Gene targeting strategy for B-hFOLR1 MC38 cells. The human FOLR1 coding sequence was inserted into the exon 4 of mouse Folr1 in B-hFOLR1 MC38 cells. The insertion disrupts the endogenous murine Folr1 gene, resulting in a non-functional transcript.

FOLR1 expression analysis in B-hFOLR1 MC38 cells by flow cytometry. Single cell suspensions from wild-type MC38 and B-hFOLR1 MC38 cultures were stained with species-specific anti-FOLR1 antibody. Human FOLR1 was detected on the surface of B-hFOLR1 MC38 cells but not wild-type MC38 cells. The 1-F01 clone of B-hFOLR1 MC38 cells was used for in vivo experiments.

Subcutaneous homograft tumor growth of B-hFOLR1 MC38 cells. B-hFOLR1 MC38 cells (1x10⁶) and wild-type MC38 cells (5x10⁵) were subcutaneously implanted into C57BL/6 mice (female, 8-week-old, n=6). Tumor volume and body weight were measured twice a week. (A) Average tumor volume ± SEM. (B)  Body weight (Mean± SEM). Volume was expressed in mm³ using the formula: V=0.5 X long diameter X short diameter². As shown in panel A, B-hFOLR1 MC38 cells were able to establish tumors in vivo and can be used for efficacy studies.

B-hFOLR1 MC38 tumor cells growth of individual mice. B-hFOLR1 MC38 cells (1x10⁶) and wild-type MC38 cells (5x10⁵) were subcutaneously implanted into C57BL/6 mice (female, 8-week-old, n=6). As shown in panel, B-hFOLR1 MC38 cells were able to establish tumors in vivo and can be used for efficacy studies.

B-hFOLR1 MC38 cells were subcutaneously transplanted into C57BL/6 mice (n=6), and on 31 days post inoculation, tumor cells were harvested and assessed for human FOLR1 expression by flow cytometry. As shown, human FOLR1 was highly expressed on the surface of tumor cells. Therefore, B-hFOLR1 MC38 cells can be used for in vivo efficacy studies of novel FOLR1 therapeutics.