NovaBridge Biosciences

NovaBridge Biosciences 2440 Research Boulevard, Suite 400 Rockville, MD 20850 (Address of principal executive offices) Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F. Form 20-F ☒ Form 40-F ☐

NovaBridge Biosciences (the "Company") reports that clinical data from the ongoing Phase 1 clinical trial of ragistomig (also known as "ABL503"or"TJ-L14B"), a bispecific antibody targeting both PD-L1 and 4-1BB being jointly developed by the Company and ABL Bio Inc. ("ABL Bio"), were presented in a poster at the European Society for Medical Oncology (ESMO) Congress 2026 by ABL Bio in Madrid, Spain, on October 23, 2026. Incorporation by Reference The information set forth in this report on Form 6-K shall be deemed to be incorporated by reference into the Company's Registration Statements on Form F-3 (File No. 333-286954) and Form S-8 (File No. 333-239871, File No. 333-256603, File No. 333-265684, File No. 333-279842, File No. 333-290195 and File No. 333-298369) (including any prospectuses forming a part of such registration statements) and to be a part thereof from the date on which this Form 6-K is furnished, to the extent not superseded by documents or reports subsequently filed or furnished.

99.1 Poster - Dose Optimization of Ragistomig (ABL503/TJ-L14B), a PD-L1x 4-1BBBispecific Antibody