424B5 1 sprb-424b5-2026-april.htm 424B5 424B5

Filed Pursuant to Rule 424(b)(5)
Registration No. 333-291152

The information in this preliminary prospectus supplement and the accompanying prospectus is not complete and may be changed. A registration statement relating to these securities has been filed with the Securities and Exchange Commission and is effective. This preliminary prospectus supplement and the accompanying prospectus are not an offer to sell these securities, and we are not soliciting offers to buy these securities in any jurisdiction where the offer or sale is not permitted.

SUBJECT TO COMPLETION, DATED APRIL 20, 2026

PRELIMINARY PROSPECTUS SUPPLEMENT

(To Prospectus Dated October 29, 2025)

Common Stock

Pre-Funded Warrants to Purchase Shares of Common Stock

We are offering shares of our common stock, par value $0.0001 per share, or in lieu of common stock to certain investors that so choose, pre-funded warrants to purchase shares of our common stock. The purchase price of each pre-funded warrant equals the price per share at which shares of our common stock are being sold to the public in this offering, minus $0.01, and the exercise price of each pre-funded warrant is $0.01 per share. We are also offering shares of our common stock that are issuable from time to time upon the exercise of the pre-funded warrants.

There is no established public trading market for the pre-funded warrants, and we do not expect a market to develop. We do not intend to apply for listing of the pre-funded warrants on the Nasdaq Capital Market or other securities exchange or nationally recognized trading system. Without an active trading market, the liquidity of the pre-funded warrants will be limited.

Our common stock is listed on the Nasdaq Capital Market under the symbol “SPRB.” The last reported sale price of our common stock on the Nasdaq Capital Market on April 17, 2026 was $70.30 per share.

Investing in our securities involves a high degree of risk. See “Risk Factors” beginning on page S-7 of this prospectus supplement, page 6 of the accompanying prospectus and under similar headings in the documents incorporated by reference into this prospectus supplement and the accompanying prospectus.

We are a “smaller reporting company” under applicable Securities and Exchange Commission rules and as such, have elected to comply with reduced public company reporting requirements. See “Prospectus Supplement Summary — Implications of Being a Smaller Reporting Company.”

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus supplement or the accompanying prospectus is truthful or complete. Any representation to the contrary is a criminal offense.


		Per Share		Per Pre-Funded Warrant		Total
Public Offering Price	$		$		$
Underwriting Discounts and Commissions(1)	$		$		$
Proceeds to Spruce Biosciences, Inc. before expenses	$		$		$

(1) We have agreed to reimburse the underwriters for certain expenses. See “Underwriting” beginning on page S-21 of this prospectus supplement for additional information regarding underwriter compensation.

Delivery of shares of common stock and pre-funded warrants is expected to be made on or about , 2026.

We have granted the underwriters an option for a period of 30 days to purchase up to an additional of shares of our common stock at the public offering price, less the underwriting discounts and commissions. If the underwriters exercise the option in full, the total underwriting discounts and commissions payable by us will be $ , and the total proceeds to us, before expenses, will be $ .

Joint Bookrunning Managers

Leerink Partners Guggenheim Securities Oppenheimer & Co.

Co-Managers

Jones Craig-Hallum

Prospectus Supplement dated , 2026


Prospectus Supplement
	Page

ABOUT THIS PROSPECTUS SUPPLEMENT	S-1

SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS	S-2

PROSPECTUS SUPPLEMENT SUMMARY	S-4

THE OFFERING	S-5

RISK FACTORS	S-7

USE OF PROCEEDS	S-10

DIVIDEND POLICY	S-11

DILUTION	S-12

DESCRIPTION OF SECURITIES WE ARE OFFERING	S-14

Material U.S. Federal Income Tax Consequences to Non-U.S. Holders OF our COMMON STOCK and pre-funded warrants	S-17

