TBD09, a tuberculosis drug candidate discovered by Merck (MSD), is emerging as a potential safer alternative to linezolid in modern TB treatment regimens.
How TBD09 Was Discovered?
TBD09, originally MK-7762, was discovered under the TB Drug Accelerator programme, a global collaboration involving biopharma companies, research institutes, and universities.
The Gates Foundation played a central role in accelerating discovery and early development.
Why a New TB Drug Is Needed?
Tuberculosis remains the world’s deadliest infectious disease.
- 10.7 million infections reported globally in 2024
- 1.23 million deaths, despite TB being preventable and curable
- Standard treatment requires multiple antibiotics for at least six months
Drug resistance often develops when treatment is interrupted early.
WHO-Recommended TB Regimens—and Their Limitation
In 2022, WHO endorsed BPaL and BPaLM regimens for drug-resistant TB.
These regimens:
- Reduced treatment duration from 18 months to 6 months
- Delivered significantly improved cure rates
However, they rely heavily on linezolid.
The Linezolid Problem
Linezolid is highly effective against Mycobacterium tuberculosis, but many patients cannot tolerate long-term use.
Common limitations include:
- Bone marrow suppression
- Reduced blood cell production
- Peripheral neuropathy
These toxicities often force dose reduction or discontinuation.
What Makes TBD09 Different?
TBD09 belongs to the oxazolidinone class, like linezolid, but shows promising improvements.
Preclinical and early data show:
- Activity against drug-sensitive and drug-resistant TB isolates
- Comparable bactericidal activity to linezolid
- Potential for better tolerability
Findings were published by researchers from NIH, Merck, and Gates MRI in Nature Medicine.
Clinical Progress So Far
- Phase 1 trial completed, evaluating safety and pharmacokinetics
- Second Phase 1 trial launched in September 2025
- Development led by Gates Medical Research Institute (MRI)
Merck licensed TBD09 to Gates MRI to support affordable TB regimens.
Regulatory Momentum
As TBD09 moves toward Phase 2 evaluation, the US FDA has granted:
- Qualified Infectious Disease Product (QIDP) designation
- Fast Track designation
These provide eligibility for priority review, reflecting urgent unmet need.
The Bigger Picture
According to Gates MRI leadership, TBD09 highlights how cross-sector collaboration can rebuild the TB drug pipeline.
If successful, TBD09 could:
- Replace or reduce linezolid exposure
- Improve treatment tolerability
- Strengthen next-generation TB combination regimens
