Good news, bad news for GlaxoSmithKline on Monday: A treatment for metastatic lung cancer receives “Breakthrough Therapy” designation from the FDA. However, GSK also says it has dropped development of a muscular dystrophy treatment.

GSK (NYSE: GSK) said the FDA had awarded the “breakthrough” designation for Tafinlar for patients who have received some chemotherapy.

However, the “breakthrough” status does not mean approval.

Based on changes made in 2012 under the FDA Safety and Innovation Act, however, the “breakthrough” status is designed to expedite development and review of drugs that treat serious or life-threatening medical conditions when early evidence “demonstrates that the drug may have substantial improvement on at least one clinically significant endpoint over available therapies,” the drug giant noted in a statement.

Breakthrough Therapy designation includes all the features of the Fast Track designation, as well as more intensive guidance from the FDA on a drug’s clinical development program.

GSK will receive “intensive guidance” from the FDA as well as other benefits provided to companies whose candidates have been declared “Fast Track.”

Tafinlar is already approved for use against melanoma, the deadliest form of skin cancer. 

MD Partnership Dropped 

Meanwhile, GSK ended its four- year partnership with Prosensa Holding NV to develop a Duchenne muscular dystrophy treatment after the therapy failed to help patients walk better in a clinical trial. Prosensa shares fell as much as 23 percent.

Prosensa will regain the rights to the drug, known as drisapersen, and to all other development programs related to the neuromuscular disease, the companies said today in separate statements. The company, based in the Netherlands, has a total of six compounds in development for the illness, including drisapersen and three others in human testing.

Prosensa is still considering a regulatory filing of drisapersen, given the mid-stage study showed promise in treating patients in the early stage of disease, Chief Executive Officer Hans Schikan said in a telephone interview. Longer treatment may also benefit patients, he said.

“When you start the treatment and how long you treat are the key questions,” Schikan said. Full analysis of the trials has not yet been completed, he said.

 Glaxo and Prosensa said they plan to make certain details of the drisapersen studies available to scientists to advance understanding of the disease, which affects about one in 3,500 newborn boys and has no known cure. The companies also plan to publish study results in a peer-reviewed journal.

GSK operates its North American headquarters in RTP.

[GSK ARCHIVE: Check out more than a decade of GSK stories as reported in WRALTechWire.]