Biomarker may identify lung cancer during early asymptomatic stage

September 19, 2007

NEW YORK (Reuters Health) - An enzyme that is elevated in malignant tumors may represent a serum biomarker for the early detection of lung cancer, according to a presentation at the International Conference on Molecular Diagnostics in Cancer Therapeutic Development, held this week in Atlanta, Georgia.

Scientists at Panacea Pharmaceuticals, Inc., in Gaithersburg, Maryland, previously used immunohistochemical staining to visualize the protein in question -- human aspartyl (asparaginyl) beta-hydroxylase (HAAH) -- and showed that it is present on the cell surface in > 99% of tumor specimens.

"HAAH is present in the early stages of cellular differentiation," presenter Mark Semenuk explained, "It guides primitive cells to develop into specialized tissue."

"In cancer, HAAH is aberrantly expressed on the cell surface, where it modifies signaling proteins that typically are active only during early cell differentiation," he continued.

As it is exposed on the cell surface of malignant tissue, the investigators theorized that it would also be shed into the blood.

Semenuk and his associates designed a double monoclonal sandwich ELISA for detecting and quantifying HAAH in serum, which was observed in blood of lung cancer patients, reinforcing its potential as a serum biomarker.

They evaluated the methodology in 160 patients with lung cancer, 93 unaffected individuals and 50 smokers not known to have cancer. Serum levels HAAH were increased in 99% of patients with lung cancer but were undetectable in non-cancer subjects.

Furthermore, HAAH was detectable at all stage of lung cancer, the data show, with average serum HAAH levels of 18, 16, 22, and 22 ng/mL for stages I-IV.

Semenuk and his associates expect that, in addition to its potential as a biomarker, HAAH may also represent a potential therapeutic target.