In January 2021, the Company completed an S-1 offering (the “January 2021 Offering”) of an aggregate of 580,000 shares of common stock, pre-funded warrants to purchase up to 120,000 shares of its common stock, and common stock warrants to purchase up to an aggregate of 700,000 shares of common stock. To the extent that an investor determines, at their sole discretion, that they would beneficially own in excess of the Beneficial Ownership Limitations (or as such investor may otherwise choose), in lieu of purchasing shares of common stock and common stock warrants, such investor could have elected to purchase Pre-Funded Warrants and Common Warrants at the pre-funded purchase price in lieu of the shares of common stock and common stock warrants in such a manner to result in the same aggregate purchase price being paid by such investor to the Company. The combined purchase price of one share of common stock and the accompanying common stock warrant was $20.00, and the combined purchase price of one pre-funded warrant and accompanying common stock warrant was $19.998. The common stock warrants are exercisable for five (5) years at an exercise price of $20.00 per share. The pre-funded warrants were immediately exercisable at an exercise price of $0.002 per share and were exercisable at any time until all of the pre-funded warrants are exercised in full. Placement agent warrants were issued to purchase up to 35,000 shares of common stock, are immediately exercisable for an exercise price of $25.00 per share, and are exercisable for five (5) years following the date of issuance. The Company received gross proceeds of $14.0 million and incurred placement agent’s fees and other offering expenses of approximately $1.9 million.

The common stock warrants and placement agent warrants were valued at $7.2 million and $0.3 million, respectively, using the Black-Scholes option pricing model based on the following assumptions: expected volatility 80.08%, risk-free interest rate 0.38%, expected dividend yield 0%, and an expected term of 5.0 years.

As of September 30, 2023, a total of 336,060 warrants issued in the January 2021 Offering to purchase shares of common stock have been exercised and the Company issued 336,060 shares of its common stock. The Company received gross proceeds of approximately $6.8 million.

As of September 30, 2023, the Company had 387,565 shares and 11,375 shares of common stock reserved for issuance pursuant to the warrants and placement agent’s warrants, respectively, issued by the Company in the January 2021 Offering, at an exercise price of $20.00 per share and $25.00 per share, respectively.

In June 2021, the Company completed a registered direct offering (the “June 2021 Offering”) of an aggregate of 298,865 shares of common stock, together with accompanying warrants to purchase up to an aggregate of 239,093 shares of common stock, at a public offering price of $22.00 per share. The accompanying warrants permit the investor to purchase additional shares equal to 80% of the number of shares of the Company’s common stock purchased by the investor. The warrants have an exercise price of $20.00 per share, are immediately exercisable, and expire five and a half (5.5) years following the date of issuance. In addition, the Company’s placement

agent was issued compensatory warrants equal to 5.0%, or 14,946 shares, of the aggregate number of common stock sold in the offering, which are immediately exercisable for an exercise price of $27.50 and expire five (5) years following the date of issuance on June 7, 2026. The Company received gross proceeds of $6.6 million and incurred cash-based placement agent fees and other offering expenses of approximately $0.9 million.

The warrants and placement agent warrants were valued at $3.0 million and $0.2 million, respectively, using a Black-Scholes option pricing model with the following assumptions: expected volatility 81.44% and 80.15%, risk-free interest rate 0.88% and 0.77%, expected dividend yield 0% and 0%, and an expected term of 5.5 years or 5.0 years, respectively.

As of September 30, 2023, no warrants associated with the June 2021 Offering have been exercised.

As of September 30, 2023, the Company had 90,910 shares and 14,946 shares of common stock reserved for issuance pursuant to the warrants and placement agent’s warrants, respectively, issued by the Company in the June 2021 Offering, at an exercise price of $20.00 per share and $27.50 per share, respectively. In connection with the July 2022 Offering, the Company agreed to amend warrants, by reducing the exercise price and extending the expiration date, to purchase up to an aggregate of 148,183 shares of common stock of the Company that were originally issued to the investor in the June 2021 Offering. Refer to July 2022 Offering overview below for accounting treatment for the amended warrants.

In December 2021, the Company completed a registered direct offering (the “December 2021 Offering”) of an aggregate of 411,764 shares of common stock and 411,766 warrants to purchase up to 411,766 shares of common stock, at a public offering price of $8.50 per share. The accompanying warrants permit the investor to purchase additional shares equal to approximately the same number of shares of the Company’s common stock purchased by the investor. The warrants have an exercise price of $8.50 per share, may be exercised any time on or after 6 months and one (1) day after the issuance date, and expire five and a half (5.5) years following the date of issuance. In addition, the Company’s placement agent was issued compensatory warrants equal to 5.0%, or 20,590 shares, of the aggregate number of shares of common stock sold in the offering, which are immediately exercisable for an exercise price of $10.626 and expire five and a half (5.5) years following the date of issuance on June 21, 2027. The Company received gross proceeds of $3.5 million and incurred cash-based placement agent fees and other offering expenses of approximately $0.5 million.

