SinoMab BioScience Limited — Report Publication Announcement 2025

Apr 24, 2025

SinoMab BioScience Limited

中國抗體製藥有限公司

(Incorporated in Hong Kong with limited liability)

（於香港註冊成立之有限公司）

(Stock Code 股份代號：3681)

NOTIFICATION LETTER

25 April 2025

Dear Registered Shareholders,

SinoMab BioScience Limited (the "Company")

— Notice of Publication of 2024 Annual Report, Circular, Notice of Annual General Meeting and Proxy Form (the "Current Corporate Communications")

The Current Corporate Communications of the Company have been published in English and Chinese languages and are available on the website of The Stock Exchange of Hong Kong Limited ("HKEX") at www.hkexnews.hk ("HKEx Website") and the Company's website at www.sinomab.com ("Company Website"). If you have any difficulty in receiving or gaining access to the Current Corporate Communications posted on the Company website for any reason, please send your request (specifying your name, address and request) by email at message@sinomab.com or by notice in writing to the Company's share registrar (the "Share Registrar"), Computershare Hong Kong Investor Services Limited, at 17M Floor, Hopewell Centre, 183 Queen's Road East, Wan Chai, Hong Kong. The Company will promptly upon receipt of your request send the Current Corporate Communications to you in printed form free of charge.

Arrangement of Electronic Dissemination of Corporate Communications

Pursuant to Rule 2.07A of the Rules Governing The Listing of Securities on The Stock Exchange of Hong Kong Limited (the "Listing Rules") in respect of the expansion of paperless listing regime and electronic dissemination of corporate communications that came into effect on 31 December 2023, the Company is writing to inform you that the Company has adopted electronic dissemination of corporate communications ("Corporate Communications"), which term under the Listing Rules means any document issued or to be issued by the Company for the information or action of holders of any of its securities, including but not limited to (a) the directors' report, its annual accounts together with a copy of the auditors' report and, where applicable, its summary financial report; (b) the interim report and, where applicable, its summary interim report; (c) a notice of meeting; (d) a listing document; (e) a circular; and (f) a proxy form.

Please note that both the English and Chinese versions of all future Corporate Communications will be available electronically on the Company Website at www.sinomab.com and the HKEx website at www.hkexnews.hk (the "Website Version") in place of printed copies.

Solicitation of Electronic Contact Details

To ensure timely receipt of the latest Corporate Communications and Actionable Corporate Communications, please complete, sign and return the enclosed reply form (the "Reply Form") to the Share Registrar or by email to message@sinomab.com.

If you are a new registered shareholder, the Company would like to seek your consent of receiving the Company's Corporate Communications via electronic means. If the Company does not receive the duly completed and signed Reply Form or any response in writing indicating any objection from you by 23 May 2025, and until you inform the Share Registrar, you are deemed to have consented to receive all future Corporate Communications published on the Company Website and HKEx Website, and a notification of the publication of the Corporate Communications on the Company Website will be sent to you in the future via email or by post (only if the Company does not possess the functional email address of a Shareholder).

If you elect to receive the Website Version of future Corporate Communications, you are requested to provide an email address in the Reply Form for the purposes of receiving (i) email notifications for the publication of the relevant Corporate Communications on the Company Website and the HKEx Website as and when the relevant Corporate Communications are published on the Company Website and HKEx Website and (ii) all future Actionable Corporate Communications (None) in electronic form from the Company. If no email address is provided by you in the Reply Form or if you are otherwise deemed to have consented to receive the Website Version of future Corporate Communications as described above, the Company will send to you by post, (i) a notification letter for the publication of Corporate Communications on the Company Website and HKEx Website and (ii) all future Actionable Corporate Communications in printed form, until such time when you have provided a valid and functional email address to the Company and/or the Share Registrar for receiving the same.

Should you object to receiving the Website Version of future Corporate Communications, the Company will send you Corporate Communications in printed form.

As Actionable Corporate Communications are important corporate communications that seek your instructions on how to exercise your rights or make an election as a shareholder of the Company, it is of paramount importance to ensure that the email address to be provided by you in the Reply Form is valid and functional at all times; otherwise you may not be able to receive the Actionable Corporate Communications on time or at all so as to exercise your rights or make an election as a shareholder of the Company promptly within the timeframe required under the Actionable Corporate Communications. If the Company has attempted to send the Actionable Corporate Communication(s) in electronic form to the email address provided by you in the Reply Form and subsequently received a non-delivery message, the Company will re-send the relevant Actionable Corporate Communication(s) in printed form (accompanied with a request for your functional email address to facilitate electronic dissemination of Actionable Corporate Communications in future) to your address as shown in the Company's register of members.

