2025-06-12-Jefferies-阿根克斯（ARGX）_ARGX_关于EULAR会议上肌炎和干燥综合征数据的思考_14页_3mb

ARGX: Summary of Myositis & Sjogren's Data at EULAR

Core Content

Argenx (ARGX) presented full Phase 2 (Ph.2) data for efgartigimod in myositis and Sjogren's Syndrome at EULAR, providing key insights into the drug's efficacy and risk profile.

Key Highlights

Myositis (ALKIVIA Study)

• Efficacy: Efgartigimod (efgar) demonstrated statistically significant (p=0.0004) pbo-adjusted mean Total Improvement Score (TIS) of ~14.8 at week 24, with a 50.45 tx vs 35.65 pbo.
• Secondary Endpoints:
  • Proportion of patients achieving moderate (TIS ≥40) and major (TIS ≥60) clinical improvement were significantly higher (78.7% vs 47.6% and 34.0% vs 9.5%, respectively).
  • Median time to TIS ≥20 was 30 days vs 71.5 days for pbo; median time to TIS ≥40 was 113 days vs not estimable for pbo.
• Clinical Relevance: Efficacy on TIS ≥40 and ≥60 is considered more clinically relevant than TIS ≥20.
• Population & Trial Design:
  • The study included 3 myositis subtypes: Immune-Mediated Necrotizing Myositis (IMNM), Dermatomyositis (DM), and Antisynthetase Syndrome (ASyS) (n=89).
  • ARGX did not break out efficacy by subtype, making it difficult to compare with IVIG's ProDERM trial (DM only, week 16 endpoint).
  • ARGX is advancing the Ph.3 portion of ALKIVIA with a larger population (n=150) and a 52-week endpoint.
  • A new steroid tapering protocol is being introduced in Ph.3, which requires further evaluation for pbo risk.
• Safety: AE profile was consistent with previous subcutaneous (subQ) trials, with common AEs including injection site erythema (~23%), rash (~17%), bruising (~11%), and diarrhea (~13%). Two deaths were reported, but both were deemed unrelated to treatment.

Sjogren's Syndrome (RHO Study)

• Efficacy: Efgartigimod showed consistent clinESSDAI benefit at similar IgG drops as nipo (15mg/kg Q2W), with a pbo-adjusted delta of ~3 points (efgar vs nipo).
• Trial Design: The Ph.2 RHO trial included 34 patients (2:1 randomization) with primary SS, ESSDAI ≥5, clinESSDAI ≥6, and residual salivary flow.
• Baseline Characteristics:
  • Efgar had a median clinESSDAI score of 13 vs 18 for pbo.
  • Patients in RHO were more severely affected than in JNJ's trial, but the data remains consistent with nipo.
• Risks:
  • Sjogren's is considered a risky indication due to the uncertainty of whether the ~3-point clinESSDAI delta will hold in Ph.3.
  • The Ph.3 trial (UNITY) will have a larger population (n=580) and use clinESSDAI as the primary endpoint.

Main Viewpoints

• Myositis: The data is encouraging, with a clear separation from pbo across multiple endpoints, though it is not an apples-to-apples comparison with IVIG due to population differences.
• Sjogren's: The data supports the FcRn mechanism of action, but the indication remains risky due to the potential for effect size reduction in Ph.3 and the lack of clear pbo risk mitigation.
• Investment Thesis: ARGX is rated as a Buy due to its strong performance, promising clinical readouts, and the potential for label expansion and pipeline upside.
• Market Opportunity: The company is seen as a best-in-class anti-FcRn therapy with significant market potential for current indications and future label expansions.

Financial Outlook

• Price Target: $772 (up +32% from prior close)
• Market Cap: $38.5B
• Float (%) | ADV MM (USD): 92.2% | 239.27

Investment Scenarios

• Base Case: $772
• Upside Scenario: $800 (+36%)
• Downside Scenario: $400 (-32%)

Pipeline Overview

• Efgartigimod: 100% POS for gMG and CIDP, 70% POS for IMNM, 40% for ASyS and DM, 30% for Sjogren's.
• Other Pipeline Products: Includes C2 inhibitor ARGX-117, which represents additional upside potential.

ESG & Company Goals

• Mission: Deliver innovative treatments for rare autoimmune diseases to patients globally.
• Engagement: Work with patients, supporters, and advocacy communities to improve lives.

Questions to Management

1. What is the current engagement with myasthenia gravis advocacy groups and plans for expansion?
2. What is the strategy for expanding partnerships beyond the disclosed autoimmune indications?

Conclusion

The data from EULAR provides incremental positive signals for efgartigimod in myositis and supports its FcRn mechanism in Sjogren's. While the myositis data is encouraging, the lack of subset analysis and potential pbo risk in Ph.3 remain concerns. Sjogren's is viewed as a promising but risky indication. Overall, Argenx is positioned for sustainable growth with a strong pipeline and potential for commercial success.