The Phase 1/2 study is an open-labeled dose-escalating phase I/IIa study of UV1 peptide vaccination in patients with androgen-sensitive metastatic prostate cancer. Patients will be prospectively enrolled in this study if diagnosis of adenocarcinoma only has been histologically confirmed and they are eligible for (or have already started up to 6 months prior to inclusion) standard GnRH-agonist first-line androgen deprivation therapy (ADT) combined with anti-androgen to achieve complete androgen blockade (CAB). UV1 vaccinations will be applied simultaneously with CAB.

When indicated, patients may receive concomitant radiotherapy.

The following 2-step design will be used:

Conventional dose escalation with at least 3 patients per dose level (3 selected dose levels).

Expansion of each dose level to a total of 7 patients for assessment of immune response levels

13 UV1 vaccinations will be given during the first 6 months (week 26) of treatment unless clinical deterioration or unacceptable toxicity is encountered. GM-CSF (Leukine ®) will be administered locally 10-15 minutes before each UV1 vaccination.

Hormone naïve patients will receive standard complete androgen blockade by GnRH-agonist (3 months depot formulation sc.) and bicalutamide 50 mg orally per day (CAB). Patients already on GnRH-agonist therapy will continue with their initial treatment with addition of bicalutamide 50 mg orally per day.