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

Abstract

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.

Conflict of interest statement

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, 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, Celgene, 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.

© 2019 by The American Society of Hematology.

Figures

Graphical abstract

Figure 1.

Study design and clinical response. (A) Study design. (B) Skin, gastrointestinal (GI), joint/muscle/fascia (JMF), lung, liver, mouth, and eye cGVHD scores at baseline (W0) and at week 8 (W8). *Oral and ocular sites were not included in determination of response, because additional topical therapy was permitted for those sites. GSS, global severity score; NE, not evaluable; PD, progressive disease; SD, stable disease.

Figure 2.

Patient reported outcomes (Lee cGVHD Symptom Scale). Paired pre- to posttreatment analysis for “Skin” and “Breathing” subscales in the pediatric (A) and adult (B) cohorts. Each line represents an individual patient’s data at baseline and at week 8. W0, baseline (pretreatment); W8, week 8 (posttreatment).

Figure 3.

Sclerotic skin response and change in corticosteroid doses over time in pediatric patients. (A) Sclerodermatous cGVHD of the skin in a pediatric patient (patient 16) at baseline and after 8 weeks and 6 months of low-dose IL-2 therapy. There was complete resolution of sclerotic skin by 6 months, although residual hyperpigmentation of the skin remained. Patient 1 (not shown) also had a similar skin response. (B) Change in daily corticosteroid doses (mg/kg) for pediatric patients at baseline, 6 months (6MO), and 1 year (1Y) of IL-2 therapy. Each line represents an individual patient over time.

Figure 4.

Plasma IL-2 levels and fold change in absolute CD4Treg numbers during IL-2 therapy. (A) Pediatric cohort. (B) Adult cohort. Blue lines denote plasma IL-2 concentrations (pg/mL), red lines denote fold change (FC) in absolute CD4Treg count from baseline (W0). Median values (circles) and the IQR (whisker bars) are shown at each time point. The number of patients evaluated at each time point is indicated below.

Figure 5.

Immunologic impact of low-dose IL-2 on lymphocytes. (A) CD4Treg/Tcon ratio for the pediatric and adult cohorts. (B) Fold change in absolute CD8 T-cell and NK cell counts for the pediatric and adult cohorts. (C) Recent thymic emigrant (RTE) CD4Tregs shown as a percentage of the naive CD4Treg population for the pediatric and adult cohorts. Median values (circles) and the IQR (whisker bars) are shown at each time point. The number of patients evaluated at each time point is indicated at the bottom. *P < .05 pediatric vs adult, Wilcoxon rank-sum test.

Figure 6.

Expression of BCL-2 and PD-1 in CD4Tregs in pediatric and adult patients. (A) BCL-2 mean fluorescence intensity (MFI) in CM CD4Tregs at baseline (W0) and at weeks 2, 4, and 8 of IL-2 therapy. (B) Percentage of CM CD4Tregs with PD-1 expression. Box plots depict the 75th percentile, median, and 25th percentile values; whiskers represent maximum and minimum values, except for outliers. Blue, pediatric cohort. Red, adult cohort. The number of patients evaluated at each time point is indicated at the bottom. *P < .05, **P < .005 pediatric vs adult, Wilcoxon rank-sum test.

Figure 7.

CD4Treg TCRβ repertoire analysis in pediatric patients. (A) Hill-based diversity values for CD4Tregs from patients 1, 6, 11, and 12 at baseline, W8 or W16, and 6 months of IL-2 therapy. Each line represents an individual patient over time. (B) Correlation coefficients between the productive frequencies of the top 1000 clones at weeks 8 or 16 and the productive frequencies of the same clones at baseline for each cell type are shown for the 4 pediatric patients. (C) Number of clonotypes making up the top 20% of productive frequencies at baseline and after 8 to 16 weeks of IL-2 therapy. Each box within the large squares represents a unique clonotype, and the box size represents the relative proportion of that clonotype. Colors at baseline and W8-W16 do not represent the same clonotype. *P < .05, 2-sided Wilcoxon signed-rank test.