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Chimerix antiviral didn’t improve survival rates in clinical trial

In another potential disappointment for Chimerix, the Durham drug maker said Monday its experimental antiviral had not improved the survival rate of infected patients in an ongoing clinical trial.

Chimerix said the antiviral, called brincidofovir, rapidly reduced the levels of adenovirus in infected patients, even to the point that that the deadly virus could not be detected in the body.

But in an ongoing AdVise clinical trial, patients treated with brincidofovir did not exhibit a meaningful difference in survival rates, Chimerix said. Patient survival rates could not be assessed reliably because other factors that could have influenced who lived and died.

“We are facing the challenges that always confront those that attempt to bring forward the first drug to treat a condition,” Chimerix chief medical officer Garrett Nichols told analysts during a conference call Monday.

On Monday, the company reported a net loss of $26.3 million in the first quarter of 2016, compared with a net loss of $22.3 million during the same period a year ago. First-quarter revenue was flat at $1.2 million.

Chimerix’s revenue comes from a federal research contract it has with the Biomedical Advanced Research and Development Authority, or BARDA. The company ended the quarter with $315.7 million in cash, which could sustain operations into 2019, said the William Blair research firm.

Chimerix said it plans to meet with Food and Drug Administration officials to set up another clinical trial that is better designed to measure patient survival rates. That strategy could add many months to the development of brincidofovir as a treatment for adenovirus infection, even though Chimerix executives noted that the medication has patent exclusivity through 2034.

“Today’s update would appear to eliminate the potential rapid path forward for [brincidofovir] based on AdVise and leaves the path forward uncertain,” J.P. Morgan analysts wrote in a research note Monday.

Chimerix shares fell 21 cents, or 4 percent, to close at $4.91. The stock is down 45 percent this year and has fallen more than 90 percent from a high of $58.04 last August.

Adenovirus causes the common cold in healthy people but is potentially fatal for patients with compromised immune systems after undergoing bone marrow transplants. There is currently no approved therapy for adenovirus infection, and the mortality rate of infected children is greater than 50 percent in the first three months after diagnosis, Chimerix said.

In the ongoing AdVise trial, pediatric patients had a 32 percent mortality at day 90 and 42 percent mortality at week 24.

Adult mortality was 57 percent at day 90 and 71 percent at week 24, Chimerix reported.

“Adenovirus is an opportunistic infection in these patients,” Nichols said. “And so they are not just at risk for dying from adenovirus, but they are also at risk for dying from a variety of other complications of their transplant, including other incident infections.”

According to Chimerix, the AdVise clinical trial had controls for such factors as age, transplant type, and presence or absence of disseminated adenovirus infection. However, the outcomes could have been affected by other factors, such as confirmed end-organ adenovirus disease, low lymphocyte count, as well as graft-versus-host disease, a complication from stem cell or bone marrow transplant in which the newly transplanteded cells attack the patient’s body.

Earlier this year, Chimerix said that brincidofovir failed to prevent infection for cytomegalovirus in patients who had undergone bone marrow transplants. Like the adenovirus, the cytomegalovirus is innocuous in healthy people. Typically, healthy people don’t know they’ve been infected with cytomegalovirus, which remains in the body for life in a dormant state.

That setback on the cytomegalovirus study prompted the FDA to require Chimerix to provide Monday’s update on the AdVise clinical trial. Even though Chimerix will have to run another clinical trial, company executives interpreted the mixed results as positive.

“We provided the interim data on the all-cause mortality and today are sharing what we believe is a significantly lower 90-day and 24-week mortality than what would have occurred in the absence of brinci,” Nichols said. “And as we’ve seen with other antivirals, the rapid reduction of adenovirus ... is below the limit of detection, correlates with improved survival.”

The 100-employee company is developing brincidofovir as a potent antiviral with fewer dangerous side effects to existing treatments. Brincidofovir is being developed to treat kidney transplant patients, smallpox infections and other potential viral attacks.

John Murawski: 919-829-8932, @johnmurawski

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