Combination Chemotherapy Following GM-CSF in Treating Patients With Multiple Myeloma

RATIONALE: Drugs used in chemotherapy use different ways to stop tumor cells from dividing so they stop growing or die. GM-CSF may make cancer cells more sensitive to the effects of chemotherapy. Combining more than one drug with GM-CSF may kill more tumor cells. PURPOSE: Phase II trial to study the effectiveness of combination chemotherapy, consisting of cyclophosphamide plus vincristine, following GM-CSF in treating patients with multiple myeloma that has not responded to previous treatment.