Are We at the End of a Long, Murky Slog in Cancer Treatment?
November 4th, 2011
Posted by Patti Doherty, R.N.
For many years, a lot of people (including us) have called for a new way to look at, diagnose, and treat cancer. This means changing everything – from how we classify cancer to research strategies to treatment regimens. It’s been a long slog, through murky data and lots of failures, but now we’re finally seeing targeted treatments, matched with diagnoses to select the right niche of patients. Best of all, there is strong evidence to suggest that those treatments may work very well in those patient cohorts.
These are unlike most current cancer therapies, which are marked by “broad brush” descriptions (“a breast cancer drug”) and expensive price tags that can wipe out savings, burden insurance companies, and may have little benefit. But the FDA has just approved a series of treatments (albeit for rarer and later-stage cancers) that come with companion diagnostics to make sure the patient is the right one (i.e., has the right biomarker profile) for that drug. Identification of these patients prior to treatment means that while the treatments are still very costly, they stand a much better chance of actually working.
Just recently, the FDA approved (under its fast-track NDA approval system):
Zelboraf: indicated to treat metastatic or unresectable melanoma in about half of melanoma patients whose tumors have the V600E mutation in the BRAF gene. Clinical trials showed improvement in survival compared to other chemotherapies. The companion diagnostic test (cobas 4800 BRAF V600 Mutation Test) costs just $150. The drug cost? $56,400 for six months. The good news? The majority of patients taking Zelboraf in the pivotal clinical trial are still alive.
Adcetris: designed to treat progressive Hodgkin’s lymphoma (HL) and anaplastic large-cell lymphoma (ALCL) by targeting chemotherapy doses to cells that carry a CD30 marker and bypassing healthy cells. In the HL group, complete or partial shrinkage of the cancer was achieved in 73 percent of the patients who on average responded to therapy for 6.7 months. The endpoint in the ALCL group of patients was similar to the HL group and 86 percent achieved complete or partial response on average for up to 12.6 months.
Xalkori: to treat a small subset of late-stage patients with non-small cell lung cancer (NSCLC) whose cells express the abnormal anaplastic lymphoma (ALK) protein. In two multi-center clinical trials, complete or partial shrinkage of the cancer was achieved in 50 percent of patients with a median response of 42 weeks and 61 percent with a median response rate of 48 weeks. The drug was developed by Pfizer and costs $115,200 per year, and the Vysis ALK Break Apart FISH Probe Kit (Abbott) is the companion diagnostic at a cost of $250.
A reduction in the time to approval is a side benefit to the strategies put forth by the drug and diagnostic companies pairing drugs with companion diagnostics – and will likely stimulate more pairing of drugs and diagnostics in the near future. As an added plus, linking diagnostics with treatments will pinpoint who’s qualified for the drug – and insurance carriers may then rejoice in the cost savings from providing coverage to only those patients who could benefit. And, though many other patients with life-threatening cancers won’t qualify, drug developers will be able to turn their attention to looking for treatments for those non-responders.
Nonetheless, enough questions remain to create more than a little residual murkiness. Do we (or could we) know enough about enough biomarkers to make this strategy effective for more cancers? What happens when tests are developed to disqualify patients? What if biomarker tests are positive, but don’t point confidently to a certain cancer? What if a patient has several cancers, or has a cancer that has metastasized? Share your thoughts with us here.
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