Spero Therapeutics, Inc. announced the closing of its previously announced exclusive license agreement with GlaxoSmithKline Intellectual Property (No. 3) Limited (LSE/NYSE: GSK) (GSK) for tebipenem HBr, an investigational drug being developed as the potentially first oral carbapenem antibiotic for the treatment of complicated urinary tract infections (cUTI), including pyelonephritis, caused by certain bacteria. Pursuant to the license agreement, Spero will be receiving a $66 million upfront payment from GSK and is eligible to receive up to $525 million in development, sales, and commercial milestones payments, as well as low-single digit to low-double digit tiered royalties on net product sales.

In exchange, GSK has been granted an exclusive license to develop and commercialize tebipenem pivoxil and tebipenem pivoxil HBr in all territories, except Japan, and certain other Asian countries, territories which will be retained by Spero partner, Meiji Seika. In connection with closing, pursuant to the license agreement and a previously announced stock purchase agreement between the parties, an affiliate of GSK has purchased 7,450,000 shares of Spero's common stock at a purchase price of $1.20805 per share, resulting in gross proceeds to Spero of approximately $9 million. Under the terms of the license agreement, Spero is responsible for the execution and costs of a follow-up Phase 3 clinical trial of tebipenem HBr.

GSK is responsible for the execution and costs of additional development, including Phase 3 regulatory filing and commercialization activities for tebipenem HBr outside of the Meiji Seika territory.