On December 7, 2020 Viracta Therapeutics, Inc. (Viracta or the Company), a precision oncology company targeting virus-associated malignancies, reported recent clinical and regulatory developments regarding its lead program for the treatment of relapsed/refractory (R/R) EBV+ lymphomas (Press release, Viracta Therapeutics, DEC 7, 2020, View Source [SID1234572391]).
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At the 62nd American Society of Hematology (ASH) (Free ASH Whitepaper) Annual Meeting, Dr. Pierluigi Porcu of Sidney Kimmel Cancer Center, Thomas Jefferson University, presented updated data from Viracta’s ongoing clinical trial evaluating its all-oral combination regimen of nanatinostat and valganciclovir for the treatment of patients with R/R EBV+ lymphoma that had failed one or more prior therapies and lacked treatment options.
As of the data cutoff (October 27, 2020), 46 patients were enrolled (B-cell non-Hodgkin lymphoma (B-NHL; n=10), T/NK-cell non-Hodgkin lymphoma (T/NK-NHL; n=15), immunodeficiency-associated lymphoproliferative disorder (IA-LPD; n=13) and Hodgkin lymphoma (HL: n=8). The number of median prior therapies was 2; 80% were refractory to their last prior therapy and 80% had exhausted all prior therapies.
Key results include:
Complete responses were observed across multiple EBV+ lymphoma subtypes (diffuse large B-cell lymphoma (DLBCL), T/NK-NHL and IA-LPD); preliminary efficacy in Phase 2 is consistent with Phase 1b results
Highly active in T/NK-NHL (n=10) with an overall response rate (ORR) of 80% (8/10) and complete response rate (CR) of 40% (4/10)
Encouraging activity in DLBCL (n=6) with an ORR of 66% (4/6) and a CR of 33% (2/6); both CR’s were in patients refractory to first-line R-CHOP
Generally well-tolerated; most common Grade 3/4 toxicities were reversible cytopenias with limited extra-hematologic toxicity
Three patients (2 T/NK-NHL, 1 Hodgkin lymphoma) previously ineligible for immunotherapy approaches were withdrawn from the trial to undergo stem cell transplantation and CAR-T cell therapy respectively
Median duration of response of 10.4 months
In November 2020, Viracta held an End of Phase 2 Meeting with the United States Food and Drug Administration (FDA) to address various nonclinical and clinical topics. Based on the outcome of this meeting, the Company intends to initiate a global registration trial in R/R EBV+ lymphomas in 1H 2021. This trial is designed to support multiple potential marketing approvals across the various subtypes of EBV+ lymphoma. An End of Phase 2 Meeting with the United States FDA to address chemistry, manufacturing and controls is planned for December 2020, and preliminary comments from the Agency indicate alignment in key areas.
Lisa Rojkjaer, M.D., Chief Medical Officer of Viracta commented, "EBV+ lymphoma is an area of high unmet medical need, with adverse survival outcomes reported with standard of care regimens and no approved therapies. The encouraging efficacy and safety profile observed thus far in these highly refractory patients underscores the potential of this oral combination regimen of nanatinostat with valganciclovir for the treatment of patients with recurrent disease. We look forward to advancing our clinical development program in EBV+ lymphoma into its next stages."
Ivor Royston, M.D., President and Chief Executive Officer of Viracta added, "Alignment with the FDA on our registrational trial design and manufacturing plans provide clarity about our development pathway to potential marketing approval for our combination product candidate. We believe the FDA’s support for our registrational trial design is a reflection of the Agency’s recognition of the unmet medical need of patients with EBV+ lymphoma and the promising potential of our inducible synthetic lethality approach. In addition, with our recently announced merger agreement with Sunesis Pharmaceuticals and significant financings, we are well capitalized with significant momentum to advance this and our EBV+ solid tumor program forward in 2021."
Details of ASH (Free ASH Whitepaper) Presentation
Abstract number: 624
Title: Oral Nanatinostat (Nstat) and Valganciclovir (VGCV) in Patients with Recurrent Epstein-Barr Virus (EBV)-Positive Lymphomas: Initial Phase 2 Results
Presenter: Pierluigi Porcu, MD, Sydney Kimmel Cancer Center, Thomas Jefferson University
Session: Hodgkin lymphoma and T/NK cell lymphoma—Clinical studies
A copy of the presentation can be accessed by visiting the "News/Media" section of the Viracta website: View Source
Viracta’s Planned Merger with Sunesis Pharmaceuticals
On November 30, 2020, Sunesis Pharmaceuticals, Inc. (Nasdaq: SNSS) and Viracta announced the parties entered into a definitive merger agreement (the Merger Agreement) pursuant to which Viracta will combine with Sunesis in an all-stock transaction (the Merger). The merged company will focus on the advancement and expansion of Viracta’s clinical stage, precision oncology pipeline targeting virus-associated malignancies, including Viracta’s lead program for the treatment of EBV+ R/R lymphomas. Upon completion of the Merger, the combined company will operate under the name Viracta Therapeutics, Inc. and intends to be listed on the Nasdaq Global Market under the ticker symbol "VIRX".
Under the terms of the Merger Agreement, pending stockholder approval of the transaction, Viracta will merge with a wholly owned subsidiary of Sunesis, and stockholders of Viracta will receive shares of newly issued Sunesis common stock. Viracta stockholders are expected to own approximately 86% and Sunesis stockholders will own approximately 14% of the combined company on a fully diluted basis using the treasury stock method. The percentage of the combined company that Sunesis stockholders will own as of the close of the Merger may be subject to adjustment based on Sunesis’ net cash.
The Merger Agreement has been unanimously approved by the Board of Directors of each company. The transaction is expected to close in the first quarter of 2021, subject to approvals by stockholders of each company and other customary closing conditions.
A more complete description of the terms of and conditions of the merger can be found in Sunesis’ Form 8-K filed on November 30, 2020 with the Securities and Exchange Commission (SEC) and in the Merger Agreement, which is filed as an exhibit to that Form 8-K.
About Nanatinostat
Nanatinostat (VRx-3996) is an orally available histone deacetylase (HDAC) inhibitor being developed by Viracta. Nanatinostat is selective for specific isoforms of Class I HDACs, which is key to inducing latent viral genes which are epigenetically silenced in EBV-associated malignancies. The nanatinostat and valganciclovir combination is being investigated in EBV+ lymphomas in an ongoing Phase 2 clinical trial [NCT03397706].
Viracta has received Fast Track designation from the FDA for the nanatinostat and valganciclovir combination in R/R EBV+ lymphomas, as well as orphan drug designations for the treatment of post-transplant lymphoproliferative disorder, plasmablastic lymphoma, and T-cell lymphomas.