Shares of Ignyta $RXDX erupted this morning after the biotech reported that its carefully calibrated approach to non-small cell lung cancer had paid off with some promising preliminary data.
Ignyta and Loxo $LOXO have both distinguished themselves by taking a tumor-agnostic approach to cancer drug development, focusing on a specific genetic mutation that drives cancer. In the latest update, investigators for the company say that their drug entrectinib — which targets ROS1 fusion genes that drive a thin slice of all NSCLC cases — achieved a 69% overall response rate for lung cancer confirmed by independent observers. And the median progression-free survival rate was 29.6 months.
This is a single-arm study, with no comparator drug. But those data were good for an initial 28% spike in the biotech’s share price. However, by the market’s close, the gains shrank down to 13% as some analysts wondered if the gains registered on a tiny number of patients could withstand the pressure of a larger trial with more subjects.
Significantly, 5 of the 6 patients who had measurable brain metastases demonstrated a response to the drug — something the current ROS1-positive standard of care Xalkori can’t do. And brain metastases are a major threat in lung cancer cases, offering a new avenue to blunt disease progression and improve durability in responses.
When Pfizer won an approval to use Xalkori in 2016 for ROS1-positive cases, researchers posted a 66% response rate with a treatment effect that lasted 18.3 months. That’s the mark that Ignyta has to beat.
Pfizer, though, has a successor to Xalkori — lorlatinib — that does go after brain metastases in ROS1-positive advanced non-small cell lung cancer. New data hit earlier this week, and Pfizer is already marching to regulators with a new drug and perhaps a new set of goal posts for Ignyta and other rivals in the field.
The goal at Ignyta is to develop drugs that can do a much better job at combatting cancers that involve much smaller subgroups than most of the cancer drugs now in the market, offering a more precise approach that promises to be far more durable.
The FDA flagged the drug with its breakthrough drug designation in antitumor activity across NTRK-positive solid tumors. The EU came through this week with its own PRIME designation, which also looks to speed along promising drugs. Right now the biotech is assembling the early data it needs to go after an accelerated approval, heading to an FDA that has become highly attuned to the potential for this field of research.
A company spokesperson tells me that the applications for both the NTRK tissue-agnostic and the ROS1-positive NSCLC work should go out next year.
“ROS1 fusions (when two chromosomes fuse into a cancer driving oncogene) occur in approximately two percent of all cases of NSCLC and, given the propensity for these tumors to metastasize to the brain, the CNS activity of entrectinib is a critical differentiating feature of the compound and may be contributing to the impressive duration and progression free survival it has demonstrated thus far,” said Myung-Ju Ahn, professor in the department of hematology and oncology at the Samsung Medical Center in Seoul, Korea and study author.
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