An Interventional Decentralized Phase 2, Randomized, Double-Blind, 2-Arm Study to Investigate the Efficacy and Safety of Orally Administered Nirmatrelvir/Ritonavir Compared with Placebo/Ritonavir in Participants with Long COVID

This decentralized trial is a Phase 2, 1:1 randomized, double-blind, superiority, placebo-controlled study in an anticipated 100 non-hospitalized highly symptomatic adult participants with long COVID. It seeks to determine the efficacy, safety, and tolerability of 15 days of Paxlovid (nirmatrelvir/ritonavir), an anti-viral agent, compared with placebo plus ritonavir. The hypothesis is that viral persistence contributes to long COVID in some patients and nirmatrelvir/ritonavir compared with placebo/ritonavir can improve general health status in participants with long COVID. The study will also seek immune signatures associated with treatment response (overseen by Professor Akiko Iwasaki).
The decentralized study does not require site visits, and participants in all 48 states including the District of Columbia, who meet entry criteria can enroll. It is designed to make it convenient to participate. The study drugs will be delivered to the participant's designated address.
Long COVID is also known as post-acute sequelae of SARS-CoV-2 (PASC).

Start Date14 Apr 2023

Sponsor / Collaborator

Yale University

[+1]

ChiCTR2300068643

/ RecruitingPhase 4IIT

A randomized, single center, open label study for azvudine vs Paxlovid treatment for severe COVID-19 patients

Start Date16 Jan 2023

Sponsor / Collaborator

Xiang'an Hospital Affiliated to Xiamen University

NCT05545319

/ WithdrawnPhase 2

AN INTERVENTIONAL EFFICACY AND SAFETY, PHASE 2, DOUBLE-BLIND, 2-ARM STUDY TO INVESTIGATE ORALLY ADMINISTERED NIRMATRELVIR/RITONAVIR COMPARED WITH PLACEBO/RITONAVIR FOR THE TREATMENT OF SEVERE COVID-19 IN HOSPITALIZED PARTICIPANTS WHO ARE IMMUNOCOMPROMISED OR AT INCREASED RISK FOR SEVERE COVID-19 OUTCOMES

A Study to Learn About the Medicine Called Nirmatrelvir Used in Combination With Ritonavir in People with Weakened Immune Systems or at Increased Risk for Poor Outcomes who are Hospitalized Due to Severe COVID-19

Start Date13 Dec 2022

Sponsor / Collaborator

Pfizer Inc.

100 Clinical Results associated with Nirmatrelvir

100 Translational Medicine associated with Nirmatrelvir

100 Patents (Medical) associated with Nirmatrelvir

1,362

Literatures (Medical) associated with Nirmatrelvir

01 Mar 2026·BIOORGANIC & MEDICINAL CHEMISTRY LETTERS

Identification of flavonoid-based small molecule inhibitors with dual-targeting capability against RdRp and Mpro of SARS-CoV-2

Article

Author: Duan, Xuhong ; Su, Yanlei ; Zhang, Jing ; Wu, Honghai ; Zhao, Jianyuan ; Sun, Dianxing ; Wang, Yujia ; Guo, Keyu ; Cen, Shan

Due to issues of high transmissibility, immune evasion, and drug resistance in SARS-CoV-2 variants, there is an urgent need for novel antiviral drugs. Plant-derived flavonoids such as baicalein (EC₅₀ = 4.5 μM) and baicalin (EC₅₀ = 9.0 μM) exhibit broad-spectrum antiviral potential via RNA-dependent RNA polymerase (RdRp) inhibition. Based on this, our study identified two derivatives through pharmacophore alignment between flavonoid scaffolds and the main protease (Mpro) inhibitor 13b: a psoralen-derived lignan (Comp.1) and a novel isoflavone analog (Comp.2), with dual-targeting capability against SARS-CoV-2 RdRp and Mpro. Computational docking elucidated the binding interactions of compounds with RdRp, Mpro, and the L50F/E166V double mutant Mpro. In vitro assays demonstrated that Comp.1 exhibited micromolar-range inhibitory effects on both RdRp (EC₅₀: 25.45 μM) and Mpro (IC₅₀: 125.4 μM), outperforming Comp.2. Both compounds maintained inhibitory activity against the PF07321332-resistant L50F/E166V double mutant Mpro, with IC₅₀ fold-change values of 1.23 and 1.18, respectively, compared to an 8.62-fold reduction for PF07321332. However, ADMET evaluation indicated that although compounds met basic physicochemical criteria (including molecular weight, TPSA, and compliance with Lipinski's Rule of Five), they still presented critical toxicological liabilities, including high genotoxicity risk (Comp.1: 0.838 probability) and CYP3A4 inhibition (>0.97), necessitating extensive structural optimization. This study confirms that flavonoid derivatives represent promising starting points for developing resistance-aware antiviral agents, though their current profiles classify them as early-stage leads requiring substantial optimization.

