Crescent Biopharma

424B3 1 crescentbiopharma-424b3.htm 424B3 Crescent Biopharma - 424b3

Filed Pursuant to Rule 424(b)(3)

Registration No. 333-292600

Prospectus Supplement No. 4

(To Prospectus dated March 3, 2026)

19,580,843 Shares

Ordinary Shares

Offered by the Selling Securityholders

This prospectus supplement updates, amends and supplements the prospectus dated March 3, 2026 (the “Prospectus”), relating to the proposed resale or other disposition by the selling securityholders identified in the Prospectus of up to an aggregate of 19,580,843 ordinary shares with a par value of US$0.001 per share (“Ordinary Shares”) of Crescent Biopharma, Inc. (the “Company”), consisting of (i) 13,534,837 outstanding Ordinary Shares issued pursuant to the Private Placement (as defined in the Prospectus), (ii) 131,434 Ordinary Shares issuable upon the exercise of pre-funded warrants issued pursuant to the Private Placement and (iii) 1,387,866 outstanding Ordinary Shares, 1,636,706 Ordinary Shares issuable upon the exercise of pre-funded warrants, and 2,890,000 Ordinary Shares issuable upon the conversion of Series A non-voting convertible preferred shares, in each case, held by Fairmount Healthcare Fund II L.P. as of immediately prior to the closing of the Private Placement, which forms a part of our Registration Statement on Form S-1 (Registration No. 333-292600).

This prospectus supplement is being filed to update, amend and supplement the Prospectus with the information contained in our Quarterly Report on Form 10-Q for the quarterly period ended June 30, 2026, filed with the Securities and Exchange Commission on July 30, 2026, and set forth below.

This prospectus supplement is not complete without the Prospectus. This prospectus supplement should be read in conjunction with the Prospectus, which is to be delivered with this prospectus supplement, and is qualified by reference thereto, except to the extent that the information in this prospectus supplement updates or supersedes the information contained in the Prospectus. Please keep this prospectus supplement with your Prospectus for future reference.

Our Ordinary Shares are listed on the Nasdaq Stock Market (“Nasdaq”) under the symbol “CBIO”. On July 29, 2026, the closing sale price of our Ordinary Shares was $14.77 per share.

INVESTING IN OUR SECURITIES INVOLVES RISKS THAT ARE DESCRIBED IN THE “RISK FACTORS” SECTION BEGINNING ON PAGE 9 OF THE PROSPECTUS.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the accuracy or adequacy of this prospectus supplement or the Prospectus. Any representation to the contrary is a criminal offense.

The date of this prospectus supplement is July 30, 2026.

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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

________________________________

FORM 10-Q

________________________________

(Mark One)


x			QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the quarterly period ended June 30, 2026


o			TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from _________ to _________

Commission file number 001-36177

________________________________

Crescent Biopharma, Inc.

(Exact name of registrant as specified in its charter)

________________________________


Cayman Islands									06-1686563
(State or other jurisdiction of incorporation or organization)									(I.R.S. Employer Identification No.)

300 Fifth Avenue
Waltham, MA									02451
(Address of Principal Executive Offices)									(Zip Code)

Registrant’s telephone number, including area code: (617) 430-5595

Securities registered pursuant to Section 12(b) of the Act:


Title of each class	Trading Symbol(s)	Name of each exchange on which registered
Ordinary Shares, $0.001 par value per share	CBIO	The Nasdaq Capital Market

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.

Yes x No o

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§ 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files).

Yes x No o

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and "emerging growth company" in Rule 12b-2 of the Exchange Act.

Large accelerated filer

Accelerated filer

Non-accelerated filer

☒

Smaller reporting company

☒

Emerging growth company

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).

Yes o No ☒

As of July 27, 2026, there were 37,143,940 of the issuer’s ordinary shares outstanding.

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		Page No.

	F orward -looking Statements	ii

	S ummary Risk Factors	i ii

Part I	Financial Information	1

Item 1.	Financial Statements (Unaudited)	1

	Condensed Consolidated Balance Sheets (Unaudited)	1

	Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited)	2

	Condensed Consolidated Statements of Convertible Preferred Shares and Shareholders’ Equity (Deficit) (Unaudited)	3

	Condensed Consolidated Statements of Cash Flows (Unaudited)	4

	Notes to the Condensed Consolidated Financial Statements (Unaudited)	6

Item 2.	Management’s Discussion and Analysis of Financial Condition and Results of Operations	26

Item 3.	Quantitative and Qualitative Disclosures About Market Risk	39

Item 4.	Controls and Procedures	39

Part II	Other Information	40

Item 1.	Legal Proceedings	40

Item 1A.	Risk Factors	40

Item 2.	Unregistered Sales of Equity Securities and Use of Proceeds	85

Item 3.	Defaults Upon Senior Securities	85

Item 4.	Mine Safety Disclosures	85

Item 5.	Other Information	85

Item 6.	Exhibits	85

Signatures		87

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FORWARD-LOOKING STATEMENTS

This Quarterly Report on Form 10-Q contains “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended (the “Securities Act”) and Section 21E of the Securities Exchange Act of 1934, as amended (the “Exchange Act”).

