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Study: Gene therapy improves Parkinson’s symptoms


3 Star


Study: Gene therapy improves Parkinson’s symptoms

Our Review Summary

Room for improvement:

  • Some discussion of costs. While the gene therapy is in the early stages of development and a price is not likely available at the moment, the cost of other non-drug treatments could have been included.
  • There were some critical gaps in the evaluation of the evidence and the reporting was not entirely accurate.
  • More complete discussion of harms.



Why This Matters

Medication can be very effective for reducing the symptoms of Parkinson’s disease, especially in the first few years after onset. However, Parkinson’s is a progressive disorder that can eventually cause significant disability in a significant number of sufferers. Deep brain stimulation (DBS) has been used for almost two decades for people who no longer benefit from drug therapy. Although DBS provides relief of symptoms for many, it is not a panacea. The kind of experimental gene therapy discussed in this story could eventually provide another option to help patients manage their symptoms.


Does the story adequately discuss the costs of the intervention?

Not Satisfactory

We would have liked to have seen some mention of costs. While the gene therapy is in the early stages of development and a price is not likely available at the moment, the cost of other non-drug treatments could have been included. For example, deep brain stimulation costs approximately $30,000 per side of the brain affected as is covered by many insurers. This information would provide readers with some perspective on costs.

Does the story adequately quantify the benefits of the treatment/test/product/procedure?

Not Satisfactory

The story relays the primary outcome in appropriate statistical terms when it says, “After six months, those who got the gene therapy scored 23 percent better on a standard test to measure motor skills while those who got the sham operation did about 13 percent better.” However, the story gets carried away in the last paragraph when it describes the anecdotal benefit of a single patient who goes from being nearly frozen to playing jazz music.  Although the treatment was “like a miracle” for this patient, the magnitude of the benefit seen in the study was clinically quite small and not consistent with this description. There was also no reporting on the secondary outcomes, which included measures that assess quality of life and how well a patient is able to function. The treatment seemed to improve some of these measures, but not others.  

Does the story adequately explain/quantify the harms of the intervention?

Not Satisfactory

Any discussion of an experimental procedure deserves comments on the potential and actual harms of the treatment. This is perhaps especially true for viral vector gene therapies that requires burring a hole in the skull and injecting precisely into the brain. To its credit, the story says that we don’t know if there might be any long-term damage from introducing viruses into the brain. However, it also should have mentioned that the treated patients in this study had more headaches and nausea than the sham surgery group (although these problems were described as mild to moderate and had resolved by the end of the study).

Does the story seem to grasp the quality of the evidence?

Not Satisfactory

This was a carefully conducted study and the story’s coverage of it was fairly detailed considering the relatively short length. The description of the sham surgery was particularly good. Nevertheless, there were some critical gaps and the reporting was not entirely accurate. The story states, “Kaplitt and colleagues tested the gene therapy on 16 people while 21 others received a sham surgery.” That is actually not the case. A total of 22 patients were enrolled to receive the gene treatment and 16 were evaluable at the 6 month time period. This compares to 23 enrolled in the sham procedure with 21 evaluable. That’s a 27% drop out rate for the gene therapy group compared with only 9% for the sham surgery. And while the story notes that one of the limitations is a lack of longer-term data on how these patients fare, it doesn’t comment on the difficulty of generalizing results from such a small study to the larger population of Parkinson’s patients. Lastly, given the issues of observer and subject bias, we think that some comment on the blinding of the study would have been appropriate.

Does the story commit disease-mongering?


There was no disease-mongering in this story.

Does the story use independent sources and identify conflicts of interest?


The story quotes an independent expert with a research and advocacy group. The story also discloses that the study was paid for by the drug’s developer, Neurologix, and that the researchers have financial ties to the company and other pharmaceutical companies.

Does the story compare the new approach with existing alternatives?


The story noted that it is unclear whether the new treatment is as effective as another surgical technique, deep brain stimulation.

Does the story establish the availability of the treatment/test/product/procedure?


The lead sentence called the new treatment “experimental” and the study a “mid-stage test,” so we think readers will understand that this surgery is not currently available to the average patient. Given the early stage of the research, the story is probably a tad overoptimistic when it quotes one researcher saying, “We are getting much closer to a reality where this treatment can be offered to patients.” While this is true, the treatment still has many hurdles to clear before it can be widely used.

Does the story establish the true novelty of the approach?


The story says that this is the first time a gene therapy for Parkinson’s disease has shown positive results in a placebo-controlled study. This is accurate, and the therapy does seem to be quite novel. It would have been informative to note that other gene therapies have been shown to be beneficial in open label trials and failed in randomized trials as compared to placebo. A previous attempt to demonstrate the value of another gene therapy for Parkinson’s failed in large measure due to problems with the study design.

Does the story appear to rely solely or largely on a news release?


This story was not based on a news release

Total Score: 6 of 10 Satisfactory


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