Related parties	12 Months Ended
Dec. 31, 2019
Related parties
Related parties	16. Related parties The Company is party to research and service arrangements with the University of Basel. The Company’s Chief Scientific Officer and his spouse are employees of the University of Basel and both involved in providing the services under these arrangements. In the years ended December 31, 2019, 2018 and 2017, the Company recorded $0.3 million, $0.4 million and $0.3 million, respectively, in research and development expenses for service fees paid to the University of Basel. The University of Basel is also entitled to receive de minimis royalties on the net sales of any product that is based on a patent created by the Company’s Chief Scientific Officer in the course of his consulting services to the Company. In the years ended December 31, 2019, 2018 and 2017, no royalties were paid pursuant to the terms of this arrangement. During the year ended December 31, 2019, the Company issued 50,670 shares of Series D Preferred Stock for total gross proceeds of $7.4 million and 1,303,750 shares of common stock for total gross proceeds of $18.3 million to certain stockholders that were related parties as part of the IPO. During the year ended December 31, 2018, the Company issued no shares to stockholders that were related parties. During the year ended December 31, 2017, the Company issued 61,524 shares of Series B Preferred Stock for total proceeds of $4.0 million and 147,712 shares of Series C Preferred Stock for total proceeds of $12.6 million to certain stockholders that were related parties. The due from shareholder amount of $6.5 million as of December 31, 2017 is from one of these related parties.

16. Related parties

The Company is party to research and service arrangements with the University of Basel. The Company’s Chief Scientific Officer and his spouse are employees of the University of Basel and both involved in providing the services under these arrangements. In the years ended December 31, 2019, 2018 and 2017, the Company recorded $0.3 million, $0.4 million and $0.3 million, respectively, in research and development expenses for service fees paid to the University of Basel. The University of Basel is also entitled to receive de minimis royalties on the net sales of any product that is based on a patent created by the Company’s Chief Scientific Officer in the course of his consulting services to the Company. In the years ended December 31, 2019, 2018 and 2017, no royalties were paid pursuant to the terms of this arrangement.

During the year ended December 31, 2019, the Company issued 50,670 shares of Series D Preferred Stock for total gross proceeds of $7.4 million and 1,303,750 shares of common stock for total gross proceeds of $18.3 million to certain stockholders that were related parties as part of the IPO.

During the year ended December 31, 2018, the Company issued no shares to stockholders that were related parties.

During the year ended December 31, 2017, the Company issued 61,524 shares of Series B Preferred Stock for total proceeds of $4.0 million and 147,712 shares of Series C Preferred Stock for total proceeds of $12.6 million to certain stockholders that were related parties. The due from shareholder amount of $6.5 million as of December 31, 2017 is from one of these related parties.