Shares of Acorda Therapeutics Inc. (ACOR) - Get Report were down 24.32%, or $6.25 to $19.45 Tuesday, Aug. 29, after the Ardsley, N.Y.-based firm received a refusal to file (RTF) letter from the U.S. Food and Drug Administration regarding the new drug application Acorda had submitted in June for Inbrija, a potential treatment for Parkinson's disease.

Acorda said the agency had determined that the application was not sufficiently complete for the FDA to do a substantive review. "FDA specified two reasons for the RTF: first, the date when the manufacturing site would be ready for inspection, and, second, a question regarding the submission of the drug master production record," Acorda said.

"FDA also requested additional information at resubmission, which was not part of the basis for the RTF," the company added.

Ron Cohen, MD, Acorda's president and CEO, said in the news release that the company will work with the agency to address the open issues and clarify the path to re-submit the application.

Inbrija is a potential treatment for systems of OFF periods in people with Parkinson's disease taking a carbidopa/levodopa regimen. An OFF period pertains to the re-emergence of symptoms.

For Acorda, the receipt of the RTF letter from the FDA came after investor Scopia Capital Management LP sent a letter to Acorda's board on Aug. 7 urging the firm "to pursue an immediate review" of its strategic options, including a sale of the entire company.

In a statement issued in response to Scopia's letter, Acorda said its board and management "thoroughly considered options to enhance shareholder value" and "unanimously determined" that focusing on Inbrija and tozadenant, two late-stage programs in Parkinson's disease, "is the best path forward to create value for shareholders."

"A sale of the company at the present time would not adequately compensate shareholders for the potential benefits of the company's late-stage programs," Acorda said.

Meanwhile, shares of ImmunoGen Inc. (IMGN) - Get Report jumped 7.1% to $6.92 after the Waltham, Mass.-based firm and Dublin-based Jazz Pharmaceuticals plc (JAZZ) - Get Report unveiled a collaboration and option agreement

Jazz will have exclusive, worldwide rights to opt into development and commercialization of two early-stage, hematology-related antibody-drug conjugate (ADC) programs, plus another program to be designated during the term of the agreement.

ImmunoGen will be responsible for the development of the three ADC programs prior to any potential opt-in by Jazz.

As part of the pact, Jazz will make a $75 million upfront payment to ImmunoGen. Jazz will also pay up to $100 million in development funding over seven years to support the three ADC programs.

Jazz shares were trading at $145.43, down 0.5%.

More of What's Trending on TheStreet: