Idiopathic Inflammatory Myositis - Market Insights, Epidemiology, and Market Forecast - 2034

Key Highlights

• According to the analyst's estimates, in 2023, there were approximately 191,589 diagnosed prevalent cases of idiopathic inflammatory myositis in the 7MM. Of these, the United States accounted for 48% of the cases, while EU4 and the UK accounted for nearly 38% and Japan represented 14% of the cases, respectively.
• The idiopathic inflammatory myositis market is poised for rapid growth, with a strong compound annual growth rate (CAGR) projected from 2024 to 2034. This expansion across the 7MM will be driven by the launch of innovative therapies, including dazukibart (PF 06823859), efgartigimod, SAPHNELO (anifrolumab), brepocitinib, and HIZENTRA, among others. Additionally, the rising prevalence of cases, fueled by risk factors like genetic predisposition, viral infections, and UV radiation, is expected to further boost demand for effective treatments.
• According to the analyst's analysis, the idiopathic inflammatory myositis market in the 7MM was valued at approximately USD 447 million in 2023. Over the forecast period from 2024 to 2034, this market is projected to grow at a CAGR of 21.1%.
• Octapharma, Pfizer, and Mitsubishi Tanabe Pharma have been leading players in the idiopathic inflammatory myositis market, offering approved treatments like OCTAGAM 10% in the US and EU, and VENOGLOBULIN-IH 5% in Japan.
• Current treatments for idiopathic inflammatory myositis, like corticosteroids and Disease-modifying Antirheumatic Drugs (DMARDs), can be ineffective for some patients and cause side effects. There is a critical need for more targeted therapies that address immune dysregulation with fewer adverse effects.

This report delivers an in-depth understanding of idiopathic inflammatory myositis, historical and forecasted epidemiology, as well as the idiopathic inflammatory myositis market trends in the United States, EU4 (Germany, France, Italy, and Spain) and the United Kingdom, and Japan.

The idiopathic inflammatory myositis market report provides current treatment practices, emerging drugs, market share of individual therapies, and current and forecasted 7MM idiopathic inflammatory myositis market size from 2020 to 2034. The report also covers idiopathic inflammatory myositis treatment practices/algorithms and unmet medical needs to curate the best opportunities and assess the market’s potential.

Idiopathic Inflammatory Myositis Understanding and Treatment Algorithm

Idiopathic inflammatory myositis overview

Myositis, literally meaning “muscle inflammation,” refers to a diverse group of diseases characterized by inflammation of striated muscle tissue. Idiopathic Inflammatory Myopathies (IIM) are a subset of these conditions, marked by chronic muscle inflammation, weakness, and, in some cases, pain.

Inflammatory myopathies can take various forms based on their underlying cause, including infectious, autoimmune, drug-induced, and idiopathic myositis, as well as myositis associated with other conditions like inclusion body myositis and myositis ossificans. IIM encompasses conditions such as dermatomyositis, polymyositis, overlap myositis, sporadic inclusion body myositis (sIBM), and Necrotizing Autoimmune Myopathy (NAM).

Though rare, IIM can affect both adults and children, with patients typically presenting with sub-acute to chronic proximal muscle weakness, making activities like rising from a chair, climbing stairs, lifting objects, or combing hair difficult.

In addition to muscle weakness, myositis patients may experience a variety of other symptoms, which can even be the primary manifestation of the disease for some individuals. These include inflammatory arthritis, interstitial lung disease, and skin rashes.

Idiopathic inflammatory myositis diagnosis

Diagnosing myopathies involves a laboratory evaluation, imaging studies, multidisciplinary consultations, histologic examination, and potentially genetic studies. In the cases of immune-mediated necrotizing myopathy and Inclusion body myositis, the concept of inflammation must be rethought.

Idiopathic inflammatory myositis treatment

The main goals of IIM therapy are to restore muscle strength, limit/eliminate inflammation, and prevent other organ damage. It is ideal if the treatment involves a multidisciplinary approach; neurology, rheumatology, dermatology, pulmonary, physical occupational, and speech therapy.

