Roivant Sciences Ltd. / Pfizer Inc. / Priovant Therapeutics

Dermatomyositis and systemic lupus erythematosus (TYK2/JAK1 autoimmune)

322K US cases/yr · $6.5B Global SLE drug sales 2024 (USD MM, including Benlysta and Saphnelo) · 40 Percent of dermatomyositis patients with interstitial lung disease (%)

Disease Overview

Dermatomyositis (DM) is a rare idiopathic inflammatory myopathy with a US prevalence of approximately 21,000-25,000 patients (incidence ~9.6 per million) characterized by progressive proximal muscle weakness, pathognomonic skin findings (heliotrope rash, Gottron's papules), interstitial lung disease in ~30-40% of cases, and elevated cancer risk — with a 5-year survival around 75-85%. The only FDA-approved DM therapy at deal date was IVIG (Octagam 10%, approved July 2021); standard of care otherwise relied on systemic corticosteroids and off-label immunosuppressants (methotrexate, mycophenolate, azathioprine, rituximab, JAK inhibitors). Systemic lupus erythematosus (SLE) is a far larger, heterogeneous autoimmune disease affecting ~200,000-322,000 US patients (Lupus Foundation of America 2021 estimate ~1.5 million globally, ~322,000 US definite + probable). SLE biologics included Benlysta (belimumab, GSK, approved 2011 for SLE and 2020 for lupus nephritis) and Saphnelo (anifrolumab, AstraZeneca, approved Aug 2021); but the bulk of patients still relied on hydroxychloroquine, corticosteroids and broad immunosuppressants with substantial cumulative toxicity. The mechanistic appeal of brepocitinib was its dual TYK2 + JAK1 inhibition, blocking IFN, IL-12/23 and γc-cytokine signaling cascades implicated across both DM and SLE pathogenesis.

Competitive Landscape

Brepocitinib (PF-06700841) was a first-in-class oral dual TYK2/JAK1 inhibitor with broad autoimmune activity. At deal date in Sep 2021, the most relevant TYK2-pathway competitor was BMS-986165 (deucravacitinib, BMS), a selective allosteric TYK2 inhibitor in Phase 3 POETYK PSO-1/PSO-2 in psoriasis (subsequently approved Sep 2022 as Sotyktu) with parallel Phase 2 trials in SLE (PAISLEY) and Phase 2 in psoriatic arthritis. Pan-JAK and JAK1-selective competitors with autoimmune labels included Xeljanz (tofacitinib, Pfizer, RA/UC/PsA/AS but with FDA black box on cardiovascular events Feb 2021), Olumiant (baricitinib, Lilly, RA/COVID-19/alopecia areata), Rinvoq (upadacitinib, AbbVie, RA/PsA/AD/UC/AS), Cibinqo (abrocitinib, Pfizer, AD), and Jakafi (ruxolitinib, Incyte/Novartis, MF/PV/cGVHD). For dermatomyositis specifically, the post-deal competitive landscape evolved toward Octagam IVIG (Octapharma, FDA-approved July 2021 for adult DM), Argenx's efgartigimod (Vyvgart, in DM Phase 2/3 ALKIVIA), and Cabaletta's CABA-201 (CD19 CAR-T). For SLE, Saphnelo (anifrolumab, anti-IFNAR1) was approved Aug 2021, Benlysta (belimumab) was the only other biologic on label, and emerging mechanisms included anti-CD38 (daratumumab investigator-initiated), anti-CD20 (rituximab off-label, obinutuzumab Roche Phase 3), low-dose IL-2 (Iltoo, Cugene), and CD19 CAR-T (Cabaletta CABA-201, Caribou CB-010, BioNTech BNT211). Brepocitinib's Phase 3 in DM (VALOR) read out positive in 2024 with a sBR-IGA response benefit; Phase 3 in SLE was discontinued in mid-2024 after Phase 2b failure.