Olema Oncology Announces Encouraging Initial Clinical Data from the Phase 1 Study of OP-3136, a KAT6 Inhibitor, at 2026 ASCO Annual Meeting (Form 8-K)

Olema Oncology Announces Encouraging Initial Clinical Data from the Phase 1 Study of OP-3136, a KAT6 Inhibitor, at 2026 ASCO Annual Meeting

SAN FRANCISCO, May 21, 2026 (Globe NewsWire) - Olema Pharmaceuticals, Inc. ("Olema" or "Olema Oncology", Nasdaq: OLMA), a clinical-stage biopharmaceutical company focused on the discovery, development, and commercialization of targeted therapies for breast cancer and beyond, today announced preliminary clinical data from the Phase 1 study of OP-3136, a potent lysine acetyltransferase 6 (KAT6) inhibitor. The data will be presented in a poster presentation on May 30, 2026 at the American Society of Clinical Oncology (ASCO) Annual Meeting taking place in Chicago, Illinois. Olema will also present a trial-in-progress poster for the Phase 3 OPERA-02 trial of palazestrant in combination with ribociclib in frontline estrogen receptor-positive, human epidermal growth factor receptor 2-negative (ER+/HER2-) metastatic breast cancer.

"We are pleased to share the initial Phase 1 data for OP-3136, which demonstrated acceptable tolerability and promising anti-tumor activity as a monotherapy across multiple dose levels in various advanced solid tumor types," said Sean P. Bohen, M.D., Ph.D., President and Chief Executive Officer of Olema Oncology. "The decreases in tumor size observed in over two-thirds of evaluable patients and evidence of on-target engagement reinforce our confidence in OP-3136 as a potential best-in-class KAT6 inhibitor and a potentially differentiated option for difficult-to-treat cancers. We look forward to progressing OP-3136 in development, particularly in combination with palazestrant in metastatic breast cancer."

The Phase 1 study evaluates dose escalation followed by dose expansion of OP-3136 in patients with ER+/HER2- advanced breast cancer (ABC), metastatic castration-resistant prostate cancer (mCRPC), and metastatic non-small cell lung cancer (mNSCLC). In Part 1A, OP-3136 monotherapy was administered orally once daily in 28-day cycles across dose levels from 2 mg to 45 mg. As of the March 2, 2026 data cut-off, 32 heavily pretreated patients who became resistant or intolerant to standard of care treatments were enrolled in this cohort.

Key Findings

Safety and Tolerability

Efficacy and Target Engagement

Pharmacokinetics

"These initial results from the Phase 1 study of OP-3136, including confirmed and durable responses and a manageable safety profile in a heavily pretreated population, underscore the potential of KAT6 inhibition as a therapeutic strategy in different solid tumor types," said Amita Patnaik, MD, FRCPC, Principal Investigator, Co-Founder, and Co-Director of Clinical Research at the START Center for Cancer Research. "Supported by evidence of target engagement and predictable pharmacokinetics across all doses evaluated to date, I am excited to further evaluate this novel therapy, both as a monotherapy and in combination with multiple agents, as Phase 1 development continues."

OP-3136 Poster Presentation Details

Title: A phase 1, first-in-human study of OP-3136, a novel oral selective KAT6A/B inhibitor, as monotherapy in advanced solid tumors and in combination with endocrine therapy in ER+, HER2- advanced breast cancer: preliminary results

Abstract Number: 3088

Poster Number: 225

Date/Time: May 30, 2026 from 1:30pm-4:30pm CT / 2:30pm-5:30pm ET

OPERA-02 Trial-in-Progress Poster Presentation Details

Olema will also present a trial-in-progress poster for the Phase 3 OPERA-02 trial of palazestrant in combination with ribociclib in frontline ER+/HER2- metastatic breast cancer.

Title: OPERA-02: A phase 3 study of palazestrant plus ribociclib as first-line treatment of ER+, HER2- advanced breast cancer

Abstract Number: TPS1152

Poster Number: 261b

Date/Time: June 1, 2026 from 1:30pm-4:30pm CT / 2:30pm-5:30pm ET

Copies of these posters will be available on the Publications page of Olema's website in alignment with the ASCO embargo. Additional information, including abstracts, is available on the ASCO Annual Meeting website.

About Olema Oncology

Olema Oncology is a clinical-stage biopharmaceutical company committed to transforming the standard of care and improving outcomes for patients living with breast cancer and beyond. Olema is advancing a pipeline of novel therapies by leveraging our deep understanding of endocrine-driven cancers, nuclear receptors, and mechanisms of acquired resistance. Our lead product candidate, palazestrant (OP-1250), is a proprietary, orally available complete estrogen receptor antagonist (CERAN) and a selective estrogen receptor degrader (SERD), currently in two Phase 3 clinical trials. In addition, Olema is developing OP-3136, a potent lysine acetyltransferase 6 (KAT6) inhibitor, now in a Phase 1 clinical study. Olema is headquartered in San Francisco and has operations in Cambridge, Massachusetts. For more information, please visit www.olema.com.

About OP-3136

OP-3136 is a novel, orally available small molecule that potently and selectively inhibits lysine acetyltransferase 6 (KAT6), an epigenetic target that is dysregulated in breast and other cancers. In preclinical studies, OP-3136 has demonstrated significant anti-proliferative activity in ER+ breast cancer models and is combinable and synergistic with endocrine therapies, including palazestrant and cyclin-dependent kinase 4/6 (CDK4/6) inhibitors. The Investigational New Drug (IND) application for OP-3136 was cleared by the U.S. Food and Drug Administration (FDA) in December 2024 and patients are currently enrolling in the Phase 1 clinical study.