Primary Objectives:

1. To determine the efficacy of combining Interferon Alpha (IFN) with etoposide for the treatment of relapsed osteosarcoma.
2. To determine if IFN alters the plasma pharmacokinetics of etoposide.
3. To determine the toxicities of IFN and etoposide when administered together.
4. To determine IFN blood levels following combination therapy.

Interferon Alpha (IFN)- will be given as a shot under the skin. One hour later, VP-16 will be infused through a catheter (tube) placed in a vein over 3 hours. The drugs will be given daily for 5 days. The treatment will be repeated every 3 - 4 weeks for up to 24 - 32 weeks (8 courses). The catheter will remain in place throughout treatment.

Patients who are candidates for surgery will first receive two courses of treatment. If the tumor gets worse or if severe side effects occur, treatment will be stopped, and the tumor will be removed right away. If the tumor responds well (begins to shrink or does not get worse) and severe side effects do not occur, the patient will receive six more courses of treatment after surgery.

Patients who are not candidates for surgery will receive two initial courses of treatment. If the tumor responds well and severe side effects do not occur, the patient will receive six more courses of treatment.

The treatment will be given in the outpatient department. Before treatment begins, the patient will have a health examination. Blood tests, a urine test, and heart tests will be given. X-rays, computed tomography (CT) scans, and a bone scan will be done. The location and size of all lesions will be recorded.

During treatment, patients will have a blood test every week. Before each course, a health examination, a urine test, and chest x-ray will be given and the size of all measurable cancer will be recorded. After the second course, the CT and bone scans will be repeated. All the tests will be repeated at the end of the study.

About 37 patients will be treated on the study at M. D. Anderson.

THIS IS AN INVESTIGATIONAL STUDY. IFN- and VP-16 are approved by the U.S. Food and Drug Administration for treating some types of cancer. Their use together against osteosarcoma is investigational.

Inclusion Criteria:

1. Patients with histologically confirmed relapsed osteosarcoma who have failed standard chemotherapy.
2. Age 5-70 years.
3. Life expectancy of at least 12 weeks and a Zubrod performance status of less than or equal to 2.
4. Patients must have measurable disease.
5. Adequate hematologic, coagulation, renal, and hepatic function.
6. No chemotherapy, immunotherapy, hormonal therapy or radiation therapy within 3 weeks of study entry.

Exclusion Criteria:

1. Patients who are likely to have significant systems because of rapidly progressive disease, ascites or hepatic metastasis.
2. Pregnant or lactating women.
3. Patients who have had more than one prior biologic response modifier.
4. Serious intercurrent illness, active infections, or central nervous system (CNS) disease.
5. Patients of childbearing potential, not practicing adequate contraception.
6. Significant cardiovascular disease.