The licensing agreement provides GSK the commercial rights to the antibiotic, tebipenem pivoxil hydrobromide (tebipenem HBr), in all regions except for Japan and certain other Asian countries.
GSK will pay $66m (€68m) upfront for those rights, which could potentially go higher if future milestones are met. Additionally, the company will also purchase $9m in Spero common stock.
Somewhat unusually in such arrangements, GSK choose to outline exactly what milestones would need to be met and what payments would be due as a result. The release specifies that delivery of the Phase III program will result in milestone payments up to $150m, with the first sale of the product in the US or Europe also resulting a $150m milestone payment.
Beyond this, Spero is eligible for up to $225m in net sales-based payments, should the antibiotic go onto achieve sales in excess of $1bn.
According to Luke Miels, CCO at GSK, the company sees potential in the antibiotic due to the need for an alternative to intravenous hospital therapy for drug-resistant complicated urinary tract infections.
The product would also slot into the company’s infectious disease portfolio and strategy, should it be approved.
GSK also has plenty of experience advancing its own antibiotics, with the company developing its own late-stage antibiotic. The company is also a member of Antimicrobial Resistance Benchmark of the Access to Medicine Foundation and participates in the AMR Action Fund, with the latter aiming to bring two to four new antibiotics to patients by 2030.
On the hopes for approval, Miels noted that the antibiotic “has a clear US FDA regulatory path to potential approval.”
Funds to pursue new trial
The deal arrives not long after Spero Therapeutics received a complete response letter (CRL) from the US Food and Drug Administration (FDA) for the antibiotic, in June of this year.
At the time, Spero stated that the FDA had concluded that its Phase III study of the antibiotic was not sufficient to support approval and requested that an additional study be completed. The company’s share price has subsequently suffered, falling approximately 86% year-to-date.
With the backing of GSK, Spero expects to start a new Phase III clinical trial in 2023, after apparently receiving ‘encouraging regulatory feedback’ from the FDA on the proposed clinical trial design.
GSK stated that the transaction is expected to close in the fourth quarter of 2022.