UNDERWRITING	S-21

LEGAL MATTERS	S-27

EXPERTS	S-27

WHERE YOU CAN FIND MORE INFORMATION	S-27

INCORPORATION OF CERTAIN INFORMATION BY REFERENCE	S-28


Prospectus
	Page

ABOUT THIS PROSPECTUS	1

PROSPECTUS SUMMARY	2

RISK FACTORS	6

SELECTED FINANCIAL DATA REFLECTING REVERSE STOCK SPLIT	7

SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS	9

USE OF PROCEEDS	10

DESCRIPTION OF CAPITAL STOCK	11

DESCRIPTION OF DEBT SECURITIES	15

DESCRIPTION OF WARRANTS	22

LEGAL OWNERSHIP OF SECURITIES	25

PLAN OF DISTRIBUTION	29

LEGAL MATTERS	32

EXPERTS	32

WHERE YOU CAN FIND MORE INFORMATION	32

INCORPORATION OF CERTAIN INFORMATION BY REFERENCE	32


Common stock offered by Spruce		shares
Pre-funded warrants offered by Spruce		We are also offering, in lieu of common stock to certain investors that so choose, pre-funded warrants to purchase shares of our common stock. The purchase price of each pre-funded warrant equals the price per share at which the shares of our common stock are being sold to the public in this offering, minus $0.01, which is the exercise price of each pre-funded warrant per share. The pre-funded warrants do not expire and each pre-funded warrant will be exercisable at any time after the date of issuance of such pre-funded warrant, subject to an ownership limitation. See “Description of Securities We Are Offering—Pre-Funded Warrants” on page S-14 of this prospectus supplement. This prospectus supplement also relates to the offering of the shares of our common stock issuable upon exercise of the pre-funded warrants.
Common stock to be outstanding after this offering		shares of common stock (or shares of common stock if the underwriters exercise in full their option to purchase additional shares) in each case assuming no exercise of any pre-funded warrants issued in this offering.
Option to purchase additional shares		We have granted the underwriters an option to purchase up to an additional shares of our common stock from us. The underwriters can exercise this option, in whole or in part, at any time within 30 days from the date of this prospectus supplement.
Use of proceeds		We estimate that the net proceeds to us from this offering, after deducting underwriting discounts and commissions and estimated offering expenses payable by us, will be approximately $ million, or approximately $ million if the underwriters exercise their option to purchase additional shares from us in full. We will receive only nominal additional proceeds from any exercise of pre-funded warrants. We intend to use the net proceeds from this offering to advance the Company’s pre-commercial and launch activities, for planned clinical trials, and for working capital, capital expenditures and other general corporate purposes. See “Use of Proceeds” on page S-10 of this prospectus supplement.
Risk factors		Investing in our securities involves a high degree of risk. You should read the “Risk Factors” section of this prospectus supplement beginning on page S-7, page 6 of the accompanying prospectus, and in the documents incorporated by reference herein or therein, for a discussion of factors to consider carefully before deciding to invest in our securities.
Nasdaq Capital Market symbol		“SPRB”



Public offering price per share			$
Net tangible book value per share as of December 31, 2025	$	30.99
Increase in net tangible book value per share attributable to investors purchasing our common stock and pre-funded warrants in this offering

As adjusted net tangible book value per share after this offering

Dilution per share to new investors			$



Underwriter	Number of Shares	Number of Pre-Funded Warrants
Leerink Partners LLC
Guggenheim Securities, LLC
Oppenheimer & Co. Inc.
JonesTrading Institutional Services LLC
Craig-Hallum Capital Group LLC
Total


	Year Ended December 31,
	2024			2023
Net loss	$	(53,036	)	$	(47,919	)
Net loss per share, basic and diluted	$	(1.29	)	$	(1.24	)
Weighted-average shares of common stock outstanding, basic and diluted		41,264,948			38,510,220
Shares of common stock outstanding at year end		42,231,285			41,029,832


	Three Months Ended March 31,
	2025			2024
Net loss	$	(14,041	)	$	(11,625	)
Net loss per share, basic and diluted	$	(0.32	)	$	(0.28	)
Weighted-average shares of common stock outstanding, basic and diluted		43,944,946			41,096,231
Shares of common stock outstanding at period end		42,231,285			41,154,799

ABOUT THIS PROSPECTUS SUPPLEMENT

SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

PROSPECTUS SUPPLEMENT SUMMARY

Company Overview

Corporate Information

Implications of Being a Smaller Reporting Company

RISK FACTORS

USE OF PROCEEDS

LEGAL MATTERS

EXPERTS

WHERE YOU CAN FIND MORE INFORMATION

INCORPORATION OF CERTAIN INFORMATION BY REFERENCE

This prospectus may not be used to consummate a sale of any securities unless accompanied by a prospectus supplement.

ABOUT THIS PROSPECTUS

THIS PROSPECTUS MAY NOT BE USED TO CONSUMMATE A SALE OF SECURITIES UNLESS IT IS ACCOMPANIED BY A PROSPECTUS SUPPLEMENT.

PROSPECTUS SUMMARY

Company Overview

Implications of Being an Emerging Growth Company and Smaller Reporting Company

Corporate Information

The Securities We May Offer

This prospectus may not be used to consummate a sale of securities unless it is accompanied by a prospectus supplement.

RISK FACTORS

SELECTED FINANCIAL DATA REFLECTING REVERSE STOCK SPLIT

Reverse Stock Split

SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

USE OF PROCEEDS

DESCRIPTION OF CAPITAL STOCK

General

Common Stock

Preferred Stock

Anti-Takeover Provisions

Choice of Forum

Exchange Listing

Transfer Agent and Registrar

DESCRIPTION OF WARRANTS

General

Exercise of Warrants

Governing Law

Enforceability of Rights by Holders of Warrants

LEGAL OWNERSHIP OF SECURITIES

Book-Entry Holders

Street Name Holders

Legal Holders

Special Considerations for Indirect Holders

Global Securities

Special Considerations for Global Securities

Special Situations When a Global Security Will Be Terminated

PLAN OF DISTRIBUTION

LEGAL MATTERS

EXPERTS

WHERE YOU CAN FIND MORE INFORMATION

INCORPORATION OF CERTAIN INFORMATION BY REFERENCE

SEC Form 424B5 filed by Spruce Biosciences Inc.