PRIOR CONCURRENT THERAPY: Biologic therapy: At least 4 weeks since prior biologic therapy or immunotherapy No concurrent immunotherapy No colony-stimulating factors during first course of therapy Chemotherapy: No prior chemotherapy except radiosensitizing agents used in adjuvant setting or in treatment of locally advanced disease No prior gemcitabine No prior ISIS 2503 No other concurrent chemotherapy Endocrine therapy: Not specified Radiotherapy: No prior radiotherapy to 25% or greater of bone marrow No concurrent radiotherapy Surgery: Not specified