Antiva Biosciences Announces Positive Top-Line Results from Phase 1b/2 Study of ABI-2280 for Treatment of Cervical High-Risk Human Papillomavirus (hrHPV) Infection

Study Achieves Primary and all Secondary Endpoints Demonstrating Clinically Meaningful, Statistically Significant Improvements in hrHPV Negativity at Week 12 as Compared to Placebo

46% of Patients Treated with 3mg Cumulative Dose for Two Weeks Demonstrated Negativity for hrHPV at Week 12 as Compared to 16% for Placebo Group

ABI-2280 Efficacy was Durable, with 87% of Responders at Week 12 Maintaining hrHPV Negativity at Week 24 based on Interim Data

Treatment Shown to be Safe and Well Tolerated with Most Common Adverse Events Categorized as Mild or Moderate and Localized to Treatment Area

REDWOOD CITY, Calif., Aug. 27, 2025 /PRNewswire/ -- Antiva Biosciences, a biopharmaceutical company developing novel, topical therapeutics for the treatment of high-risk infections and pre-cancerous lesions caused by human papillomavirus (HPV) in women, today announced positive top-line results from the company's Phase 1b/2 clinical trial of ABI-2280, an investigational topical treatment for oncogenic (high-risk) cervical HPV (hrHPV) infection. The study achieved its primary endpoint with patients receiving ABI-2280 demonstrating statistically significant improvements in the rate of hrHPV negativity at Week 12 as compared with placebo. Additionally, the trial showed ABI-2280 treatment to be safe and well tolerated with the most commonly reported adverse events (AEs) categorized as mild and moderate and localized to the treatment area.

"Women with persistent high-risk HPV have an approximately one-in-five chance of their infection progressing to pre-cancer or worse over four-to-six years, yet they do not have any options to treat the infection in the hopes of halting disease progression before this occurs. This reality highlights the clinical importance of the data generated in this study of ABI-2280, which demonstrated a 30 percent improvement in hrHPV negativity as compared to placebo, combined with a favorable safety and tolerability profile," said Margaret Stanley, OBE, FMedSci, Hon FRCOG, FFPH, Professor Emeritus, University of Cambridge. "Equally encouraging is the durability of the efficacy demonstrated by ABI-2280, which provides optimism that the treatment has the potential to keep HPV undetectable for long periods of time."

Each year in the United States, it is estimated that over six million women become newly infected with cervical hrHPV. When cervical hrHPV infections persist, they can lead to precancerous changes in the cervix and, ultimately, cervical cancer. There are no approved therapeutic options for treatment of hrHPV infections. Instead, these patients are counseled to wait and see if their infection clears or progresses to higher grade disease. During this wait and see period, patients are also at risk of transmitting this oncogenic virus to sexual partners. Approximately 30 percent of women with hrHPV fail to clear the virus within 12 months. These patients are considered to have persistent cervical hrHPV infections.

The Phase 1b/2 trial is a randomized, double-blind, placebo-controlled study designed to evaluate the safety, tolerability and efficacy of ABI-2280 administered intravaginally in women diagnosed with persistent cervical hrHPV infection. The study dosed a total of 139 female patients ranging in age between 25 and 55 years old who have had a documented hrHPV infection for at least one year without evidence of precancerous lesions worse than low grade cervical intraepithelial neoplasia (CIN1). Part A of the trial evaluated multiple placebo-controlled sentinel cohorts enrolled sequentially to determine the safety, tolerability and preliminary efficacy of various dose levels of ABI-2280 in two-week and six-week dosing regimens. Following the completion of the sentinel cohorts, the top cumulative dose from each of the two-week and six-week dosing regimens was advanced into Part B expansion cohorts for further evaluation of efficacy.

