Boundless Bio Updates on Key Value Drivers and Q2 2024 Financial Results

Boundless Bio, a clinical-stage oncology company based in San Diego, is committed to pioneering innovative cancer treatments for patients with oncogene amplified cancers. These patients, who typically have limited therapeutic options, may benefit significantly from Boundless Bio's focus on targeting extrachromosomal DNA (ecDNA) biology. The company recently shared updates on its strategic priorities and financial results for the second quarter of 2024.

During the second quarter, Boundless Bio made strides in its clinical programs. The company continued to advance its first clinical-stage ecDNA-directed therapeutic candidate (ecDTx), BBI-355, and began dosing patients with its second ecDTx, BBI-825. Additionally, Boundless Bio completed the analytical validation and received IRB approval for its novel ecDNA diagnostic, ECHO, for use in the BBI-355 POTENTIATE trial.

However, the enrollment pace in the combination cohorts of the BBI-355 POTENTIATE trial has been slower than expected. To address this, Boundless Bio has implemented several measures to expedite enrollment, including engaging with next-generation sequencing vendors to identify eligible patients and adding new clinical sites in the U.S., with preparations underway for ex-U.S. sites. Consequently, the company now expects to report initial proof-of-concept data from the POTENTIATE trial in the second half of 2025.

Boundless Bio has also outlined its core strategic priorities through 2025, focusing on advancing its lead programs. These priorities include executing the ongoing Phase 1/2 POTENTIATE trial for BBI-355 in solid tumor cancer patients with driver oncogene amplifications, and the Phase 1/2 STARMAP trial for BBI-825 in colorectal cancer patients with BRAFV600E or KRASG12C mutations and resistance oncogene amplifications. The company is also advancing its third ecDTx program, targeting a previously undrugged kinesin essential for ecDNA segregation, into IND-enabling studies. Additionally, Boundless Bio is deploying its proprietary ecDNA diagnostic to identify patients most likely to benefit from its ecDTx therapeutics.

In line with its strategic priorities, Boundless Bio has streamlined its operations and reduced its workforce to extend its operating runway. The company believes these measures, along with its cash, cash equivalents, and short-term investments totaling $179.3 million as of June 30, 2024, will support its operations into the fourth quarter of 2026.

The company's lead ecDTx, BBI-355, is a novel, oral, selective CHK1 inhibitor designed to exploit replication stress in cancer cells with oncogene amplification, including those on ecDNA. Preclinical and clinical pharmacodynamic data on BBI-355 were presented at the American Association for Cancer Research (AACR) Annual Meeting in April 2024. Enrollment is ongoing in the Phase 1/2 POTENTIATE trial, and no new safety signals or combinatorial toxicity have been observed thus far.

BBI-825, Boundless Bio's second ecDTx, is a novel, oral, selective RNR inhibitor targeting ecDNA assembly and repair in cancer patients with resistance oncogene amplifications. The first patient was dosed with BBI-825 in April 2024, and multiple dose levels have been completed in the single-agent, dose-escalation portion of the STARMAP trial. The drug has demonstrated oral bioavailability and has been generally well-tolerated. Initial clinical proof-of-concept data from the trial are anticipated in the second half of 2025.

The company's third ecDTx program is focused on a novel kinesin target essential for ecDNA segregation. This program is currently advancing through lead optimization.

ECHO, Boundless Bio's proprietary ecDNA diagnostic, is designed to detect ecDNA in patient tumor specimens. It has been analytically validated and IRB-approved for use in the BBI-355 POTENTIATE trial.

Financially, Boundless Bio reported a cash position of $179.3 million as of June 30, 2024. Research and development expenses for the second quarter of 2024 were $14.7 million, compared to $11.1 million for the same period in 2023. General and administrative expenses were $4.7 million, compared to $2.9 million in the prior-year period. The net loss for the second quarter of 2024 totaled $17.0 million, compared to $12.4 million for the same period in 2023.

Boundless Bio remains dedicated to advancing its innovative ecDNA-targeted therapies and addressing the significant unmet needs of patients with oncogene amplified tumors.