05 Feb 2026·AMERICAN JOURNAL OF EPIDEMIOLOGY

Impact of time zero designation on estimated COVID-19 antiviral effectiveness in observational studies

Article

Author: Bui, David ; Bajema, Kristina L ; Rajeevan, Nallakkandi ; Lin, Hung-Mo ; Bohnert, Amy S B ; Maciejewski, Matthew L ; Aslan, Mihaela ; Smith, Valerie A ; Hynes, Denise M ; Huang, Yuan ; Berry, Kristin ; Ioannou, George N ; Yan, Lei ; Li, Yuli

Abstract:

In a well-designed clinical trial, time zero is when eligibility is determined, treatment is assigned, follow-up time begins, and each of these elements is aligned. Attaining this alignment can be challenging in observational studies, risking potential bias. We compared the impact of different time zero designations on the estimated effectiveness of nirmatrelvir-ritonavir for COVID-19. We identified US veterans who tested positive for SARS-CoV-2 from April 2022 to March 2023 and compared nirmatrelvir-ritonavir vs no treatment using 5 time zero approaches: (1a) test-date (treated) vs test-date (untreated) allowing treatment on days 0-5 with matching, (1b) day 0 only with matching, or (1c) days 0-5 with a clone-censor-weight method; (2) treatment date vs test-date with matching; or (3) treatment date vs matched index date. Thirty-day incidence of hospitalization or death was lower in the nirmatrelvir-ritonavir group than the no treatment group for all time zero approaches. Estimated risk differences (95% CI) were larger for approaches 1a (−2.10% [−2.35 to −1.86]), 1b (−2.03% [−2.40 to −1.84]), and 2 (−2.26% [−2.47 to −2.02]); −1.80% (−1.89 to −1.45) for approach 3; and lowest for approach 1c (−0.95% [−1.11 to −0.75]). Different time zero designations can influence effect estimates and should be carefully considered when designing pharmacoepidemiology studies.

01 Feb 2026·DRUG METABOLISM AND DISPOSITION

Absorption, distribution, metabolism, and excretion tactics toward the expedited discovery and development of the severe acute respiratory syndrome coronavirus-2 main protease inhibitor nirmatrelvir

Review

Author: Obach, R Scott ; Walker, Gregory S ; Eng, Heather ; Dantonio, Alyssa L ; Kalgutkar, Amit S ; Boras, Britton ; Di, Li ; Kadar, Eugene P

The severe acute respiratory syndrome coronavirus-2 main protease inhibitor PF-07321332 (nirmatrelvir), in combination with ritonavir (Paxlovid), has been approved by the US Food and Drug Administration as an oral treatment option for coronavirus disease 2019 patients. In this perspective, we share the expediated absorption, distribution, metabolism, and excretion strategies, which were incorporated as part of discovery efforts, to design orally active severe acute respiratory syndrome coronavirus-2 main protease inhibitors. PF-07321332 (nirmatrelvir) emerged as a potential oral clinical candidate within ∼ 6 months from the time discovery efforts were first initiated. The review also delves into a discussion around the successful use of quantitative fluorine-19 nuclear magnetic resonance spectroscopy in the characterization of the human mass balance and excretion pathways of nirmatrelvir. Human absorption, distribution, metabolism, and excretion data that emerged from the fluorine-19 nuclear magnetic resonance study were used to support the Emergency Use Authorization and new drug application filing, which was accepted by regulatory agencies worldwide. Efficient operational and technical strategies, incorporating the elements of speed without sacrificing data quality, which were crucial to the success of the program, are highlighted. SIGNIFICANCE STATEMENT: This perspective discusses the expedited absorption, distribution, metabolism, and excretion efforts utilized in the discovery and development of the orally active severe acute respiratory syndrome coronavirus-2 main protease inhibitor nirmatrelvir, which in combination with the cytochrome P450 3A inhibitor ritonavir (Paxlovid), is used in the oral treatment of COVID-19. Paxlovid was granted an Emergency Use Authorization by global regulatory agencies in less than 2 years from the initiation of the discovery program and has since been fully approved by the US Food and Drug Administration.

236

News (Medical) associated with Nirmatrelvir

19 Feb 2026

·www.biospace.com

Traws Pharma Completes Analysis of Ratutrelvir Clinical Study in PAXLOVID®-Eligible and Ineligible COVID-19 Patients and Provides Updates for Additional Indication for Tivoxavir Marboxil as a Prophylactic Treatment for Seasonal Influenza

