Early assessment of treatment response in AML using FLT PET/cT: a trial of the ECOG-ACRIN Cancer Research Group (EAI141)

EAI141 was a prospective, multi-center trial designed to assess 3′-deoxy-3′-¹⁸F-fluorothymidine (FLT) PET/CT as a treatment response biomarker. The primary objective was to evaluate the negative predictive value (NPV) of post-treatment ‘day 14’ FLT-uptake (clinically non-responding patients with high FLT uptake). Among 87 patients enrolled from 9 centers, 61 were evaluable for the primary endpoint. The NPV for FLT PET/CT was 0.20 (3/15, 95% CI 0.04–0.48) compared to the NPV for nadir bone marrow of 0.25 (4/16, 95% CI 0.07–0.52). This first multi-center molecular imaging study in patients with AML demonstrated the feasibility of FLT PET/CT imaging. While molecular imaging did not predict response status more accurately than the nadir marrow, this study showed limitations in the accuracy of the ‘day 14’ marrow as a predictor of response and suggested added benefit by combining a marrow assessment and molecular imaging at an earlier time point.