IDRx launches with $122M to develop combo therapy that addresses precision medicine 'whack-a-mole'

Describing a new treatment as “precision medicine” has become so commonplace it feels like the term has blended in with the plethora of pharma jargon that means everything and nothing at the same time. But the founders of IDRx are hoping to jolt meaning back into the modality with specified cancer treatments.

Evidently, investors are on board, pouring in $122 million in series A funding to launch the company already equipped with two assets aimed at mutations of non-PDGFR-driven gastrointestinal stromal tumors (GISTs). The first, IDRX-42, was licensed from Merck KGaA and has since nabbed orphan-drug designation from the FDA. According to the company’s executives, the therapy is slated to begin dosing in a phase 1 trial later in August.

The second program, IDRX-73, is expected to enter the clinic in the second half of next year. But it’s the combination of both of these tyrosine kinase inhibitors that has leaders of the company excited, particularly when it comes to targeting GIST. 

“We know a lot about the biology [of GIST] at this point,” said co-founder Alexis Borisy, a serial biotech entrepreneur who also co-founded EQRxRelay Therapeutics and Blueprint Medicines. “So we can anticipate all the different mutations, like the whack-a-mole that you have to hit.” 

Anticipating those mutations is where the combo therapy comes in. The first drug hits right at the main disease driver, and the second blocks the resistance pathways that cancer tries to utilize after the first round of treatment. The model for Borisy and IDRx CEO Ben Auspitz is Novartis’ blockbuster leukemia treatment Gleevec, also a kinase inhibitor. 

And, like Gleevec, the company hopes the clinical data are strong enough to warrant accelerated approval. The expectation is that the regimen would serve as a second-line treatment, right up the alley of the FDA’s Project FrontRunner, an initiative pushed by the agency’s cancer czar, Richard Pazdur, M.D., to hand accelerated approval to earlier line treatments. 

Borisy says this plan could also serve as a win-win if they take the accelerated pathway given that the company would likely need to run a randomized, control study to prove a clinical benefit as an earlier line treatment. If that’s the case, then the company would, in theory, be able to monitor the same patient population for overall survival data that could inform a potential confirmatory trial. But Borisy emphasized this is contingent on the regimen being tolerable, a focus point for IDRx.

“[T]o enroll those patients, to have the right value proposition for physicians and patients, you need to be safe enough to be used in those early lines of treatment,” he said. “This is part of the difference in the thinking in IDRx—don't just take combinations of what already exists, but engineer it from the get-go with the design requirements to really make that transformative difference.”

The fundraising haul—led by VC firms Andreessen Horowitz (a16z) and Casdin Capital—is intended to support the company’s development of the combo therapy, which Auspitz loosely estimated was about three years. He added that he and Borisy believe there may be a broader application for the two drugs, but that’s not the current focus. 

“But it is our vision and our goal to be a broader company [and] align this idea to other areas of cancer,” he said.