Completed clinical results with ratutrelvir confirm a differentiated pro PAXLOVID ® with fewer adverse events and no viral rebounds with equivalent time to sustained symptom resolution; results were recapitulated in PAXLOVID ® -ineligible patients, representing a significant population with no effective treatment options Pre-clinical analysis of tivoxavir marboxil tablets demonstrated significantly increased exposure compared to a prototype formulation with predicted 28-day protection in humans from influenza infections against a wide range of seasonal and pandemic variants PK study of compressed tivoxavir marboxil tablets submitted under open IND in Australia and preparations are underway for a Human Influenza Prophylaxis Challenge Study in the UK NEWTOWN, Pa., Feb. 19, 2026 (GLOBE NEWSWIRE) -- Traws Pharma, Inc. (NASDAQ: TRAW, “Traws Pharma”, “Traws” or “the Company”), a clinical-stage biopharmaceutical company developing novel therapies to target critical threats to human health from respiratory viral diseases, today announced the completion of the clinical analysis of its 90-patient, open-label Phase 2 study of ratutrelvir, an investigational oral, ritonavir-free Mpro/3CL protease inhibitor, versus PAXLOVID ® in patients with mild-to-moderate COVID-19, together with a single arm in PAXLOVID ® -ineligible subjects. Patients ineligible to receive PAXLOVID ® are frequently at elevated risk for severe disease and require suitable, safe and effective treatment options. Ratutrelvir has the potential to address this gap in care and may be a valuable therapeutic option. Ratutrelvir Update Designed as an active-controlled comparator trial versus PAXLOVID ® (nirmatrelvir/ritonavir), the study evaluated patient-reported symptom outcomes, safety, and real-world usability. A separate treatment arm was comprised of patients ineligible for ritonavir-boosted regimens due to contraindications or clinically significant drug–drug interactions. Patients in the ratutrelvir arm received ratutrelvir 600 mg orally once daily for 10 days, while patients in the comparator arm received PAXLOVID ® , administered as nirmatrelvir 300 mg twice daily plus 100mg ritonavir twice daily for 5 days, consistent with approved prescribing information. Patients receiving ratutrelvir who were ineligible for PAXLOVID ® reported fewer treatment-related adverse events (3 events in 30 subjects, 10%) compared to subjects receiving PAXLOVID ® , (7 events in 30 subjects, 23.3%), and symptoms resolved more quickly in subjects taking ratutrelvir who were ineligible for PAXLOVID ® , compared to PAXLOVID ® treatment (HR, 1.31; 95% CI, 0.78-2.20, p =0.018). “From a clinical perspective, the completed data analysis confirms that ratutrelvir may provide a meaningful benefit across a broader range of patients, including those who are unable to receive ritonavir-boosted therapy,” commented Robert R. Redfield, MD, Chief Medical Officer of Traws Pharma. “The favorable tolerability profile, together with a shortened time to symptom resolution and the absence of viral rebound events in ratutrelvir-treated patients, encourages and supports the continued clinical evaluation of ratutrelvir in both acute COVID-19 and in studies designed to better understand its potential impact on longer-term outcomes.” “The combination of early and sustained symptom improvement, extended dosing duration, absence of viral rebound observed to date, and favorable tolerability supports the strategic hypothesis that ratutrelvir may have utility in reducing post-acute sequelae of SARS-CoV-2 infection (Long COVID),” commented Dr. Redfield . “By enabling earlier and potentially more complete viral clearance, without the limitations associated with ritonavir boosting, ratutrelvir may offer a differentiated approach to both acute COVID-19 treatment and prevention of longer-term complications”. Tivoxavir Marboxil Update The Company additionally announced progress in advancing an additional indication for tivoxavir marboxil (TXM), a potential best in class CAP-dependent endonuclease inhibitor, as a once-monthly, single oral tablet for prevention of seasonal influenza. In prior Phase 1 studies in healthy volunteers, an unformulated powder-in-capsule formulation provided blood levels exceeding 3X EC 50 against a basket of common seasonal influenza variants up to 22 days after drug administration. A tablet formulation has been evaluated pre-clinically and demonstrated a 30% increase in exposure compared to the unformulated prototype. “Modelling of these data suggests that the tablet formulation should provide 28-day coverage, enabling a once-a-month prophylactic treatment,” commented C. David Pauza, PhD, Chief Science Officer of Traws Pharma. “We intend to advance these findings into a healthy volunteer study to be conducted under an open IND in Australia and, if the extended exposure is confirmed, we intend to progress TXM into a Seasonal Human Influenza Virus Prophylaxis Challenge Study,” Dr. Pauza continued. Separately, the FDA informed the Company that its US IND for tivoxavir marboxil was being placed on clinical hold due to concerns with the mutagenicity data package. The FDA intends to communicate its concerns formally, together with suggested mitigation steps, by March 16, 2026. Dr. Redfield commented, “This IND application was originally filed to enable a complete review by the Biomedical Advanced Research and Development Authority (BARDA) of the Company’s application for inclusion in the strategic stockpile for the treatment of avian influenza. While the clinical hold does not directly impact ongoing and planned studies outside of the United States, Traws Pharma appreciates the FDA concern and is working to mitigate this issue in our clinical development plan.” “Collectively, the advancement of our antiviral portfolio provides a number of significant value inflection points and could provide treatment and prevention options for clinically important viral diseases,” commented Iain Dukes, MA, DPhil, Chief Executive Officer of Traws Pharma. About Ratutrelvir Ratutrelvir is an investigational