Viracta Therapeutics Announces Preliminary Dose-Ranging Data from the Phase 1b/2 Trial of Nana-val in Advanced Epstein-Barr Virus-Positive (EBV ) Solid Tumors at the ESMO Immuno-Oncology Congress

SAN DIEGO, Nov. 30, 2022 (GLOBE NEWSWIRE) -- Viracta Therapeutics, Inc. (Nasdaq: VIRX), a precision oncology company focused on the treatment and prevention of virus-associated cancers that impact patients worldwide, today reported preliminary dose-ranging data from the first two dose levels of the dose escalation part of the Phase 1b/2 study of Nana-val in patients with EBV⁺ recurrent/metastatic nasopharyngeal carcinoma (R/M NPC). The data are featured in an abstract accepted for a poster presentation at the European Society for Medical Oncology Immuno-Oncology Congress (ESMO-IO), which is taking place both virtually and in-person at the Palexpo Exhibition Centre in Geneva, Switzerland, from December 7 – 9, 2022.

The Phase 1b/2 trial’s first two dose levels enrolled seven patients with EBV⁺ R/M NPC, six of whom were evaluable for response as of the abstract’s data cut-off date (September 15, 2022). At the time of enrollment, patients had received a median of two prior systemic therapies. All patients were refractory to their last therapy with bone (6/7), liver (5/7), and lung (3/7) metastases.

Key data reported in the abstract include:

• Nana-val was well tolerated with no dose limiting toxicities (DLTs) reported. Most common Grade 1-2 AEs were fatigue, nausea, and increased creatinine (n=3 each).
• Two of six evaluable patients achieved stable disease (SD) per RECIST v1.1 criteria.
• Plasma EBV DNA titers decreased or remained stable in both patients achieving SD, while rising in patients with progressive disease.
  

“We initiated this study earlier this year, and this abstract reports the first preliminary data on our all-oral combination regimen in patients with advanced Epstein-Barr virus-positive NPC, where few treatment options are available,” said Lisa Rojkjaer, M.D., Chief Medical Officer of Viracta. “Starting with the recommended Phase 2 dose from our Phase 1b/2 study in lymphoma, the combination of nanatinostat and valganciclovir was thus far well-tolerated in the initial dose escalation cohorts, with no DLTs reported. Dose escalation continues as we evaluate optimizing the use of both agents in the solid tumor setting. We look forward to the advancement of this study to determine the recommended Phase 2 dose.”

As previously reported, the Phase 1b/2 trial is currently progressing through its third dose escalation cohort, with enrollment in the third dose level completed. Further safety data from the third dose level will be presented in the abstract’s corresponding poster at ESMO-IO. Viracta recently amended the trial protocol to include additional dose levels in the Phase 1b dose escalation portion, which is designed to determine the optimal recommended Phase 2 dose (RP2D). The company anticipates initiating the Phase 2 randomized expansion portion of the Phase 1b/2 trial in the second half of 2023.

Additional details related to the abstract and upcoming poster, entitled, A Phase 1b/2 Study of Nanatinostat (Nstat) Plus Valganciclovir (VGCV) in Advanced Epstein-Barr Virus Positive (EBV⁺) Solid Tumors and with Pembrolizumab (PEM) in Recurrent/Metastatic Nasopharyngeal Carcinoma (R/M NPC), are shown below.

Presentation Number: 156P
Poster Session Date: December 8, 2022
Poster Session Time: 12:30 p.m. CET

The abstract is currently available for viewing on the congress website. A copy of the poster will be available on the "Events and Webcasts" section of the Viracta website following the conclusion of the congress.

About the Phase 1b/2 Trial of Nana-val in EBV⁺ R/M NPC and Other EBV⁺ Solid Tumors
This Phase 1b/2 trial (NCT05166577) is an open-label, multinational trial evaluating Nana-val alone and in combination with pembrolizumab. The Phase 1b dose escalation portion is designed to evaluate safety and to determine the recommended Phase 2 dose (RP2D) of Nana-val in patients with EBV⁺ RM-NPC. In Phase 2, up to sixty patients with EBV⁺ RM-NPC will be randomized to receive Nana-val at the RP2D with or without pembrolizumab to evaluate safety, overall response rate, and potential pharmacodynamic markers. Additionally, patients with other advanced EBV⁺ solid tumors will be enrolled to receive Nana-val at the RP2D in a Phase 1b dose expansion cohort.

