Chronic Treatment of an Advanced Prostate-cancer Patient With Oral Methioninase Resulted in Long-term Stabilization of Rapidly Rising PSA Levels

Abstract

Background/aim: Advanced prostate cancer is a recalcitrant disease with very limited treatment options. Our laboratory discovered methionine addiction, presumably a characteristic of all cancer types, including prostate cancer, which can be targeted by methionine restriction (MR), through treatment with oral recombinant methioninase (o-rMETase).

Patients and methods: o-rMETase was produced by fermentation of recombinant E. coli containing the Pseudomonas putida methioninase gene, and purified by column chromatography. An advanced prostate cancer patient received o-rMETase as a supplement, 500 units per day, divided into two oral doses of 250 units each.

Results: Before treatment, the patient had a rapid rise in PSA levels, from 39 to 56 ng/ml, within 6 weeks. At the 15^th week of o-rMETase administration, the PSA levels stabilized at 62 ng/ml. No overt side effects were observed.

Conclusion: o-rMETase single treatment can be beneficial for advanced prostate cancer patients.

Keywords: Methioninase; PSA; advanced prostate-cancer patient; methionine addiction; oral.