Inclusion Criteria:

1. ECOG 0 - 2

2. Histologically proven adenocarcinoma of the prostate.

3. Patients with CRPC (castration resistant prostate cancer): advanced or metastatic
adenocarcinoma of the prostate.

4. Prior treatment with a GnRH-agonist or GnRH-antagonist for at least 6 months. The
medication must not have been changed for at least 3 months prior to start of study
treatment.

5. Prior treatment with an anti-androgen (e.g. bicalutamide, flutamide,
cyproteronacetate) is allowed but not necessary. Patients treated with anti-androgen
must have discontinued anti-androgen for at least 6 weeks prior to start of study
treatment.

1. Dose escalation part only: prior treatment with an anti-androgen and GnRH
agonist or antagonist is allowed.

2. Dose expansion part only: prior concomitant treatment with an anti-androgen and
GnRH agonist or GnRH antagonist for ≤6 weeks is allowed (in order to control
flare up).

6. Serum testosterone within castration level (<50 ng/dl or < 1,7 nM)

7. Disease progression demonstrated by a rising PSA with or without metastases. PSA ≥2
ng/mL at study entry. Rising PSA is defined as two consecutive rises over a nadir
value; the individual measurements are obtained at least 1 week apart.

Exclusion criteria:

1. Dose expansion part only: Secondary hormonal manipulation of prostate cancer (other
than GnRH agonist or antagonist) for more than 6 weeks, including concomitant
anti-androgens.

2. Prior cytotoxic therapy e.g. with docetaxel, mitoxantrone.

3. Patients who have received radiotherapy of target lesions. Patients who have received
local radiotherapy of non-target lesions for local symptom control within the last 4
weeks must have recovered from any adverse effects of radiotherapy before recording
baseline symptoms. Lesions treated with locoregional therapies within the last 3
months before study inclusion do not qualify as target lesions.

Additional protocol-defined inclusion/exclusion criteria apply.