This is an open-label phase I/II study evaluating the addition of ebastine to docetaxel in the treatment for metastatic castration resistant prostate cancer.

Patients will be randomized in a 2:1 fashion to receive ebastine daily during and after treatment with a maximum of 10 courses of docetaxel.

The primary endpoint is change in the profile of urinary and blood lipids to indicate absorption and possible efficacy of ebastine.

Secondary endpoints include PSA response and radiologic progression free survival.

The complete study protocol can be studied by contacting the authors.

Inclusion Criteria:

• 1. Have a histologically confirmed adenocarcinoma or poorly differentiated carcinoma of the prostate (carcinomas with pure small-cell histology or pure high grade neuroendocrine histology are excluded; neuroendocrine differentiation is allowed).

  2. Surgically or medically castrated, with serum testosterone levels of ≤ 50 ng/dL equivalent to 1.7 nmol/L. For patients, currently being treated with luteinizing hormone-releasing hormone (LHRH) agonists, i.e., patients who have not undergone an orchiectomy, therapy must be continued throughout the study.

  3. Have evidence of disease progression after prior therapy for mCRPC:

Disease progression after initiation of most recent therapy is based on any of the following criteria:

• Rise in PSA: a minimum of 2 consecutive rising levels, with an interval of ≥ 1 week between each determination. The most recent screening measurement must have been ≥ 2 ng/mL

• Transaxial imaging: new or progressive soft tissue masses on CT or MRI scans as defined by RECIST 1.1

• Radionuclide bone scan: at least 2 new metastatic lesions 4. Signed informed consent obtained prior to initiation of any study-specific procedures or treatment 5. Age ≥ 18 years 6. Life expectancy ≥ 3 months 7. Performance status 0 - 1 8. Adequate organ functions

  1. Hematological: absolute neutrophil count (ANC) >1.5 x 109/L, platelet count >100 x 109/L, hemoglobin > 6,2 mmol/L

  2. Hepatic: Bilirubin within normal range, aspartate transaminase (AST) and alanine transaminase (ALT) <2.5 upper normal lever, albumin > 25 g/L

  3. Renal: creatinine clearance >30 mL/min/1.73m2

     Exclusion Criteria:

     - 1. History of significant gastric or small bowel resection, malabsorption syndrome, or other lack of integrity of the upper gastrointestinal tract that may prevent compliance with oral drug administration 2. Presence of any serious concomitant systemic disorders and/or psychiatric condition incompatible with the study (at the investigator's discretion) 3. Presence of any active infection (at the investigator's discretion). 4. Central nervous system (CNS) disease including epilepsy or altered mental status precluding understanding of the informed consent process and/or completion of the necessary study procedures.

     5. Concurrent use of cationic amphiphilic drugs (see appendix A) including over-the-counter medication.

     6. Use of other investigational drug 7. Allergic reaction to any of the included drugs