oral, small molecule Mpro (3CL protease) inhibitor designed to be a broadly acting treatment for SARS-CoV-2/COVID-19 that is used without ritonavir. It has demonstrated in vitro activity against a range of virus strains. Preclinical and Phase 1 studies show that ratutrelvir does not require co-administration with a metabolic inhibitor, such as ritonavir, which could avoid ritonavir-associated drug-drug interactions 1 , and potentially enable wider patient use. Phase 1 data also show that ratutrelvir’s pharmacokinetic (PK) pro maintenance of target blood plasma levels approximately 13 times above the EC 50 using the target Phase 2 dosing regimen of 600 mg/day for ten days, which may also reduce the likelihood of clinical rebound and, consequently, reduce the risk for Long COVID 2 . Industry data indicate that COVID treatment represents a potential multi-billion dollar market opportunity 3 . About Tivoxavir Marboxil Tivoxavir marboxil (TXM) is an investigational oral, small molecule CAP-dependent endonuclease inhibitor designed to be administered as a single-dose for the treatment of bird flu and seasonal influenza. It has shown potent in vitro activity against a range of influenza strains in preclinical studies, including a human isolate of the highly pathogenic avian flu H5N1 (bird flu). Consistent, positive preclinical data from three animal species indicate that a single dose of TXM demonstrated a therapeutic effect against H5N1 bird flu. Seasonal influenza represents an estimated multi-billion dollar antiviral market opportunity, largely driven by global health organizations, practice guidelines and government tenders and inclusion in drug stock piling initiatives 4,5 , with upside potential from potential pandemic flu outbreaks including H5N1 bird flu. We believe that these data support further development of TXM as a treatment for bird flu. Source information Carly Herbert et al. (2025) Clinical Infectious Diseases. Pfizer Inc. annual report on Form 10-K for the fiscal year ended December 31, 2025, filed with the U.S. Securities and Exchange Commission on February 3, 2026 Per link TRAW data on file Third-party products mentioned herein are the trademarks of their respective owners. About Traws Pharma, Inc. Traws Pharma is a clinical stage biopharmaceutical company dedicated to developing novel therapies to target critical threats to human health in respiratory viral diseases. Traws integrates antiviral drug development, medical intelligence and regulatory strategy to meet real world challenges in the treatment of viral diseases. We are advancing novel investigational oral small molecule antiviral agents that have potent activity against difficult to treat or resistant virus strains that threaten human health: COVID-19/Long COVID and bird flu and seasonal influenza. Ratutrelvir is in development as a ritonavir-independent COVID treatment, targeting the Main protease (Mpro or 3CL protease). Tivoxavir marboxil is in development as a single dose treatment for bird flu and seasonal influenza, targeting the influenza cap-dependent endonuclease (CEN). Traws is actively seeking development and commercialization partners for its legacy clinical oncology programs, rigosertib and narazaciclib. More details can be found on Traws’ website at . For more information, please visit and follow us on LinkedIn. Forward-Looking Statements Some of the statements in this release are forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, Section 21E of the Securities Exchange Act of 1934, as amended, and the Private Securities Litigation Reform Act of 1995, and involve risks and uncertainties including statements regarding the Company, its business and product candidates, including the potential opportunity, market size, benefits, effectiveness, safety, and the clinical and regulatory plans for ratutrelvir and tivoxavir marboxil, as well as plans for its legacy programs. The Company has attempted to identify forward-looking statements by terminology including “believes”, “estimates”, “anticipates”, “expects”, “plans”, “intends”, “may”, “could”, “might”, “will”, “should”, “preliminary”, “encouraging”, “approximately” or other words that convey uncertainty of future events or outcomes. Although Traws believes that the expectations reflected in such forward-looking statements are reasonable as of the date made, expectations may prove to have been materially different from the results expressed or implied by such forward looking statements. These statements are only predictions and involve known and unknown risks, uncertainties, and other factors, including the outcome of Traws’ IND filing with the FDA, including the current FDA clinical hold for tivoxavir marboxil; the success and timing of Traws’ clinical trials; the potential efficacy of ratutrelvir for the treatment of COVID-19, including the potential to reduce the risk of COVID rebound and Long COVID; the potential for ratutrelvir to gain market acceptance, if and when regulatory approval is obtained, or to become the new standard of care; Traws’ interactions with the FDA, BARDA and similar foreign regulators; collaborations; market conditions; regulatory requirements and pathways for approval; the ongoing need for improved therapy to reduce the frequency of clinical rebound and the concomitant risk for Long COVID; the extent of the spread and threat of the bird flu; the Company’s cash projections; Traws’ ability to raise additional capital when needed; and those discussed under the heading “Risk Factors” in Traws’ filings with the U.S. Securities and Exchange Commission (SEC). Any forward-looking statements contained in this release speak only as of its date. Traws undertakes no obligation to update any forward-looking statements contained in this release to reflect events or circumstances occurring after its date or to reflect the occurrence of unanticipated events, except to the extent required by law. Traws Pharma Contact: Charles Parker Traws Pharma, Inc. cparker@trawspharma.com Investor Contact: John Fraunces LifeSci Advisors, LLC 917-355-2395 jfraunces@lifesciadvisors.com

