Anti-Drug Antibodies (ADAs) and Anti-NGF Pain Medicines: A Simple Explanation

Anti-NGF medicines are a newer type of pain treatment. They are made to help reduce pain by blocking a natural protein in the body called nerve growth factor, or NGF. NGF helps send pain signals to the brain. When NGF is blocked, pain signals can be quieter.

In veterinary medicine, anti-NGF medicines are already used for pets. For dogs, this medication is called Librela (or Beransa in Australia), and its generic name is bedinvetmab. For cats, the medication is called Solensia, and its generic name is frunevetmab. These medicines are given as injections and are used to help manage arthritis pain.

These medicines are made from proteins called monoclonal antibodies. Because they are proteins, the immune system may sometimes notice them and react.

One way the body can react is by making anti-drug antibodies, also called ADAs. ADAs are immune proteins that form in response to a medicine. They can attach to the drug and sometimes make it work less well. In rare cases, they may be linked to side effects.

Making ADAs does not automatically mean a medicine is unsafe. Many people and animals can make ADAs and still do very well on the drug. Some never have side effects at all.

In human medicine, doctors often test for ADAs when people take monoclonal antibody drugs, including anti-NGF medicines. This is because people may take these drugs for a long time. ADA testing helps doctors understand whether a reaction or change in how well the drug works might be related to the immune system. In short, ADAs are a tool to help study immune reactions.

In veterinary medicine, ADA testing is not required for pets. It can be very expensive and time consuming to create an ADA test. Safety is checked in other ways with veterinarians focusing on what they can see in the patient, such as pain, swelling, fever, behavior changes, bone or cartilage changes, and overall health. Additionally, laboratory tests (blood tests, x-rays, etc.) can be done as part of monitoring. If a drug causes harm, it should show up in these real-life signs.

Sometimes it does not show up until a necropsy (animal autopsy) is done, but these are rarely done in veterinary medicine.

Testing for ADAs in pets is also difficult because each animal species would need its own special test.

ADAs help researchers understand how biologic drugs interact with the immune system, but they are not a required test for pet safety.

The most important question is simple: does the medicine help the pet feel better and move more comfortably, and does it do so safely?

That answer comes from careful observation, open communication with your veterinarian, and ensuring we don’t do harm.