DISEASE CHARACTERISTICS:

• Histologically or cytologically confirmed prostate cancer

• Prostate-specific antigen (PSA)-only progression despite androgen deprivation therapy and antiandrogen withdrawal, defined as 3 consecutive rising PSA levels with an interval of > 1 week between each determination AND most recent PSA ≥ 2 ng/mL* within the past 2 weeks

  • Patients receiving luteinizing hormone-releasing hormone (LHRH) agonist therapy must continue LHRH agonist therapy during study participation NOTE: *If the third confirmatory PSA level is < the second level, the patient is considered eligible provided a fourth PSA level is > the second level
• No evidence of local disease progression
• No evidence of metastatic disease
• Must be on concurrent primary androgen deprivation with an LHRH agonist, if no prior orchiectomy

PATIENT CHARACTERISTICS:

Age

• 18 and over

Performance status

• ECOG 0-2

Life expectancy

• More than 6 months

Hematopoietic

• Absolute neutrophil count ≥ 1,500/mm^3
• Platelet count ≥ 100,000/mm^3

Hepatic

• Bilirubin normal
• AST and ALT ≤ 2.5 times upper limit of normal (ULN)

Renal

• Creatinine ≤ 1.5 times ULN

Cardiovascular

• No symptomatic congestive heart failure
• No unstable angina pectoris
• No cardiac arrhythmia

Other

• Testosterone < 50 ng/dL
• Fertile patients must use effective contraception
• No ongoing or active infection
• No psychiatric illness or social situation that would preclude study compliance
• No other uncontrolled illness
• No other currently active malignancy within the past 2 years except nonmelanoma skin cancer or superficial bladder cancer

PRIOR CONCURRENT THERAPY:

Biologic therapy

• No prior cilengitide

Chemotherapy

• Not specified

Endocrine therapy

• See Disease Characteristics
• At least 4 weeks since prior flutamide
• At least 6 weeks since prior bicalutamide or nilutamide
• At least 4 weeks since any other prior therapy intended to treat the cancer except luteinizing hormone-releasing hormone (LHRH) agonists or any stable dose (i.e., on current dosing for ≥ 1 month) of megestrol acetate or corticosteroids

Radiotherapy

• Not specified

Surgery

• At least 4 weeks since prior major surgery

Other

• No other concurrent investigational or commercial agents or therapies for the malignancy

• No concurrent herbal or alternative therapy or food supplements (e.g., PC-SPES, saw palmetto, or Hypericum perforatum [St. John's wort])

  • Concurrent daily multivitamin allowed

• Concurrent bisphosphonates allowed provided dose is stable and was started ≥ 6 weeks ago and patient demonstrates subsequent PSA progression

  • No initiation of bisphosphonate therapy immediately prior to or during study therapy