Waldenström's macroglobulinemia - clinical symptoms and review of therapy yesterday, today and tomorrow.

Background: Waldenström macroglobulinemia (WM) is a lymphoplasmocytic lymphoma with immunoglobulin M monoclonal protein. The incidence of this disease is very low (0.4/100,000), so that this disease can be regarded as an orphan's disease. It means that new drugs are often tested and registered for more frequent diseases.

Purpose: In this review we will focus on the efficacy of the new drugs for WM.

Results: The current treatment options for symptomatic WM patients include alkylating agent cyclophosphamide and anti-CD20 monoclonal antibodies. Therapy with rituximab and bendamustin resulted in longer therapeutic response then therapy with rituximab, cyclophosphamide and dexamethasone. Many drugs, used in multiple myeloma (MM), shoved promising results in WM patients. Bortezomib is effective in WM, but its neurotoxicity is higher in WM than in MM patients. Therefore, new proteasome inhibitors, carfilzomib and ixazomib, are better tolerated as documented in several studies. New types of antiCD20 antibody (obinutuzumab) can be used in patients with rituximab intolerance. in five of our patients with WM, obinutuzumab and bendamustin reached deeper responses than therapies administered in previous lines of therapy. Oral Bruton tyrosine kinase (BTK) inhibitor ibrutinib alone and in combination with rituximab have extended the treatment options for WM patients. New BTK inhibitors (e. g. acalabrutinib, zanubrutinib, and vecabrutinib) were tested and their lower toxicity (atrial fibrillation) was documented. Moreover, the BCL2 inhibitor venetoclax is newly tested.

Conclusion: New antiCD20 antibody (obinutuzumab) is of advantage in patients with WM with rituximab intolerance as well as bendamustin and new proteasome inhibitors (ixazomib and carfilzomib) or new BTK inhibitors with lower cardiotoxicity. Many of the abovementioned drugs do not have official registration for WM and can be administrated with the consent of the health care provider only. Thus, this work brings evidence of their efficacy.