Canada at the forefront on this one: new radionucleide 2 test 4 minimal residual her2

[Lani]

postive breast cancer and guide surgeons to obtain clear margins when excision her2+ lesions:

Approved in Canada--don't know who using it or when available generally or in trials

Nucl Med Biol. 2011 Jan;38(1):129-36. Epub 2010 Sep 1.
A kit to prepare (111)In-DTPA-trastuzumab (Herceptin) Fab fragments injection under GMP conditions for imaging or radioimmunoguided surgery of HER2-positive breast cancer.
Scollard DA, Chan C, Holloway CM, Reilly RM.

Department of Pharmaceutical Sciences, University of Toronto, Toronto, ON, Canada M5S 3M2.
Abstract
INTRODUCTION: The human epidermal growth factor receptor-2 (HER2) gene is amplified in 25% of invasive breast cancers, and receptor overexpression has been noted in up to 60% of early stages of the disease [ductal carcinoma in situ (DCIS)]. Preclinical studies have revealed high tumor/blood ratios (>27:1) for (111)In-labeled Fab fragments of the HER2 monoclonal antibody, trastuzumab (Herceptin) ((111)In-DTPA-trastuzumab Fab) at 72 h pi in athymic mice bearing subcutaneous human breast cancer xenografts. Our aim in this study was to formulate a kit for preparation of (111)In-DTPA-trastuzumab Fab injection under good manufacturing practice (GMP) conditions suitable for human administration in a Phase I clinical trial of imaging and radioimmunoguided surgery (RIGS) of HER2-positive breast cancer.

METHODS: Fab fragments were produced by digestion of trastuzumab IgG (Herceptin) with immobilized papain for 20 h at 37°C. Fab fragments were purified by ultrafiltration, then reacted with a 10-fold molar excess of diethylenetriaminepentaacetic acid (DTPA) dianhydride. DTPA-Fab fragments were purified, then sterilized by filtration into unit dose glass vials (kits). Kits were tested against specifications for volume (0.9-1.1 ml), protein concentration (0.45-0.55 mg/ml), pH (5.5-6.5), DTPA substitution (0.5-4.0 mol DTPA/mol Fab), appearance (clear, colorless and particle free), labeling efficiency (≥85%), and sterility and apyrogenicity (USP XXXII). Immunoreactivity of (111)In-DTPA-trastuzumab Fab towards HER2 was measured by saturation radioligand binding assays using SKBR-3 human breast cancer cells (specifications: K(a)=0.6-9.6×10(7) L/mol; B(max)=0.6-10.4×10(6) sites/cell). (111)In-DTPA-trastuzumab Fab injection was prepared by adding 80-100 MBq of (111)InCl(3) to a single kit vial and incubating for 30 min at room temperature. (111)In-DTPA-trastuzumab Fab was assayed for the amount of radioactivity and tested for pH, radiochemical purity (RCP), appearance and sterility.

RESULTS: Pure and homogeneous Fab fragments were produced. Eleven lots of kits met established quality specifications. The labeling efficiency with (111)In was 90.6±2.2%. (111)In-DTPA-trastuzumab Fab bound specifically to HER2 on SKBR-3 cells (K(a)=4.8±2.5×10(7) L/mol and B(max)=1.6±0.8×10(6) sites/cell). Thirteen lots of (111)In-DTPA-trastuzumab injection met all established specifications. Kits were stable for 90 days and (111)In-DTPA-trastuzumab Fab injection was stable for 24 h stored at 4°C.

CONCLUSIONS: A kit was formulated under GMP conditions for the preparation of (111)In-DTPA-trastuzumab Fab injection suitable for human administration. The kits were approved by Health Canada.

Copyright © 2011 Elsevier Inc. All rights reserved.
PMID: 21220136 [