Traws Pharma’s COVID-19 Candidate, Ratutrelvir, Presented at ICAR

Rhea-AI Summary

Traws Pharma (NASDAQ: TRAW) presented positive data for its COVID-19 treatment candidate ratutrelvir at ICAR 2025 in Las Vegas. The drug, designed as a main protease inhibitor, shows promising advantages over current treatments:

Key findings from preclinical and Phase 1 data indicate that ratutrelvir:

• Can be used without ritonavir (a boosting agent), reducing drug interaction risks
• Effectively suppresses 18 different SARS-CoV-2 strains, including nirmatrelvir-resistant and Omicron variants
• Maintains blood levels within therapeutic window at 600 mg/day for 10 days
• Shows excellent safety and tolerability in Phase 1 trials
• Maintains drug levels above EC90 for 2 days after treatment ends

The company is preparing for FDA interactions and Phase 2 studies, with an upcoming Investor Event scheduled for March 31, 2025.

Positive

• Drug shows efficacy without ritonavir co-administration, reducing complexity and drug interaction risks
• Demonstrates activity against 18 SARS-CoV-2 strains including resistant variants
• Excellent safety and tolerability profile in Phase 1 trials
• Maintains therapeutic levels for extended period (2 days post-treatment)
• Phase 1 data supports advancement to Phase 2 trials

Negative

• Still in early clinical development phase (Phase 1)
• FDA approval pathway not yet established
• Faces competition from existing approved COVID-19 treatments

Insights

Biotech Development Analyst

Traws Pharma's COVID-19 candidate ratutrelvir represents a potentially significant advancement in COVID-19 treatment based on the Phase 1 results and preclinical data presented at ICAR 2025. The most compelling aspect is ratutrelvir's differentiated profile - particularly that it doesn't require ritonavir co-administration, a key limitation of current treatments that introduces drug-drug interaction concerns.

The Phase 1 data demonstrates important pharmacokinetic advantages with the 600mg/day dose maintaining blood levels at 4x the EC90 throughout the 10-day regimen, and remaining above therapeutic levels for two days post-treatment. This extended coverage could potentially address two critical clinical challenges: viral rebound and long COVID risk.

From a competitive standpoint, ratutrelvir's activity against nirmatrelvir-resistant strains and distinct resistance mutation profile positions it favorably against Paxlovid and ensitrelvir. The preclinical efficacy against 18 SARS-CoV-2 strains, including Omicron variants, suggests broad applicability.

While these early results are promising, investors should note this remains an early-stage asset preparing for Phase 2. The path to potential approval will require larger studies demonstrating efficacy in infected patients. The upcoming FDA interaction will be crucial in determining trial design requirements and timeline to market. The scheduled investor event on March 31 should provide additional insight into the development roadmap.

• Preclinical and Phase 1 data suggest that ratutrelvir can be used without ritonavir and may reduce the likelihood of COVID rebound and the risk of long COVID due to a longer treatment regimen
• Preparations are underway for FDA interactions and initiation of Phase 2 studies
• Data presentation to be provided at the Investor Event on March 31, 2025 at 10:00 AM ET

NEWTOWN, Pa., March 25, 2025 (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 that positive data supporting the potential for ratutrelvir, a main protease inhibitor, as a treatment for COVID-19, were presented on March 20, 2025 in a poster at the International Conference for Antiviral Research (ICAR 2025), held in Las Vegas, Nevada.

Robert R. Redfield, MD, Chief Medical Officer for Traws Pharma and former Director of the U.S. Centers for Disease Control and Prevention (CDC), commented, “Traws designed ratutrelvir to overcome the limitations of current COVID treatments. COVID continues to be a significant cause of mortality for older adults with underlying medical conditions and people who are immunocompromised¹. Requirement to use the boosting agent ritonavir with widely used treatment² increases drug-drug interaction risk for patients with complex medical conditions and may limit patient eligibility for therapy³. Data presented at ICAR provide support that ratutrelvir treatment does not require co-administration of a metabolism inhibitor such as ritonavir, significantly simplifying ease of use, a key potential differentiator.”

C. David Pauza, PhD, Chief Science Officer for Traws Pharma, added: “Recent publications cite a relationship between the probability of slow viral clearance being associated with higher risk for long COVID⁴. Ratutrelvir suppressed replication of 18 different strains of SARS-CoV-2 in laboratory tests, maintained human blood levels within the predicted therapeutic window (>EC₉₀), and did not require coadministration of ritonavir. Data presented at ICAR 2025 shows that ratutrelvir is highly active against native virus and nirmatrelvir-resistant strains and omicron variants. Additionally, we know that the patterns of drug resistance mutations selected in vitro using ratutrelvir are largely distinct from the emerging clinical data on drug resistance to nirmatrelvir (protease inhibitor in Paxlovid™)⁴ and ensitrelvir⁵. Ratutrelvir is differentiated from these drugs in terms of in vitro potency, human pharmacokinetics, and drug resistance patterns.”

“We believe ratutrelvir has the potential to be a highly differentiated, broadly active treatment for COVID. Preparations are underway to meet with the FDA to align on a path forward and initiate Phase 2 studies,” noted Werner Cautreels, PhD, Chief Executive Officer for Traws Pharma. “We plan to host an Investor Event on Monday, March 31, 2025 at 10:00 AM ET to present an overview of preclinical and human data on ratutrelvir and outline potential next steps towards approval.”

