Alexion's long-acting C5 inhibitor meets in Phase III

Alexion Pharmaceuticals Inc. (NASDAQ:ALXN) said Thursday that ALXN1210, its long-acting formulation of Soliris eculizumab, met the co-primary and four key secondary endpoints in the Phase III ALXN1210-PNH-301 trial to treat paroxysmal nocturnal hemoglobinuria (PNH). The company reiterated its plans to submit regulatory applications for ALXN1210 next half in the U.S., EU and Japan to treat PNH.

Buysiders have been on the lookout for the ALXN1210 data. International Biotechnology Trust plc's Ailsa Craig previously told BioCentury that ALXN1210 “is a product that they hope will replace Soliris so that they can maintain their monopoly on the space" (see BioCentury, Jan. 5).

Alexion's Soliris, a humanized mAb targeting complement 5 (C5), is approved in the U.S., EU and Japan to treat PNH and atypical hemolytic uremic syndrome (aHUS) and in the EU for generalized myasthenia gravis.

The open-label trial enrolled 246 patients with complement inhibitor-naïve PNH to receive IV ALXN1210 every eight weeks or Soliris every two weeks for 26 weeks. On the trial's co-primary endpoints, ALXN1210 was non-inferior to Soliris in the proportion of patients who achieved transfusion avoidance (73.6% vs. 66.1%) and who achieved normalization of lactate dehydrogenase (LDH) levels (53.6% vs. 49.4%, OR=1.19, 95% CI: 0.8, 1.77) at week 26.

ALXN1210 was also non-inferior to Soliris on the four key secondary endpoints of the percent change from baseline in LDH levels at week 26 (76.8% vs. 76%); the change from baseline in Functional Assessment of Chronic Illness Therapy (FACIT)-Fatigue scale score (7.1 vs. 6.4 points); the proportion of patients with breakthrough hemolysis (4% vs. 10.7%); and the proportion of patients with stabilized hemoglobin levels (68% vs. 64.5%).

The trial protocol also pre-specified breakthrough hemolysis as the first endpoint tested for superiority. ALXN1210 was not superior to Soliris on the endpoint (p=0.074), and no other endpoints were tested for superiority.

Alexion expects data next quarter from the Phase III ALXN1210-PNH-302 trial of ALXN1210 in PNH patients who are clinically stable on Soliris for at least six months, and data in 4Q18 from a Phase III trial of ALXN1210 in complement inhibitor-naïve patients with aHUS.

Alexion gained $4.15 to $126.83 on Thursday.