In vivo efficacy and tumor-selective metabolism of amrubicin to its active metabolite

Metabolic carbonyl reduction of anthracyclines - role in cardiotoxicity and cancer resistance. Reducing enzymes as putative targets for novel cardioprotective and chemosensitizing agents

Anthracycline antibiotics (ANT), such as doxorubicin or daunorubicin, are a class of anticancer drugs that are widely used in oncology. Although highly effective in cancer therapy, their usefulness is greatly limited by their cardiotoxicity. Possible mechanisms of ANT cardiotoxicity include their conversion to secondary alcohol metabolites (i.e. doxorubicinol, daunorubicinol) catalyzed by carbonyl reductases (CBR) and aldo-keto reductases (AKR). These metabolites are suspected to be more cardiotoxic than their parent compounds. Moreover, overexpression of ANT-reducing enzymes (CBR and AKR) are found in many ANT-resistant cancers. The secondary metabolites show decreased cytotoxic properties and are more susceptible to ABC-mediated efflux than their parent compounds; thus, metabolite formation is considered one of the mechanisms of cancer resistance. Inhibitors of CBR and AKR were found to reduce the cardiotoxicity of ANT and the resistance of cancer cells, and therefore are being investigated as prospective cardioprotective and chemosensitizing drug candidates. In this review, the significance of a two-electron reduction of ANT, including daunorubicin, epirubicin, idarubicin, valrubicin, amrubicin, aclarubicin, and especially doxorubicin, is described with respect to toxicity and efficacy of therapy. Additionally, CBR and AKR inhibitors, including monoHER, curcumin, (−)-epigallocatechin gallate, resveratrol, berberine or pixantrone, and their modulating effect on the activity of ANT is characterized and discussed as potential mechanism of action for novel therapeutics in cancer treatment.

Relapsed small cell lung cancer: treatment options and latest developments

According to recent analyses, there was a modest yet significant improvement in median survival time and 5-year survival rate of limited stage small cell lung cancer (SCLC) in North America, Europe, Japan and other countries over the last 30 years. The median survival time of limited stage SCLC is 15-20 months and 5-year survival rate is 15% or less. In terms of extensive stage SCLC, a median survival time of 9.4-12.8 months and 2-year survival of 5.2-19.5% are still disappointing. Despite being highly sensitive to first-line chemotherapy and radiotherapy treatments, most patients with SCLC experience relapse within 2 years and die from systemic metastasis. While several clinical trials of cytotoxic chemotherapies and molecular targeting agents have been investigated in the treatment of relapsed SCLC, none showed a significant clinical activity to be able to exceed topotecan as second-line chemotherapy. There are problematic issues to address for relapsed SCLC, such as standardizing the treatment for third-line chemotherapy. Topotecan alone was the first approved therapy for second-line treatment for relapsed SCLC. Amrubicin is a promising drug and a variety of trials evaluating its efficacy have been carried out. Amrubicin has shown superiority to topotecan in a Japanese population, but was not superior in a study of western patients. There are some controversial issues for relapsed SCLC, such as treatment for older patients, third-line chemotherapy and efficacy of molecular targeting therapy. This article reviews current standard treatment, recent clinical trials and other topics on relapsed SCLC.

A phase I study of amrubicin and fixed dose of irinotecan (CPT-11) in relapsed small cell lung cancer: Japan multinational trial organization LC0303

PURPOSE

To determine the maximum tolerated dose of amrubicin (AMR) with a fixed dose of irinotecan (CPT-11).

METHODS

Patients having pathologically proven small cell lung cancer (SCLC) relapsed after one or two chemotherapies, and Eastern Cooperative Oncology Group performance status of 0 to 2 were eligible for the study. CPT-11 was delivered as 50 mg/m2 on days 1 and 8, every 21 days. AMR was delivered on day 1. Doses of AMR were level 1: 80 mg/m2, level 2: 90 mg/m2, and level 3: 100 mg/m2. Dose elevation was determined using the modified continuous reassessment method. Tolerability was assessed after the first cycle. Another two cycles were conducted when disease progression or unacceptable toxicities were not observed.