All statements other than statements of historical facts contained in this Quarterly Report on Form 10-Q, are forward-looking statements, including, without limitation, statements regarding:

•the success, cost, timing and potential indications of our product development activities and clinical trials;

•our ability to advance clinical development of, and ultimately obtain approval from, the U.S. Food and Drug Administration (“FDA”) and other regulatory agencies in countries outside of the U.S. for our product candidates;

•our research and development plans and ability to identify and bring forward additional product candidates into preclinical and clinical development;

•the rate and degree of market acceptance of our product candidates, including our ability to successfully compete with existing therapies and therapies currently in development, and our expectations regarding the size of the commercial markets for our product candidates;

•our future marketing and sales programs;

•the scope of protection we are able to establish and maintain for intellectual property rights covering product candidates;

•our use of net proceeds from financing activities, including the availability of and our ability to obtain additional financing and to continue as a going concern;

•the effects of existing and future federal, state and foreign regulations and our expectations regarding the impact of macroeconomic conditions and geopolitical conflicts on our business and operations;

•the seeking and execution of joint development, licensing or distribution and collaboration and marketing arrangements with third parties;

•the period of time for which our existing cash and cash equivalents will enable us to fund our operations; and

•our relationship with Paragon Therapeutics, Inc., Fairmount Funds Management LLC, and Parascent Holding LLC.

Forward-looking statements generally relate to future events or our future financial or operating performance. The words “believe,” “may,” “will,” “potentially,” “estimate,” “continue,” “anticipate,” “predict,” “target,” “intend,” “could,” “would,” “should,” “project,” “plan,” “expect,” and similar expressions that convey uncertainty of future events or outcomes are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words.

These forward-looking statements are based on management’s current expectations, estimates, forecasts and projections about our business and the industry in which we operate. These statements are neither promises nor guarantees, but involve known and unknown risks, uncertainties and other important factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. Factors that may cause actual results to differ materially from current expectations include the initiation, execution and completion of clinical trials, uncertainties surrounding the timing of availability of data from our clinical trials, ongoing discussions with and actions by regulatory authorities, our development activities and those other factors we discuss in “Summary Risk Factors,” Part II, Item 1A. “Risk Factors,” and Part I, Item 2. “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and elsewhere in this Quarterly Report on Form 10-Q (“Form 10-Q”). You should read these risk factors and the other cautionary statements made in this report as being applicable to all related forward-looking statements wherever they appear in this report. The risk factors are not exhaustive and other sections of this report may include additional factors which could adversely impact our business and financial performance.

Drug development and commercialization involve a high degree of risk, and only a small number of research and development programs result in commercialization of a product. Preliminary and interim results from any trial and results in early-stage clinical trials may not be indicative of full results or results from later stage or larger scale clinical trials and do not ensure regulatory approval. Moreover, we operate in a very competitive and rapidly changing environment. New

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risk factors emerge from time to time, and it is not possible for our management to predict all risk factors nor can we assess the impact of all factors on our business or the extent to which any factor, or combination of factors, may cause actual results to differ materially from those contained in, or implied by, any forward-looking statements. Given these uncertainties, you should not rely on these forward-looking statements as predictions of future events. Except as required by law, we assume no obligation to update or revise these forward-looking statements for any reason, even if new information becomes available in the future.

As used in this Quarterly Report, unless the context suggests otherwise, “we,” “us,” “our,” “the Company,” “Crescent Biopharma, Inc.,” “Crescent,” “GlycoMimetics, Inc.,” “GlycoMimetics,” refers to Crescent Biopharma, Inc. and its consolidated subsidiaries, including Crescent Biopharma Operating Company LLC, taken as a whole.

iii

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Summary Risk Factors

Our business is subject to numerous risks and uncertainties, including those described in Part II, Item 1A. “Risk Factors” in this Quarterly Report on Form 10-Q. The principal risks and uncertainties affecting our business include the following:

Risks Related to Our Financial Condition and Capital Requirements

•We are a clinical-stage biotechnology company with a limited operating history on which to assess our business; we have not completed any clinical trials, and have no products approved for commercial sale.

