Phase 2 B-FREE will test a 12‑week tafenoquine regimen in up to 100 patients with chronic babesiosis, measuring change at Day 90 on the MFI general fatigue subscale as the primary endpoint and tracking parasite eradication through longitudinal molecular assays. The design targets completion of at least 16 participants with Babesia infection confirmed at baseline using the FDA‑licensed RNA amplification test used by the American Red Cross, alongside CLIA‑validated RT‑PCR assays.
The immediate news is operational: the central site at Mount Sinai’s Cohen Center for Recovery from Complex Chronic Diseases is now open for enrollment, initiating what the sponsor calls the first interventional study dedicated to chronic babesiosis. The open‑label study will run roughly 12 months. Tafenoquine dosing follows the company’s ARAKODA regimen: loading on Days 1–4 and weekly administration from Day 11 through Day 89. Patients must have disabling fatigue for at least six months with other babesiosis‑consistent symptoms and laboratory evidence of Babesia exposure in the prior year. No FDA‑approved therapies currently exist for babesiosis.
Strategically, 60 Degrees Pharmaceuticals is attempting a dual objective: repurpose an approved antimalarial while defining and quantifying a controversial patient segment. Company estimates span from roughly 4,400 diagnosable U.S. cases annually with severe fatigue to as many as 190,000 if sensitive molecular testing supports broader prevalence. B-FREE is designed to adjudicate that gap by pairing a symptom-based primary endpoint with rigorous, repeated molecular confirmation using a highly sensitive, non-clinical NAT plus commercially available RT‑PCR tests. The open‑label, PRO‑led construct invites placebo and expectation effects, but the sponsor is betting that concordant signals across fatigue, parasitemia clearance, and assay performance will be compelling enough to inform the regulatory plan.
For sites, the study introduces several practical complexities. Screening is being performed outside New York to maintain compliance with state law and to avoid inadvertently revealing diagnostic results tied to the Red Cross NAT, which is not available for patient care. Monthly molecular testing for six months adds operational load and bioanalytics coordination. Tafenoquine’s 8‑aminoquinoline class requires G6PD testing and careful psychiatric history review, which can elongate screening and add safety monitoring burdens in a chronically symptomatic population. For labs and CROs, the protocol’s multi‑assay framework will generate data on sensitivity and concordance that could influence future diagnostic standards in tick‑borne disease trials. If chronic babesiosis is objectively confirmed at meaningful rates, payers and regulators may face pressure to formalize diagnostic and endpoint expectations beyond the acute, hospitalized setting.
The broader program context matters. A double‑blind, placebo‑controlled trial in hospitalized babesiosis patients has 19 of a minimum 24 randomized and targets an interim analysis in the second half of 2026 after the next tick season. An expanded access study for high‑risk relapsers is also running. The company plans a Type B FDA meeting in early 2026 to align on requirements for a supplemental NDA route. What to watch: the proportion of B-FREE enrollees with NAT‑confirmed infection, concordance between the Red Cross NAT and CLIA RT‑PCRs, and the relationship between parasitologic clearance and fatigue improvement. Recruitment pace will be constrained by seasonality and definitional controversy, and any safety signal will be amplified by tafenoquine’s long half‑life. Ultimately, regulatory viability may hinge less on symptom change alone and more on whether B-FREE and the randomized inpatient study together establish a consistent, objective efficacy narrative with an executable diagnostic playbook for routine care.
Jon Napitupulu is Director of Media Relations at The Clinical Trial Vanguard. Jon, a computer data scientist, focuses on the latest clinical trial industry news and trends.
