Journal: Molecular Cancer Therapeutics
Article Title: Preclinical Development of SGN-CD47M: Protease-Activated Antibody Technology Enables Selective Tumor Targeting of the Innate Immune Checkpoint Receptor CD47
doi: 10.1158/1535-7163.MCT-24-0371
Figure Lengend Snippet: A protease-activated antibody approach using coiled-coil masking peptides improves the PK and tolerability of an antibody directed to mouse CD47. A, Masking impaired the binding of mIAP301 to mouse CD47 on HT-2 cells but could be restored upon cleavage with recombinant MMP. Symbols represent duplicate samples shown as mean ± SD. A, Decreased binding resulted in impaired RBC phagocytosis ( B ) in vitro . Representative data from three independent experiments. Symbols represent the mean ± SD from three biological replicates. *, P < 0.05; ***, P < 0.001 (one-way ANOVA followed by the Dunnett multiple comparisons test) compared with mIAP301. C, PK profiles of unmasked mIAP301 and Coil-MMP-mIAP301 in naïve BALB/c mice, which demonstrates strikingly different plasma exposure profiles because of avoidance of the large normal tissue sink for CD47. The dotted line denotes the level of quantitation in the experiment. It should be noted that the concentration of mIAP301 was only at or above the level of quantitation at the 15-minute time point. Symbols indicate n = 3 replicates and are shown as the mean ± SD. LOQ, level of quantitation. D , Antitumor activity of masked and unmasked mIAP301 antibodies was assessed in an A20 lymphoma model in BALB/c mice and showed similar antitumor activity (every two days for 8 cycles i.p. dosing). Error bars represent mean ± SD ( n = 6 mice per group). Statistical assessment for pairwise comparisons of tumor growth inhibition between treatment arms is provided in Supplementary Fig. S3. In tumor-bearing mice, masking decreased RBC depletion ( E ), and a comparison of bound antibody on RBCs vs. tumor cells provides evidence for tumor-specific mask activation ( F ). Data shown in E and F , are representative of two individual experiments. Symbols represent three biological replicates and are shown as the mean ± SD. *, P < 0.05; ***, P < 0.01; ***, P < 0.001 (one-way ANOVA followed by the Tukey multiple comparisons test) compared with mIAP301.
Article Snippet: Saturation binding ELISA experiments were performed using soluble recombinant human, mouse, or cyno CD47 (ACROBiosystems), which was diluted to an appropriate concentration in 50 mmol/L carbonate buffer at pH 9.6.
Techniques: Binding Assay, Recombinant, In Vitro, Clinical Proteomics, Quantitation Assay, Concentration Assay, Activity Assay, Inhibition, Comparison, Activation Assay