What are the treatment options for Castleman disease?

Treatment of Castleman Disease

For HHV-8-associated multicentric Castleman disease (MCD), rituximab is the recommended first-line therapy, with etoposide or liposomal doxorubicin added in severe cases; for idiopathic MCD (iMCD), siltuximab is the treatment of choice; and for unicentric Castleman disease (UCD), complete surgical resection is curative. 1

Disease Classification and Treatment Strategy

Castleman disease requires subtype-specific management based on three key distinctions:

Unicentric Castleman Disease (UCD)

• Surgical excision is the definitive treatment and achieves cure in resectable cases 2, 3
• Complete resection eliminates recurrence risk 3
• If tumor size precludes immediate surgery, preoperative pharmacological treatment may downsize the lesion 2
• Radiotherapy has limited experience but may be considered when surgery is not feasible 2

HHV-8-Associated Multicentric Castleman Disease

First-line management:

• Rituximab monotherapy is the standard approach based on prospective studies showing rapid decline in HHV-8 viral load, IL-6, IL-10, and C-reactive protein 1
• Always optimize antiretroviral therapy (ART) in HIV-positive patients, even with undetectable viral loads 1

Severe cases require intensification:

• Add etoposide to rituximab to control cytokine storm consequences, particularly in hemophagocytic syndrome 1
• If Kaposi sarcoma coexists, combine rituximab with cytotoxic chemotherapy (etoposide or liposomal doxorubicin) 1
• Caution: Rituximab should be used carefully in patients with CD4 counts <50 cells/mL; consider delaying until after etoposide cycles, though rituximab improves outcomes and reduces lymphoma risk 1

Relapsed/refractory disease:

• Multiple rituximab-based rechallenge cycles are safe and effective 1
• More aggressive regimens (e.g., CHOP) for rituximab-refractory cases 1
• Antivirals, immunomodulators, and IL-6-blocking agents have limited value 1

Idiopathic Multicentric Castleman Disease (iMCD)

First-line therapy:

• Siltuximab (anti-IL-6 antibody) is the FDA-approved treatment of choice 2, 4, 5
• Response rates are <50% in unselected populations but higher when restricted to patients with markedly elevated inflammatory markers 2
• Tocilizumab (anti-IL-6 receptor antibody) is a suitable alternative when siltuximab is unavailable or ineffective 2, 6
• Corticosteroids often support initial therapy 4

Important subtype distinction within iMCD:

• iMCD-IPL (idiopathic plasmacytic lymphadenopathy): Generally responds well to IL-6 blockade 4
• iMCD-TAFRO (thrombocytopenia, anasarca, fever, reticulin fibrosis, organomegaly): Aggressive phenotype requiring early escalation to cyclosporine, rituximab, or chemotherapy 4, 5

Second/third-line options for inadequate siltuximab response:

• Rituximab combined with cytostatics (demonstrated efficacy in clinical studies) 2, 3
• R-CHOP chemotherapy shows favorable outcomes in resource-limited settings where anti-IL-6 antibodies are inaccessible 3
• Cyclophosphamide combined with thalidomide or bortezomib 2
• Sirolimus monotherapy (mTOR inhibitor, based on mTORC1 hyperactivation in iMCD) 2, 4
• Oral thalidomide-cyclophosphamide-dexamethasone (TCD) for refractory cases 3
• Case-level evidence supports: anakinra, ruxolitinib, lenalidomide 2

POEMS-Associated MCD

• Treatment targets the underlying monoclonal plasma cell disorder, which drives both MCD and POEMS syndrome 2
• Plasma cell-directed therapies (similar to myeloma treatment approaches) are indicated 4

Critical Management Considerations

Common pitfalls to avoid:

• Do not use siltuximab in HHV-8-associated MCD—rituximab is superior 1
• Recognize that rituximab can cause reactivation or progression of concomitant Kaposi sarcoma; add liposomal doxorubicin if this occurs 1
• NHL incidence remains high despite rituximab, especially HHV-8-associated lymphomas (primary effusion lymphoma, DLBCL); maintain surveillance every 3-6 months 1
• Splenectomy provides only short-term symptom resolution for severe refractory cytopenias 1

Monitoring requirements:

• Regular clinical, virological, and biochemical response assessment during acute episodes 1
• CT or FDG-PET-CT after completing immunochemotherapy 1
• Patients must understand relapse risk and seek immediate specialist attention if symptoms recur 1

Emerging considerations:

• JAK-2 inhibitors warrant investigation in relapsed/refractory settings 4
• Biomarker-driven treatment selection and early identification of IL-6-refractory disease will improve future outcomes 5
• The heterogeneous biology of CD explains variable treatment responses and necessitates subtype-specific approaches 2, 4