Comparison for ILD
In IIM-associated ILD, the medication “menu” is broadly shared, but the preferred sequence and intensity are driven by subclass/serology (especially antisynthetase vs anti-MDA5), ILD tempo (subacute/chronic vs rapidly progressive), and pattern/progression (inflammatory vs fibrosing).
Explanation
Medication classes used for IIM-ILD
| Glucocorticoids | Induction (often with a steroid-sparing agent immediately) | Most IIM-ILD; essential upfront in acute inflammatory ILD | Common standard; alone often insufficient in ASS-ILD and anti-MDA5 RP-ILD (expert consensus + cohort experience). |
| Mycophenolate mofetil (MMF) | First-line steroid-sparing for chronic/subacute ILD | ASS-ILD, classic DM/PM-ILD, overlap ILD | ACR SARD-ILD guideline conditionally recommends MMF as first-line. |
| Azathioprine (AZA) | Alternative first-line steroid-sparing | Similar to MMF (often if MMF not tolerated) | ACR SARD-ILD guideline conditionally recommends AZA as first-line. |
| Calcineurin inhibitors (tacrolimus/cyclosporine) | Steroid-sparing; often used when ILD is more aggressive or MMF insufficient | ASS-ILD; anti-MDA5 ILD (often part of combination) | Commonly used; recent US cohort data for tacrolimus as first-line in IIM-ILD; anti-MDA5 combo regimens usually include a CNI. |
| Cyclophosphamide (IV CYC) | Induction for severe/progressive ILD, especially when rapid decline | Severe IIM-ILD/overlap ILD; sometimes anti-MDA5 RP-ILD | RECITAL: RTX not superior to CYC, both improved FVC at 24 wks in CTD-ILD (included IIM). |
| Rituximab (RTX) | Escalation/rescue; alternative to CYC when IV therapy needed | Refractory/progressive ASS-ILD; severe CTD-ILD | Real-world ASS-ILD rescue benefit; RECITAL supports RTX as an alternative IV option (less AEs). |
| IVIG | Adjunct (esp. when infection risk limits cytotoxic agents; or concomitant active myositis/skin) | ASS-ILD adjunct; refractory disease | Retrospective AS-ILD series suggests stabilization/improvement in lung function + steroid sparing. |
| JAK inhibitors (tofacitinib, baricitinib, etc.) | Targeted escalation, especially in anti-MDA5 ILD (hyperinflammatory phenotype) | Anti-MDA5 DM-ILD (often rapidly progressive) | Data include NEJM correspondence/series and subsequent studies suggesting potential survival/response benefit; baricitinib data emerging. |
| Abatacept | Emerging option for ASS-ILD (selected cases/pilots) | ASS-ILD (pilot/real-world) | Retrospective and pilot RCT signals in ASS-ILD. |
| Antifibrotic (nintedanib) | Add-on for progressive fibrosing phenotypedespite immunosuppression | “Progressive fibrosing” ILD across CTDs (including myositis-related subsets) | INBUILD: slowed FVC decline in progressive fibrosing ILDs; autoimmune-related subgroup consistent. Myositis-specific MINT trial underway. |
ACR’s SARD-ILD guideline is helpful as an umbrella: it conditionally recommends MMF, AZA, RTX, CYC as first-line ILD treatment options in systemic autoimmune rheumatic diseases, which includes IIM in scope.
Subclass-driven “how we actually use them”
1) Antisynthetase syndrome ILD (ASS-ILD: anti-Jo-1, PL-7, PL-12, EJ, OJ, etc.)
Typical approach
- Steroids + MMF or AZA (first-line scaffold), with early steroid-sparing intent.
- Add/shift to a calcineurin inhibitor (tacrolimus/cyclosporine) if lung disease is more aggressive, relapsing, or not responding sufficiently.
- Rituximab for refractory/progressive ILD (common real-world “next step”).
- IVIG as adjunct in selected patients (steroid-sparing; concomitant myositis/skin; infection-risk tradeoffs).
- Nintedanib if the course becomes progressive fibrosing despite immunosuppression.
- Abatacept is emerging (not yet “standard,” but increasingly discussed).
Clinical rationale: ASS-ILD often behaves like a chronic inflammatory ILD with relapses; you want a durable steroid-sparing backbone (MMF/AZA ± CNI) and reserve RTX/CYC for escalation.
2) Anti-MDA5 dermatomyositis ILD (often clinically amyopathic; frequently rapidly progressive)
Typical approach
- Early aggressive combination therapy is common when the phenotype is rapidly progressive: high-dose glucocorticoids + CNI (tacrolimus/cyclosporine) + IV cyclophosphamide (“triple therapy”). A multicenter prospective study supports combined immunosuppression in this setting.
- Rescue adjuncts in refractory cases include plasma exchange/hemoperfusion/ECMO pathways (center- and severity-dependent).
- JAK inhibitors (tofacitinib, baricitinib) have become a major “escalation lane” in anti-MDA5 ILD, with multiple reports/series and ongoing debate about where they belong (frontline vs rescue).
- Important nuance: not all cohorts show clear superiority of “triple therapy” in all-comers; real-world data can be mixed, and infection risk is a major competing hazard.
Clinical rationale: anti-MDA5 RP-ILD can deteriorate faster than confirmatory tests; the treatment philosophy is front-loaded immunosuppression, then rapid reassessment, with a low threshold for rescue strategies—balanced against infection risk.
3) Classic DM/PM-ILD (non-MDA5, non-ASS serologies; NSIP/OP patterns common)
Typical approach
- Steroids + MMF or AZA as the usual first-line.
- Tacrolimus often used if response is incomplete or relapse occurs.
- Rituximab or cyclophosphamide for severe/progressive disease (RECITAL supports RTX as a reasonable alternative to CYC for patients needing IV induction).
- Nintedanib if it evolves into a progressive fibrosing phenotype.
4) Overlap myositis (e.g., with systemic sclerosis or MCTD features)
Here you often treat “as CTD-ILD,” using the same escalation logic:
- MMF/AZA ± RTX/CYC, with RECITAL being particularly relevant for IV induction choice.
5) IMNM-ILD (anti-SRP/anti-HMGCR)
ILD is less typical than in ASS or anti-MDA5 DM, so evidence is thinner; when ILD is present, clinicians generally borrow the same CTD-ILD framework (MMF/AZA/CNI → RTX/CYC; antifibrotic if progressive fibrosing), while also treating the dominant myopathy phenotype.
Result
If you want a clean comparison by subclass:
- ASS-ILD: MMF/AZA backbone early; CNIs commonly; RTX frequent for refractory; IVIG adjunct; nintedanib for progressive fibrosing behavior.
- Anti-MDA5 DM-ILD (RP-ILD): early combination induction (steroids + CNI + often IV CYC); JAK inhibitors increasingly used (frontline or rescue depending on center/phenotype); rescue adjuncts considered in failures.
- Classic DM/PM-ILD: start like ASS-ILD but typically less “hyperacute”; escalate to RTX/CYC when needed; add nintedanib if fibrosing progression.
- Overlap ILD: CTD-ILD paradigm; RECITAL directly supports RTX as an alternative to CYC for severe/progressive disease needing IV induction.