•We have historically incurred losses and we anticipate that we will continue to incur losses for the foreseeable future.

•We have never generated revenue from product sales and may never be profitable.

•We may not be able to raise the capital that we need to support our business plans.

•Raising additional capital may cause additional dilution to our shareholders, restrict our operations, or require us to relinquish rights to our technologies or product candidates.

Risks Related to Clinical Development and Regulatory Approval

•Drug development and obtaining and maintaining regulatory approval for drug products is costly, time-consuming, and highly uncertain.

•We are substantially dependent on the success of our lead program, CR-001, and our current and anticipated clinical trials of such program may not be successful.

•We may not be able to meet requirements for the chemistry, manufacturing, and control of our programs.

•We face competition from entities that have developed or may develop programs for the diseases addressed by product candidates developed by us.

•The United States Food and Drug Administration (“FDA”) and comparable foreign regulatory approval processes are lengthy and time consuming and we may not be able to obtain or may be delayed in obtaining regulatory approvals for our product candidates.

•Disruptions at the FDA and other government agencies could negatively affect the review of our regulatory submissions, which could negatively impact our business.

•Even if we obtain regulatory approval, we will be subject to ongoing regulatory obligations.

•We may fail to achieve our projected development goals in the time frames we announce and expect.

Risks Related to Our Intellectual Property

•We do not currently own any issued patents and our patent portfolio is in-licensed from Paragon Therapeutics, Inc, (“Paragon”) and Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. (“Kelun”).

•Our ability to obtain and protect patent rights and protect other proprietary rights is uncertain.

•We may fail in obtaining or maintaining necessary rights to our programs.

•We may be subject to patent infringement claims or may need to file such claims.

•Our ability to protect our products may be impaired by changes to patent laws.

•Our patent protection could be reduced or eliminated for non-compliance with legal requirements.

•We may fail to identify or interpret relevant third-party patents.

•We may become subject to claims challenging the inventorship or ownership of our intellectual property.

•Patent terms may be inadequate to protect our competitive position of our programs.

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•Our technology licensed from Paragon and Kelun and any technology licensed from other third-parties in the future may be subject to retained rights.

•We may be unable to protect the confidentiality of our trade secrets and other proprietary information.

•We may become subject to litigation under the Biologics Price Competition and Innovation Act of 2010 (“BPCIA”) in connection with patent rights for our product candidates.

Risks Related to Our Reliance on Third Parties

•We currently and in the future expect to rely on agreements with third parties to develop our product candidates. If we are unable to maintain our current or future collaborations or licensing arrangements, or if our current or future collaborations or licensing arrangements are not successful, our business could be negatively impacted. Additionally, in some instances, our agreements with third parties may include certain indemnification provisions which, if triggered, may negatively impact our business.

•Third parties we rely on for the execution of nonclinical studies and clinical trials may fail to carry out their contractual duties.

•We may be unable to use third-party manufacturing sites, our third-party manufacturers may encounter difficulties in production, or we may need to switch or create third-party manufacturer redundancies.

Other Risk Factors - Risks Related to Employee Matters, Managing Growth, Other Risks Related to Our Business, and Owning Our Ordinary Shares

•Our business is dependent on key personnel and we will be harmed if we cannot recruit and retain highly qualified personnel to successfully implement our business strategy.

•In order to successfully implement our plans and strategies, we will need to grow the size of our organization and we may experience difficulties in managing this growth.

•Our estimates of market opportunity and forecasts of market growth may prove to be inaccurate, and even if the markets in which we compete achieve the forecasted growth, our business may not grow at similar rates, or at all.

•Significant disruptions of information technology systems or breaches of data security could adversely affect our business.

•Changes in and failures to comply with United States and foreign privacy and data protection laws, regulations, and standards may adversely affect our business, operations, and consolidated financial performance.

•We may become exposed to costly and damaging liability claims and our insurance may not cover all damages from such claims.

•Our business could be adversely affected by macroeconomic conditions, including tariffs.

•We do not anticipate paying any dividends in the foreseeable future.

•Future sales of shares by existing shareholders, including any shares issuable upon exercise of any pre-funded warrants, could cause our share price to decline.

•Future sales and issuances of equity and debt could result in additional dilution to our shareholders and could cause our share price to decline.

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Part I. Financial Information

Item 1. Financial Statements

CRESCENT BIOPHARMA, INC.

