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Expert Commentary
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| By Jane Chin, Ph.D. of Jane Chin Associates on Oct 12 2007 2:50PM |
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| Avastin: It's For Tumors! It's For Eyes! |
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Talk about cannibalizing your own market share; Genentech's Avastin is giving Genentech's Lucentis a run for the money.
And it really is about the money... but not because Genentech wants it that way. Doctors are using Avastin off-label (not approved by the FDA) as a cost strategy over using Lucentis for treating an eye condition called Wet Macular Degeneration.
This is not surprising, because doctors (and pharmacists and even patients) have been working around drug costs for a long time - the old "pill splitting" approach is a way to buy a more cost-effective dose and then splitting that into the dose you're meant to take.
As a result, Genentech is curbing sales to pharmacies that are able to repackage Avastin for the purpose of off-label usages like treating macular degeneration. This is probably a good idea, because the repackaging/redistribution process is yet another step that can go wrong (contamination, mislabeling etc) that can lead to patient adverse event and liability for the company. Genentech has a very deep pocket and will be the first targeted by lawyers.
From a scientific standpoint, a glance at the prescribing information for Lucentis and Avastin (both from Genentech's website) showed that both drugs do bind to VEGF (vascular endothelial growth factor) and I assume stereically inhibits its binding to the VEGF receptor, but Lucentis appears to be specific for one type of the VEGF receptor (type A).
Thus even if doctors "see" both drugs as equivalent and therefore feel comfortable substituting for patients on a cost-basis, we just don't know what the long term effects are for Avastin in treating wet macular degeneration. Maybe I tend to be overly cautious because I was used to looking at growth factors as "different" even if they are sub types in the same class, but I firmly believe there's an evolutionary rationale for various subtypes even if we haven't figured out the specifics, and substituting can have unintended long term consequences that we may not be ready to deal with.
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