> Trialight public data. Index of pages: https://trialight.com/llms.txt
> Web page: https://trialight.com/data/trial/first-in-human-study-of-tersolisib-stx-478-as-monotherapy-281c6acd-8b34-4767-a985-3022d47a201c
> Record changed: 2026-10-13

# First-in-Human Study of Tersolisib (STX-478) as Monotherapy and in Combination With Other Antineoplastic Agents in Participants With Advanced Solid Tumors

NCT05768139

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

Phase

Phase 1/Phase 2

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

Recruitment status

Recruiting

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

Participants

880

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

Lead sponsor

Eli Lilly and Company

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

Start date

2023-04-17

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

Number of sites

65

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

## Title and summary

**Summary**

Study STX-478-101 (LY4064809) is a multipart, open-label, phase 1/2 study evaluating the safety, tolerability, pharmacokinetics (PK), and preliminary antitumor activity of STX-478 (LY4064809) in participants with advanced solid tumors with P13Ka mutations. Part 1 will evaluate STX-478 as monotherapy in participants with advanced solid tumors. Part 2 will evaluate STX-478 therapy as combination therapy with fulvestrant in participants with hormone receptor positive (HR+) breast cancer. Part 3 will evaluate STX-478 as combination therapy with endocrine therapy (aromatase inhibitors, fulvestrant, tamoxifen, or imlunestrant) and a CDK4/6 Inhibitor (either Ribociclib, Palbociclib or Abemaciclib) in participants with HR+ breast cancer. Each study part will include a 28-day screening period, followed by treatment with STX-478 monotherapy or combination therapy.

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

**Acronym**

PIKALO-1

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

**Short title**

First-in-Human Study of Tersolisib (STX-478) as Monotherapy and in Combination With Other Antineoplastic Agents in Participants With Advanced Solid Tumors

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

**Official title**

First-in-Human Study of STX-478, a Mutant-Selective PI3Kα Inhibitor as Monotherapy and in Combination With Other Antineoplastic Agents in Participants With Advanced Solid Tumors

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

## Status and phase

**Control arm**

Open label

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

**Registry reports results**

No

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

**Listing at source**

Listed

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

**Recruitment status**

Recruiting

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

**Phase**

Phase 1/Phase 2

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

**Study type**

Interventional

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

## Dates

**Completion date**

2030-07-01

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

**First posted**

2023-03-14

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

**Registry last updated**

2026-07-07

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

**Primary completion date**

2030-07-01

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

**Start date**

2023-04-17

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

## Size and sites

**Participants**

880

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

**Participant count basis**

Estimated

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

**Planned participants**

880

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

**Protocol amendments**

9

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

**Number of sites**

65

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

## Sponsor and oversight

**Registry sponsor category**

Industry

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

**Lead sponsor**

Eli Lilly and Company

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

**Source registry**

ClinicalTrials.gov

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

## Identifiers

**Registry ID**

NCT05768139

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

**ClinicalTrials.gov ID**

NCT05768139

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

**Registry record**

Open registry record

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

## Study design

**Allocation**

Not randomised

**Model**

Sequential

**Purpose**

Treatment

**Masking**

No masking

**Masking description**

In Part 1, Part 2 B0, B2, and B3, and Part 3 C0, D0, E0, F and A8, participants are assigned to intervention. In Part 2 B1 and Part 3 C1, D1, and E1, participants are randomized to doses

Sources for study design

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

## Outcomes

### Primary outcomes

1. Number of participants who experience at least 1 Dose Limiting Toxicity (DLT)  
Timeframe: First 28 days of treatment
2. Proportion of participants who experience at least 1 DLT during the first 28 days of treatment  
Timeframe: First 28 days of treatment
3. Objective response rate (ORR) defined as the percentage of participants with partial response or complete response based on RECIST 1.1  
Timeframe: 12 months
4. Incidence of TEAEs/SAEs ≥ grade 2  
Timeframe: 12 months
5. Frequency of TEAEs according to CTCAE v5.0 criteria  
Timeframe: 12 months

### Secondary outcomes

1. Cmax of STX-478  
Timeframe: 12 months
2. AUC(0-inf) of STX-478  
Timeframe: 12 months
3. AUC(0-t) of STX-478  
Timeframe: 12 months
4. AUC(0-τ) of STX-478  
Timeframe: 12 months
5. Change from baseline in ctDNA levels  
Timeframe: 12 months
6. Changes in circulating markers of glucose metabolism as assessed by changes in circulating glycosylated hemoglobin (HbA1c)  
Timeframe: 12 months
7. Changes in circulating markers of glucose metabolism as assessed by circulating fasting plasma glucose  
Timeframe: 12 months
8. Changes in circulating markers of glucose metabolism as assessed by circulating C-peptide  
Timeframe: 12 months
9. Change in ECOG performance status  
Timeframe: 12 months
10. Disease Control Rate (DCR) per RECIST v1.1, measured as percentage of participants with Complete Response  
Timeframe: 12 months

