Two international clinical studies have demonstrated that sutezolid and delpazolid, both members of the oxazolidinone antibiotic class, offer significantly safer alternatives to linezolid for tuberculosis treatment while maintaining strong antimicrobial activity. The Phase 2b trials, led by PD Dr. Norbert Heinrich at the Institute of Infectious Diseases and Tropical Medicine at LMU University Hospital Munich, were published on July 8, 2025, in The Lancet Infectious Diseases.
Addressing Linezolid's Toxicity Challenge
The World Health Organization introduced linezolid in 2022 as part of the BPaLM regimen (bedaquiline, pretomanid, linezolid, and moxifloxacin) as the standard 6-month treatment for multidrug-resistant tuberculosis, reducing treatment duration from the previous 18-month standard. However, linezolid's prolonged use frequently leads to serious adverse events including anemia and optical neuropathy, which can be irreversible and may require treatment discontinuation.
"Despite its effectiveness, linezolid is simply too toxic for many patients. We urgently need safer alternatives in this antibiotic class," said PD Dr. Norbert Heinrich.
Innovative Trial Design and Results
The SUDOCU (PanACEA Sutezolid Dose-finding and Combination Evaluation) and DECODE (PanACEA DElpazolid Dose-finding and COmbination DEvelopment) trials were conducted in South Africa and Tanzania as part of the PanACEA network. These Phase 2b, open-label, randomized studies were the first to test these specific four-drug combinations, systematically comparing different dosing levels to evaluate antibacterial activity, drug exposure, and safety profiles.
Sutezolid Findings
Sutezolid demonstrated strong antibacterial activity and was well tolerated across all tested doses in patients with drug-sensitive pulmonary tuberculosis. Critically, no cases of nerve damage or blood toxicity were observed, representing a significant advantage over linezolid. While the results suggest sutezolid could be a safer alternative for future TB treatment regimens, particularly for long-term use, researchers noted that no final dose recommendation can be made yet.
Delpazolid Results
Delpazolid enhanced the effectiveness of the combination regimen with bedaquiline, delamanid, and moxifloxacin. A once-daily dose of 1200 mg achieved the desired drug levels for maximum efficacy and was well tolerated over 16 weeks. Importantly, no cases of nerve damage or blood-related side effects were observed at this dose.
"These findings suggest that both drugs may offer safer treatment options for TB patients, particularly those requiring longer courses of therapy," noted Dr. Tina Minja, National PI for the DECODE study at NIMR-Mbeya Medical Research Centre in Tanzania.
Global Collaborative Effort
The studies were conducted through the Pan-African Consortium for the Evaluation of Anti-Tuberculosis Antibiotics (PanACEA) network, which includes clinical and academic partners across Africa and Europe. Research partners included the German Center for Infection Research (DZIF), the Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, the Center for International Health at LMU University Hospital, Helmholtz Munich, and Radboud University Medical Center from the Netherlands.
Elin Svensson, senior researcher from Radboud University Medical Center who led the data analysis in both studies, emphasized the collaborative nature of the achievement: "These findings are encouraging and show there is hope for better drugs for drug-resistant TB. Without the collaboration within PanACEA, this would not have been possible in such a short time."
Future Research Directions
The publication in The Lancet Infectious Diseases underscores the scientific relevance of these results and their potential to shape future TB treatment strategies. "Seeing fewer side effects with sutezolid and delpazolid is a significant step forward—it brings us closer to TB therapies that are both effective and easier for patients to tolerate," commented Dr. Ivan Norena, medical team lead at the Institute of Infectious Diseases and Tropical Medicine at LMU University Hospital Munich.
Further research is now planned to evaluate both drugs in larger cohorts and in fully optimized treatment combinations. If the promising results are confirmed in larger studies, these drugs could play a critical role in the next generation of TB therapies, helping to reduce treatment-related side effects while maintaining efficacy.
