On January 4, 2024 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, reported a clinical update, including its roadmap for advancing Nana-val’s clinical development in 2024 (Press release, Viracta Therapeutics, JAN 4, 2024, View Source [SID1234638985]). Nana-val (nanatinostat in combination with valganciclovir), is the company’s all-oral investigational therapy targeting Epstein-Barr virus-associated cancers.

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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 (Free ESMO Whitepaper) 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.