Biotech upstart adds a failed Merck KGaA drug to the pipeline, mapping new combo approach to MAPK pathway
Can a biotech startup succeed where a big pharma player failed? Day One plans to find out after in-licensing a pair of discards from Merck KGaA.
The biotech has struck a deal — without disclosing any terms — for two MEK 1/2 inhibitors, pimasertib and MSC2015103B from the German company.
Pimasertib was shelved by Merck KGaA after producing mixed results through a big campaign involving 10 Phase I/II studies. One of those involved a combination approach with gemcitabine that flopped in pancreatic cancer.
The biotech, though, believes it has better odds of success when paired with their type II pan-RAF kinase inhibitor Day101, a therapy they hauled in from Takeda. The plan is to go back into solid tumors with MAPK pathway aberrations.

The South San Francisco-based Day One has raised more than $190 million since launching, including a $130 million round announced a few weeks ago, and now has a Phase II glioma study underway.
“There is strong scientific and clinical rationale for targeting multiple nodes of the MAPK signaling pathway to drive deeper and more durable tumor responses,” said Samuel Blackman, co-founder and chief medical officer of Day One. “DAY101 demonstrated encouraging single agent anti-tumor activity in pediatric low-grade glioma, and we believe the combination of pimasertib and DAY101 will be well-suited for adult patients with solid tumors given their greater heterogeneity. Further, data have shown DAY101 to selectively inhibit both RAF monomers and dimers which may broaden its potential clinical application in combination with MEK inhibition in solid tumors driven by non-BRAF V600 mutations and RAF fusions. We look forward to initiating a Phase 1/2 combination study later this year.”
CEO Jeremy Bender (Day One)