Related Experiment Videos
In vivo toxicity, pharmacokinetics, and anticancer activity of Genistein linked to recombinant human epidermal growth
Abstract:
Epidermal growth factor receptor (EGFR)-associated protein tyrosine kinase (PTK) complexes have vital anti-apoptotic functions in human breast cancer cells. We have shown previously that targeting the naturally occurring PTK inhibitor genistein to the EGFR-associated PTK complexes using the EGF-Genistein (Gen) conjugate triggers rapid apoptotic cell death in human breast cancer cells and abrogates their in vitro clonogenic growth. In the present study, we examined the in vivo toxicity profile, pharmacokinetics, and anticancer activity of EGF-Gen. No toxicities were observed in mice treated with EGF-Gen at dose levels as high as 40 mg/kg administered i.p. as a single dose or 140 mg/kg administered i.p. over 28 consecutive days. EGF-Gen significantly improved tumor-free survival in a severe combined immune deficiency (SCID) mouse xenograft model of human breast cancer, when it was administered 24 h after inoculation of tumor cells. At 100 microg/kg/day x 10 days (1 mg/kg total dose), which is >100-fold less than the highest tested and nontoxic cumulative dose (ie., 140 mg/kg) in mice, EGF-Gen was more effective than cyclophosphamide (50 mg/kg/day x 2 days), Adriamycin (2.5 mg/kg x 1 day), or methotrexate (0.5 mg/kg x 1 day), the most widely used standard chemotherapeutic drugs for breast cancer, and resulted in 60% long-term tumor-free survival. Furthermore, treating SCID mice with established s.c. human breast cancer xenografts of 0.5-cm diameter with EGF-Gen at this dose level resulted in disappearance of the tumors in two of five mice and >50% shrinkage in three of five mice within 10 days, whereas all of the control tumors in five PBS-treated mice as well as five mice treated with unconjugated Gen (1 mg/kg/day x 10 days) showed >200% increase in diameter during the same observation period. EGF-Gen treatment reduced the growth rate of breast cancer xenografts of 1.0-cm diameter, but unlike with tumors of 0.5-cm diameter, it failed to cause shrinkage or disappearance of these larger tumors. The level of EGF-Gen systemic exposure that was effective in SCID mice was achieved in cynomolgus monkeys without any significant side effects detectable by clinical observation, laboratory studies, or histopathological examination of multiple organs. EGF-Gen might be useful in the treatment of breast cancer as well as other EGFR-positive malignancies.
Insights
The novel EGF-Gen conjugate effectively targets epidermal growth factor receptor (EGFR)-associated protein tyrosine kinase (PTK) complexes, inducing apoptosis in breast cancer cells. This conjugate demonstrated significant anti-tumor activity in vivo with no observed toxicity in mice and monkeys.
Area of Science:
- Oncology
- Molecular Biology
- Pharmacology
Background:
- Epidermal growth factor receptor (EGFR)-associated protein tyrosine kinase (PTK) complexes are crucial for human breast cancer cell survival.
- Targeting these complexes with PTK inhibitors can induce apoptosis and inhibit cancer growth.
Purpose of the Study:
- To evaluate the in vivo toxicity, pharmacokinetics, and anticancer efficacy of the EGF-Gen conjugate.
- To assess the potential of EGF-Gen as a therapeutic agent for breast cancer and other EGFR-positive malignancies.
Main Methods:
- Toxicity and pharmacokinetic studies were conducted in mice and cynomolgus monkeys.
- Anticancer activity was assessed using severe combined immune deficiency (SCID) mouse xenograft models of human breast cancer.
- EGF-Gen efficacy was compared against standard chemotherapeutic drugs like cyclophosphamide, Adriamycin, and methotrexate.
Main Results:
- EGF-Gen exhibited no toxicity in mice at high doses (up to 140 mg/kg).
- EGF-Gen significantly improved tumor-free survival in SCID mice, achieving 60% long-term survival at a dose of 1 mg/kg total.
- Complete tumor disappearance was observed in 40% of mice with established xenografts, and significant shrinkage in others, outperforming standard chemotherapies.
Conclusions:
- EGF-Gen demonstrates a favorable safety profile and potent anticancer activity against human breast cancer xenografts.
- The conjugate shows promise as a novel therapeutic strategy for breast cancer and other EGFR-driven cancers.
- Further clinical investigation of EGF-Gen is warranted for its therapeutic potential.