Castle Biosciences has announced that study results of a proprietary predictive test for esophageal cancer demonstrated strong accuracy and specificity in identifying patients who are likely to have tumors that are extremely resistant to standard pre-surgical treatment of chemotherapy and radiation. Data from this second validation study were presented in San Francisco at the 2014 Gastrointestinal Cancers Symposium sponsored by the American Society of Clinical Oncology.
Medical literature shows that approximately 25% of esophageal cancer patients exhibit extreme resistance to standard regimens of chemotherapy and radiation therapy, and therefore do not respond to the pre-surgical treatment. These patients may avoid the toxicities associated with the treatments and instead can be considered for alternative neoadjuvant therapies or move directly to surgery to remove the tumor.
The test, a three-protein biomarker assay, was discovered by researchers at M.D. Anderson Cancer Center (MDACC). Pre-treatment tumor biopsies are used to evaluate treatment resistance with this predictive assay. Studies show it reliably differentiates patients who are complete or partial responders to chemotherapy and radiation from those who are non-responders. The initial, single center validation study of 167 patients demonstrated an accuracy of 92% and specificity of 97%.
In this second, independent, multi-center study presented today, accuracy was 79% and specificity was 95% for classifying which patients are likely to be highly resistant to pre-surgical chemotherapy treatment for esophageal cancer.
"Locally advanced esophageal cancer can be difficult to treat particularly in patients with comorbid illnesses or advanced age," commented Kenneth Kesler MD, Professor of Surgery, Thoracic Oncology Program, Indiana University. "Induction chemotherapy and radiation therapy are recommended prior to surgery in most cases. However, induction therapy can result in significant toxicity and will achieve no clinical benefits in up to a quarter of patients. The ability to identify resistance to certain chemotherapy agents allows selection of alternative chemotherapy agents or treatment strategies."
The predictive algorithm classifies patients as either exCTRT (extreme resistance to chemo-radiation; College of American Pathology Treatment Response Grade 3) or non-exCTRT (non-extreme resistance to chemo-radiation; College of American Pathology Treatment Response Grade 0, 1, or 2). The test, DecisonDx-EC, uses compartmental localization of the biomarkers NF-kB, Gli1 and SHH in pre-treated tumor biopsies to determine a localization index score for each biomarker. This information is then analyzed using a proprietary algorithm to predict exCTRT or non-exCTRT. The test is currently available for physicians to order through Castle Biosciences. More information can be found at www.myesophagealcancer.com.