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Posts Tagged efficacy

Meet the new drugs, same as the old drugs?

“Targeted therapy.” It’s the holy grail of cancer research these days. If you listen to its most vocal proponents, it’s the path towards “personalized medicine” that improves survival with much lower toxicity. With the advent of the revolution in genomics that has transformed cancer research over the last decade, including the petabytes of sequence and gene expression data that pour out of universities and research institutes, the promise of one day being able to a patient’s tumor, determining the specific derangements in genome and gene expression that drive its uncontrolled proliferation, and finding drugs to target these abnormalities seems more tantalizingly close than ever. Indeed, it seems so close that even dubious practitioners, such as Stanislaw Burzynski, have jumped on the bandwagon, co-opting the terms used by real oncologists and real cancer researchers to sell “personalized gene-targeted cancer therapy,” which in their hands are really no more than a parody of efforts to synthesize the enormous quantity of genomic data each patient’s tumor possesses and figure out how best to take advantage of it, a “personalized genomic therapy for dummies,” if you will.

That’s not to say that there aren’t roadblocks to realizing this vision. The problems to be overcome are substantial, and I’ve discussed them multiple times before. For example, just a couple of weeks ago I discussed an example of just what it takes to apply these new genomic techniques to an individual patient. The resources required are staggering, and, more problematic, there often aren’t any single “magic bullet” molecular pathways identified that can be targeted with existing drugs. The case I discussed was a fortunate man indeed in that such a pathway was identified, but most tumors are driven by many derangements in growth control, metabolism, migration, and the other hallmarks of malignancy described by Robert Weinberg. Worse, in many cases we don’t even have drugs that can attack many of the abnormalities that drive cancer progression. Then there’s the issue of tumor heterogeneity, which comes about because cancer is as good example of a disease as I can think of in which evolution due to natural selection results in incredible differences in the cancer cells in one part of the tumor compared to other parts of the tumor or in the tumor metastases. A “targeted” therapy that targets the genetic abnormalities in one part of the cancer might well fail to target the genetic abnormalities driving another part of the tumor.

These, and many other reasons, are why we haven’t “cured cancer” yet.
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Posted in: Cancer, Clinical Trials

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Don’t Believe The Hype: Cholinesterase Inhibitors As A Treatment For Dementia

Don’t Believe The Hype: Cholinesterase Inhibitors As A Treatment For Dementia
I distinctly remember the day I attended a “drug lunch” (as a PM&R resident in New York City) to learn about the value of donepezil (aricept) for the treatment of dementia. I was astonished by the drug’s lack of efficacy – the graph displayed in the PowerPoint show demonstrated a 2-point improvement on the Mini Mental State Exam (MMSE), an effect that began after 6 months of donepezil use, and persisted for only 6 months after that. A 2-point difference on the MMSE has no clinical relevance of which I’m aware. The drug’s common side effects include: nausea, vomiting, diarrhea, loss of appetite, tiredness, drowsiness, trouble sleeping, or muscle cramps. That day I vowed never to prescribe the drug to my elderly patients.
Nonetheless, I was dumbfounded by the number of patients who came to the hospital already on the medication. Over and over again I heard the same story: “mom is becoming forgetful so our doctor started her on this medication to help her memory.”
When I asked if the family if they thought the medicine helped, the response was equally predictable: a shrug and then “what else can we do?”
Here we have a classic example of a medical problem with no satisfactory treatment or cure – and a desperate desire on the part of patients and family members to do something – anything – about it. Many times people in these predicaments turn to alternative medicines, herbal supplements and faith –based remedies. And sometimes they turn to FDA-approved drugs.
The Cochrane Collaborative has reviewed the scientific literature on the use of cholinesterase inhibitors (like donepezil) in mild dementia, and has found:
There is no evidence to support the use of donepezil for patients with mild cognitive impairment (MCI). The putative benefits are minor, short lived and associated with significant side effects. http://www.cochrane.org/reviews/en/ab006104.html
So how did this drug get approved? Well, there do seem to be some small improvements (of dubious clinical significance in my opinion) in measures of cognitive impairment in patients with Alzheimer’s dementia in particular. http://www.cochrane.org/reviews/en/ab005593.html
AHRQ states:
The evidence is mixed, however, about the effects of cholinesterase inhibitors on functional measures such as instrumental activities of daily living (i.e., ability to use the telephone, mode of transportation, responsibility for medication, and ability to handle finances). In general, the studies show little or no effect on functional decline after 6 months of treatment and a small but statistically significant difference from placebo after 12 months of treatment.
Research has found no clinically important differences between people taking cholinesterase inhibitors and those taking placebo in the development of behavioral and psychological symptoms… Studies rarely addressed other important health outcomes such as utilization of health care services, injuries, and caregiver burden.
http://www.ahrq.gov/clinic/3rduspstf/dementia/dementsum.htm
Pfizer’s press release (when they received FDA approval to market Aricept in 1996) noted:
Alzheimer’s disease is a family tragedy. ARICEPT will benefit patients and families alike by improving or maintaining patient function, which in turn may help ease the burden for caregivers and help maintain personal dignity… “ARICEPT represents a significant step forward in addressing the therapeutic needs of the Alzheimer’s disease community…This therapy will help to change the approach to the management of Alzheimer’s disease.
http://www.pslgroup.com/dg/e2aa.htm
Global sales of Aricept were approximately $1.1 billion for 2008 alone.
Me-too cholinesterase inhibitors have seen similar global profits, with sales of namenda at about $1 billion as well in 2008. http://www.businessweek.com/magazine/content/04_14/b3877629_mz073.htm All this while the AHRQ can find no clinically relevant difference between the drugs in this class, and the effects they have are small and short lived.
There are pharmaceutical innovations that have changed the course of history (imagine where we’d be without the polio or smallpox vaccines), while others leverage the tiniest statistically-significant effects to drive global drug empires driven by public feelings of helplessness in the face of currently incurable diseases.
It’s no wonder that the public has a mistrust of pharma – their marketing engines drive sales of drugs that have vastly different clinical value. That means it’s up to physicians and scientists to tease out the legitimate enthusiasm from the marketing hype. And judging from all the patients with mild dementia that I see on cholinesterase inhibitors, I give us a failing grade.

I distinctly remember the day I attended a “drug lunch” (as a PM&R resident in New York City) to learn about the value of donepezil (Aricept) for the treatment of dementia. I was surprised by the drug’s lack of efficacy – the graph displayed in the PowerPoint show demonstrated a 2-point improvement on the Mini Mental State Exam (MMSE), an effect that began after 6 months of donepezil use, and persisted for only 6 months after that. A 2-point difference on the MMSE has no clinical relevance of which I’m aware. The drug’s common side effects include: nausea, vomiting, diarrhea, loss of appetite, tiredness, drowsiness, trouble sleeping, or muscle cramps. That day I realized that the risk-benefit profile did not support its use.

Nonetheless, I was perplexed by the number of patients who came to the hospital already on the medication. Over and over again I heard the same story: “Mom is becoming forgetful so our doctor started her on this medication to help her memory.” (more…)

Posted in: Pharmaceuticals

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