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Oxazaphosphorine effects in L 5222 rat leukemia
J Pohl1, T Reissmann, R Voegeli
1Abteilung Tumorforschung, Asta-Werke AG, Degussa Pharma Gruppe, Bielefeld, FRG.
Methods and Findings in Experimental and Clinical Pharmacology
|September 1, 1987
Summary
Low doses of oxazaphosphorines, like mafosfamide, show therapeutic effects against tumors by stimulating the immune system. This immunoaugmenting effect, mediated by T-cells, is dose-dependent and crucial for cancer immunotherapy.
Area of Science:
- Immunology
- Pharmacology
- Oncology
Background:
- Clinical reports suggest cyclophosphamide's anti-tumor efficacy involves host immune mechanisms.
- This effect is dose-dependent, with low doses immunostimulating and higher doses immunosuppressing.
Purpose of the Study:
- To find an experimental model for the immunoaugmenting effects of oxazaphosphorines.
- To investigate the dose-response relationship and compare cyclophosphamide with mafosfamide.
Main Methods:
- Utilized a transplantable leukemia L 5222 model in BD IX rats.
- Conducted dose-response studies with cyclophosphamide and mafosfamide.
- Performed in vitro studies on T-suppressor cell proliferation.
Main Results:
- Low-dose oxazaphosphorines cured leukemia in rats, with efficacy decreasing at higher doses.
- A bell-shaped dose-response pattern was observed for cyclophosphamide and mafosfamide.
- Mafosfamide demonstrated a broader immunotherapeutic range than cyclophosphamide.
- Mafosfamide inhibited T-suppressor cell proliferation in vitro, suggesting a T-cell mediated mechanism.
- Treated animals developed immunity to subsequent tumor challenges.
Conclusions:
- Low-dose mafosfamide exhibits potent immunotherapeutic effects against tumors, likely via T-cell modulation.
- The optimal immunopharmacological dose is significantly lower than the maximally tolerated clinical dose.
- Mafosfamide is a promising candidate for cancer immunotherapy, with ongoing clinical trials.