Olema Oncology Announces Encouraging Initial Clinical Data from the Phase 1 Study of OP-3136, a KAT6 Inhibitor, at 2026 ASCO Annual Meeting
Rhea-AI Summary
Olema Oncology (Nasdaq: OLMA) reported initial Phase 1 data for OP-3136, an oral KAT6 inhibitor, in advanced solid tumors. OP-3136 monotherapy showed no dose-limiting toxicities up to 45 mg daily, manageable side effects, and evidence of anti-tumor activity with partial responses and target engagement.
AI-generated analysis. Not financial advice.
Positive
- No dose-limiting toxicities observed for OP-3136 up to 45 mg once daily
- No treatment discontinuations due to treatment-related adverse events in 32 patients
- Tumor shrinkage in 13 of 19 response-evaluable patients across tumor types
- Three partial responses observed, including two confirmed, in measurable disease
- Eleven patients remain on OP-3136 treatment, with longest duration at 62 weeks
- Steady-state concentrations at ≥6 mg exceeded preclinical efficacy targets
Negative
- Dysgeusia reported as treatment-related adverse event in 81% of patients
- Grade 3 anemia occurred in 6% and grade 3 neutropenia in 28% of patients
News Market Reaction – OLMA
On the day this news was published, OLMA declined 2.70%, reflecting a moderate negative market reaction. Argus tracked a peak move of +2.3% during that session. Argus tracked a trough of -10.0% from its starting point during tracking. Our momentum scanner triggered 10 alerts that day, indicating notable trading interest and price volatility. This price movement removed approximately $34M from the company's valuation, bringing the market cap to $1.23B at that time.
Data tracked by StockTitan Argus on the day of publication.
Key Figures
Market Reality Check
Peers on Argus
OLMA was up 6.56% while key biotech peers were mixed: ARVN (+0.83%), BCAX (+2.91%), VSTM (+4.4%), SAGE (-0.69%), ORKA (-1.46%). Moves do not indicate a broad sector rotation.
Previous Clinical trial Reports
| Date | Event | Sentiment | Move | Catalyst |
|---|---|---|---|---|
| Apr 21 | ASCO data preview | Positive | -0.6% | Announced upcoming OP-3136 Phase 1 and OPERA-02 posters for ASCO 2026. |
| Sep 02 | Pfizer trial pact | Positive | +18.5% | New Phase 1b/2 collaboration combining palazestrant with Pfizer’s atirmociclib. |
| Apr 25 | OP-3136 preclinical | Positive | -3.7% | Reported OP-3136 anti-tumor activity across multiple solid tumor models at AACR. |
| Dec 10 | Palazestrant combo data | Positive | +2.1% | Updated palazestrant plus ribociclib results with favorable PFS and benefit rates. |
| Oct 23 | Preclinical combo data | Positive | -4.4% | Shared OP-3136 and palazestrant preclinical synergy and anti-tumor activity at ENA. |
Clinical and preclinical updates have produced mixed reactions, with 3 of 5 tagged clinical trial events followed by negative next-day moves despite generally positive scientific news.
Over the past year, Olema has steadily advanced palazestrant and OP-3136. In October 2024 and April 2025, the company reported preclinical OP-3136 data showing anti-tumor activity and synergy with palazestrant. Subsequent clinical updates in December 2024 for palazestrant plus ribociclib and in April 2026 outlining OP-3136 ASCO presentations continued this progression. A September 2025 Pfizer collaboration in ER+/HER2- breast cancer drew a strong positive price response, highlighting market interest in late-stage, partnered programs.
Historical Comparison
Over the last five clinical-trial-related announcements, OLMA’s average next-day move was 2.38%. The pre-news gain of 6.56% sat above that typical reaction range.
Clinical-trial-tagged news shows a progression from OP-3136 preclinical work to first-in-human Phase 1 data, alongside advancing palazestrant combinations and a Pfizer collaboration in ER+/HER2- metastatic breast cancer.
