Sorrento Announces First Patient Treated in Phase IB AL Amyloidosis Trial with STI-6129, an Anti-CD38 Antibody-Drug Conjugate

• STI-6129 is an antibody-drug conjugate (ADC) composed of a fully human monoclonal anti-CD38 antibody covalently bound by a proprietary chemical linker to a duostatin tubulin inhibitor.
• Amyloid Light Chain (AL) Amyloidosis is an incurable disease with limited treatment options and the potential for the development of resistance to current approaches.

SAN DIEGO, March 18, 2021 (GLOBE NEWSWIRE) — Sorrento Therapeutics, Inc. (Nasdaq: SRNE, “Sorrento”) today announced that the first patient has been treated in its Phase 1b Amyloid Light Chain (AL) Amyloidosis study of STI-6129, an ADC which uses STI-5171, a fully human monoclonal antibody (mAb) from Sorrento’s G-MAB™ library. This study is being conducted as a multicenter, open-label, dose-escalation clinical trial in patients with advanced relapsed and/or refractory systemic amyloid light chain (AL) amyloidosis with a primary objective to identify a Phase 2 dose for STI-6129 based on its safety, preliminary efficacy and pharmacokinetic profile.

STI-6129 is an ADC with covalently bound duostatin tubulin inhibitors (Duostatin 5) using a proprietary site-specific C-LOCK™ chemical linker designed to reduce the premature systemic release of duostatin and avoid the potential for toxicity, particular ocular toxicity, seen with other ADCs, especially first-generation products. STI-6129 has demonstrated an improved therapeutic index in animal models, as compared to traditional non-selective conjugates. STI-6129 has the potential for being a first-line treatment for amyloidosis as well as second line in those patients who have developed daratumumab resistance, an anti-CD38 mAb alone. STI-6129 binds to different epitopes than daratumumab and the addition of the targeted delivery of the duostatin can potentially manage those patients who have become refractory to such treatments.

“Enrollment into our amyloidosis study with STI-6129 is another important milestone for Sorrento, and although delayed due to COVID-19, we are pleased this study has started,” stated Dr. Henry Ji, Chairman and CEO of Sorrento Therapeutics. “Together with our CD38 CAR-T and DAR-T programs, STI-6129 has the potential to provide additional therapeutic options for patients in need and we are excited to see how it performs in treating patients with AL amyloidosis. We also are looking forward to further evaluating the safety and efficacy of STI-6129 in a soon to start refractory or relapsing multiple myeloma clinical trial.”

About Sorrento Therapeutics, Inc.

Sorrento is a clinical stage, antibody-centric, biopharmaceutical company developing new therapies to treat cancers 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”), clinical stage immuno-cellular therapies (“CAR-T”, “DAR-T™”), antibody-drug conjugates (“ADCs”), and clinical stage oncolytic virus (“Seprehvir™”). Sorrento is also developing potential antiviral therapies and vaccines against coronaviruses, including COVIGUARD™, COVI-AMG™, COVISHIELD™, Gene-MAb™, COVI-MSC™ and COVIDROPS™; and diagnostic test solutions, including COVITRACK™, COVISTIX™ and COVITRACE™.

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 post-herpetic neuralgia. RTX has completed a Phase IB trial for intractable pain associated with cancer and a Phase 1B trial in osteoarthritis patients. SEMDEXA is in a pivotal Phase 3 trial for the treatment of lumbosacral radicular pain, or sciatica. 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 the potential safety and efficacy profile of STI-6129; the use of a C-LOCK chemical linker to reduce premature systemic release of duostatin, and avoid or reduce the toxicity, of STI-6129; the improved therapeutic index of STI-6129 in animal models as compared to traditional ADCs; the potential for STI-6129 to be a first-line treatment for amyloidosis and a second-line treatment in patients who have developed resistance to daratumumab; the potential for STI-6129 to treat treatment-refractory patients; and the plan and expected timing for commencing refractory or relapsing multiple myeloma clinical trials. 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 seeking regulatory approval for STI-6129; 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 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 therapeutic antibody product candidate 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, 2020, and subsequent Quarterly Reports 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

Sorrento Therapeutics
Alexis Nahama, DVM (SVP Corporate Development)
Email: mediarelations@sorrentotherapeutics.com

Sorrento^® and the Sorrento logo are registered trademarks of Sorrento Therapeutics, Inc.

G-MAB™, DAR-T™, SOFUSA™, COVIGUARD™, COVI-AMG™, COVISHIELD™, Gene-MAb™, COVIDROPS™, COVI-MSC™, COVITRACK™, COVITRACE™ and COVISTIX™ are trademarks of Sorrento Therapeutics, Inc.

SEMDEXA™ is a trademark of Semnur Pharmaceuticals, Inc.

ZTlido^® is a registered trademark owned by Scilex Pharmaceuticals Inc.

All other trademarks are the property of their respective owners.

©2021 Sorrento Therapeutics, Inc. All Rights Reserved.