ZymoGenetics: preliminary data for IL-21 in metastatic melanoma, renal cell cancer show antitumor activity

By E. Janene Geiss

Philadelphia, June 5 - ZymoGenetics, Inc. said Monday that findings from a completed phase 1 clinical trial with Interleukin 21 in patients with stage IV metastatic melanoma and renal cell carcinoma showed a satisfactory toxicity profile and preliminary evidence of antitumor activity.

The open-label phase 1 clinical trial was a two-part study. The first part evaluated dose escalation to determine maximum tolerated dose and the second part studied safety and tolerability at the dose level identified in the first half of the study, according to a company news release.

The results were focused on 34 patients treated at the recommended dose of 30 mcg/kg, six of whom were treated in the first part of the study. Overall, there were 18 metastatic melanoma and 16 renal cell carcinoma patients treated at the recommended dose.

Patients were given two cycles of five consecutive daily doses of IL-21 with an intervening rest period. Nine patients received additional cycles of IL-21. IL-21 administration was associated with increases in the lymphocyte activation marker soluble CD25 and decreases in lymphocyte counts demonstrating clear pharmacologic effect on the immune system, officials said.

The safety profile of IL-21 observed in the second half of the study (dose of 30 mcg/kg) was similar to that of the first part, with three subjects experiencing Grade 3 adverse events related to IL-21 (abdominal pain, thrombocytopenia and hypophosphatemia).

Evidence of antitumor activity was assessed by the Recist criteria and revealed that in the second part of the study, one renal cell carcinoma patient achieved a partial response and one metastatic melanoma patient had a complete response.

The results were presented at the American Society of Clinical Oncology annual meeting in Atlanta.

Overall, the studies showed that IL-21 is an active cytokine that can be administered in an outpatient regimen, and the available clinical data support further clinical investigation of IL-21 as a new therapeutic agent for the treatment of cancer.

ZymoGenetics said it is planning to start phase 1/ 2 testing of IL-21 for renal cell carcinoma in combination with tyrosine kinase inhibitors in the second half of 2006.

The company also said it expects to begin a study shortly combining IL-21 with rituximab in patients with non-Hodgkin's lymphoma.

ZymoGenetics is a Seattle biopharmaceutical company.

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