Review of the management of relapsed small-cell lung cancer with amrubicin hydrochloride

Orphan Drugs in Development for the Treatment of Small-Cell Lung Cancer: Emerging Data on Lurbinectedin

Lung cancer is the leading cause of death of all cancer entities and small-cell lung cancer (SCLC) is the most malignant subtype. Despite good initial response to chemotherapy, many patients relapse early and success of second line treatment remains poor. For years, no relevant improvement of second line treatment has been achieved in the field of SCLC. Lurbinectedin, a novel RNA-polymerase II inhibitor has shown promising results in pretreated SCLC patients as single agent and in combination with other chemotherapeutic drugs leading to an orphan drug designation from the FDA. This article reviews the current data on this emerging substance and its impact on the treatment of SCLC.

SCLC-State of the Art and What Does the Future Have in Store?

Worldwide, the total number of diagnosed lung cancer cases amounts to 1.8 million every year. Small-cell lung cancer (SCLC) accounts for about 15% to 17% of all diagnosed lung cancers. Despite all progress made in the field of non-small-cell lung cancer, the prognosis and therapeutic options in SCLC are still limited. The resistance of SCLC to conventional therapy as well as its high recurrence rate can be attributed to the heterogeneous genetic structure of SCLC; however, a targeted therapy approach to SCLC may build on this very heterogeneous genetic structure. SCLC is by now a well-characterized cancer with various genetic alterations; for example, mutations in tumor suppressor genes TP53 and RB1, alterations in chromosome 3p, JAK2, FGFR1, and MYC genes were discovered. Based on these findings, various treatment options (eg, aurora kinase inhibitors, PARP inhibition, immune checkpoint inhibition and vaccine therapy) are currently evaluated with the goal of determining their clinical effectiveness. In this article, we review the existing knowledge of SCLC genetics and the current treatment standards and highlight new approaches of immunotherapy and other targeted therapies, which may yield new treatment options and improve the outcome of patients with SCLC.

Chemotherapy advances in small-cell lung cancer

Although chemotherapeutic advances have recently been heralded in lung adenocarcinomas, such success with small-cell lung cancer (SCLC) has been ominously absent. Indeed, the dismal outlook of this disease is exemplified by the failure of any significant advances in first line therapy since the introduction of the current standard platinum-etoposide doublet over 30 years ago. Moreover, such sluggish progress is compounded by the dearth of FDA-approved agents for patients with relapsed disease. However, over the past decade, novel formulations of drug classes commonly used in SCLC (e.g. topoisomerase inhibitors, anthracyclines, alkylating and platinum agents) are emerging as potential alternatives that could effectively add to the armamentarium of agents currently at our disposal. This review is introduced with an overview on the historical development of chemotherapeutic regimens used in this disease and followed by the recent encouraging advances witnessed in clinical trials with drugs such as amrubicin and belotecan which are forging new horizons for future treatment algorithms.

Amrubicin: potential in combination with cisplatin or carboplatin to treat small-cell lung cancer

Small-cell lung cancer (SCLC) is the most aggressive form of lung cancer characterized by early metastasis and high mortality. In recent years, monotherapy and combination therapy of amrubicin with cisplatin or carboplatin has been actively studied and shown promise for the treatment of extensive disease SCLC (ED-SCLC). In this article, we summarize clinical trials of both monotherapy and combination therapy with amrubicin conducted in Japan, the USA, and the European Union. The results suggest that the clinical outcome of amrubicin therapy may be associated with genetic variations in patients. Further study of combination regimens in patients of different ethnicities is warranted.

Therapeutic potential and molecular mechanism of a novel sulfonamide anticancer drug, indisulam (E7070) in combination with CPT-11 for cancer treatment

PURPOSE

Indisulam (N-(-3-chloro-7-indolyl)-1,4-benzenedisulfonamide; E7070) is an experimental anticancer agent. Microarray analysis indicates that indisulam downregulates several genes involved in drug resistance, and this finding led us to test the effect of combining indisulam with other anticancer drugs. We investigated the antitumor effect and mechanism of synergism when indisulam was administered in combination with CPT-11.

METHODS

In vitro cytotoxic activity was examined using a cell counter kit, and the combination effect was determined by isobologram analysis. The level of topoisomerase IIα was measured by Western blotting. The in vivo antitumor effect was assessed in mice inoculated with human colorectal cancer SW620 cells.

RESULTS

Isobologram analysis indicated that a 24-h exposure to indisulam and SN-38, an active metabolite of CPT-11, had a synergistic effect in HCT116 and SW620 cells and an additive effect in HCT15 and WiDr cells. Prolongation of exposure to 48 h resulted in a synergistic effect in HCT15 and WiDr cells. Treatment with SN-38 alone increased the amount of intracellular topoisomerase IIα in all cell lines tested. Co-treatment with indisulam suppressed the SN-38-induced upregulation of topoisomerase IIα after 24 h of exposure in HCT116 and SW620 cells and after 48 h of exposure in HCT15 and WiDr cells. This apparent association between a synergistic effect and suppression of SN-38-mediated upregulation of topoisomerase IIα suggests that indisulam enhances SN-38 cytotoxicity by suppressing topoisomerase IIα upregulation to compensate for topoisomerase I inhibition by SN-38. Synergy was also observed in xenografted tumors and was accompanied by complete suppression of topoisomerase IIα upregulation induced by CPT-11 treatment.

CONCLUSION

These observations prompted the clinical evaluation of indisulam and CPT-11 combination therapy.

Emerging drugs for small cell lung cancer--an update

INTRODUCTION

Small cell lung cancer (SCLC) is a biologically complex tumor whose medical treatment has remained largely unchanged over the last 30 years. The frustration for the invariably negative results reported in the early 2000s in clinical studies investigating new agents for this disease have contributed to the little interest shown by pharmaceutical industries in funding SCLC research. However, recent advances in the molecular understanding of the oncogenic mechanisms underlying SCLC have renewed the attraction for the clinical development of novel active drugs for the treatment of this challenging disease.

AREAS COVERED

The authors briefly touch on the most promising agents under clinical development for the treatment of SCLC, either chemotherapeutic or targeted drugs. Relevant and recent (2 years) studies obtained through Pubmed literature research or released at International scientific meetings are presented.

EXPERT OPINION

The data discussed herein provide evidence in support of the fact that only rationally designed clinical trials including relevant translational research may lead to successful results. Therefore, a thoughtful change in trial construction is crucial for the approval of new active drugs for this orphan disease.