RECAF

RECAF is a receptor for AFP (Alpha-fetoprotein). AFP is a marker for liver and testicular cancer that was discovered by Dr. Garri Abelev, a member of our Scientific Advisory Board. RECAF should not be confused with AFP; they are two different molecules.

RECAF is normally expressed by developing cells during fetal and embryonic life, but not expressed in most adult normal cells which makes this marker an oncofetal antigen (AFP and CEA, two commonly used cancer markers, are also oncofetal antigens).

RECAF is found on most cancer cells, including breast, colon, prostate and lung cancers, but not on most normal or benign tumor cells. The figure below shows tissue sections stained with a special technique that makes RECAF appear brown:

	(1) Ductal carcinoma. (2) Ductal carcinoma. RECAF positive malignant cells to the right of a negative, non-malignant duct. (3) Benign fibroadenoma (negative with some brown background staining in the peripheral collagen). (4) Ductal benign hyperplasia (negative).

RECAF based blood test for cancer:

RECAF can be used in blood tests to determine if a patient has cancer.  The blood test can be formatted for use in large clinical and hospital laboratories on automated instrumentation, such as our licensee's Abbott's Architect® or it can be run manually. It can also be formatted as a single use rapid test for point-of-care (POC) use in physicians’ offices, urgent care facilities and at the bedside.  Once approved by the U.S. Food and Drug Administration (FDA), the tests could find application in general screening, in high risk patients to determine if an individual has cancer, as an aid in the diagnostic process of a patient with clinical symptoms of cancer or to follow up patients who are in remission after treatment.

Unlike other cancer markers, such as CEA and PSA, which only detect the presence of a specific cancer type (e.g., CEA for colon cancer and PSA for prostate cancer), RECAF is found on most types of cancer and therefore it may be applicable to a much larger patient population. This is particularly important for follow up of treated patients because their type of cancer is already known; what is needed is a simple and inexpensive way to detect if it is coming back, usually in the form of metastases.

Based on our own results and those obtained by Abbott Diagnostics, which were jointly presented at an international cancer conference, RECAF appears to be a cancer marker with clinical potential for detecting multiple types of cancer.

The table below depicts the sensitivity (the percentage of cancer cases that tested positive with the RECAF test) and the specificity (the percentage of non-cancer cases that tested negative with the test) of the test for different types of cancer compared to healthy patients:

The picture below shows the same concept in a graphic form and in addition, shows that the majority of prostate and breast benign lesions in this study were negative. Each point represents one case. The horizontal lines represent the value (cutoff) under which 95% (light blue) or 99% (blue) of the normal samples fall.

This is important because there are two frequently found situations which are difficult to resolve with current diagnostic methods: One is to differentiate prostate cancer from benign tumors (properly called Benign Prostate Hyperplasia or BPH) using the PSA marker. The other is to differentiate breast cancer from benign tumors of the breast (fibromas) using mammography.

Prostate cancer and BPH:

The table and the ROC curve below show the results from an experiment using blinded samples provided by an external research group. Each sample was tested with PSA (by the extramural scientists) and with RECAF in our facilities. Once we reported the results, the extramural scientists provided us with the code matching the samples with the medical condition (prostate cancer or BPH).

To learn more about ROC curves click here. As a rule of thumb, the straighter the angle on the left top corner, the better the assay works and the more shallow the curve (following the gray line below) the worse the performance of the assay.