5 confirmed partial responses (PRs) among 13 evaluable non-small cell lung cancer (NSCLC) patients (ORR 38%); 1 confirmed PR among 7 breast cancer patients

Favorable safety and PK profile, with encouraging activity, demonstrate a therapeutic window for JK06

Company proceeding with expansion cohorts in NSCLC and breast cancer

Salubris Biotherapeutics, Inc. (SalubrisBio), a clinical-stage biotechnology company dedicated to discovering and developing novel complex biologic therapeutics, today announced data from the dose escalation portion of the Phase 1/2 study of JK06, a 5T4-targeted antibody drug conjugate (ADC), in patients with unresectable locally advanced or metastatic cancer, including non-small cell lung cancer (NSCLC) and breast cancer, which is being presented at the European Society for Medical Oncology (ESMO) Congress.

Data presented at ESMO include 34 patients enrolled in Europe with advanced relapsed/refractory solid tumors who were treated with JK06, once every three weeks, across five dose levels (1.5-8.0 mg/kg) in dose escalation. Among the 34 patients, 29 were response-evaluable, all having failed standard of care therapy, and among whom 83% had received three or more prior lines of treatment and 59% had received four or more prior lines of therapy at the time of enrollment.

Key efficacy findings among the 29 response-evaluable patients include:

• 6 patients attained confirmed partial responses (PRs) (21%).
• Among 13 NSCLC patients, 5 attained confirmed PRs (ORR 38%), with the longest duration of response lasting 30 weeks.
• Among 7 response-evaluable breast cancer patients, 1 attained a confirmed PR with a duration of response lasting 18 weeks.
• PRs were observed at 3.0 mg/kg (1 NSCLC), 4.5 mg/kg (3 NSCLC and 1 breast cancer), and 6.0 mg/kg (1 NSCLC).

Treatment with JK06 has been generally well-tolerated with predominantly low grade (Grades 1 and 2), manageable toxicities, such as fatigue, alopecia, decreased appetite, dry eye and diarrhea. Among treatment-related adverse events (TRAEs) occurring in at least 5% of patients, only the following ≥ Grade 3 events were observed:

• At dose levels 1.5-3.0 mg/kg (n=12 patients), 1 patient with Grade 3 peripheral neuropathy.
• At dose level 4.5 mg/kg (n=15 patients), 1 patient with Grade 3 keratitis.
• At dose levels 6.0-8.0 mg/kg (n=7 patients), 1 patient with Grade 3 fatigue, 1 patient with Grade 3 ALT increase, and 1 patient with Grade 5 pneumonitis.
• Pharmacokinetic analysis demonstrated free monomethyl auristatin E (MMAE) levels that were favorable at dose levels up to 4.5 mg/kg.

“We are encouraged by the promising preliminary data demonstrating the combination of safety and efficacy of JK06 among heavily pre-treated metastatic solid tumors, including in NSCLC and breast cancer, supporting our belief that JK06 has the potential to be a first-in-class, differentiated therapy for patients with 5T4-expressing cancers,” said Sam Murphy, Chief Executive Officer of Salubris Biotherapeutics. “We look forward to advancing the study into dose expansion in tumor-specific cohorts for NSCLC and breast cancer, while continuing to explore activity in other solid tumors known to overexpress 5T4, as we aim to improve outcomes for these patients with advanced, aggressive disease and limited therapeutic options.”

The Phase 1/2 open-label, dose-escalation and expansion study (NCT06667960) to assess the safety, pharmacokinetics, and preliminary efficacy of JK06 is ongoing, and the cohort expansion phase, which is currently enrolling, will determine the recommended Phase 2 dose for further development.

Details of the ESMO presentation are as follows:

Title: A Phase 1/2 Study of JK06, a 5T4-Targeted Antibody Drug Conjugate (ADC), in Patients with Unresectable Locally Advanced or Metastatic Cancer

Presenter: Nuria Kotecki, M.D. at Institut Jules Bordet, Anderlecht, Belgium

Abstract #: 961P

Session: Developmental Therapeutics

Date/Time: Sunday, October 19, 2025 | 12:00 – 1:00 PM CEST

About JK06

JK06 is a first-in-class quadrivalent, biparatopic ADC that selectively targets 5T4 with a monomethyl auristatin E (MMAE) payload. 5T4 is an oncofetal protein that is overexpressed in a wide range of solid tumors, including NSCLC, breast, renal and genitourinary cancers, and is associated with more aggressive tumor progression and reduced survival. JK06 has demonstrated picomolar affinity for 5T4 and rapid internalization due to the biparatopic design. Together with stable, site-specific payload conjugation, JK06 has further demonstrated robust efficacy and a clean safety profile in non-clinical studies.

About SalubrisBio

SalubrisBio is a clinical-stage biotechnology company dedicated to discovering and developing complex biologics for cardiovascular disease and oncology. The Company is currently progressing multiple innovative and rationally designed first-in-class therapeutics through clinical development programs, including JK07, the potential first disease-modifying biologic for heart failure, and JK06, a quadrivalent, biparatopic ADC targeting 5T4 for the treatment of cancer. SalubrisBio is headquartered in Gaithersburg, Maryland. For more information about SalubrisBio, visit us at www.salubrisbio.com and connect with us on LinkedIn.

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