Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. and Levena Biopharma, a Sorrento Company, are to Present Positive Clinical Progress of A166, an Anti-HER2 ADC, in Treating Locally Advanced or Metastatic HER2-Positive Breast Cancer Patients at the ASCO 2022 Annual Meeting

• A166 is an antibody-drug conjugate (ADC) composed of an anti-HER2 antibody conjugated to Duostatin-5, a novel anti-microtubule Auristatin derivative, via a proprietary stable covalent linker.
• The ASCO meeting presentation (ASCO Poster# 415) includes A166 dose expansion data administered in 3-week cycles at doses of 4.8 mg/kg or 6.0 mg/kg in a total of 58 female patients with HER2-positive breast cancer.
• The best ORR was 73.9% (17/23; 95% CI, 51.59 to 89.77) in the 4.8 mg/kg cohort and 68.6% (24/35; 95% CI, 50.71 to 83.15) in the 6.0 mg/kg cohort, respectively.
• Median PFS was 12.3 months (95% CI, 6.00-not reached) in the 4.8 mg/kg cohort and 9.4 months (95% CI, 4.00 to 10.40) in the 6.0 mg/kg cohort, respectively.
• Of 23 patients treated at 4.8 mg/kg cohort, one had a confirmed and sustained complete response (CR) lasting 7+ months.

CHENGDU, China, and SAN DIEGO, June 01, 2022 (GLOBE NEWSWIRE) — Sichuan Kelun-Biotech Biopharmaceutical Co, Ltd. (“Kelun-Biotech”) and Levena Biopharma (“Levena”), a subsidiary of Sorrento Therapeutics, Inc. (Nasdaq: SRNE, “Sorrento”), today announced the planned presentation of A166 data (Abstract #1037 and Poster #415) in patients with HER2-expressing locally advanced or metastatic solid tumors at the 2022 Annual Meeting of ASCO, the American Society of Clinical Oncology, to be held on June 3-7 in Chicago, IL. A166 is a HER2 antibody-drug conjugate (ADC) developed by Kelun-Biotech in a partnership with Levena Biopharma, which provided the patent-protected technologies for the generation and production of A166 in relation to (1) Duostatin-5, a proprietary tubulin inhibitor, (2) K-Lock, a site-specific conjugation technology, and (3) an enzymatically cleavable linker.

As previously reported, in Phase 1 of the study, A166 demonstrated a safety profile that compared favorably to its commercial competitors and potentially superior efficacy as shown by the overall response rate (ORR) of 59.1% and 71.4% in the 4.8 mg/kg cohort and 6.0 mg/kg cohort, respectively, in heavily pretreated patients with HER2-positive breast cancer (data presented at the 2021 ASCO meeting [NCT05311397; J Clin Oncol 39, 2021 (suppl 15; abstr 1024)].

At the upcoming 2022 ASCO meeting, Kelun-Biotech will report updated data from this Phase 1 trial (Abstract #1037 and Poster #415). The Phase 1 dose expansion of the study was conducted in several sites in China and enrolled a total of 58 female patients (n=23 at 4.8 mg/kg and n=35 at 6.0 mg/kg) treated with A166 in 3-week cycles.

• The best ORR was 73.9% (17/23; 95% CI, 51.59 to 89.77) in the 4.8 mg/kg cohort and 68.6% (24/35; 95% CI, 50.71 to 83.15) in the 6.0 mg/kg cohort.
• Median progression free survival (PFS) was 12.3 months (95% CI, 6.00-not reached) in the 4.8 mg/kg cohort and 9.4 months (95% CI, 4.00 to 10.40) in the 6.0 mg/kg cohort.
• Of 23 patients treated in the 4.8 mg/kg cohort, one had a confirmed and sustained CR lasting 7+ months.
• Next generation sequencing was performed on tissue-derived DNA and blood-derived circulating tumor DNA.
• The detailed safety data, RECIST 1.1 response rate, and biomarker analyses will be presented in a poster (#415) at the 2022 ASCO meeting.

About Sichuan Kelun-Biotech Biopharmaceuticals, Co. Ltd.
Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. is a subsidiary of Sichuan Kelun Pharmaceutical Co., Ltd., founded in 2016. Kelun-biotech is committed to developing, and commercializing innovative drugs for the treatment of cancer, autoimmune and other diseases with unmet medical needs.

