On May 30, 2019 OncBioMune Pharmaceuticals, Inc. (OTCQB:OBMP) ("OncBioMune" or the "Company"), a clinical-stage biopharmaceutical company engaged in the development of a proprietary therapeutic prostate cancer vaccine immunotherapy and a CD71-targeted cancer therapy combining paclitaxel, gallium, and transferrin, otherwise known as PGT, reported the results of initial in vitro data for PGT in a Multi-drug resistant ovarian cancer model (Press release, Oncbiomune, MAY 30, 2019, View Source [SID1234536719]).

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Cell proliferation assays were performed on 2 cell lines, MCF-7 (a breast cancer cell line known to be sensitive to chemotherapy) and NCI/ADR-RES (OVCAR-8 ADR-RES, a multidrug-resistant cell line that is a model for the study of drug resistance in ovarian cancer) grown under hypoxic conditions and treated separately with varying concentrations of either the standard chemotherapy agent paclitaxel or PGT for 72 hours. The IC50 (concentration of drug needed to inhibit the cell growth by 50%) was determined for paclitaxel and PGT, standardized by the concentration of paclitaxel. The IC50s were calculated from growth inhibition curves.

The IC50s for the MCF-7 cells were similar for paclitaxel and PGT (range 0.02 to 0.09 micromolar). However, the IC50 of the NCI/ADR-RES cells for the paclitaxel was 216 micromolar and the IC50 for the PGT was 0.0318 micromolar. This shows that in this experiment, a 6797-fold decrease in the concentration of PGT can obtain the same inhibition of cancer cell growth as the standard chemotherapy paclitaxel in this multidrug-resistant model. Additionally, this concentration of PGT is similar to the IC50 of paclitaxel seen in the chemotherapy sensitive MCF-7 cells. Taken together, this implies that PGT is able to overcome drug resistance mechanisms at play in the NCI/ADR-RES cell line model of chemotherapy resistance and thereby makes these cells sensitive to PGT therapy in an acceptable concentration range.

PGT is designed to deliver the chemotherapeutic agent paclitaxel to cancer cells over-expressing the transferrin receptor (aka CD71). Paclitaxel is currently FDA-approved in two forms: as solvent-based paclitaxel (sb-paclitaxel, Taxol) and protein-based paclitaxel (nab-paclitaxel, ABRAXANE ).

PGT combines paclitaxel to the human protein transferrin as opposed to albumin, which is employed in nab-paclitaxel. This creates the potential to target the paclitaxel to CD71, which has been shown to be highly over-expressed on many different types of cancer cells.

Additionally, PGT takes advantage of the fact that the transferrin protein has binding sites for iron that can also bind gallium, which has anti-cancer activity. In theory, this creates a novel protein drug complex which has the capacity to deliver two, non-cross resistant cancer therapeutics in a targeted fashion.

"This is only one experimental model, but it does suggest that PGT has the potential to show activity in cancer cells that are resistant to standard chemotherapies that are used widely in patients today," commented Dr. Brian Barnett, Chief Executive Officer at OncBioMune. "This experiment utilizes a well characterized ovarian cancer cell line that is multi-drug resistant. In the near future, we plan to perform tests on other models as we are hopeful that this therapy may show broad activity in multiple cancer types with the ultimate goal of developing PGT for patients with refractory cancers, an area of high unmet medical need."