First-in-Human Study of Mutant-selective PI3Kα Inhibitor, RLY-2608, as a Single Agent in Patients With Advanced Solid Tumors and in Combination With Endocrine Therapy +/- a CDK4/6 or CDK4 Inhibitor in Patients With Advanced Solid Tumors or Advanced Breast Cancer

NCT ID: NCT05216432

Last Updated: 2025-09-22

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

RECRUITING

Clinical Phase

PHASE1

Total Enrollment

930 participants

Study Classification

INTERVENTIONAL

Study Start Date

2021-12-08

Study Completion Date

2027-04-30

Brief Summary

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This is an open-label, FIH study designed to evaluate the maximum tolerated dose, recommended Phase 2 dose, safety, tolerability, PK, pharmacodynamics, and preliminary antineoplastic activity of RLY-2608, in advanced solid tumor patients with a Phosphatidylinositol-4,5-bisphosphate-3 kinase, catalytic subunit alpha (PIK3CA) mutation in blood and/or tumor per local assessment. The study will evaluate RLY-2608 as a single agent for patients with unresectable or metastatic solid tumors. It will also evaluate RLY-2608 in combination RLY-2608 + fulvestrant and in triple combination RLY-2608 + fulvestrant + CDK4/6 inhibitor (palbociclib or ribociclib) or CDK4 inhibitor (PF-07220060) for patients with HR+ HER2- locally advanced or metastatic breast cancer. The RLY-2608 single agent arm, RLY-2608 + fulvestrant combination arm, and triple combination arms will have 2 parts: a dose escalation (Part 1) and a dose expansion (Part 2).

Detailed Description

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Conditions

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PIK3CA Mutation Solid Tumor, Adult HER2-negative Breast Cancer Breast Cancer Metastatic Breast Cancer Advanced Breast Cancer Unresectable Solid Tumor

Study Design

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Allocation Method

NON_RANDOMIZED

Intervention Model

PARALLEL

Single Agent Arm:

Part 1(multiple ascending doses, QD or BID):unresectable or metastatic solid tumors with PIK3CA mutation per local assessment; Part 2 (RP2D determined in Part 1) Patients with unresectable or metastatic solid tumors with ≥1 PIK3CA mutation per local assessment will be enrolled protocol defined groups

Double Combination Arm Part 1(multiple ascending doses, QD or BID): HR+, HER2- locally advanced or metastatic breast cancer with PIK3CA mutation per local assessment Part 2 (RP2D determined in Part 1) Group 1: patients who have not received prior PI3Kα inhibitor Group 2: patients who are intolerant to PI3Kα inhibitor

Triple Combination Arms Part 1(multiple ascending doses, QD or BID): HR+, HER2- locally advanced or metastatic breast cancer with PIK3CA mutation per local assessment

Part 2 (RP2D determined in Part 1) Patients with HR+, HER2-locally advanced or metastatic breast cancer with PIK3CA mutation per local assessment will be enrolled in protocol defined groups
Primary Study Purpose

TREATMENT

Blinding Strategy

NONE

Study Groups

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RLY-2608 for patients with unresectable or metastatic solid tumors

Multiple doses of RLY-2608 for oral administration.

Group Type EXPERIMENTAL

RLY-2608

Intervention Type DRUG

RLY-2608 is a mutant-selective, oral PI3Kα inhibitor.

RLY-2608 + fulvestrant combination for HR+ HER2- locally advanced or metastatic breast cancer

Oral dose of RLY-2608 in addition to fulvestrant as determined during Part 1 Dose Escalation.

Group Type EXPERIMENTAL

RLY-2608

Intervention Type DRUG

RLY-2608 is a mutant-selective, oral PI3Kα inhibitor.

Fulvestrant

Intervention Type DRUG

500 mg fulvestrant is administered intramuscularly on Cycle 1 Day 1, Day 15, and Day 1 of each subsequent cycle (where a cycle is 28 days).

