CHICAGO, May 16 (Reuters) – An experimental Loxo Oncology Inc drug targeting cancer with errors in the RET gene resulted in tumor shrinkage in nearly 70 percent of patients, regardless of where the cancer-derived study came from released on Wednesday.
The drug, LOXO-292, was well tolerated by patients with advanced cancer, many of whom were resistant or no longer supported by available treatments, researchers reported.
Oral medicine is intended for cancer patients with RET anomalies, in which two genes are fused together, triggering accelerated cancer cell growth.
RET fusions, an acquired and non-inherited genetic defect, occur in about 2 percent of lung cancers, 10 to 20 percent of papillary thyroid carcinomas, and a small number of other cancers. Other mutations known as activating RET point mutations account for about 60 percent of medullary thyroid carcinomas, accounting for 3 percent of all thyroid cancers.
As of January 5, data included 35 patients with RET fusion-positive tumors, including 27 with non-small cell lung cancer (NSCLC), 7 with papillary thyroid cancer, and 1
In patients with positive RET fusion, 69 percent of those who could be evaluated had significant tumor shrinkage, based on standard criteria for the overall response, typically a shrinkage of at least one-third.
The overall response rate was 65 percent for patients with NSCLC, including three whose cancer had spread to the brain and 83 percent for patients with papillary thyroid cancer.
In patients with medullary thyroid carcinoma, 79 percent showed a tumor shrinkage of 9 to 45 percent.
A brief summary of the findings was released on Wednesday before the American Society of Clinical Oncology Meeting Chicago next month where more detailed data on the study will be presented with more patients.
Loxo boss Josh Bilenker said in a telephone conversation with analysts earlier this month that he was "encouraged by the data we provided in January," he said, but since January effectiveness has improved.
The findings follow initial results published by Blueprint Medicines at a cancer conference last month, whose rival RET drug had an overall response rate of 37 percent, including 45 percent for NSCLC and 32 percent for medullary thyroid cancer.
Of the 57 patients in the study, 52 remained on treatment. Side effects were usually minor and occurred in about 10 percent of patients. They include fatigue, diarrhea and shortness of breath or breath. (Report by Julie Steenhuysen, edited by Bill Berkrot)