Contemporary management of nodal and primary splenic marginal zone lymphoma.

Introduction: Marginal zone lymphoma (MZL) accounts for approximately 10% of all cases of non-Hodgkin lymphoma and includes 3 clinically distinct subtypes: extranodal (MALT), splenic (SMZL), and nodal (NMZL). Though commonly grouped in trials of iNHL the clinical behavior, molecular features, and response to therapy of MZL is distinct from other iNHL subtypes and varies among MZL subtypes.Areas covered: This review focuses on the contemporary management of NMZL and SMZL. Treatment with monoclonal antibodies, chemoimmunotherapy, BTK inhibitors, PI3K/mTOR inhibitors, Bcl2 inhibitors, lenalidomide, and CAR-T cell therapy will be covered.Expert opinion: In the era of targeted medicine, the need to develop MZL specific clinicogenetic models with prognostic and predictive value in both the frontline and relapsed/refractory setting is becoming increasingly apparent. Due to the relative rarity of each MZL subtype, the use of novel trial design with correlative studies is imperative to advance the field.

Should rituximab replace splenectomy in the management of splenic marginal zone lymphoma?

BACKGROUND: SMZL is a relatively rare low grade B-cell lymphoma, characterized usually by an indolent clinical behavior. Since there is no prospective randomized trials to establish the best treatment approach, decision on therapeutic management should be based on the available retrospective series. Based on these data, rituximab and splenectomy appear to be the most effective. Splenectomy represented the standard treatment modality until early 2000s. More than 90% of the patients present quick amelioration of splenomegaly related symptoms along with improvement of cytopenias related to hypersplenism. The median progression free survival was 8.25 years in the largest series of patients published so far, while the median 5- and 10- year OS were 84% and 67%, respectively. Responses to splenectomy are not complete since extrasplenic disease persists. Patients with heavy bone marrow infiltration, lymphadenopathy or other disease localization besides the spleen are not good candidates for splenectomy. Furthermore splenectomy is a major surgical procedure accompanied by acute perioperative complications as well as late toxicities mainly due to infections. For that reasons splenectomy is not appropriate for elderly patients or patients with comorbidities with a high surgical risk. On the other hand rituximab monotherapy displays high efficacy with minimal toxicity. Several published series have shown an ORR more than 90%, with high CR rates (∼50%). The 10-year PFS and OS were 63% and 85%, respectively in a series of 104 SMZL patients. The role of rituximab maintenance has been investigated by only one group. Based on these data, maintenance with rituximab further improved the quality of responses by increasing significantly the CR rates (from 42% at the end of induction to 71% at the end of maintenance treatment), as well as the duration of responses: 7-year PFS was 75% for those patients who received maintenance vs 39% for those who did not (p < 0.0004). However no difference in OS has been noticed between the two groups, so far. Summarizing the above data, it is obvious that Rituximab monotherapy is associated with high response rates, long response duration and favorable safety profile, rendering it as the treatment of choice in SMZL.

Mucosa-associated lymphoid tissue lymphoma with unusual 18F-FDG hypermetabolism arising at the colorectal anastomosis.

Mucosa-associated lymphoid tissue (MALT) lymphoma usually originates from the stomach and presents with low 18F-fluorodeoxyglucose (FDG) avidity with average maximum standard uptake value of 3.6. Colorectal MALT lymphoma is a rare entity that contributes to 1.6% of all MALT lymphomas and < 0.2% of large intestinal malignancies. The case reported herein firstly revealed stage IIE MALT lymphoma with unexpected higher 18F-FDG avidity of 18.9 arising at the colorectal anastomosis in a patient with a surgical history for sigmoid adenocarcinoma, which was strongly suspected as local recurrence before histopathological and immunohistochemical examinations. After accurate diagnosis, the patient received four cycles of standard R-CVP regimen (rituximab, cyclophosphamide, vincristine and prednisone), combined target therapy and chemotherapy, instead of radiotherapy recommended by National Comprehensive Cancer Network guidelines. He tolerated the treatment well and reached complete remission.

Genetic polymorphisms and tissue expression of interleukin-22 associated with risk and therapeutic response of gastric mucosa-associated lymphoid tissue lymphoma.

