A summary of stock option activity is presented below (in thousands, except per share and contractual life data).

A summary of stock option activity is presented below (in thousands, except per share and contractual life data):

					Weighted
			Weighted		Average
			Average		Remaining
			Exercise		Contractual
	Number of		Price		Life
	Shares		Per Share		(in Years)
Options outstanding as of December 31, 2025		8,366	$	2.23		6.09
Granted		1,346	$	1.27
Exercised		(97)	$	1.27
Forfeited or expired		(494)	$	2.22
Options outstanding, vested and expected to vest as of September 30, 2026		9,121	$	2.10		6.12
Options exercisable as of September 30, 2026		6,289	$	2.47		4.97

The following table summarizes total stock-based compensation expense for stock options and RSUs, which is included in the statements of operations (in thousands):

The following table summarizes total stock-based compensation expense for stock options and RSUs, which is included in the condensed consolidated statements of operations (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2026		2025		2026		2025
Research and development	$	195	$	227	$	497	$	638
General and administrative		183		49		506		379
Total stock-based compensation expense	$	378	$	276	$	1,003	$	1,017

Summary of Restricted Stock Units Grant using the Monte Carlo Simulation model

The assumptions used to estimate the fair value of the performance-based restricted stock units granted during the nine months ended September 30, 2026 and 2025 was valued using a Monte Carlo simulation were as follows:

	Nine Months Ended September 30,
	2026	2025
RSUs Granted	292,500	292,500
Valuation date stock price	$1.31	$1.03
Risk-free interest rate	4.28%	3.99%
Expected dividend yield	0%	0%
Expected volatility	100%	100%

Simulation term

4 Years