A Phase 2 trial of intra-articular RTX for knee OA pain has enrolled its first two patients.The injections were well tolerated and both patients were discharged home after a brief period of observation.Phase 1b data demonstrated significant efficacy supporting RTX as an ideal candidate for long-term control of refractory OA pain: significant pain relief observed in patients with advanced OA disease and sustained pain relief last beyond 6 months and in many cases longer than a year with several patients experiencing more than 3 years of benefit.Sorrento believes RTX has the potential to become a key therapeutic for non-opioid pain with a market potential to exceed $10B by 20251 SAN DIEGO, Dec. 07, 2021 (GLOBE NEWSWIRE) — Sorrento Therapeutics, Inc. (Nasdaq: SRNE, “Sorrento”) today announced that the Phase 2 clinical study of RTX for treating knee pain from osteoarthritis (OA) has begun enrollment. This study is a multi-center, double blind, placebo- and active-controlled study to assess the safety and efficacy of several dose levels of RTX to manage pain in patients associated with moderate-to-severe OA of the knee (clinicaltrials.gov: NCT04885972). Given the durability of the OA pain relief response to RTX demonstrated thus far, the study includes an active comparator (injectable corticosteroid) to demonstrate superiority and duration of the RTX efficacy response. All patients will be followed for at least one year. This Phase 2 study follows the completion of the Phase 1b RTX trial, a double-blinded, placebo-controlled ascending dose study in 94 patients after a single intra-articular administration with one year follow-up (NCT03542838). Patients experienced 6 months of pain relief on average, however several patients continued to report relief 3 years after injection. The magnitude of the difference in the treatment effect (RTX versus control) at 12 weeks was greater than 2 points reduction in WOMAC A1 10-point scale question “pain at walking on flat surface” compared to placebo. 1 Osteoarthritis Market Size, Share, Value, And Competitive Landscape 2021-2026 – MarketWatch About RTX A thousand times “hotter” than pure capsaicin (16 billion Scoville units versus 16M), and with a high affinity for afferent sensory pain nerves, RTX binds to TRPV1 receptors present and selectively ablates the nerve endings responsible for pain signals experienced by patients.2 Delivered peripherally (into the joint space) the transient nerve ending ablation effect can have profound clinical benefits lasting for months to years (as shown in canine studies3). PTVA-OA-001 was a multicenter, placebo-controlled Phase 1b study to assess the safety and define the maximally tolerated dose of RTX administered in the knee joint in patients with moderate to severe pain associated with osteoarthritis of the knee. The study was a dose-escalation trial in which cohorts of patients receive increasing doses of RTX until the maximum tolerated dose (MTD) was achieved. The primary objective of the study was to evaluate the safety of RTX and identify the recommended Phase 3 dose. The secondary objective was to assess the preliminary efficacy of RTX measured by assessing changes in the intensity of pain using the A1 score from the WOMAC, a widely used proprietary validated pain questionnaire. The osteoarthritis treatment market and in particular the Knee Osteoarthritis and injectable markets have historically seen healthy growth and are expected to continue the trend as populations age and present excessive weight. Multiple sources estimate the 2020 market to be around 50M patients and $7B. More information on this completed trial can be found at www.clinicaltrials.gov (NCT03542838). 2 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC398431/ 3 Sorrento Therapeutics (Ark Animal Health) internal data (on file) 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, COVI-AMG™, COVISHIELD™, COVI-MSC™ and COVIDROPS™; and diagnostic test solutions, including COVITRACK™ and COVISTIX™. 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 expectations for Sorrento’s and its subsidiaries’ technologies and product candidates, including, but not limited to, resiniferatoxin (RTX); the clinical potential of RTX, including its potential efficacy and the potential for RTX to address long-term control of refractory osteoarthritis pain; RTX’s potential to reduce or completely eliminate pain over a sustained period of time; expectations that RTX will become a key therapeutic for addressing non-opioid pain; and expectations regarding market size and potential for RTX. 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 RTX; 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 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, 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 ContactDorman FollowwillEmail: mediarelations@sorrentotherapeutics.com Sorrento® and the Sorrento logo are registered trademarks of Sorrento Therapeutics, Inc. G-MAB™, DAR-T™, SOFUSA™, COVI-AMG™, COVISHIELD™, COVIDROPS™, COVI-MSC™, COVITRACK™ 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.