Clinical ResultPhase 1Phase 2

03 Feb 2026

·www.pharmaceutical-technology.com

Pfizer sets sights on R&D strategy amid modest FY25 results

Pfizer and investors alike look forward to further developments within the pharma’s newly acquired obesity portfolio. Image credit: ShU studio via ShutterStock.com. New York-based pharma giant Pfizer has met targets for its fiscal year 2025 (FY25) financials, which come as the company looks to refresh its portfolio amid looming patent losses and waning Covid vaccine sales. In FY25, Pfizer generated full-year revenues of $62.6bn. While this meets the company’s previously adjusted FY25 profit forecast of $62bn , it represents a 2% operational decline compared to FY24. Earnings per share (EPS) were in line with Citi analyst consensus, standing at $1.36, although they were lower than the 2024 rate of $1.41. The company also reaffirmed its 2026 financial guidance, with revenues between $59.5bn and $62.5bn expected, with a diluted EPS range of $2.80 to $3.00. The results follow a tough 2025 for Pfizer, in which the company has battled with declining Covid-19 vaccine sales and the upcoming loss of exclusivity impacting several key drugs in its portfolio, including Janus kinase (JAK) inhibitor, Xeljanz (tofacitinib). Currently, Pfizer forecasts that patent expiries will result in $1.5bn of revenue losses in FY26. Despite this overall loss, 2025 revenues were looking more favourable when Covid-19 vaccines Paxlovid (nirmatrelvir/ritonavir) and Comirnaty (Covid-19 vaccine, mRNA) were discounted from the equation – with the rest of the company’s pipeline achieving operational growth of 6%. Within its wider primary care portfolio, Pfizer’s respiratory syncytial virus (RSV) vaccine, Abrysvo was a strong driver of growth, bringing in $1bn across the global market – up 37% from the $755m in total sales achieved in FY24. This offset the 9% total revenue decline observed in the US, which comes amid the Trump administration’s continued efforts to alter vaccine policy . Sanofi’s RSV jab, Beyfortus (nirsevimab), experienced a similar, but steeper decline in US sales during FY2025 . GlobalData Strategic Intelligence US Tariffs are shifting - will you react or anticipate? Don’t let policy changes catch you off guard. Stay proactive with real-time data and expert analysis. By GlobalData Learn more about Strategic Intelligence Pfizer and Bristol Myers Squibb’s (BMS) best-selling blood thinner, Eliquis (apixaban), also had a good year, posting an 8% sales increase compared to 2024, with $7.96bn in total sales for 2025. However, this may be one of the last years of consistent growth for the factor Xa blocker, as its key patents are set to expire between 2027 and 2029. Within its oncology portfolio, Pfizer touted positive financial results from its antibody-drug conjugate (ADC) Padcev (enfortumab vedotin), which made 22% more than 2024 by generating global sales of $1.94bn. It was a similar story for anaplastic lymphoma kinase (ALK) inhibitor Lorbrena (lorlatinib), which hit blockbuster status while demonstrating YoY growth of 40%. Despite these wins, investors do not appear to be best pleased with Pfizer’s overall FY25 sales outcome, as the pharma’s stock value dropped by 4.9% from $26.66 at market close on 2 February to $25.36 at market open on 3 February after the results debuted. The New York-based pharma has a market cap of $144.4bn. Pfizer focuses on R&D to foster future growth In an investor call held on 3 February, Pfizer’s CEO, Albert Bourla, touted 2026 as a “key catalyst” for the company’s future growth up to 2030, noting that the initiation of 20 key pivotal studies will help “maximise opportunities” for the company. At the recent 2026 J.P. Morgan Healthcare Conference in San Francisco, Bourla shared Pfizer’s plans to deliver a “catalyst-rich R&D agenda,” while maximising the value of its recent transactions – including its $10bn buyout of obesity biotech, Metsera . This deal already appears to be reaping benefits for Pfizer, as its newly acquired, once-monthly glucagon-like peptide 1 receptor agonist (GLP-1RA), PF3994, met its primary trial endpoint of significant weight reduction at 28 weeks during the Phase IIb VESPER-3 study (NCT06973720). The therapy, which was previously known as MET-097i, is now expected to enter 10 Phase III trials in 2026 across the obesity space. In a research note, Citi analysts noted that they were most compelled by the successful transition to a monthly dosing schedule, as well as the continued weight loss trajectory with no observed plateau, which they say could “reinforce confidence in the asset’s potential”. To help fund studies on its clinical pipeline, Bourla noted that Pfizer has been, and will continue to create cost savings within R&D and across the wider business through the deployment of artificial intelligence (AI). Adding to Bourla’s point, Chris Boshoff, CSO and president of R&D, says the company is “recruiting and embedding AI engineers” across discovery, medical regulatory, safety, pharmacovigilance and clinical trial execution to “measure success, productivity, speed and costs”.

Clinical ResultPhase 2VaccineAcquisitionPhase 1

26 Jan 2026

·www.globenewswire.com

Traws Pharma Completes Enrollment of Ratutrelvir Clinical Study in PAXLOVID®-Eligible and Ineligible COVID-19 Patients; Announces Plans for Added Indication for Tivoxavir Marboxil as a Prophylactic Treatment for Seasonal Influenza