Sources for outcomes

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

## Eligibility

**Sex**

All

**Age groups**

Adults, Older adults

**Minimum age**

18 Years

**Healthy volunteers**

No

Key Inclusion Criteria:

- Has an advanced or refractory solid tumor malignancy that is metastatic or locally advanced and unresectable (as specified by Cohort)
- Has a new or recent tumor biopsy (collected at screening, if feasible) or will provide an adequate tissue sample prior to screening
- Has a tumor that harbors a documented PI3Kα mutation (cohort specific criterion for cohort-specific mutation types)
- Is ≥18 years of age at the time of signing the ICF
- Has an ECOG performance status score of 0 or 1 at screening
- Has adequate organ function as defined per protocol

Key Exclusion Criteria:

- Has history (within ≤2 years before screening) of a solid tumor or hematological malignancy that is histologically distinct from the cancers being studied
- Has symptomatic brain or spinal metastases
- Has an established diagnosis of uncontrolled diabetes mellitus (defined as HbA1c ≥8% and/or FBG ≥140 mg/dL \[7.7 mmol/L\] and/or requiring or required insulin).
- Has had prior treatment with PI3K/AKT/mTOR inhibitor(s), except in certain circumstances
- Has had treatment with any local or systemic antineoplastic therapy or investigational anticancer agent within 14 days or 4 half-lives, whichever is longer, prior to the initiation of study treatment up to a maximum washout period of 28 days. Endocrine therapy does not require a washout period if the patient is enrolling in a cohort with the same combination endocrine therapy.
- Has toxicities from previous anticancer therapies that have not resolved to baseline levels or CTCAE grade ≤1, with the exception of alopecia and peripheral neuropathy.
- Has had radiotherapy within 14 days before the initiation of study treatment

Sources for eligibility

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

## Sites

- Ellison Clinic at Saint John'sLos Angeles, United StatesRecruiting
- UCSF Medical Center at Mission BaySan Francisco, United StatesRecruiting
- University of Colorado Cancer CenterAurora, United StatesRecruiting
- Yale-New Haven HospitalNew Haven, United StatesCompleted
- Florida Cancer Specialists ORLANDO/DDULake Mary, United StatesCompleted
- Moffitt Cancer CenterTampa, United StatesRecruiting
- Winship Cancer Institute, Emory UniversityAtlanta, United StatesRecruiting
- University of IowaIowa City, United StatesRecruiting
- Louisiana State University Health Sciences CenterNew Orleans, United StatesRecruiting
- Massachusetts General HospitalBoston, United StatesRecruiting
- Dana-Farber Cancer InstituteBoston, United StatesRecruiting
- Barbara Ann Karmanos Cancer InstituteDetroit, United StatesTerminated
- START MidwestGrand Rapids, United StatesRecruiting
- Saint Luke's Cancer InstituteKansas City, United StatesRecruiting
- Washington UniversitySt Louis, United StatesRecruiting
- Memorial Sloan Kettering Cancer CenterNew York, United StatesRecruiting
- UH Cleveland Medical CenterCleveland, United StatesRecruiting
- Stefanie Spielman Comprehensive Breast CenterColumbus, United StatesRecruiting
- Providence Cancer Institute Franz ClinicPortland, United StatesRecruiting
- The West Clinic, PLLC dba West Cancer CenterGermantown, United StatesRecruiting
- Sarah Cannon Research InstituteNashville, United StatesRecruiting
- Mary Crowley Cancer Research CenterDallas, United StatesCompleted
- Texas Oncology-Baylor Charles A. Sammons Cancer CenterDallas, United StatesRecruiting
- University of Texas SouthwesternDallas, United StatesRecruiting
- University of Texas MD Anderson Cancer CenterHouston, United StatesRecruiting

And 40 more, listed on the interactive page.

Sources for sites

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

## References

### Other registry identifiers (5)

- 2023
- 2023-504807-94-00
- 2023-000442-41
- J6M-OX-JSGA
- STX-478-101

Sources for references

Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05768139)

## Related records

### Drugs (11)

- [Abemaciclib](https://trialight.com/data/asset/abemaciclib-602a9f33-bc37-4cf5-8790-5d87472b99d5.md)
- [Anastrozole](https://trialight.com/data/asset/anastrozole-327e05a9-e5b7-41d1-a335-bd8a46453b55.md)
- [Exemestane](https://trialight.com/data/asset/exemestane-367c47e6-e892-496e-bbb5-5b4926a3c31a.md)
- [Fulvestrant](https://trialight.com/data/asset/fulvestrant-c32705f5-1d97-4fd5-a6ee-76fe1d8eba3a.md)
- [Imlunestrant](https://trialight.com/data/asset/imlunestrant-a53f4bdf-2b09-4370-9990-71ac2d706245.md)
- [Letrozole](https://trialight.com/data/asset/letrozole-67319198-7e88-4130-b185-d776c835863c.md)
- [Metformin hydrochloride](https://trialight.com/data/asset/metformin-hydrochloride-10ef84a6-9052-459a-9134-fada726e38d0.md)
- [Palbociclib](https://trialight.com/data/asset/palbociclib-2686787c-5f11-4b65-9a5b-549fcd2af644.md)
- [Ribociclib](https://trialight.com/data/asset/ribociclib-e1583670-a6ef-48c5-8d6a-4d83f85a626d.md)
- [STX-478](https://trialight.com/data/asset/stx-478-be747e6f-d1c8-48a7-a2d8-05107a77ab5f.md)
- [Tamoxifen citrate](https://trialight.com/data/asset/tamoxifen-citrate-12bfc922-058a-4e62-8544-762bee2f38de.md)

