Amrubicin for the Treatment of Small Cell Lung Cancer: Does Effectiveness Cross the Pacific?

Carbohydrate-based drugs launched during 2000-2021

Carbohydrates are fundamental molecules involved in nearly all aspects of lives, such as being involved in formating the genetic and energy materials, supporting the structure of organisms, constituting invasion and host defense systems, and forming antibiotics secondary metabolites. The naturally occurring carbohydrates and their derivatives have been extensively studied as therapeutic agents for the treatment of various diseases. During 2000 to 2021, totally 54 carbohydrate-based drugs which contain carbohydrate moities as the major structural units have been approved as drugs or diagnostic agents. Here we provide a comprehensive review on the chemical structures, activities, and clinical trial results of these carbohydrate-based drugs, which are categorized by their indications into antiviral drugs, antibacterial/antiparasitic drugs, anticancer drugs, antidiabetics drugs, cardiovascular drugs, nervous system drugs, and other agents.

Phase I Study of Amrubicin and Cyclophosphamide in Patients With Advanced Solid Organ Malignancies: HOG LUN 07-130

OBJECTIVES

Relapsed small cell lung cancer (SCLC) has limited treatment options. Anthracyclines and cyclophosphamide have shown synergy in many tumors. Amrubicin (AMR) and cyclophosphamide both have single-agent activity in SCLC. This phase I trial evaluated the combination of AMR and cyclophosphamide in refractory solid organ malignancies and in relapsed SCLC.

MATERIALS AND METHODS

The primary endpoint was to determine maximum-tolerated dose and dose-limiting toxicities of the combination. Eligible patients were enrolled in sequential dose escalation cohorts in a standard 3+3 design. Treatment consisted of cyclophosphamide IV at 500 mg/m on day 1 with escalating doses of AMR IV on days 1 to 3 (25 to 40 mg/m with increments of 5 mg/m per cohort). Cycles were repeated every 21 days. Exploratory objectives analyzed the presence of NQO1 polymorphisms and topoisomerase IIA amplification and correlation with response.

RESULTS

Thirty-six patients were enrolled, of whom 18 patients had SCLC (50%). Maximum-tolerated dose was determined to be dose level 2 (cyclophosphamide 500 mg/m, AMR 30 mg/m) due to grade 4 thrombocytopenia. The main grade 3 to 4 toxicities were hematologic. Efficacy results are available for 34 patients. Partial responses, stable disease, and progressive disease rates in the overall study population were 20.6% (n=7), 38.2% (n=13), and 41.2% (n=14), respectively. Partial response, stable disease, and progressive disease rates in the SCLC patients and 1 patient with extrathoracic small cell were 36.8% (n=7), 26.3% (n=5), and 36.8% (n=7), respectively. There was no correlation between topoisomerase IIA amplification or NQO1 polymorphisms and response.

CONCLUSIONS

AMR and cyclophosphamide can be safely combined with little activity observed in heavily pretreated SCLC patients.

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.

Current management of small cell lung cancer

Confined to one side of the chest, limited stage small cell lung cancer is treated with a combination of chemotherapy and radiotherapy, yet has a long-term survival rate of only 15%. Extensive stage disease has initial response rates to chemotherapy exceeding 70%. However, the disease almost invariably progresses and becomes fatal. Many recent clinical trials have failed to show superiority of newer chemotherapeutics or targeted therapies compared with the standard chemotherapy backbone of platinum plus etoposide. Numerous promising targeted therapies and other agents are still in development.

Phase II study of the histone deacetylase inhibitor Romidepsin in relapsed small cell lung cancer (Cancer and Leukemia Group B 30304)

INTRODUCTION

Treatment of small cell lung cancer (SCLC) is initially gratifying with most patients responding to platinum-based chemotherapy. Treatment of relapsed disease gives much lower response rates of short duration. We undertook this study of the protein deacetylase inhibitor Romidepsin in chemosensitive recurrent SCLC based on preclinical data that suggested this to be an active target.

METHODS

Patients had recurrent chemosensitive SCLC (relapse ≥90 days since completion of platinum-based chemotherapy). Treatment was administered as weekly infusions of Romidepsin at 13 mg/m(2) for 3 of 4 weeks. We designed a two-stage phase II study targeting a response rate of 30% (<10% response would be uninteresting and ≥30% worthy of further study).