CONDENSED CONSOLIDATED BALANCE SHEETS

(UNAUDITED)

(in thousands, except share and per share amounts)


	June 30,		December 31,
	2026		2025
Assets
Current assets:
Cash and cash equivalents	$	171,593	$	213,192
Accounts receivable, net	—		18,000
Prepaid expenses and other current assets	7,413		5,463
Total current assets	179,006		236,655
Property and equipment, net	876		846
Operating lease right-of-use assets	1,271		1,469
Restricted cash	107		107
Other assets	1,498		1,216
Total assets	$	182,758	$	240,293
Liabilities and Shareholders’ Equity
Current liabilities
Accounts payable	$	2,542	$	9,997
Accrued expenses and other current liabilities	7,407		16,344
Related party accounts payable and other current liabilities	—		140
Deposit liability	5,000		5,000
Deferred revenue	3,117		4,156
Operating lease liability, current	471		435

Total current liabilities	18,537		36,072
Long term liabilities
Operating lease liability, noncurrent	966		1,209
Total liabilities	19,503		37,281
Commitments and contingencies (Note 13)
Shareholders’ equity:
Non-voting convertible preferred shares, $0.001 par value; 5,000,000 shares authorized as of June 30, 2026 and December 31, 2025; 2,890 Series A designated shares issued and outstanding as of June 30, 2026 and December 31, 2025	4,000		4,000
Ordinary shares, $0.001 par value; 175,000,000 shares authorized as of June 30, 2026 and December 31, 2025, 27,756,044 and 27,556,767 shares issued and outstanding as of June 30, 2026 and December 31, 2025, respectively	28		28
Additional paid-in capital	379,156		370,793
Accumulated deficit	(219,929)		(171,809)
Total shareholders' equity	163,255		203,012
Total liabilities and shareholders’ equity	$	182,758	$	240,293

The accompanying notes are an integral part of these condensed consolidated financial statements.

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CRESCENT BIOPHARMA, INC.

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS

(UNAUDITED)

(in thousands, except share and per share amounts)


	Three Months Ended June 30, 2026		Six Months Ended June 30, 2026		Three Months Ended June 30, 2025		Six Months Ended June 30, 2025
License agreement revenue	$	—	$	1,039	$	—	$	—
Operating expenses
Research and development(1)	19,391		37,294		12,081		22,708
General and administrative(2)	8,743		16,608		8,949		12,547
Total operating expenses	28,134		53,902		21,030		35,255
Other income	1,770		1,770		—		—
Loss from operations	(26,364)		(51,093)		(21,030)		(35,255)
Other income (expense):
Interest income	1,527		2,973		313		502
Interest expense(3)	—		—		(1,073)		(2,185)
Total other income (expense)	1,527		2,973		(760)		(1,683)
Net loss and comprehensive loss	$	(24,837)	$	(48,120)	$	(21,790)	$	(36,938)

Net loss per share attributable to ordinary shareholders, basic and diluted	$	(0.74)	$	(1.44)	$	(4.93)	$	(14.11)
Net loss per share attributable to Series A non-voting convertible preferred shareholders, basic and diluted	$	(743.25)	$	(1,442.56)	$	(4,930.97)	$	(14,104.90)

Weighted-average ordinary shares outstanding used in computing net loss per share to ordinary shareholders, basic and diluted	30,532,234		30,465,395		3,856,925		2,331,339
Weighted-average Series A non-voting convertible preferred shares outstanding used in computing net loss per share to Series A non-voting convertible preferred shareholders, basic and diluted	2,890		2,890		565		286

_________________________

(1)Includes related party amount of $0 and $2,923 for the three and six months ended June 30, 2026 and $6,292 and $15,069 for the three and six months ended June 30, 2025, respectively.

(2)Includes related party amount of $0 and $0 for the three and six months ended June 30, 2026 and $164 and $630 for the three and six months ended June 30, 2025, respectively.

(3)Includes related party amount of $0 and $0 for the three and six months ended June 30, 2026 and $420 and $865 for the three and six months ended June 30, 2025, respectively.

The accompanying notes are an integral part of these condensed consolidated financial statements.

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CRESCENT BIOPHARMA, INC.

CONDENSED CONSOLIDATED STATEMENTS OF CONVERTIBLE PREFERRED SHARES AND SHAREHOLDERS' EQUITY (DEFICIT)

(UNAUDITED)

(In thousands, except share amounts)


	Convertible Preferred Stock			Non-Voting Preferred Shares			Ordinary Shares(1)			Additional Paid-in Capital		Accumulated Deficit		Total Shareholders' Equity (Deficit)
	Shares	Amount		Shares	Amount		Shares	Amount
Balances as of December 31, 2024	20,000,000	$	4,000	—	$	—	1,018,604	$	1	$	2,387	$	(17,867)	$	(15,479)
Stock-based compensation expense	—	—		—	—		—	—		466		—		466
Early exercise of stock options	—	—		—