You are entitled to change the choice of means of receipt of all future Corporate Communications at any time by serving reasonable notice (of not less than 7 days) in writing to the Share Registrar by mail at 17M Floor, Hopewell Centre, 183 Queen's Road East, Wan Chai, Hong Kong or by email to message@sinomab.com. Even if you have elected (or are deemed to have consented) to receive the Website Version of all future Corporate Communications, if for any reason you have difficulty in accessing the Corporate Communications published on the Company Website and/or the HKEx Website, or wish to receive Corporate Communications in printed form, the Company or the Share Registrar will, upon receipt of a written request by mail (at the address above) or by email to message@sinomab.com, promptly send you the Corporate Communications in printed form free of charge.

Please note that English and Chinese versions of all future Corporate Communication(s) will be available (a) in printed form from the Company or the Share Registrar on request; and (b) on the Company Website at www.sinomab.com and on the HKEx Website at www.hkexnews.hk.

Should you have any queries relating to this letter, please contact the Company at (852) 3426 9833 during business hours from 8:30 a.m. to 5:30 p.m. (Hong Kong time), Mondays to Fridays, excluding Hong Kong public holidays, or by sending an email to message@sinomab.com.

Yours faithfully,

By order of the Board

SinoMab BioScience Limited

Dr. Shui On LEUNG

Executive Director, Chairman and Chief Executive Officer

Note: Corporate Communications refer to any documents issued or to be issued by the Company for the information or action of holders of any of its securities, including, but not limited to, (a) the directors' report, its annual accounts together with a copy of the auditors' report and, where applicable, its summary financial report; (b) the interim report and, where applicable, its summary interim report; (c) a notice of meeting; (d) a listing document; (e) a circular; and (f) a proxy form. Pursuant to Rule 1.01 of the Listing Rules, Actionable Corporate Communications" are any corporate communications that seek instructions from issuer's securities holders on how they wish to exercise their rights or make an election as the issuer's securities holder.

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SinoMab BioScience Limited

中國抗體製藥有限公司

(Incorporated in Hong Kong with limited liability)

（於香港註冊成立之有限公司）

(Stock Code 股份代號：3681)

通知信函

各位登記股東：

中國抗體製藥有限公司（「本公司」）
- 2024年年度報告、股東週年大會通函、股東週年大會通告及代表委任表格（「本次公司通訊文件」）之發佈通知

本公司的本次公司通訊文件備有中、英文版本，並已上載於香港聯合交易所有限公司（「香港交易所」）網站（www.hkexnews.hk）（「香港交易所網站」）及本公司網站（www.sinomab.com）（「公司網站」），歡迎瀏覽。閣下若因任何理由以致在收取或接收載於本公司網址上的本次公司通訊文件出現困難，閣下可將要求（註明閣下的姓名、地址及要求）以電郵方式發送到本公司之電郵地址 message@sinomab.com 或以書面方式郵寄致本公司的股份過戶登記處（「股份過戶處」）香港中央證券登記有限公司，地址為香港灣仔皇后大道東183號合和中心17M樓。本公司將於接到閣下通知後，盡快向閣下免費發送有關本次公司通訊文件的印刷本。

以電子方式發布公司通訊之安排

根據於2023年12月31日起生效的香港聯合交易所有限公司證券上市規則（「上市規則」）第2.07A條有關擴大無紙化上市機制及以電子方式發布公司通訊規定，本公司謹此通知閣下其就採用以電子方式發佈公司通訊（「公司通訊」）作出安排。該詞語根據上市規則是指公司發出或將予發出以供其任何證券持有人參照或採取行動的任何文件，其中包括但不限於(a)董事會報告、年度賬目連同核數師報告以及（如適用）財務摘要報告；(b)中期報告及（如適用）其中期摘要報告；(c)會議通告；(d)上市文件；(e)通函；及(f)代表委任表格。

請注意，所有日後公司通訊的英文版和中文版將在公司網站 www.sinomab.com 及香港交易所網站 www.hkexnews.hk（「網上版本」）上提供，以代替印刷本。

