Uterine leiomyosarcomas (ULMS) are a rare cause of uterine malignancy. Due to their aggressive nature, resistance to standard therapy and high rates of recurrence, they are associated with a very poor prognosis, irrespective of their stage at diagnosis. A 68-year-old female, Chinese patient was diagnosed with Stage IVB uterine leiomyosarcoma with lung metastasis. Disease progression occurred after fourth-line treatment and the patient was commenced on pembrolizumab and temozolomide combination therapy. At the time of writing, our patient has experienced partial response to treatment with minimal adverse effects at cycle 7 of Pembrolizumab in combination with Temozolomide.