N,N-diethyl-2-[4-(phenylmethyl)phenoxy]ethanamine in combination with cyclophosphamide: an active, low-toxicity regimen for metastatic hormonally unresponsive prostate cancer.
OBJECTIVE
The intracellular histamine antagonist, N,N-diethyl-2-[4-(phenylmethyl)phenoxy]ethanamine. HCl (DPPE), potentiates chemotherapy cytotoxicity to malignant cells but protects normal tissue, including bone marrow, gut, and hair. We assessed the response to and clinical toxicity of DPPE/cyclophosphamide therapy in 20 patients with advanced hormonally unresponsive prostate cancer, 19 of whom were symptomatic.


METHODS
Subjects received a maximally tolerated dose of DPPE (6 mg/kg) intravenously (IV) over 80 minutes. Cyclophosphamide (600 to 800 mg/m2; maximum dose, 1,500 mg) was administered over the last 20 minutes of DPPE infusion. Treatments (usually outpatient) were given once weekly for 4 weeks, followed by a 1-week delay, and then 2 of every 3 weeks as long as the patient was deemed to benefit.


RESULTS
Five of seven patients (71%) with measurable soft tissue disease had a partial remission (PR). Three of 16 (19%) with assessable bone disease responded (one complete remission [CR] and two PRs). Nine of 18 (50%) with an elevated serum level of prostate-specific antigen (PSA) had more than a 50% (mean +/- SD, 78% +/- 14%) decrease. Eleven of 13 (85%) with bone pain had partial or complete resolution of this symptom; the PSA level and bone scan improved in six and two of these subjects, respectively. Acute treatment toxicity consisted of nausea/vomiting (six of 20) and ataxia (20 of 20), which correlated with peak serum levels of DPPE. Delayed effects (24 to 48 hours) consisted mainly of tiredness and mild nausea; one patient developed hemorrhagic cystitis. Bone marrow and hair follicle toxicity was negligible in 14 and 15 patients, respectively.


CONCLUSIONS
DPPE/cyclophosphamide appears to be an active regimen for metastatic prostate cancer, with the added benefit of relatively low toxicity.
Brandes
L J
LJ
Department of Medicine, Manitoba Cancer Treatment and Research Foundation, Winnipeg, Canada.
Bracken
S P
SP
Ramsey
E W
EW
D000368:Aged; D000369:Aged, 80 and over; D001859:Bone Neoplasms / Q000188:drug therapy / Q000556:secondary; D003520:Cyclophosphamide / Q000009:adverse effects / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010647:Phenyl Ethers / Q000009:adverse effects / Q000627:therapeutic use*; D011471:Prostatic Neoplasms / Q000188:drug therapy*; D012983:Soft Tissue Neoplasms / Q000188:drug therapy / Q000556:secondary
D010647:Phenyl Ethers; D003520:Cyclophosphamide; C043062:tesmilifene