Chronic Helicobacter pylori-stimulated immune reactions determine the pathogenesis of gastric mucosa-associated lymphoid tissue (MALT) lymphoma. We aimed to explore the genetic predisposition to this lymphoma and its clinical implication. A total of 68 patients and 140 unrelated controls were genotyped for 84 single-nucleotide polymorphisms in genes encoding cytokines, chemokines and related receptors that play important roles in T cell-mediated gastrointestinal immunity. Five genotypes in IL-22, namely CC at rs1179246, CC at rs2227485, AA at rs4913428, AA at rs1026788 and TT at rs7314777, were associated with disease susceptibility. The former four genotypes resided in the same linkage disequilibrium block (r(2)=0.99) that conferred an approximately threefold higher risk. In vitro experiments demonstrated that co-culturing peripheral mononuclear cells or CD4(+) T cells with H. pylori stimulated the secretion of interleukin-22 (IL-22), and that IL-22 induced the expression of antimicrobial proteins, RegIIIα and lipocalin-2, in gastric epithelial cells. Furthermore, patients with gastric tissue expressing IL-22 were more likely to respond to H. pylori eradication (14/22 vs 4/19, P<0.006). We conclude that susceptibility of gastric MALT lymphoma is influenced by genetic polymorphisms in IL-22, the product of which is involved in mucosal immunity against H. pylori and associated with tumor response to H. pylori eradication.

Protease activity of the API2-MALT1 fusion oncoprotein in MALT lymphoma development and treatment.

Gastric mucosa-associated lymphoid tissue (MALT) lymphoma is a prototypical cancer that occurs in the setting of chronic inflammation and an important model for understanding how deregulated NF-κB transcriptional activity contributes to malignancy. Most gastric MALT lymphomas require ongoing antigenic stimulation for continued tumor growth, and Stage I disease is usually cured by eradicating the causative microorganism, Helicobacter pylori, with antibiotics. However, in a subset of MALT lymphomas, chromosomal translocations are acquired that render the lymphoma antigen-independent. The recurrent translocation t(11;18)(q21;q21) is associated with failure to respond to antibiotic therapy and increased rate of dissemination. This translocation creates the API2-MALT1 fusion oncoprotein, which comprises the amino terminus of inhibitor of apoptosis 2 (API2 or cIAP2) fused to the carboxy terminus of MALT1. A common characteristic of chromosomal translocations in MALT lymphoma, including t(11;18), is that genes involved in the regulation of the NF-κB transcription factor are targeted by the translocations, and these genetic perturbations thereby result in deregulated, constitutive NF-κB stimulation. In the last decade, great insights into the roles of API2 and MALT1 in NF-κB signaling have been made. For example, recent pivotal studies have uncovered the long sought-after proteolytic activity of MALT1 and have demonstrated its critical involvement in the survival of certain lymphomas. Here, we review the current understanding of the role of MALT1 in normal lymphocyte function and lymphomagenesis. We then highlight our recent work that has revealed an intriguing link between the proteolytic activity of the API2-MALT1 fusion and its ability to influence lymphomagenesis by cleaving a key NF-κB regulatory protein, NF-κB-inducing kinase.

Clinical features and prognosis of gastric MALT lymphoma with special reference to responsiveness to H. pylori eradication and API2-MALT1 status.

BACKGROUND AND AIM: Clinicopathologic characteristics and prognosis of Helicobacter pylori eradication-resistant gastric MALT lymphoma have not been well clarified. We analyzed a consecutive series of gastric MALT lymphomas at our institution regarding treatment, clinical course, and prognosis, with special reference to responsiveness to H. pylori eradication and presence of API2-MALT1. METHODS: Subjects were 92 consecutive patients with gastric MALT lymphoma. Seventy were H. pylori positive, and 87 received H. pylori eradication therapy. The remaining five cases were API2-MALT1 positive and did not receive eradication treatment. Second-line treatments were radiation therapy, total gastrectomy, and chemotherapy (rituximab, rituximab plus CHOP, or rituximab plus 2-chlorodeoxyadenosine). RESULTS: Gastric MALT lymphoma was classified into three groups, except one case with API2-MALT1 who responded to H. pylori eradication therapy: responders without API2-MALT1 (group A, N = 56, 65%), nonresponders without API2-MALT1 (group B, N = 16, 19%), and nonresponders with API2-MALT1 (group C, N = 14, 16%). Most cases in group A attained complete remission (CR) in 2 or 3 months and CR persisted for an average of 51.1 months (3-134 months). Recurrence was only seen in one case. In groups B and C, radiation therapy, chemotherapy, and total gastrectomy resulted in CR in 13, 5, and 2 cases, respectively. In 5 group B patients and 6 group C patients who did not undergo second-line therapy, disease did not progress for an average of 10.4 and 40.1 months, respectively. In 1 group C case who did not receive second-line treatment, lymphoma metastasized to the lung 12 yr after eradication. All group B patients and all but 2 group C patients remain alive; one of these deaths was from gastric carcinoma developing 7 yr after eradication. CONCLUSION: Gastric MALT lymphoma responding to H. pylori eradication demonstrated good prognosis, and for nonresponsive cases, second-line treatments resulted in CR. However, careful observation for development of gastric carcinoma and disease progression is essential during follow-up of API2-MALT1-positive MALT lymphoma when patients decline second-line treatment.