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First-in-Human Study of RLY-5836 in Advanced Breast Cancer and Other Solid Tumors

A First-in-Human Study of PI3Kα Inhibitor, RLY-5836, in Combination With Targeted and Endocrine Therapies in Participants With Advanced Breast Cancer and as a Single Agent in Advanced Solid Tumors

Status
Completed
Phases
Phase 1
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT05759949
Enrollment
41
Registered
2023-03-08
Start date
2023-03-29
Completion date
2025-04-11
Last updated
2025-05-16

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

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

Brief summary

This is a Phase 1, first-in-human, open-label study designed to evaluate the maximum tolerated dose (MTD), recommended phase 2 dose (RP2D), safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary anti-tumor activity of RLY-5836 in advanced solid tumors in participants harboring a PIK3CA mutation in blood and/or tumor per local assessment. The study consists of 2 parts, a dose escalation (Part 1) and a dose expansion (Part 2).

Interventions

DRUGRLY-5836

RLY-5836 is a mutant-selective, oral PI3Kα inhibitor.

DRUGFulvestrant

Fulvestrant (500 mg) is administered IM into the buttocks (gluteal area) slowly (1 to 2 minutes per injection) as 2×5 mL injections, 1 in each buttock, on Cycle 1 Day 1, Cycle 1 Day 15, and Day 1 of each subsequent cycle.

DRUGPalbociclib

Palbociclib 125 mg once daily is taken orally in combination with RLY-5836 and fulvestrant for 28-day cycles that include 21 days of treatment followed by 7 days off treatment.

DRUGRibociclib

Ribociclib 600 mg once daily is taken orally in combination with RLY-5836 and fulvestrant for 28-day cycles that include 21 days of treatment followed by 7 days off treatment.

DRUGAbemaciclib

Abemaciclib 150 mg BID will be taken orally in combination with RLY-5836 and fulvestrant for 28-day cycles.

Sponsors

Relay Therapeutics, Inc.
Lead SponsorINDUSTRY

Study design

Allocation
NON_RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
NONE

Eligibility

Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No

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 RLY-5836 single agent arm key inclusion criteria * Disease that is refractory to standard therapy, intolerant to standard therapy, or participant has declined standard therapy. * A histologically or cytologically confirmed diagnosis of unresectable or metastatic solid tumor Combination arms key inclusion criteria * Males, postmenopausal females, or pre-/perimenopausal females previously treated with gonadotropin-releasing GnRH agonist at least 4 weeks prior to start of study drug with histologically or cytologically confirmed diagnosis of HR+, HER2- unresectable or metastatic breast cancer that is not amenable to curative therapy. * Had previous treatment for advanced or metastatic breast cancer with antiestrogen therapy including, but not limited to, selective estrogen receptor degraders (e.g., fulvestrant), selective estrogen receptor modulators (e.g., tamoxifen), and aromatase inhibitors (AI) (letrozole, anastrozole, exemestane) * Part 1: Prior PI3Kα inhibitor treatment is allowed if taken for \< 14 days and not discontinued due to disease progression, hypersensitivity, or ≥ Grade 3 TEAEs.

Exclusion criteria

* Part 2: Prior treatment with PI3Kα inhibitors. * Type 1 or Type 2 diabetes requiring antihyperglycemic medication, or fasting plasma glucose ≥140 mg/dL and glycosylated hemoglobin (HbA1c) ≥7.0%.

Design outcomes

Primary

MeasureTime frame
Number of participants with serious adverse events (SAEs)Every cycle (4-week cycles) until study discontinuation, approximately 24 months
Maximum Tolerated Dose (MTD) and Recommended Phase 2 Dose (RP2D) of RLY-5836Cycle 1 (4-week cycle) of treatment for MTD and at the end of every cycle (4-week cycles) for RP2D until study discontinuation, approximately 24 months
Number of participants with any dose-limiting toxicity (DLT)Cycle 1, up to 28 days.
Number of participants with adverse events (AEs)Every cycle (4-week cycles) until study discontinuation, approximately 24 months

Secondary

MeasureTime frame
PK of RLY-5836: maximum plasma concentration (Cmax)Approximately every 2 weeks in Cycle 1 (4-week cycle) and every cycle through end of treatment (4-week cycles), approximately 24 months
PK of RLY-5836: time to maximum concentration (tmax)Approximately every 2 weeks in Cycle 1 (4-week cycle) and every cycle through end of treatment (4-week cycles), approximately 24 months
PK of RLY-5836: half-life (t½)Approximately every 2 weeks in Cycle 1 (4-week cycle) and every cycle through end of treatment (4-week cycles), approximately 24 months
PK of RLY-5836: clearance following oral dose (CL/F)Approximately every 2 weeks in Cycle 1 (4-week cycle) and every cycle through end of treatment (4-week cycles), approximately 24 months
Preliminary antitumor activity of RLY-5836: disease control rate (DCR) per Response Evaluation Criteria in Solid Tumors (RECIST Version 1.1)Approximately every 8 weeks until progressive disease, approximately 36 months
Changes in circulating markers of glucose metabolism: changes in circulating insulinApproximately every week in Cycle 1 (4-week cycle), every 2 weeks in Cycle 2 (4-week cycle), and every cycle through end of treatment (4-week cycles), approximately 24 months
Changes in circulating markers of glucose metabolism: changes in circulating C-peptideApproximately every week in Cycle 1 (4-week cycle), every 2 weeks in Cycle 2 (4-week cycle), and every cycle through end of treatment (4-week cycles), approximately 24 months
Changes in circulating markers of glucose metabolism: changes in circulating glycosylated hemoglobin [HbA1c]Approximately every week in Cycle 1 (4-week cycle), every 2 weeks in Cycle 2 (4-week cycle), and every cycle through end of treatment (4-week cycles), approximately 24 months
Preliminary antitumor activity of RLY-5836: duration of response (DOR) per Response Evaluation Criteria in Solid Tumors (RECIST Version 1.1)Approximately every 8 weeks until progressive disease, approximately 36 months
Changes in circulating markers of glucose metabolism: changes in circulating glucoseApproximately every week in Cycle 1 (4-week cycle), every 2 weeks in Cycle 2 (4-week cycle), and every cycle through end of treatment (4-week cycles), approximately 24 months
Preliminary antitumor activity of RLY-5836: objective response rate (ORR) per Response Evaluation Criteria in Solid Tumors (RECIST Version 1.1)Approximately every 8 weeks until progressive disease, approximately 36 months
PIK3CA genotype in blood and tumor tissue by next generation nucleic acid sequencingEvery cycle (4-week cycles) through Cycle 3 and every other cycle thereafter until study discontinuation, approximately 24 months
PK of RLY-5836: area under the concentration-time curve (AUC)Approximately every 2 weeks in Cycle 1 (4-week cycle) and every cycle through end of treatment (4-week cycles), approximately 24 months

Countries

United States

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 6, 2026