The placement agent warrants, which are recorded as a component of stockholders’ equity, were valued at an aggregate $0.1 million using the Black-Scholes option pricing model based on the following assumptions: expected volatility of 79.81%, risk-free interest rate of 1.21%, expected dividend yield of 0% and an expected term of 5.5 years.

As of September 30, 2023, no warrants associated with the December 2021 Offering have been exercised.

As of September 30, 2023, the Company had 164,707 shares and 20,590 shares of common stock reserved for issuance pursuant to the warrants and placement agent’s warrants, respectively, issued by the Company in the December 2021 Offering, at an exercise price of $8.50 per share and $10.626 per share, respectively. In connection with the July 2022 Offering, the Company agreed to amend warrants, by reducing the exercise price and extending the expiration date, to purchase up to an aggregate of 247,059 shares of common stock of the Company that were originally issued to the investor in the December 2021 Offering. Refer to July 2022 Offering overview below for accounting treatment for the amended warrants.

On July 12, 2022, the Company entered into a Securities Purchase Agreement (the “July 2022 Purchase Agreement”) with a single healthcare-focused institutional investor for the sale by the Company of (i) a pre-funded warrant to purchase up to 1,774,309 shares of Common Stock (the “Pre-Funded Warrant”), (ii) a Series A warrant to purchase up to an aggregate of 1,774,309 shares of common stock (the “Series A Warrant”), and (iii) a Series B warrant to purchase up to an aggregate of 1,774,309 shares of common stock (the “Series B Warrant,” and together with the Pre-Funded Warrant and the Series A Warrant, the “Warrants”), in a private placement offering (the “Offering”). The combined purchase price of one Pre-Funded Warrant and accompanying Series A Warrant and accompanying Series B Warrant was $2.818.

Subject to certain ownership limitations, the Series A Warrant became exercisable immediately after the issuance date at an exercise price equal to $2.568 per share of common stock, subject to adjustments as provided under the terms of the Series A Warrant, and has a term of five and a half (5.5) years from the issuance date. Subject to certain ownership limitations, the Series B Warrant became exercisable immediately after the issuance date at an exercise price equal to $2.568 per share of common stock, subject to adjustments as provided under the terms of the Series B Warrant, and has a term of one and a half (1.5) years from the issuance date. Subject to certain ownership limitations described in the Pre-Funded Warrant, the Pre-Funded Warrant was immediately exercisable at an exercise

price of $0.0001 per share of common stock any time until all of the Pre-Funded Warrant is exercised in full. As of September 30, 2023, the Pre-Funded Warrant to purchase up to an aggregate of 1,774,309 shares of common stock had been fully exercised and the Company issued 1,774,309 shares of common stock.

The Company also agreed to amend certain warrants to purchase up to an aggregate of 447,800 shares of common stock of the Company that were issued to the investor in the private placement in November 2020, June 2021 and December 2021 with exercise prices ranging from $8.50 to $34.00 per share and expiration dates ranging from May 18, 2026 to June 21, 2027, so that such warrants have a reduced exercise price of $2.568 per share and expiration date of five and a half (5.5) years following the closing of the private placement, for an additional offering price of $0.0316 per amended warrant. The incremental fair value resulting from the modifications to the warrants was adjusted against the gross proceeds from the offering as an equity issuance cost.

The gross proceeds to the Company were approximately $5 million, before deducting the placement agent’s fees and other offering expenses, and excluding the proceeds, if any, from the exercise of the Series A Warrant, the Series B Warrant, and amended warrants.

The Series A warrants and placement agent warrants were valued at $3.8 million and $0.2 million, respectively, using the Black-Scholes option pricing model based on the following assumptions: expected volatility 79.28%, risk-free interest rate 3.06%, expected dividend yield 0%, and an expected term of 5.5 years.

The Series B warrants were valued at $2.3 million using the Black-Scholes option pricing model based on the following assumptions: expected volatility 74.25%, risk-free interest rate 3.16%, expected dividend yield 0%, and an expected term of 1.5 years.

The amended warrants were valued at $1.0 million using the Black-Scholes option pricing model based on the following assumptions: expected volatility 79.28%, risk-free interest rate 3.06%, expected dividend yield 0%, and an expected term of 5.5 years. The estimated fair value of the original warrants immediately prior to the warrant amendments was $0.5 million using Black-Scholes option pricing model based on the following assumptions: expected volatility ranging from 81.21 – 83.34%, risk-free interest rates of 3.06 – 3.16%, expected dividend yield 0%, and an expected terms of 3.84 – 4.94 years. The warrant modifications resulted in an estimated value of $0.5 million, measured as the incremental fair value of the amended warrants, and was adjusted against the gross proceeds from the offering.