RLY-2608+fulvestrant+palbo125mg for HR+HER2- locally advanced metastatic breast cancer

Oral dose of RLY-2608 in addition to fulvestrant and palbociclib 125mg as determined during Part 1 Dose Escalation.

Group Type EXPERIMENTAL

RLY-2608

Intervention Type DRUG

RLY-2608 is a mutant-selective, oral PI3Kα inhibitor.

Fulvestrant

Intervention Type DRUG

500 mg fulvestrant is administered intramuscularly on Cycle 1 Day 1, Day 15, and Day 1 of each subsequent cycle (where a cycle is 28 days).

Palbociclib 125mg

Intervention Type DRUG

125mg palbociclib is taken orally once daily for 28-day cycles that include 21 days of treatment followed by 7 days off treatment.

RLY-2608+fulvestrant+ribo400mg for HR+HER2- locally advanced metastatic breast cancer

Oral dose of RLY-2608 in addition to fulvestrant and ribociclib 400mg as determined during Part 1 Dose Escalation.

Group Type EXPERIMENTAL

RLY-2608

Intervention Type DRUG

RLY-2608 is a mutant-selective, oral PI3Kα inhibitor.

Fulvestrant

Intervention Type DRUG

500 mg fulvestrant is administered intramuscularly on Cycle 1 Day 1, Day 15, and Day 1 of each subsequent cycle (where a cycle is 28 days).

Ribociclib 400mg

Intervention Type DRUG

400mg ribociclib is taken orally once daily for 28-day cycles that include 21 days of treatment followed by 7 days off treatment.

RLY-2608+fulvestrant+ribo600mg for HR+HER2- locally advanced metastatic breast cancer

Oral dose of RLY-2608 in addition to fulvestrant and ribociclib 600mg as determined during Part 1 Dose Escalation.

Group Type EXPERIMENTAL

RLY-2608

Intervention Type DRUG

RLY-2608 is a mutant-selective, oral PI3Kα inhibitor.

Fulvestrant

Intervention Type DRUG

500 mg fulvestrant is administered intramuscularly on Cycle 1 Day 1, Day 15, and Day 1 of each subsequent cycle (where a cycle is 28 days).

Ribociclib 600mg

Intervention Type DRUG

600mg ribociclib is taken orally once daily for 28-day cycles that include 21 days of treatment followed by 7 days off treatment.

RLY-2608+fulvestrant+PF-07220060 100 mg for HR+ HER2- locally advanced or metastatic breast cancer

Oral dose of RLY-2608 in addition to fulvestrant and PF-07220060 100 mg as determined during Part 1 Dose Escalation

Group Type EXPERIMENTAL

RLY-2608

Intervention Type DRUG

RLY-2608 is a mutant-selective, oral PI3Kα inhibitor.

Fulvestrant

Intervention Type DRUG

500 mg fulvestrant is administered intramuscularly on Cycle 1 Day 1, Day 15, and Day 1 of each subsequent cycle (where a cycle is 28 days).

PF-07220060 100mg

Intervention Type DRUG

PF-07220060 100 mg is taken orally twice daily at the same time with RLY-2608 during each 28-day cycle.

RLY-2608+fulvestrant+PF-07220060 300 mg for HR+ HER2- locally advanced or metastatic breast cancer

Oral dose of RLY-2608 in addition to fulvestrant and PF-07220060 300 mg as determined during Part 1 Dose Escalation

Group Type EXPERIMENTAL

RLY-2608

Intervention Type DRUG

RLY-2608 is a mutant-selective, oral PI3Kα inhibitor.

Fulvestrant

Intervention Type DRUG

500 mg fulvestrant is administered intramuscularly on Cycle 1 Day 1, Day 15, and Day 1 of each subsequent cycle (where a cycle is 28 days).

PF-07220060 300 mg

Intervention Type DRUG

PF-07220060 300 mg is taken orally twice daily at the same time with RLY-2608 during each 28-day cycle.

