Zenas BioPharma (NASDAQ: ZBIO) readies convertible notes; BLA planned after Phase 3 win
Zenas BioPharma is pursuing a securitized capital raise via an offering of convertible senior notes due 2032 and a concurrent equity offering. The company reported positive Phase 3 obexelimab results in IgG4-RD (56% reduction in risk of flare; Hazard Ratio 0.44, p=0.0005) and plans to submit a BLA in Q2 2026.
Earlier Phase 2 MoonStone RMS data showed a sustained reduction in new GdE T1 lesions through week 24. The company is advancing orelabrutinib into global Phase 3 programs (PriMroSe and Monarch) and expects to initiate additional IND-directed Phase 1 studies for ZB021 and ZB022 in 2026. Separately, Zenas entered a Loan Agreement providing for up to $250.0 million in term loans with an initial Tranche A of $75.0 million. The prospectus supplement describes conversion, redemption and repurchase features, ranking and material risks; offering size and many pricing fields are left blank in the provided excerpt.
Positive
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Insights
Positive clinical readouts and a structured credit facility change financing flexibility but raise leverage and execution risk.
The INDIGO Phase 3 topline showing a 56% reduction in IgG4-RD flare (HR 0.44, p=0.0005) supports the company’s plan to file a BLA in Q2 2026, which is a clear regulatory milestone tied to near-term value realization. Simultaneously, the prospectus describes an offering of convertible senior notes due 2032 and a concurrent equity offering to fund a potential U.S. commercial launch and pipeline programs.
However, the Loan Agreement (up to $250.0 million with an initial $75.0 million tranche) increases secured indebtedness and creates structural subordination for the notes. The interplay of debt service, conditional conversion mechanics and optional redemptions means financing execution and timing of the BLA/launch will materially determine debt servicing capacity and dilution outcomes.
Robust Phase 3 IgG4-RD topline and durable Phase 2 RMS signals strengthen the clinical thesis for obexelimab.
The INDIGO Phase 3 result (56% risk reduction; HR 0.44, p=0.0005) and a tolerability profile consistent with earlier trials provide a data-driven basis for the planned BLA submission in Q2 2026. MoonStone Phase 2 RMS results show a 95% relative reduction in new GdE T1 lesions over weeks 8–12, with maintenance to week 24, supporting target engagement in CNS inflammatory disease.
Planned and ongoing registrational efforts for orelabrutinib (PriMroSe and Monarch Phase 3s) and IND-stage programs (ZB021, ZB022) expand the pipeline, but commercialization and regulatory success remain contingent on full data readouts, regulatory review outcomes and the company’s ability to fund launch and pivotal programs.
(To Prospectus dated October 8, 2025)
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PER NOTE
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TOTAL
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Public offering price(1)
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Underwriting discounts and commissions(2)
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Proceeds to Zenas BioPharma, Inc. (before expenses)
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| | TABLE OF CONTENTS | | | |||||
| | PROSPECTUS SUPPLEMENT | | | |
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Page
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ABOUT THIS PROSPECTUS SUPPLEMENT
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| | | | S-ii | | |
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CAUTIONARY NOTE CONCERNING FORWARD-LOOKING STATEMENTS
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| | | | S-iv | | |
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PROSPECTUS SUPPLEMENT SUMMARY
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| | | | S-1 | | |
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THE OFFERING
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| | | | S-5 | | |
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RISK FACTORS
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| | | | S-9 | | |
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USE OF PROCEEDS
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| | | | S-18 | | |
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CAPITALIZATION
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| | | | S-19 | | |
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DESCRIPTION OF NOTES
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| | | | S-21 | | |
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DESCRIPTION OF THE CONCURRENT EQUITY OFFERING
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| | | | S-57 | | |
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MATERIAL U.S. FEDERAL INCOME TAX CONSIDERATIONS
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| | | | S-58 | | |
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UNDERWRITING
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| | | | S-66 | | |
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LEGAL MATTERS
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| | | | S-76 | | |
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EXPERTS
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| | | | S-76 | | |
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WHERE YOU CAN FIND MORE INFORMATION
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| | | | S-76 | | |
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INCORPORATION OF CERTAIN INFORMATION BY REFERENCE
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| | | | S-77 | | |
| | PROSPECTUS | | | | | | | |
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ABOUT THIS PROSPECTUS
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| | | | 1 | | |
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ABOUT THE COMPANY
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| | | | 3 | | |
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RISK FACTORS
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| | | | 5 | | |
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FORWARD-LOOKING STATEMENTS
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| | | | 6 | | |
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USE OF PROCEEDS
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| | | | 8 | | |
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PLAN OF DISTRIBUTION
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| | | | 9 | | |
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DESCRIPTION OF COMMON STOCK
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| | | | 11 | | |
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DESCRIPTION OF PREFERRED STOCK
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| | | | 12 | | |
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DESCRIPTION OF WARRANTS
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| | | | 13 | | |
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DESCRIPTION OF DEBT SECURITIES
