Boehringer Ingelheim will return development and global commercialization rights to Hanmi Pharmaceutical’s lung cancer candidate olmutinib, the companies said today, ending a year-long collaboration that could have generated up to $730 million for the South Korean drug developer.

Olmutinib—also known as HM61713 and BI 1482694—is a third-generation epidermal growth factor receptor (EGFR)-targeted therapy for EGFR mutation-positive lung cancer. Olmutinib is approved as a treatment for EGFR T790M mutation-positive lung cancer in South Korea.

Boehringer Ingelheim said it opted to end development of olmutinib—also known as HM61713 and BI 1482694—following “a re-evaluation of all available clinical data on olmutinib and recent treatment advances.”

Those advances include positive Phase III results for three other EGFR-targeting treatment candidates for non-small-cell lung cancer (NSCLC)—Tagrisso, developed by AstraZeneca; Tecentriq™ (atezolizumab), a programmed death-ligand 1 (PD-L1) inhibitor developed by Genentech, a member of the Roche Group; and Merck & Co.’s Keytruda (pembrolizumab), which in June showed superiority over chemotherapy in the KEYNOTE-024 trial for both the primary endpoint of progression-free survival and the secondary endpoint of overall survival.

However, Boehringer Ingelheim’s decision comes the same day that South Korea’s Ministry of Food and Drug Safety issued a safety letter following two cases of toxic epidermal necrolysis, one of them fatal, and one case of Stevens-Johnson-Syndrome (non-fatal) during a Phase II trial of olmutinib.

Olmutinib’s dosage was reduced to reduce the toxicity, but the drug’s efficacy declined as a result, leading to the termination of the trial, an oncology professor told a Korean news organization, according to The Korea Herald, which did not name the professor or the organization.

“We previously informed regulatory authorities, including the FDA, about relevant safety data related to olmutinib, including side effects such as severe skin reactions,” Boehringer Ingelheim said in a statement to GEN. “For studies for which Boehringer Ingelheim is responsible all investigators received timely communications regarding these findings and were instructed to inform their patients accordingly.”

Hanmi shares fell 18% in trading on the Korea Exchange, falling to their lowest level since October 2015.

Hanmi said in a regulatory filing that it would not have to return $65 million in upfront and milestone payments it received from Boehringer Ingelheim.

Under the collaboration, announced July 28, 2015, Boehringer Ingelheim agreed to pay Hanmi $50 million upfront, up to $680 million in milestone payments, plus tiered double-digit royalties on future net sales. At the time, the companies said, they aimed to aim to achieve market authorization for HM61713 for patients with EGFR mutation-positive NSCLC by 2017 in the U.S.

In its statement today, Boehringer Ingelheim insisted that it remained committed to growing its oncology offerings, saying that a third of its human drug pipeline set to enter Phase I clinical trials in the next 12 months consists of treatment candidates against cancer.

Boehringer Ingelheim this week announced an up-to-$225 million partnership with ViraTherapeutics to co-develop its oncolytic virus therapy platform and lead candidate vesicular stomatitis virus glycoprotein (VSV-GP), as well as a collaboration with Sarah Cannon Research Institute to study a combination of two of the company’s checkpoint inhibitors—the monoclonal antibodies BI 754091(anti- PD-1) and BI 754111 (anti-LAG-3 [anti-lymphocyte activation gene-3])—in NSCLC and other cancers “with high unmet medical needs.”

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