Shanghai / Hong Kong, China

August 28, 2026

Key Business Highlights for 1H 2026

·   The Company’s two core assets entered pivotal-stage development and the regulatory filing stage. Elfetabart drozuntecan (DB-1311/BNT324, elfe-D), a B7-H3 ADC, initiated its first global randomized Phase 3 clinical trial, while the Biologics License Application (BLA) for trastuzumab pamirtecan (DB-1303/BNT323, T-Pam), a HER2 ADC, for the treatment of adult patients with unresectable or metastatic HER2-positive breast cancer was accepted for review by the Center for Drug Evaluation (CDE) of China’s National Medical Products Administration (NMPA).

·   DB-1311 continued to demonstrate “Pipeline-in-a-Product” potential, while the ADC + IO 2.0 combination strategy achieved initial frontline clinical validation. The Company served written notice on BioNTech to exercise the exclusive cost and profit/loss sharing option for elfe-D in the U.S. market. The parties are advancing both monotherapy and combination development strategies across multiple tumor types, including prostate cancer and lung cancer, spanning more than ten indications in total. More than 1,000 patients have been treated globally, including over 500 patients treated with elfe-D in combination with pumitamig, a PD-L1 x VEGF bispecific antibody. Multiple key data readouts and subsequent registrational studies are being advanced.

·   The Company further deepened its global partnerships, bringing cumulative deal value to more than US$7.0 billion. The Company entered into a global strategic research and development collaboration with Genentech to develop next-generation ADCs based on its proprietary DUPAC platform. Designed to address resistance to the payload classes underlying currently approved ADCs, DUPAC has the potential to continuously generate differentiated next-generation ADC candidates.

·   A strong cash position and diversified capital markets strategy provide long-term support for realizing the global value of the Company’s pipeline. In the first half of 2026, research and development expenses were approximately RMB606.7 million, representing a year-on-year increase of approximately 73.6%, while cash and bank balances were approximately RMB3.01 billion. The Shanghai Stock Exchange accepted the Company’s application for an initial public offering of RMB-denominated ordinary shares, or A shares, and listing on the STAR Market, marking a new chapter in the Company’s dual “H+A” capital markets strategy.

·   The Company’s global clinical network keeps expanding. As of June 30, 2026, the Company’s clinical trials were being conducted in approximately 20 countries, with more than 3,500 patients enrolled. Approximately 50% of these patients were enrolled in the United States, the European Union, Australia and other markets outside China.

Duality Biotherapeutics, Inc. (DualityBio, HKEX: 09606, or the “Company”) today announced its consolidated results for the six months ended June 30, 2026, and provided an update on its key business developments and operations. During the first half of 2026, the Company focused on advancing its core products into pivotal clinical development and toward registration; continuing to advance its ADC plus next-generation immuno-oncology combination strategy with BioNTech; driving platform-enabled innovation across oncology and autoimmune diseases; and further deepening its global collaboration model. At the same time, the Company continued to expand its capital markets presence to enhance its long-term value creation capabilities.

Dr. John ZHU, Founder and CEO of DualityBio, commented: “In the first half of 2026, DualityBio continued to advance its strategic vision of global innovation, global development and global value creation, achieving important progress across innovative research and development, global partnerships and capital markets initiatives. We are pleased to see our two core assets advance into pivotal clinical development and regulatory filing stages, further validating our ability to translate innovative science into global therapeutic value. At the same time, DB-1311/elfe-D continued to demonstrate broad ‘Pipeline-in-a-Product’ potential, while our next-generation ADC technology platforms continued to expand the boundaries of innovation. Together with global partners, we are building an innovation ecosystem for the future. With our expanding global clinical network, strong cash position and emerging dual ‘H+A’ capital markets platform, we are more determined than ever to become a leading global innovative biopharmaceutical company, bring more breakthrough treatment options to patients worldwide, and contribute to the globalization of Chinese biopharmaceutical innovation.”

Advancing Our Core Products Toward Pivotal Stage and Registration

Elfetabart drozuntecan (DB-1311/BNT324, elfe-D)

Elfe-D has now been studied in more than 1,000 patients across more than ten tumor types, including over 500 treated in combination with pumitamig (PD-L1xVEGF bsAb). In the first half of 2026, the program advanced across pivotal execution, regulatory recognition and indication expansion, as we progress from monotherapy into next-generation IO combinations.

In February 2026, updated data from the ongoing global Phase 1/2 clinical trial (NCT05914116) were presented at the ASCO GU Cancers Symposium. As of the December 29, 2025 data cutoff, elfe-D demonstrated a median rPFS of 11.3 months and a mOS of 22.5 months in patients with heavily pretreated mCRPC (including patients with prior Lu-177 treatment; n=129 evaluable), with safety findings consistent with prior reports and no new safety signals reported.

