Study Overview: This research study is testing new medications, trastuzumab and pertuzumab, added to usual chemotherapy (paclitaxel and carboplatin) for a type of cancer called HER2 positive endometrial serous carcinoma or carcinosarcoma. HER2 positive means the cancer cells have a higher number of specific receptors that make them grow. Trastuzumab and pertuzumab are special drugs called monoclonal antibodies, which block these receptors and help the immune system destroy the cancer cells. Hyaluronidase helps these drugs stay in the body longer and allows them to be given under the skin, making treatment quicker.

• This study may last up to 3 years with regular check-ups and involves blood and urine tests.
• Participants will have an equal chance of receiving one of three different treatment plans.
• It's important to consider possible side effects, like fatigue or rashes, and discuss them with your doctor.

This study is only for adults with specific types of endometrial cancer that are HER2 positive. If you have questions or need more information, please talk to your healthcare provider. Participation in any clinical study is voluntary and should be discussed thoroughly with your medical team.