This study will determine the best doses of docetaxel and lonafarnib when the two anti-cancer agents are used in combination. Patients with tumors for which treatment with docetaxel would be appropriate are eligible. A second part of the study will further examine the effectiveness of the combination treatment in men with prostate cancer.

Inclusion Criteria:

• For Part 1: Subjects may be male or female and must be at least 18 years of age.
• For Part 1: Cancer for which docetaxel treatment is appropriate.
• For Part 1: Docetaxel-naïve
• For Part 2: Subjects must be male and at least 18 years of age.
• For Part 2: Subjects must have adenocarcinoma of the prostate confirmed by histologic/cytologic biopsy.
• For Part 2: Subjects must have progressive, metastatic, AIPC and a PSA of 10 ng/ml or more after hormonal therapy prior to docetaxel treatment. Progressive disease is defined as a consistently increasing serum PSA level within 28 days prior to docetaxel administration.
• Adequate organ function within 3 weeks prior to first study drug administration.
• Performance status (ECOG) is less than or equal to 2.
• Subject understands and agrees to procedures and participation by signing informed consent form.
• Agrees to use medically accepted form of contraception.

Exclusion Criteria:

• Receipt of or need to continue to receive prohibited medications (listed in the protocol) more recently than the washout period (indicated in the protocol).
• Surgery within 3 weeks prior to first study drug administration.
• History within 5 years prior to first study drug administration of another malignancy except adequately treated Stage I/II basal/squamous cell skin cancer.
• Radiation therapy to more than 25% of his/her total bone marrow during life.
• Radiation therapy within 3 weeks prior to first study drug administration.
• Known hypersensitivity to prednisone, docetaxel, polysorbate 80, lonafarnib, or any excipients associated with these medications.
• Known contraindication to steroid use.
• Known leptomeningeal or CNS metastasis.
• Heart, vascular, or seizure disorder (detailed list in the protocol) within 6 months prior to first study drug administration.
• Baseline QTc interval greater than 450 msec.
• Grade 2 or more peripheral neuropathy or drug-related toxicity per CTCAE. Exceptions are noted in the protocol.
• Any clinically significant condition or situation that the investigator thinks would interfere with the study evaluations or subject's participation.
• Subject is part of staff personnel involved in the study.
• Subject has known clinically significant immunosuppression.