Epratuzumab (Anti-CD22 Humanized Monoclonal Antibody) Is an Active and Well-Tolerated Therapy for Refractory/Relapsed Diffuse Large B-Cell Non-Hodgkin’s Lymphoma

Patients with refractory/relapsed diffuse large B-cell non-Hodgkin’s lymphoma (NHL) who fail high-dose chemotherapy and stem cell transplant or are not suitable candidates for intensive therapy have limited therapeutic options. We have conducted a phase I/II clinical trial of epratuzumab (hLL2 [LymphoCide]), a humanized monoclonal antibody directed against the B-cell-specific antigen CD22, in patients with previously treated indolent and aggressive NHL.

Patients received doses of epratuzumab administered in four weekly infusions (30 to 60 minutes each) on an outpatient basis and were observed for toxicity and response. Initial findings have demonstrated this schedule to be well tolerated with clear activity in several NHL subtypes. We now report results specifically from patients with refractory/relapsed diffuse large B-cell NHL.

To date, 24 patients with this NHL subtype have been enrolled, with 17 currently evaluable. Patients had a median age of 60 years (range: 19 to 88 years), with a median of 4 prior treatment regimens (range: 2 to 9 regimens). Baseline lactate dehydrogenase was elevated in 65% of subjects. Fifty-three percent of patients had relapsed after high-dose chemotherapy and stem cell transplant, while 47% were refractory/relapsed after prior rituximab (Rituxan) treatment. Infusions of 240 to 1,000 mg/m²/wk were well tolerated in all patients, with occasional mild infusion reactions but no grade III/IV toxicity noted.

Objective responses have been noted in 5/17 patients (29%): 2 complete responses (11%) and 3 partial responses (18%), with tumor shrinkage observed in several other subjects (including a 45% decrease in the sum of the products of perpendicular diameters [SPPD] of lesion measurements in one additional individual). Response durations have ranged from 3 to 24+ months, with 4 of 5 responses ongoing. Responding patients had a median of 4 prior regimens (range: 3 to 5 regimens), and included 3 patients who relapsed after high-dose chemotherapy and stem cell transplant and 2 patients who were not transplant candidates (ages 82 and 88).

CONCLUSION: Epratuzumab is a well-tolerated and active agent in heavily pretreated patients with diffuse large B-cell lymphoma. Studies are ongoing to define the optimal setting for its use in aggressive NHL.

Click here to read Dr. Bruce Cheson's commentary on this abstract.