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Posted June 10, 2013: by Bill Sardi
Mindless medical reporting is rampant in the news media. Biology-trained writers exercise no scrutiny over press releases issued by industry or public health authorities. The public pays the price. A recent example is a news report that says a new drug may avert the need for double mastectomies among breast cancer patients.
In the wake of the disclosure by actress Angelina Jolie that she underwent double-sided mastectomy (removal of both breasts) due to her genetic propensity to develop breast cancer decades in her future, a pharmaceutical company has announced it is pursuing a “breakthrough” to “tackle a faulty gene” that causes this type of cancer. The drug proposes to eliminate the need for double mastectomies. Initial tests conducted among 70 patients produced “impressive responses” to the drug, called BMN673, a drug that targets the BRCA gene.
BMN673 exhibits potent anti-tumor action by inhibition of an enzyme called PARP.
Should women hold their breath now in eager anticipation of this drug?
PARP inhibitors have been proposed as anti-cancer agents since 2005. PARP (Poly ADP-ribose polymerase) is an enzyme responsible for DNA breaks in the BRCA gene involved in some forms of breast cancer. Graphic presentation of how PARP inhibitors work can be found online.
In 2006 researchers claimed that PARP inhibitors are “the long-sought” drugs that specifically address BRCA gene mutations associated with breast cancer. By 2009 researchers claimed PART inhibitors “are extremely well tolerated” in early human studies.
But wait, PARP is essential for repair of single-strand DNA breaks. Inhibiting this repair enzyme would be deleterious, would it not? Inhibit PARP and more gene mutations would result!
Well yes, but modern medicine has a way of turning the biology to suit drug companies. If PARP is inhibited, then radiation treatment works better!
Radiation can damage and kill off more breast cancer cells if combined with PARP inhibitors. The idea is to encourage breaks in the DNA of BRCA genes so that cancer cells die off more readily. But by 2011 this idea was being challenged.
In 2010 a number of PARP inhibiting drugs were undergoing human clinical trials and third generation PARP inhibitors were being used. But if the first-generation PARP inhibitors were safe, why would there be a need for third-generation versions of these drugs?
By 2012 researchers began reporting some “hurdles” with PARP inhibitor drugs including treatment resistance. Then in 2013 investigators report that “a more refined approach” is needed to identify “the unique subset of patients that would most benefit” from PARP inhibitors.
In other words, if this were a breakthrough, it would be limited to a small number of patients. Oncologists have difficulty finding patients who will respond to PARP inhibitors. As it is, BRCA gene mutations only comprise 5-10% of breast cancers.
A number of natural PARP inhibitors have been identified. Among them is vitamin D, a ten-cent vitamin. No natural PARP inhibitors have entered human clinical trials, even though, if successful, would reduce treatment costs significantly. © 2013 Bill Sardi, Knowledge of Health, Inc.
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