徵集電子聯絡資料

為確保及時收到最新的公司通訊及可供採取行動的公司通訊，請填妥、簽署隨附之回條（「回條」）並交回至公司股份過戶處，或以電郵形式發送至 message@sinomab.com。

倘閣下為本公司的新登記股東，本公司欲徵求閣下的同意以電子方式接收本公司的公司通訊。倘若本公司於二零二五年五月二十三日之前尚未收到閣下已填妥並簽署之回條或表示反對之任何書面回覆，閣下將被視為已同意公司可通過在公司網站及香港交易所網站上提供公司通訊的方式向閣下發送或提供所有日後公司通訊，而本公司日後將透過電子郵件或郵寄方式（倘本公司並無擁有股東的有效電郵地址）向閣下發送在公司網站登載的公司通訊之通知。

倘閣下選擇接收日後公司通訊的網上版本，閣下需要在回條中提供電郵地址，以便接收(i)在公司網站及香港交易所網站登載公司通訊時，在公司網站及香港交易所網站登載相關公司通訊的電郵通知，及(ii)公司以電子形式發佈的所有日後可供採取行動的公司通訊（附註）。倘閣下並未在回條提供電郵地址或倘閣下被視為已同意接收上述日後公司通訊的網上版本，公司將以郵寄方式向閣下發送(i)在公司網站及香港交易所網站登載公司通訊的通知函，及(ii)所有日後可供採取行動的公司通訊之印刷本，直至閣下向本公司及／或股份過戶登記處提供有效且可用的電郵地址以接收所有日後可供採取行動的公司通訊。

倘閣下拒絕日後收取公司通訊之網上版本，本公司將向閣下發送公司通訊之印刷本。

由於可供採取行動的公司通訊為涉及要求閣下指示擬如何行使閣下有關本公司股東的權利或作出選擇的重要公司通訊，因此確保閣下在回條中提供的電郵地址持續有效且可用攸關重要；否則，閣下可能無法按時或根本無法接收可供採取行動的公司通訊，以在可供採取行動的公司通訊要求的時間內及時行使閣下有關本公司股東的權利或作出選擇。倘公司擬以電子形式將可供採取行動的公司通訊發送至閣下在回條中提供的電郵地址，但隨後收到未送達信息，本公司將相關可供採取行動的公司通訊之印刷本（同時要求閣下提供有效的電郵地址，以便於日後以電子方式發佈可供採取行動的公司通訊）重新發送至公司股東名冊上所列的閣下之地址。

閣下可隨時以郵寄方式發送合理書面通知（不少於7日）至股份過戶登記處（地址為香港灣仔皇后大道東183號合和中心17M樓）或以電郵方式發送至 message@sinomab.com，以更改選擇所有日後公司通訊之收取方式。即使閣下已選擇（或被視為已同意）收取所有日後公司通訊之網上版本，如因任何原因令閣下於查閱於公司網站及/或香港交易所網站刊發之公司通訊時出現困難，或擬收取公司通訊之印刷本，本公司或股份過戶登記處將於收取郵寄（如上述地址）或電郵至 message@sinomab.com之書面要求後，立即向閣下免費發送公司通訊之印刷本。

請注意，就日後所有公司通訊的英文版本及中文版本而言，閣下可以(a)提出要求向本公司或股份過戶登記處索取印刷本；及(b)在公司網站www.sinomab.com及香港交易所網站www.hkexnews.hk查閱。

如閣下對本函件有任何疑問，請於辦公時間星期一至星期五（香港台眾假期除外）上午八時三十分至下午五時三十分（香港時間）致電公司(852)34269833查詢，或電郵至 message@sinomab.com。

承董事會合

中國抗體製藥有限公司

執行董事、主席兼首席執行官

梁瑞安博士

謹啟

二零二五年四月二十五日

附註：公司通訊乃指本公司發出或將予發出以供其任何證券持有人參照或採取行動的任何文件。其中包括但不限於：(a)董事會報告、年度賬目連同核數師報告的副本以及（如適用）財務摘要報告；(b)中期報告及（如適用）中期摘要報告；(c)會議通告；(d)上市文件；(e)通函；及由代表委任表格。

根據上市規則第1.01條，「可供採取行動的公司通訊」指任何涉及要求發行人的證券持有人指示其擬如何行使其有關證券持有人的權利或作出選擇的公司通訊。

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CCS2472

SBLH

REPLY FORM 回條

To: SinoMab BioScience Limited (the "Company")
(Stock Code: 3681)
c/o Computershare Hong Kong Investor Services Limited
17M Floor, Hopewell Centre
183 Queen's Road East, Wanchai, Hong Kong

