September 15, 2016
By Mark Terry, BioSpace.com Breaking News Staff
As yesterday’s BioSpace article on why Gilead might consider acquiring Tesaro underlined, there’s a new class of cancer drug, PARP inhibitors (PARPi) that has caught pharma’s attention. As Max Nisen writes in Bloomberg Gadfly today, “The list of available near-market cancer drugs with blockbuster potential is short.” Let’s take a look.
PARP stands for poly ADP ribose polymerase, which is an enzyme that many cancer cells are more dependent upon than regular, healthy cells are. Drugs that inhibit PARP have the potential to be a new and effective form of cancer treatment.
To date, only AstraZeneca has a PARPi on the market, Lynparza, for BRCA-positive advanced ovarian cancer. Others include Tesaro’s niraparib, AbbVie ’s veliparib, Clovis Oncology ’s rucaparib, and Medivation ’s (now Pfizer ’s) talazoparib.
Although Pfizer’s primary interest in Medivation was undoubtedly its blockbuster prostate cancer drug Xtandi, talazopraib for breast cancer patients with BRCA mutations was also likely a factor. The drug is also being evaluated in small cell lung cancer, prostate cancer and ovarian cancer.
In terms of Tesaro, which is headquartered in Waltham, Massachusetts, the company announced on June 29 that its Phase III trial of niraparib met its endpoints of progress-free survival (PFS) in patients with ovarian cancer. It expects to file for approval with the U.S. Food and Drug Administration (FDA) by the end of this year, with a final decision expected in 2017.
Nisen writes, “Wall Street’s consensus forecast for the drug’s 2020 sales jumped by more than $400 million immediately after Tesaro released the results. Tesaro announced Monday it had received a fast-track designation from the FDA, meaning a potentially quicker path to an approval already hoped for in 2017.”
Clovis , with headquarters in Boulder, Colorado, announced on August 23 that the FDA had accepted its New Drug Application (NDA) for rucaparib and given it accelerated approval. Its PDUFA date is February 23, 2017. The drug is being evaluated as a treatment for advanced ovarian cancer in patients with deleterious BRCA-mutated tumors inclusive of both germline and somatic BRCA mutations.
And as yesterday’s article about Gilead as a potential buyer of Tesaro indicates, small companies with potential blockbuster cancer drugs make for tempting acquisition targets. And if Pfizer acquired Medivation in part because of its PARPi, there were several other companies interested as well who may still want to buy a PARPi, including Celgene , Merck , Amgen , Sanofi , and AstraZeneca.
So far, the various PARPi drugs are being tested in different types of cancers or in different populations. That makes it hard to compare the various drugs or for anyone to determine which ones are “best in class,” if any of them are. Nisen writes, “That may not stop the drugmakers and their potential acquirers from hoping their drug is the one PARP inhibitor to rule them all—a blockbuster that will ride multiple approvals to multi-billion-dollar sales. Others might believe their drugs are close enough to best that they could still net a significant return.”
Johnson & Johnson currently has the rights to develop Tesaro’s niraparib for prostate cancer. Will it want to get hold of a drug that might be approved for a number of other cancer indications? Or will one of the other big players in the oncology market?
As Nisen says, “Pursuing firms could pay up for Tesaro and its high hopes … or they could seek a discount with Clovis. That company’s trial results don’t look quite as good. But at a roughly $1 billion enterprise value after the implosion of a separate lung-cancer drug last year, it’s far more snackable.”
