- Patients with leiomyosarcoma must have tumors with intact Rb as documented by protein expression by IHC for study entry. Patients without sufficient archival tissue for testing will not be eligible. Please see Section 9.0 for further details on testing and interpretation of results. In the event that a patient has prior sequencing information (i.e. through commercial testing) suggestive of intact Rb, the patient may be included into the study on a case by case basis as determined by the principle investigators. The patient will still be required to submit tissue for Rb determination by IHC, but will not need to wait for these results for study entry.