Non-cash stock-based compensation (Tables)

6 Months Ended

Jun. 30, 2023

Statement [Line Items]

Summary of Number of Shares Outstanding and Weighted Average Grant Date Fair Value

Information on free shares activity follows:

	Number of Free shares Outstanding			Weighted-Average Grant Date Fair Value
Unvested balance of December 31, 2021		922,701			14.15	€
Granted		354,770			2.79	€
Vested		(191,658	)		17.96	€
Cancelled		(176,700	)		13.99	€
Unvested balance as of December 31, 2022		909,113			11.18	€
Granted		342,900			3.08	€
Vested
Cancelled		(36,112	)		11.10	€
Unvested balance as of June 30, 2023		1,215,901			8.90	€

Stock options [member]

Statement [Line Items]

Summary of Information on Stock Option Activity

Information on stock option activity follows:

	Options Exercisable		Weighted-Average Exercise Price Per Share			Options Outstanding			Weighted-Average Exercise Price Per Share			Remaining Average Useful Life
Balance as of December 31, 2021		7,566,679		24.78	€		9,159,794			23.50	€		5.3	y
Granted				-			828,549			4.18	€
Exercised				-
Forfeited or Expired				-			(1,201,079	)		18.85	€
Balance as of December 31, 2022		7,400,519		24.58	€		8,787,264			22.31	€		4.6	y
Granted				-			1,835,411			2.86	€
Exercised				-			-			-
Forfeited or Expired				-			(22,638	)		18.29	€
Balance as of June 30, 2023		7,800,007		23.84	€		10,600,037			18.95	€		5.1	y

Summary of assumptions Vesting Details

The weighted-average fair values of stock options granted and the assumptions used for the Black-Scholes option pricing model were as follows:

	2022	2023
Weighted-Average fair values of stock options granted	1.31€	1.65€
Assumptions:
Risk-free interest rate	0.00% - 2.49%	2.45% - 2.75%
Share entitlement per options	1	1
Exercise price	2.09€ - 7.22€	1.74€ - 3.17€
Grant date share fair value	1.91€-6.74€	1.70€-3.09€
Expected volatility	58.7% - 62.5%	63.7% - 64.4%
Expected term (in years)	6.03 - 6.15	6.03 - 6.15
Vesting conditions	Performance or Service	Performance or Service
Vesting period	Graded	Graded

Non Employee Warrants [Member]

Statement [Line Items]

Summary of Information on Stock Option Activity

Information on non-employee warrants activity follows:

	Warrants Exercisable		Weighted-Average Exercise Price Per Share			Warrants Outstanding		Weighted-Average Exercise Price Per Share			Remaining Average Useful Life
Balance as of December 31, 2021		896,225		27.18	€		896,225		27.18	€		4.3	y
Granted
Exercised
Forfeited or Expired
Balance as of December 31, 2022		896,225		27.18	€		896,225		27.18	€		3.3	y
Granted
Exercised
Forfeited or Expired
Balance as of June 30, 2023		896,225		27.18	€		896,225		27.18	€		2.8	y