About Nana-val (Nanatinostat and Valganciclovir)

Nanatinostat is an orally available histone deacetylase (HDAC) inhibitor being developed by Viracta. Nanatinostat is selective for specific isoforms of Class I HDACs, which are key to inducing viral genes that are epigenetically silenced in Epstein-Barr virus (EBV)-associated malignancies. Nanatinostat is currently being investigated in combination with the antiviral agent valganciclovir as an all-oral combination therapy, Nana-val, in various subtypes of EBV-associated malignancies.

About EBV-Associated Cancers

Approximately 90% of the world's adult population is infected with Epstein-Barr virus (EBV). Infections are commonly asymptomatic or associated with mononucleosis. Following infection, the virus remains latent in a small subset of cells for the duration of the patient's life. Cells containing latent virus are increasingly susceptible to malignant transformation. Patients who are immunocompromised are at an increased risk of developing EBV⁺ lymphomas. EBV is estimated to be associated with approximately 2% of the global cancer burden including lymphoma, nasopharyngeal carcinoma and gastric cancer.

About Viracta Therapeutics, Inc.

Viracta is a precision oncology company focused on the treatment and prevention of virus-associated cancers that impact patients worldwide. Viracta’s lead product candidate is an all-oral combination therapy of its proprietary investigational drug, nanatinostat, and the antiviral agent valganciclovir (collectively referred to as Nana-val). Nana-val is currently being evaluated in multiple ongoing clinical trials, including a pivotal, global, multicenter, open-label Phase 2 basket trial for the treatment of multiple subtypes of relapsed/refractory Epstein-Barr virus-positive (EBV⁺) lymphoma (NAVAL-1), as well as a multinational, open-label Phase 1b/2 trial for the treatment of EBV⁺ recurrent or metastatic nasopharyngeal carcinoma and other EBV⁺ solid tumors. Viracta is also pursuing the application of its “Kick and Kill” approach in other virus-related cancers.

For additional information please visit www.viracta.com.

Forward Looking Statements

This communication contains "forward-looking" statements within the meaning of the Private Securities Litigation Reform Act of 1995, including, without limitation, statements regarding: the details, timeline and expected progress for Viracta's ongoing and anticipated trials and updates regarding the same, including the Phase 1b/2 trial of Nana-val in EBV⁺ solid tumors. Risks and uncertainties related to Viracta that may cause actual results to differ materially from those expressed or implied in any forward-looking statement include, but are not limited to: Viracta's ability to successfully enroll patients in and complete its ongoing and planned clinical trials; Viracta's plans to develop and commercialize its product candidates, including all oral combinations of nanatinostat and valganciclovir; the timing of initiation of Viracta's planned clinical trials; the timing of the availability of data from Viracta's clinical trials; previous preclinical and clinical results may not be predictive of future clinical results; the timing of any planned investigational new drug application or new drug application; Viracta's plans to research, develop and commercialize its current and future product candidates; the clinical utility, potential benefits and market acceptance of Viracta's product candidates; Viracta's ability to manufacture or supplying nanatinostat, valganciclovir and pembrolizumab for clinical testing; Viracta's ability to identify additional products or product candidates with significant commercial potential; developments and projections relating to Viracta's competitors and its industry; the impact of government laws and regulations; Viracta's ability to protect its intellectual property position; and Viracta's estimates regarding future expenses, capital requirements and need for additional financing in the future.

These risks and uncertainties may be amplified by the COVID-19 pandemic, which has caused significant economic uncertainty. If any of these risks materialize or underlying assumptions prove incorrect, actual results could differ materially from the results implied by these forward-looking statements. Additional risks and uncertainties that could cause actual outcomes and results to differ materially from those contemplated by the forward-looking statements are included under the caption "Risk Factors" and elsewhere in Viracta's reports and other documents that Viracta has filed, or will file, with the SEC from time to time and available at www.sec.gov.

The forward-looking statements included in this communication are made only as of the date hereof. Viracta assumes no obligation and does not intend to update these forward-looking statements, except as required by law or applicable regulation.

Investor Relations Contact:
Ashleigh Barreto
Head of Investor Relations & Corporate Communications
Viracta Therapeutics, Inc.
abarreto@viracta.com

SOURCE Viracta Therapeutics, Inc.