### Lead sponsors (1)

- [Eli Lilly and Company](https://trialight.com/data/company/eli-lilly-and-company-9da7efcc-bafe-4b95-b30b-e87a97770db7.md)

### Conditions (9)

- [ADULT syndrome](https://trialight.com/data/condition/adult-syndrome-8aeb5e11-f165-5276-850c-05129a3e72a5.md)
- [Breast cancer](https://trialight.com/data/condition/breast-cancer-8ac10da3-93bd-54c5-a93b-265bc6699689.md) Primary condition
- [Breast disorder](https://trialight.com/data/condition/breast-disorder-c24c48eb-9ec6-54b1-80b7-1e9cec90eba4.md)
- [Breast neoplasm](https://trialight.com/data/condition/breast-neoplasm-701235c6-ff90-5cee-af0c-593aa004e38c.md)
- [Cervical cancer](https://trialight.com/data/condition/cervical-cancer-10fb8f6c-5aac-5281-8f06-7238adeec443.md)
- [Endometrial cancer](https://trialight.com/data/condition/endometrial-cancer-4da2a0bc-7943-502b-a698-cc2beccbed8c.md)
- [Head and neck neoplasm](https://trialight.com/data/condition/head-and-neck-neoplasm-6436d68c-825f-5a7a-bb29-99e9ae9e009a.md)
- [Head and neck squamous cell carcinoma](https://trialight.com/data/condition/head-and-neck-squamous-cell-carcinoma-cbc3ae58-4a6c-52e4-a41b-274051db19fa.md)
- [Ovarian neoplasm](https://trialight.com/data/condition/ovarian-neoplasm-1e9924ea-041c-5daa-b6c4-a97ec4fabeda.md)

### Targets (56)

- [CCND1](https://trialight.com/data/target/ccnd1-5f6a6270-9aec-5f1d-9fd9-19c16cfaf816.md)
- [CDK4](https://trialight.com/data/target/cdk4-7911e947-47b0-5d57-b5c3-76425934201f.md)
- [CDK6](https://trialight.com/data/target/cdk6-a48645cb-6daf-5fe9-a635-f8d00b55b425.md)
- [COXFA4](https://trialight.com/data/target/coxfa4-7d75e29a-decc-5e87-b2d6-1ac11b00ba7c.md)
- [COXFA4L2](https://trialight.com/data/target/coxfa4l2-74460d10-783f-506a-826c-ada6b04395f0.md)
- [CYP19A1](https://trialight.com/data/target/cyp19a1-9682b33b-ed66-55a7-8155-bf00584059c7.md)
- [ESR1](https://trialight.com/data/target/esr1-e58c882c-75fc-5507-bf76-2d7a172c0a28.md)
- [GPD2](https://trialight.com/data/target/gpd2-4ef823da-c09f-5600-bf22-d4201ee4de3c.md)
- [MT-ND1](https://trialight.com/data/target/mt-nd1-da56bfa6-9109-5230-9fab-1feb175e18e8.md)
- [MT-ND2](https://trialight.com/data/target/mt-nd2-05bc86a7-c29a-59a5-933e-abc1f52bf9cd.md)
- [MT-ND3](https://trialight.com/data/target/mt-nd3-65ff2fc6-2cee-522f-b556-952089a8ccbb.md)
- [MT-ND4](https://trialight.com/data/target/mt-nd4-6174af49-88e7-5f62-b9eb-b1d21888b5dd.md)
- [MT-ND4L](https://trialight.com/data/target/mt-nd4l-bd147784-576b-5e87-8df0-1b70bcbb0d8f.md)
- [MT-ND5](https://trialight.com/data/target/mt-nd5-78e4779d-c75a-5b40-9e0d-21b79ac1230f.md)
- [MT-ND6](https://trialight.com/data/target/mt-nd6-351e625f-2043-541e-b898-671764f99a8e.md)
- [NDUFA1](https://trialight.com/data/target/ndufa1-cd940f95-7d60-5194-8f72-29194a2a5e02.md)
- [NDUFA10](https://trialight.com/data/target/ndufa10-1a66e96a-a0ea-538c-aeda-78dc367fa80e.md)
- [NDUFA11](https://trialight.com/data/target/ndufa11-1ab92f5e-4b24-5365-8e25-3bf9ca99a0ff.md)
- [NDUFA12](https://trialight.com/data/target/ndufa12-f8b18d37-f6ac-50db-98db-4994cb7ef1ee.md)
- [NDUFA13](https://trialight.com/data/target/ndufa13-87ddc7f8-fee4-57e0-b37b-0ab5701328bc.md)

---

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