014 and received only chemoimmunotherapy prior to transplant, the 3-year OS and PFS were 69% and 58%, respectively. Patients treated with targeted therapy prior to alloHCT had a significantly higher number of circulating T and B cells and a lower ratio of CD4 regulatory T cells to CD4 conventional T cells early after transplant. In summary, despite multiple high-risk features, the clinical outcome of CLL patients who receive targeted therapy prior to transplant is excellent and alloHCT should be offered while the disease is under control.

Dose-escalated interleukin-2 therapy for refractory chronic graft-versus-host disease in adults and children.

Low-dose interleukin-2 (IL-2) therapy for chronic graft-versus-host disease (cGVHD) generates a rapid rise in plasma IL-2 levels and CD4+CD25+CD127-Foxp3+ regulatory T-cell (CD4Treg) proliferation, but both decrease over time despite continued daily administration. To test whether IL-2 dose escalation at the time of anticipated falls in plasma levels could circumvent tachyphylaxis and enhance CD4Treg expansion, we conducted a phase 1 trial in 10 adult and 11 pediatric patients with steroid-refractory cGVHD (www.clinicaltrials.gov: NCT02318082). Daily IL-2 was initiated in children and adults (0.33 × 106 and 0.67 × 106 IU/m2 per day, respectively). Dose escalations were scheduled at weeks 2 and 4 to a maximum dose of 1 × 106 IU/m2 per day in children and 2 × 106 IU/m2 per day in adults. Patients continued at their maximum tolerated dose (MTD) until week 8. Children tolerated IL-2 dose escalation with partial responses (PRs) in 9 of 11 patients (82%) at multiple cGVHD sites, including lung. Patient-reported outcome scores for skin and lung improved significantly in pediatric patients. In contrast, 5 of 10 adults required dose reduction, and only 2 of 7 evaluable patients (29%) had PRs at week 8. CD4Tregs and natural killer cells expanded in both cohorts without significant changes in conventional CD4+ T cells (Tcons) or CD8+ T cells. Children achieved a higher median CD4Treg/Tcon ratio at week 8 (0.4 vs 0.18, P = .02) despite lower IL-2 doses. We show for the first time that low-dose IL-2 is safe and effective in children with advanced cGVHD. In adults, escalation above the previously defined MTD did not improve CD4Treg expansion or clinical response.