The current therapeutic landscape in idiopathic inflammatory myositis overall includes the use of corticosteroids, including prednisolone, immunoglobulins including OCTAGAM 10%, immunosuppressants like methotrexate, mycophenolate, azathioprine, and biologics, including rituximab, abatacept, and TNF inhibitors.

Idiopathic Inflammatory Myositis Epidemiology

As the market is derived using a patient-based model, the Idiopathic Inflammatory Myositis epidemiology chapter in the report provides historical as well as forecasted epidemiology segmented by total diagnosed prevalent cases of idiopathic inflammatory myositis, type-specific diagnosed prevalent cases of idiopathic inflammatory, gender-specific diagnosed prevalent cases of idiopathic inflammatory, and age-specific diagnosed prevalent cases of idiopathic inflammatory myositis in the 7MM covering the United States, EU4 countries (Germany, France, Italy, and Spain) and the United Kingdom, and Japan from 2020 to 2034.

• The total diagnosed prevalent cases of idiopathic inflammatory myositis in the 7MM were approximately 191,589 cases in 2023, which are expected to increase during the forecast period (2020-2034).
• In 2023, the US accounted for the highest diagnosed prevalent cases of idiopathic inflammatory myositis with approximately 91,734 cases, which are expected to increase by 2034.
• Among EU4 and the UK, Germany had the highest diagnosed prevalent cases of idiopathic inflammatory myositis with nearly 21,781 cases in 2023, followed by France with around 17,475 cases. On the other hand, Spain accounted for the least with nearly 6,235 cases.
• In 2023, Japan accounted for approximately 26,094 diagnosed prevalent cases of idiopathic inflammatory myositis which are expected to increase by 2034.
• In 2023, among the type specific diagnosed prevalent cases of idiopathic inflammatory myositis, the US accounted for approximately 30,649 cases for polymyositis, 38,517 cases for dermatomyositis, and 22,569 cases for inclusion body myositis.
• In 2023, Germany had approximately 8,712 males and 13,069 females diagnosed with idiopathic inflammatory myositis.
• In 2023, the diagnosed prevalent cases of idiopathic inflammatory myositis across the age groups 0-17 years, 18-44 years, 45-64 years, and 65 years and older were approximately 1,044, 7,959, 9,655, and 7,437, respectively, in Japan.

Idiopathic Inflammatory Myositis Drug Chapters

The drug chapter segment of the idiopathic inflammatory myositis report encloses a detailed analysis of idiopathic inflammatory myositis-marketed drugs and mid to late-stage (Phase III and Phase II) pipeline drugs. It also helps understand the idiopathic inflammatory myositis clinical trial details, expressive pharmacological action, agreements and collaborations, approval and patent details, advantages and disadvantages of each included drug, and the latest news and press releases.

Marketed Drugs

OCTAGAM 10% (Intravenous Immune Globulin [Human]): Octapharma/Pfizer

OCTAGAM 10%, manufactured by Octapharma Pharmazeutika Produktionsges and distributed by Pfizer, is an intravenous immunoglobulin (IgG) solution derived from human plasma. Approved by the US FDA in July 2021, it is specifically indicated for the treatment of adult dermatomyositis, a rare autoimmune condition affecting muscle strength and skin. This medication helps improve muscle function and reduce skin rashes in affected patients. It has also received orphan drug designation from the US FDA. In Europe, OCTAGAM 10% was granted approval in June 2021 as an immunomodulatory therapy for dermatomyositis in adults, with national approval in Germany following in May 2021. The medication can be administered in hospitals, infusion centers, or at home.

