Waldenström macroglobulinemia: biology, genetics, and therapy

Expanding CXCR4 variant landscape in WHIM syndrome: integrating clinical and functional data for variant interpretation

Warts, Hypogammaglobulinemia, Infections, Myelokathexis (WHIM) syndrome is a rare, combined immunodeficiency disease predominantly caused by gain-of-function variants in the CXCR4 gene that typically results in truncation of the carboxyl terminus of C-X-C chemokine receptor type 4 (CXCR4) leading to impaired leukocyte egress from bone marrow to peripheral blood. Diagnosis of WHIM syndrome continues to be challenging and is often made through clinical observations and/or genetic testing. Detection of a pathogenic CXCR4 variant in an affected individual supports the diagnosis of WHIM syndrome but relies on an appropriate annotation of disease-causing variants. Understanding the genotypic-phenotypic associations in WHIM syndrome has the potential to improve time to diagnosis and guide appropriate clinical management, resulting in a true example of precision medicine. This article provides an overview of the spectrum of CXCR4 variants in WHIM syndrome and summarizes the various lines of clinical and functional evidence that can support interpretation of newly identified variants.

HPV+ Oropharyngeal Cancer in Waldenström Macroglobulinemia

We present a case of squamous cell carcinoma (SCC) in the setting of Waldenström macroglobulinemia (WM). A 68-year-old male and daily marijuana smoker with recently diagnosed WM presented via telemedicine in 2020 for a progressively worsening sore throat and unintentional weight loss. Immunotherapy for WM was delayed due to the COVID-19 pandemic. In the clinic, examination revealed an indurated, tender midline mass at the base of the tongue, not limiting tongue mobility. The left level-II and right level-III lymph nodes were enlarged. The oropharyngeal lesion was biopsied, and pathology was consistent with human papillomavirus-positive (HPV+) SCC. Four cycles of concurrent chemotherapy and radiation for SCC were administered without delay, with an initial response. However, on surveillance, metastases to the brain and lungs were detected, and the patient was placed on palliative treatment as he did not meet eligibility for a clinical trial due to his WM. Concurrent WM and HPV+ SCC may have a worse prognosis, due to disease progression and reduced therapeutic options.

Pharmacokinetics-Pharmacodynamics Modeling and Evaluation of Tumor Response to Bortezomib Proteasome Inhibitor in Waldenstrom Macroglobulinemia

BACKGROUND

Waldenstrom's macroglobulinemia (WM), also known as lymphoplasmacytic lymphoma, is a type of non-Hodgkin's lymphoma in which the malignant cells produce many macroglobulin proteins. It originates from B cells and develops in the bone marrow, where Wm cells combine to produce distinct types of blood cells, resulting in reduced volumes of red blood cells, white blood cells, and platelets, making it harder for the body to fight diseases. Chemoimmunotherapy is being used for the clinical management of WM, but new targeted agents, the BTK inhibitor ibrutinib and the proteasome inhibitor bortezomib, have shown significant improvements in patients with relapsed/refractory WM. However, given its effectiveness, drug resistance and relapse are normal, and there is little research on the pathways responsible for drug effects on the tumor.

METHODS

In this study, Pharmacokinetics-pharmacodynamic simulations were done to assess the effect of the proteasome inhibitor bortezomib on the tumor. For this purpose, the Pharmacokinetics-pharmacodynamic model was developed. The model parameters were determined and calculated using the Ordinary Differential Equation solver toolbox and the least-squares function. Pharmacokinetic profiles and pharmacodynamic analysis were performed to determine the change in tumor weight associated with the use of proteasome inhibitors.

RESULTS

Bortezomib and ixazomib have been found to reduce tumor weight briefly, but once the dose is reduced, the tumor begins to grow again. Carfilzomib and oprozomib had better results, and rituximab reduced tumor weight more effectively.

CONCLUSION

Once validated, it is proposed that a combination of selected drugs can be evaluated in the laboratory to treat WM.

Identification of a Candidate Gene Set Signature for the Risk of Progression in IgM MGUS to Smoldering/Symptomatic Waldenström Macroglobulinemia (WM) by a Comparative Transcriptome Analysis of B Cells and Plasma Cells

Waldenström Macroglobulinemia (WM) is a B-cell lymphoma characterized by the precursor condition IgM monoclonal gammopathies of undetermined significance (IgM MGUS). We performed a gene expression profiling study to compare the transcriptome signatures of bone marrow (BM) B-cells and plasma cells of 36 WM patients, 13 IgM MGUS cases, and 7 healthy subjects used as controls (CTRLs) by Affymetrix microarray. We determined 2038 differentially expressed genes (DEGs) in CD19+ cells and 29 DEGs genes in CD138+ cells, respectively. The DEGs identified in B-cells were associated with KEGG pathways, mainly involved in hematopoietic cell lineage antigens, cell adhesion/focal adhesion/transmembrane proteins, adherens junctions, Wnt-signaling pathway, BCR-signaling pathway, calcium signaling pathway, complement/coagulation cascade, platelet activation, cytokine-cytokine receptor interactions, and signaling pathways responsible for cell cycle, apoptosis, proliferation and survival. In conclusion, we showed the deregulation of groups of genes belonging to KEGG pathways in the comparison among WM vs. IgM MGUS vs. CTRLs in B-cells. Interestingly, a small set of genes in B-cells displayed a common transcriptome expression profile between WM and IgM MGUS compared to CTRLs, suggesting its possible role in the risk of transformation of IgM MGUS to WM.

Histologic Transformation in an Untreated Waldenstrom's Macroglobulinemia After 14 Years: Case Report and Review of the Literature

Waldenstrom's macroglobulinemia (WM) is an indolent B-cell non-Hodgkin lymphoma characterized by lymphoplasmacytic histology in the bone marrow with monoclonal IgM. Median survival can be in excess of 10 years. The 5-year cumulative incidence of death is low at about 10%. One-third of all-cause specific mortality is due to the lymphoma for which histologic transformation (HT) is rare. Here we present a case of a 60-year-old man with longstanding untreated WM, presenting with minimally symptomatic transformation to diffuse large B-cell lymphoma (DLBCL), with an accompanying review of the literature. Transformed WM, diagnosed greater than 5 years, has a reported survival period of 8 - 9 months. This case highlights that after a decade of continued stability in WM, not requiring treatment, an acute change in laboratory data with minimally progressive IgM levels, in the absence of B symptoms and clinical findings, may be the harbinger of transformation and at the time of diagnosis can have a rapidly deteriorating clinical course. In this case, the tripling of the lactate dehydrogenase (LDH) as the primary drastic change demonstrates the importance of the rapid increase in LDH as a singly reliable marker for HT. Late transformation has been borne out as a negative variable as the generally indolent course of WM is curtailed with the poor outcome in HT. Although MYD88 wildtype is a possible predictive factor for transformation, it is unclear if late transformation is clonally or non-clonally related and further molecular investigation is needed.