CD20-Directed Small Modular Immunopharmaceutical, TRU-015, Depletes Normal and Malignant B Cells

Abstract

Purpose: CD20-directed therapy with rituximab is effective in many patients with malignant lymphoma or follicular lymphoma. However, relapse frequently occurs within 1year, and patients become increasingly refractory to retreatment. Our purpose was to produce a compact, single-chain CD20-targeting immunotherapeutic that could offer therapeutic advantages in the treatment of B-cell lymphoma. Experimental Design: Rituximab is a chimeric antibody containing two heavy chains and two light chains. Here, we describe the properties of TRU-015, a small modular immunopharmaceutical specific for CD20, encoded by a single-chain construct containing a single-chain Fv specific for CD20 linked to human IgG1hinge, CH2, and CH3 domains but devoid of CH1and CL domains. Results: TRU-015 mediates potent direct signaling and antibody-dependent cellular cytotoxicity but has reduced size and complement-mediated cytotoxicity activity compared with rituximab. TRU-015 is a compact dimer of 104 kDa that comigrates with albumin in size exclusion chromatography and retains a long half-life in vivo.TRU-015 induced growth arrest in multiple B lymphoma cell lines in vitro and showed effective antitumor activity against large, established subcutaneous Ramos or Daudi xenograft tumors in nude mice. TRU-015 also showed rapid, dose-dependent, and durable depletion of peripheral blood B cells following single-dose administration to nonhuman primates. Conclusion: These results indicate that TRU-015 may improve CD20-directed therapy by effectively depleting embedded malignant B cells and nonmalignant pathogenic B cells and do so with reduced complement activation.

Fc-fusion proteins and FcRn: structural insights for longer-lasting and more effective therapeutics

“…TRU-015, engineered as a fusion of a single-chain Fv specific for CD20 to an Fc fragment devoid of CH1 and CL has, by design, a decreased ability to engage complement components and complement-dependent cytotoxicity but retains strong antibody-dependent cytotoxicity (ADCC) and potent direct signaling activity in vivo (Burge et al, 2008). It has been shown that it can effectively deplete B lymphocytes in a dose-dependent manner in non-human primates and improve survival in mouse xenograft tumor models (Hayden-Ledbetter et al, 2009). In an open-label dose escalation phase I trial in patients with RA, TRU-015 was associated with dose-dependent B-cell depletion and found to have an acceptable tolerability profile (Burge et al, 2008).…”

Evolution of anti- CD20 monoclonal antibody therapeutics in oncology

“…TRU-015, is another third generation anti-CD20 molecule that is a small modular immunopharmaceutical drug composed of human IgG1 Fc and CH2 and CH3 hinge regions linked directly to an anti-CD20 scFv. [56][57][58] It is slightly smaller than an IgG and has high ADCC and low complement activating ability. It is currently in Phase 2 clinical development for RA.…”

Update on Biologic Therapies for Systemic Lupus Erythematosus

“…A small modular immunopharmaceutical (SMIP) is a singlechain peptide construct, smaller than a mAb, which contains an antigen-binding (variable) domain, a hinge, and an effector domain, such as an Ig constant region, selected according to a specific therapeutic purpose [138]. Intravenous administration of an anti-CD20 SMIP, 2LM20-4, induced a more sustained B cell depletion than did rituximab in a preclinical cynomolgus monkey study [139].…”