IVD Technology Magazine
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Originally published September, 1998

IVD Technology News

HAMA assay debuts

Although murine monoclonal antibodies are frequently used in the manufacture of in vitro diagnostics, such uses are not entirely free of difficulties. Interaction with undetected antibodies present in patient samples can cause test results to skew wildly, making the IVD test useless.

But now, a new assay is giving clinicians the tool they've needed to test for such interactions. Developed by Immunomedics, Inc. (Morris Plains, NJ), the assay is the first commercially available test for human antimouse antibodies (HAMA).

Patients who have received murine monoclonal antibodies as part of a diagnostic or therapeutic procedure can develop significant amounts of circulating HAMA. High levels of HAMA can negate the benefits of monoclonal therapeutic agents or cause anomalous results in subsequent in vitro testing. Further, patients can be at risk for allergic reactions or even anaphylaxis.

Hoping to improve patient safety, Immunomedics developed the Immustrip HAMA IgG assay as an adjunct to its research in the field of antibody therapeutics. The Immustrip system is a direct enzyme-linked immunosorbent assay (ELISA) that detects serum levels of antibodies against mouse proteins. It uses a standard 96-microwell format, and delivers semiquantitative results. Assays can be completed in less than an hour and read on a colorimetric plate reader.

Immunomedics reports detecting circulating antibodies down to a concentration of 37 ng/ml. The company recommends monitoring HAMA levels throughout the course of treatment and comparing them to baseline levels.

Rohini Mitra of Immunomedics' production department says that the product "was really developed as an accessory for our diagnostic and therapeutic antibody products." In an unusual regulatory twist, she adds, "FDA approached us about making this assay. We weren't going to market it, but the agency gave us approval."—Gary Woo