nl-201 nl-201 nl-201 was an immunotherapy drug candidate that underwent a phase 1 human clinical trial in cancer patients. it is a de novo protein that was first computationally designed at the institute of protein design (ipd), university of washington. in november 2022, neoleukin therapeutics announced it would discontinue the development of nl-201. history the predecessor of nl-201, neoleukin-2/15, was first described and published on nature magazine in january 2019. the citizen science distributed computing project rosetta@home, based at the university of washington, contributed with "forward folding" experiments that helped validate protein designs of neoleukin-2/15, from which nl-201 was further developed by neoleukin therapeutics, a biopharmaceutical company that originated at the ipd. the phase 1 human clinical trial began on may 5, 2021. in january 2022, neoleukin therapeutics announced a collaboration with merck for a combination clinical trial of merck's pembrolizumab and neoleukin's nl-201. in november 2022, neoleukin therapeutics announced it would discontinue the development of nl-201.