GSK plc and Spero Therapeutics, Inc. announced they have entered into an exclusive licence agreement for tebipenem pivoxil hydrobromide (tebipenem HBr), a late-stage antibiotic being developed by Spero, as the first oral carbapenem antibiotic to potentially treat complicated urinary tract infections (cUTI), including pyelonephritis, caused by certain bacteria. Spero will start a new phase III clinical trial in 2023, following encouraging US FDA regulatory feedback on the proposed clinical trial design. Financial terms: GSK will receive an exclusive licence to develop and commercialise tebipenem pivoxil HBr in all countries except Japan and certain other Asian countries that Spero partner Meiji Seika will retain.

Under the licence agreement, Spero will be responsible for the execution and costs of the remaining phase III clinical trial of tebipenem HBr. GSK will be responsible for the execution and costs of additional clinical development, including regulatory submission and commercialisation activities for tebipenem HBr in the countries mentioned above. Under the terms of the licence agreement, GSK will make an upfront initial payment to Spero of $66 million to secure rights to the medicine.

Remaining potential payments are milestone-based. In connection with the licence agreement and under a stock purchase agreement between GSK and Spero, GSK has agreed to make a $9 million investment in Spero common stock, purchasing 7,450,000 shares at a purchase price of approximately $1.20805 per share, not to exceed 19.99% beneficial ownership of Spero by GSK and its affiliates. The transactions are expected to close in the fourth quarter of 2022, subject to customary closing conditions, including the expiration of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended.

The closing of the equity investment is conditioned upon the effectiveness of the licence following Hart-Scott-Rodino clearance.