Phenelzine beneficial against recurrent castrate-sensitive prostate cancer

The monoamine oxidase inhibitor phenelzine shows therapeutic potential in patients with biochemical recurrent castrate-sensitive prostate cancer, with manageable treatment-related toxicities, according to the results of a phase II trial.

Twenty patients (mean age, 66.9 years) with prostate-specific antigen (PSA) ≥0.4 ng/ml after prostatectomy or ≥2 ng/ml above nadir following radiation therapy (mean PSA, 4.7 ng/dl) received phenelzine 30 mg orally twice daily. None of them had evidence of metastasis on imaging.

A total of 244 cycles were administered, with the target dose of 60 mg/day achieved in 18 patients, five of whom were escalated to 90 mg/day. The median number of treatment cycles delivered per patient was 12.

PSA decreased from baseline by ≥30 percent in five patients (25 percent) and by ≥50 percent in two (10 percent). At week 12, 17 patients remained on treatment, with four exhibiting a PSA decline of ≥30 percent and one a decrease of ≥50 percent.

Commonly reported toxicities were dizziness (grade 1, 45 percent; grade 2, 35 percent), hypertension (grade ≥2, 30 percent) and oedema (grade 1, 25 percent; grade 2, 10 percent). One episode of grade 4 hypertension (at cycle 4) and two episodes of grade 3 syncope (at cycles 12 and 14) led to treatment discontinuation.

With respect to mood symptoms (evaluated using the hospital anxiety depression score questionnaire), treatment produced significant improvements in anxiety but no change in depressive symptoms.

The findings point to monoamine oxidase A as a potential new avenue for treatment in patients with recurrent prostate cancer, researchers said.