Note 8 - Net Loss Per Share Attributable to Common Stockholders (Tables)

6 Months Ended

Jun. 30, 2018

Notes Tables

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]

	Three Months Ended June 30,				Six Months Ended June 30,
	2018		2017		2018		2017
Outstanding stock options		4,447,226		2,783,570		4,447,226		2,783,570
Convertible preferred stock		22,112,775		-		22,112,775		-
		26,560,001		2,783,570		26,560,001		2,783,570