Waldenström's macroglobulinemia (WM) is a rare subtype of non-Hodgkin lymphoma characterized by the malignant accumulation of IgM-producing lymphoplasmacytic cells in the bone marrow and other organs. Recurrent somatic mutations in MYD88 and CXCR4 give the malignant cells a survival advantage through an apoptosis escape mechanism (i.e., immortalization).
A third of patients are diagnosed with Waldenström's macroglobulinemia in an asymptomatic phase, also known as smoldering or inactive WM. These patients have an overall survival rate similar to age, sex, and race-match individuals of the general population. As WM is currently incurable using standard therapies and the available therapies can induce side effects, therapy should be reserved for symptomatic WM patients whose activities of daily living are impacted by the disease.
Approximately 80% of Waldenström's macroglobulinemia patients with asymptomatic WM will require therapy within ten years of diagnosis. Criteria for treating WM include symptomatic anemia, constitutional symptoms (e.g., fevers, drenching night sweats, or unintentional weight loss), symptomatic hyperviscosity, progressive neuropathy, and symptomatic lymphadenopathy or organomegaly. Other rare indications to treat include cryoglobulinemia, cold agglutinin syndrome, amyloidosis, or the rare Bing-Neel syndrome, in which WM cells invade the central nervous system.
Several treatment options exist for patients with symptomatic Waldenström's macroglobulinemia, but no large randomized studies have compared the more commonly used regimens. Therefore, treatment selection is highly personalized and should consider the patient's clinical presentation, comorbidities, concurrent medications, genomic profile, treatment objective, and personal preferences.
Chemoimmunotherapy regimens are commonly used with a long track record and evidence of durable responses. Proteasome inhibitors can also be used combined with rituximab. Over the last decade and based on research developed at the Bing Center for Waldenström's Macroglobulinemia, Bruton tyrosine kinase (BTK) inhibitors have become a standard treatment option, supported by the approval of ibrutinib (with or without rituximab) and zanubrutinib by the Food and Drug Administration to treat WM in recent years. Beyond chemoimmunotherapy and BTK inhibitors, BCL2 antagonists such as venetoclax and non-covalent BTK inhibitors such as pirtobrutinib are safe and effective options. Both agents were also developed at the Bing Center and are endorsed by the National Comprehensive Cancer Network guidelines.
The Bing Center at Dana-Farber is one of the largest basic, translational, and clinical research programs dedicated to Waldenström's macroglobulinemia under the direction of Steven Treon, MD, PhD. At the Bing Center, Jorge Castillo, MD, (Clinical Director), Shayna Sarosiek, MD, and Cat Flynn, NP, see approximately 3,000 patients with WM and IgM-related disorders annually. In addition to providing clinical care to WM patients from New England and nationwide, researchers at the Bing Center design and execute innovative clinical trials evaluating novel agents to improve the lives of patients with WM. The clinical research efforts include Andrew Branagan, MD, PhD, at Massachusetts General Hospital and Gottfried von Keudell, MD, at Beth Israel Deaconess Medical Center.
Current clinical trials at the Bing Center evaluate:
- Novel agents, such as the 2nd generation BCL2 inhibitor, sonrotoclax (NCT05952037), and the BTK degrader, BGB-16673 (NCT05006716).
- Novel combinations, such as pirtobrutinib and venetoclax (NCT05734495); zanubrutinib, bendamustine, and rituximab (NCT06561347); and zanubrutinib and sonrotoclax (NCT05952037).
- Immunotherapies, such as the anti-CD19 antibody-drug conjugate, loncastuximab tesirine (NCT05190705), and the anti-CD20 bispecific antibody epcoritamab (NCT06510491).
Given Waldenström's macroglobulinemia rarity, clinical trials are essential to advance the field, and multi-institutional collaboration is crucial. Dr. Castillo was granted funds by the International Waldenström's Macroglobulinemia Foundation to create and sustain a United States (US)-based think tank to advance clinical research in WM (WM-NET). The WM-NET comprises more than 20 academic institutions in the US (map) and will help design and support scientifically-driven multi-institutional clinical trials in the US, as well as develop an academic prospective database and a biorepository to enhance research efforts further. There is, indeed, work to be done.
Map of the participating members of the WM-NET
Read additional articles from Advances in Hematologic Malignancies - Winter 2025