RESULTS

Sixteen patients (10 male, 6 female) were accrued to the first stage of this study. Most (11 patients, 69%) presented with extensive-stage SCLC, and all had received prior chemotherapy, with 11 having received prior radiation. Eastern Cooperative Oncology Group performance status was excellent with 0 in 6 patients (38%) and 1 in 10 patients. No objective responses were seen, and stable disease was the best response seen in 3 patients (19%). Toxicity was modest with 3 patients suffering grade 3 toxicity (lymphopenia, insomnia, nausea, vomiting, and hyponatremia) and one patient with grade 4 thrombocytopenia. Median progression-free survival was 1.8 months, and median overall survival was 6 months.

CONCLUSION

Romidepsin given on a weekly schedule in patients with chemosensitive, recurrent SCLC was inactive and will not be pursued further in this setting.

Therapy of small cell lung cancer with emphasis on oral topotecan

Systemic chemotherapy plays the major role in the management of patients with small cell lung cancer. Cisplatin plus etoposide is the most widely used regimen and is considered as standard in patients with limited disease. Cisplatin plus irinotecan improved survival compared to cisplatin plus etoposide in a Japanese trial but failed to do so in two trials in Caucasians. Cisplatin plus topotecan had similar efficacy compared to cisplatin plus etoposide in patients with extensive disease. In the second-line setting, topotecan showed similar efficacy but better tolerability compared to cyclophosphamide, doxorubin plus vincristine. Oral topotecan was as efficacious as its intravenous formulation and was shown to improve survival compared to best supportive care alone in patients previously treated with chemotherapy. Thus topotecan is considered as the standard second-line chemotherapy in patients with small cell lung cancer.

Phase II study of amrubicin as second-line therapy in patients with platinum-refractory small-cell lung cancer

PURPOSE

Amrubicin is a synthetic anthracycline with potent topoisomerase II inhibition. This phase II study was conducted to confirm safety and activity of amrubicin in the treatment of refractory small-cell lung cancer (SCLC).

PATIENTS AND METHODS

Patients with refractory SCLC (either with progressive disease as best response or progression within 90 days of first-line therapy) received amrubicin (40 mg/m(2)/d for 3 every 21 days). The primary end point was overall response rate (ORR); secondary end points included progression-free survival (PFS), overall survival (OS), and change in left ventricular ejection fraction (LVEF).

RESULTS

Seventy-five patients with a median progression-free interval after first-line therapy of 38 days were enrolled; 69 patients received a median of four amrubicin cycles (range, one to 12 cycles). The ORR was 21.3% (95% CI, 12.7% to 32.3%), with one complete response (1.3%) and 15 partial responses (20%). Median PFS and OS were 3.2 months (95% CI, 2.4 to 4.0 months) and 6.0 months (95% CI, 4.8 to 7.1 months), respectively. The ORR in 43 patients who never responded to first-line therapy was 16.3% (95% CI, 6.8% to 30.7%). Most commonly reported grade 3 or 4 adverse events included neutropenia (67%), thrombocytopenia (41%), and anemia (30%), with febrile neutropenia in 12%. There was no decrease in mean LVEF with cumulative amrubicin doses exceeding 750 mg/m(2).

CONCLUSION

Single-agent amrubicin showed promising activity with a 21.3% ORR and an acceptable safety profile when used as second-line therapy patients with platinum-refractory SCLC. Amrubicin did not induce early cardiotoxicity, but its long-term effects are unknown.

Novel systemic therapies for small cell lung cancer

A diagnosis of small cell lung cancer (SCLC) today confers essentially the same terrible prognosis that it did 25 years ago, when common use of cisplatin-based chemotherapy began for this disease. In contrast to past decades of research on many other solid tumors, studies of combination chemotherapy using later generation cytotoxics and targeted kinase inhibitors have not had a significant impact on standard care for SCLC. The past few years have seen suggestions of incrementally improved outcomes using standard cytotoxics, including cisplatin-based combination studies of irinotecan and amrubicin by Japanese research consortia. Confirmatory phase III studies of these agents are ongoing in the United States. Antiangiogenic strategies are also of primary interest and are in late-phase testing. Several novel therapeutics, including high-potency small molecule inhibitors of Bcl-2 and the Hedgehog signaling pathway, and a recently discovered replication-competent picornavirus, have shown remarkable activity against SCLC in preclinical models and are currently in simultaneous phase I clinical development. Novel therapeutic approaches based on advances in understanding of the biology of SCLC have the potential to radically change the outlook for patients with this disease.