Iodine-131--metaiodobenzylguanidine double infusion with autologous stem-cell rescue for neuroblastoma: a new approaches to neuroblastoma therapy phase I study.
OBJECTIVE
Iodine-131-metaiodobenzylguanidine ((131)I-MIBG) provides targeted radiotherapy with more than 30% response rate in refractory neuroblastoma, but activity infused is limited by radiation safety and hematologic toxicity. The goal was to determine the maximum-tolerated dose of (131)I-MIBG in two consecutive infusions at a 2-week interval, supported by autologous stem-cell rescue (ASCR) 2 weeks after the second dose.


METHODS
The (131)I-MIBG dose was escalated using a 3 + 3 phase I trial design, with levels calculated by cumulative red marrow radiation index (RMI) from both infusions. Using dosimetry, the second infusion was adjusted to achieve the target RMI, except at level 4, where the second infusion was capped at 21 mCi/kg.


RESULTS
Twenty-one patients were enrolled onto the study at levels 1 to 4, with 18 patients assessable for toxicity and 20 patients assessable for response. Cumulative (131)I-MIBG given to achieve the target RMI ranged from 22 to 50 mCi/kg, with cumulative RMI of 3.2 to 8.92 Gy. No patient had a dose-limiting toxicity. Reversible grade 3 nonhematologic toxicity occurred in six patients at level 4, establishing the recommended cumulative dose as 36 mCi/kg. The median time to absolute neutrophil count more than 500/microL after ASCR was 13 days (4 to 27 days) and to platelet independence was 17 days (6 to 47 days). Responses included two partial responses, eight mixed responses, three stable disease, and seven progressive disease. Responses by semiquantitative MIBG score occurred in eight patients, soft tissue responses occurred in five of 11 patients, but bone marrow responses occurred in only two of 13 patients.


CONCLUSIONS
The lack of toxicity with this approach allowed dramatic dose intensification of (131)I-MIBG, with minimal toxicity and promising activity.
Matthay
Katherine K
KK
Department of Pediatrics, University of California, San Francisco, 505 Parnassus, M647, San Francisco, CA 94143-0106, USA. matthayk@peds.ucsf.edu
Quach
Alekist
A
Huberty
John
J
Franc
Benjamin L
BL
Hawkins
Randall A
RA
Jackson
Hollie
H
Groshen
Susan
S
Shusterman
Suzanne
S
Yanik
Gregory
G
Veatch
Janet
J
Brophy
Patricia
P
Villablanca
Judith G
JG
Maris
John M
JM
D019797:3-Iodobenzylguanidine / Q000008:administration & dosage* / Q000009:adverse effects; D000970:Antineoplastic Agents / Q000008:administration & dosage* / Q000009:adverse effects; D001853:Bone Marrow / Q000187:drug effects; D002648:Child; D002675:Child, Preschool; D003131:Combined Modality Therapy; D064420:Drug-Related Side Effects and Adverse Reactions; D005260:Female; D006801:Humans; D007223:Infant; D007262:Infusions, Intravenous; D008297:Male; D020714:Maximum Tolerated Dose; D009447:Neuroblastoma / Q000188:drug therapy* / Q000532:radiotherapy; D033581:Stem Cell Transplantation; D016019:Survival Analysis
D000970:Antineoplastic Agents; D019797:3-Iodobenzylguanidine