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Potential new kidney cancer drug said to be “more effective than standard of care,” but only if you’re a mouse

New HIF-2 kidney cancer therapy more effective than current treatment, study shows

Our Review Summary

Kidney CancerThis is a mouse study of a product called PT2399 from a class of drugs called HIF-2 inhibitors that have purportedly been shown to be “more effective and better tolerated than the standard of care drug” in the treatment of kidney cancer. While this is promising research, appropriate language to say that this is a very small, very preliminary and non-definitive rodent study was largely missing. A novel compound can be very exciting for the researchers, those who are making and promoting it, and the institution that has a financial interest in its success, but that excitement needs to be tempered with a ‘reality check’ on the challenges of translating animal research to human outcomes. from observers unconnected to the research.  Without that, the news release reads as a mere PR exercise, designed to generate premature (yet possibly unfounded) excitement.

[Editor’s note: The news release says, “In the study in Nature, investigators show that HIF-2 inhibition was able to control metastatic kidney cancer even after 7 lines of prior therapy. See video.”  However, the release contained no link to the video so the review was completed without viewing the video.]


Why This Matters

If it is true that nearly 400,000 Americans are currently diagnosed with kidney cancer, and it produces an additional 60,000 new cases each year (according to the National Cancer Institute) then this research could be of a very large public health importance. Unfortunately, this release doesn’t discuss the effectiveness and problems with current treatment in humans.

The study’s key findings that the “HIF-2 inhibitor was more active than sunitinib and that it was active against tumors progressing on sunitinib” as well as being “better tolerated” could be a real advance if such advantages are later shown to be seen in people. The key bit of missing information is that mice that gain weight on the drug (when the comparator mice were “sickly and lost weight”) are still mice, and no amount of tweaking of these results will magically transform results that are directly applicable in humans.

Even if new biomarkers are identified that determine which mice would be most likely to benefit from HIF-2 therapies, we may be decades away from having a compound that is proven to work in humans. Sometimes rodent research can be terribly hopeful, and described in hyperbolic terms, but turn out later not to be terribly helpful. Institutions that present animal research as applicable to humans run the risk of raising false hopes in desperate patients.


Does the news release adequately discuss the costs of the intervention?

Not Satisfactory

No costs mentioned. If a release claims that a drug is “more effective and better tolerated than the standard of care drug,” it should also be prepared to give some cost specifics.

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

Not Satisfactory

We are told that “mice transplanted with kidney cancer from over 20 patients” found that “the HIF-2 inhibitor PT2399 controlled cancer in half of the tumors.”  This is unsatisfactory on a number of levels. How many mice?  How well did the comparator mice do?  What does “controlled cancer” mean?  Were the differences statistically or clinically meaningful?  These are, admittedly awkward questions, but the kind of questions that need to be explained in a press release that claims “New HIF-2 kidney cancer therapy more effective than current treatment, study shows.”

Does the news release adequately explain/quantify the harms of the intervention?

Not Satisfactory

Other than explaining that some of the kidney cancers were ‘resistant’ to the drug’s effects, we learn nothing about the potential adverse effects of the new treatment.

While “mice on sunitinib were sickly and lost weight,” the mice on the new drug gained weight, according to the release. That is hardly sufficient information to know whether the new treatment was well tolerated. Perhaps weight gain was due to fluid retention.

Does the news release seem to grasp the quality of the evidence?

Not Satisfactory

The biggest problem with the quality of the evidence is that there were no caveats or cautions about the research’s applicability to humans.  We’d like news releases to be more honest in this regard: if this is very preliminary, and very tentative research, it could still be newsworthy, but please say so.

Does the news release commit disease-mongering?


No obvious disease mongering.

Does the news release identify funding sources & disclose conflicts of interest?


The news release was particularly fulsome in explaining the multiple, overlapping conflicts of the researchers, the sponsoring pharmaceutical company and the academic institution that has a financial stake in this discovery. Well done.

Does the news release compare the new approach with existing alternatives?

Not Satisfactory

While the treatment was compared to another kidney cancer drug, sunitinib, we don’t really learn what other alternative treatments outside of sunitinib or PT2399 are used to treat kidney cancer.

Does the news release establish the availability of the treatment/test/product/procedure?


It’s pretty clear this is an experimental drug, so experimental it doesn’t even have a name, just a codename: PT2399.

Does the news release establish the true novelty of the approach?


It is pretty clear this is a novel approach, and we do get some explanation of why HIF-2 may have been disregarded in the past.

Does the news release include unjustifiable, sensational language, including in the quotes of researchers?


While the headline and lead sentences are overt exaggerations, we’ve dealt with that issue elsewhere in the review. The release doesn’t otherwise rely heavily on sensationalist terms so we rate it satisfactory. As mentioned above, there is a potential that some patients might be given false hope from the release if they are unfamiliar with the long trial process ahead.

Total Score: 5 of 10 Satisfactory


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