RESULTS

Eighteen patients (mean age: 66.3 years) were enrolled. A total of 40 courses were conducted. Grade 3/4 toxicities of the first cycle were leukocytopenia: 11 (61%, grade 3/4: 8/3); neutropenia: 15 (83%, grade 3/4: 6/9); and thrombocytopenia: three (17%, grade 3/4: 2/1). Other grade 3 toxicities observed were febrile neutropenia, one; infection, three; diarrhea, one; and dyspnea, one. Dose-limiting toxicity was observed in two of six patients at level 2 (neutropenia and febrile neutropenia) and in one of six at level 3 (thrombocytopenia and infection). The maximum tolerated dose was level 3, and so, the recommended dose for phase II trials was judged to be 90 mg/m2. Objective response was obtained in four of eight patients who were able to evaluate responses. Median survival time was 13 months, with 68% at 1-year survival rate.

CONCLUSIONS

This combination was well tolerated and showed encouraging activities in SCLC. Randomized phase II trials are being planned in chemonaive SCLC.

Drug metabolite heterogeneity in cultured single cells profiled by pico-trapping direct mass spectrometry

Aim: We investigated the heterogeneity of tafluprost metabolism in primary human hepatocytes at a single-cell level by live single-cell mass spectrometry (MS). Materials & methods: Picoliter volumes of cytoplasm were analyzed by nano-electrospray ionization MS in order to obtain single-cell metabolite profiles. The subcellular components of a single tafluprost-treated human hepatocyte were isolated and the single-cell metabolite profile was compared with those of traditional bulk hepatocyte analysis. Results: In the bulk hepatocyte analysis, liquid chromatography–MS showed the averaged metabolism of tafluprost to tafluprost acid (TA) and β-oxidized metabolites. However, live single-cell MS showed that tafluprost metabolism varied among individual cells. In addition, there was significant variation in the quantities of TA and a major metabolite, dinor-TA, among cells, whereas there was no significant variation in 7-ethoxycoumarin metabolism. Conclusion: Thus, live single-cell MS successfully detected the heterogeneity of drug metabolism in individual living hepatocytes.

Original submitted 12 May 2011; Revised submitted 6 February 2012; Published online 14 May 2012

C609T polymorphism of NAD(P)H quinone oxidoreductase 1 as a predictive biomarker for response to amrubicin

INTRODUCTION

Amrubicin is a promising agent in the treatment of lung cancer, but predictive biomarkers have not yet been described. NAD(P)H:quinone oxidoreductase 1 (NQO1) is an enzyme known to metabolize amrubicinol, the active metabolite of amrubicin, to an inactive compound. We examined the relationship between NQO1 and amrubicinol cytotoxicity.

METHODS

Gene and protein expression of NQO1, amrubicinol cytotoxicity, and C609T single-nucleotide polymorphism of NQO1 were evaluated in 29 lung cancer cell lines: 14 small cell lung cancer (SCLC) and 15 non-SCLC (NSCLC). The involvement of NQO1 in amrubicinol cytotoxicity was evaluated by small interfering RNA against NQO1.

RESULTS

A significant inverse relationship between both gene and protein expression of NQO1 and amrubicinol cytotoxicity was found in all cell lines. Treatment with NQO1 small interfering RNA increased amrubicinol cytotoxicity and decreased NQO1 expression in both NSCLC and SCLC cells. Furthermore, cell lines genotyped homozygous for the 609T allele showed significantly lower NQO1 protein expression and higher sensitivity for amrubicinol than those with the other genotypes in both NSCLC and SCLC cells.

CONCLUSIONS

NQO1 expression is one of the major determinants for amrubicinol cytotoxicity, and C609T single-nucleotide polymorphism of NQO1 could be a predictive biomarker for response to amrubicin treatment.