VENOGLOBULIN-IH 5% IV (Human Immunoglobulin G): Mitsubishi Tanabe Pharma

VENOGLOBULIN-IH, developed by Mitsubishi Tanabe Pharma, is a human immunoglobulin derived from donated plasma, designed to address muscle weakness in patients with polymyositis or dermatomyositis who exhibit insufficient response to steroids. Domestic clinical studies demonstrated significant improvements in muscle strength and daily activity scores in these patients following treatment. The safety profile of VENOGLOBULIN-IH was found to be comparable to that of existing therapies. It has received orphan drug designation in Japan for the treatment of polymyositis and dermatomyositis. VENOGLOBULIN-IH was approved in Japan in October 2010 for treating muscle weakness in patients with these conditions who do not respond adequately to steroid therapy. The medication is administered intravenously.

Emerging Drugs

Dazukibart PF-06823859 (anti-beta interferon): Pfizer

Dazukibart (PF-06823859) is a potent humanized IgG1K monoclonal antibody in development for the treatment of moderate to severe dermatomyositis and polymyositis. As a selective interferon (IFNß1) blocker, it targets and inhibits the IL-23 cytokine, a key mediator in the immune response associated with autoimmune diseases. Administered via intravenous and subcutaneous injection, Dazukibart is designed to modulate immune activity in these conditions. It has received orphan drug designation and prime drug designation from the European Medicines Agency (EMA) for dermatomyositis. In the US, it holds both orphan drug and fast-track designations for the same indication.

Currently, dazukibart is in Phase III clinical trial for dermatomyositis and polymyositis.

Efgartigimod: Argenx

Efgartigimod is a first-in-class investigational antibody fragment designed to target the neonatal Fc receptor (FcRn). It is being explored for the treatment of severe autoimmune diseases associated with pathogenic immunoglobulin G (IgG) and IgG autoantibodies, where significant unmet medical needs exist. Already approved as VYVGART in the US, Europe, and Japan for the treatment of generalized Myasthenia Gravis (gMG) in adult anti-acetylcholine receptor antibody-positive patients, efgartigimod is now being evaluated in the ongoing ALKIVIA trial.

This seamless Phase II/III study is investigating its potential across three myositis subsets - Immune-mediated Necrotizing Myopathy (IMNM), Antisynthetase Syndrome (ASyS), and dermatomyositis - with results expected in the second half of 2024.

SAPHNELO (Anifrolumab): AstraZeneca

SAPHNELO (anifrolumab) is a fully human monoclonal antibody that targets subunit 1 of the Type I IFN receptor, effectively inhibiting the activity of Type I interferons. The drug has received orphan drug designation from the US FDA and is currently in Phase III development for the treatment of dermatomyositis.

Drug Class Insights

Idiopathic inflammatory myositis treatment primarily involves corticosteroids as the first-line therapy, often combined with immunosuppressants like methotrexate or azathioprine for patients who do not respond adequately. In cases of severe or resistant disease, intravenous immunoglobulin (IVIG) may be beneficial, and biologics such as rituximab are considered for refractory cases.

Emerging therapies include dazukibart (PF 06823859), efgartigimod, SAPHNELO (anifrolumab), brepocitinib, and HIZENTRA, among others.

Dazukibart (PF-06823859) is a humanized IgG1K monoclonal antibody that blocks Interferon beta 1 (IFNß1), a key mediator in autoimmune responses.

Efgartigimod works by targeting the neonatal FcRn receptor, preventing the recycling of IgG antibodies, which leads to a reduction in pathogenic IgG levels in autoimmune diseases. HIZENTRA delivers a broad range of IgG antibodies with potential immunomodulatory effects, helping neutralize pathogens and modulate immune responses, though its exact mechanism of action is unclear. Both aim to address autoimmune conditions like dermatomyositis by modulating IgG activity.

Continued in report…

Market Outlook

Idiopathic inflammatory myositis, though classified as a rare disease, has gained increasing recognition in recent years. This is largely due to improvements in diagnostic techniques, greater awareness among healthcare professionals, and a deeper understanding of the condition. The rising incidence could drive market growth by identifying more patients seeking treatment. Management of inflammatory myositis typically involves a combination of pharmacological therapies and supportive interventions, with the primary objectives being to reduce inflammation, manage symptoms, maintain muscle function, and prevent complications.

