Successful treatment with tirabrutinib for relapsed lymphoplasmacytic lymphoma complicated by Bing-Neel syndrome

How I use genomics and BTK inhibitors in the treatment of Waldenström macroglobulinemia

ABSTRACT

Mutations in MYD88 (95%-97%) and CXCR4 (30%-40%) are common in Waldenström macroglobulinemia (WM). TP53 is altered in 20% to 30% of patients with WM, particularly those previously treated. Mutated MYD88 activates hematopoietic cell kinase that drives Bruton tyrosine kinase (BTK) prosurvival signaling. Both nonsense and frameshift CXCR4 mutations occur in WM. Nonsense variants show greater resistance to BTK inhibitors. Covalent BTK inhibitors (cBTKi) produce major responses in 70% to 80% of patients with WM. MYD88 and CXCR4 mutation status can affect time to major response, depth of response, and/or progression-free survival (PFS) in patients with WM treated with cBTKi. The cBTKi zanubrutinib shows greater response activity and/or improved PFS in patients with WM with wild-type MYD88, mutated CXCR4, or altered TP53. Risks for adverse events, including atrial fibrillation, bleeding diathesis, and neutropenia can differ based on which BTKi is used in WM. Intolerance is also common with cBTKi, and dose reduction or switchover to another cBTKi can be considered. For patients with acquired resistance to cBTKis, newer options include pirtobrutinib or venetoclax. Combinations of BTKis with chemoimmunotherapy, CXCR4, and BCL2 antagonists are discussed. Algorithms for positioning BTKis in treatment naïve or previously treated patients with WM, based on genomics, disease characteristics, and comorbidities, are presented.

Waldenström Macroglobulinemia-Associated Peripheral Neuropathy in the Brachial Plexus With Bing-Neel Syndrome Diagnosed Through Repeated Cerebrospinal Tests

In Waldenström macroglobulinemia (WM), confirming the presence of Bing-Neel syndrome (BNS) is important because drugs that penetrate the central nervous system (CNS) must be selected. We report the case of a 75-year-old man for whom tirabrutinib, a second-generation Bruton's tyrosine kinase inhibitor (BTKi), was useful in treating WM-associated peripheral neuropathy (PN) with BNS. Numbness and muscle weakness in the fingers occurred three years after the initial treatment of WM. WM-associated PN due to demyelinating disease was diagnosed based on the results of a nerve conduction study and magnetic resonance imaging showing bilateral symmetric swelling of the brachial plexus. The cerebrospinal fluid (CSF) cytology results were initially negative; however, the CSF test was repeated because of extremely high protein levels (984 mg/dL) and slightly elevated leukocyte counts (14/µL). The second test revealed abnormal lymphoplasmacytic cells (189/µL), indicating BNS. Rituximab and high-dose methotrexate-containing chemotherapy were administered. Despite the subsequent negative CSF cytology results, his neurological symptoms persisted but subsided soon after the initiation of tirabrutinib. The therapeutic effects of tirabrutinib persisted for 25 months. This case suggested that a careful search for concurrent BNS is important when lesions are close to the CNS or when atypical CSF findings are obtained in patients with WM-associated PN, especially when BTKi options are available.

Waldenström macroglobulinemia: 2023 update on diagnosis, risk stratification, and management

DISEASE OVERVIEW

Waldenström macroglobulinemia (WM) is a lymphoplasmacytic lymphoma with immunoglobulin M (IgM) monoclonal protein. Clinical features include anemia, thrombocytopenia, hepatosplenomegaly, lymphadenopathy, and rarely hyperviscosity.

DIAGNOSIS

Presence of IgM monoclonal protein associated with ≥10% clonal lymphoplasmacytic cells in bone marrow confirms the diagnosis. The L265P mutation in MYD88 is detectable in more than 90% of patients and is found in most IgM MGUS patients. MYD88 is not required for the diagnosis.

RISK STRATIFICATION

Age, hemoglobin level, platelet count, β2 microglobulin, LDH, and monoclonal IgM concentrations are characteristics that are predictive of outcomes.

RISK-ADAPTED THERAPY

Not all patients who fulfill WM criteria require therapy; these patients can be observed until symptoms develop. Rituximab-monotherapy is inferior to regimens that combine it with bendamustine, an alkylating agent, a proteosome inhibitor, or a BTK inhibitor. The preferred Mayo Clinic induction is either rituximab and bendamustine (without rituximab maintenance) or zanubrutinib.

MANAGEMENT OF REFRACTORY DISEASE

Bortezomib, cyclophosphamide, fludarabine, thalidomide, everolimus, Bruton Tyrosine Kinase inhibitors, carfilzomib, lenalidomide, bendamustine, and venetoclax have all been shown to have activity in relapsed WM. Given WM's natural history, the reduction of therapy toxicity is an important part of treatment selection.

