IDEC-C2B8: results of a phase I multiple-dose trial in patients with relapsed non-Hodgkin's lymphoma

To evaluate the safety, pharmacokinetics, and biologic effect of multiple doses of the chimeric anti-CD20 monoclonal antibody (mAb) IDEC-C2B8 in patients with relapsed B-cell lymphoma.

Twenty patients with relapsed low-grade (n = 15) or intermediate-/high-grade (n = 5) lymphoma received weekly infusions times four of 125 mg/m2 (n = 3), 250 mg/m2 (n = 7), or 375 mg/m2 (n = 10) of IDEC-C2B8.

Infusional side effects during the initial infusion were mainly grade I/II fever, asthenia, chills, nausea, rash, and urticaria. More serious events were rare. Peripheral-blood B cells were rapidly depleted and slowly recovered over 3 to 6 months. There was no change in mean immunoglobulin (Ig) levels. Antibody serum half-life (and maximum concentration [Cmax]) generally increased between the first and fourth infusions (33.2 hours v 76.6 hours, respectively) following the 375-mg/m2 doses. Six of 18 assessable patients had a partial remission (PR), with a median time to disease progression of 6.4 months (range, 3 to 21.7). Minor responses (MRs) were observed in five patients and progressive disease (PD) in seven. Tumor responses occurred in peripheral blood, bone marrow (BM), spleen, bulky lymph nodes, and extranodal sites, and in patients who had relapsed following high-dose myeloablative chemotherapy. Six of 14 patients (40%) with a low-grade histology responded. Four of six with bulky disease had a PR.

IDEC-C2B8 chimeric anti-CD20 mAb therapy is well tolerated and has clinical activity in patients with relapsed B-cell lymphoma. The 375-mg/m2 dose has been selected for a phase II trial in patients with relapsed low-grade or follicular B-cell lymphoma.