Pradip K. Maiti

Noninvasive localization of tumors by immunofluorescence imaging using a single chain Fv fragment of a human monoclonal antibody with broad cancer specificity

A single chain antibody fragment, NovoMAb‐G2‐scFv, derived from a human anti‐tumor monoclonal antibody recognizes tumor antigen molecules expressed on a wide variety of human cancers including melanoma, breast carcinoma, colon adenocarcinoma, squamous cell carcinoma, lung carcinoma, and prostate carcinoma. This study was designed to evaluate the use of a NovoMab‐G2‐scFv/cyanine fluorochrome (Cy5.5.18) conjugate as diagnostic tool for in vivo imaging of tumors.

Immunofluorescence imaging as a tool for studying the pharmacokinetics of a human monoclonal single chain fragment antibody

We have used immunofluorescence imaging to study binding of a monoclonal antibody fragment to subcutaneously implanted human melanoma cells in nude mice. The data acquired using this nontraditional approach was then analyzed using standard pharmacokinetic methods to produce estimates of k/sub e/ (0.06 h/sup -1/), t/sub 1/2/ (16 h), mean residency time (23.4 h) and percent exposure of the antibody to the tumor (40%). To our knowledge this is the first time standard pharmacokinetic analyzes have been conducted on immunofluorescence imaging data. The combination of this novel imaging technique and standard pharmacokinetic analytical methods should prove to be a useful tool for comparing the properties of antibody fragments in animal models.

Immunoreactivity of human MAb BT32/A6 with neuroepithelial tumors

The present study was undertaken to determine thepattern of immunoreactivity of BT32/A6, a human IgMmonoclonal antibody (MAb), with the following histological panels:1) 30 human and non-human cell lines, 2)32 normal human tissues, and 3) 28 tumorsof central neuroepithelial origin (16 astrocytic; 11 non-astro-cytic).Antibody BT32/A6 recognizes a surface and cytoplasmic antigenpresent on a variety of human tumor celllines including gliomas, melanomas, neuroblastomas, and a fewsarcomas. The antigen is present (at least focally)on 15/16 astrocytic tumor tissue sections (94%), andin some cases, on close to 100% ofcells. All malignant cell types, including small anaplasticcells, giant cells, gemistocytic cells, and cells formingpseudopalisades were labeled by MAb BT32/A6. Non-astrocytic neuroepithelialtumors did not stain appreciably with MAb BT32/A6.There was weak immunoreactivity in a small subsetof normal human tissues of epithelial and lymphoidorigin, with the exception of adrenal cortex, whichexhibited weak to moderate staining. All normal tissuesof neuroectodermal and mesenchymal origin were unreactive. Inconclusion, MAb BT32/A6 appears to be unique inthat it recognizes a highly-expressed astrocytic tumor-associated antigenthat is present on both low and highgrade tumors. This makes it a strong candidatefor further studies aimed at establishing its usefulnessin the treatment of human astrocytic tumors.