biostudies-literaturePaul MRNICHD NIH HHSNCATS NIH HHSe546-e549https://www.ebi.ac.uk/biostudies/studies/S-EPMC7216755biostudies-literatureUnknown41(8)<h4>Background</h4>Inotuzumab ozogamicin is a novel antibody-drug conjugate that targets CD22, a common antigen on pre-B acute lymphoblastic leukemia cells.<h4>Observations</h4>A 7-year-old boy with pre-B acute lymphoblastic leukemia in his second relapse was given 2 cycles of inotuzumab ozogamicin. He responded morphologically with a negative bone marrow evaluation. However, he relapsed in cycle 3 of therapy with a loss of CD22 expression on his lymphoblast population.<h4>Conclusion</h4>To our knowledge, this is the first published case of CD22 expression loss as a mechanism of therapy resistance for inotuzumab ozogamicin.Journal of pediatric hematology/oncologyTreatment of Recurrent Refractory Pediatric Pre-B Acute Lymphoblastic Leukemia Using Inotuzumab Ozogamicin Monotherapy Resulting in CD22 Antigen Expression Loss as a Mechanism of Therapy Resistance.PMC7216755TL1 TR001443T32 HD087978Wong VPaul MRAristizabal PKuo DJfalseTreatment of Recurrent Refractory Pediatric Pre-B Acute Lymphoblastic Leukemia Using Inotuzumab Ozogamicin Monotherapy Resulting in CD22 Antigen Expression Loss as a Mechanism of Therapy Resistance.<h4>Background</h4>Inotuzumab ozogamicin is a novel antibody-drug conjugate that targets CD22, a common antigen on pre-B acute lymphoblastic leukemia cells.<h4>Observations</h4>A 7-year-old boy with pre-B acute lymphoblastic leukemia in his second relapse was given 2 cycles of inotuzumab ozogamicin. He responded morphologically with a negative bone marrow evaluation. However, he relapsed in cycle 3 of therapy with a loss of CD22 expression on his lymphoblast population.<h4>Conclusion</h4>To our knowledge, this is the first published case of CD22 expression loss as a mechanism of therapy resistance for inotuzumab ozogamicin.2019-01-01T00:00:00Z2019 Nov2025-04-25T22:58:08.469Z2020-11-04T08:04:24ZS-EPMC72167553080739510.1097/mph.000000000000144010.1097/MPH.0000000000001440