Related Experiment Video
Updated: Apr 20, 2026
Murine Model of Leukemia Relapse to Induction Chemotherapy for Acute Lymphoblastic Leukemia
Published on: October 17, 2025
Prospective international cohort study demonstrates inability of interim PET to predict treatment failure in diffuse
Robert Carr1, Stefano Fanti2, Diana Paez3
1Department of Haematology, Guy's and St. Thomas' Hospital, King's College, London, United Kingdom robtcarr@gmail.com.
Unlabelled:
The International Atomic Energy Agency sponsored a large, multinational, prospective study to further define PET for risk stratification of diffuse large B-cell lymphoma and to test the hypothesis that international biological diversity or diversity of healthcare systems may influence the kinetics of treatment response as assessed by interim PET (I-PET).
Methods:
Cancer centers in Brazil, Chile, Hungary, India, Italy, the Philippines, South Korea, and Thailand followed a common protocol based on treatment with R-CHOP (cyclophosphamide, hydroxyadriamycin, vincristine, prednisolone with rituximab), with I-PET after 2-3 cycles of chemotherapy and at the end of chemotherapy scored visually.
Results:
Two-year survivals for all 327 patients (median follow-up, 35 mo) were 79% (95% confidence interval [CI], 74%-83%) for event-free survival (EFS) and 86% (95% CI, 81%-89%) for overall survival (OS). Two hundred ten patients (64%) were I-PET-negative, and 117 (36%) were I-PET-positive. Two-year EFS was 90% (95% CI, 85%-93%) for I-PET-negative and 58% (95% CI, 48%-66%) for I-PET-positive, with a hazard ratio of 5.31 (95% CI, 3.29-8.56). Two-year OS was 93% (95% CI, 88%-96%) for I-PET-negative and 72% (95% CI, 63%-80%) for I-PET-positive, with a hazard ratio of 3.86 (95% CI, 2.12-7.03). On sequential monitoring, 192 of 312 (62%) patients had complete response at both I-PET and end-of-chemotherapy PET, with an EFS of 97% (95% CI, 92%-98%); 110 of these with favorable clinical indicators had an EFS of 98% (95% CI, 92%-100%). In contrast, the 107 I-PET-positive cases segregated into 2 groups: 58 (54%) achieved PET-negative complete remission at the end of chemotherapy (EFS, 86%; 95% CI, 73%-93%); 46% remained PET-positive (EFS, 35%; 95% CI, 22%-48%). Heterogeneity analysis found no significant difference between countries for outcomes stratified by I-PET.
Conclusion:
This large international cohort delivers 3 novel findings: treatment response assessed by I-PET is comparable across disparate healthcare systems, secondly a negative I-PET findings together with good clinical status identifies a group with an EFS of 98%, and thirdly a single I-PET scan does not differentiate chemoresistant lymphoma from complete response and cannot be used to guide risk-adapted therapy.