Viracta Therapeutics Provides Clinical Update and Outlook for 2024

Speed to market strategy for Nana-val in patients with relapsed or refractory EBV⁺ peripheral T-cell lymphoma supported by complete enrollment of Stage 1, complete enrollment of Stage 2 anticipated in Q1 2024 and engagement with the FDA on potential accelerated approval pathway by mid-2024

Enrollment underway into first split daily dosing cohort in Phase 1b/2 trial of Nana-val in patients with advanced EBV⁺ solid tumors; plans to determine recommended Phase 2 dose and initiate Phase 2 in 2024

SAN DIEGO, Jan. 04, 2024 (GLOBE NEWSWIRE) -- Viracta Therapeutics, Inc. (Nasdaq: VIRX), a clinical-stage precision oncology company focused on the treatment and prevention of virus-associated cancers that impact patients worldwide, today provided a clinical update, including its roadmap for advancing Nana-val’s clinical development in 2024. Nana-val (nanatinostat in combination with valganciclovir), is the company’s all-oral investigational therapy targeting Epstein-Barr virus-associated cancers.

Anticipated Key 2024 Milestones
Pivotal NAVAL-1 study of Nana-val in patients with relapsed or refractory (R/R) Epstein-Barr virus-positive (EBV⁺) lymphomas

• Complete enrollment of Stage 2 in the R/R EBV⁺ peripheral T-cell lymphoma (PTCL) cohort of patients treated with Nana-val (n=11) in the first quarter of 2024.
• Report Stage 1 data from both arms of the R/R EBV⁺ PTCL cohort (in patients treated with nanatinostat, with [n=10] or without [n=10] valganciclovir) in the first half of 2024.
• Meet with the U.S. Food and Drug Administration (FDA) to discuss additional requirements for accelerated approval by mid-2024.
• Enroll patients with R/R EBV⁺ PTCL into the post-Phase 2 expansion cohort to support potential accelerated approval.
• Present Stage 2 data from patients with R/R EBV⁺ PTCL in the second half of 2024.
• Report Stage 1 data from patients with R/R EBV⁺ diffuse large B-cell lymphoma (DLBCL) and R/R EBV⁺ post-transplant lymphoproliferative disorder (PTLD) by year-end 2024.

Phase 1b/2 study of Nana-val in patients with advanced EBV⁺ solid tumors (Study 301)

• Determine the recommended Phase 2 dose (RP2D) by investigating the novel split daily dosing (SDD) regimen at higher dose levels of Nana-val in the second half of 2024.
• Initiate a dose-optimization cohort to confirm the RP2D as part of the study’s Phase 2 expansion by year-end 2024.

“Our primary focus in 2024 is the speed to market strategy for Nana-val in patients with relapsed or refractory EBV-positive PTCL, supported by its accelerating pace of enrollment into Stage 2 and plans to engage with the FDA to discuss Nana-val’s potential accelerated approval pathway in mid-2024,” said Mark Rothera, President and Chief Executive Officer of Viracta. “Additionally, we are encouraged by the progress of the Phase 1b/2 trial of Nana-val in patients with advanced EBV-positive solid tumors, which is now enrolling and treating patients with the novel split daily dosing regimen, and we remain on track to expand the study into Phase 2 in 2024. The growing clinical data together with the recent orphan drug designation granted by FDA for the treatment of nasopharyngeal carcinoma further positions Nana-val as a tumor-agnostic approach to address the high unmet medical need for patients with EBV-associated cancers, including both lymphomas and solid tumors. With an anticipated cash runway into 2025, we are well-positioned for a successful 2024.”

Recent Clinical Trial Updates
Pivotal NAVAL-1 study of Nana-val in patients with R/R EBV⁺ lymphomas

• Completed enrollment of Stage 1 in the R/R EBV⁺ PTCL cohort of patients, and enrollment into Stage 2 continues to accelerate, as nearly half of the Stage 2 patients have been enrolled.
• The protocol was amended to additionally enable enrollment of second-line R/R EBV⁺ DLBCL patients and R/R EBV⁺ PTLD patients, including pediatric EBV⁺ PTLD patients ≥ 12 years of age.