致：中國抗體製藥有限公司（「本公司」或「貴公司」）
（股份代號：3681）
經香港中央證券登記有限公司
香港灣仔量版大道東183號
告和中心17M樓

I/We would like to receive the Corporate Communications® of the Company (the "Corporate Communications") in the manner as indicated below:

本人/簽等希望以下列方式收取貴公司之公司通訊*（「公司通訊」）：

(Please mark ONLY ONE (√) of the following boxes)
(請僅在下列其中一個交格內劃上(√)號)

☐ to access all future Corporate Communication(s) to be published on the Company's website and/or the website of The Stock Exchange of Hong Kong Limited (the "Website Version") only instead of receiving printed copies by mail, and receive an email notification of the publication of the Corporate Communication(s) on the Company's website and the website of The Stock Exchange of Hong Kong Limited (the "HKEx Website") at the email address below; OR

僅須雙所有日後將登載於本公司網站及/或香港聯合交易所有限公司網站之公司通訊（「網上版本」），以代替收取郵寄印刷本，並以以下電郵地址收取就有關公司通訊經已於本公司網站及香港聯合交易所有限公司網站(「香港交易所網站」）登載之通知函的電郵通知（或

Email Address

電郵地址

(The Company will send to the email address provided above (if any) the email notification of the availability of the future Corporate Communications on the Company's website and the HKEx Website, if no email address is provided, (i) printed notification letter of the publication of the Corporate Communications on the Company's website and the HKEx Website; and (ii) all future Actionable Corporate Communications® in printed form will be sent by post. Please provide the email address in English Capital Letters and the email address will solely be used for the purposes of receiving (i) email notification of the publication of Corporate Communications on the Company's website and the HKEx Website; and (ii) all future Actionable Corporate Communications® in electronic form from the Company.)

(本公司日後會將公司通訊經已於本公司網站及香港交易所網站登載之電郵通知發送至如上提供之電郵地址(如有)，如未有提供電郵地址，則會向閣下郵寄借公司通訊已在本公司網站及香港交易所網站登載之通知信函；及(iii)所有日後可供採取行動的公司通訊的印刷本，請以英文正體填寫電郵地址，有關電郵地址僅用作收取借公司通訊已於本公司網站及香港交易所網站登載之電郵通知；及(iii)本公司日後以電子形式發佈之所有可供採取行動的公司通訊。)

☐ to receive by mail the printed version of all future Corporate Communication(s).

以郵寄收取所有日後公司通訊之印刷本。

Signature

蓋名

Name

姓名

Contact telephone number

聯絡電話號碼

Date

日期

Notes 附註：

1. If you are a new registered shareholder and the Company does not receive this Reply Form duly completed and signed by you or does not receive a response indicating an objection from you by 23rd May 2025, you will be deemed to have consented to receiving the Website Version of all future Corporate Communication(s) instead of receiving printed copies by mail. We will only send you a printed notification of the publication of the Corporate Communication(s) on the Company's website and the HKEx Website in the future.
   紙閣下為新登記股東且本公司於截至二零二五年五月二十三日尚未收到閣下填妥及簽署的本回條或表示反對的回覆。閣下將被視為已同意收取所有日後公司通訊之網上版本以代替收取郵寄印刷本。而本公司日後將只向閣下寄發有關公司通訊經已於本公司網站及香港交易所網站登載之通知函印刷本。
2. Shareholders are entitled to change the choice of means of receipt of the Corporate Communication(s) at any time by giving reasonable prior notice (of not less than 7 days) in writing to the Company c/o the Company's Share Registrar or sending such notice by email to the Company's email address at message@slnomab.com.
   股東可以獲得透過本公司之股份通戶處給予本公司合理之事先書面通知（出不少於七天），或以電郵發送該通知至本公司電郵地址. message@sinomab.com。要求更改公司通訊之收取方式之選擇。
3. By selection to access the Website Version of all future Corporate Communication(s) instead of receiving printed copies, you have expressly consented to waive the right to receive the Corporate Communication(s) in printed form. 在選擇須雙所有日後公司通訊之網上版本以代替收取印刷本後，閣下已與公司意欲要收取公司通訊印刷本的權利。
4. If your shares are held in joint names, all the joint holders of the shares should sign on this Reply Form in order to be valid. 如屬聯名股東，則本回條須由所有的聯名股東簽署。方為有效。
5. Any Reply Form with no box marked (+), with no signature or otherwise incorrectly completed will be void. 如在本回條未有作出「√」選擇，或未有簽署，或在其他方面填寫不正確，則本回條將會作廢。

