Spero: FDA notified the suspension of its phase IIa clinical trial of SPR720 to treat NTM-PD

Spero Therapeutics (SPRO) has announced that the U.S. Food and Drug Administration (FDA) has notified the suspension of its SPR720 Phase IIA clinical trial.

SPR720 is a new type of antibacterial agent that targets enzymes necessary for bacterial DNA replication. SPR720 comes from Vertex and is currently being developed by Spero as an oral therapy for the treatment of non-tuberculous mycobacterial (NTM) disease, a rare orphan disease.  NTM is a pervasive environmental pathogen that causes progressive lung injury and respiratory failure, especially in patients with compromised immune systems or underlying lung disease.Although rare, the incidence of pulmonary NTM disease is on the rise worldwide. The treatment of pulmonary NTM disease requires extended treatment time (lasting approximately 12-24 months), combined use of most unapproved drugs, and is often complicated by tolerability and/or toxicity issues.  In addition, there are currently no approved oral antibiotics specifically for the treatment of lung NTM disease.So, if approved, SPR720 would be the first oral antibiotic approved for the treatment of this disease.

Spero received oral notification of the phase IIa clinical trial for SPR720 but has not yet received written notification from the FDA.Prior to the clinical suspension, Spero notified the FDA of its decision to suspend administration of SPR720 in its Phase IIA clinical trial as a precautionary measure in its ongoing animal toxicology study of SPR720.

The decision to implement the suspension was made based on the recommendations of the Spero Safety Review Board (SRB), which reviewed the data of the ongoing SPR720 toxicology study on adult non-human primates. In the study, it was observed that there was no treatment difference. Determine the mortality of causality.  Animal studies are currently being conducted to assess the potential toxicity of SPR720 over a 4-month period.A simultaneous 4-month study of SPR720 in rats has gone well.These studies were designed to support the long-term treatment of SPR720.SPERO is in the process of discussing the results of the evaluation with the FDA and identifying ways to further develop the SPR720 clinical program.No serious adverse events were observed in any human study participants.

Spero launched a phase IIa clinical trial (SPR720-201) in December 2020.This multi-center, partially blind, placebo-controlled, proof-of-concept trial of SPR720 was designed to enroll approximately 90 patients with NTM-PD caused by Mycobacterium avium complex (MAC).Patients enrolled in the trial were randomized to receive SPR720 500mg or 1,000 mg orally, once daily, placebo or standard therapy (SoC), including macrolide and ethambutol, plus the option to add rifamycin.

The safety and tolerability of oral SPR720 was evaluated in a phase I clinical trial (SPR720-101) completed in December 2019.In Phase 1 clinical trials, SPR720 was administered at a single oral dose (100mg to 2,000 mg) and at a total repeated daily dose (500mg to 1,500 mg) for 7 to 14 days.In 7 SAD and 5 MAD cohorts, a total of 96 healthy volunteers (including healthy elderly volunteers aged 65 years or older) were randomly assigned to either SPR720 or placebo.The data indicated that SPR720 was generally well tolerated at doses up to 1,000 mg daily over a maximum study period of 14 days.In the phase I clinical trial, there were no serious adverse events, and all patients completed the trial.

SPR720 has also been evaluated in completed non-clinical GLP toxicology and safety pharmacology studies, including 28-day and 31-day GLP studies on non-human primates and rats, respectively. No significant findings were observed in these completed studies, and the results support the advancement of SPR720 to the currently completed phase I trial and the current phase IIa clinical trial, which is conducted under the supervision of the institutional review board under the effective IND .

Spr720 has been awarded the Qualified Infectious Disease Product (QIDP) designation by the FDA for the treatment of pulmonary infections caused by Mycobacterium tuberculosis (MTB) and pulmonary infections caused by Mycobacterium tuberculosis (MTB).It has been awarded the Orphan Drug designation by the FDA for the treatment of non-tuberculous mycobacterium (NTM) infection.The study of SPR720 in adults with NTM-PD has also been designated by the FDA as a rapid-progression program.Its intellectual property will be protected globally, including in the US and Europe, until 2033.