Preliminary data from a pivotal Phase 2 clinical trial of PLX4032 ( RG7204 ) in metastatic melanoma, have shown significant tumor shrinkage in the majority of patients. These results support previously reported positive data.
PLX4032 is a novel, oral drug that targets a key oncogenic driver in melanoma and other cancers.
The phase 2 ( BRIM2 ) trial is a single-arm study of previously treated metastatic melanoma patients with the BRAF V600 mutation. Primary endpoints for this study are best overall response rate assessed by an independent review committee ( IRC ) using RECIST criteria, and secondary endpoints are best overall response rate assessed by clinical investigators, duration of response, progression-free survival, overall survival and safety. In pivotal studies, independent review committees are used to review and confirm CT scans, including a second follow-up scan and tumor assessments, allowing a patients response to be characterized as confirmed.
The open-label, multicenter study enrolled 132 patients. As of September 27, 2010, data showed a confirmed response rate of 52 percent, including: 3 confirmed complete responses ( CR ) ( no evidence of disease ); 66 confirmed partial responses ( PR ) ( tumor shrinkage of at least 30 percent ).
In addition, 39 patients had stable disease. The median progression-free survival ( PFS ) was 6.2 months, compared to historical PFS of less than 2 months. The median duration of response was 6.8 months. Median overall survival has not yet been reached.
The unconfirmed response rate in the Phase 2 study was 68 percent, further indicating these data are consistent with the data previously reported from the Phase 1 extension study.
The most common drug-related adverse events were rash, photosensitivity, hair loss and joint pain. These were predominantly mild or moderate in severity. Twenty-six percent of patients developed cutaneous squamous cell carcinoma, which was typically managed without treatment interruption.
Source: International Melanoma Research Congress of the Society for Melanoma Research ( SMR ), 2010
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