Relay Therapeutics (RLAY) shows 11.1-month PFS with zovegalisib combo in PI3Kα-mutated breast cancer
Rhea-AI Filing Summary
Relay Therapeutics reported new Phase 1/2 data for its PI3Kα inhibitor zovegalisib combined with fulvestrant at the recommended Phase 3 dose of 400mg twice daily with food in PI3Kα‑mutated, HR+/HER2- metastatic breast cancer.
Among 57 efficacy-evaluable patients as of the January 13, 2026 cut-off, median progression-free survival was 11.1 months, with similar outcomes for kinase and non‑kinase mutations. In 35 patients with measurable disease, the confirmed objective response rate was 43%, and 52% in second-line-only patients. The regimen was generally well tolerated in 60 treated patients, with mostly low‑grade, manageable adverse events, a hyperglycemia profile dominated by Grade 1 events, and only four discontinuations due to treatment-related side effects. These data support use of the 400mg fed dose in the ongoing global Phase 3 ReDiscover‑2 trial, for which the combination has FDA Breakthrough Therapy designation.
Positive
- Encouraging efficacy at Phase 3 dose: At the 400mg BID fed regimen, median progression-free survival reached 11.1 months and confirmed objective response rate was 43% (52% in second-line-only patients) in heavily pre-treated PI3Kα-mutated HR+/HER2- metastatic breast cancer.
- Manageable safety profile: The combination showed primarily low-grade, reversible treatment-related adverse events, Grade 1–dominant hyperglycemia and only four discontinuations among 60 treated patients, supporting its selection as the recommended Phase 3 dose.
- Advancement into Phase 3 with FDA Breakthrough Therapy designation: The same 400mg BID fed dose is being used in the ongoing global Phase 3 ReDiscover-2 trial, and the regimen has received FDA Breakthrough Therapy designation for that trial population.
Negative
- None.
Insights
Zovegalisib shows encouraging efficacy and tolerability at its Phase 3 dose.
The data describe zovegalisib plus fulvestrant at 400mg BID fed in heavily pre‑treated PI3Kα‑mutated HR+/HER2- metastatic breast cancer. Median progression‑free survival of 11.1 months and a confirmed objective response rate of 43% suggest meaningful antitumor activity in a resistant setting.
Safety appears manageable, with mostly low‑grade, reversible treatment‑related events, Grade 1‑dominated hyperglycemia and only four discontinuations among 60 treated patients. Pharmacokinetic analyses indicate exposures comparable to the earlier 600mg BID fasted dose, supporting the lower, more convenient fed regimen as the recommended Phase 3 dose.
The regimen is already being tested in the global Phase 3 ReDiscover‑2 trial using this 400mg BID fed dose and has FDA Breakthrough Therapy designation for that population. Future readouts from ReDiscover‑2 will be important to confirm whether these early efficacy and safety trends translate into registrational‑quality outcomes.
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SECURITIES AND EXCHANGE COMMISSION
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FORM 8-K
CURRENT REPORT
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Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).
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Item 7.01 Regulation FD Disclosure.
On March 16, 2026, Relay Therapeutics, Inc. (the "Company") issued a press release announcing the data from the Phase 1/2 ReDiscover trial of zovegalisib (RLY-2608) in combination with fulvestrant at the recommended Phase 3 dose of 400mg twice daily ("BID") taken with food (fed) in patients with PI3Kα-mutated, HR+/HER2- metastatic breast cancer, a copy of which is furnished herewith as Exhibit 99.1 to this Current Report on Form 8-K.
The information in this Item 7.01, including Exhibit 99.1 attached hereto, is intended to be furnished and shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934 (the "Exchange Act"), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such filing.
Item 8.01 Other Events.
On March 16, 2026, the Company announced data from the Phase 1/2 ReDiscover trial of zovegalisib in combination with fulvestrant at the 400mg BID fed dose, which is the recommended Phase 3 dose, at the European Society for Medical Oncology Targeted Anticancer Therapies Congress 2026.
Zovegalisib is currently being evaluated in the ReDiscover trial, an ongoing first-in-human study designed to evaluate the safety, tolerability, pharmacokinetics, pharmacodynamics and preliminary antitumor activity of zovegalisib in combination with fulvestrant and in combination with fulvestrant and CDK inhibitors in patients with PI3Kα-mutated, HR+/HER2- metastatic breast cancer.
As of the January 13, 2026 data cut-off date (the "Data Cut-off Date"), 60 patients had received the 400mg BID fed regimen. The efficacy population consisted of 57 patients who did not have a PTEN or AKT co-mutation, consistent with the planned pivotal population. All patients had previously received a CDK4/6 inhibitor and at least one prior endocrine therapy in the advanced setting.
