Morning Coffee: ALKIVIA Ph3, A Defining Moment In Myositis?

Research evidence excerpt

Morning Coffee: ALKIVIA Ph3, A Defining Moment In Myositis?

TD Cowen argenx

Global Research June 11, 2026

and related tRNA synthetase antibodies marking a more mixed humoral-cellular

disease in which lung involvement is often the dominant driver.

IMNM is the most muscle-centric and, in our view, the cleanest FcRn subtype, defined

by rapid severe proximal weakness, markedly elevated CK, minimal extra-muscular

disease, and anti-SRP or anti-HMGCR autoantibodies that appear highly IgG-driven

and directly pathogenic. This subtype differentiation matters because TIS is weighted

most heavily toward muscle and global activity measures, suggesting that muscle-

dominant subtypes such as IMNM and muscle-active DM should be best positioned

to show strong numeric separation.

Ph2 ALKIVIA+ OLE Provides Confidence For Long-Term Durability Of Response At

52 Weeks

As discussed in our note on argenx's myositis data presented at EULAR last week,

ALKIVIA+ is an OLE of the randomized Ph2 ALKIVIA study evaluating Vyvgart Hytrulo

(1000mg, SC QW) in patients with myositis (DM, IMNM, PM, including ASyS) on

background therapy. Patients completing the 24-week placebo-controlled portion

could either continue onto Vyvgart Hytrulo or switch from placebo, with outcomes

assessed through Week 52 using Total Improvement Score (TIS). Recall, this is a

composite endpoint capturing muscle strength (MMT8), physician and patient global

assessments, physical function, muscle enzymes, and extramuscular activity.

In ALKIVIA+, mean TIS improved progressively with sustained benefit through Week

52, reaching 52-points (from 51-points at 24 wks) in continuous-treatment patients

and 50-points in placebo-switch patients (from 39 points at 24 wks), supporting