NEW YORK (TheStreet) -- Shares of ImmunoGen  (IMGN) - Get Report  plummeted more than 50% to a 52-week low of $5.36 on Friday after poor results of its experimental breast cancer treatment.

ImmunoGen's drug development partner Roche  (RHHBY)  reported that the drug Kadcyla, which uses ImmunoGen technology, did not show significant improvement in a crucial late-stage study measurement in breast cancer patients.

Roche tested the drug in patients who had yet to receive treatment for the cancer but announced Friday that patients who took Kadcyla did not show a significantly better progression-free survival period than those who received a different treatment.

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Kadcyla has already been approved to treat patients with a form of breast cancer that has spread and who have already tried another treatment.

Kadcyla blends Roche's Herceptin, a chemotherapy drug, and a third chemical developed by ImmunoGen that holds the medicines together. This chemical links the drugs together until they attach to a cancer cell and deliver a strong dose to combat the tumor.

ImmunoGen receives royalties from Roche on sales of Kadcyla.

ImmunoGen CEO Daniel Junius said in a statement that the company is disappointed in the results, but noted Roche has several other Kadcyla trials ongoing, including one for gastric cancer.

ImmunoGen also said the results would not affect 2015 guidance or the approved use of Kadcyla.

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