Study of THEO-260 for Patients with High-Grade Serous or Endometrioid Ovarian Cancer

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What is this study about?

This is a clinical trial studying high grade serous or endometrioid ovarian cancer, which are aggressive types of cancer that can affect the ovaries, fallopian tubes, or the lining of the abdominal cavity (peritoneum). The study will test a medication called THEO-260 in patients whose cancer has become resistant to platinum-based chemotherapy (meaning the cancer has returned or continued growing within 6 months after receiving platinum treatment) or who cannot tolerate standard treatments.

The purpose of this study is to determine the safety, appropriate dosage, and preliminary effectiveness of THEO-260 for treating these types of ovarian cancer. The study is divided into two parts: the first part focuses on finding a safe dose and evaluating side effects, while the second part examines whether the treatment is effective against the cancer at the recommended dose.

During the trial, participants will receive THEO-260 and undergo various assessments including blood tests, imaging scans (CT or MRI), and quality of life questionnaires. The researchers will monitor for side effects, including potential immune-related adverse events (side effects related to the immune system) and cytokine release syndrome (a condition that can cause fever and other symptoms when certain treatments activate the immune system).

1 Initial Screening and Preparation

After joining the study, you will undergo screening to confirm your eligibility. This includes verification of your high grade serous or endometrioid ovarian cancer diagnosis.

Medical tests will be performed to ensure you have adequate organ function and meet other health requirements. Your current performance status will be evaluated using the ECOG scale (a measure of how well you can perform daily activities).

You will need to have measurable disease that can be tracked on scans according to standard measurement criteria (RECIST).

2 Treatment Phase – THEO-260 Administration

You will receive THEO-260, an investigational medication given by infusion (through a vein).

If you are in Part A of the study (Phase I), different dose levels will be tested to determine the safest and most effective dose.

If you are in Part B of the study (Phase IIa), you will receive the recommended dose determined from Part A.

The treatment schedule and total duration will be determined by your doctor based on the study protocol and your response to treatment.

3 Monitoring During Treatment

Throughout the treatment period, you will have regular check-ups to monitor your health and assess how well the treatment is working.

These assessments include blood tests, physical examinations, vital sign measurements, ECGs (heart tests), and evaluation of your performance status.

Samples will be collected to measure the amount of THEO-260 in your blood (pharmacokinetics) and to check for the presence of THEO-260 in your buccal (cheek), urine, and stool samples.

Blood tests will also be performed to monitor for cytokine release (immune system proteins that can cause inflammation) following administration of THEO-260.

4 Tumor Response Assessment

Your cancer’s response to treatment will be regularly evaluated using imaging scans (CT or MRI).

These scans will measure any changes in tumor size according to standardized criteria (RECIST v1.1).

Additionally, your CA-125 levels (a blood marker commonly elevated in ovarian cancer) will be monitored throughout the study.

You will complete quality of life questionnaires to assess how the treatment is affecting your daily functioning and wellbeing.

5 Side Effect Monitoring

Throughout the study, you will be closely monitored for any side effects or adverse events.

Special attention will be paid to immune-related adverse events (side effects related to the immune system) and cytokine release syndrome (a condition that can cause fever and other symptoms).

Any side effects will be graded according to standardized criteria (NCI CTCAE v5.0) to determine their severity.

Your doctor will manage any side effects that occur during the study.

6 Follow-up Period

After completing the treatment phase, you will enter a follow-up period to continue monitoring your health and disease status.

Follow-up visits will include physical examinations, laboratory tests, and imaging scans to assess the long-term effects of the treatment and monitor your cancer.

The total duration of the follow-up period will be determined by your doctor based on the study protocol.

Who Can Join the Study?

You must have high grade serous or endometrioid cancer of the ovary, fallopian tube, or primary peritoneum (lining of the abdominal cavity) confirmed by tissue examination
You must be willing to provide written consent to participate and follow study requirements
You must be female and at least 18 years old
You must have a life expectancy of more than 3 months
You must have adequate blood cell counts and organ function (specific blood test values will be checked)
If you can become pregnant, you must be willing to use effective birth control, or be post-menopausal, surgically sterile, or abstinent
You must have an ECOG performance status of 0 or 1 (able to perform most daily activities with minimal or no assistance)
You must have measurable disease according to RECIST criteria (a standard way to measure tumors on scans)
For Phase I: You must have cancer that is resistant to platinum treatment (came back within 6 months after platinum treatment), or that didn’t respond to initial platinum treatment, or you cannot tolerate standard treatments
For Phase IIa: You must have advanced platinum-resistant disease (cancer that returned within 6 months after platinum treatment) or you’re progressing on standard treatment, or cannot tolerate standard treatments

Who Cannot Join the Study?

You are pregnant or breastfeeding.
You have previously received a combination treatment of ATR and PARP inhibitors (specific types of cancer drugs).
You have active, uncontrolled brain metastases (cancer that has spread to the brain).
You have received radiotherapy (radiation treatment) within 14 days before starting the study.
You have had major surgery within 28 days before starting the study.
You have significant heart problems, including heart attack within 6 months, heart failure, or abnormal heart rhythms.
You have uncontrolled high blood pressure.
You have active, uncontrolled infections.
You have any other serious medical condition that could affect your participation in the study.
You are currently participating in another clinical trial with an investigational drug.
You have a known allergy or sensitivity to the study drug or its components.
You have severe liver or kidney problems that could affect how your body processes the medication.

Where you can join this trial?

Verified and Recommended Sites

No sites found in this category

Verified Sites

Site Name	City	Country	Status
Hospital Universitario Hm Sanchinarro	Madrid	Spain
Hospital Universitario De Navarra	Pamplona	Spain

Other Sites

Site Name	City	Country	Status
Hospital Universitario 12 De Octubre	Madrid	Spain
Icpiffuy Coaafk Dzaakdmadamhynzoy	L'hospitalet De Llobregat	Spain

Trial status

Country	Status	Recruitment Start
Spain	Recruiting	01.10.2025

Trial locations

THEO-260 is an investigational medication being studied for the treatment of high grade serous or endometrioid ovarian cancer. The trial is exploring different doses to determine the safest and most effective dose for patients with these types of ovarian cancer. The study will evaluate how well the body tolerates this medication and whether it shows promising effects against ovarian tumors.

Investigated diseases:

Ovarian cancer

High grade serous ovarian cancer – A rapidly growing form of ovarian cancer that develops in the tissue covering the ovary. It is characterized by the formation of abnormal cells that multiply quickly and can spread to nearby tissues. The disease typically progresses without noticeable symptoms in early stages, with symptoms becoming apparent as the tumor grows and puts pressure on surrounding organs. These symptoms may include abdominal bloating, pelvic pain, difficulty eating, and frequent urination.

Endometrioid ovarian cancer – A type of epithelial ovarian cancer that resembles the tissue lining the uterus (endometrium). It develops when cells similar to those in the endometrium begin growing abnormally in the ovaries. This cancer typically grows more slowly than other types of ovarian cancer. As it progresses, it can cause symptoms such as pelvic pain, abnormal vaginal bleeding, and a feeling of fullness in the abdomen. Endometrioid ovarian cancer is often associated with endometriosis, a condition where endometrial tissue grows outside the uterus.

Trial ID:

2024-511236-27-00

Protocol code:

THEO-260-001

NCT ID:

NCT06618235

Trial Phase:

Phase I and Phase II (Integrated) – First administration to humans

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Study of THEO-260 for Patients with High-Grade Serous or Endometrioid Ovarian Cancer

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