Therapeutic potential of an anti-CCR9 mAb evidenced in xenografts of human CCR9+ tumors

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Relapsed or refractory T acute lymphoblastic leukemia (T-ALL) still carries poor prognosis. Aiming to improve outcomes, the therapeutic potential of an anti-CCR9 monoclonal antibody (mAb 92R), targeting the human chemokine-receptor CCR9 is analyzed on orthotopic xenotransplants. 92R mAb treatment of mice carrying human CCR9+ T-ALL cell lines or primary T cell leukemias inhibits tumor growth and increases survival. The therapeutic effects of 92R are specific and synergize with chemotherapeutic agents increasing survival. Furthermore, 92R decreases size of non-hematopoietic tumors with a forced CCR9 expression and of solid tumors generated by the pancreatic adenocarcinoma cell line AsPC-1. In addition, a humanized version of 92R mAb (Srb1) is also able to inhibit growth of CCR9+ T-ALL tumor cells in vivo, increasing survival 2.66-fold. Finally, 92R mAb prevents liver accumulation of infiltrates and reduces tumor cell numbers in already formed infiltrates. Thus, the humanized version of 92R mAb (Srb1), displays therapeutic potential for CCR9+ tumor treatment and might represent one of the first therapeutic antibodies for precision medicine on T-ALL patients.
The work in the author’s laboratories was partially supported by grants from the PN2014-A from the ISCIII (PI14/00703, co-financed by FEDER funds from the EU, Operative program on Intelligent Growth 2014-2020, to LK); the Spanish Ministry of Economy, Industry and Competitiveness (RTC-2015-3786-1 to LK and JG-S), co-financed by FEDER funds from the EU and from the Spanish Ministry of Science and Innovation (PID2019-105404RB-I00 to JAGS and LK financed by MCIN/AEI/10.13039/501100011033). As well as the CSIC (PIE-201420E109 and PIE-201720E092, to LK).