In the experiment described below the researchers failed to show that their special scintigraphycould be used to predict whether or not Herceptin would cause heart problems.(Although they state a blood maker,NT-proBNP, may be a promissing tool).
However it identified cancerous lesions which were HER positive because it used Herceptin attached to a radioactive element(indium) as an injected marker.
One wonders if this selective display of HER tumours could eventually be used in comparison with a regular PET scan (where the injected radioactive marker is a non selective glucose) to detect the sites of tumours that are not HER positive in the entire body except in the brain.(The brain is not penetrated by Herceptin).
This might help to fine tune the treatment regimen to cover more than one type of tumour & make it possible at an early stage since regular PET scans can now detect lesions as small as 2 to 5 mm.
http://www.ncbi.nlm.nih.gov/entrez/q...&dopt=Abstract
Indium-111-labeled trastuzumab scintigraphy in patients with human epidermal growth factor receptor 2-positive metastatic breast cancer.
Perik PJ,
Lub-De Hooge MN,
Gietema JA,
van der Graaf WT,
de Korte MA,
Jonkman S,
Kosterink JG,
van Veldhuisen DJ,
Sleijfer DT,
Jager PL,
de Vries EG.
Department of Medical Oncology, Hospital Pharmacy, Nuclear Medicine and Cardiology, University of Groningen and University Medical Center Groningen, Groningen, The Netherlands.
PURPOSE: The cardiac and antineoplastic effects of trastuzumab may be related to specific uptake of trastuzumab in myocardium and tumor tissue, respectively. We evaluated whether indium-111 (111In)-labeled trastuzumab scintigraphy can predict cardiotoxicity and identify tumor lesions. In addition, we evaluated whether plasma markers for cardiac dysfunction can be used to predict cardiotoxicity.
PATIENTS AND METHODS:
Patients with human epidermal growth factor receptor 2 (HER2) -positive metastatic breast cancer underwent gamma camera imaging from 15 minutes to 7 days after injection of 150 MBq 111In-diethylenetriamine penta-acetic acid anhydride (DTPA) -trastuzumab, after loading-dose trastuzumab, and after once-a-week trastuzumab doses for 11 weeks, and concomitant paclitaxel once every 3 weeks. Cardiac assessments were performed before treatment, and after four and six cycles. Plasma N-terminal probrain natriuretic peptide (NT-proBNP) and serum troponin I were measured with immunoassay.
RESULTS:
Fifteen of the 17 patients were available for cardiac and tumor uptake analysis. On the first scan, myocardial 111In-DTPA-trastuzumab uptake was observed in one patient with pre-existing cardiac arrhythmias, who did not develop heart failure during treatment. Severe cardiotoxicity occurred in three patients, without initial myocardial uptake, whereas one showed weak myocardial uptake after four cycles. The detection rate of single tumor lesions was 45%. New tumor lesions were discovered in 13 of 15 patients. Pretreatment plasma NT-proBNP levels were higher in patients with than without heart failure (mean, 534 [standard deviation, 236] v 105 [standard deviation, 79] ng/L; P = .009).
CONCLUSION:
Radiolabeled trastuzumab scintigraphy was not valuable in predicting trastuzumab-related cardiotoxicity in metastatic breast cancer patients, but can identify HER2-positive tumors. Measurement of plasma NT-proBNP is promising regarding prediction of trastuzumab-related cardiotoxicity.
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