Genscript Biotech : VOLUNTARY ANNOUNCEMENT - RESEARCH AND DEVELOPMENT UPDATE

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Genscript Biotech Corporation

金斯瑞生 物科 技 股份 有限 公 司 *

(Incorporated in the Cayman Islands with limited liability)

(Stock code: 1548)

VOLUNTARY ANNOUNCEMENT

RESEARCH AND DEVELOPMENT UPDATE

Reference is made to the voluntary announcements of Genscript Biotech Corporation (the "Company" , together with its subsidiaries, the "Group" ) dated 7 November 2019. The board (the "Board" ) of directors (the "Directors" ) of the Company is pleased to announce that the initial data from Phase 1b/2 CARTITUDE-1 study evaluating the efficacy and safety of JNJ-68284528(JNJ-4528) will be reported during an oral presentation at the 2019 American Society of Hematology ( "ASH" ) annual meeting held in Orlando, Florida, the United States on December 9, 2019 and was highlighted in the official ASH press program (Abstract #577).

JNJ-4528 is an investigational B cell maturation antigen (BCMA)-directed chimeric antigen receptor T cell (CAR-T) therapy being evaluated in the treatment of patients with relapsed or refractory multiple myeloma. JNJ-4528 is a structurally differentiated CAR-T cell therapy containing a 4-1BBco-stimulatory domain and 2 BCMA-targetingsingle-domain antibodies designed to confer avidity. The study enrolled patients who have received at least three prior lines of therapy or are double refractory to a proteasome inhibitor (PI) and an immunomodulatory drug (IMiD®); have received a PI, IMiD and an anti-CD38 antibody; and who documented disease progression within 12 months of starting the most recent therapy.

With a data cut-off 6 November 2019 (N=29), the median age of the patients was 60 years (range, 50 -75 years), the median number of prior therapies was five (range, 3-18), and the median administered dose of JNJ-4528 was 0.73x106 CAR+ viable T cells/kg. All patients were triple-exposed, 25 patients (86%) were triple-refractory to a proteasome inhibitor (PI), immunomodulatory drug (IMiD) and anti-CD38. Twenty one patients (72%) were penta-exposed and nine patients (31%) were penta-refractory to ≥2 PIs, ≥2 IMiDs, and anti-CD38.

According to study findings, there was a 100% overall response rate (ORR) (95 percent confidence interval CI, 76-95). Complete response (CR) or better ≥CR was achieved by 69% of patients (95 percent CI, 60-85); very good partial response (VGPR) or better ≥ VGPR was achieved by 86% of patients; and partial response was achieved by 14% of patients. Moreover, 66% of patients had a stringent complete response, meaning that sensitive laboratory and microscopic tests found no evidence for myeloma proteins or cells in blood, urine and bone marrow.

Notably, 100% of patients with ≥CR were minimal residual disease (MRD)-negative at 10-5 sensitivity threshold. With a median follow-up of 6 months, 27 of 29 patients remained progression-free.

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The most common adverse events (AEs) were cytokine release syndrome (CRS) (93%), neutropenia (93%), thrombocytopenia (86%), and anemia (86%). CRS was reported in 27 patients (93%) and was mostly grade 1 - 2. The majority of pts (80%) had grade 1-2 CRS, with 1 grade 3 event and 1 grade 5 event at day 99 from sequalae of grade 4 CRS (dose-limiting toxicity). In patients with CRS, median time of onset was 7 days, with >90% between days 5 - 9. Neurotoxicity (International Colloquium on Advances in Nursing Science, "ICANS" ) was infrequently observed in the context of CRS and generally low-grade (1 patient with grade 3).

Additionally, data highlighting post-infusion CAR+ T cell expansion in the bone marrow and blood of patients enrolled in the CARTITUDE-1 study will be reported (Abstract #928) during an oral presentation at the ASH meeting. While both CD4+ and CD8+ CAR+ T cells expanded in vivo, a preferential expansion of memory CD8+ CAR+ T cells was observed at peak expansion. These and other correlative studies are being conducted to better understand the immune mechanisms associated with response to JNJ-4528, and suggest that the high anti-myeloma activity of JNJ-4528 seen at a relatively low T cell dose is potentially related to its preferential and consistent in vivo expansion of CD8+ CAR+ T cells.

As the results for the CARTITUDE-1 study in the United States emerge, the Company observes that the initial safety and efficacy data are consistent with the LEGEND-2 study in China. In collaboration with Janssen, Legend Biotech is dedicated to advancing the clinical development program of LCAR-B38M/JNJ-4528 for patients with RRMM.

For details in relation to LEGEND-2 and CARTITUDE-1, please refer to the voluntary announcement of the Company dated 7 November 2019.

Shareholders and potential investors of the Company are advised to pay attention to investment risks and exercise in caution when they deal or contemplate dealing in the securities of the Company.

By order of the Board

Genscript Biotech Corporation

Zhang Fangliang

Chairman and Chief Executive Officer

Hong Kong, 8 December 2019

As at the date of this announcement, the executive Directors are Dr. Zhang Fangliang, Ms. Wang Ye and Mr. Meng Jiange; the non-executive Directors are Dr. Wang Luquan, Mr. Pan Yuexin and Ms. Wang Jiafen; and the independent non-executive Directors are Mr. Guo Hongxin, Mr. Dai Zumian and Mr. Pan Jiuan.

* For identification purposes only

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