Rapid Eradication of Extensive Spinal Metastases in a Prostate-Cancer Patient Taking Androgen-deprivation Therapy, Chemotherapy, and Oral Recombinant Methioninase on a Low-Methionine Diet.

[BACKGROUND/AIM] Bone metastasis of prostate cancer is a recalcitrant disease treated by androgen-deprivation therapy (ADT), chemotherapy, and radiation. We have previously shown that methionine restriction with oral recombinant methioninase (o-rMETase) alone or in combination with chemotherapeutic agents was apparently effective for prostate-cancer patients, including a patient with extensive bone metastases. In the present study, we described a patient with spinal metastases of prostate cancer treated with ADT, chemotherapy with docetaxel, and methionine restriction with o-rMETase and a low-methionine diet.

[CASE REPORT] The present report is on a 62-year-old male prostate-cancer patient with a history of prostatectomy who was subsequently diagnosed by prostate specific membrane antigen (PSMA)-PET imaging to have extensive spinal metastases. The patient then received combination therapy with ADT (relugolix and darolutamide), docetaxel chemotherapy, o-rMETase (twice a day 250 units, 5 mg), and a low-methionine diet. Six months later, a second PSMA-PET demonstrated marked regression of metastases, with only residual uptake in the cervical spine. At nine months, [C]methionine-PET confirmed complete disappearance of the residual lesion, and no distant metastases were detected. The present findings suggest remission of spinal metastases from prostate cancer.

[CONCLUSION] The patient achieved an apparent complete response of prostate-cancer spinal metastases after treatment with ADT, chemotherapy, and methionine restriction. Further studies, including controlled clinical trials are necessary to validate this new paradigm of treatment for prostate-cancer bone metastases.