Results from Part B of the study demonstrated that both ABI-2280 treatment regimens (1 mg dosed three times over two weeks for a cumulative dose of 3 mg; 1 mg dosed five times over six weeks for a cumulative dose of 5 mg) drove increased hrHPV negativity rates at Week 12 as compared to placebo. For the primary efficacy endpoint, 46% of patients in the more frequently dosed 3mg cohort achieved hrHPV negativity at Week 12 for all hrHPV genotypes present at baseline as compared to only 16% of placebo patients (p=0.0077). The 3mg cohort also achieved statistically significant improvements over placebo for both Week 12 secondary endpoints of complete hrHPV negativity at Week 12 and two or more consecutive hrHPV negative tests by Week 12. While 32% of patients in the less frequently dosed 5mg cohort also achieved hrHPV negativity at Week 12 for all genotypes present at baseline, this result did not achieve statistical significance compared with placebo.

Both ABI-2280 treatment cohorts demonstrated clear separation from placebo in hrHPV negativity at every observed timepoint in the study (Weeks 2, 4, 8 and 12). Notably, interim Week 24 data demonstrated durability of therapeutic activity for ABI-2280. Interim data for all patients in the study who have reached Week 24 showed 87% of patients who were hrHPV negative at Week 12 following ABI-2280 treatment maintained hrHPV negativity at Week 24.

ABI-2280 demonstrated favorable safety and tolerability across all dose levels and regimens in the study. Among patients treated with ABI-2280, the most frequently reported adverse events were deemed to be mild or moderate and were localized to the lower genitourinary tract, consistent with the site of topical administration.

"We are very pleased with the top-line data readout from this trial of ABI-2280 as we believe it provides strong support for moving into a Phase 2b trial in women with high-risk HPV infections," said Elaine Chien, MD, FACOG, chief medical officer of Antiva. "We are thrilled to achieve clinically meaningful and statistically significant hrHPV negativity with the most frequently administered dose which provides a roadmap for potentially achieving even greater efficacy with optimized dosing strategies in Phase 2b."

ABI-2280 is expected to have potent activity across all genotypes of HPV worldwide and works by blocking HPV replication and inducing apoptosis in HPV-infected cells. Antiva has leveraged its development expertise to formulate a vaginal insert of ABI-2280 that enables at home self-administration at diagnosis.

About HPV-Related Diseases and Cervical Cancer

Human Papilloma Virus (HPV) is so common that nearly all sexually active men and women are infected with the virus at some point in their lives. Many of these are transient infections that the body is capable of clearing, but this typically takes months to years. When HPV infections persist, they are known to drive the formation of malignancies, including cervical, anal, vulvar, penile, and head and neck cancers.

The prevalence of cervical high-risk HPV (hrHPV) infection is estimated to be 20% among U.S. females of reproductive age, or approximately 19 million women. Each year in the U.S., it is estimated that over 6 million women become newly infected with hrHPV. There are currently no treatment options for hrHPV and these patients are counseled to wait and see if their infection clears or progresses to higher grade disease. During this wait and see period, patients are also at risk of transmitting this oncogenic virus to sexual partners. Approximately 30 percent of women with hrHPV fail to clear the virus within 12 months. These patients are considered to have persistent hrHPV and have an estimated 20 percent chance of having their infection progress to pre-cancer or cancer over the following four-to-six years. Women diagnosed with hrHPV often experience significant stress due to the social stigma of a sexually transmitted infection and the association with cervical cancer. The lack of available treatments further contributes to increased anxiety and emotional distress.

The introduction of prophylactic vaccines for HPV was a major step forward in the fight against HPV-associated cancers by preventing infection by certain high-risk HPV subtypes. However, due to low adoption rates in major territories such as the US, EU, and Japan, coverage of only 50% of all known oncogenic HPV genotypes with the most broad-spectrum vaccines currently available, and limited access to the vaccines in developing countries, HPV infections and the disease states driven by such infections remain a major unmet clinical need.

Globally, cervical cancer is the fourth most common cancer in women and as such represents a major public health problem. According to the World Health Organization, an estimated 660,000 women were diagnosed with cervical cancer worldwide and approximately 350,000 women died from the disease in 2022.

About Antiva Biosciences
Antiva Biosciences, Inc. is a clinical-stage biopharmaceutical company developing novel, topical therapeutics for the treatment of cervical diseases caused by HPV infection. The company's drug candidate, ABI-2280, is being developed as a topical treatment for women with high-risk HPV infection and high-grade cervical intraepithelial neoplasia (HSIL, CIN 2,3).

For more information, please visit: www.antivabio.com.

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