Mixed Diffuse and Tumoral Form of Bing-Neel Syndrome Successfully Treated with Ibrutinib

Introduction

Bing-Neel syndrome (BNS) is a rare and heterogenous manifestation of Waldenström macroglobulinemia (WM) involving central nervous system (CNS) infiltration by malignant lymphoplasmacytic cells. Efforts to standardize diagnostic criteria have improved in recent years, as have treatment options including the use of the Bruton tyrosine kinase inhibitor (BTKI) ibrutinib.

Case Presentation

Here, we present the case of a 70-year-old male with a remote history of WM previously treated with bendamustine and rituximab, who presented to medical attention with several months of left-sided weakness, headache, and ataxia. Brain magnetic resonance imaging revealed numerous enhancing masses in the bilateral cerebral hemispheres, inferior medulla, and upper cervical spine. Laboratory studies showed serum IgM lambda monoclonal gammopathy and elevated free serum kappa and lambda light chains, while cerebrospinal fluid flow cytometry revealed CD19+ B cells. Stereotactic brain biopsy of a right frontal brain lesion was consistent with lymphoplasmacytic lymphoma, confirmed by a positive MYD88 L265P mutation. He received ibrutinib 420 mg orally daily, and this resulted in appreciable clinical and radiologic responses, which have persisted over a 31-month period.

Conclusion

The advent of molecularly targeted agents and novel therapies for WM has provided patients and clinicians with additional therapeutic options. The use of BTK inhibitors with their high-level CNS penetrance, in particular, offers a novel way to treat BNS and improve patient overall survival while maintaining a high level of quality of life. We discuss the importance of MYD88 L265P testing in the context of BNS as well as the expanding role of BTKIs in treating this disease.

Bing-Neel Syndrome Successfully Treated with Tirabrutinib

Bing-Neel syndrome (BNS) is a rare central nervous system manifestation of lymphoplasmacytic lymphoma/Waldenström macroglobulinemia (LPL/WM). We herein report a 62-year-old man with LPL/WM after multiple chemotherapies. He had weakness of lower extremities and elevated serum IgM levels. A bone marrow examination showed lymphoplasmacytic cells infiltration. Contrast-enhanced magnetic resonance imaging suggested enhancing lesions in the cauda equina roots. He was diagnosed with BNS and started on treatment with tirabrutinib 480 mg daily. Within three months, he showed clinical and radiologic improvement. Tirabrutinib may have utility as an effective treatment for BNS.

Successful treatment with tirabrutinib for relapsed Bing-Neel syndrome following high-dose methotrexate and craniospinal irradiation

A 63-year-old man was diagnosed with Waldenström's macroglobulinemia (WM). Six courses of R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone) resulted in complete remission, but WM relapsed three years after R-CHOP. After six courses of BR (bendamustine, rituximab), the serum IgM level and CRP normalized. Four years after BR, the patient presented with muscle weakness, sensory disturbance, and myoclonus of lower limbs. T2-weighted magnetic resonance imaging (MRI) showed areas of signal hyperintensity with contrast enhancement in the right temporal and parietal lobes in brain parenchyma, medulla, bilateral basal ganglia, white matter of occipital lobe, and thoracic spinal cord at the Th2-11 levels. Open brain biopsy revealed diffuse proliferation of small lymphocytes and plasmacytoid lymphocytes on the brain surface and around cerebral blood vessels, resulting in a diagnosis of Bing-Neel syndrome (BNS). Two courses of R-MPV (rituximab, methotrexate, procarbazine, and vincristine) resulted in progressive disease, but the neurological symptoms and MRI findings improved following craniospinal irradiation of 30.6 Gy. Three years after craniospinal irradiation, T2-weighted MRI showed recurrence of BNS with progression of myoclonus of lower limbs and IgM elevation. Tirabrutinib was started for the second recurrence of WM and progression of BNS. Two months after the initiation of treatment with tirabrutinib, the myoclonus of lower limbs disappeared and the MRI findings showed improvement. Serum IgM levels decreased and no adverse events were observed. Tirabrutinib shows promise as a therapeutic option for relapsed BNS.

The Use of Bruton Tyrosine Kinase Inhibitors in Waldenström’s Macroglobulinemia

The use of Bruton Tyrosine Kinase (BTK) inhibitors in Waldenström’s Macroglobulinemia (WM) is evolving. Ibrutinib, a first-generation BTK inhibitor, is currently approved for use in frontline and relapsed/refractory disease. Second-generation BTK inhibitors are being used and studied to improve clinical outcomes and/or safety profile. Zanubrutinib, one such second-generation inhibitor, was recently approved in treatment-naive and refractory/relapsed patients. Here, we review the use of BTK inhibitors in WM in front-line and refractory or relapsed settings. We also highlight common adverse events, the emergence of BTK inhibitors resistance, and future directions of their use.