As of September 30, 2023, no warrants associated with the July 2022 Purchase Agreement have been exercised.

As of September 30, 2023, the Company had 3,996,418 shares and 124,202 shares of common stock reserved for issuance pursuant to the warrants and placement agent’s warrants, respectively, issued by the Company in the July 2022 Purchase Agreement, at an exercise price of $2.568 per share and $3.5225 per share, respectively.

As of September 30, 2023, warrants to purchase 68 shares of common stock with an exercise price of $1,486.00 per share that were issued by Conatus in connection with obtaining financing in 2016 expired unexercised on July 3, 2023.

See warrant discussion above in connection with the January 2021 Offering, the June 2021 Offering, the December 2021 Offering, and the July 2022 Offering.

On December 18, 2017, Private Histogen established the Histogen Inc. 2017 Stock Plan (the “2017 Plan”). Under the 2017 Plan, Private Histogen was authorized to issue a maximum aggregate of 41,861 shares of common stock with adjustments for unissued or forfeited shares under the predecessor plan (the Histogen Inc. 2007 Stock Plan). In April 2019, Private Histogen amended the 2017 Plan, which increased the number of common stock available for grants by 16,336 shares. The 2017 Plan permitted the issuance of incentive stock options (“ISOs”), non-statutory stock options (“NSOs”), and Stock Purchase Rights. NSOs could be granted to employees, directors, or consultants, while ISOs could be granted only to employees. Options granted vest over a maximum period of four years and expire ten years from the date of grant. In connection with the closing of the Merger, no further awards were made under the 2017 Plan and any cancelled, forfeited or expired options were not made available for granting. As of September 30, 2023, 4,662 fully vested options remain outstanding under the 2017 Plan.

In May 2020, in connection with the closing of the Merger, the Company’s stockholders approved the Company’s 2020 Incentive Award Plan (the “2020 Plan”). The maximum number of shares of the Company’s common stock available for issuance under the 2020 Plan equals the sum of (a) 42,500 shares; (b) any shares of common stock of the Company which are subject to awards under the Conatus 2013 Equity Incentive Plan (the “Conatus 2013 Plan”) as of the effective date of the 2020 Plan which become available for issuance under the 2020 Plan after such date in accordance with its terms; and (c) an annual increase on the first day of each calendar year beginning with the January 1 of the calendar year following the effectiveness of the 2020 Plan and ending with the last January 1 during the initial ten-year term of the 2020 Plan, equal to the lesser of (i) five percent of the number of shares of the Company’s common stock outstanding (on an as-converted basis) on the final day of the immediately preceding calendar year, and (ii) such lesser number of shares of the Company’s common stock as determined by the Company’s Board.

On June 20, 2023, the Company held its 2023 Annual Meeting of Stockholders (the “Annual Meeting”) at which time the stockholders approved an amendment to the Company’s 2020 Plan to increase the number of shares authorized for issuance thereunder by 500,000 shares, as previously approved by the Board.

The following summarizes activity related to the Company’s stock options under the 2017 Plan and the 2020 Plan for the nine months ended September 30, 2023:


	Options Outstanding			Weighted- average Exercise Price		Weighted- average Remaining Contractual Term (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2022		113,279		$	21.30		8.09	$	—
Granted		472,454			0.94
Cancelled / Forfeited		(371,301	)		5.27
Outstanding at September 30, 2023		214,432		$	4.20		9.29	$	—
Vested and exercisable at September 30, 2023		22,912		$	30.56		7.16	$	—

The following weighted-average assumptions were used to calculate the fair value of awards granted to employees, non-employees and directors:


	Three Months Ended September 30,						Nine Months Ended September 30,
	2023			2022			2023			2022
Expected volatility		—	%		—	%		93.53	%		78.95	%
Risk-free interest rate		—	%		—	%		3.91	%		2.14	%
Expected option life (in years)		—			—			6.03			6.02
Expected dividend yield		—	%		—	%		—	%		—	%

Additionally, in connection with the closing of the Merger, no further awards will be made under the Conatus 2013 Plan. As of September 30, 2023, 4,487 fully vested options remain outstanding under the Conatus 2013 Plan with a weighted average exercise price of $740.10 per share.

On November 8, 2021, the Company granted 23,423 restricted stock units to the Company’s then Interim Chief Executive Officer, Chief Financial Officer, and Senior Vice President of Technical Operations. The fair value of the RSUs was $14.58 per share, which was the closing market price of the Company’s common stock on the date of grant. The RSUs vest in full upon the earlier of (1) 12 months following the grant date and (2) a change of control of the Company, as defined in the Company’s 2020 Plan, subject to continued service to the Company. Prior to RSU vesting, on November 7, 2022, the Company and the RSU recipients mutually agreed to enter into RSU Cancellation Agreements such that the RSU awards are cancelled and no longer outstanding.

