Note 11 - Related Party Transactions (Details Textual)
$ in Thousands
|6 Months Ended|
Jun. 30, 2019
|Moores Cancer Center at University of California San Diego [Member] | Research and Development Expense, Related Party [Member]|
|Related Party Transaction, Amounts of Transaction||$ 135|
Amount of transactions with related party during the financial reporting period.
Reference 1: http://www.xbrl.org/2003/role/disclosureRef