Naxitamab filed with the FDA in a rolling submission for high-risk neuroblastoma.- Y-mAbs Therapeutics

Y-mAbs Therapeutics announced that it has submitted to the FDA the first portions of its Biologics License Application for naxitamab for the treatment of patients with relapsed/refractory high-risk neuroblastoma under the FDA�s Rolling Review process. The Rolling Review process allows Y-mAbs to submit individual portions of the BLA for review, rather than waiting until all portions are completed and submitted to the FDA for review. Upon potential approval, the Company intends to commercialize naxitamab in the U.S.

In October 2019 Y-mAbs Therapeutics announced a clinical update on naxitamab for the treatment of neuroblastoma and osteosarcoma. Data from 28 patients with primary refractory high-risk neuroblastoma in Study 12-230 (NCT01757626) was presented. This comprises patients refractory to intensive induction therapy, and more than half of such patients also refractory to second line chemotherapy. Essentially, this data relates to a subset of patients from Study 12-230 that demonstrate better than expected outcomes, including a 78% overall response rate. The patients received at least five (5) cycles of therapy post major response and a subset subsequently went on to receive the Company�s investigational GD2-GD3 Vaccine at MSK. Overall, in this population a 50% two-year progression free survival was observed. Another subset consisted of 35 patients with relapsed neuroblastoma resistant to salvage therapy, of which 30 patients were evaluable for response in the 12-230 Study. One third of the patients had two (2) or more relapses prior to enrollment and 89% of patients had previously received anti-GD2 therapy. Patients in this subset had a 36% rate of two-year progression-free survival and an overall response rate (ORR) of 37%, which indicated clinical benefit in this difficult to treat population. Data was also presented for patients with high-risk neuroblastoma in second or later complete remission. 44 patients with no evidence of disease (NED) were treated with naxitamab and GM-CSF at MSK as maintenance therapy.

In this population, where 88% had previously received an anti-GD2 therapy and 30% had previously received two or more lines of anti-GD2 therapy, a two-year progression-free survival of 52% was observed. Some of these patients went on to receive the Company�s investigational GD2-GD3 Vaccine at MSK. Due to the absence of macroscopic evaluable disease, these patients were not evaluable for a formal tumor response grading. Therefore, these patients will not form a part of the Company�s efficacy data set for its rolling biologics license application (BLA) filing currently planned to be initiated in November 2019.

Finally, safety data from the Phase II osteosarcoma trial, Study 15-096, for the 25 patients enrolled in the study at MSK was presented. Patients who had recurrent disease and two (2) or more complete remissions were treated with naxitamab and GM-CSF, administered to the patients in an outpatient setting. The Company plans to initiate a multi-center trial in 2020.