Y-mAbs Upsizes IPO, Gets $96M to Test Two Pediatric Cancer Drugs

Xconomy New York — 

Cancer drug developer Y-mAbs Therapeutics is the latest biotech company to go public, raising $96 million in its IPO.

New York-based Y-mAbs priced its offering of 6 million shares at $16 each, which was the high end of its projected range. The company had planned to sell 5.3 million shares priced at $14 to $16 apiece. Y-mAbs shares are expected to begin trading on the Nasdaq exchange later today under the stock symbol “YMAB.”

Y-mAbs aims to treat neuroblastoma, a rare pediatric cancer that has no FDA-approved drugs for patients whose disease has progressed after initial treatment. Neuroblastoma affects nerve cells that are still in development. According to the American Cancer Society, it’s the most common cancer in infants and accounts for about 6 percent of all cancers in children.

Two Y-mAbs antibody drugs are in clinical development for neuroblastoma. The first, naxitamab, targets a molecule on the surface of tumors called GD2. The company says its drug could be less toxic, and require less frequent dosing compared to other GD2 drugs. United Therapeutics (NASDAQ: UTHR) drug dinutuximab (Unituxin) also targets GD2 and was approved in 2015 for patients who have at least a partial response to the first line of cancer treatments. But that drug comes with an FDA warning about potentially life-threatening side effects. Y-mAbs believes positive data from an ongoing naxitamab Phase 2 study and an earlier trial may be enough to file for FDA approval in neuroblastoma, according to the prospectus.

The second Y-mAbs drug, omburtamab, was developed to treat neuroblastoma complication leptomeningeal metastases, which occurs when the disease spreads to the membranes surrounding the brain and spinal cord. Omburtamab has only been tested in a Phase 1 study, but Y-mAbs is aiming for a quick path to approval for that drug as well. The company says an analysis of 93 patients shows median overall survival of those treated with the drug was 47 months, compared to the historical median overall survival of six months. Y-mAbs is planning to treat an additional 18 patients in a Phase 2 study using omburtamab produced by a commercial manufacturer rather than drug produced by Memorial Sloan Kettering Cancer Center, where the study was conducted. The company has proposed to the FDA that data from both studies be pooled together and used to apply for regulatory approval.

Y-mAbs says it aims to submit both neuroblastoma drugs for FDA review in 2019. The company plans to use $34.5 million of the IPO cash for finish clinical testing of naxitamabanother $24.4 million for omburtamab, and the rest on earlier-stage drug programs, also in cancer.

Founded in 2015, Y-mAbs licensed its drugs from Sloan Kettering. The New York cancer center will earn milestone payments if the drugs progress, and royalties from sales if they reach the market. But Sloan Kettering could get another big payoff from a priority review voucher, which the FDA awards to companies as an incentive to develop drugs that treat rare diseases. The FDA can award a voucher to Y-mAbs if it receives approval for one or both of its drugs, which the company can then use for speedier regulatory review of another drug that treats a rare disease. But these vouchers have become valuable commodities, sold for as much $130 million or more. According to the Y-mAbs prospectus, Sloan Kettering would get half of the proceeds from the sale of the first priority review voucher.

Neuroblastoma image by the National Cancer Institute