Does the Rechallenge with Another CDK 4/6 Inhibitor in Breast Cancer Work? A Case Report and Literature Review.

Cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors and endocrine therapy are the gold standards for systemic therapy for patients with hormone-positive (HR+)/human epidermal growth factor receptor-2-negative (HER2-) metastatic breast cancer. Following progression, no prospective randomized data exist to help guide second-line treatment. Moreover, there is a scarcity of data on rechallenge treatment strategies with another CDK4/6 inhibitor after prior limiting toxicity. We report a real-world experience of rechallenging with abemaciclib after the prior reaction of grade 4 liver toxicity to ribociclib, with high transaminases values of more than 27 times the upper limit of normal (ULN) and unexpected grade 3 neutropenia and diarrhea after a few months of abemaciclib. After two years of treatment, the patient had stable oncological disease, with normal complete blood count, hepatic enzymes, and a very good performance status. We believe that our clinical case, along with others gathered from all around the world, will help with the consolidation of an unmet clinical need to readjust the treatment after experiencing toxicity to CDK4/6 inhibitors.

Extremely Rare Type of Breast Cancer-Dedifferentiated Breast Liposarcoma-Diagnosis and Treatment.

Primary liposarcoma of the breast is an uncommon soft tissue malignant tumor, comprising only 0.003% of all malignant breast tumors. The main differential diagnosis of this mass consists of malignant phyllodes tumor and metaplastic breast carcinoma. The objective of this paper is to report a case of dedifferentiated breast liposarcoma, therapeutic approach and outcome. We present a case of a 79-year-old woman complaining of a large mass in her left breast which had increased in size over the last 6 months. Physical examination revealed an enlarged left breast, and a total body CT scan showed a large tumor in contact with the musculature of the anterior thoracic wall, with no metastatic lesions. The histopathology report of a fine needle biopsy described a high-grade sarcoma. The Oncological Tumor Board recommended neoadjuvant radiotherapy sessions and reevaluation by MRI and CT scans. The patient underwent radical mastectomy with latissimus dorsi myo-cutaneous flap reconstruction. The final histopathology diagnosis was a grade 3 dedifferentiated liposarcoma (FNCLCC), with certain response to radiotherapy and positive MDM2, CDK4 markers. The postoperative period was uneventful; 12 months after surgery, the follow-up CT scan showed multiple pulmonary lesions with metastatic characteristics. Liposarcoma is a very rare type of breast cancer, and the most important treatment for breast sarcoma is surgery, the role of axillary lymph node removal, chemotherapy and radiotherapy still being controversial. Considering such cases are scarce and the development of surgical guidelines is difficult, reporting any new case is crucial.