By DoM Communications | Date published: May 15, 2026
Mark Klempner Leads Phase I Study for Human Monoclonal Antibody for Lyme Disease
Mark Klempner, MD, professor of medicine, has led phase I of a clinical trial of a human monoclonal antibody discovered and developed at UMass Chan Medical School to prevent Lyme disease in the U.S. The antibody known as TNX-4800 (formerly known as mAb 2217LS) is a long-lasting borreliacidal (or bactericidal) that was well tolerated and showed lasting serum concentrations in participants, according to data presented by Dr. Klempner at the World Vaccine Congress 2026 in Washington, D.C.
According to Dr. Klempner, the study demonstrated potentially protective blood levels of TNX-4800 at two days, with protective blood levels sustained for at least four months due to its extended half-life design. Additionally, Dr. Klempner believes TNX-4800 has the potential to provide passive immunity by directly supplying neutralizing antibodies, bypassing the need for a vaccine to induce a patient’s immune system to generate its own antibodies, which can be associated with other issues.