PSA Discoverer Says Antigen Test Is Misused, Unreliable

A Harbinger of Prostate Cancer Recurrence

Dr. Topol: Immunotherapy is one of the newest dimensions of cancer. That was your early work where you observed the PSA, but at that point did you think it was specific for cancer?

Dr. Ablin: To my dismay and disappointment, the tissue-specific antigen that I found -- PSA -- was the same protein found in the normal (benign) as well as the malignant prostate. It wasn't what I was looking for. We didn't have monoclonal antibodies in 1970, but with available techniques, we could see a spike in the area where PSA would have occurred, from a molecular standpoint. After treatment, if we followed this level, we saw a reduction of that peak. That was the forerunner of the test approved by the FDA in 1986 -- the PSA test that was the harbinger of the recurrence of the disease.

Dr. Topol: Yourbook reviews 40-plus years of the PSA test and what happened. One of the first things you discuss is how the PSA was commercialized by a San Diego company called Hybritech. This was the first company to manufacture a commercial PSA test. Was that commercialization of the PSA ill-founded?

Dr. Ablin: The difficulty is that the 1986 approval by the FDA was to use the protein as a harbinger of the recurrence of the disease, and that is what it is used for today. This is a very important observation. Because of the tissue specificity of the protein, it allows us to follow a patient after treatment. When you remove the prostate, for example, you remove the source of the protein.

Dr. Topol: That is a legitimate use of the PSA -- to track the prostate gland after surgery. So you didn't have a problem with the commercialization or initial FDA approval?

Dr. Ablin: One problem with the FDA approval was that when Paul Lange presented data to the advisory committee meeting in 1985, Hybritech was really after detection. They had in mind developing some sort of blockbuster drug or form of immunotherapy. There was some disappointment on their part when they went to the FDA, because they didn't have prospective data. They had only retrospective data, and a lot of questions were raised. They didn't get what they wanted to get in 1986.

Cite this: PSA Test Is Misused, Unreliable, Says the Antigen's Discoverer - Medscape - Aug 08, 2014.

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