Facilitating Resolution of Life-Threatening Acute Graft-Versus-Host Disease By Supplementation of Human Chorionic Gonadotropin and Epidermal Growth Factor (Pregnyl): A Phase I Study

INTRODUCTION: Patients with severe acute graft-versus-host disease (aGVHD) are at high risk of death due to damaged organs and tissues. We have previously shown that severe aGVHD is characterized by an imbalance of circulating tissue repair factors, with elevated amphiregulin (AREG) and very low (<10 pg/ml) plasma epidermal growth factor (EGF). We hypothesized that giving supplemental EGF, contained in an inexpensive, commercially available drug (urinary-derived human chorionic gonadotropin [hCG], Pregnyl®) in addition to standard aGVHD therapy would improve outcomes. HCG has well-known immunomodulatory properties, including shifting the balance of T cells toward a regulatory (Treg) phenotype that could also be beneficial in severe aGVHD. Therefore, we tested the use of hCG/EGF in patients with Minnesota High Risk and steroid dependent or refractory aGVHD to enhance both hCG-mediated immunologic tolerance and tissue repair via supplemental EGF in a phase I study.

PATIENTS AND METHODS: Twenty-six patients received hCG/EGF in addition to standard aGVHD therapy. We treated 13 patients with onset Minnesota High Risk aGVHD with high-dose steroids (methylprednisolone 48 mg/m²) plus subcutaneous (SQ) injections of hCG/EGF every other day for 7 days. In the 2^nd line therapy cohort, we treated 13 patients with hCG/EGF SQ every other day for 14 days, recognizing the time to response may be longer in this cohort relative to those with onset aGVHD, along with increased steroids (steroid dependent, N=5) and intensified immune suppression (steroid refractory, N=8). We then assessed response after 7 days in High Risk aGVHD and after 14 days in steroid dependent/refractory aGVHD. In both cohorts, patients with a complete or partial response (CR/PR) at the end of the initial dosing period were eligible to receive maintenance hCG/EGF SQ twice weekly for up to 5 weeks, whereas patients with no response (NR) received no further study drug doses and received best available therapy from their treating physicians. Initial hCG dosing was at 500 units hCG/m² SQ, escalating to 2,000 units hCG/m² in cohorts of 2, with dose assignment by the continual reassessment method. We analyzed GVHD-associated plasma biomarkers and enumerated circulating CD4+FoxP3+CD127- Tregs and CD8+ T lymphocytes during therapy.

RESULTS: HCG/EGF was well tolerated, with no dose-limiting toxicities. The median EGF dose was 50,833 pg/ml. The most common treatment emergent side effect was edema (N=16, 62%). At day 28 of study, responses for initial therapy were 8/13 CR (62%), 0/13 PR (0%), and 5/13 NR (38%), higher than institutional historical (n=269) 26% CR, 16% PR, 57% NR (Figure 1A). Responses for 2^nd line therapy were 7/13 CR (54%), 1/13 PR (8%), 5/13 NR (38%), 4 of which were deaths (31%), improved relative to historical outcomes (n=85) of 18% CR, 19% PR, 63% NR (including 16% deaths, Figure 1A). Cytopenias were not worse during hCG/EGF; responders had a slight leukocytosis (day 7 median white blood cells [WBC] 9.7 x 10⁹/L), returning to baseline (WBC 5.8 x 10⁹/L, p=0.015) by day 56. Patients had increases in serum hCG (median 1.5 vs 138 IU/L, p<0.001), estradiol (median 12 vs 36 pg/ml, p=0.003), and testosterone (median 106 vs 450 ng/dl, p=0.01) from baseline to day 7; all returned to baseline by day 56. In initial therapy patients, plasma EGF rose from baseline 3 pg/ml to 25.4 pg/ml at 6 hours post-hCG/EGF dose (p=0.02); while in 2^nd line patients, plasma EGF never rose from baseline 5 pg/ml. Treg expansion peaked at 131% of baseline at day 7 in Arm 1, and 145% of baseline at day 14 in Arm 2. Patients with a day 28 CR/PR had a higher median Treg/CD8 ratio at day 28 (0.11 vs 0.01, p=0.03) and a 4.6-fold reduction in plasma AREG over time (baseline median 99.6 pg/ml to 21.8 pg/ml at day 56, p=0.006, Figure 1B).

CONCLUSIONS: HCG/EGF is a novel and well-tolerated adjunct therapy in high-risk and steroid-dependent/refractory aGVHD, associated with minimal toxicity and encouraging response rates. The mechanisms of benefit may include immunomodulation via Treg expansion despite high-dose steroids and facilitation of tissue repair with detectable increases in circulating EGF. The optimal dose and duration of hCG/EGF are under investigation, with ongoing dose escalation in patients with steroid-refractory aGVHD based upon these initial results. Decreasing plasma AREG over time may reflect successful treatment of life-threatening aGVHD.

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