Building on this encouraging clinical activity, in May 2026, the first patient was dosed in our first global, randomized Phase 3 trial for this program (NCT07365995) versus docetaxel in taxane-naive mCRPC. The trial plans to enroll approximately 736 patients.

In July 2026, the CDE of the NMPA granted elfe-D Breakthrough Therapy Designation for the treatment of patients with mCRPC that has progressed following an androgen receptor pathway inhibitor and taxane-based chemotherapy.

The program continues to advance beyond prostate cancer. In April 2026, updated data from the same trial (NCT05914116) were presented at the SGO Annual Meeting, showing encouraging clinical activity in previously treated cervical cancer, particularly in the second-line setting, as well as in PROC. The safety profile in gynecologic malignancies was consistent with previous reports, and no new safety signals were observed. Data updates from this trial in patients with PROC are expected to be presented at the 2026 ESMO Congress.

Elfe-D was granted Breakthrough Therapy Designation by the Center for Drug Evaluation of China’s National Medical Products Administration for the treatment of metastatic castration-resistant prostate cancer that has progressed following prior treatment with an androgen receptor pathway inhibitor and taxane-based chemotherapy.

Trastuzumab pamirtecan (DB-1303/BNT323, T-Pam)

T-Pam continues to advance rapidly toward registration across breast cancer (BC) and endometrial cancer (EC). In April 2026, the CDE of the NMPA accepted for review the first BLA for T-Pam for the treatment of adult patients with unresectable or metastatic HER2-positive BC. During the same period, data from the potentially registrational EC cohort of the global Phase 1/2a clinical trial (NCT05150691) were presented at the SGO Annual Meeting. T-Pam demonstrated clinical efficacy across all HER2 expression levels (IHC 3+, 2+ and 1+) and regardless of prior IO treatment. The safety profile in patients with pretreated advanced or metastatic EC was manageable and generally consistent with that of HER2-targeted biologics. Supported by the clinical evidence, the Company and BioNTech plan to file a BLA* in 2026 to advance the asset’s global regulatory pathway, in line with the parties’ strategy to maximize the asset’s value.

In addition, the global Phase 3 DYNASTY-Breast02 clinical trial (NCT06018337) in patients with HR-positive, HER2-low metastatic BC completed enrollment in February 2026.

Note: Subject to the totality of the data from the two ongoing trials in endometrial and breast cancer, and subject to regulatory feedback.

Executing Our ADC + Next-Generation IO Combination Strategy with BioNTech

Together with BioNTech, we are advancing an ADC + next-generation IO combination strategy designed to move our ADCs into earlier lines of treatment. Four combination trials across our three collaborative assets are underway.

•            NCT06892548: A global Phase 1/2 clinical trial evaluating elfe-D in combination with pumitamig in advanced lung cancers. Data from this trial are expected to be presented at 2026 WCLC.

•            NCT06953089: A global Phase 2 clinical trial evaluating elfe-D in combination with pumitamig in advanced solid tumors. Data from this trial are expected to be presented at 2026 ESMO Congress.

•            NCT06827236: A global Phase 1/2 clinical trial evaluating T-pam in combination with pumitamig in HR+ or HR-, HER2-low, ultralow, or null advanced metastatic BC or TNBC. Preliminary data from this trial are expected to be presented at the 2026 ESMO Congress.

•            NCT05438329: A global Phase 1/2a trial evaluating sacituzumab drozuntecan in combination with pumitamig in advanced solid tumors. In May 2026, at the 2026 ESMO BC Congress, data from the Phase 2 expansion cohort of the trial evaluating sacituzumab drozuntecan in combination with pumitamig as first-line treatment for unresectable, advanced or metastatic TNBC were presented. As of the February 28, 2026 data cutoff, the combination achieved a uORR of 83.3%, a cORR of 76.7% and a DCR of 96.7% (n=30). Responses were durable, with a six-month duration-of-response rate of 95.2%, and the safety profile was manageable.

Sustaining Our Platform-Driven Innovation Across Oncology and Autoimmune Disease

Our four proprietary platforms (DITAC, DIBAC, DIMAC and DUPAC) continued to replenish and diversify our pipeline across oncology and autoimmune disease:

DITAC：

DB-1317 (ADAM9 ADC)

In January 2026, DB-1317 received IND clearance from the CDE of the NMPA. In April 2026, the trial design was presented at the 2026 AACR Annual Meeting. The trial is currently enrolling patients. In August 2026, DB-1317 received Fast Track Designation from the U.S. Food and Drug Administration for the treatment of advanced/unresectable or metastatic pancreatic ductal adenocarcinoma (PDAC).

