Prothena, the pharmaceutical company that produce the AL amyloidosis drug birtamimab, have announced that the Phase III AFFIRM-AL clinical trial failed to meet its primary endpoint – i.e., the main result being measured in the trial to determine whether the treatment was effective.

This means that the trial failed to demonstrate that newly diagnosed AL amyloidosis patients, with severe heart involvement (Mayo Stage IV), had an improved survival from taking birtamimab.

The AFFIRM-AL trial was also looking at two secondary endpoints, both of which were also not met. These were a 6-minute walk test distance and a Short Form-36 version 2 Physical Component Score. Both secondary endpoints were looking at the impact of birtamimab on patients’ physical function and ability to exercise.

In their press release, Prothena announced that they will no longer be developing birtamimab in AL amyloidosis because of the negative results. This includes stopping an open-label extension of the AFFIRM-AL clinical trial. If you have any questions or concerns, please speak to your doctor or nurse. You can also contact MPE at info@mpeurope.org.

What is birtamimab?

Birtamimab is a monoclonal antibody designed to bind to amyloid protein deposits, which accumulate in tissues and organs, leading to damage and eventual organ failure. By engaging the patient’s immune system, it was hoped that birtamimab would work to remove these harmful deposits from affected organs and tissues.

What was the AFFIRM-AL?

The Phase III AFFIRM-AL clinical trial was assessing the safety and effectiveness of birtamimab when given in combination with standard of care (SoC) chemotherapy in 207 newly diagnosed AL amyloidosis patients with Mayo Stage IV disease. Mayo Stage IV is the most severe stage of the disease, where the heart is significantly affected, making it harder for it to pump properly due to protein buildup.

Patients either received birtamimab in combination with SoC chemotherapy or placebo with SoC chemotherapy. SoC chemotherapy consisted of cyclophosphamide, bortezomib, and dexamethasone, with use of daratumumab permitted.

The “open label” part of the trial refers to a planned extension where patients would be able to receive the birtamimab for an additional 24 months or until the medication became available in their country. This extension of the trial has now been cancelled.

What are the next steps?

As Prothena have indicated they will no longer be developing birtamimab this means clinical trials exploring the drug will be discontinued. MPE will speak to Prothena to understand exactly what this means for patients who are currently enrolled in the clinical trial. In the meantime, if you have any questions or comments please speak to your doctor or nurse.

If you have any questions for MPE, please email info@mpeurope.org.

You can read the company’s press release here.