A Phase II Study of Docetaxel Plus Carboplatin in Chemonaive Hormone-Refractory Prostate Cancer (HRPC) Patients

Docetaxel-prednisolone is the current standard in HRPC, based on 2 large randomized trials showing improved survival compared to mitoxantrone-prednisolone. Carboplatin has activity in prostate cancer and the combination of Docetaxel-carboplatin is known to be synergistic and is used with good effect in many cancers. The advantage of using this combination in prostate cancer is suported by clinical data: high response rates of docetaxel-carboplatin-estramustine (with G-CSF support) in a phase II trial (Oh, Halabi, Kelly et al. Cancer. 2003 Dec 15;98(12):2592-8), and additional effect of this combination in prior taxane failures (Oh, George, Tay. Clin Prostate Cancer. 2005 Jun;4(1):61-4). Carboplatin itself has activity and theoretically could target the more hormone resistant clones or neuroendocrine components of the tumor.(Di Sant' Agnese. J Urol. 1994 Nov;152(5 Pt 2):1927-31.) We are studying the combination of docetaxel-carboplatin both given in a weekly, low-dose fashion, without estramustine and without G-CSF. This is expected to be an effective and tolerable treatment for HRPC patients. We will be documenting (to our knowledge) for the first time in this trial the efficacy of the combination given in this particular dose and schedule.

Inclusion criteria

• Histologically confirmed adenocarcinoma of the prostate.
• At the time of enrollment, patients must have evidence of metastatic disease, with either measurable disease per RECIST criteria or non- measurable disease (i.e. positive bones scan) and PSA > 5 ng/mm3.
• Disease progression following androgen deprivation therapy.
• Progression is defined according to the PSA Working Group criteria (see 6.1.3 and 6.3).
• Serum testosterone levels < 50 ng/mm3 (unless surgically castrate). Patients must continue androgen deprivation with an LHRH analogue if they have not undergone orchiectomy.
• No use of an antiandrogen for at least 4 weeks.
• Have not been treated with chemotherapy before.
• ECOG performance status of <= 2.
• Laboratory criteria for entry:

• White blood cell (WBC) => 3000/mm3
• Platelets => 100,000/mm3
• AST < 2.5 x upper limit of normal
• Calculated CCT of => 40 ml/min
• Signed informed consent form.
• Age: 30 years old and above

Exclusion criteria

• Significant peripheral neuropathy defined as grade 2 or higher.
• Within 4 weeks since completing external beam radiotherapy or 8 weeks since completing radiopharmaceutical therapy (strontium, samarium).
• Concomitant chemotherapy or investigational agents.