6. For the avoidance of doubt, we do not accept any other instructions given on this Reply Form. 為免存疑，任何在本回條上的任何額外指示，本公司將不予處理。

7. Corporate Communication(s) means any document(s) issued or to be issued by the Company for the information or action of holder(s) of any of its securities, including but not limited to (a) the directors' report, its annual accounts together with a copy of the auditors' report and, where applicable, its summary financial report; (b) the interim report and, where applicable, its summary interim report; (c) a notice of meeting; (d) a billing document; (e) a circular; and (f) a proxy form. 公司通訊版本公司須完成將予發出以供其任何證券持有人參照或採取行動之任何文件，其中包括但不限於「(★)董事會報告、年度數目適用與數額報告的副本以及(如適用)財務輔導報告（(★)中額報告及(如適用)中銀輔導報告（(★)會議通告（(★)上市文件（★）通函）及(F)代表委任者稅。

8. Actionable Corporate Communication(s) means any corporate communication from the Company that seeks instructions from its shareholders on how they wish to exercise their rights or make an election as the shareholders of the Company. 可供採取行動的公司通訊版本公司須求其股東指示地使作為本公司股東如何行使其權利或選擇原勝出之任何公司通訊。

PERSONAL INFORMATION COLLECTION STATEMENT 收集個人資料聲明

"Personal Data" in this statement has the same meaning as "personal data" in the Personal Data (Privacy) Ordinance, Cap 490 ("PDPO"), which includes your name, mailing address, contact telephone number, e-mail address and/or your choice.

本聲明所指的「個人資料」具有《個人資料（私隱）條例》（第4條款）、「私隱條例」及關於「個人資料」之相同涵義，當中包括閣下的姓名、郵寄地址、聯絡電話號碼、電郵地址及/或閣下的選擇。

Your Personal Data provided in this form will be used in connection with processing your request for obtaining printed copy of the relevant Corporate Communication(s) and Actionable Corporate Communication(s). Your supply of Personal Data is on a voluntary basis. However, the Company may not be able to process your request unless you provide us with your Personal Data.

閣下於本表格所提供的個人資料將用以處理閣下要求索取相關公司通訊及可供採取行動的公司通訊印刷本之指示。閣下乃僅於自願性閱提供個人資料，恆候閣下並無提供個人資料，本公司可能無法處理閣下的指示。

Your Personal Data may be disclosed or transferred to the Company's Share Registrar for the purpose stated above, or when it is required to do so by law, for example, in response to a court order or a law enforcement agency's request, and will be retained for such period as may be necessary for our verification and record purpose.

本公司可能上述用途將閣下的個人資料統置成轉移給本公司的股份通戶處，或按法例規定（例如應法庭命令或執法機關的要求）作出統置或轉移，並將在適當期間內保留該等個人資料作核實及記錄用途。

You have the right to request access to and/or correction of your Personal Data respectively in accordance with the provisions of the PDPO. Any such request for access to and/or correction of your Personal Data should be in writing by either of the following means:

閣下有權根據私隱條例分別准閱及/或更正閣下的個人資料，任何准閱及/或更正閣下個人資料的要求，均須透過以下其中一項述經以書面方式提出：

By mail to:
Personal Data Privacy Office
e-mail

Computershare Hong Kong Investor Services Limited
17M Floor, Hopewell Centre, 183 Queen's Road East,
Wanchai, Hong Kong

By email to:
Office\Office\@computershare.com.hk

電郵：

香港灣仔
皇后大道東183號合和中心17M樓
香港中央證券登記有限公司
個人資料私隱主任
Privacy\Office\@computershare.com.hk

Mailing Label 簽署標籤

Computershare Hong Kong Investor Services Limited
香港中央證券登記有限公司
Freeport No. 簡便回解號碼：37
Hong Kong 香港

Please cut the mailing label and stick it on an envelope to return this form to us.
No postage is necessary if posted in Hong Kong.

當閣下寄回此段條例、請將簽署標籤緊貼於放於上。
如在本港投寄，閣下無需支付銀寶或貼上銀票。