Low-dose interleukin-2 (IL-2) therapy for chronic graft-versus-host disease (cGVHD) generates a rapid rise in plasma IL-2 levels and CD41CD251CD1272Foxp31 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 3 106 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 5 .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.
Bibliographical noteFunding Information:
Tensha Therapeutics, Otsuka, and Sigma Ta and consulting fees from Bristol-Myers Squibb, Merck, Infinity Pharmaceuticals, Pfizer, and Affimed. J.R. reports research funding from Equillium and Kite Pharma; and consulting income from Aleta Biotherapeutics, AVROBIO, Cel-gene, Draper Laboratory, LifeVault Bio, Talaris Therapeutics, and TScan Therapeutics. B.R.B. has received consulting fees from Kamon Pharmaceuticals, Five Prime Therapeutics, Regeneron Pharmaceuticals, Magenta Therapeutics, and BlueRock Therapeutics; research support from Fate Therapeutics, RXi Pharmaceuticals, Alpine Immune Sciences, AbbVie, the Leukemia and Lymphoma Society, the Children’s Cancer Research Fund, and the Kids First Fund; and is a cofounder of Tmunity Therapeutics. R.J.S. serves on the Board of Directors for Kiadis Pharma, is on the data safety monitoring board for Juno Therapeutics, and has received consulting fees from Cugene, Jazz Pharmaceuticals, Neovii, Gilead Sciences, and Mana Therapeutics. The remaining authors declare no competing financial interests.
Conflict-of-interest disclosure: J.K. has received research funding from Prometheus Laboratories, Millennium Pharmaceuticals, and Miltenyi Biotec; consulting fees from Amgen, Equillium, and Fortress Biotech; and advisory board fees from Takeda Pharmaceuticals, Cugene, and Kadmon. P.A. has received research funding from Bristol-Myers Squibb, Merck, Affimed, Adaptive, Roche,
This work was supported by National Institutes of Health, National Cancer Institute grants R01CA183559, R01CA183560, and P01CA142106; Prometheus Laboratories Inc.; the Mooney Family Initiative for Translational and Clinical Studies in Rare Diseases; an American Society of Hematology Junior Faculty Scholar Award; and the Ted & Eileen Pasquarello Research Fund.