Blueprint Medicines Corp. said its selective oral inhibitor drug BLU-667, which targets oncogenic RET fusions and mutations, showed cancer reduction in a phase 1 clinical trial in patients with RET-altered cancers.

Results from the ARROW study showed a reduction in cancer in patients with RET-fusion non-small cell lung cancer, or NSCLC, and RET-mutant medullary thyroid cancer. Both patient groups included patients who had received prior treatment. Cancer was reduced in certain patients with papillary thyroid cancer as well.

Blueprint intends to submit two new drug applications to the U.S. Food and Drug Administration in the first half of 2020 for BLU-667 based on the new trial results, according to a June 3 press release. The company will submit separate new drug applications for treating both RET-fusion NSCLC and RET-mutant medullary thyroid cancer.

RET is a gene that provides instructions for producing RET proteins, which communicate within cells, such as by signaling instructions to divide or take on special functions, according to the U.S. National Library of Medicine. RET mutations have been identified in several types of cancer, including lung cancer.

About 1 in 75 NSCLCs have a mutation in the RET gene that alters RET proteins. The most common change is called a RET fusion, according to Vanderbilt University Medical Center's website My Cancer Genome.

The ARROW study showed cancer reduction in 60% of patients with RET-fusion NSCLC, and 90% of NSCLC patients showed radiographic tumor reductions. Of the 48 patients studied with RET-fusion NSCLC, 35 were previously treated with chemotherapy.

After being treated with BLU-667, the disease stopped spreading in 100% of patients who already received chemotherapy treatment

The data also showed reductions in 63% of patients with RET-mutant medullary thyroid cancer. Sixteen of the 32 patients studied with the cancer type received previous treatment from chemotherapy or cabozantinib, which is used in Exelixis Inc.'s Cabometyx and Cometriq.

After treatment, the disease did not spread in 94% of patients who already received treatment from chemotherapy or cabozantinib.

The majority of side effects were reported as grade 1 or 2, including reports of constipation, hypertension and anemia, according to the press release. Grade 3 or 4 adverse events were reported about 2% of the time and included hypertension, anemia and a low count of white blood cells.

The 2019 American Society of Clinical Oncology meeting is expected to bring together more than 32,000 professionals from around the world, with more than 2,400 study abstracts to be presented on-site and an additional 3,200 abstracts to be published online.