Interleukin-2 Based Home Therapy of Metastatic Renal Cell Carcinoma: Risks and Benefits in 215 Consecutive Single Institution Patients

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Abstract
In 215 consecutive patients with advanced metastatic renal cell carcinoma seen at a single institution the efficacy and tolerance of different subcutaneous recombinant interleukin-2 based home therapies were assessed. Treatment consisted of subcutaneous recombinant interleukin-2 alone and subcutaneous recombinant interleukin-2 in combination with recombinant interferon-alpha 2 with or without intravenous 5-fluorouracil. Overall objective response rate in 215 patients was 33% (95% confidence interval 26 to 39%). Among 16 patients receiving recombinant interleukin-2 alone there was 1 partial remission (overall response 6%). In 79 patients receiving recombinant interleukin-2 and interferon-alpha 2 in combination 6 complete and 16 partial remissions occurred (overall response 28%). Of 120 patients receiving a combination of recombinant interleukin-2, recombinant interferon-alpha 2 and 5-fluorouracil 13 achieved a complete and 34 a partial remission (overall response 39%). Of all patients 5% achieved long-lasting remissions and remain disease-free. Multivariate analyses identified pretreatment erythrocyte sedimentation rate greater than 70 mm. per hour and lactic dehydrogenase greater than 280 units per l. as independent prognostic factors of major significance (p < or = 0.0001) in metastatic renal cell carcinoma. Additionally, neutrophil count greater than 6,000/microliters., hemoglobin less than 100 gm./l., extrapulmonary metastases and bone lesions were identified as minor (p < or = 0.006) prognostic variables. Patients were assigned to 1 of 3 risk categories according to cumulative risk score defined as the function of the sum of all 6 independent variables. In 116 intermediate risk patients 2-year survival was 65% (median survival not reached after 32 months) with recombinant interleukin-2, recombinant interferon-alpha 2 and 5-fluorouracil, as opposed to 27% 2-year survival (median survival 15 months) with recombinant interleukin-2 and interferon-alpha 2 (p < 0.0001), and 0% (median survival 4.8 months) with single agent recombinant interleukin-2. In the majority of patients systemic toxicity of subcutaneous recombinant interleukin-2 based protocols was limited to grade 1 or 2 constitutional symptoms, that is fever, chills, malaise and anorexia, which allowed for outpatient therapy. The present outpatient recombinant interleukin-2 triple drug combination protocol was as effective as the most aggressive intravenous recombinant interleukin-2 regimen available. Combination home therapy eliminated the need for inpatient and/or intensive care as required for intravenous cytokine administration and, thereby, it substantially improved the therapeutic index and cost-effectiveness of recombinant interleukin-2 therapy in metastatic renal cell carcinoma stratified for risk.