The treatment landscape for idiopathic inflammatory myositis has advanced with a multi-faceted approach, combining medications, physical therapy, and supportive care. High-dose corticosteroids, such as prednisone or ACTHAR GEL, are typically the first-line therapy to control inflammation and immune response. Immunosuppressive agents like methotrexate, azathioprine, and tacrolimus are frequently added to reduce long-term corticosteroid use.

In cases of inadequate response, biologics such as rituximab offer targeted immune suppression. Physical therapy remains essential for maintaining muscle strength and function, while supportive measures, including NSAIDs and sun protection, help manage symptoms. Intravenous Immunoglobulin (IVIG) therapy provides another treatment option, with OCTAGAM 10% approved in the US and Europe and VENOGLOBULIN-IH 5% available in Japan. For severe refractory cases, IV cyclophosphamide may be considered, though its use is limited due to potentially severe side effects. Treatment plans are tailored based on disease severity and individual response, aiming to balance efficacy with minimizing side effects.

There is a significant need for new treatments for idiopathic inflammatory myositis, as existing therapies often fall short of fully managing the condition. Innovative drug development could provide more effective options for patients. Several promising drugs are currently in the pipeline, including dazukibart (PF 06823859), efgartigimod, SAPHNELO (anifrolumab), brepocitinib, HIZENTRA, empasiprubart, ulviprubart (ABC008), daxdilimab, nipocalimab, GLPG3667, enpatoran (M5049), froniglutide (PF1801), and CABA-201, among others.

• The total market size of idiopathic inflammatory myositis in the 7MM was approximately USD 447.0 million in 2023 and is projected to increase during the forecast period (2024-2034).
• The market size for Idiopathic Inflammatory Myositis in the US was approximately USD 268.3 million in 2023 and is anticipated to increase due to the launch of emerging therapies.
• The total market size of EU4 and the UK was calculated to be approximately USD 161.0 million in 2023, which was nearly 36% of the total market revenue for the 7MM.
• Among EU4 and the UK, Germany accounted for the highest market with approximately USD 47.5 million in 2023, followed by France with approximately USD 38.1 million in the respective year, and Italy with nearly USD 32.6 million in 2023.
• In 2023, the total market size of idiopathic inflammatory myositis was approximately USD 17.7 million in Japan, which is anticipated to increase during the forecast period (2024-2034).
• As per the estimates, among the therapies currently in use, the immunoglobulins held the largest market share, generating approximately USD 270.3 million in revenue in 2023 across the 7MM.

Idiopathic Inflammatory Myositis Drugs Uptake

This section focuses on the uptake rate of potential drugs expected to be launched in the market during 2020-2034.

Idiopathic Inflammatory Myositis Pipeline Development Activities

The report provides insights into different therapeutic candidates in Phase III, Phase II, and Phase I. It also analyzes key players involved in developing targeted therapeutics.

Pipeline development activities

The report covers information on collaborations, acquisitions and mergers, licensing, and patent details for emerging therapies for idiopathic inflammatory myositis.

KOL Views

To keep up with current market trends, we take KOLs and SMEs’ opinions working in the domain through primary research to fill the data gaps and validate our secondary research. Industry Experts contacted for insights on idiopathic inflammatory myositis evolving treatment landscape, patient reliance on conventional therapies, patient therapy switching acceptability, and drug uptake, along with challenges related to accessibility, including Medical/scientific writers, Medical Professionals, Professors, Directors, and Others.

The analysts connected with 50+ KOLs to gather insights; however, interviews were conducted with 15+ KOLs in the 7MM. Centers like the David Geffen School of Medicine, the US, University Hospital Aachen, Germany, Institute of Molecular Medicine, Brescia, Italy, National Institute of Allergy and Infectious Disease, Spain, Salford Royal NHS Foundation Trust, Manchester Academic Health Science Centre, UK, and Jikei University School of Medicine, Japan, among others, were contacted. Their opinion helps understand and validate current and emerging therapy treatment patterns or idiopathic inflammatory myositis market trends. This will support the clients in potential upcoming novel treatments by identifying the overall scenario of the market and the unmet needs.

