Argenx's (ARGX) latest myositis data strengthened the outlook for efgartigimod, particularly in immune-mediated necrotizing myopathy, resulting in higher probability-of-success assumptions, Morgan Stanley said in a report Tuesday.
Efgartigimod produced a 15.4-point placebo-adjusted improvement in mean Total Improvement Score at week 52 across patients with IMNM and dermatomyositis. The treatment effect was similar in both subtypes, though the DM result did not reach statistical significance.
Morgan Stanley raised the probability of success for efgartigimod in IMNM to 90% and in DM to 65%. IMNM is viewed as the "near-term" and "higher-probability" opportunity, with the company's management planning to pursue a filing "with urgency" under Breakthrough Therapy Designation and seek priority review, according to the report.
The investment firm estimates myositis could contribute about $3.4 billion in worldwide risk-adjusted revenue by 2036, including about $1.8 billion from IMNM and $1.5 billion from DM.
Morgan Stanley has an overweight rating on Argenx and raised its price target to $1,230 from $1,200, saying the IMNM opportunity is "strong enough to stand on its own" while DM represents additional upside.
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