Subsequent Events

6 Months Ended

Jun. 30, 2019

Subsequent Events [Abstract]

Subsequent Events

13. Subsequent Events

On July 12, 2019, the Company completed the sale to 14ner (the “14ner Sale”) of its anti-HER3 antibody programs, MM-121 (seribantumab) and MM-111. In connection with the 14ner Sale, the Company received an upfront cash payment of $3.5 million and is eligible to receive up to $54.5 million in additional potential development, regulatory approval and commercial-based milestone payments, consisting of:

• $3.0 million for achievement of the primary endpoint in the first registrational clinical study of either MM-121 or MM-111;

• Up to $16.5 million in total payments for the achievement of various regulatory approval and reimbursement-based milestones in the United States, Europe and Japan; and

• Up to $35.0 million in total payments for achieving various cumulative worldwide net sales targets between $100.0 million and $300.0 million for MM-121 and MM-111.