BlueSky Immunotherapies Advances Intracervical HPV16 Immunotherapy into Final Cohort Following Positive Interim Safety Review

Vienna, September 2026 – Higher 9.0 log10 fTCID50 Dose Demonstrated Safety and Tolerability, with Early Signs of HPV Clearance

BlueSky Immunotherapies today announced encouraging interim results from its ongoing BS-02 Phase 1 clinical trial evaluating the company’s proprietary delNS viral vector FluBHPVE6E7 for the treatment of persistent HPV16 infection and associated cervical lesions.

Following successful completion of the first two dose-escalation cohorts, the independent Data Monitoring Committee (DMC) has reviewed the accumulated clinical and laboratory safety data and approved progression to the third and final cohort of the Phase 1 safety study.

Importantly, after the first cohort established the safety and tolerability of the lower dose, the second cohort evaluated the higher 9.0 log10 fTCID50 per dose. Following its review of the second cohort, the DMC concluded that the higher dose was also safe and well tolerated, allowing the study to proceed to its final cohort at the highest planned dose level.

In addition to the favorable safety findings, early indications of biological activity were observed at the higher dose, including clearance of HPV16 infection in treated participants. HPV16 is the causative viral infection underlying the cervical lesions being evaluated in the study. These preliminary observations are particularly encouraging given that the BS-02 study is designed to investigate whether local intracervical administration can directly target persistent HPV infection and associated cervical abnormalities.

The BS-02 study represents an important evolution of BlueSky’s clinical development strategy. In the company’s previously completed Phase 1 cervical trial, FluBHPVE6E7 was administered systemically by subcutaneous, intradermal or intramuscular routes. That study demonstrated a favorable safety profile and encouraging clinical activity, including HPV16 clearance and regression of cervical lesions, with particularly strong responses observed following subcutaneous administration.

In BS-02, BlueSky is evaluating a fundamentally different approach: initial local administration directly into the cervix, followed by two intramuscular administrations at weeks 4 and 12. The study is designed to investigate whether delivering the delNS vector directly to the site of persistent HPV infection can enhance the local immune response while maintaining systemic immunization. The protocol includes women with confirmed persistent HPV16 infection and cervical cytology ranging from NILM and ASC-US through LSIL, CIN1 and CIN2, where a wait-and-see approach is appropriate.

“Our experience from the completed systemic Phase 1 study provided the clinical foundation for testing whether we could further improve the treatment concept by bringing the first administration directly to the site of HPV infection,” said Dr. Thomas Muster, Chief Executive Officer of BlueSky Immunotherapies. “We are therefore particularly encouraged that the higher 9.0 log dose has been confirmed by the independent DMC to be safe and well tolerated, while at the same time we are beginning to see signals of HPV clearance.”

“The elimination of the underlying HPV16 infection is an important component of our therapeutic strategy,” Dr. Muster continued. “Our objective is not simply to induce regression of a cervical lesion, but to generate an immune response capable of eliminating the persistent virus that drives the disease. The early observations from BS-02 provide encouraging support for this concept, although the study remains an exploratory Phase 1 trial and the findings will require confirmation in larger controlled studies.”

FluBHPVE6E7 is based on BlueSky’s proprietary delNS platform, in which the interferon-antagonist NS1 of an influenza B vector is partially deleted and replaced with the HPV16 tumor antigens E6 and E7. The resulting vector is designed to combine strong innate immune stimulation with targeted presentation of HPV antigens. The BS-02 protocol identifies induction of HPV-specific T-cell and cytokine responses, HPV16 clearance and changes in cervical cytology among its secondary objectives.
The study is a randomized, double-blind, placebo-controlled Phase 1 dose-escalation study. The first cohort evaluates 7.5 log10 fTCID50/dose, while the second cohort evaluates 9.0 log10 fTCID50/dose. Following completion of dose escalation, an additional expansion cohort is planned at the highest safe and tolerated dose to collect further safety data.

BlueSky will now proceed with the third and final cohort of the Phase 1 study and continue follow-up of treated participants to assess the durability of HPV16 clearance and changes in cervical cytology. The protocol provides for longer-term follow-up at 12, 18 and 24 months after the treatment period.

The emerging BS-02 data, together with the results from the completed systemic cervical study and the ongoing clinical development of FluBHPVE6E7 in HPV-positive oropharyngeal squamous cell carcinoma, provide an expanding clinical data set supporting the potential of the delNS platform as a therapeutic approach to HPV-driven disease.

About BlueSky Immunotherapies

BlueSky Immunotherapies is a clinical-stage biotechnology company developing next-generation immunotherapies based on its proprietary delNS viral vector platform. The platform combines targeted expression of disease-associated antigens with potent innate immune stimulation and is being developed for HPV-associated precancerous lesions and cancers.

Forward-Looking Statements

This press release may contain forward-looking statements subject to applicable European Union regulations and Austrian financial disclosure laws. These statements involve risks and uncertainties that could cause actual results to differ materially from those projected or anticipated. In particular, the preliminary observations described above are derived from an ongoing Phase 1 study and have not been established as confirmatory evidence of efficacy. BlueSky Immunotherapies assumes no obligation to update these statements except as required by law.