DB-1324 (CDH17 ADC)

A global Phase 1/2 trial (NCT07263594) in advanced/metastatic gastrointestinal tumors is enrolling. In April 2026, the trial design of this study was presented at the 2026 AACR Annual Meeting.

DB-1329 (CDCP1 ADC):

In April 2026, preclinical data for DB-1329 were presented at the 2026 AACR Annual Meeting, demonstrating strong antitumor activity across multiple animal models. Notably, its discovery was supported by DBNexus™, the Company’s proprietary AI multi-omics platform.

DIBAC：

DB-1418/AVZO-1418 (EGFR×HER3 BsADC)

In May 2026, the first patient in China was dosed in a global Phase 1/2 trial (AVENTINE-1, NCT07038343) in patients with advanced solid tumors. In June 2026, preliminary Phase 1 data from this trial were publicly disclosed. As of the May 13, 2026 data cutoff, responses were observed in five of 18 efficacy-evaluable patients across multiple tumor types and dose cohorts, and nine of 18 remained on treatment. DB-1418/AVZO-1418 was generally well tolerated at doses up to 4.5 mg/kg Q2W, where the majority of TEAEs were Grade 1 or 2 (n=20). Avenzo plans to present preliminary updated Phase 1 data from this trial in the second half of 2026.

DIMAC：

DIMAC is a globally leading autoimmune disease technology platform with the potential to enable potential “steroid-free” treatment and expand to additional targets, further unlocking the value of next-generation ADC innovation.

DB-2304 (BDCA2 ADC)

The Phase 2a portion in patients with systemic lupus erythematosus/cutaneous lupus erythematosus (SLE/CLE) of a global Phase 1/2a clinical trial (NCT06625671) is actively enrolling patients.

DUPAC：

Comprising novel-mechanism payload technologies with published patents, including DUP5, DUP9 and DUP10, DUPAC is designed to address resistance to the payload classes underlying currently approved ADCs.

DB-1326 (dual-payload, TA-MUC1 ADC)

In April 2026, preclinical data for DB-1326 were presented at the 2026 AACR Annual Meeting, demonstrating superior antitumor efficacy over mono-payload ADCs in preclinical tumor models, along with encouraging pharmacokinetic and safety profiles in monkeys.

AI-Driven R&D Innovation

We are embedding AI across both drug discovery and translational development, through in-house capabilities such as DBNexus™ as well as external collaborations. In May 2026, we partnered with Tsinghua University Shenzhen International Graduate School (“Tsinghua SIGS”) to co-develop Patho3DMatrix-Vision-DualityBio, a dedicated pathology foundation model trained on our own clinical trial data. The model strengthens our in-house capabilities in biomarker discovery, patient stratification and treatment-response prediction across our programs.

Expanding Our Global Partnership Franchise in Value and Reach

Building on seven global collaborations with an aggregate deal value of more than US$7.0 billion across partners including BioNTech, BeOne, GSK, Avenzo, Adcendo and Genentech, the Company further extended its global reach.

In May 2026, we served written notice on BioNTech to exercise the exclusive cost and profit/loss sharing option for elfe-D in the U.S. market.

In August 2026, we entered into a collaboration and license with Genentech, a member of the Roche Group, to develop next-generation ADCs built on our DUPAC platform. Under the agreement, we will receive an upfront payment of US$45 million and will be eligible to receive potential development, regulatory and commercial milestone payments of up to an aggregate of more than US$1 billion across all collaboration programs. In addition, we will be entitled to receive tiered royalty payments on annual net sales of approved products arising from the collaboration.

Deepening the Company’s Capital Markets Presence to Enhance Long-Term Value Creation

In June 2026, the Shanghai Stock Exchange formally accepted the Company’s application for an initial public offering of RMB-denominated ordinary shares (A shares) and listing on the STAR Market, marking the official commencement of a new chapter in the Company’s dual “H+A” capital markets strategy.

During the Reporting Period, we repurchased a total of 400,100 Shares on the Stock Exchange for a total consideration of approximately HK$78.11 million. This proactive repurchase initiative reflects our firm confidence in long-term business growth prospects and the realization of intrinsic value. Furthermore, at the annual general meeting held on June 26, 2026, a resolution was passed to grant a general mandate to the Directors to repurchase Shares of the Company not exceeding 10% of the total number of Shares of the Company in issue (excluding treasury shares) as at the date of passing of this resolution.

