Exceptional Response to Everolimus in a Patient with Metastatic Castrate-Resistant Prostate Cancer Harboring a PTEN Inactivating Mutation

Small cell neuroendocrine prostate cancer with adenocarcinoma components-case report and literature review

Background

Small cell neuroendocrine prostate cancer (SCNC) is a rare aggressive type of neuroendocrine prostate cancer (NEPC) characterized by aggressive clinical course and lack of response to hormone therapy.

Case Description

We present a case report of a 60-year-old man diagnosed with a histologically confirmed primary metastatic (bone, lymph nodes and visceral) SCNC with small components of an adenocarcinoma with clinical symptoms mimicking an acute prostatitis. Of note, serum based neuroendocrine markers (carcinoembryonic antigen, chromogranin A) were negative and the patient had a prostate-specific antigen (PSA) elevation. Genetic testing of tumor tissue revealed breast cancer gene 2 (BRCA2) copy number loss and a retinoblastoma gene (RB1) mutation reflecting again the aggressiveness of the disease. Germline testing for the BRCA2 copy number loss was unremarkable. After 6 cycles of carboplatin and etoposide in combination with androgen deprivation therapy (ADT) the Eastern Cooperative Oncology Group (ECOG) performance status has improved from 3 to 0, in addition the patient was free of pain. In line with clinical improvement, both prostate-specific membrane antigen (PSMA) and fluorodeoxyglucose positron emission tomography-computed tomography (FDG PET-CT) revealed a significant reduction of metastatic load. Currently, the patient is treated with ADT plus apalutamide.

Conclusions

We demonstrate for the first time a case of a primary metastatic SCNC with adenocarcinoma components successfully treated by the combination of platinum-based chemotherapy plus hormonal therapy. In addition, we provide a literature overview on management of SCNC as there is no standard treatment established for this disease.

Exploring the role of PI3K/AKT/mTOR inhibitors in hormone-related cancers: A focus on breast and prostate cancer

Breast cancer (BC) and prostate cancer (PC) are at the top of the list when it comes to the most common types of cancers worldwide. The phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling pathway is important, in that it strongly influences the development and progression of these tumors. Previous studies have emphasized the key role of inhibitors of the PIK3/AKT/mTOR signaling pathway in the treatment of BC and PC, and it remains to be a crucial method of treatment. In this review, the inhibitors of these signaling pathways are compared, as well as their effectiveness in therapy and potential as therapeutic agents. The use of these inhibitors as polytherapy is evaluated, especially with the use of hormonal therapy, which has shown promising results.

The PTEN Conundrum: How to Target PTEN-Deficient Prostate Cancer

Loss of the tumor suppressor phosphatase and tensin homologue deleted on chromosome 10 (PTEN), which negatively regulates the PI3K-AKT-mTOR pathway, is strongly linked to advanced prostate cancer progression and poor clinical outcome. Accordingly, several therapeutic approaches are currently being explored to combat PTEN-deficient tumors. These include classical inhibition of the PI3K-AKT-mTOR signaling network, as well as new approaches that restore PTEN function, or target PTEN regulation of chromosome stability, DNA damage repair and the tumor microenvironment. While targeting PTEN-deficient prostate cancer remains a clinical challenge, new advances in the field of precision medicine indicate that PTEN loss provides a valuable biomarker to stratify prostate cancer patients for treatments, which may improve overall outcome. Here, we discuss the clinical implications of PTEN loss in the management of prostate cancer and review recent therapeutic advances in targeting PTEN-deficient prostate cancer. Deepening our understanding of how PTEN loss contributes to prostate cancer growth and therapeutic resistance will inform the design of future clinical studies and precision-medicine strategies that will ultimately improve patient care.