Good day for Day One as pediatric brain tumor drug proves worth in phase 2

Seven months after Day One posted positive initial data for its brain tumor drug, the therapy still appears to be on track for success—proving its effectiveness in a phase 2 trial.

The therapy, dubbed tovorafenib, boasted an overall response rate of 64% among the 69 evaluable patients with pediatric low-grade glioma, keeping the biotech on track to submit an approval application to the FDA in the first half of the year.

The FIREFLY-1 trial also saw tovorafenib demonstrate a 91% clinical benefit rate, with 4% of participants seeing a complete response, 59% a partial response and 28% stable disease.

The lack of available treatments for this patient population mean analysts have been keeping a close eye on tovorafenib’s journey through the clinic. Despite being the most common brain tumor diagnosed in children there are no approved therapies for the majority of patients. What’s more, 86% of patients in the trial had a BRAF fusion alteration, for which there remain no approved systemic therapies.

The trial was made up of folks between the ages of six months and 25 years, having tried an average of three previous therapies for their condition. As well as the FIREFLY-1 trial, the biotech has a phase 3 in progress to evaluate giving tovorafenib as a first-line treatment to patients with newly-diagnosed glioma.

Safety data continued to show tovorafenib to be generally well-tolerated, Day One said, with the most common side effects being a change in hair color (75%), increased creatine phosphokinase (64%), anemia (46%), fatigue (42%) and maculopapular rash (42%).

“Based on the efficacy and safety profile of tovorafenib observed to date from the FIREFLY-1 trial population, we plan to submit a New Drug Application in the first half of this year that will include additional follow-up from the full study population,” said CEO Jeremy Bender, Ph.D. “We look forward to continuing our discussions with regulatory authorities with the hope of bringing this therapy to children in need of new options as soon as possible.”

When initial data in June suggested tovorafenib worked, investors sent Day One’s shares doubling in value to over the $15 mark. With the company’s stock continuing to buck the industry trend by rising over the following months, Sunday’s news gave the shares a more modest 12% bump to $23.80 in the opening hours of trading on Monday.

The biotech licensed tovorafenib—a highly-selective type 2 pan-RAF kinase inhibitor—from Sunesis Pharma. It has already been granted breakthrough therapy and rare pediatric disease designations by the FDA for patients with pLGG harboring an activating BRAF alteration, as well as orphan drug designation from the FDA for treating malignant glioma.

Founded to tackle the lack of treatment options in pediatric cancer, Day One’s name reflects its mission to redefine “the day one talk” clinicians have with patients and families about initial diagnosis and treatment plan. Despite scores of new cancer medicines approved in recent years—such as checkpoint inhibitors, new targeted treatments and CAR-T therapies—children often remain an afterthought in cancer drug development.