Patients receive gemcitabine IV over 80 minutes on days 1, 8, and 15 and paricalcitol IV over 15 minutes on days 7 and 14 in course 1. Beginning in course 2, patients receive paricalcitol IV over 15 minutes on days 1, 8, and 15 and gemcitabine IV over 80 minutes on days 2, 9, and 16. Courses repeat every 4 weeks in the absence of disease progression or unacceptable toxicity.