Exhibit 99.1 Boundless Bio Reports Third Quarter 2024 Financial Results and Business Highlights Enrollment progressing in BBI-355 POTENTIATE and BBI-825 STARMAP clinical trials, with initial proof-ofconcept data expected in the second half of 2025 Cash position of $167 million, with operating runway into the fourth quarter of 2026 SAN DIEGO, November 7, 2024 – Boundless Bio (Nasdaq: BOLD), a clinical-stage oncology company interrogating extrachromosomal DNA (ecDNA) biology to deliver transformative therapie ...

Exhibit 99.1 Boundless Bio Provides Business Updates Focused on Key Value Drivers and Reports Second Quarter 2024 Financial Results BBI-355 POTENTIATE clinical trial ongoing with initiatives implemented to expedite enrollment in combination cohorts; initial proof-of-concept data now expected in the second half of 2025 BBI-825 STARMAP clinical trial ongoing with initial proof-of-concept data expected in the second half of 2025 ECHO ecDNA diagnostic analytically validated and IRB-approved for use as a clinica ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 Title of each class Trading Symbol(s) Name of each exchange on which registered Common stock, par value $0.0001 per share BOLD Nasdaq Global Select Market FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2024 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from ______ ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 Title of each class Trading Symbol(s) Name of each exchange on which registered Common stock, par value $0.0001 per share BOLD Nasdaq Global Select Market FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2024 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from _____ ...

Exhibit 99.1 Boundless Bio Reports First Quarter 2024 Financial Results and Corporate Highlights BBI-355 Phase 1/2 POTENTIATE clinical trial ongoing; initiated targeted therapy combinations in patients with tumors with EGFR or FGFR oncogene amplifications First patient dosed in Phase 1/2 STARMAP clinical trial of BBI-825 in patients with tumors with resistance gene amplifications Completed $100 million IPO; pro forma cash position of approximately $200 million supports both BBI-355 and BBI-825 through preli ...