Perifosine in Treating Patients With Metastatic, Androgen-Independent Prostate Cancer

DISEASE CHARACTERISTICS: * Histologically confirmed adenocarcinoma of the prostate, meeting all of the following criteria: * Metastatic * Androgen-independent * Progressive disease while continuing to receive hormonal ablation (e.g., luteinizing hormone-releasing hormone \[LHRH\] agonist) * Progression documented by at least 1 of the following parameters: * Two consecutively rising prostate-specific antigen levels, at least 1 week apart, with at least 1 measurement that is 50% above the nadir reached after the last treatment regimen (as long as the last measurement is at least 5 ng/mL) * At least 1 new metastatic lesion on technetium Tc 99m bone scintigraphy * Progression of soft-tissue metastases as measured by appropriate modalities (i.e., imaging or palpation) and demonstrated by at least 1 of the following: * Development of new area of malignant disease (measurable or nonmeasurable) * At least a 20% increase in the sum of the longest diameters (LD) of target lesions from the smallest sum of LD recorded since the treatment started or the appearance of 1 or more new lesions * Patients who have not undergone surgical castration must have a testosterone level less than 50 ng/mL and continue on their LHRH agonist during study treatment * No known brain metastases PATIENT CHARACTERISTICS: Age * 18 and over Performance status * ECOG 0-2 OR * Karnofsky 60-100% Life expectancy * More than 3 months Hematopoietic * WBC at least 3,000/mm\^3 * Absolute neutrophil count at least 1,500/mm\^3 * Platelet count at least 100,000/mm\^3 Hepatic * Bilirubin less than 1.0 mg/dL or upper limit of normal (ULN) * AST/ALT no greater than 2.5 times ULN Renal * Creatinine no greater than 1.5 mg/dL OR * Creatinine clearance at least 60 mL/min Cardiovascular * No myocardial infarction within the past 6 months * No unstable or newly diagnosed angina pectoris * No New York Heart Association class II-IV congestive heart failure Ophthalmic * No pre-existing retinal disease * No pathologic baseline electrooculogram Other * Fertile patients must use effective barrier contraception * Able to ingest oral medication * No prior allergic reactions attributed to compounds of similar chemical or biological composition to perifosine (e.g., miltefosine or edelfosine) * No ongoing or active infection * No other concurrent uncontrolled illness * No psychiatric illness or social situation that would preclude study compliance * No other active malignancies within the past 2 years except nonmelanoma skin cancer or carcinoma in situ of the bladder PRIOR CONCURRENT THERAPY: Biologic therapy * Not specified Chemotherapy * No more than 1 prior chemotherapy regimen * More than 4 weeks since prior chemotherapy (at least 6 weeks for nitrosoureas or mitomycin) Endocrine therapy * See Disease Characteristics * More than 4 weeks since prior flutamide * More than 6 weeks since prior bicalutamide or nilutamide Radiotherapy * At least 6 weeks since prior bone-seeking radioisotopes * Recovered from prior radiotherapy Surgery * See Disease Characteristics * Recovered from prior surgery Other * Recovered from any acute toxicity related to prior therapy * More than 3 months since prior UCN-01 * More than 3 months since prior suramin * No concurrent commercial or other investigational agents or therapies intended to treat the malignancy * No concurrent combination antiretroviral therapy for HIV-positive patients