Supplementary Methods, Figures S1-S10, and Table S1 from Caveolae-Mediated Endocytosis as a Novel Mechanism of Resistance to Trastuzumab Emtansine (T-DM1)

Supplementary Figure S1: N87 and N87-TM cells are similarly sensitive to unconjugated DM1-SMe; Supplementary Figure S2: Trastuzumab binding to N87 and N87-TM cells; Supplementary Figure S3: Generation and characterization of T-DM1-resistant HCC1954-TM and BT474-TM cells; Supplementary Figure S4: Relative resistance profiles of N87-TM to N87 cells to T-ADCs, unconjugated payloads and standard-of-care chemotherapeutics; Supplementary Figure S5: Distribution of T-ADCs in N87-TM tumors; Supplementary Figure S6: N87-TM cells are cross-resistant to a T-ADC conjugated to a cleavable linker with a cysteine-capped auristatin analog; Supplementary Figure S7: N87-TM cells internalize T-ADC into non-low pH intracellular compartments; Supplementary Figure S8: CAV1-GFP expression causes intracellular caveolae formation capable of internalizing T-ADCs in N87 cells; Supplementary Figure S9: CAV1 knockdown is not sufficient to re-sensitize N87-TM cells to T-DM1; Supplementary Figure S10: Non-cleavable and cleavable T-ADCs co-localize with CAV1 similarly in N87 and N87-TM cells; Supplementary Table S1. Cytotoxicity values of Trastuzumab and isotype-control ADCs in HT29 cells, a HER2-negative cell line