60 Degrees: Five Patients Improve, PCR Tests Negative in Relapsing Babesiosis Study
Key Facts
60 Degrees Pharmaceuticals announced on October 27, 2026, results for the first five patients to complete treatment in an expanded access program targeting relapsing babesiosis in immunocompromised patients. The company said all five patients reported improvement at study completion, while conventional PCR test results were negative for all of them. But the highly sensitive molecular test was negative in only 4 of the five patients after treatment. The results give the company an initial clinical and molecular signal from the program, which is testing tafenoquine in a high-risk population. The company said two additional patients remain on treatment, bringing total enrollment to 7.
The clinical improvement assessment was based on study completion forms, with the statement saying the five patients reported that they had “improved much” or “improved very much.” This reflects the patients’ own reports and is not an independent measure of symptoms or a result compared with a control group. At the molecular level, conventional PCR results were negative for everyone who completed treatment, while only four had a negative result on the highly sensitive NAT test. The difference between the results underscores the importance of not equating a negative PCR result with a negative result on the more sensitive test across the entire group. The figures are limited to five patients who completed treatment in an expanded access program, not a randomized trial.
The company describes the program as an open-label expanded access study of tafenoquine in high-risk patients with relapsing babesiosis whose previous treatment was unsuccessful. Treatment includes tafenoquine alongside conventional therapies, and treatment in the program may continue for up to 12 months. The company said the study includes standard-of-care regimens containing atovaquone, which does not mean all patients received the same combination. The target population is distinct because babesiosis may recur in people with immunosuppression. The Centers for Disease Control and Prevention says symptoms may appear or return months later, particularly in people who are immunocompromised or become immunocompromised later.
CDC guidelines generally recommend treating patients with a combination of atovaquone and azithromycin for at least 7 to 10 days. Treatment may last longer for immunocompromised patients; the guidelines indicate that treatment for severely immunocompromised patients may continue for 6 consecutive weeks or longer. They also note that data on treatment of relapse in this population are limited. In the regulatory context, no treatment or vaccine for human babesiosis is approved by the U.S. Food and Drug Administration. Tafenoquine is approved for malaria prevention, not for treating or preventing babesiosis.
Attention is turning to the company’s randomized trial in patients with severe acute babesiosis, which had enrolled 30 patients as of October 1, 2026. The study remained blinded after review by the data and safety monitoring board, according to the company. The company said on October 6 that primary and secondary endpoint results are expected in January 2027. It also plans to request a pre-IND meeting with the U.S. Food and Drug Administration that month regarding a supplemental new drug application. The January results are the next announced milestone in the babesiosis program, while the current expanded access results are drawn from the five patients who completed treatment.