Credit: Humane World for Animals

Humane World for Animals and Humane World Action Fund encouraged by draft guidance on monoclonal antibody therapies, but further clarity needed from federal drug regulators

December 3, 2025 - WASHINGTON - Humane World for Animals and Humane World Action Fund (formerly called the Humane Society of the United States and Humane Society Legislative Fund) are pleased to see new draft guidance from the U.S. Food and Drug Administration to reduce testing on non-human primates for monoclonal antibodies and will be submitting comments in response.

Monoclonal antibodies are laboratory-made proteins designed to mimic the human immune response with precise specificity. These antibodies are commonly developed as therapies for cancer and autoimmune diseases and can be designed to bind to targets only found in people. Depending on the target, the antibodies can block cancer cell growth, deliver treatment directly to diseased cells, or modify the immune response.

“We’re encouraged that this draft guidance, which if adopted will decrease the number of primates used for testing, reflects the FDA’s stance that non-animal methods can deliver better, more reliable data for drug therapies. We urge FDA to take additional, meaningful steps so that more humane, science-driven methods become the norm rather than the exception, as FDA has stated it is seeking,” said Kathleen Conlee, vice president, Animal Research Issues at Humane World for Animals.

“Saving human lives doesn’t need to come at the expense of animals’ lives. We welcome today’s announcement by the FDA and will continue our longstanding advocacy including encouraging FDA to grant our regulatory petition seeking clarification for the use of modern, humane alternatives across the board,” said Tracie Letterman, vice president, Federal Affairs at Humane World Action Fund.

For years, Humane World for Animals and Humane World Action Fund have led efforts to modernize drug testing by urging the FDA to prioritize non-animal testing methods. Through a regulatory petition submitted last year, we pushed for  amendments to clarify that animal testing is not legally required for drugs under the Federal Food, Drug, and Cosmetic Act. The petition also requested that the agency create a guidance document focused on non-animal methods. This suggestion for guidance was incorporated into a roadmap published by the FDA in April 2025.

Source: Humane World for Animals and Humane World Action Fund