Zytiga – practice-changing clinical news but is it a home run?

ASCO provided practice-changing news for prostate cancer patients – Zytiga (abiraterone) added to standard hormone therapy in newly diagnosed high risk metastatic patients reduces the chance of death by almost 40%, and median time to disease progression increased from ca. 15 months to 33 months. This brings the drug into the very large population of patients who are at earlier stages of the disease than the currently approved label, offering tremendous hope to those men as well as the prospects of fabulous financial returns for J&J and the entities that may still be receiving royalty payments on the drug.

As put by Benjamin Davies in Forbes[1], this presents payers with a “Sovaldi-sized problem”. In the USA, however, there’s practically nothing that payers can do about this as reimbursement for cancer is all but obligatory especially in the face of this truly compelling new data. But it’s not a home run.

The fly in the ointment is the Zytiga patent: the composition of matter patent expired last year. However, three years after the initial NDA, J&J received approval for an additional patent, which will extend the period of exclusivity potentially into 2027. This new patent covers the “method-of-use”, specifically the coadministration of prednisone with Zytiga, a dosing regimen that was already prescribed in the FDA-approved product label. The additional patent for Zytiga (US 8,822,438) is listed in the FDA’s Orange Book. Companies filing applications to market generic Zytiga will be required to certify to FDA that they do not infringe the dosing regimen patent. From a lay perspective (I’m not a patent attorney), it’s not clear how strong this supplementary patent will prove in the courts. Prednisone can be considered cortisol “replacement”, which can help reduce side effects from Zytiga as it lowers blood levels of cortisol in many patients. Addition of prednisone is common in many cancer therapeutic regimens, so one might question the patentability of Zytiga/prednisone on obviousness grounds. Additionally, www.clinicaltrials.gov received details of the STAMPEDE clinical trial of Zytiga which disclosed the use of prednisone on 20 December 2005 and this may have entered the public domain before the earliest priority date of the supplementary patent, thereby potentially destroying novelty. Doubtless, issues like this will be keeping lawyers and courts busy for many months.

In the current political climate, and in the face of a growing uproar over alleged price gouging in pharmaceuticals, it will be very interesting to see where the chips fall.

 

[1] https://www.forbes.com/sites/benjamindavies/2017/06/05/prostate-cancer-drug-about-to-confront-insurers-with-sovaldi-size-problem/#67845f0956a7

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