Ongoing clinical results with ratutrelvir confirm a differentiated profile versus PAXLOVID® with fewer adverse events, no viral rebounds to date and faster time to sustained symptom resolution; results recapitulated in PAXLOVID®-ineligible patients, representing a significant population with few effective treatment options Compressed tablets of tivoxavir marboxil predicted to provide 28-day protection from influenza against wide range of seasonal and pandemic-potential variants Human influenza prophylaxis challenge study time slot secured for June 2026 NEWTOWN, Pa., Jan. 26, 2026 (GLOBE NEWSWIRE) -- Traws Pharma, Inc. (NASDAQ: TRAW) (“Traws Pharma”, “Traws” or “the Company”), a clinical-stage biopharmaceutical company developing novel therapies to target critical threats to human health from respiratory viral diseases, today announced the completion of enrollment in its ongoing 90-patient, open-label Phase 2 study of ratutrelvir, an investigational oral, ritonavir-free Mpro/3CL protease inhibitor, versus PAXLOVID®, in patients with mild-to-moderate COVID-19, together with a single arm in PAXLOVID®-ineligible subjects. Patients ineligible to receive PAXLOVID® are frequently at elevated risk for severe disease and require suitable, safe and effective treatment options. Ratutrelvir has the potential to address this gap in care and may be a valuable therapeutic option. The Company also provided an update on the progress of the tivoxavir marboxil program for influenza. Ratutrelvir Update The study, designed as an active-controlled comparator trial versus PAXLOVID® (nirmatrelvir/ritonavir), evaluated patient-reported symptom outcomes, safety, and real-world usability. A separate treatment arm was comprised of patients ineligible for ritonavir-boosted regimens due to contraindications or clinically significant drug–drug interactions. Patients in the ratutrelvir arm received ratutrelvir 600 mg orally, once daily for 10 days, while patients in the comparator arm received oral PAXLOVID®, administered as nirmatrelvir 300 mg twice daily plus 100 mg ritonavir twice daily for 5 days, consistent with approved prescribing information. “From a clinical perspective, the ongoing data analysis confirms previous reports that ratutrelvir may provide a meaningful benefit across a broader range of patients, including those who are unable to receive ritonavir-boosted therapy,” commented Robert R. Redfield, MD, Chief Medical Officer of Traws Pharma. “The favorable tolerability profile, together with a shortened time to symptom resolution and the absence of viral rebound events in ratutrelvir-treated patients, encourages and supports the continued clinical evaluation of ratutrelvir in both acute COVID-19 and in studies designed to better understand its potential impact on longer-term outcomes.” “The combination of early and sustained symptom improvement, extended dosing duration, absence of viral rebound observed to date, and favorable tolerability supports the strategic hypothesis that ratutrelvir may have utility in reducing post-acute sequelae of SARS-CoV-2 infection (Long COVID),” continued Dr. Redfield. “By enabling earlier and potentially more complete viral clearance, without the limitations associated with ritonavir boosting, ratutrelvir may offer a differentiated approach to both acute COVID-19 treatment and prevention of longer-term complications.” Tivoxavir Marboxil Update The Company additionally announced that it is progressing an additional indication for tivoxavir marboxil (TXM), a potential best in class CAP-dependent endonuclease inhibitor, as a single monthly oral tablet for the prophylactic treatment of seasonal influenza. “In prior Phase 1 studies in healthy volunteers, an unformulated powder-in-capsule formulation provided blood levels exceeding 3X the EC50 against a basket of common seasonal influenza variants for up to 22 days after drug administration. A new compressed tablet formulation may provide 28 day coverage, enabling a once-a-month prophylactic treatment,” commented C. David Pauza, PhD, Chief Science Officer of Traws Pharma. “Once a planned bridging healthy volunteer study has confirmed the extended exposure, we will progress TXM into a seasonal influenza virus prophylaxis Challenge Study in June 2026 at hVIVO, the pre-eminent CRO for such studies. Positive results will enable progression into registration studies,” continued Dr. Pauza. “Collectively, the advancement of our antiviral portfolio provides a number of significant value inflection points and could provide needed treatment and prevention options for clinically important viral diseases,” commented Iain Dukes, MA, DPhil, Chief Executive Officer of Traws Pharma. About Ratutrelvir Ratutrelvir is an investigational oral, small molecule Mpro (3CL protease) inhibitor designed to be a broadly acting treatment for SARS-CoV-2/COVID-19 that is used without ritonavir. It has demonstrated in vitro activity against a range of virus strains. Preclinical and Phase 1 studies show that ratutrelvir does not require co-administration with a metabolic inhibitor, such as ritonavir, which could avoid ritonavir-associated drug-drug interactions1, and potentially enable wider patient use. Phase 1 data also show that ratutrelvir’s pharmacokinetic (PK) profile demonstrated maintenance of target blood plasma levels approximately 13 times above the EC50 using the target Phase 2 dosing regimen of 600 mg/day for ten days, which may also reduce the likelihood of clinical rebound and, consequently, reduce the risk for Long COVID2. Industry data indicate that COVID treatment represents a potential