**Study Purpose**: This research looks at whether a combination of three medications, *avutometinib*, *defactinib*, and *letrozole*, helps treat *low-grade serous ovarian cancer* (LGSOC). The safety of these drugs will also be checked. **Eligibility**: Women aged 18 or older with confirmed LGSOC can join. Participants need to have measurable disease, which means their tumors can be measured with imaging tests like CT or MRI. They should have good heart health, as shown by tests like an echocardiogram. HIV patients with a low viral load and those with treated hepatitis can join. Women of childbearing age must use birth control during the study. **Key Points**: - The study is open to women with specific health conditions and requires regular health check-ups. - Participants should not have had major surgery recently or systemic anti-cancer therapy for LGSOC. - Certain medications, foods, and supplements that might interfere with the study drugs should be avoided. This study may provide new treatment options for women with LGSOC but comes with specific requirements and restrictions.