Note 7 - Common Stock and Common Stock Warrants - Common Stock Warrants Outstanding (Details)	Mar. 31, 2023 $ / shares shares
Common Stock Warrants Related to Registered Direct Offering 1 [Member]
Exercise price (in dollars per share) | $ / shares	$ 1.88
Number of warrants (in shares) | shares	3,990,025
Pre-funded Warrants Related to Private Placement [Member]
Exercise price (in dollars per share) | $ / shares	$ 0.0001
Number of warrants (in shares) | shares	15,870,199
Common Stock Warrants Related to Registered Direct Offering 2 [Member]
Exercise price (in dollars per share) | $ / shares	$ 2.20
Number of warrants (in shares) | shares	860,216
Common Stock Warrants Related to Private Placement Series A [Member]
Exercise price (in dollars per share) | $ / shares	$ 0.7949	[1]
Number of warrants (in shares) | shares	22,589,410
Common Stock Warrants Related to Private Placement Series B [Member]
Exercise price (in dollars per share) | $ / shares	$ 0.7949
Number of warrants (in shares) | shares	22,589,401

[1] These warrants expire on the date that is the later of: (i) 15 months from the date an increase in the number of authorized shares of common stock is effected (which occurred on January 17, 2023), or (ii) one month after the public announcement of the topline Phase 3 platinum-resistant ovarian cancer PROC data.