Expression of JL1 is an effective adjunctive marker of leukemia cutis

JL1 Antigen Expression on Bone Marrow Lymphoma Cells from Patients With Non-Hodgkin Lymphoma

Background

JL1, a CD43 epitope and mucin family cell surface glycoprotein, is expressed on leukemic cells. An anti-JL1 antibody combined with a toxic substance can have targeted therapeutic effects against JL1-positive leukemia; however, JL1 expression on bone marrow (BM) lymphoma cells has not been assessed using flow cytometry. We investigated JL1 expression on BM lymphoma cells from patients with non-Hodgkin lymphoma (NHL) to assess the potential of JL1 as a therapeutic target.

Methods

Patients with BM involvement of mature B-cell (N=44) or T- and natural killer (NK)-cell (N=4) lymphomas were enrolled from May 2015 to September 2016. JL1 expression on BM lymphoma cells was investigated using flow cytometry. Clinical, pathological, and cytogenetic characteristics, and treatment responses were compared according to JL1 expression status.

Results

Of the patients with NHL and BM involvement, 37.5% (18/48) were JL1-positive. Among mature B-cell lymphomas, 100%, 38.9%, 33.3%, 100%, and 25.0% of Burkitt lymphomas, diffuse large B-cell leukemias, mantle cell leukemias, Waldenstrom macroglobulinemia, and other B-cell lymphomas, respectively, were JL1-positive. Three mature T- and NK-cell NHLs were JL1-positive. JL1 expression was associated with age (P=0.045), complete response (P=0.004), and BM involvement at follow-up (P=0.017), but not with sex, performance status, the B symptoms, packed marrow pattern, cytogenetic abnormalities, or survival.

Conclusions

JL1 positivity was associated with superior complete response and less BM involvement in NHL following chemotherapy.

Expression of JL1 in Burkitt lymphoma is associated with improved overall survival

JL1 is a novel molecule expressed in the surface of hematopoietic precursor cells, but not on any other mature human tissue. Accordingly, JL1 is expressed in acute lymphoblastic leukemia (ALL) cells and can be used both for specific diagnosis and as a target for treatment. However, expression of JL1 by lymphomas has not been thoroughly assessed. Burkitt lymphoma is a potentially curable aggressive lymphoma, but prognostic markers that stratify risk have not been established. We therefore assayed JL1 expression in Burkitt lymphoma patients to assess its value as a prognostic marker for this disease. Tissue microarray blocks of formalin-fixed paraffin-embedded tissue samples from patients with Burkitt lymphoma and other B-cell lymphomas, at the Asan Medical Center and Seoul National University Hospital from January 1998 to December 2008 were immunohistochemically assayed using a mouse monoclonal antibody against JL1. We found that 30.2% of Burkitt lymphoma samples, but no other lymphoma samples, were positive for JL1. JL-1 expression was significantly correlated with patient survival (P = 0.022), but not with other clinical manifestations of the disease, with 91.6% of JL1-positive patients achieving complete remission in response to chemotherapy and 6.25% experiencing disease recurrence. JL1 positivity was significantly correlated with prolonged overall survival by both Kaplan-Meier survival (P = 0.035) and Cox proportional hazard model (P = 0.043) analysis. JL1 expression in Burkitt lymphoma was positively correlated with overall survival and better response to chemotherapy, suggesting that JL1 may be a prognostic marker for risk stratification in these patients.