Interventions

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RLY-2608

RLY-2608 is a mutant-selective, oral PI3Kα inhibitor.

Intervention Type DRUG

Fulvestrant

500 mg fulvestrant is administered intramuscularly on Cycle 1 Day 1, Day 15, and Day 1 of each subsequent cycle (where a cycle is 28 days).

Intervention Type DRUG

Palbociclib 125mg

125mg palbociclib is taken orally once daily for 28-day cycles that include 21 days of treatment followed by 7 days off treatment.

Intervention Type DRUG

Ribociclib 400mg

400mg ribociclib is taken orally once daily for 28-day cycles that include 21 days of treatment followed by 7 days off treatment.

Intervention Type DRUG

Ribociclib 600mg

600mg ribociclib is taken orally once daily for 28-day cycles that include 21 days of treatment followed by 7 days off treatment.

Intervention Type DRUG

PF-07220060 100mg

PF-07220060 100 mg is taken orally twice daily at the same time with RLY-2608 during each 28-day cycle.

Intervention Type DRUG

PF-07220060 300 mg

PF-07220060 300 mg is taken orally twice daily at the same time with RLY-2608 during each 28-day cycle.

Intervention Type DRUG

Other Intervention Names

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Faslodex Ibrance Kisqali Kisqali

Eligibility Criteria

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Inclusion Criteria

Patient has ECOG performance status of 0-1

One or more documented primary oncogenic PIK3CA mutation(s) in blood and/or tumor per local assessment

Other potentially oncogenic PIK3CA mutations may be considered but must be approved by the Sponsor prior to enrollment.

Part 1 \[Escalation\] - Ability to provide archived tumor tissue or be willing to undergo pretreatment tumor biopsy to assess PIK3CA status retrospectively Part 2 \[Expansion\] - Submit tumor tissue prior to study drug initiation for determination of PIK3CA mutation retrospectively.

Key Inclusion for RLY-2608 Single Agent Arm

* \[For Part 1: Escalation\]: Evaluable disease per RECIST v1.1
* \[For Part 2: Expansion\]: Measurable disease per RECIST v1.1
* Disease that is refractory to standard therapy, intolerant to standard therapy, or has declined standard therapy.
* Part 1- histologically or cytologically confirmed diagnosis of unresectable or metastatic solid tumor
* Part 2 - Unresectable or metastatic solid tumor with PIK3CA mutation(s) and one of the following tumor types:

Group 1: clear cell ovarian cancer Group 2: head and neck squamous cell carcinoma Group 3: cervical cancer Group 4: other solid tumors, excluding colorectal, clear cell ovarian, head and neck squamous cell, and cervical cancers Group 5: unresectable or metastatic solid tumors with PIK3CA double mutations In addition, the SRC (with Sponsor approval) may choose to open additional group(s) of 20 participants to study the clinical activity, safety, and PK/PD with other specified solid tumor types.

Key Inclusion for Combination Arms:

* Doublet combination arms \[Part 1 and Part 2\]: Evaluable disease per RECIST v1.1
* Triplet combination arms:
* \[Part 1 and Part 2 Dose Expansion, Group 1\]: Evaluable disease per RECIST.
* \[Part 2 Dose Expansion, Group 2\]: Measurable disease per RECIST. Bone-only lytic or lytic/blastic disease with at least 1 measurable soft-tissue component per RECIST may be eligible.
* \[For Part 1 and Part 2\]: Male or female with histologically or cytologically confirmed diagnosis of HR+, HER2- unresectable or metastatic breast cancer that is not amenable to curative therapy. Females may be postmenopausal, premenopausal, or perimenopausal. Premenopausal or perimenopausal females must have a histologically or cytologically confirmed diagnosis of HR+ HER2- locally advanced or metastatic breast cancer that is not amenable to curative therapy and must have initiated treatment with a gonadotropin-releasing hormone (GnRH) agonist at least 4 weeks prior to start of study drug with continuation of GnRH agonist for the duration of study treatment (GnRH agonist recommended for males).
* Had previous treatment for breast cancer with: \[Does not apply to triplet combination arms, Part 2 Dose Expansion, Group 2\]:

1. ≤1 line of chemotherapy in the metastatic setting
2. ≥1 CDK4/6 inhibitor in either the adjuvant and/or metastatic setting
3. ≥1 antiestrogen therapy in either adjuvant and/or metastatic setting, including, but not limited to, selective estrogen-receptor degraders (eg, fulvestrant), selective estrogen receptor modulators (eg, tamoxifen), and aromatase inhibitors (AI) (letrozole, anastrozole, exemestane), and
4. ≥1 PARP inhibitor, if appropriate, if documented germline BRCA1/2 mutation Note: Systemic local, loco-regional, or adjuvant treatment with chemotherapy and PARP inhibitors is not to be included in enumeration or previous treatment

\[For double combination arm; Part 2 Dose Expansion, Group 2\]: Received prior treatment with a PI3Kα, AKT, or mTOR inhibitor and discontinued the inhibitor due to intolerance and not disease progression, where intolerance is defined as treatment discontinuation due to treatment related AE (eg. hyperglycemia, rash, diarrhea, stomatitis) other than severe hypersensitivity reaction and/or life-threatening reactions, such as anaphylaxis and Stevens-Johnson syndrome.

\[For triple combination arms; Part 1 dose escalation\]: Participants who had previous treatment for breast cancer with PI3Kα, AKT, mTOR inhibitors and discontiuned due to participant/physician decision, intolerance, or disease progression will be considered.

\[For triple combination arms, Part 2 Dose Expansion, Group 2\]: Participants must be intolerant to or have declined standard therapy for locally advanced or metastatic HR+/HER2- PIK3CA-mutated breast cancer. Prior endocrine therapy and CDK4/6inhibitors are allowed as follows:

1. Participants must have progressed during (neo)adjuvant endocrine therapy or within12 months of completing (neo)adjuvant endocrine therapy with an AI or tamoxifen.
2. If a CDK4/6 inhibitor was included as part of (neo)adjuvant therapy, disease must have recurred/progressed \>12 months after completion of the CDK4/6 inhibitor portion of (neo)adjuvant therapy

Exclusion Criteria

Prior treatment with:

1. PI3Kα, AKT, or mTOR inhibitors (all arms except for doublet RLY-2608 + fulvestrant arm, Part 2, Group 2; and triplet combinations, Part 1 dose escalation).
2. Immune checkpoint inhibitors.
3. Triplet combinations RLY-2608 + CDK4 or CDK4/6 inhibitor + fulvestrant, Part 2 expansion, Group 2 only:

i. Prior systemic chemotherapy or antibody drug conjugate for locally advanced or metastatic disease. ii. Prior CDK2, CDK4, or CDK4/6 inhibitor as treatment for locally advanced or metastatic disease.

iii. Prior treatment with fulvestrant or any selective ER degrader, with the exception of patients who have received fulvestrant or any selective ER degrader as part of neoadjuvant therapy only and with treatment duration ≤6 months.

Type 1 or Type 2 diabetes requiring antihyperglycemic medication, or fasting plasma glucose ≥140 mg/dL and glycosylated hemoglobin (HbA1c) ≥7.0%.

History of allergy or hypersensitivity to any components or excipients of PI3K inhibitors. For combination arms only: allergy or hypersensitivity to any components or excipients of fulvestrant, palbociclib, ribociclib, and/or PF-07220060 as appropriate for the combination.

Past medical history of or ongoing ILD, or pneumonitis requiring intervention. Participants with past history of resolved Grade 1 pneumonitis may be considered, except in triple combination arms.

The following cardiac criteria:

* Mean resting corrected QT interval (QTc) \>460 msec
* For triple combination arm with ribociclib: Mean QTcF ≥450 msec (this is what we confirmed is shown in the redacted version of the protocol.