Financial Overview

In the first half of 2026, the Company continued to increase its investment in the global clinical development of core products, the expansion of its innovative pipeline and the development of advanced technology platforms. Research and development expenses amounted to approximately RMB606.7 million, representing a year-on-year increase of 73.60%. The increased R&D investment primarily supported the global clinical development of core products, the advancement of the innovative pipeline, and continued innovation across next-generation ADC technology platforms and AI-enabled research and development. These investments further strengthened the Company’s global R&D and clinical execution capabilities and laid a solid foundation for building a globally competitive and differentiated product portfolio, improving R&D efficiency and achieving sustainable long-term growth.

As of June 30, 2026, the Company had cash and bank balances of approximately RMB3.01³ billion, maintaining a strong financial position. The Company’s solid cash position provides substantial financial support for the continued global clinical development of its core products, the expansion of its innovative pipeline, the deepening of global strategic collaborations and the execution of its long-term development plans.

The Company remains at the innovative drug research and clinical development stage. Supported by its expanding global collaboration network and multiple out-licensing transactions completed to date, the Company recorded revenue of approximately RMB219.3 million and a loss of approximately RMB918 million during the reporting period. After adding back the one-time revenue deduction of approximately RMB290.7 million arising from the exercise of the U.S. cost and profit/loss sharing option for elfe-D, adjusted revenue was approximately RMB510.0¹ million and adjusted loss for the period was approximately RMB626.9² million.

Note:

1.Calculated by adding back the one-off impact of revenue deduction arising from the exercise of the exclusive cost and profit/loss sharing option for DB-1311/BNT324 in the U.S. market. For the six months ended June 30, 2026 and June 30, 2025, the portion of historical development costs attributable to the U.S. market was recognized as deduction from revenue in the interim condensed consolidated statement of comprehensive loss, amounting to RMB290.7 million and nil, respectively.

2. Calculated by deducting fair value change of financial liabilities at fair value through profit or loss from loss for the period, and adding back deduction of revenue due to exercise of the exclusive cost and profit/loss sharing option for DB-1311/BNT324 for the U.S. market. The revenue deduction arising from the exercise of the exclusive cost and profit/loss sharing option for DB-1311/BNT324 in the U.S. market reflects the one-off impact of the option exercise. For the six months ended June 30, 2026 and June 30, 2025, the portion of historical development costs attributable to the U.S. market was recognized as deduction from revenue in the interim condensed consolidated statement of comprehensive loss, amounting to RMB290.7 million and nil, respectively. The fair value change of financial liabilities at fair value through profit or loss primarily arose from our preferred shares issued in connection with previous equity financings prior to the Global Offering. Such fair value changes were recognized up until April 15, 2025, the date of completion of our Global Offering. From this date onward, these preferred shares ceased to exist, and there will be no further profit or loss impact of this nature in subsequent financial periods. For the six months ended June 30, 2026 and June 30, 2025, the fair value change of financial liabilities at fair value through profit or loss amounted to nil and a loss of RMB2,219.8 million, respectively.Please refer to the section headed “Financial Review — Non-HKFRS Measure” in this announcement for further details. Comprises cash and cash equivalents, restricted cash and term deposits with initial term over three months

3. Comprises cash and cash equivalents, restricted cash and term deposits with initial term over three months

Forward-Looking Statements

This communication contains statements that may be considered “forward-looking statements” under applicable securities laws. Such statements are generally identifiable by the use of words such as “will,” “expect,” “anticipate,” “aim,” “intend,” “plan,” “believe,” “may” and similar expressions. All statements other than statements of historical fact, including statements regarding the beliefs, plans, objectives and expectations of Duality Biotherapeutics, Inc. (the “Company”) concerning its business, research and development programs and product candidates, are forward-looking statements. Forward-looking statements involve inherent risks and uncertainties. A number of factors could cause actual results to differ materially from those contained in any forward-looking statement, including, but not limited to, progress and risks relating to the Company’s research and development, clinical trials, regulatory approvals and commercialization, as well as changes in macroeconomic and industry conditions. The information contained herein is current as of June 30, 2026. Except as required by law or the Listing Rules, the Company undertakes no obligation to publicly update or revise any forward-looking statement.

About DualityBio

DualityBio is a clinical-stage innovative biopharmaceutical company focused on developing next-generation ADCs for patients with cancer and autoimmune diseases. The Company has successfully established multiple next-generation ADC technology platforms with global intellectual property rights. Based on deep research into disease biology, DualityBio has built a broad clinical-stage ADC pipeline and is conducting global multicenter clinical trials across approximately 20 countries, with more than 3,500 patients enrolled. The Company has also entered into multiple global licensing collaborations with leading pharmaceutical companies and innovative biopharmaceutical companies. As a global ADC innovation engine, DualityBio continues to develop next-generation ADCs, including bispecific ADCs, novel-mechanism payload ADCs and autoimmune disease ADCs.

For more information, please visit: www.dualitybiologics.com

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Investor Contact: IR@dualitybiologics.com