Inclusion Criteria

Inclusion Criteria Phase I Part:

- Adult males ≥18 years of age.

- Patients with CRPC defined as confirmed rise of PSA levels after orchiectomy or LHRH
agonist based therapy.

- Progressive disease, defined as PSA progression by confirmed rising PSA levels.

- PSA at time of study entry ≥2ng/ml within 1 week prior to treatment (according to
Scher 2008).

- Bone metastasis and/or lymph node and/or visceral organ metastases allowed.
Measurable and non measurable disease allowed.

- Performance status (PS) 0-1 ECOG.

- Signed written informed consent.

- White blood cell count (WBC) ≥4x10^9/L with neutrophils ≥1.5x10^9/L, platelet count
≥100x10^9/L, hemoglobin ≥9g/dL.

- Total bilirubin <=2 x upper limit of normal.

- AST and ALT <=2.5 x upper limit of normal, or <=5 x upper limit of normal in case of
liver metastases.

- Serum creatinine <=1.5 x upper limit of normal or creatinine clearance > 60 ml/min.

- Androgen ablation will have to be continued. Antiandrogens such as bicalutamide will
have to be discontinued at least 4 weeks prior to the start of study treatment.

Exclusion Criteria Phase I Part:

- Clinically symptomatic brain or meningeal metastasis.

- Receiving known strong CYP3A4 isoenzyme inhibitors and/or inducers.

- Any investigational drug within the 30 days before inclusion.

- Not recovered from prior biopsy, surgery, traumatic injury, and/or radiation therapy,
as judged by the investigator.

- Nonhealing wound or ulcer.

- Grade ≥ 3 hemorrhage within the past month.

- Any condition / concomitant disease not allowing chemotherapy with docetaxel,
prednisone and temsirolimus in the discretion of the treating physician, like: Renal
insufficiency requiring dialyses; congestive heart failure or uncontrolled angina
pectoris; prior myocardial infarction within 6 months of start of chemotherapy;
uncontrolled severe hypertension (failure of diastolic blood pressure to fall below
90 mm Hg despite the use of ≥ 3 anti-hypertensive drugs) or arrhythmias; instable
diabetes mellitus, ulceration from diabetes mellitus or other conditions not allowing
high dose corticosteroids; effusions in pericardium, pleura or abdomen symptomatic
and in need of being punctured.

- Known hypersensitivity to any of the components in the temsirolimus infusion or other
medical reasons for not being able to receive adequate premedication (antihistamine
agents).

- Legal incapacity or limited legal capacity

- Medical or psychological conditions that would not permit the patient to

- complete the study or sign informed consent.

Inclusion Criteria Phase II Part, Chemotherapy Period:

- Adult males ≥ 18 years of age.

- Patients with CRPC defined as confirmed rise of PSA levels after orchiectomy or LHRH
agonist based therapy

- Progressive disease, defined as PSA progression by confirmed rising PSA levels

- PSA at time of study entry ≥ 2ng/ml within 1 week prior to treatment (according to
Scher 2008).

- Bone metastasis and/or lymph node and/or visceral organ metastases allowed.
Measurable and non measurable disease allowed.

- Performance status (PS) 0-1 ECOG.

- Signed written informed consent.

- White blood cell count (WBC) ≥4x10^9/L with neutrophils ≥1.5x10^9/L, platelet count
≥100x10^9/L, hemoglobin ≥9g/dL.

- Total bilirubin <= 2 x upper limit of normal.

- AST and ALT <=2.5 x upper limit of normal, or <=5 x upper limit of normal in case of
liver metastases.

- Serum creatinine <=1.5 x upper limit of normal or creatinine clearance >60 ml/min.

- Androgen ablation will have to be continued. Antiandrogens such as bicalutamide will
have to be discontinued at least 4 weeks prior to the start of study treatment.

Exclusion Criteria Phase II Part, Chemotherapy Period:

- Prior Chemotherapy.

- Clinically symptomatic brain or meningeal metastasis.

- Receiving known strong CYP3A4 isoenzyme inhibitors and/or inducers.

- Any investigational drug within the 30 days before inclusion.

- Not recovered from prior biopsy, surgery, traumatic injury, and/or radiation therapy,
as judged by the investigator.

- Nonhealing wound or ulcer.

- Grade ≥ 3 hemorrhage within the past month.

- Any condition / concomitant disease not allowing chemotherapy with docetaxel,
prednisone and temsirolimus in the discretion of the treating physician, like: Renal
insufficiency requiring dialyses; congestive heart failure or uncontrolled angina
pectoris; prior myocardial infarction within 6 months of start of chemotherapy;
uncontrolled severe hypertension (failure of diastolic blood pressure to fall below
90 mm Hg despite the use of ≥ 3 anti-hypertensive drugs) or arrhythmias; instable
diabetes mellitus, ulceration from diabetes mellitus or other conditions not allowing
high dose corticosteroids; effusions in pericardium, pleura or abdomen symptomatic
and in need of being punctured.

- Known hypersensitivity to any of the components in the temsirolimus infusion or other
medical reasons for not being able to receive adequate premedication (antihistamine
agents).

- Legal incapacity or limited legal capacity.

- Medical or psychological conditions that would not permit the patient to complete the
study or sign informed consent.

Inclusion Criteria Phase II Part, Maintenance Period:

- Completed 8 cycles (up to 26 weeks) treatment in Arm A

- White blood cell count (WBC) ≥4x10^9/L with neutrophils ≥1.5x10^9/L, platelet count
≥100x10^9/L, hemoglobin ≥9g/dL.

- Total bilirubin <=2 x upper limit of normal.

- AST and ALT <=2.5 x upper limit of normal, or <=5 x upper limit of normal in case of
liver metastases.

- Serum creatinine <=1.5 x upper limit of normal or creatinine clearance >60 ml/min.

- General condition sufficient to allow therapy with temsirolimus.

- Signed Informed Consent.

Exclusion Criteria Phase II Part, Maintenance Period:

- Disease Progression in the first 8 cycles (up to 26 weeks).