Financial Performance - Cash position as of September 30, 2024, is $167.1 million, providing an operating runway into the fourth quarter of 2026[6] - Net loss for Q3 2024 totaled $16.5 million, compared to a net loss of $13.2 million in Q3 2023, indicating a 25% increase in losses[6] - Total operating expenses for Q3 2024 were $18.7 million, compared to $15.0 million in Q3 2023, marking an increase of 25.5%[13] - Accumulated deficit as of September 30, 2024, was $185.0 million, compared to $136.1 million at the end of 2023[13] Research and Development - Research and development (R&D) expenses for Q3 2024 were $14.1 million, up from $11.6 million in Q3 2023, representing a 21.5% increase[6] - Initial proof-of-concept data for BBI-355 and BBI-825 clinical trials is expected in the second half of 2025[3][4] - The company is advancing its third ecDTx program, ecDTx 3, through lead optimization[4] General and Administrative Expenses - General and administrative (G&A) expenses for Q3 2024 were $4.6 million, compared to $3.3 million in Q3 2023, reflecting a 39.4% increase[6] Assets and Financial Position - Total assets as of September 30, 2024, were $175.1 million, up from $129.9 million at the end of 2023[13] Clinical Trials and Diagnostics - ECHO, the proprietary diagnostic for detecting ecDNA amplified oncogenes, is currently being used in the BBI-355 POTENTIATE trial[5]

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 ...