Abstract 4634: Anthracycline based antibody-drug conjugates (ADCs) for the treatment of non-Hodgkin's lymphoma are effective in cell lines resistant to auristatin based ADCs.
Authors: Polson Andrew G. , Zheng Bing , Go MaryAnn , Lau Jeffery , Yu Shang-Fan , Spencer Susan , Cohen Robert , Caruso Michele , Flygare John , Polakis Paul 
Published: August 2014

Abstract
Anthracyclines are one of the most widely used classes of chemotherapy. With current success of antibody drug conjugates in the clinic, we were interested in anthracycline-based antibody-drug conjugates (ADCs). Anthracyclines currently used in systemic chemotherapy were ineffective as the ADC drug probably due to low potency of the drug. PNU-159682 was identified as a metabolic product of nemorubicin that was 700 to 2400 more potent in in vivo cytotoxicity assays than nemorubicin. We were interested to see if we could develop an effective anthracycline-based ADC using PNU-159682. For these proof of concept studies we selected the clinically validated linker maleimidocaproyl-valine-citrulline-p-aminobenzoyloxycarbonyl (MC-vc-PAB) used in the approved ADC brentuximab vedotin [anti-CD30-MC-vc-PAB-monomethyl auristatin E (MMAE)] and attached it to the primary alcohol of PNU-159682 to make NMS-249. For antibodies we selected the anti-CD22 and anti-CD79b antibodies that have been shown to be effective as MC-vc-PAB-MMAE ADCs in phase 1 clinical trials for the treatment of NHL. In xenograft models of NHL anti-CD22-NMS249 was as effective or more effective as anti-CD22-MC-vcPAB-MMAE. In particular WSU-DLCL2, where anti-CD22-MC-vc-PAB-MMAE was least effective, show the greatest difference between the two ADCs. To further explore if these the anti-CD22-NMS249 could be used for patients that had progressed on auristatin-based ADC, we developed two cell lines that were resistant to anti-CD22-MC-vc-PAB-MMAE by consistently treating xenograft models with increase amounts of ADC. After removing the resistant tumors and culturing the cells in vitro the cell lines retained their resistance in vivo to anti-CD22-MC-vc-PAB-MMAE but were also resistance to anti-CD79b-MC-vc-PAB-MMAE. This suggests the resistance was not target related and we found that CD22 expression was maintained in the resistant cell lines. Anti-CD22-NMS249 maintained its efficacy in the resistant cell lines. Microarray and FACs showed that the resistant cells lines were up-regulated in MDR1 (PgP). We found that in vivo, unlike other anthacyclines, PNU-159682 was not a PgP substrate this may explain the ability of the anti-CD22-NMS249 to overcome the resistance to anti-CD22-MC-vc-PAB-MMAE. These studies provide poof of concept for an anthracycline ADC that could be use in patients that have failed auristatin-based therapies.
Citation Format: Andrew G. Polson, Bing Zheng, MaryAnn Go, Jeffery Lau, Shang-Fan Yu, Susan Spencer, Robert Cohen, Michele Caruso, John Flygare, Paul Polakis. Anthracycline based antibody-drug conjugates (ADCs) for the treatment of non-Hodgkin's lymphoma are effective in cell lines resistant to auristatin based ADCs. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4634. doi:10.1158/1538-7445.AM2013-4634