14618 Background: Based on the known efficacy of docetaxel (D) in Androgen Independent Prostate Cancer (AIPC), and demonstrated activity of the antiangiogenesis agent thalidomide in combination with docetaxel, a Phase I trial in patients (pts) with AIPC with evidence of progression by unidimensionally measurable disease or rising serum Prostate Specific Antigen (PSA) levels after antiandrogen withdrawal was designed. The study evaluates the combination of escalating doses of D and lenalidomide (Ln), a derivative of thalidomide with immunomodulatory and antiangiogenic properties. Pts were permitted to have no more than two prior chemotherapy regimens. Methods: Pts were given D and Ln on a q3 week dose-escalation schedule. Dose Levels of D (mg/m2): Level (L) 1 = 60 L2-L5 =75, given IVPB over 60 minutes in combination with prednisone 5mg po bid. Decadron 20 mg was given 12, 6 hrs and 15 minutes prior to D on D#1. Dose of Ln (mg/day) on D#1–14 of 21-day cycle: L 1 = 10 mg, L2= 10 mg, L3 = 15 mg, L4–20 mg L5 = 25 mg. Patient Characteristics: L1: N = 5. Median Age 66.2 yrs. Median PSA = 101.9 (range 5.9–164.0). Prior CT: none. Prior palliative RT: none. Patients with unidimensionally measurable disease: 4, all in lymph nodes. Patients with bone metastases: 5. Pre-treatment, 1 patient required narcotic analgesics. Results: Five L1 patients are evaluable for toxicity and response. Median number of cycles administered = 4 (range 2–5). Toxicity: There have been no Grade (G) 3 or 4 toxicities. Anti-tumor activity: Two pts (40%) have had a greater than 50% decline in serum PSA on 2 consecutive measurements at least 2 weeks apart. Of 4 pts with unidimensionally measurable disease, all have stable disease by RECIST criteria. Conclusions: At L1, D + Ln has been well tolerated in AIPC. Further dose escalation to L2 and above is planned. [Table: see text]