Kelun-Biotech has developed a fully integrated multi-functional platform which includes R&D, CMC (Chemistry, Manufacturing, and Controls), and clinical development capabilities. Leveraging the platform, the company has built a robust pipeline, 1 I/O monoclonal antibody asset in NMPA NDA stage, 3 assets (including 1 monoclonal antibody and 2 ADCs) in Phase 3 or pivotal clinical trials, and an additional 10 molecules in clinical studies. For more information, please contact: China: klbio_bd@kelun.com, US: bd@kluspharma.com

About Sorrento Therapeutics, Inc. 
Sorrento is a clinical and commercial stage biopharmaceutical company developing new therapies to treat cancer, pain (non-opioid treatments), autoimmune disease and COVID-19. Sorrento’s multimodal, multipronged approach to fighting cancer is made possible by its extensive immuno-oncology platforms, including key assets such as fully human antibodies (“G-MAB™ library”), immuno-cellular therapies (“DAR-T™”), antibody-drug conjugates (“ADCs”), and oncolytic virus (“Seprehvec™”). Sorrento is also developing potential antiviral therapies and vaccines against coronaviruses, including Abivertinib, COVISHIELD™ and COVI-MSC™; and diagnostic test solutions, including COVIMARK™.

Sorrento’s commitment to life-enhancing therapies for patients is also demonstrated by our effort to advance a first-in-class (TRPV1 agonist) non-opioid pain management small molecule, resiniferatoxin (“RTX”), and SP-102 (10 mg, dexamethasone sodium phosphate viscous gel) (SEMDEXA™), a novel, viscous gel formulation of a widely used corticosteroid for epidural injections to treat lumbosacral radicular pain, or sciatica, and to commercialize ZTlido® (lidocaine topical system) 1.8% for the treatment of postherpetic neuralgia (PHN). RTX has been cleared for a Phase II trial for intractable pain associated with cancer and a Phase II trial in osteoarthritis patients. Positive final results from the Phase III Pivotal Trial C.L.E.A.R. Program for SEMDEXA™, its novel, non-opioid product for the treatment of lumbosacral radicular pain (sciatica), were announced in March 2022. ZTlido® was approved by the FDA on February 28, 2018.

For more information visit www.sorrentotherapeutics.com

Forward-Looking Statements
This press release and any statements made for and during any presentation or meeting contain forward-looking statements related to Sorrento Therapeutics, Inc., under the safe harbor provisions of Section 21E of the Private Securities Litigation Reform Act of 1995 and subject to risks and uncertainties that could cause actual results to differ materially from those projected. Forward-looking statements include statements regarding A166, an anti-HER2 ADC; the therapeutic and clinical potential of A166; the potential safety and efficacy of A166, including A166’s potential efficacy against HER2-positive breast cancer; and the potential advantages of A166 over its competitors. Risks and uncertainties that could cause our actual results to differ materially and adversely from those expressed in our forward-looking statements, include, but are not limited to: risks related to Sorrento’s technologies and prospects, including, but not limited to risks related to safety and efficacy for A166; clinical development risks, including risks in the progress, timing, cost, and results of clinical trials and product development programs; risk of difficulties or delays in obtaining regulatory approvals; risks that clinical study results may not meet any or all endpoints of a clinical study and that any data generated from such studies may not support a regulatory submission or approval; risks that prior test, study and trial results may not be replicated in continuing or future studies and trials; risks of manufacturing and supplying drug product; risks related to leveraging the expertise of its employees, subsidiaries, affiliates and partners to assist Sorrento in the execution of its product candidates’ strategies; risks related to the global impact of COVID-19; and other risks that are described in Sorrento’s most recent periodic reports filed with the Securities and Exchange Commission, including Sorrento’s Annual Report on Form 10-K for the year ended December 31, 2021 and subsequent Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission, including the risk factors set forth in those filings. Investors are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date of this release, and we undertake no obligation to update any forward-looking statement in this press release except as required by law.

Media and Investor Relations
Contact: Brian Cooley
Email: mediarelations@sorrentotherapeutics.com

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