Piper Jaffray analyst William Quirk points out that Myriad Genetics (MYGN) partner TESARO (TSRO) used the company's myChoice HRD test to determine patients who were HRD positive and more likely to respond to niraparib. TESARO earlier this week presented positive data on niraparib. Patients, however, who were HRD negative still showed an absolute benefit over placebo, Quirk tells investors in a research note. He does not believe this is statistically significant. Nonetheless, if niraparib does not work in HRD negative patients, Myriad's test opportunity is $200M beginning in the second half of 2017, he estimates. If niraparib works in HRD negative patients, Quirk believes myChoice HRD's market opportunity could be substantially lower for this indication. TESARO will present the full data set including how niraparib performed in HRD negative patients in early October. Quirk has an Overweight rating on Myriad Genetics with a $47 price target.