A new global study has been launched to help gain a deeper understanding of ROS1 gene fusions, a rare cause of some types of cancers, including ovarian. The initiative is a joint effort by the Addario Lung Cancer Medical Institute (ALCMI), along with Champions Oncology and the ROS1ders, a group of patients and caregivers dealing with ROS1-positive cancers. Patients with this rare tumor type can now enroll in the study to help researchers develop patient-derived xenografts (PDX) models for ROS1 fusion cancers. PDX models help researchers study cancer. They are created by implanting a piece of a patient's tumor into a mouse with a deficient immune system. These rodent “hosts” allow the tumor to grow while maintaining features similar to the patient's original tumor. This is useful to study tumor growth, therapy response, and acquired resistance to therapies. The purpose of the ALCMI-006 ROS1 PDX study is to make at least 24 PDX models for ROS1-positive cancers, which can then be used for research purposes. Participants in the study receive no immediate benefit, but down the road, the goal is to use these models to develop new and more effective therapies against this cancer subset. ROS1 rearrangements occur in 1 to 3 percent of ovarian, lung, and gastric cancers, as well as melanoma and other cancers. ROS1 is an enzyme coded by the ROS1 gene. A gene fusion occurs when a gene unnaturally breaks off and fuses with another gene, forming a hybrid gene that can lead to cancer initiation and growth. The study is the latest effort of the Global ROS1 Initiative, which was created to improve outcomes for this type of cancer. ROS1-positive patients who meet eligibility criteria may enroll and contribute with viable tumor tissue to develop the PDX models.