On March 10, 2023, the Company approved stock option grants to purchase 111,063 shares of the Company’s common stock to certain officers and employees as part of an annual award grant. Because the Company did not have sufficient shares available under the 2020

Plan at the time of approval, these shares were subject to forfeiture in the event that the shares available pursuant to the plan were not increased prior to the one-year anniversary and vesting of the award by an amount required to be available for issuance for all outstanding stock awards containing the forfeiture condition (“Forfeiture Stock Option Grants”). The Company had a conditional obligation to increase the shares available for issuance under the stock option plans before these Forfeiture Stock Option Grants can be granted at which time the Company would begin to recognize compensation costs from the inception date of the award through grant date. On June 20, 2023, the Company held its Annual Meeting at which the stockholders approved an amendment to the Company’s 2020 Plan to increase the number of shares authorized for issuance thereunder by 500,000 shares, which met the Company’s conditional obligation to increase the shares available for issuance. The Forfeiture Stock Options Grants were granted as of June 20, 2023.

As such, during the three and nine months ended September 30, 2023, the Company began recognizing compensation expense for the Forfeiture Stock Option Grants dating back to the March 10, 2023 inception date of the grant awards.

On September 18, 2023, the Company announced the Board approved a Plan of Dissolution and implemented a reduction in its workforce effective September 30, 2023. The reduction in workforce resulted in the forfeiture of 281,934 stock options granted under the 2020 Plan to certain officers and employees which did not meet certain vesting criteria.

On March 10, 2023, the Company entered into Stock Option Cancellation Agreements with certain officers and employees (the “Option holders”), pursuant to which such individuals surrendered and cancelled 69,045 stock options with a weighted average price of $17.92 per share to purchase shares of the Company’s common stock (the “Cancelled Stock Options”). Pursuant to the terms of the Stock Option Cancellation Agreements, the Company agreed to pay each of the option holders a lump sum cash payment of $250 in exchange for the agreement to cancel the aforementioned stock options. The Company determined that because the Cancelled Stock Options were cancelled in exchange of cash consideration, the cash payments are considered partial settlements of the original awards and the cancellation should be accounted for as a repurchase of outstanding equity. The Company also determined that cash paid in exchange of cancellation was less than the fair value of the original awards and the stock options were probable of vesting pursuant to their original terms. Therefore, the Company recorded previously unrecognized compensation costs related to the Cancelled Stock Options of approximately $0 and $0.4 million during the three and nine months ended September 30, 2023, respectively, on the accompanying condensed consolidated statements of operations.

On February 23, 2023, the Company issued 106,793 stock options to its newly appointed Executive Vice President and Chief Scientific Officer as an inducement grant outside of the Company’s equity incentive plans in accordance with Nasdaq Listing Rule 5635(c)(4). In accordance with the award agreement, 25% of the options vest on the first anniversary of the employee’s hire date, on February 1, 2024, and then ratably over the remaining 36 months. Based on the terms being similar to standard grants as awarded under the 2020 Plan, the Company applied ASC 718 accounting basis for the recognition of share-based compensation expense. The inducement grant was valued at $0.1 million using the Black-Scholes option pricing model based on the following assumptions: expected volatility 91.65%, risk-free interest rate 4.06%, expected dividend yield 0%, and an expected term of 6.08 years. On September 18, 2023, the Company announced the Board approved a Plan of Dissolution and implemented a reduction in its workforce effective September 30, 2023. The reduction in workforce also resulted in the forfeiture of 106,793 inducement grant stock options which did not meet certain vesting criteria. As of September 30, 2023, no inducement grant options were vested and none are outstanding.

The compensation cost, including the inducement grant expense, that has been included in the accompanying condensed consolidated statements of operations for all stock-based compensation arrangements is detailed as follows (in thousands):


	Three Months Ended September 30,					Nine Months Ended September 30,
	2023			2022		2023		2022
General and administrative	$	6		$	121	$	415	$	388
Research and development		(13	)		12		29		25
Total	$	(7	)	$	133	$	444	$	413

As of September 30, 2023, total unrecognized compensation cost related to unvested options was approximately $0.1 million which is expected to be recognized over a weighted-average period of 2.87 years.

Common stock reserved for future issuance is as follows:


	As of September 30,
	2023		2022
Common stock warrants		4,876,571		4,876,639
Common stock options issued and outstanding under stock plans		218,919		129,006
Common stock available for issuance under stock plans		708,768		94,524
Total		5,804,258		5,100,169