Market Pulse Summary
This announcement highlighted early but encouraging OP-3136 Phase 1 results, including tumor shrinkage in 13 of 19 response-evaluable patients, confirmed partial responses, and no dose-limiting toxicities up to 45 mg daily. It also reinforced Olema’s broader strategy around palazestrant combinations and the OPERA-02 Phase 3 trial. Investors may watch for durability of responses, expansion cohort data, and how OP-3136 combinations compare with existing metastatic breast cancer options.
Key Terms
dose-limiting toxicities medical
metastatic castration-resistant prostate cancer medical
metastatic non-small cell lung cancer medical
lysine acetyltransferase 6 medical
pharmacokinetics medical
AI-generated analysis. Not financial advice.
- OP-3136 monotherapy was well-tolerated with no dose-limiting toxicities observed and no discontinuations due to treatment-related adverse events
- OP-3136 shows evidence of anti-tumor activity across multiple solid tumor types
- Data support the ongoing Phase 1 evaluation of OP-3136 as a monotherapy and in combination with fulvestrant and palazestrant
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
- OP-3136 monotherapy was well-tolerated with no dose-limiting toxicities observed across the evaluated daily dose range up to 45 mg per day orally.
- Most treatment-related adverse events (TRAEs) were grade 1 or 2; no grade 4 or 5 TRAEs were observed. TRAEs were manageable with dose modifications; no treatment discontinuations occurred due to TRAEs.
- The most common TRAEs were dysgeusia (
81% any grade;56% grade 1,25% grade 2), anemia (38% any grade;6% grade 3), and neutropenia (34% any grade;28% grade 3).
Efficacy and Target Engagement
- Among 19 response-evaluable patients across dose levels and tumor types, tumor shrinkage was observed in 13 patients; partial responses (PR) were observed in 3 patients with measurable disease, with 2 confirmed PRs and 1 unconfirmed PR.
- The longest duration of treatment is 62 weeks.
- 11 patients remain on treatment, including 9 with ABC and 2 with mCRPC.
- Across all doses tested, OP-3136 demonstrated rapid, sustained, and significant reduction in levels of lysine 23 of histone H3, a direct target of KAT6, consistent with on-target KAT6 inhibition.
Pharmacokinetics
- OP-3136 exhibited predictable, dose-proportional plasma exposure across all doses tested.
- At doses of 6 mg and above, steady-state concentrations exceeded efficacy targets based on preclinical models.
“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.
Forward-Looking Statements
Statements contained in this press release regarding matters that are not historical facts are “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. Words such as “anticipate,” “believe,” “could,” “expect,” “goal,” “intend,” “may,” “on track,” “potential,” “upcoming,” “will” and similar expressions (as well as other words or expressions referencing future events, conditions or circumstances) are intended to identify forward-looking statements. These statements include those related to the potential beneficial characteristics including but not limited to safety, tolerability, activity, efficacy and therapeutic effects of OP-3136 and the combinability of OP-3136 with other therapies, including palazestrant and fulvestrant; the potential of OP-3136 to be a best-in-class KAT6 inhibitor and differentiated therapy for difficult-to-treat cancers; and the continued development and advancement of OP-3136, including in combination with other therapies such as fulvestrant and palazestrant. Because such statements deal with future events and are based on Olema’s current expectations, they are subject to various risks and uncertainties, and actual results, performance, or achievements of Olema could differ materially from those described in or implied by the statements in this press release. These forward-looking statements are subject to risks and uncertainties, including, without limitation, those discussed in the section titled “Risk Factors” in Olema’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2026, and future filings and reports that Olema makes from time to time with the U.S. Securities and Exchange Commission. Except as required by law, Olema assumes no obligation to update these forward-looking statements, including in the event that actual results differ materially from those anticipated in the forward-looking statements.
Media and Investor Relations Contact
Courtney O’Konek
Vice President, Corporate Communications
Olema Oncology
media@olema.com