Pharmacokinetic analyses demonstrated that the 400mg BID fed regimen achieved exposures comparable to the previously evaluated 600mg BID fasted dose, with mean concentrations approaching IC90 in majority of patients and nearly all patients maintaining exposure above the IC80 throughout the dosing interval.
As of the Data Cut-off Date, among the 57 efficacy-evaluable patients at the 400mg BID fed dose:
Zovegalisib in combination with fulvestrant at the 400mg BID fed dose was generally well tolerated in the 60 treated patients as of the Data Cut-off Date. The overall tolerability profile consisted primarily of low-grade, manageable and reversible treatment-related adverse events ("TRAEs").
Cautionary Note Regarding Forward Looking Statements
This Current Report on Form 8-K and certain materials furnished or filed herewith contain forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended, including, without limitation, implied and express statements regarding the Company's strategy, business plans and focus; the progress and timing of the clinical development of the programs across the Company's portfolio; the expected therapeutic benefits and potential efficacy and tolerability of zovegalisib, both as a monotherapy and in combination with other agents, and its other programs, as well as the clinical data for zovegalisib; the interactions with regulatory authorities and any related approvals; and the potential commercialization and market opportunity for zovegalisib. The words "may," "might," "will," "could," "would," "should," "plan," "anticipate," "intend," "believe," "expect," "estimate," "seek," "predict," "future," "project," "potential," "continue," "target" and similar words or expressions, or the negative thereof, are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words.
Any forward-looking statements in this Current Report on Form 8-K and certain materials furnished or filed herewith are based on management's current expectations and beliefs and are subject to a number of risks, uncertainties and important factors that may cause actual events or results to differ materially from those expressed or implied by any forward-looking statements contained in this Current Report on Form 8-K and certain materials furnished or filed herewith, including, without limitation, risks associated with: the impact of global economic uncertainty, geopolitical instability and conflicts, or public health epidemics or outbreaks of an infectious disease on countries or regions in which the Company has operations or does business, as well as on the timing and anticipated results of its clinical trials, strategy, future operations and profitability; significant political, trade or regulatory developments, such as tariffs, beyond the Company’s control; the delay or pause of any current or planned clinical trials or the development of the Company's drug candidates; the risk that the preliminary or interim results of its preclinical or clinical trials may not be predictive of future or final results in connection with future clinical trials of its product candidates and that interim and early clinical data may change as more patient data become available and are subject to audit and verification procedures; the Company's ability to successfully demonstrate the safety and efficacy of its drug candidates; the timing and outcome of its planned interactions with regulatory authorities; and obtaining, maintaining and protecting its intellectual property. These and other risks and uncertainties are described in greater detail in the section entitled "Risk Factors" in the Company's most recent Annual Report on Form 10-K and Quarterly Report on Form 10-Q, as well as any subsequent filings with the Securities and Exchange Commission. In addition, any forward-looking statements represent the Company's views only as of today and should not be relied upon as representing its views as of any subsequent date. The Company explicitly disclaims any obligation to update any forward-looking statements. No representations or warranties (expressed or implied) are made about the accuracy of any such forward-looking statements.
Item 9.01 Financial Statements and Exhibits.
99.1 |
Press Release issued by Relay Therapeutics, Inc. on March 16, 2026, furnished herewith. |
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Cover Page Interactive Data File (embedded within Inline XBRL document). |
SIGNATURES
Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.
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Relay Therapeutics, Inc. |
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March 16, 2026 |
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/s/ Soo-Yeun Lim |
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Soo-Yeun Lim |
Exhibit 99.1
Relay Therapeutics Announces Data from Zovegalisib + Fulvestrant at the Phase 3 Dose of
400mg BID Fed at ESMO Targeted Anticancer Therapies Congress 2026
400mg BID fed is the dose used in the ongoing Phase 3 ReDiscover-2 trial, which initiated mid-2025
11.1-month median PFS in heavily pre-treated patients with PI3Kα-mutated, HR+/HER2- metastatic breast cancer
Efficacy in patients with kinase and non-kinase domain mutations is similar,
with median PFS of 11.2 and 11.0 months, respectively
Safety and tolerability data are consistent with 600mg BID fasted data
Zovegalisib has received FDA Breakthrough Therapy designation for the Phase 3 ReDiscover-2 trial population
Cambridge, Mass. – March 16, 2026 – Relay Therapeutics, Inc. (Nasdaq: RLAY), a clinical-stage, small molecule precision medicine company developing potentially life-changing therapies for patients living with cancer and genetic disease, today announced data from the Phase 1/2 ReDiscover trial of zovegalisib (RLY-2608) + fulvestrant at the recommended Phase 3 dose of 400mg twice daily (BID) taken with food (fed) in patients with PI3Kα-mutated, HR+/HER2- metastatic breast cancer. The data are being presented at the European Society for Medical Oncology (ESMO) Targeted Anticancer Therapies (TAT) Congress 2026 in Paris, France.
