Rain Therapeutics nets $18M to push lung cancer asset into phase 2

The series A brings Rain's total haul to $19.4 million and allows it to complete an open-label phase 2 trial for Tarlox in NSCLC. (kai kalhh)

Rain Therapeutics raised $18.4 million in series A funding, which will advance its lead program, a hypoxia-activated prodrug, in a population of patients with non-small cell lung cancer for whom there are no treatments. 

The Bay Area biotech is going after areas of unmet need in cancer treatment and is developing tarloxitinib, dubbed Tarlox, for NSCLC patients with EGFR and Exon 20 insertion mutations. Co-founder Robert Doebele, M.D., Ph.D., identified this population—their cancer is driven by EGFR (epidermal growth factor receptor), but they do not respond to standard EGFR inhibitors. Rain licensed the treatment from the University of Auckland. 

"The reason for that is their specific mutation appears to look very similar to wild-type EGFR, which occurs in abundance in places like the digestive tract and skin," said CEO and co-founder Avanish Vellanki. The challenge in developing an inhibitor for these patients is distinguishing between EGFR in the tumor and EGFR in healthy tissue. 

"We believe that any drug that effectively inhibits EGFR signaling in the tumor will bring with it tremendous side effects," Vellanki said. With Tarlox, the company thinks it has a more tolerable, effective drug that will improve patients' quality of life and extend the time a patient can stay on the treatment. 

The series A brings Rain's total haul to $19.4 million and allows it to complete an open-label phase 2 trial for Tarlox in NSCLC, Vellanki said. 

And this may not be the end of the road for Tarlox: "It stands to reason that we should see activity in all EGFR-driven cancers, of which there are many. This [study] is in large part a proof of principle not just for the Exon 20 population, but for the wild-type EGFR-driven cancer population," he said. "We think any tumor population dependent on EGFR signaling could be an opportunity for us." 

Beyond this, the company plans to license and develop in-house new molecules for other cancer patient subpopulations whose needs are not being met. Rain is just three employees strong today, but plans to grow to about 12 to 15 staffers in the next year or two. 

Other companies have faced hurdles while working on EGFR drugs, including Astellas, which scrapped its NSCLC program after an independent data monitoring committee recommended it pull the plug on its EGFR tyrosine kinase inhibitor ASP8273.