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| | | | 14 | | |
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WHERE YOU CAN FIND MORE INFORMATION
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| | | | 22 | | |
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INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE
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| | | | 23 | | |
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LEGAL MATTERS
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| | | | 24 | | |
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EXPERTS
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| | | | 24 | | |
change
agent
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As of December 31, 2025
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(in thousands, except share and per share data)
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Actual
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As adjusted
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Cash, cash equivalents and investments
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| | | $ | 360,464 | | | | | $ | | | |
| Long-term debt: | | | | | | | | | | | | | |
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Royalty obligation
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| | | | 78,636 | | | | | | 78,636 | | |
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% Convertible Senior Notes due 2032 offered hereby
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| | | | — | | | |
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| |||
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Loan Agreement
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| | | | — | | | | | | 75,000 | | |
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Total long-term debt(1)
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| | | $ | 78,636 | | | | | $ | | | |
| Stockholders’ equity: | | | | | | | | | | | | | |
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Preferred stock, $0.0001 par value per share; 25,000,000 shares authorized; no shares issued or outstanding as of December 31, 2025
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| | | $ | — | | | | | $ | — | | |
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Common stock, $0.0001 par value per share; 175,000,000 shares authorized; 54,485,518 shares issued and outstanding as of December 31, 2025(2)
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| | | | 5 | | | |
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| |||
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Additional paid-in capital
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| | | | 1,007,331 | | | | | | 1,007,331 | | |
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Accumulated other comprehensive (loss) income
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| | | | (64) | | | | | | (64) | | |
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Accumulated deficit
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| | | | (765,128) | | | | | | (765,128) | | |
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Total stockholders’ equity
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| | | $ | 242,144 | | | | | $ | | | |
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Total capitalization
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| | | $ | 320,780 | | | | | $ | | | |
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CR0
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| | = | | | the conversion rate in effect immediately before the open of business on the ex-dividend date for such dividend or distribution, or immediately before the open of business on the “effective date” (as defined below under the caption “— Definitions”) of such stock split or stock combination, as applicable; | |
| |
CR1
|
| | = | | | the conversion rate in effect immediately after the open of business on such ex-dividend date or effective date, as applicable; | |
| |
OS0
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| | = | | | the number of shares of our common stock outstanding immediately before the open of business on such ex-dividend date or effective date, as applicable, without giving effect to such dividend, distribution, stock split or stock combination; and | |
| |
OS1
|
| | = | | | the number of shares of our common stock outstanding immediately after giving effect to such dividend, distribution, stock split or stock combination. | |
| |
CR0
|
| | = | | | the conversion rate in effect immediately before the open of business on the ex-dividend date for such distribution; | |
| |
CR1
|
| | = | | | the conversion rate in effect immediately after the open of business on such ex-dividend date; | |
| |
OS
|
| | = | | | the number of shares of our common stock outstanding immediately before the open of business on such ex-dividend date; | |
| |
X
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| | = | | | the total number of shares of our common stock issuable pursuant to such rights, options or warrants; and | |
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Y
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| | = | | | a number of shares of our common stock obtained by dividing (x) the aggregate price payable to exercise such rights, options or warrants by (y) the average of the last reported sale prices per share of our common stock for the 10 consecutive trading days ending on, and including, the trading day immediately before the date such distribution is announced. | |
| |
CR0
|
| | = | | | the conversion rate in effect immediately before the open of business on the ex-dividend date for such distribution; | |
| |
CR1
|
| | = | | | the conversion rate in effect immediately after the open of business on such ex-dividend date; | |
| |
SP
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| | = | | | the average of the last reported sale prices per share of our common stock for the 10 consecutive trading days ending on, and including, the trading day immediately before such ex-dividend date; and | |
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FMV
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| | = | | | the fair market value (as determined by us in good faith and in a commercially reasonable manner), as of such ex-dividend date, of the shares of capital stock, evidences of indebtedness, assets, property, rights, options or warrants distributed per share of our common stock pursuant to such distribution. | |
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CR0
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| | = | | | the conversion rate in effect immediately before the close of business on the last trading day of the “spin-off valuation period” (as defined below) for such spin-off; | |
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CR1
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| | = | | | the conversion rate in effect immediately after the close of business on the last trading day of the spin-off valuation period; | |
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FMV