“As supported by the data presented, the 400mg BID fed regimen maintains robust efficacy with a safety profile consistent with mutant-selective PI3Kα inhibition,” said Don Bergstrom, M.D., Ph.D., President of R&D at Relay Therapeutics. “These results further support our decision to advance this regimen into the ongoing Phase 3 ReDiscover-2 trial and reinforce our confidence in selectively targeting PI3Kα mutations as a potentially differentiated approach for CDK4/6-experienced patients.”
Phase 1/2 ReDiscover Trial – Zovegalisib 400mg Fed Cohort Data Consistent with 600mg Fasted Data
Zovegalisib is currently being evaluated in ReDiscover, an ongoing first-in-human study designed to evaluate the safety, tolerability, pharmacokinetics, pharmacodynamics and preliminary antitumor activity of zovegalisib in combination with fulvestrant and in combination with fulvestrant and CDK inhibitors in patients with PI3Kα-mutated, HR+/HER2- metastatic breast cancer.
As of the January 13, 2026 data cut-off date, 60 patients had received the 400mg BID fed regimen. The efficacy population consisted of 57 patients who did not have a PTEN or AKT co-mutation, consistent with the planned pivotal population. All patients had previously received a CDK4/6 inhibitor and at least one prior endocrine therapy in the advanced setting.
Pharmacokinetics of Both Doses are Similar
Pharmacokinetic analyses demonstrate that the 400mg BID fed regimen achieves exposures comparable to the previously evaluated 600mg BID fasted dose, with mean concentrations approaching IC90 in majority of patients and nearly all patients maintaining exposure above the IC80 throughout the dosing interval.
Efficacy Consistent with 600mg BID Fasted
As of the January 13, 2026 data cut-off date, among the 57 efficacy-evaluable patients at the 400mg BID fed dose, which is the recommended Phase 3 dose (RP3D):
Maintained Favorable and Differentiated Tolerability Profile
Zovegalisib + fulvestrant at the 400mg BID fed dose was generally well tolerated in the 60 treated patients as of the January 13, 2026 data cut-off. The overall tolerability profile consisted primarily of low-grade, manageable and reversible treatment-related adverse events (TRAEs).
The data presentation from the ESMO TAT Congress 2026 is available on the Relay Therapeutics website in the “Publications/Presentations” section through the following link: https://relaytx.com/publications.
ReDiscover-2 – Ongoing Phase 3 Trial
The Phase 3 ReDiscover-2 trial (NCT06982521) is evaluating zovegalisib 400mg BID administered in combination with fulvestrant versus capivasertib + fulvestrant in patients with PI3Kα-mutated, HR+/HER2- advanced breast cancer who have progressed on prior CDK4/6 inhibitor therapy. The study initiated in mid-2025 and is enrolling globally.
Zovegalisib + fulvestrant has received FDA Breakthrough Therapy designation for the Phase 3 ReDiscover-2 trial population.
About Zovegalisib
Zovegalisib is the lead program in Relay Therapeutics’ efforts to discover and develop mutant selective inhibitors of PI3Kα, the most frequently mutated kinase in all cancers and all vascular anomalies. Zovegalisib has the potential, if approved, to address a significant portion of the approximately 140,000 patients with HR+/HER2- breast cancer with a PI3Kα mutation and the estimated 170,000 patients with vascular anomalies driven by a PI3Kα mutation per year in the United States, one of the largest patient populations for a precision medicine.
Traditionally, the development of PI3Kα inhibitors has focused on the active, or orthosteric, site. The therapeutic index of orthosteric inhibitors is limited by the lack of clinically meaningful selectivity for mutant versus wild-type (WT) PI3Kα and off-isoform activity. Toxicity related to inhibition of WT PI3Kα and other PI3K isoforms results in sub-optimal inhibition of mutant PI3Kα with reductions in dose intensity and frequent discontinuation. The Dynamo® platform enabled the discovery of zovegalisib, the first known allosteric, pan-mutant, and isoform-selective PI3Kα inhibitor, designed to overcome these limitations. Relay Therapeutics solved the full-length cryo-EM structure of PI3Kα, performed computational long time-scale molecular dynamic simulations to elucidate conformational differences between WT and mutant PI3Kα, and leveraged these insights to support the design of zovegalisib. Zovegalisib is currently being evaluated in multiple metastatic breast cancer studies and a first-in-human study designed to treat patients with PIK3CA (PI3Kα) mutation driven vascular anomalies. For more information on zovegalisib, please visit here.
