* Patients negative to Myriad HRD diagnostic test also
* Their median progression-free survival benefit 3.1 months
* Lead researcher sees no need for Myriad test
* Growing interest in PARP inhibitor cancer drug class
(Adds further comments from study leader and Myriad)
By Ben Hirschler
COPENHAGEN, Oct 8 Tesaro's experimental
drug niraparib improved outcomes for all women with recurrent
ovarian cancer in a clinical study, boosting prospects for the
product, part of a closely watched class of new medicines called
The finding suggests that a Myriad Genetics
companion diagnostic test, designed to select suitable patients,
may not be necessary.
U.S. biotech company Tesaro already cheered investors in
June by saying that the study had met the main goal of
prolonging survival without disease worsening, but full results
were only reported at the annual European Society for Medical
Oncology congress in Copenhagen.
The treatment helped patients live longer without their
disease progressing. Even those least likely to be helped by the
drug because of their genetic profile saw a benefit of 3.1
months, researchers told the meeting on Saturday.
Niraparib and other PARP inhibitors block enzymes involved
in repairing damaged DNA, thereby helping to kill cancer cells.
AstraZeneca's Lynparza became first of the new class
of drug to reach the market when it won U.S. approval at the end
of 2014, but it was only cleared for patients whose cancer
tested positive for defective BRCA genes.
Tesaro hopes to show its drug can work across the entire
population of women needing maintenance therapy for ovarian
cancer after being given platinum-based chemotherapy.
Study leader Mansoor Raza Mirza of Copenhagen University
believes that case has now been made.
"Our conclusion is that all patients have a benefit and all
patients must be treated," he told reporters at the meeting.
"This is a breakthrough for patients with ovarian cancer. We
have never seen such large benefits in progression-free survival
(PFS) in recurrent ovarian cancer."
The latest findings showed that various patient populations
all responded, with the biggest median PFS of 15.5 months seen
in the BRCA mutation group.
However, even those with no BRCA mutation and who tested
negative to another test called HRD, made by Myriad, still saw a
benefit of 3.1 months.
There is now likely to be debate among doctors and investors
as to whether this is enough for Tesaro to win very broad
approval for its drug or whether it should be reserved for a
narrower group of patients based on genetic testing.
Mirza is convinced it should be used widely and dismissed
the need for the HRD test. "You don't need it because all
patients benefit," he said.
He estimates niraparib could benefit 70 percent of all
ovarian cancer patients, against 15 to 20 percent who are
currently deemed suited for AstraZeneca's Lynparza.
Myriad's chief medical officer, Johnathan Lancaster,
contested Mirza's view, arguing that a treatment benefit of just
over three months was modest and patient selection still made
Results of the study were also published online in the New
England Journal of Medicine.
Interest in PARP inhibitors has grown apace over the last
year as drug developers try to target DNA repair mechanisms
inside cells as a way to fight cancer.
Other companies with PARP inhibitors in development include
Clovis, AbbVie and Medivation, which was
recently bought by Pfizer for $14 billion.
(Editing by Alexander Smith and John Stonestreet)