Physician’s View

As per the KOLs from the US, assessing disease activity in inflammatory myositis is challenging due to the absence of validated biomarkers or objective measures. Reliable biomarkers, advanced imaging, and functional assessment tools would improve treatment decision-making and provide more accurate monitoring of treatment efficacy.

As per the KOLs from Germany, dermatomyositis and polymyositis share lymphocytic inflammation, but differ in lymphocyte involvement and distribution. Polymyositis features CD8+ T-cells attacking muscle fibers, leading to diffuse endomysial inflammation, without vasculopathy. In dermatomyositis, B cells and complement target small blood vessels, causing perivascular inflammation, muscle microinfarction, and perifascicular atrophy.

As per the KOLs from Japan, in biologic agents like rituximab are considered for refractory or severe cases of myositis, targeting specific immune cells involved in the disease in Japan. When myositis is linked to certain autoantibodies, Intravenous Immunoglobulin (IVIG) is administered to help regulate the immune response.

Qualitative Analysis

We perform Qualitative and market Intelligence analysis using various approaches, such as SWOT and Conjoint Analysis. In the SWOT analysis, strengths, weaknesses, opportunities, and threats in terms of disease diagnosis, patient awareness, patient burden, competitive landscape, cost-effectiveness, and geographical accessibility of therapies are provided. These pointers are based on the Analyst’s discretion and assessment of the patient burden, cost analysis, and existing and evolving treatment landscape.

Conjoint Analysis analyzes multiple emerging therapies based on relevant attributes such as safety, efficacy, frequency of administration, route of administration, and order of entry. Scoring is given based on these parameters to analyze the effectiveness of therapy.

To analyze the effectiveness of these therapies, have calculated their attributed analysis by giving them scores based on their ability to improve atrial and ventricular dimension/function and ability to regulate heart rate.

Further, the therapies’ safety is evaluated wherein the adverse events are majorly observed, and it sets a clear understanding of the side effects posed by the drug in the trials, which directly affects the safety of the molecule in the upcoming trials. It sets a clear understanding of the side effects posed by the drug in the trials. In addition, the scoring is also based on the route of administration, order of entry and designation, probability of success, and the addressable patient pool for each therapy. According to these parameters, the final weightage score and the ranking of the emerging therapies are decided.

Market Access and Reimbursement

Pfizer OCTAGAM Copay Program

Pfizer’s OCTAGAM Copay Program offers eligible patients with commercial insurance the opportunity to pay as little as USD 0 for OCTAGAM 10%. The program, available through specialty infusion pharmacies, provides a maximum benefit of USD 12,500 per calendar year or the cost of the patient’s copay over 12 months, whichever is less. Patients enrolled in state or federally-funded insurance programs are not eligible.


The report provides detailed insights on the country-wise accessibility and reimbursement scenarios, cost-effectiveness scenarios, programs making accessibility easier and out-of-pocket costs more affordable, insights on patients insured under federal or state government prescription drug programs, etc.

Scope of the Report

• The report covers a segment of key events, an executive summary, and a descriptive overview of idiopathic inflammatory myositis, explaining its causes, signs and symptoms, pathogenesis, and currently available therapies.
• Comprehensive insight into the epidemiology segments and forecasts, the future growth potential of diagnosis rate, disease progression, and treatment guidelines have been provided.
• Additionally, an all-inclusive account of the current and emerging therapies and the elaborative profiles of late-stage and prominent therapies will impact the current treatment landscape.
• A detailed review of the idiopathic inflammatory myositis market, historical and forecasted market size, market share by therapies, detailed assumptions, and rationale behind our approach is included in the report, covering the 7MM drug outreach.
• The report provides an edge while developing business strategies by understanding trends through SWOT analysis and expert insights/KOL views, patient journey, and treatment preferences that help shape and drive the 7MM idiopathic inflammatory myositis market.

