Note 13 - Subsequent Events

12 Months Ended

Dec. 31, 2018

Notes to Financial Statements

Subsequent Events [Text Block]

NOTE

1

3

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SUBSEQUENT EVENTS

In

November 2018,

the Company entered into an At Market Issuance Sales Agreement under which the Company could issue and sell shares of its common stock having an aggregate offering price of up to

$25

million from time to time in an “at-the-market” offering (the

“November 2018

ATM Offering”). From

January 1, 2019,

to

February 28, 2019,

the Company has issued

782,814

shares of common stock in the

November 2018

ATM Offering for gross proceeds of

$8.08

million and aggregate net proceeds of approximately

$7.92

million.

In

March 2019,

the Company entered into option agreements with parties holding

95%

of its Convertible Senior Notes that allow the Company, at its sole option, at any time prior to

December 5, 2019,

to extend the maturity date of the Convertible Senior Notes to

September 5, 2021