Vemurafenib is a small molecule orally active and drawn so as to selectively inhibit the mutated protein BRAF. BRAF [V-raf murine sarcoma viral oncogene homolog B1] is a human gene that encodes for a protein called B-RAF, which is involved in the signals that regulate the cell cycle and growth. In many tumors this gene can be mutated and this causes a change of the protein B-RAF. This mutation can increase the growth and spread of cancer cells. A mutation of the BRAF gene occurs in approximately 60 percent of melanomas and 8 percent of all solid tumors. The use of vemurafenib (RG7204, PLX4032) seems significantly better, compared to chemotherapy, the overall survival in patients with metastatic melanoma positive for the BRAF V600 mutation, previously untreated. In the study, it was found that the risk of death is decreased by 63% for people administered with vemurafenib compared to those treated with chemotherapy. Furthermore, vemurafenib has reduced significantly, up to 9%, the risk of worsening of the disease compared to chemotherapy. The results are extremely encouraging as they have demonstrated in patients who received the new drug a significant improvement in overall survival and progression-free survival compared with patients who received therapy with dacarbazine. The study showed its overall effectiveness, showing a rapidity of action that achieves objective responses in approximately 50% of patients with melanoma with BRAF gene mutation. Moreover, even the initial concerns about possible effects of toxicity skin were overcome as they have proved to be well tolerated. The go-ahead to vemurafenib is based on the results of two studies, BRIM2 (Phase II) BRIM3 (phase III).
The trial BRIM3, conducted in patients not previously treated and published last June in the NEJM, showed that in patients with BRAF V600-positive melanoma, the experimental drug has led to a 63% reduction in the risk of death (hazard ratio [ HR] = 0.37; P <0,0001) and a 74% prolongation of progression-free survival (PFS) compared to standard treatment (HR = 0,26; P <0,0001). Moreover, the analysis of overall survival (OS) at 6 months showed an advantage of 20% in the group treated with the BRAF inhibitor compared to that treated with dacarbazine (84% against 64%). All results reached statistical significance. In addition, the molecule is generally well tolerated and safety data were in line with those that emerged in previous studies on the anti-BRAF.
In BRIM2 study, conducted in patients previously treated, vemurafenib has been shown to reduce the size of the tumor in 52% of patients. In the world the number of diagnosis of melanoma is steadily increasing, it is estimated that at least a hundred thousand new cases a year (about 7 thousand in Italy). The prospects of recovery are greatly improved over the past few decades, largely due to early diagnosis. Today from a tumor discovered with a thickness less than one millimetre it heals in almost all cases. Instead, in front of those cancers discovered at an advanced stage for a long time oncology has remained essentially the pole. At least until now. A monoclonal antibody gave the first jolt, ipilimumab, and now there are also the inhibitors of the BRAF gene mutated while already studying other drugs against