Ra Pharmaceuticals’ Phase III C5 inhibitor PNH trial should have switching design in Soliris-suboptimal population to meet recruitment obstacles - experts
Ra Pharmaceuticals’ (NASDAQ:RARX) potential Phase III trial of C5 inhibitor RA101495 in paroxysmal nocturnal hemoglobinuria (PNH) patients should have a switching design in patients demonstrating suboptimal response to the standard order of care (SOC) to overcome patient recruitment difficulties, experts said.
Analysts have not commented on Phase III design, however, experts said a randomised head-to-head comparator trial with the SOC, Alexion Pharmaceuticals' (NASDAQ:ALXN) Soliris (eculizumab), in treatment-naïve patients would produce the most clinically meaningful data. However, such a trial is unlikely to run because it would have to be impracticably large to meet statistical significance requirements, they explained. Instead, a switching trial will likely be acceptable to the FDA given its approval of Alexion’s similarly designed Phase III PNH study (NCT03056040), switching patients from Soliris to ALXN1210, a longer-acting anti-C5 antibody, they said.
Experts added the trial will be difficult to recruit for because of PNH’s rarity. One said Ra will need to enrol about 50 clinical sites to meet requirements, focusing especially on countries with centralised clinics such as the UK and Netherlands.