Phase 1b/2 study of Nana-val in patients with advanced EBV⁺ solid tumors (Study 301)

• Initiated enrollment of the sixth dose cohort of patients with recurrent or metastatic (R/M) EBV⁺ nasopharyngeal carcinoma (NPC) evaluating the new SDD regimen.
• In December 2023, the FDA granted an orphan drug designation (ODD) to Nana-val for the treatment of NPC, the fifth ODD granted to Nana-val by the FDA and the seventh ODD for Nana-val globally.
• Confirmed partial responses without dose-limiting toxicities through the initial five dose cohorts. Further, new preclinical data presented at ESMO Asia Congress 2023 support continued dose-escalation to enhance Nana-val’s antitumor activity.
  • Best responses through the fifth dose cohort included two confirmed partial responses and five stable diseases out of 17 patients.

About NAVAL-1
NAVAL-1 (NCT05011058) is a global, multicenter, clinical trial of Nana-val in patients with relapsed or refractory (R/R) Epstein-Barr virus-positive (EBV⁺) lymphoma. This trial employs a Simon two-stage design where, in Stage 1, participants are enrolled into one of three indication cohorts based on EBV⁺ lymphoma subtype. If two objective responses are achieved within a lymphoma subtype in Stage 1 (n=10), then additional patients will be enrolled in Stage 2 for a total of 21 patients. EBV⁺ lymphoma subtypes demonstrating promising antitumor activity in Stage 2 may be further expanded following discussion with regulators to potentially support registration.

About the Phase 1b/2 Study of Nana-val in Patients with Advanced EBV⁺ Solid Tumors (Study 301)
This Phase 1b/2 trial (NCT05166577) is an open-label, multinational clinical trial evaluating Nana-val alone and in combination with pembrolizumab. The Phase 1b dose escalation part is designed to evaluate safety and to select the recommended Phase 2 dose (RP2D) of Nana-val in patients with recurrent or metastatic (R/M) Epstein-Barr virus-positive (EBV⁺) nasopharyngeal carcinoma (NPC). Along with the U.S. Food and Drug Administration’s Project Optimus initiative, at the start of Phase 2, up to 40 patients with R/M EBV⁺ NPC will be randomized to receive either the RP2D or a dose level below the RP2D in a dose-optimization cohort. Once the RP2D has been confirmed, up to 60 patients with R/M EBV⁺ NPC will be randomized to receive Nana-val at the RP2D with or without pembrolizumab to further evaluate antitumor activity, safety and tolerability, pharmacokinetics, and potential pharmacodynamic biomarkers. 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. Ongoing trials include a pivotal, global, multicenter, open-label Phase 2 basket trial in multiple subtypes of relapsed or refractory (R/R) EBV⁺ lymphoma (NAVAL-1) as well as a multinational Phase 1b/2 clinical trial in patients with recurrent or metastatic (R/M) EBV⁺ NPC and other advanced EBV⁺ solid tumors.

About EBV-Associated Cancers
Approximately 90% of the world's adult population is infected with 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-positive (EBV⁺) lymphomas. EBV is estimated to be associated with approximately 2% of the global cancer burden including lymphoma, nasopharyngeal carcinoma (NPC), and gastric cancer.

About Viracta Therapeutics, Inc.
Viracta is a clinical-stage 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 or refractory (R/R) Epstein-Barr virus-positive (EBV⁺) lymphoma (NAVAL-1), as well as a multinational, open-label Phase 1b/2 clinical trial for the treatment of patients with recurrent or metastatic (R/M) EBV⁺ nasopharyngeal carcinoma (NPC) and other advanced 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 clinical trials and updates regarding the same, the Company’s expectations related to the FDA submission process and timelines, expectations regarding our target patient populations, and expectations regarding our cash runway. 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 supply nanatinostat, valganciclovir, and pembrolizumab for clinical testing; and Viracta's estimates regarding its ability to fund ongoing operations into 2025, future expenses, capital requirements, and need for additional financing in the future.

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.