Your medical history will be reviewed to confirm that you have a diagnosis of metastatic (cancer that has spread to other parts of the body) or locally advanced (cancer that has grown beyond its original site but has not spread to distant parts of the body) disease that cannot be removed by surgery.

Your tumor tissue will be examined under a microscope to confirm the diagnosis of neuroendocrine tumor (a type of cancer that develops from cells that release hormones into the blood), neuroendocrine carcinoma, or other solid tumor types.

Imaging scans will be reviewed to confirm that your disease has grown or progressed based on RECIST version 1.1 (a standard method used to measure tumor size and response to treatment).

You will undergo somatostatin receptor imaging (a special scan that shows whether your tumor has specific proteins called somatostatin receptors on its surface) to confirm that your tumor expresses these receptors.

The imaging will also confirm that you have at least one tumor location that can be measured according to RECIST version 1.1 criteria.

You will be assigned to receive CRN09682, which is an experimental medication being tested in this study.

The study has two phases: a Dose Escalation Phase and a Dose Expansion Phase.

If you enter during the Dose Escalation Phase, you will receive a specific dose level of CRN09682 that is being tested for safety. Different groups of participants receive different dose levels.

If you enter during the Dose Expansion Phase, you will receive the dose of CRN09682 that was selected based on the results from the Dose Escalation Phase.

You will receive CRN09682 as an intravenous infusion (given directly into a vein through a needle or tube).

The medication is prepared as a solution for injection.

The specific dosage, frequency of administration, and duration of treatment will be determined based on which phase of the study you are in and how you respond to the medication.

Your healthcare team will monitor you during each infusion.

Throughout the study, you will be monitored for any adverse events (unwanted or harmful effects that may occur during treatment).

If you are in the Dose Escalation Phase, you will be closely watched for dose-limiting toxicities (serious side effects that may require stopping or reducing the dose of medication).

Blood samples will be collected at specific times to measure the levels of CRN09682 and MMAE (a component of the study drug) in your blood. This is called pharmacokinetic testing and helps understand how your body processes the medication.

Blood samples will be taken before each dose and at the end of infusion to measure drug concentrations.

Any side effects that lead to interruption or stopping of the study medication will be recorded.

You will have regular imaging scans to assess how your tumor is responding to the treatment.

The scans will be evaluated using RECIST version 1.1 criteria to determine if your tumor has shrunk, stayed the same size, or grown.

The possible responses include: complete response (all tumors have disappeared), partial response (tumors have shrunk by at least 30%), stable disease (tumors have neither grown significantly nor shrunk significantly), or progressive disease (tumors have grown).

Additional somatostatin receptor imaging may be performed during the Dose Expansion Phase to assess changes in receptor expression.

The time from when your tumor responds to treatment until it grows again will be measured. This is called duration of response.

The time from when you start treatment until your disease progresses will also be measured. This is called progression-free survival.

You will continue to receive CRN09682 as long as the treatment is helping you and you are not experiencing unacceptable side effects.

Regular visits will be scheduled to monitor your health, assess side effects, and evaluate how your tumor is responding.

If your disease progresses or if you experience side effects that cannot be managed, treatment may be stopped.

Your participation in the treatment phase will continue according to the study protocol and your individual response to therapy.