CNS metastases or primary CNS tumor that is associated with progressive neurologic symptoms
Minimum Eligible Age

18 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

No

Sponsors

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Relay Therapeutics, Inc.

INDUSTRY

Sponsor Role lead

Responsible Party

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Responsibility Role SPONSOR

Locations

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The University of Arizona Cancer Center

Tucson, Arizona, United States

Site Status RECRUITING

University of California-San Diego

San Diego, California, United States

Site Status RECRUITING

HealthONE

Denver, Colorado, United States

Site Status RECRUITING

Yale University

New Haven, Connecticut, United States

Site Status RECRUITING

Florida Cancer Specialists

Orlando, Florida, United States

Site Status RECRUITING

Boca Raton Clinical Research (BRCR) Global

Plantation, Florida, United States

Site Status WITHDRAWN

University of Chicago Medical Center

Chicago, Illinois, United States

Site Status RECRUITING

Community Health Network

Indianapolis, Indiana, United States

Site Status RECRUITING

Massachusetts General Hospital

Boston, Massachusetts, United States

Site Status RECRUITING

Dana-Farber Cancer Institute

Boston, Massachusetts, United States

Site Status RECRUITING

University of Michigan

Ann Arbor, Michigan, United States

Site Status RECRUITING

Washington University School of Medicine St. Louis

St Louis, Missouri, United States

Site Status RECRUITING

Renown Regional Medical Center

Reno, Nevada, United States

Site Status RECRUITING

Rutgers University

New Brunswick, New Jersey, United States

Site Status RECRUITING

NYU Langone

New York, New York, United States

Site Status RECRUITING

Columbia University Herbert Irving Comprehensive Cancer Center

New York, New York, United States

Site Status RECRUITING

Memorial Sloan Kettering

New York, New York, United States

Site Status RECRUITING

Tennessee Oncology

Nashville, Tennessee, United States

Site Status RECRUITING

University of Texas Southwestern Medical Center

Dallas, Texas, United States

Site Status RECRUITING

The University of Texas M.D. Anderson Cancer Center

Houston, Texas, United States

Site Status RECRUITING

University of Utah- Huntsman Cancer Center

Salt Lake City, Utah, United States

Site Status RECRUITING

Inova Schar Cancer Center

Fairfax, Virginia, United States

Site Status RECRUITING

NEXT Virginia

Fairfax, Virginia, United States

Site Status RECRUITING

UW Carbone Cancer Center

Madison, Wisconsin, United States

Site Status RECRUITING

St Vincents Hospital

Sydney, New South Wales, Australia

Site Status RECRUITING

Peter MacCallum Cancer Center

Melbourne, Victoria, Australia

Site Status RECRUITING

The Alfred Hospital

Melbourne, Victoria, Australia

Site Status RECRUITING

Centre Léon Bérard

Lyon, Auvergne-Rhône-Alpes, France

Site Status RECRUITING

Institute Bergonié

Bordeaux, , France

Site Status RECRUITING

Gustave Roussy

Villejuif, , France

Site Status RECRUITING

Istituto Europeo di Oncologia IRCCS

Milan, , Italy

Site Status RECRUITING

Vall d'Hebron Instituto de Oncologia

Barcelona, Barcelona, Spain

Site Status RECRUITING

START Barcelona

Barcelona, Catalonia, Spain

Site Status RECRUITING

Instituto Valenciano de Oncologia

Valencia, Valencia, Spain

Site Status RECRUITING

Institut Catala D'Oncologia - Badalona (ICO Badalona)

Barcelona, , Spain

Site Status RECRUITING

START Madrid - Hospital Fundacion Jimenez Diaz

Madrid, , Spain

Site Status RECRUITING

Hospital Universitario 12 de Octubre

Madrid, , Spain

Site Status RECRUITING

Countries

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United States Australia France Italy Spain

Central Contacts

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Relay Therapeutics Inc

Role: CONTACT

617-322-0731

Other Identifiers

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RLY-2608-101

Identifier Type: -

Identifier Source: org_study_id

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