EMERGING TESTS

Study Showing PGx Testing Improves Depression Outcomes, Key to Myriad’s Reimbursement Strategy

Pharmacogenomic testing (PGx) provides clinically meaningful improvement in response and remission rates for difficult-to-treat depression patients over standard of care, according to a study published Jan. 4 in Journal of Psychiatric Research. Although the study did not find significant improvement in symptoms, leadership at Myriad Genetics (Salt Lake City) are optimistic about the findings from the large randomized controlled trial and about reimbursement prospects.

Current antidepressant prescribing practices for major depressive disorder (MDD) are described as trial and error and previous studies have shown that more than half of patients with moderate-to-severe MDD do not respond adequately to their first medication, which foretells worsened long-term prognosis. Many in the field of psychiatry have been hopeful that PGx can better inform prescribing practices.

The first generation of PGx tests focused on single gene analysis. Even PGx panels interrogate single gene-drug interactions for each evaluated gene. Assurex Health, (Mason, Ohio; acquired by Myriad in 2016) developed the multigene PGx test GeneSight that evaluates 59 alleles and variants across eight genes using an algorithm. Genotypes for all measured variants are weighted and combined in order to categorize 38 psychotropic medications based on three levels of gene-drug interaction: “use as directed'” (no detected gene-drug interactions), “use with caution” (moderate interactions; medications may be effective with changes in dose), or “use with increased caution and with more frequent monitoring” (severe gene-drug interactions may significantly impact drug safety and/or efficacy).

In the Genomics Used to Improve DEpression Decisions (GUIDED) trial, 1,167 outpatients diagnosed with MDD and with an inadequate response to at least one antidepressant were randomized to treatment as usual (TAU) or a PGx-guided intervention arm (guided-care). Participants (70.6 percent female; mean age 47.5 years) were enrolled from 60 academic and community sites, assessed at weeks 0 (baseline), 4, 8, 12, and 24. Only 913 of the 1,167 completed the full 24 weeks.

PGx Saves Payers Money

The use of PGx to guide medication treatment for psychiatric disorders can yield “material savings” for large commercial payers, according to a study published in September 2018 in Personalized Medicine.

The researchers used claims from a large payer database compiled by OptumInsight to evaluate payer costs associated with treating patients with psychiatric disorders (depression, anxiety, bipolar disorder, panic disorder, post traumatic stress disorder, obsessive compulsive disorder, and schizophrenia). Cost data were compared for patient care (inpatient, hospital-based outpatient, physician, and pharmacy) for 2,015 using the GeneSight test versus 478 patients with treatment-as-usual (TAU) over the 12-month period following PGx.

The analysis showed that, overall, the average total costs savings were $5,505 in the PGx group versus TAU ($17,627 versus $23,132).  In subgroup analysis of patients with depression the costs savings were even larger, reaching $6,050 in the first year after testing ($18,741 versus $24,791).

“Since the test cost is a one-time investment, average savings are expected to increase as the duration is extended over the life cycle of psychiatric treatment,” write the authors led by Joachim Benitez, from Weill Cornell Medical College in New York.

The researchers report that at enrollment, patients had failed a mean of 3.5 medications. Overall, at week 8, symptom improvement for guided-care was not significantly different than TAU (27.2 percent versus 24.4 percent). However, improvements in response and remission were statistically significant.

Prior to PGx-guided treatment change, at baseline, 79.4 percent of patients in the guided-care arm and 77.5 percent of patients in TAU were prescribed medications that were congruent with the PGx test report. The proportion of patients prescribed congruent medications at week 8 increased to 91.2 percent in the guided-care group and remained relatively unchanged in TAU. Importantly, though, looking only at the subset of patients taking incongruent medications at baseline who switched to congruent medications by week 8, there were significant improvements in all three measures—symptoms, response, and remission—compared to those remaining on incongruent medications.

“The overall impact of PGx testing in this trial may have been diluted by the large proportion of patients already taking genetically congruent medications,” write the authors led by John Greden, from University of Michigan in Ann Arbor. Further, when “the subset of patients taking incongruent medications at baseline were evaluated, side effect burden was significantly reduced when patients switched to congruent medications.”

Several authors report financial ties to Assurex and/or the pharmaceutical industry.

The Future of PGx Testing
In April 2018, the American Psychiatric Association said the evidence was “insufficient” to support widespread clinical use of PGx panels for personalizing antidepressant treatment. While failure to include such testing in clinical guidelines is a headwind, both Myriad leadership and Wall Street analysts are optimistic that publication of the GUIDED trial’s results will meaningfully impact reimbursement prospects for the company.

Myriad CEO Mark Capone said on the company’s Nov. 6, 2018 earnings call, “We are positioned to materially advance reimbursement for GeneSight.” More recently, at the January J.P. Morgan Healthcare Conference (Jan. 7-10; San Francisco) Capone said that the test is the firm’s “most important” for future growth.

On the earnings call, Capone said that for quarter 1 2019 GeneSight had 28 percent year-over-year volume growth, with 15,500 total ordering physicians and 2,500 new ordering physicians. “Fully reimbursed at our targeted average selling price, this GeneSight volume would represent greater than $600 million in revenue,” Capone said.

The company is pursing additional GeneSight commercial coverage and expanded Medicare local coverage determinations to drive a “significant inflection in revenue.” Following positive reimbursement decisions, the company plans to launch into the primary care market along with a campaign to raise awareness directly among patients with depression.

Takeaway: Myriad is optimistic that recent published results show that PGx can improve patient outcomes, while saving payers money. The company believes this evidence will be paramount in achieving improved reimbursement.

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