High-Dose Bolus Interleukin-2: Correlating Response Rate with Number of Doses Received

Purpose: The administration of high-dose interleukin-2 (IL-2) in metastatic renal cell carcinoma and metastatic melanoma has led to higher response and survival rates when compared to low dose and subcutaneous administration. In patients who achieve a response, some are complete responses, but at the expense of toxicity. It is of interest to correlate response rate with the number of doses or cumulative dose received. The primary objective of this study is to determine if there is a direct relationship with response and cumulative dose or the total number of doses received.

Methods: A retrospective chart review was conducted of all patients at H. Lee Moffitt Cancer Center diagnosed with metastatic renal cell carcinoma or metastatic melanoma who received high dose IL-2 from September 30^th, 1999 to September 30^th, 2010. The cumulative dose and the number of doses of IL-2 received was recorded and associated with response (complete response, partial response, stable disease or progressive disease). Pertinent data was also collected to determine the incidence of toxicity.

Results: In the metastatic renal cell carcinoma population, 31 out of 55 patients analyzed achieved a response to IL-2. Patients who received a higher number of doses and higher cumulative dose were more likely to respond (p=0.0272 and p=0.0077, respectively). In the metastatic melanoma population, 18 out of 57 patients analyzed achieved a response. Patients who received a higher number of doses and higher cumulative dose were more likely to respond to therapy (p=0.0013 and p=0.007, respectively).

Conclusion: Cumulative dose and number of doses received are associated with a statistically significant difference in response rate.