Company Overview

Company Description

We are a clinical-stage oncology company dedicated to unlocking a new paradigm in cancer therapeutics that addresses the significant unmet need in patients with oncogene amplified tumors by targeting extrachromosomal DNA (ecDNA), a root cause of oncogene amplification observed in more than 14% of cancer patients. Our mission is to be the foremost biopharma company interrogating ecDNA biology to deliver transformative therapies that improve and extend the lives of patients with previously intractable oncogene amplified cancers.

ecDNA are large circular units of nuclear DNA that are a primary mechanism of gene amplification and, like oncogene amplifications, are detected only in cancer cells, not in healthy cells. Despite tremendous advancements in treating cancer broadly, patients with oncogene amplified cancers generally derive little benefit from existing therapies, such as molecular targeted therapies or immunotherapies, and have worse survival rates than patients with other types of cancer. Using our proprietary Spyglass platform, we identify targets essential for ecDNA functionality in oncogene amplified cancer cells, then design and develop small molecule drugs called ecDNA-directed therapeutic candidates (ecDTx) to inhibit those targets, with the aim to prevent cancer cells from using ecDNA to express amplified oncogenes and grow, adapt, and become resistant to existing therapies. Instead of directly targeting the proteins produced by amplified oncogenes, which is the approach of traditional targeted therapies, our ecDTx are intended to be synthetic lethal in tumor cells reliant on ecDNA. In the context of drug development, synthetic lethality is a therapeutic approach wherein using a drug to pharmacologically inhibit one target is lethal to cancer cells harboring a specific genetic alteration to a second target, but not lethal to healthy cells that lack the genetic alteration to the second target. Accordingly, our ecDTx are designed to preferentially kill ecDNA-bearing cancer cells, but not healthy cells without ecDNA. They are engineered to disrupt the underlying cellular machinery that enables ecDNA to function properly, such as proteins essential for ecDNA replication, transcription, assembly, repair, and segregation.

Our lead ecDTx, BBI-355, is a novel, oral, selective inhibitor of checkpoint kinase 1 (CHK1), which manages ecDNA replication and transcription in cancer cells. BBI-355 demonstrated CHK1 inhibition and tumor regressions in ecDNA-enabled preclinical cancer models and is currently being studied in a first-in-human, Phase 1/2 clinical trial in patients with oncogene amplified cancers. We refer to this trial as POTENTIATE (Precision Oncology Trial Evaluating Novel Therapeutic Interrupting Amplifications Tied to ecDNA). We expect to have preliminary clinical proof of concept safety and antitumor activity data of BBI-355 as a single agent and in combination with targeted therapies from the POTENTIATE trial in the second half of 2024 from approximately 50 to 90 total enrolled patients (single agent cohorts N=~30 to 40, combination cohorts N=~20 to 50). Our second ecDTx, BBI-825, is a novel, oral, selective inhibitor of ribonucleotide reductase (RNR), which is essential for ecDNA assembly and repair in cancer cells. BBI-825 demonstrated RNR inhibition and tumor regressions in amplification-enabled preclinical cancer models. In February 2024, we initiated a first-in-human, Phase 1/2 clinical trial of BBI-825 in patients with resistance gene amplifications. We refer to this trial as STARMAP (Study Treating Acquired Resistance: MAPK Amplifications). We expect to have preliminary clinical proof of concept safety and antitumor activity data of BBI-825 in combination with targeted therapies from the STARMAP trial in the second half of 2025. Our third ecDTx program is directed at a previously undrugged kinesin target essential for ecDNA segregation and inheritance during cell division. We are advancing our third ecDTx program through drug discovery to candidate identification and expect to submit an investigational new drug application (IND) as early as the first half of 2026.

To assist in identifying patients that may benefit from our ecDTx, we have developed an ecDNA diagnostic, which we internally call ECHO (ecDNA Harboring Oncogenes), to detect ecDNA in patient tumor samples. This test analyzes the genomic data output from routine next-generation sequencing (NGS) assays that are commonly used by commercial reference and academic laboratories to profile patient tumor samples. We are working with an in vitro diagnostic company to develop this diagnostic test into a clinical trial assay, which we intend to use in our ongoing Phase 1/2 POTENTIATE clinical trial. The FDA has determined that the ecDNA diagnostic is a non-significant risk device when used in patient selection for the POTENTIATE trial, meaning that we will not be required to obtain FDA approval of an Investigational Device Exemption (IDE) for the use of the ecDNA diagnostic in this trial.

Our current pipeline consists of three ecDTx programs directed against three different ecDNA targets, as well as our ecDNA diagnostic. We also continue to identify new ecDNA targets, both novel and previously clinically validated, through our proprietary Spyglass platform. We have built our Spyglass platform to identify specific, druggable targets essential to ecDNA formation and function in cancer cells. To our knowledge, Spyglass is the only platform in the biopharma industry focused on identifying ecDNA-enabled vulnerabilities in cancer. All of our ecDTx have been discovered internally, and we retain global rights for all of our programs.

As we are, to our knowledge, the first company formed to develop new cancer medicines directed at ecDNA and the only company to date to bring an ecDTx into the clinic to treat cancer patients, we consider ourselves to be the world’s leading ecDNA company. Our efforts build on the work of our scientific founders and advisors, including Dr. Paul Mischel, who is a globally recognized leader in the ecDNA field, having authored more than 20 peer-reviewed publications on ecDNA and the team leader for the National Institute of Health’s (NIH) and Cancer Research United Kingdom’s (CRUK) Cancer Grand Challenges team devoted to ecDNA and its role in cancer. Dr. Mischel is the Chairman of our Scientific Advisory Board. We leverage this unique expertise to identify new cancer targets that are synthetic lethal in ecDNA-bearing cancer cells and to develop new medicines for patients with oncogene amplified cancers.

We were originally founded as a Delaware corporation on April 10, 2018 under the name Pretzel Therapeutics, Inc. On July 8, 2019, we changed our name to Boundless Bio, Inc. Our principal executive offices are located at 9880 Campus Point Drive, Suite 120, San Diego, CA 92121, and our telephone number is (858) 766-9912. Our website address is www.boundlessbio.com.