BLSM

EX-99.1

2 d266261dex991.htm

EX-99.1

EX-99.1

Exhibit 99.1

BlossomHill Therapeutics Reports Second Quarter 2026 Financial Results

Strengthened balance sheet with successful completion of upsized $168.3 million initial public offering

Announced FDA Fast Track designation for BH-30643 for the treatment of advanced

EGFR C797S-positive NSCLC

SAN DIEGO,

September 18, 2026 – BlossomHill Therapeutics, Inc. (Nasdaq: BLSM), a clinical-stage biopharmaceutical company applying an intentional, chemistry-based approach to design and develop innovative small molecule medicines for the treatment of cancer, today announced financial results for the second quarter 2026 and highlighted recent progress.

“We’ve achieved meaningful progress across our pipeline, as well as our significant corporate milestones, since the beginning of the second quarter,” said Jean Cui, Ph.D., Founder, President and Chief Executive Officer of BlossomHill Therapeutics. “In April, we presented our first preclinical data from our pseudo-irreversible pan-KRAS inhibitor BH-501284, built on a novel chemical scaffold, at AACR where we highlighted the sustained target engagement leading to tumor regression at low dose levels. At ASCO in early June we presented the preliminary safety, PK and antitumor activities of BH-30643 in Phase 1 dose escalation of the SOLARA trial, along with the initial efficacy data in C797S-positive NSCLC. More recently we announced that BH-30643 received Fast Track designation, an important regulatory milestone that reflects the FDA’s recognition of the potential for this molecule. We also presented encouraging safety data and early signs of anti-leukemic activity observed with BH-30236, our novel macrocyclic CLK inhibitor, both as a monotherapy and in combination with venetoclax, at EHA in the middle of June. We are now looking forward to our end-of-phase 1 meeting with the FDA later this year. With a strong balance sheet following our successful initial public offering in August, we believe we are well positioned to deliver important clinical and regulatory milestones over the coming quarters as we continue advancing our intentionally designed medicines that address significant unmet medical needs in cancer treatment.”

Recent Business Highlights and Corporate Updates:

•

Strengthened the balance sheet with approximately $168.3 million in gross proceeds from the initial public offering (IPO) in August 2026

•

Announced the U.S. Food and Drug Administration (FDA) granted Fast Track designation to BH-30643, a macrocyclic OMNI-EGFR™ inhibitor, for the treatment of adult patients with advanced or metastatic epidermal growth factor receptor (EGFR) C797S-positive non-small cell lung cancer (NSCLC) after prior treatment with a third-generation EGFR tyrosine kinase inhibitor (TKI)

•

Presented preliminary results of BH-30643 from dose escalation and

backfill cohorts in the ongoing Phase 1/2 SOLARA trial in advanced or metastatic EGFR-mutant NSCLC at the American Society of Clinical Oncology (ASCO) 2026 annual meeting, and additional follow up data at IASLC 2026 World Conference on Lung Cancer, which highlighted a 45% objective response rate and 88% disease control rate observed in patients with C797S resistance to prior TKIs, with or without concurrent T790M mutation

•

Presented the first preclinical data from the pseudo-irreversible

pan-KRAS inhibitor BH-501284, built on a novel chemical scaffold, at the American Association for Cancer Research (AACR) 2026 annual meeting

•

Presented initial clinical data from the ongoing first-in-human Phase 1/1b trial of BH-30236, an orally bioavailable, macrocyclic CDC-like kinase (CLK) inhibitor, in relapsed or refractory acute myeloid leukemia (R/R AML) and higher-risk myelodysplastic syndromes (HR-MDS) at the European Hematology Association (EHA) 2026 Congress

•

Expanded the Company’s Board of Directors with the appointments of Sheila Gujrathi, M.D., and John Schmid

Anticipated Upcoming Milestones:

BH-30643

•

Q4 2026: End of Phase 1 meeting regarding a recommended Phase 2 dose selection and a potential accelerated approval pathway in C797S resistance

•

Q1 2027: First patient dosed in anticipated pivotal Phase 2 trial

•

1H 2027: Updated Phase 1 data, including C797S durability

•

2H 2027: Updated Phase 1 data on TKI-naive durability and initial chemo combo cohort data

BH-501284

•

Q1 2027: Investigational New Drug submission

BH-30236

•

1H 2027: Updated Phase 1 data on safety and anti-leukemic effect

Second Quarter 2026 Financial Results

Research and development (R&D) expenses for the second quarter of 2026 were $21.4 million, compared with $12.5 million for the same period in 2025. The increase was primarily due to greater clinical development expenses driven by the SOLARA trial, expenses to support IND-enabling studies for BH-501284, and greater costs related to personnel, facilities and other overhead.

General and administrative (G&A) expenses for the second quart