Trouble Ahead for Alexion's Biosimilar Defense Strategy?

Drug maker Alexion has been seeing success with its strategy to defend against biosimilars, a plan that largely relies on transitioning patients with rare disease successfully treated with eculizumab (Soliris) to a longer-acting C5 inhibitor, ravulizumab (Ultomiris), before eculizumab faces oncoming biosimilar competition from products currently in phase 3 development.

According to Alexion’s third quarter financial results, approximately 51% of patients with paroxysmal nocturnal hemoglobinuria who were taking eculizumab have now been switched to ravulizumab, and an approval in atypical hemolytic uremic syndrome will see additional patients switch in the days ahead. The drug maker is also pursuing phase 3 clinical programs for the long-acting product in myasthenia gravis, as well as a subcutaneous version of the drug in multiple indications.

However, trouble may be ahead for Alexion; this month, Roche’s Japan-based subsidiary, Chugai Pharmaceutical, filed a patent infringement suit against Alexion in the District Court of Delaware.

The complaint alleges that ravulizumab infringes on Chugai’s technology that extends the half-life of an antibody in blood plasma, improving the length of time for which the antibody can bind to and neutralize an antigen. Chugai’s patent relates to a method of removing an antigen from blood plasma using antibodies with long half-lives in plasma, allowing antibodies to have longer durations of time during which they can bind to antigens.

According to the complaint, Chugai is developing “numerous medicines, including a C5 inhibitor,” that will use this proprietary approach and says that ravulizumab incorporates Chugai’s patented technology.

Furthermore, Chugai claims that Alexion tried to stop Chugai from obtaining the patent that is the subject of the complaint. Chugai says that an attorney—who did not at that time identify herself as working for Alexion—filed a third-party submission intended to keep the patent from issuing.

Chugai has asked for injunctive relief to prevent ravulizumab from being manufactured, used, or sold.

Another action brought by Chugai is also pending before the same court. That action is also related to proprietary antibody engineering technology, and Chugai seeks a judgement that ravulizumab infringes on Chugai’s US patents and asks the court to block US sales of the product.