To register for the virtual Investor Event, click here.

Ratutrelvir poster:

Poster Title:	Phase I Clinical Study of Ratutrelvir, a Potent Inhibitor of the SARS-CoV-2 Main Protease (Mpro/3CL): Safety, Tolerability, Pharmacokinetics and Pharmacodynamics
Poster Date:	March 20, 2025

Data in the poster suggest that ratutrelvir could be used for COVID-19 therapy without ritonavir. Phase 1 results helped Traws define a target Phase 2 dose and treatment regimen and demonstrated excellent overall safety and tolerability:

• Potent Preclinical Suppression of Resistant Virus: Laboratory studies show that ratutrelvir is a highly active suppressor of COVID-19 replication of original and Omicron variants
• Pharmacokinetic (PK) Results Do Not Require a Metabolism Inhibitor: Drug exposure studies show that ratutrelvir metabolism is not induced by ten days of treatment at 600 mg/day and trough blood plasma levels of drug are maintained at four times the EC₉₀. These data provide support that ratutrelvir treatment does not require coadministration of a metabolism inhibitor such as ritonavir, significantly simplifying ease of use, a key differentiator
• Phase 1 data also show potential safety and attractive PK for a 10-day regimen: Data from single- and multiple ascending dose (SAD, MAD) studies demonstrated excellent safety/tolerability at all doses tests
  

At the selected Phase 2 dose and regimen of 600 mg/day for 10 days, ratutrelvir established and maintained 24-hour trough blood levels of approximately 13-times the EC₅₀ and drug levels remained above the EC₉₀ for 2 days after treatments cessation. The 10-day dosing regimen is intended to achieve optimal viral suppression and reduce the rates for clinical rebound

About Ratutrelvir
Ratutrelvir is an investigational oral, small molecule Mpro (3CL protease) inhibitor designed to be a broadly acting treatment for COVID-19, to be used without ritonavir. It has demonstrated in vitro activity against a range of COVID-19 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 interactions³, 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 COVID.⁴ Industry data indicate that COVID treatment represents a potential multi-billion dollar market opportunity^7,8.

Source information:

1. https://www.cdc.gov/covid/risk-factors/index.html
2. https://s28.q4cdn.com/781576035/files/doc_financials/2024/q4/Q4-2024-PFE-Earnings-Release-Final.pdf
3. https://ascpt.onlinelibrary.wiley.com/doi/pdf/10.1002/cpt.2646
4. Carly Herbert et al. (2025) Clinical Infectious Diseases. https://doi.org/10.1093/cid/ciae539
5. Tamura, T.J, et al., 2024, JAMA Network Open 7:e2435431-e2435431
6. Uehara, T., H.et al., (2025). "Ensitrelvir treatment–emergent amino acid substitutions in SARS-CoV-2 3CLpro detected in the SCORPIO-SR phase 3 trial." Antiviral Research 236: 106097
7. Pfizer.com 10K report 2024, Feb 27, 2025 ;
8. Merck.& Co 10K, Feb 25 2025

Paxlovid is a registered trademark of Pfizer Inc.

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. We are advancing novel investigational antiviral agents that have potent activity against difficult to treat or resistant virus strains that threaten human health. Our product candidates are intended to be safe, with simple dosing regimens. We strive to utilize accelerated clinical trial strategies with a commitment to patients who are especially vulnerable.

The Company’s two antiviral programs are investigational oral small molecules targeting bird flu and seasonal influenza, and COVID-19. Tivoxavir marboxil is in development as a single dose treatment for bird flu and seasonal influenza, targeting the influenza cap-dependent endonuclease (CEN). Ratutrelvir is in development as a COVID treatment, targeting the Main protease (Mpro or 3CL protease), without the need for co-administration of ritonavir.

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, benefits, effectiveness, safety, and the clinical and regulatory plans for tivoxavir marboxil and ratutrelvir. 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 success and timing of Traws’ clinical trials, Traws’ interactions with and guidance from the FDA, 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, 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:
Nora Brennan
Traws Pharma, Inc.
nbrennan@trawspharma.com
www.trawspharma.com

Investor Contact:
Bruce Mackle
LifeSci Advisors, LLC
646-889-1200
bmackle@lifesciadvisors.com   

FAQ

What are the key advantages of TRAW's ratutrelvir over existing COVID-19 treatments?

Ratutrelvir can be used without ritonavir, reducing drug interaction risks, and shows activity against 18 SARS-CoV-2 strains, including resistant variants. It maintains therapeutic levels for a 10-day treatment regimen.

What were the Phase 1 trial results for TRAW's ratutrelvir?

Phase 1 trials showed excellent safety and tolerability at all doses, with 600 mg/day maintaining blood levels 13-times the EC50 and above EC90 for 2 days post-treatment.

When will TRAW begin Phase 2 trials for ratutrelvir?

Traws Pharma is preparing for FDA interactions to align on the path forward and initiate Phase 2 studies, with more details to be presented at their March 31, 2025 Investor Event.

How does TRAW's ratutrelvir perform against COVID-19 variants?

Ratutrelvir effectively suppresses multiple COVID-19 strains, including original virus, nirmatrelvir-resistant strains, and Omicron variants, with distinct resistance patterns from existing treatments.