Potential new treatment regimen for non-Hodgkin lymphoma from Immunomedics

US biopharmaceutical company Immunomedics (Nasdaq: IMMU) has reported initial clinical experience with a combination of epratuzumab, the Company's humanized anti-CD22 antibody, labeled with the radioisotope, yttrium-90 (90Y), and veltuzumab, the company's humanized anti-CD20 antibody, in patients with relapsed aggressive non-Hodgkin lymphoma (NHL).

Unlike indolent NHL, aggressive NHLs have proven to be more resistant to currently approved antibody therapies unless they are combined with chemotherapy, such as rituximab + CHOP (R-CHOP) for diffuse large B-cell lymphoma (DLCBL) and rituximab + hyper-fractionated CVAD for mantle cell lymphoma (MCL). A significant percentage of these patients who relapsed or become refractory are ineligible for high-dose salvage therapy or stem cell transplant due to advanced age, chemo-resistant disease, and/or concurrent co-morbid medical conditions. Indeed, elderly DLBCL patients who failed R-CHOP have a poor prognosis after disease progression. Thus, there is a considerable need for developing better treatment alternatives for these patients.

A novel approach for NHL therapy that the company is pursuing involves radioimmunotherapy (RAIT) with 90Y-epratuzumab combined with immunotherapy using unlabeled veltuzumab. This is a new therapy concept due to the fact that CD22 and CD20 are distinct antigens. Consequently, anti-CD20 antibodies would not cross-block anti-CD22 RAIT, which, at least in the case of DLBCL, could allow for more effective consolidation with anti-CD22 RAIT after R-CHOP therapy.