Myelosuppression in patients treated with ¹⁷⁷Lutetium-lilotomab satetraxetan can be predicted with absorbed dose to the red marrow as the only variable

Abstract

Background

The aim of this study was to investigate dosimetry data and clinical variables to predict hematological toxicity in non-Hodgkin lymphoma (NHL) patients treated with [¹⁷⁷Lutetium]Lu-lilotomab satetraxetan.

Material and methods

A total of 17 patients treated with [¹⁷⁷Lu]Lu-lilotomab satetraxetan in a first-in-human phase 1/2a study were included. Absorbed dose to the red marrow was explored using SPECT/CT-imaging of the lumbar vertebrae L2–L4 over multiple time points. Percentage reduction of thrombocytes and neutrophils at nadir compared to baseline (PBN) and time to nadir (TTN) were chosen as indicators of myelosuppression and included as dependent variables. Two models were applied in the analysis, a multivariate linear model and a sigmoidal description of toxicity as a function of absorbed dose. A total of 10 independent patient variables were investigated in the multivariate analysis.

Results

Absorbed dose to the red marrow ranged from 1 to 4 Gy. Absorbed dose to the red marrow was found to be the only significant variable for PBN for both thrombocytes and neutrophils. The sigmoid function gave similar results in terms of accuracy when compared to the linear model.

Conclusion

Myelosuppression in the form of thrombocytopenia and neutropenia in patients treated with [¹⁷⁷Lu]Lu-lilotomab satetraxetan can be predicted from the SPECT/CT-derived absorbed dose estimate to the red marrow.

Keywords:

• Non-Hodgkin lymphoma
• internal dosimetry
• radioimmunotherapy
• myelosuppression

Acknowledgments

We thank the personnel at the Nuclear Medicine section at Oslo University Hospital for technical assistance with the acquisitions.

Disclosure statement

Arne Kolstad is a member of the Scientific Advisory Board of Nordic Nanovector ASA. Jostein Dahle is an employee and shareholder of Nordic Nanovector ASA. The authors have no further conflicts of interest to disclose.

Additional information

Funding

The present work was financially supported by the South-Eastern Norway Regional Health Authority.