multi-billion dollar market opportunity3. About Tivoxavir Marboxil Tivoxavir marboxil (TXM) is an investigational oral, small molecule CAP-dependent endonuclease inhibitor designed to be administered as a single-dose for the treatment of bird flu and the treatment or prophylaxis of seasonal influenza. It has shown potent in vitro activity against a range of influenza strains in preclinical studies, including a human isolate of the highly pathogenic avian flu H5N1 (bird flu). Consistent, positive preclinical data from three animal species indicate that a single dose of TXM demonstrated a therapeutic effect against H5N1 bird flu. Seasonal influenza represents an estimated multi-billion dollar antiviral market opportunity, largely driven by global health organizations, practice guidelines and government tenders and inclusion in drug stock piling initiatives4,5, with upside potential from potential pandemic flu outbreaks including H5N1 bird flu. We believe that these data support further development of TXM as a treatment for bird flu. Source information https://ascpt.onlinelibrary.wiley.com/doi/pdf/10.1002/cpt.2646Carly Herbert et al. (2025) Clinical Infectious Diseases. https://pubmed.ncbi.nlm.nih.gov/39692474/Pfizer Inc. annual report on Form 10-K for the fiscal year ended December 31, 2024, filed with the U.S. Securities and Exchange Commission on February 27, 2025Per link TRAW data on file Third-party products mentioned herein are the trademarks of their respective owners. About Traws Pharma, Inc. Traws Pharma is a clinical stage biopharmaceutical company dedicated to developing novel therapies to target critical threats to human health in respiratory viral diseases. Traws integrates antiviral drug development, medical intelligence and regulatory strategy to meet real world challenges in the treatment of viral diseases. We are advancing novel investigational oral small molecule antiviral agents that have potent activity against difficult to treat or resistant virus strains that threaten human health: COVID-19/Long COVID and bird flu and seasonal influenza. Ratutrelvir is in development as a ritonavir-independent COVID-19 treatment, targeting the Main protease (Mpro or 3CL protease). Tivoxavir marboxil is in development as a single dose treatment for bird flu and seasonal influenza, targeting the influenza cap-dependent endonuclease (CEN). Traws is actively seeking development and commercialization partners for its legacy clinical oncology programs, rigosertib and narazaciclib. More details can be found on Traws’ website at https://www.ir.trawspharma.com/partnering. For more information, please visit www.trawspharma.com and follow us on LinkedIn. Forward-Looking Statements Some of the statements in this release are forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, Section 21E of the Securities Exchange Act of 1934, as amended, and the Private Securities Litigation Reform Act of 1995, and involve risks and uncertainties including statements regarding the Company, its business and product candidates, including the potential opportunity, market size, benefits, effectiveness, safety, and the clinical and regulatory plans for ratutrelvir and tivoxavir marboxil, as well as plans for its legacy programs. The Company has attempted to identify forward-looking statements by terminology including “believes”, “estimates”, “anticipates”, “expects”, “plans”, “intends”, “may”, “could”, “might”, “will”, “should”, “preliminary”, “encouraging”, “approximately” or other words that convey uncertainty of future events or outcomes. Although Traws believes that the expectations reflected in such forward-looking statements are reasonable as of the date made, expectations may prove to have been materially different from the results expressed or implied by such forward looking statements. These statements are only predictions and involve known and unknown risks, uncertainties, and other factors, including the outcome of Traws’ IND filing with the FDA; the potential efficacy and tolerability of ratutrelvir for the treatment of COVID-19, including the potential to reduce the risk of COVID rebound and Long COVID; the success and timing of Traws’ clinical trials, including when Traws will report results of its studies of tivoxavir marboxil; the potential efficacy of tivoxavir marboxil to provide 28-day coverage against seasonal influenza variants; the potential for ratutrelvir or tivoxavir marboxil to gain market acceptance, if and when regulatory approval is obtained, or to become the new standard of care; Traws’ interactions with the FDA, BARDA and similar foreign regulators; collaborations; market conditions; regulatory requirements and pathways for approval; the ongoing need for improved therapy to reduce the frequency of clinical rebound and the concomitant risk for Long COVID; the extent of the spread and threat of the bird flu; the Company’s cash projections; Traws’ ability to raise additional capital when needed; and those discussed under the heading “Risk Factors” in Traws’ filings with the U.S. Securities and Exchange Commission (SEC). Any forward-looking statements contained in this release speak only as of its date. Traws undertakes no obligation to update any forward-looking statements contained in this release to reflect events or circumstances occurring after its date or to reflect the occurrence of unanticipated events, except to the extent required by law. Traws Pharma Contact: Charles ParkerTraws Pharma, Inc.cparker@trawspharma.com www.trawspharma.com Investor Contact: John Fraunces LifeSci Advisors, LLC917-355-2395jfraunces@lifesciadvisors.com

