Whole-Body Dosimetry for Individualized Treatment Planning of ¹³¹I-MIBG Radionuclide Therapy for Neuroblastoma

Abstract

The aims of this study were to examine the relationship between whole-body absorbed dose and hematologic toxicity and to assess the most accurate method of delivering a prescribed whole-body absorbed dose in 131 I-metaiodobenzylguanidine ( 131 I-MIBG) therapy for neuroblastoma. Methods: A total of 20 children (1-12 y), 5 adolescents (13-17 y), and 1 adult (20 y) with stage 3 or 4 neuroblastoma were treated to a prescribed whole-body absorbed dose, which in most cases was 2 Gy. Forty-eight administrations of 131 I-MIBG were given to the 26 patients, ranging in activity from 1,759 to 32,871 MBq. For 30 administrations, sufficient data were available to assess the effect of whole-body absorbed dose on hematologic toxicity. Comparisons were made between the accuracy with which a whole-body absorbed dose could be predicted using a pretherapy tracer study and the patient's most recent previous therapy. The whole-body absorbed dose that would have been delivered if the administered activity was fixed (7,400 MBq) or determined using a weight-based formula (444 MBqÁkg 21 ) was also estimated. Results: The mean whole-body absorbed dose for patients with grade 4 Common Terminology Criteria for Adverse Events (CTCAE) neutropenia after therapy was significantly higher than for those with grade 1 CTCAE neutropenia (1.63 vs. 0.90 Gy; P 5 0.05). There was no correlation between administered activity and hematologic toxicity. Absorbed whole-body doses predicted from previous therapies were within 610% for 70% of the cases. Fixed-activity administrations gave the largest range in whole-body absorbed dose (0.30-3.11 Gy). Conclusion: The results indicate that even in a highly heterogeneous and heavily pretreated patient population, a whole-body absorbed dose can be prescribed accurately and is a more accurate predictor of hematologic toxicity than is administered activity. Therefore, a whole-body absorbed dose can be used to deliver accurate and reproducible 131 I-MIBG therapy on a patient-specific basis.

Dosimetric results in treatments of neuroblastoma and neuroendocrine tumors with 131I‐metaiodobenzylguanidine with implications for the activity to administer

“…Figure 3 shows 285 Eq. (2) in relation to data acquired in this study, and combined with data from Toporski et al 11 and Buckley et al 25 Regarding NET (Table 5) …”

“…Hematologic toxicity is dose limiting in 131 I-mIBG therapy [23][24][25] . When activities above 444…”

A Phase 1, Open-Label Study of the Biodistribution, Pharmacokinetics, and Dosimetry of 223Ra-Dichloride in Patients with Hormone-Refractory Prostate Cancer and Skeletal Metastases

“…Whole-body dosimetry can be calculated accurately and has proven to be a reliable surrogate for the absorbed dose delivered to the red marrow in studies of 131 I-metaiodobenzylguanidine therapy (29). The relative simplicity of this procedure also facilitates its routine clinical use.…”

Biologically effective dose in fractionated molecular radiotherapy—application to treatment of neuroblastoma with131I-mIBG

“…For patients exceeding 33 kg, the prescription 444 MBq/kg can thus not be followed at the Gurutzeta-Cruces University Hospital. Although patients treated for NB usually have lower masses, in the study by Buckley et al (2009), 5 out of 26 of the included patients (19%) had masses exceeding 33 kg. Thus, in facilities where there is an upper activity limit, additional fractionation may be an option in order to follow the total prescribed activity while still complying with local regulations.…”