Olaparib Combined With Dacomitinib in Osimertinib-Resistant Brain and Leptomeningeal Metastases From Non-Small Cell Lung Cancer: A Case Report and Systematic Review

PARP1 promotes EGFR-TKI drug-resistance via PI3K/AKT pathway in non-small-cell lung cancer

PURPOSE

Tyrosine kinase inhibitor (TKI) resistance is the main type of drug resistance in lung cancer patients with epidermal growth factor receptor (EGFR) mutations, but its underlying mechanism remains unclear. The purpose of this work was to investigate the mechanism by which PARP1 regulates EGFR-TKI resistance to identify potential targets for combating drug resistance.

METHODS

The GEO databases, TCGA databases, western blot and qPCR studies were used to investigate the expression of PARP1 in lung cancer cells and tissues and its correlation with the prognosis of lung cancer. The expression of PARP1 in lung cancer TKI resistant cell PC9-ER and TKI sensitive cell PC9 was analyzed by qPCR and western blot. After knocking down of PARP1, CCK-8 assays, colony formation, flow cytometry were used to investigate its impact on erlotinib sensitivity, cell survival, cell cycle, and apoptosis. RNA-seq was used to investigate the mechanism by which PARP1 participates in EGFR-TKI resistance, and the results were validated in vitro and in vivo studies.

RESULTS

PARP1 was highly expressed in both lung cancer tissues and cells. Subsequently, increased PARP1 expression was observed in PC9-ER compared with its parental cell line. Knockdown of PARP1 increased erlotinib sensitivity, promoted cell apoptosis, and suppressed cell growth. RNA-seq and previous studies have shown that the PI3K/AKT/mTOR/P70S6K pathway is involved in PARP1-mediated TKI resistance, and these results were confirmed by Western blot in vitro and in vivo.

CONCLUSION

PARP1 may serve as a potential therapeutic target for reversing EGFR-TKI resistance in NSCLC via the PI3K/AKT/mTOR/P70S6K pathway.

Clinical translation for targeting DNA damage repair in non-small cell lung cancer: a review

Despite significant advancements in screening, diagnosis, and treatment of non-small cell lung cancer (NSCLC), it remains the primary cause of cancer-related deaths globally. DNA damage is caused by the exposure to exogenous and endogenous factors and the correct functioning of DNA damage repair (DDR) is essential to maintain of normal cell circulation. The presence of genomic instability, which results from defective DDR, is a critical characteristic of cancer. The changes promote the accumulation of mutations, which are implicated in cancer cells, but these may be exploited for anti-cancer therapies. NSCLC has a distinct genomic profile compared to other tumors, making precision medicine essential for targeting actionable gene mutations. Although various treatment options for NSCLC exist including chemotherapy, targeted therapy, and immunotherapy, drug resistance inevitably arises. The identification of deleterious DDR mutations in 49.6% of NSCLC patients has led to the development of novel target therapies that have the potential to improve patient outcomes. Synthetic lethal treatment using poly (ADP-ribose) polymerase (PARP) inhibitors is a breakthrough in biomarker-driven therapy. Additionally, promising new compounds targeting DDR, such as ATR, CHK1, CHK2, DNA-PK, and WEE1, had demonstrated great potential for tumor selectivity. In this review, we provide an overview of DDR pathways and discuss the clinical translation of DDR inhibitors in NSCLC, including their application as single agents or in combination with chemotherapy, radiotherapy, and immunotherapy.

Combination of Osimertinib and Olaparib Therapy to Treat Non-Small Cell Lung Cancer and High-Grade Serous Ovarian Carcinoma: A Case Report

We present the case of a 75-year-old female with simultaneous EGFR-mutated stage IV lung cancer and advanced BRCA2-mutated ovarian cancer, treated with a unique regimen. In this case report, the patient was treated with alternating months of osimertinib and olaparib to control her lung and ovarian cancers, respectively. When both diseases showed progression, the patient underwent a trial of concurrent therapy with both drugs, yet this was discontinued due to patient-reported adverse side effects. Combination targeted drug therapy may be required to treat complex diagnoses such as dual malignancies. However, combination drug therapy consisting of osimertinib and olaparib has not previously been explored. This case report represents the first to demonstrate osimertinib and olaparib combination therapy as a unique treatment regimen for concurrent lung and ovarian cancers. These two drugs can either be given in an alternating way or given together, short-term, with a higher but tolerable toxicity profile.

Leptomeningeal Metastasis from Non-Small Cell Lung Cancer and Current Landscape of Treatments

Leptomeningeal metastasis (LM), also known as leptomeningeal carcinomatosis (LC), is a devastating complication of metastatic cancer that occurs when neoplastic cells invade the meningeal space. Diagnosis of LM remains challenging given the heterogeneous signs and symptoms at presentation and requires thorough neurological examination, cerebrospinal fluid (CSF) analysis, and MRI of the brain and spine with gadolinium. Detecting neoplastic cells in the CSF is the gold standard for diagnosing leptomeningeal metastases; however, it has low sensitivity and may require multiple CSF samples. New emerging technologies, such as liquid biopsy of CSF, have increased sensitivity and specificity for detecting circulating tumor cells in CSF. The management of LM in patients with NSCLC requires an individualized multidisciplinary approach. Treatment options include surgery for ventricular shunt placement, radiation therapy to bulky or symptomatic disease sites, systemic or intrathecal chemotherapy, molecularly targeted agents, and, more recently, immunotherapy. Targeting actionable mutations in LM from NSCLC, such as EGFR tyrosine kinase inhibitors or anaplastic lymphoma kinase gene rearrangement inhibitors, has shown encouraging results in terms of disease control and survival. Although there are limited data regarding the use of immunotherapy in LM, immunotherapy has produced promising results in several case reports. In this review, we focused on the epidemiology, pathophysiology, clinical presentation, diagnosis, and current treatment strategies, with a special emphasis on novel agents, including targeted therapies and immunotherapy of LM in patients with NSCLC.