About Relay Therapeutics
Relay Therapeutics (Nasdaq: RLAY) is a clinical-stage, small molecule precision medicine company developing potentially life-changing therapies for patients living with cancer and genetic disease. Relay's Dynamo® platform integrates an array of leading-edge computational and experimental approaches designed to drug protein targets that have previously been intractable or inadequately addressed. The company’s lead clinical asset, zovegalisib, is the first pan-mutant selective PI3Kα inhibitor to enter clinical development and is currently in a Phase 3 clinical trial (ReDiscover-2) in HR+/HER2- metastatic breast cancer. Zovegalisib is also being investigated in a group of genetic disease indications called PI3Kα-driven vascular anomalies. Relay's pipeline also includes programs for NRAS-driven solid tumors and Fabry disease. For more information, please visit www.relaytx.com or follow us on LinkedIn.
Cautionary Note Regarding Forward-Looking Statements
This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended, including, without limitation, implied and express statements regarding Relay Therapeutics’ strategy, business plans and focus; the progress and timing of the clinical development of the programs across Relay Therapeutics’ portfolio; the timing of clinical data readouts for zovegalisib; the expected therapeutic benefits and potential efficacy and tolerability of zovegalisib, both as a monotherapy and in combination with other agents, and its other programs; the clinical data for zovegalisib; the interactions with regulatory authorities and any related approvals; and the potential commercialization and market opportunity for zovegalisib. The words “may,” “might,” “will,” “could,” “would,” “should,” “plan,” “anticipate,” “intend,” “believe,” “expect,” “estimate,” “seek,” “predict,” “future,” “project,” “potential,” “continue,” “target” and similar words or expressions, or the negative thereof, are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words.
Any forward-looking statements in this press release are based on management's current expectations and beliefs and are subject to a number of risks, uncertainties and important factors that may cause actual events or results to differ materially from those expressed or implied by any forward-looking statements contained in this press release, including, without limitation, risks associated with: the impact of global economic uncertainty, geopolitical instability and conflicts, or public health epidemics or outbreaks of an infectious disease on countries or regions in which Relay Therapeutics has operations or does business, as well as on the timing and anticipated results of its clinical trials, strategy, future operations and profitability; significant political, trade or regulatory developments, such as tariffs, beyond Relay Therapeutics’ control; the delay or pause of any current or planned clinical trials or the development of Relay Therapeutics’ drug candidates; the risk that the preliminary or interim results of its preclinical or clinical trials may not be predictive of future or final results in connection with future clinical trials of its product candidates and that interim and early clinical data may change as more patient data become available and are subject to audit and verification procedures; Relay Therapeutics’ ability to successfully demonstrate the safety and efficacy of its drug candidates; the timing and outcome of its planned interactions with regulatory authorities; and obtaining, maintaining and protecting its intellectual property. These and other risks and uncertainties are described in greater detail in the section entitled “Risk Factors” in Relay Therapeutics’ most recent Annual Report on Form 10-K and Quarterly Report on Form 10-Q, as well as any subsequent filings with the Securities and Exchange Commission. In addition, any forward-looking statements represent Relay Therapeutics' views only as of today and should not be relied upon as representing its views as of any subsequent date. Relay Therapeutics explicitly disclaims any obligation to update any forward-looking statements. No representations or warranties (expressed or implied) are made about the accuracy of any such forward-looking statements.
Contact:
Pete Rahmer
prahmer@relaytx.com
Media:
Dan Budwick
1AB
973-271-6085
dan@1abmedia.com
FAQ
What clinical results did Relay Therapeutics (RLAY) report for zovegalisib?
How well tolerated was zovegalisib 400mg BID fed in the ReDiscover trial for RLAY?
Why did Relay Therapeutics select the 400mg BID fed dose of zovegalisib for Phase 3?
What is the Phase 3 ReDiscover-2 trial mentioned by Relay Therapeutics (RLAY)?
Does zovegalisib have FDA Breakthrough Therapy designation for Relay Therapeutics?
What patient population was included in the zovegalisib 400mg BID fed efficacy analysis?
Filing Exhibits & Attachments
2 documentsPress Releases
