Abstract

This Phase I/II dose-escalation trial evaluates ²¹¹At-BC8-B10 (an anti-CD45 α-particle–emitting monoclonal antibody) as a conditioning agent before haploidentical hematopoietic cell transplantation (HCT) for patients with relapsed or refractory high-risk acute leukemias and myelodysplastic syndromes (MDS). Eligible patients include those with AML, ALL, MPAL, or high-risk MDS (age 18–75 years). The preparative regimen consists of ²¹¹At-BC8-B10 (Day -8, dose-escalation), fludarabine (Days -6 to -2), cyclophosphamide (Days -6, -5), and total-body irradiation (Day -1), followed by PBSC or bone marrow infusion (Day 0). GVHD prophylaxis includes post-transplant cyclophosphamide (Days 3-4), mycophenolate mofetil (Days 5-35), and tacrolimus (Days 5-180). The primary endpoint is grades III/IV regimen-related toxicity to determine maximum tolerated dose. Secondary endpoints include remission achievement, engraftment rates, donor chimerism, non-relapse mortality, GVHD incidence, and overall/disease-free survival at 2 years. This approach combines the superior cytotoxic properties of α-particle therapy with haploidentical HCT’s immunologic advantages and PTCy-based GVHD prevention, offering the potential to improve outcomes in this patient population with otherwise poor prognosis.

Publication Information

Source: ClinicalTrials.gov

Trial Registration Date: September 14, 2018

Last Update Posted: October 16, 2025

Trial ID: NCT03670966

ClinicalTrials.gov Link: https://clinicaltrials.gov/study/NCT03670966

Authors

Sponsor: Fred Hutchinson Cancer Center

Principal Investigator: Phuong Vo, MD

Contact: Phone: 206-667-2749; Email: ptvo@fredhutch.org

Institutional Affiliation: Fred Hutch/University of Washington Cancer Consortium, Seattle, Washington, United States

Phase: Phase I/II

Estimated Enrollment: 30 patients

Study Timeline: July 10, 2019 – March 20, 2029 (estimated)

Funding: National Cancer Institute (NCI); NIH Grants P30CA015704 and P01CA078902