First-in-child phase I trial of p-STAT3 inhibitor WP1066 in pediatric brain tumor patients
Robert C. Castellino, Hope Mumme, Andrea Franson, Bing Yu, Hope Robinson, Kavita Dhodapkar, Dolly Aguilera, Matthew Schniederjan, Rohali Keesari, Zhulin He, Manoj Bhasin, Waldemar Priebe, Amy B. Heimberger, Tobey J. MacDonald
Robert C. Castellino, Hope Mumme, Andrea Franson, Bing Yu, Hope Robinson, Kavita Dhodapkar, Dolly Aguilera, Matthew Schniederjan, Rohali Keesari, Zhulin He, Manoj Bhasin, Waldemar Priebe, Amy B. Heimberger, Tobey J. MacDonald
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Clinical Research and Public Health Clinical Research Oncology

First-in-child phase I trial of p-STAT3 inhibitor WP1066 in pediatric brain tumor patients

Abstract

BACKGROUND WP1066 is an orally bioavailable, small-molecule inhibitor of activated phosphorylated STAT3 (p-STAT3) that has demonstrated preclinical efficacy in pediatric brain tumor models.METHODS In a first-in-child, single-center, single-arm 3+3 design phase I clinical trial, 10 patients were treated with WP1066 twice daily, Monday-Wednesday-Friday, for 14 days of each 28-day cycle to determine the maximum tolerated dose/maximum feasible dose of WP1066. Compassionate-use treatment with WP1066 in 3 pediatric patients with H3.3G34R/V-mutant high-grade glioma (HGG) is also described.RESULTS There was no significant toxicity, and the maximum feasible dose (MFD) was determined to be 8 mg/kg. Treatment-related adverse events were grade 1–2 (diarrhea and nausea most common); there were no dose-limiting toxicities. Median progression-free and overall survival was 1.8 months and 4.9 months, respectively. One partial response was observed in a patient with pontine glioma. Among the H3.3G34R/V-mutant HGG patients not on study, WP1066 was administered after upfront radiation to one patient for 17 months. At all dose levels tested, WP1066 suppressed p-STAT3 expression by peripheral blood mononuclear cells (PBMCs). Single-cell RNA sequencing analysis of PBMCs demonstrated increased CD4+ and CD8+ T cells, proinflammatory TNFA signaling, differentiation activity in myeloid cells, and downregulation of Tregs after WP1066 treatment, consistent with systemically inhibited STAT3 activity.CONCLUSION WP1066 is safe, has minimal toxicity, and induces antitumor immune responses in pediatric brain tumor patients. Phase II investigation of WP1066 at the MFD in this patient population is warranted.TRIAL REGISTRATION ClinicalTrials.gov NCT04334863.FUNDING CURE Childhood Cancer and Peach Bowl Inc.

Authors

Robert C. Castellino, Hope Mumme, Andrea Franson, Bing Yu, Hope Robinson, Kavita Dhodapkar, Dolly Aguilera, Matthew Schniederjan, Rohali Keesari, Zhulin He, Manoj Bhasin, Waldemar Priebe, Amy B. Heimberger, Tobey J. MacDonald

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Figure 3

Radiographic tumor response to WP1066 treatment.

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Radiographic tumor response to WP1066 treatment. Serial brain MRIs from ...
Serial brain MRIs from a pediatric patient with progressive DIPG (AflacST1901-01) who had completed a 2-week course of palliative focal re-irradiation to the tumor 12 weeks before starting study treatment show 33.8% reduction in tumor volume after 2 cycles of WP1066 treatment compared with baseline MRI obtained 2 days before the start of study treatment (15.48 cm3 to 10.25 cm3). The patient was successfully tapered off high-dose corticosteroids and improved clinically, from being wheelchair bound to walking with assistance. Subsequent brain MRI performed after 3 cycles of WP1066 while off steroids for 4 weeks (pre–cycle 4) showed a 61.8% increase in tumor volume from baseline (25.05 cm3), but no increase in intratumoral blood perfusion, suggesting that the increase in tumor volume was due to treatment-related changes. Because of the increase in tumor volume, the patient was taken off protocol therapy per the study guidelines; however, the patient continued to exhibit clinical improvement followed by stability for an additional 6 months.