30-day benznidazole regimen matches standard efficacy with fewer side effects in Chagas disease trial
Primary endpointSustained parasitological clearance (all-negative qPCRs for at least four of seven timepoints, 4-36 months)
Where these numbers come from
“Of 435 participants included in the mITT population, sustained parasitological clearance up to 36 months was seen in 69 (95%) of 73 participants in the benznidazole 60-day group (standard of care), 68 (94%) of 72 in the benznidazole 30-day group, 69 (92%) of 75 in the benznidazole 90-day group, 58 (81%) of 72 in the nifurtimox 60-day group (standard of care), 63 (89%) of 71 in the nifurtimox 30-day group, and 65 (90%) of 72 in the nifurtimox 90-day group.”
The publication
In a phase 2b trial of adults with chronic Chagas disease, benznidazole 150 mg once daily for 30 days was non-inferior to the standard 150 mg twice daily for 60 days for sustained parasitological clearance. The shorter regimen also had a significantly lower rate of drug-related adverse events, with 37% of participants experiencing side effects compared to 60% in the standard group.
Who the findings apply to
The trial included adults aged 18 to 50 years weighing between 40 and 90 kg.
Participants had serologically and quantitative PCR-confirmed chronic Trypanosoma cruzi infection.
Eligible patients were in the indeterminate or early cardiac form of the disease.
Why this matters
Standard treatments for chronic Trypanosoma cruzi infection often cause adverse events that lead to treatment interruption. This trial demonstrates that a halved-dose, shortened benznidazole regimen maintains efficacy while improving tolerability, which could support its adoption as a preferred regimen. However, the authors note that phase 3 trials are required to confirm long-term efficacy across different parasite genotypes and settings before it can be incorporated into treatment guidelines.
What the study found
Sustained parasitological clearance up to 36 months was observed in 95% of the benznidazole 60-day standard of care group and 94% of the benznidazole 30-day group.
The prespecified primary longitudinal analysis supported non-inferiority for the benznidazole 30-day group versus the standard of care, with a risk difference of -2.0 (97.5% CI -5.41 to 1.45).
Fewer participants in the benznidazole 30-day group had drug-related adverse events (37%) than in the benznidazole 60-day standard of care group (60%), a risk difference of -23 percentage points (95% CI -38 to -7).
No other comparison between experimental and standard of care groups was statistically significant for adverse events.
What the result does not establish
The trial was an open-label, non-inferiority phase 2b study conducted at three sites in Bolivia.
The primary efficacy outcome was assessed in a modified intention-to-treat population of participants with at least four follow-up qPCR results between 4 and 36 months.
The authors state that phase 3 trials are required to support the incorporation of the 30-day regimen into treatment guidelines.
Most drug-related adverse events arose within 10 to 14 days regardless of treatment duration, suggesting idiosyncratic rather than cumulative toxicity.
Authors’ conclusion
“Benznidazole 150 mg once daily for 30 days showed non-inferior efficacy and the lowest rate of drug-related adverse events among the regimens tested, supporting its adoption as the preferred benznidazole regimen for chronic Chagas disease; phase 3 trials of long-term efficacy across parasite genotypes and settings are required to support its incorporation into treatment guidelines. The early, duration-independent…”
Study and sources
Efficacy and safety of alternative benznidazole and nifurtimox regimens for adults with chronic Trypanosoma cruzi infection (TESEO): an open-label, randomised, non-inferiority phase 2b trial
Randomised trial · Phase 3 · Lancet Infectious diseases · 2026-09-22
Sources and limitations
- PubMed record PMID 42772313 (PubMed / NLM · 2026-09-23)
- Trial registry NCT03981523 (ClinicalTrials.gov · 2026-09-23)
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