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| | = | | | the product of (x) the average of the last reported sale prices per share or unit of the capital stock or equity interests distributed in such spin-off over the 10 consecutive trading day period (the “spin-off valuation period”) beginning on, and including, the ex-dividend date for such spin-off (such average to be determined as if references to our common stock in the definitions of “last reported sale price,” “trading day” and “market disruption event” were instead references to such capital stock or equity interests); and (y) the number of shares or units of such capital stock or equity interests distributed per share of our common stock in such spin-off; and | |
| |
SP
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| | = | | | the average of the last reported sale prices per share of our common stock for each trading day in the spin-off valuation period. | |
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CR0
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| | = | | | the conversion rate in effect immediately before the open of business on the ex-dividend date for such dividend or distribution; | |
| |
CR1
|
| | = | | | the conversion rate in effect immediately after the open of business on such ex-dividend date; | |
| |
SP
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| | = | | | the last reported sale price per share of our common stock on the trading day immediately before such ex-dividend date; and | |
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D
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| | = | | | the cash amount distributed per share of our common stock in such dividend or distribution. | |
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CR0
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| | = | | | the conversion rate in effect immediately before the close of business on the last trading day of the “tender/exchange offer valuation period” (as defined below) for such tender or exchange offer; | |
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CR1
|
| | = | | | the conversion rate in effect immediately after the close of business on the last trading day of the tender/exchange offer valuation period; | |
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AC
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| | = | | | the aggregate value (determined as of the time (the “expiration time”) such tender or exchange offer expires by us in good faith and in a commercially reasonable manner) of all cash and other consideration paid or payable for shares of our common stock purchased or exchanged in such tender or exchange offer; | |
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OS0
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| | = | | | the number of shares of our common stock outstanding immediately before the expiration time (including all shares of our common stock accepted for purchase or exchange in such tender or exchange offer); | |
| |
OS1
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| | = | | | the number of shares of our common stock outstanding immediately after the expiration time (excluding all shares of our common stock accepted for purchase or exchange in such tender or exchange offer); and | |
| |
SP
|
| | = | | | the average of the last reported sale prices per share of our common stock over the 10 consecutive trading day period (the “tender/exchange offer valuation period”) beginning on, and including, the trading day immediately after the expiration date; | |
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Make-Whole Fundamental
Change Effective Date |
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Stock Price
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$
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$
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$
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$
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$
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$
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, 2026
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April 1, 2027
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April 1, 2028
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April 1, 2029
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April 1, 2030
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April 1, 2031
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April 1, 2032
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Underwriter
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Principal Amount
of Notes |
| |||
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Jefferies LLC
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| | | $ | | | |
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Evercore Group L.L.C.
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Citigroup Global Markets Inc.
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Guggenheim Securities, LLC
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Wedbush Securities Inc.
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Total
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| | | $ | | | |
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Per Note
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Total
|
| ||||||
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Public offering price(1)
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| | | | % | | | | | $ | | | |
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Underwriting discounts and commissions paid by us
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| | | | % | | | | | $ | | | |
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Proceeds to us, before expenses
|
| | | | % | | | | | $ | | | |
Zenas BioPharma, Inc.
852 Winter Street, Suite 250
Waltham, Massachusetts 02451
(857) 271-2954
email address: IR@zenasbio.com
Preferred Stock
Warrants
Debt Securities
| | | |
Page
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| |||
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ABOUT THIS PROSPECTUS
|
| | | | 1 | | |
|
ABOUT THE COMPANY
|
| | | | 3 | | |
|
RISK FACTORS
|
| | | | 5 | | |
|
FORWARD-LOOKING STATEMENTS
|
| | | | 6 | | |
|
USE OF PROCEEDS
|
| | | | 8 | | |
|
PLAN OF DISTRIBUTION
|
| | | | 9 | | |
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DESCRIPTION OF COMMON STOCK
|
| | | | 11 | | |
|
DESCRIPTION OF PREFERRED STOCK
|
| | | | 12 | | |
|
DESCRIPTION OF WARRANTS
|
| | | | 13 | | |
|
DESCRIPTION OF DEBT SECURITIES
|
| | | | 14 | | |
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WHERE YOU CAN FIND MORE INFORMATION
|
| | | | 22 | | |
|
INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE
|
| | | | 23 | | |
|
LEGAL MATTERS
|
| | | | 24 | | |
|
EXPERTS
|
| | | | 24 | | |
Zenas BioPharma, Inc.
852 Winter Street, Suite 250
Waltham, Massachusetts 02451
(857) 271-2954
email address: IR@zenasbio.com
| | Jefferies | | |
Evercore ISI
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| | Citigroup | | |
Guggenheim Securities
|
|