Great apparent advance for some melanoma patients. A series in the NY times:
A new kind of cancer therapy, it was tailored to a particular genetic mutation that was driving the disease, and after six years of disappointments his faith in the promise of such a “targeted” approach finally seemed borne out. His collaborators at five other major cancer centers, melanoma clinicians who had tested dozens of potential therapies for their patients with no success, were equally elated.
Once unleashed, however, any cancer seemed to rely on the protein made by a particular mutated gene to fuel its wild growth. In all of the PLX patients, that gene was B-RAF. And whatever the cause, they came to consider themselves, so far as it was possible with what has always been a virtually untreatable cancer, charmed.
In new results from 31 melanoma patients with the BRAF mutation who were treated with 960mg of PLX4032 twice a day, 64% (14) of the 22 patients who could be evaluated so far met the official criteria for partial response (this involves the diameter of tumours shrinking by at least 30% for at least a month). A further six of the 22 patients also showed a response, but, at the time of the congress presentation, it was too early to say whether the tumours would shrink far enough to meet these criteria.
“What makes this treatment different from standard chemotherapy is that standard chemotherapy attacks the machinery involved in cell division; so to stop the cancer cells dividing uncontrollably, most standard chemotherapy aims to block the mechanism of division by interfering directly with DNA replication or with microtubules in the dividing cells. PLX4302 is different because it attacks the genetic programme that is causing the cells to divide uncontrollably, and we think the BRAF mutation is driving that programme. The drug is blocking the genetics of the tumour, rather than trying to interfere with the proliferation of the cells and, as a result, there are fewer side effects, although there are some. We are seeing some pretty dramatic and rapid responses, and they are occurring in sites where we rarely see responses to chemotherapy, such as in the bone.
Medicynical note: Until now melanoma has been refractory to virtually all interventions. This is a real positive step if the responses are durable and life extending–as they seem to be.