TESARO Inc (NASDAQ:TSRO): Here’s Our Take On The Data


TESARO Inc (NASDAQ:TSRO) put out data from its lead ovarian cancer treatment over the weekend, and the company has enjoyed an incredibly strong start to the week as a result. The data came out as very supportive of an efficacy thesis, and it looks pretty much a shoo-in for approval come submission review.

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There are a couple of things not totally addressed in the mainstream coverage of the data, however, so here’s our take on what the numbers mean, and beyond that, what they mean for Tesaro going forward.

First, a quick introduction to the drug in question.

It’s called niraparib, and we’ve covered it on a number of occasions in the past. In fact, we first highlighted Tesaro as being a company to keep an eye on back during the middle of September, in anticipation of the weekend just gone’s release.

It’s part of a family of drugs called PAR inhibitors – a family in which most of the big names in oncology have dabbled over the last half decade. They are designed to stop the DNA reparation action of an enzyme called poly ADP ribose polymerase, the PARP in the drug’s descriptive title. When cells replicate, the DNA that controls the process becomes damaged in the newly formed cell. Normally, and in healthy cells, an enzyme called PARP will go around fixing the small damaged sections ahead of further replication.

Because cancer cells replicate so much, they require a large amount of the PARP enzyme to facilitate the fixing if their DNA to an appropriate scale. Without lots of PARP, the DNA doesn’t get repaired, and the newly formed cancerous cells that form on the back of damaged DNA don’t live long enough to replicate themselves. Niraparib is a PARP inhibitor, meaning it attempts to stop the PARP from fixing the DNA in the cancerous cells, inducing early apoptosis and – in turn – stopping tumor cells from spreading.

Pretty neat MOA, right?

Well, it’s not that simple. A number of companies have failed in their PARP inhibitor programs, including Pfizer Inc. (NYSE:PFE), and this cast some doubt as to whether Tesaro could come up with the goods come data date.

Bottom line, however, is it did.

The data first hit in June, but it wasn’t until this weekend that we got a detailed look at the numbers in question. We won’t go into too much detail on the numbers here – they are available pretty much everywhere else – but as a brief overview, the company hit it out of the park in BRCA-mutated recurrent ovarian cancer (median PFS 21 months) and performed well in non-BRCA-mutated recurrent ovarian cancer (9-13 months across various incarnations). The numbers are between 3-4 times what a patient could expect without the drug, hence our shoo-in statement above.

Something to consider…

There may be a limiting factor in the company’s non BRCA and HRD negative results. In this arm of the trial, median tumor progression only delayed by a little over 3 months. The FDA has turned a drug down in this indication in the past for similar impact (the above mentioned Pfizer candidate) and this paints a potential scenario whereby the company has to target only a subset of ovarian cancer sufferers, and not the entire market.

Having said this, even with a limiting factor in place the company is going to have nearly 15,000 potential patients to go after, and in late stage oncology, this is more than enough to generate a billion dollars in revenue on an annual basis.

All said, this is a great outcome for Tesaro, and one that is probably going to result in a steady increase in market capitalization ahead of NDA submission for the drug. As the FDA takes it under consideration, expect Tesaro strength.


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