Idiopathic inflammatory myositis report insights

• Patient Population
• Therapeutic Approaches
• Idiopathic Inflammatory Myositis Pipeline Analysis
• Idiopathic Inflammatory Myositis Market Size and Trends
• Existing and Future Market Opportunity

Idiopathic Inflammatory Myositis report key strengths

• 11 years Forecast
• The 7MM Coverage
• Idiopathic Inflammatory Myositis Epidemiology Segmentation
• Key Cross Competition
• Attribute analysis
• Drugs Uptake and Key Market Forecast Assumptions

Idiopathic Inflammatory Myositis report assessment

• Current Treatment Practices
• Unmet Needs
• Pipeline Product Profiles
• Market Attractiveness
• Qualitative Analysis (SWOT and Attribute Analysis)

Key Questions

Market Insights

• What was the total market size of idiopathic inflammatory myositis, the market size of idiopathic inflammatory myositis by therapies, and market share (%) distribution in 2020, and what would it look like by 2034? What are the contributing factors for this growth?
• How will Dazukibart (PF-06823859) affect the treatment paradigm of idiopathic inflammatory myositis?
• How will OCTAGAM 10% compete with other upcoming products and marketed therapies?
• Which drug is going to be the largest contributor by 2034?
• What are the pricing variations among different geographies for approved and marketed therapies?
• How would future opportunities affect the market dynamics and subsequent analysis of the associated trends?

Epidemiology Insights

• What are the disease risks, burdens, and unmet needs of idiopathic inflammatory myositis? What will be the growth opportunities across the 7MM with respect to the patient population pertaining to Idiopathic Inflammatory Myositis?
• What is the historical and forecasted idiopathic inflammatory myositis patient pool in the United States, EU4 (Germany, France, Italy, and Spain) and the United Kingdom, and Japan?
• Out of the countries mentioned above, which country would have the highest diagnosed prevalent idiopathic inflammatory myositis population during the forecast period (2024-2034)?
• What factors are contributing to the growth of idiopathic inflammatory myositis cases?

Current Treatment Scenario, Marketed Drugs, and Emerging Therapies

• What are the current options for the treatment of idiopathic inflammatory myositis? What are the current clinical and treatment guidelines for treating idiopathic inflammatory myositis?
• How many companies are developing therapies for the treatment of idiopathic inflammatory myositis?
• How many emerging therapies are in the mid-stage and late stage of development for treating idiopathic inflammatory myositis?
• What are the recent novel therapies, targets, mechanisms of action, and technologies developed to overcome the limitations of existing therapies?
• What is the cost burden of current treatment on the patient?
• Patient acceptability in terms of preferred treatment options as per real-world scenarios?
• What are the accessibility issues of approved therapy in the US?
• What is the 7MM historical and forecasted market of idiopathic inflammatory myositis?

Reasons to Buy

• The report will help develop business strategies by understanding the latest trends and changing treatment dynamics driving the idiopathic inflammatory myositis market.
• Insights on patient burden/disease prevalence, evolution in diagnosis, and factors contributing to the change in the epidemiology of the disease during the forecast years.
• Understand the existing market opportunities in varying geographies and the growth potential over the coming years.
• The distribution of historical and current patient share is based on real-world prescription data in the US, EU4 (Germany, France, Italy, and Spain) and the United Kingdom, and Japan.
• Identifying upcoming solid players in the market will help devise strategies to help get ahead of competitors.
• Detailed analysis and ranking of class-wise potential current and emerging therapies under the conjoint analysis section to provide visibility around leading classes.
• Highlights of Access and Reimbursement policies for idiopathic inflammatory myositis, barriers to accessibility of approved therapy, and patient assistance programs.
• To understand Key Opinion Leaders’ perspectives around the accessibility, acceptability, and compliance-related challenges of existing treatment to overcome barriers in the future.
• Detailed insights on the unmet needs of the existing market so that the upcoming players can strengthen their development and launch strategy.