In vitro studies using a variety of human cell lines have been used to assess the effectiveness of antineoplastons as antineoplastic agents. Burzynski states that antineoplaston A is species-specific because it had no therapeutic effect when the human preparation was tested on animal tumor systems. Although this finding limits the usefulness of animal model testing, the developer has suggested that a “marked” therapeutic effect was produced in a xenograft bearing human tumor tissue. This claim is made only for antineoplaston A. Other formulations of antineoplastons have not been tested in animal models.
Japanese scientists have tested antineoplastons A10 and AS2-1 in vitro for cell growth inhibition and progression in several human hepatocellular cell lines.[2,3] Tests were performed in a dose-dependent manner at concentrations varying from 0.5 to 8 µg/mL for A10 and AS2-1, and growth inhibition was generally observed at 6 to 8 µg/mL. This dose level is considered excessively high and generally reflects a lack of activity. Growth inhibition of one of the cell lines (KIM-1) was observed at low concentration for a mixture of cisplatin (CDDP) and A10, but this result was probably caused by the cisplatin, which was effective at concentrations of 0.5 to 2.0 μg/mL when tested alone. AS2-1 was reported to induce apoptosis in three of the cell lines at concentrations of 2 and 4 μg/mL.
Antineoplaston A10 was also shown to inhibit prolactin or interleukin-2 stimulation of mitogenesis in a dose-dependent manner in rat Nb2 lymphoma cell line. The addition of A10 (1–12 mm) to prolactin-stimulated cells inhibited growth but was reversible when A10 was removed, suggesting a cytostatic rather than cytotoxic mechanism of action. A10 also showed no toxicity in a chromium release assay. DNA synthesis was also inhibited by A10.
The ability of antineoplaston A3, isolated from urine and not an analog, to inhibit the growth of the HBL-100 human breast cancer cell line in vitro was investigated in a study that also examined the toxicity of A3 in Swiss white mice. Antineoplaston A3 inhibited colony formation in a dose-dependent manner over a dose range of 0.05, 0.1, 0.2, and 0.4 µg/mL.
A somewhat different approach to the use of A10 was taken by researchers in Egypt. Taking the developer’s initial ideas about the presence of A10 in the urine of patients, this study looked for the amount of A10 in the urine of 31 breast cancer patients and compared this to the amount in 17 healthy controls. They found significantly (P < .001) less A10 in the urine of breast cancer patients than in controls, suggesting that the amount of A10 in urine has a potential use as a screening tool.
The same researchers looked at the immunomodulating potential of A10 by examining the inhibition of neutrophil apoptosis induced by A10 in vitro. Neutrophils from 28 breast cancer patients and 28 controls were obtained from blood samples. Urine samples were obtained from the same patients and tested for the presence of A10. Cancer patients had significantly (P < .001) higher levels of neutrophil apoptosis and significantly lower levels of A10. Neutrophil apoptosis was assessed by adding A10 at a dose of 10 µg/mL to the cellular suspensions of 42 breast cancer patients. Nontreated samples were used as controls. A10 was found to significantly inhibit neutrophil apoptosis (P < .0001).
Several analogs of antineoplaston A10 have been synthesized and their antineoplastic activity tested against various cell lines. These include aniline mustard analogs of antineoplaston A10 and Mannich bases of antineoplaston A10.[9,10] These analogs showed improved in vitro antitumor activity over that of antineoplaston A10.References
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- Tsuda H: Inhibitory effect of antineoplaston A-10 on breast cancer transplanted to athymic mice and human hepatocellular carcinoma cell lines. The members of Antineoplaston Study Group. Kurume Med J 37 (2): 97-104, 1990. [PUBMED Abstract]
- Tsuda H, Iemura A, Sata M, et al.: Inhibitory effect of antineoplaston A10 and AS2-1 on human hepatocellular carcinoma. Kurume Med J 43 (2): 137-47, 1996. [PUBMED Abstract]
- Tsuda H, Sugihara S, Nishida H, et al.: The inhibitory effect of the combination of antineoplaston A-10 injection with a small dose of cis-diamminedichloroplatinum on cell and tumor growth of human hepatocellular carcinoma. Jpn J Cancer Res 83 (5): 527-31, 1992. [PUBMED Abstract]
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