Clinical ResultPhase 1Phase 2

100 Deals associated with Nirmatrelvir

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KEGG	Wiki	ATC	Drug Bank
-	Nirmatrelvir	-	-

R&D Status

10 top R&D records.

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Indication	Highest Phase	Country/Location	Organization	Date
COVID-19	Phase 3	Brazil	Pfizer Inc.	16 Jul 2021
COVID-19	Phase 3	Czechia	Pfizer Inc.	16 Jul 2021
COVID-19	Phase 3	Hungary	Pfizer Inc.	16 Jul 2021
COVID-19	Phase 3	Russia	Pfizer Inc.	16 Jul 2021
COVID-19	Phase 3	South Korea	Pfizer Inc.	16 Jul 2021
COVID-19	Phase 3	Spain	Pfizer Inc.	16 Jul 2021
Common Cold	Phase 2	Sweden	Pfizer Inc.	30 Mar 2023
Dyspnea	Phase 2	Sweden	Pfizer Inc.	30 Mar 2023
Post Acute COVID 19 Syndrome	Phase 2	Sweden	Pfizer Inc.	30 Mar 2023
Liver Injury	Phase 1	United States	Pfizer Inc.	31 Aug 2021

Clinical Result

Indication

Phase

Evaluation

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Study	Phase	Population	Analyzed Enrollment	Group	Results	Evaluation	Publication Date


NCT05263895 (CTgov)	Phase 1	-	12	Nirmatrelvir+Ritonavir (Nirmatrelvir (Commercial Tablets)/Ritonavir 300/100 mg)	kpnaadqiss(bhydpmosov) = xutxnggevb ibyiwifblb (etkcgmabmv, 15) View more	-	11 Jun 2025
				Nirmatrelvir+Ritonavir (Nirmatrelvir (Slower Dissolution Tablets)/Ritonavir 300/100 mg)	kpnaadqiss(bhydpmosov) = fpdxfotdpk ibyiwifblb (etkcgmabmv, 26) View more
NCT05041907 (Pubmed \| Int J Anal Chem)	Phase 2	COVID-19	1	Nirmatrelvir	oruliieuag(bzsrqhbzyf) = fmuvycrntb hrhxnhbtua (exgijniszn )	Positive	01 Jan 2025
NCT05567952 (CTgov)	Phase 2	COVID-19	436	Nirmatrelvir+Ritonavir (Nirmatrelvir 300 mg + Ritonavir 100 mg)	bdlwmqxysb(aqlgheklmk) = szqwwtoxax pacjcbabui (hircaektbc, 0.129) View more	-	08 Oct 2024
				Placebo+Ritonavir (Placebo + Ritonavir 100 mg)	bdlwmqxysb(aqlgheklmk) = ulkvvmifwm pacjcbabui (hircaektbc, 0.171) View more
NCT05576662 (STOP-PASC, CTgov)	Phase 2	Post Acute COVID 19 Syndrome	168	Nirmatrelvir+Ritonavir (Nirmatrelvir Plus Ritonavir)	boadtadmnw = tvapfthwjg jxxmimxixu (qedzukljhb, cyykkwaexg - hvqbsgekil) View more	-	25 Sep 2024
				Placebo+Ritonavir (Placebo Plus Ritonavir)	boadtadmnw = bctdggtoom jxxmimxixu (qedzukljhb, awkvkceoma - ulnycmgmze) View more
NCT05438602 (EPIC-IC, CTgov)	Phase 2	COVID-19	158	Placebo+Nirmatrelvir+Ritonavir (Nirmatrelvir + Ritonavir 5 Day Then Placebo 10 Day)	ihvaueptae = inoaecjyaj tpedqxtlkt (lfymhmswsf, wyibhxmogf - xamizmwcoi) View more	-	23 Sep 2024
				Placebo+Nirmatrelvir+Ritonavir (Nirmatrelvir + Ritonavir 10 Day Then Placebo 5 Day)	ihvaueptae = jlixcfqeov tpedqxtlkt (lfymhmswsf, ufdjqzwaqp - zfnsuhjnkb) View more
NCT05487040 (CTgov)	Phase 1	COVID-19	15	PF-07321332 (nirmatrelvir)+ritonavir (Cohort 1 (No HD))	iiavfqlaud = tddfbszqbs gvrnasgodo (nuythzpdgb, ebgqyygfij - xmurgaixll) View more	-	23 Sep 2024
				PF-07321332 (nirmatrelvir)+ritonavir (Cohort 2 (Intermittent HD))	iiavfqlaud = wgifhmhdij gvrnasgodo (nuythzpdgb, wnqnsfeaoi - xmmgxxfmgd) View more
NCT05011513 (EPIC-SR, Pubmed) Manual	Phase 2/3	COVID-19	1,288	Nirmatrelvir-riritonavir	rmnuxjbkni(jqbwoaytmr) = yyiyyahsph cqcznezgde (udxzsxvjwl ) View more	Negative	04 Apr 2024
				Placebo	rmnuxjbkni(jqbwoaytmr) = srosuowcqz cqcznezgde (udxzsxvjwl ) View more
NCT05005312 (CTgov)	Phase 1	Liver Injury	17	PF-07321332+ritonavir (Normal Hepatic Function)	yjkgudxxcf(gqiinmtijm) = aavzayrmmp qghdtnnwxz (nruxwixyyo, 20) View more	-	06 Sep 2023
				PF-07321332+ritonavir (Moderate Hepatic Impairment)	yjkgudxxcf(gqiinmtijm) = nynrjnbmrr qghdtnnwxz (nruxwixyyo, 48) View more
NCT05011513 (EPIC-SR, CTgov)	Phase 2/3	COVID-19	1,440	Placebo	rmevwqcbdo(lnrakzaoak) = yupaeusbcv ayafkktzpn (faylmgower, ficwsmrism - krkqdhnwcr) View more	-	14 Aug 2023
NCT05047601 (CTgov)	Phase 2/3	COVID-19	2,954	Placebo for PF-07321332	frhhzxlzat = cvajbgzmrv oathjkzcea (emxccfdfsi, sescmfxhdr - dveqxoubdi) View more	-	06 May 2023

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