Evaluation of the Preclinical Efficacy of Lurbinectedin in Malignant Pleural Mesothelioma

Ecteinascidin synthetic analogues: a new class of selective inhibitors of transcription, exerting immunogenic cell death in refractory malignant pleural mesothelioma

BACKGROUND

Malignant pleural mesothelioma (MPM) is a highly chemo-refractory and immune-evasive tumor that presents a median overall survival of 12-14 months when treated with chemotherapy and immunotherapy. New anti-tumor therapies as well as the concomitant reactivation of immune destruction are urgently needed to treat patients with this tumor. The aim of this work is to investigate the potential effect of ecteinascidin derivatives as lurbinectedin as new first-line treatment option in MPM, alone and in combination with immunotherapy.

METHODS

The antitumor activity of ecteinascidin synthetic analogues: lurbinectedin, ecubectedin and PM54 was evaluated in an array of patient-derived MPM cells in terms of cell proliferation, cell cycle, apoptosis, DNA damage and repair. Immunoblot was used to assess the cGAS/STING pathway. ELISA and flow cytometry-based assays were used to evaluate immunogenic cell death parameters and the effect on the immunophenotype in autologous peripheral blood monocyte-MPM cells co-cultures. Patient-derived xenografts (PDX) in humanized mice were used to evaluate the efficacy of ecteinascidins in vivo.

RESULTS

Lurbinectedin, ecubectedin, and PM54 were effective in reducing cell proliferation and migration, as well as inducing S-phase cell cycle arrest and DNA damage in malignant pleural mesothelioma cells. These effects were more pronounced compared to the standard first-line treatment (platinum-based plus pemetrexed). Mechanistically, the drugs downregulated DNA repair genes, activated the cGAS/STING pathway, and promoted the release of pro-inflammatory cytokines. They also induced immunogenic cell death of mesothelioma cells, enhancing the activation of anti-tumor CD8+T-cells and natural killer cells while reducing tumor-tolerant T-regulatory cells and myeloid-derived suppressor cells in ex vivo co-cultures. These promising results were also observed in humanized patient-derived xenograft models, where the drugs were effective in reducing tumor growth and increasing the ratio anti-tumor/pro-tumor infiltrating immune populations, either alone or combined with the anti-PD-1L atezolizumab.

CONCLUSIONS

Collectively, these findings reveal a previously unknown mechanism of action of ecteinascidins that merits further investigation for potential clinical applications in the treatment of MPM, as new first line treatment in monotherapy or in association with immunotherapy.

Pleural mesothelioma: a snapshot of emerging drug targets and opportunities for non-surgical therapeutic advancement

INTRODUCTION

Pleural mesothelioma is a rare and aggressive cancer originating in the pleura, with a devastating prognosis and limited treatment options. There have been significant advancements in the management of this disease in recent years. Since 2021, nivolumab and ipilimumab immune checkpoint inhibitors have become the new standard of care for first-line treatment of pleural mesothelioma.

AREAS COVERED

While a combination of chemotherapy and immune checkpoint inhibitors appears to be the next step, targeted therapies are emerging thanks to our understanding of the oncogenesis of pleural mesothelioma. Moreover, several new strategies are currently being investigated, including viral therapy, antibody-drug conjugates, and even cell therapies with CAR-T cells or dendritic cells. In this review, we will explore the various future opportunities that could potentially transform patients' lives in light of the clinical trials that have been conducted.

EXPERT OPINION

Future clinical studies aim to rebiopsy patients after disease progression to identify new molecular alterations and to be associated with ancillary studies, guiding subsequent therapy decisions. Predicting and investigating treatment resistance mechanisms will lead to innovative approaches and improved treatment outcomes.

Trabectedin and lurbinectedin: Mechanisms of action, clinical impact, and future perspectives in uterine and soft tissue sarcoma, ovarian carcinoma, and endometrial carcinoma

The ecteinascidins trabectedin and lurbinectedin are very interesting antineoplastic agents, with a favorable toxicity profile and peculiar mechanisms of action. These drugs form adducts in the minor groove of DNA, which produce single-strand breaks (SSBs) and double-strand breaks (DSBs) and trigger a series of events resulting in cell cycle arrest and apoptosis. Moreover, the ecteinascidins interact with the tumor microenvironment, reduce the number of tumor-associated macrophages, and inhibit the secretion of cytokines and chemokines. Trabectedin has been approved by the Federal Drug Administration (FDA) for patients with unresectable or metastatic liposarcoma or leiomyosarcoma who received a prior anthracycline-based regimen. Moreover, trabectedin in combination with pegylated liposomal doxorubicin (PLD) has been approved in the European Union for the treatment of platinum-sensitive recurrent ovarian cancer. Lurbinectedin has been approved by the FDA for patients with metastatic small cell lung cancer with disease progression on or after platinum-based chemotherapy. The review assesses in vitro and in vivo experimental studies on the antineoplastic effects of both ecteinascidins as well as the clinical trials on the activity of trabectedin in uterine sarcoma and ovarian carcinoma and of lurbinectedin in ovarian carcinoma and endometrial carcinoma.

A Glimpse in the Future of Malignant Mesothelioma Treatment

Malignant mesothelioma (MMe) is a rare neoplasm with few therapeutic options available. The landscape of effective therapy for this disease remained unchanged in the last two decades. Recently, however, the introduction of Immune Checkpoint Inhibitors (ICIs) led to small, but nevertheless, promising improvements. However, many efforts are still needed to radically improve the prognosis of MMe. In this review, we analyze all those therapeutic strategies for MMe that are still in a preclinical or early clinical phase of development. In particular, we focus on novel antiangiogenic drugs and their possible combination with immunotherapy. Furthermore, we describe also more complex strategies such as microRNA-loaded vectors, oncolytic viruses, and engineered lymphocytes.