Fig S1. ELISA formats for detection of various analytes. Fig S2. Biophysical characterization of CAT-02-106. Fig S3. Competitive ELISA data showing CAT-02-106 binding to CD22. Fig S4. CAT-02-106 internalization on Ramos, Granta-519, and WSU-DLCL2 cells. Fig S5. CAT-02-106 in vitro cytotoxicity test on CD22-negative cells. Fig S6. The CAT-02-106-related ADC, anti-HER2 RED-106, does not induce bystander killing. Fig S7. Comparison of cell surface CD22 expression levels on Ramos and WSU-DLCL2 cells. Fig S8. Ramos and WSU-DLCL2 xenograft study data plotted as individual animals. Fig S9. Mouse body weights from Ramos and WSU-DLCL2 xenograft studies. Fig S10. CAT-02-106 binding to cynomolgus monkey B cells as assessed by flow cytometry. Fig S11. CAT-02-106 cross-reactivity to human and cynomolgus tissues. Table S1. Summary of pharmacokinetic findings in rats dosed at 3 mg/kg with CAT-02-106.