A single-arm prospective phase I trial of 68Ga-PFBC01 PET/CT for multiple myeloma B cell maturation antigen imaging

BACKGROUND: B cell maturation antigen (BCMA) is a key therapeutic target in multiple myeloma (MM), yet its whole-body in vivo distribution and role in disease assessment remain incompletely defined. We aimed to evaluate the safety, diagnostic performance, and clinical utility of a novel BCMA-targeted PET tracer, 68Ga-PFBC01, in patients with plasma cell disorders. METHODS: We conducted a single-center, prospective, single-arm phase I trial (ClinicalTrials.gov NCT06717113). Fifty patients underwent 68Ga-PFBC01 PET/CT, including 40 with paired 18F-FDG PET/CT for head-to-head comparison. Primary outcomes included diagnostic performance (sensitivity, specificity, PPV, NPV, and inter-reader agreement). Secondary outcomes included correlations with clinical biomarkers, treatment response assessment, impact on clinical decision-making, and safety. RESULTS: 68Ga-PFBC01 PET/CT demonstrated superior diagnostic performance compared with 18F-FDG PET/CT (sensitivity 96.9% vs 84.6%; specificity 71.4% vs 60.0%). Quantitative PET-derived tumor burden correlated with M protein (R = 0.325, P = 0.026), free light chains (R = 0.340-0.437, P ≤ 0.015), soluble BCMA (R = 0.433, P = 0.050), and bone marrow plasma cells (R = 0.682, P < 0.001). Imaging findings altered clinical management in multiple cases, enabling both therapy escalation and de-escalation. Blood-pool uptake strongly correlated with soluble BCMA (R = 0.899, P < 0.001) and overall disease burden (R = 0.736, P < 0.001). No serious tracer-related adverse events were observed; two patients (4%) experienced mild events. CONCLUSION: 68Ga-PFBC01 PET/CT provides biologically specific, whole-body assessment of MM, outperforming 18F-FDG and enabling integrated evaluation of tumor burden and systemic disease activity, with direct implications for clinical decision-making. CLINICALTRIALS: gov NCT06717113. FUNDING: National Natural Science Foundation of China (82472018, 82402320) to Prof. Lei Kang, 82402320 to Dr. Tianyao Wang); Beijing Nova Program (20240484725) to Prof. Lei Kang; National High Level Hospital Clinical Research Funding (Interdisciplinary Research Project of Peking University First Hospital, 2024IR07, Scientific and Technological Achievements Transformation Incubation Guidance Fund Project of Peking University First Hospital, 2025CX38, 2024CX18) to Prof. Lei Kang.