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

Lung cancer is the leading cause of cancer death, and approximately 15% of all lung cancer patients have small-cell lung cancer (SCLC). Although second-line chemotherapy can produce tumor regression, the prognosis is poor. Amrubicin hydrochloride (AMR) is a synthetic anthracycline anticancer agent and a potent topoisomerase II inhibitor. Here, we discuss the features of SCLC, the chemistry, pharmacokinetics, and pharmacodynamics of AMR, the results of in vitro and in vivo studies, and the efficacy and safety of AMR monotherapy and combination therapy in clinical trials. With its predictable and manageable toxicities, AMR is one of the most attractive agents for the treatment of chemotherapy-sensitive and -refractory relapsed SCLC. Numerous studies are ongoing to define the applicability of AMR therapy for patients with SCLC. These clinical trials, including phase III studies, will clarify the status of AMR in the treatment of SCLC.

Phase II trial of amrubicin and carboplatin in patients with sensitive or refractory relapsed small-cell lung cancer

Amrubicin is a novel, totally synthesized anthracycline derivative, and has antitumor activity against several human tumor xenografts. The combination of amrubicin with platinum derivative showed additive effect against a human small-cell lung cancer (SCLC) cell line. Until now, the combination of amrubicin plus carboplatin has not been studied in patients with previously treated SCLC. Therefore, we examined the safety and efficacy of the combination of amrubicin plus carboplatin in patients with sensitive or refractory relapsed SCLC. Patients with previously treated SCLC were eligible if they had a performance status of 2 or less, were 75 years or younger, and had adequate organ function. Twenty-five patients were enrolled (21 men and 4 women; median age, 65 years; age range 55-73 years). Patients received the combination of amrubicin (30 mg/m(2) on days 1-3) plus carboplatin (with a target area under the concentration-versus-time curve of 4 mg min/ml using the Calvert formula on day 1) every 3 weeks. The overall response rate was 36.0% (95% confidence interval [CI], 18.0-57.5%). Response rates differed significantly between patients with sensitive relapse (58.3%; 95% CI, 27.7-84.8%) and those with refractory relapse (15.4%; 95% CI, 1.9-15.4%; p=0.03). The median survival time (MST) from the start of this treatment was 7 months (range: 1-42 months); the MST of patients with sensitive relapse (10 months) was significantly longer than that of patients with refractory relapse (5 months: p=0.004). The median progression-free survival (PFS) time was 3 months (range: 1-14 months): the median PFS time of patients with sensitive relapse (5 months) was significantly longer than that of patients with refractory relapse (2 months; p=0.01). The most frequent grade 3-4 toxicity was myelosuppression, especially neutropenia, which developed in 88% of patients. Grade 3-4 thrombocytopenia developed in 44% of patients, and anemia developed in 56%. Nonhematologic toxicities were generally mild to moderately severe and temporary. None of the patients had cardiotoxicity. In conclusion, this therapy is effective and well tolerated for previously treated SCLC.

Over-expression of MDR1 in amrubicinol-resistant lung cancer cells

PURPOSE

Amrubicin, a totally synthetic 9-aminoanthracycline anticancer drug, has shown promising activity for lung cancer, but little is known about the mechanism of resistance for this agent. This study was aimed to clarify the role of P-glycoprotein (P-gp) in amrubicinol, an active metabolite of amrubicin, resistance in lung cancer cells.

METHODS

Amrubicinol-resistant cell line PC-6/AMR-OH was developed by continuously exposing the small-cell lung cancer cell line PC-6 to amrubicinol. Gene expression level of MDR1, which encodes P-gp, and intracellular accumulation of amrubicinol were evaluated by PC-6 and PC-6/AMR-OH cells. The involvement of MDR1 in amrubicinol resistance was evaluated by treatment with P-gp inhibitor verapamil and small interfering RNA (siRNA) against MDR1. Also, expression levels and single-nucleotide polymorphisms (SNPs) of MDR1 in 22 lung cancer cell lines were examined, and the relationships between these factors and sensitivity to amrubicinol were evaluated.

RESULTS

The MDR1 gene was increased approximately 4,500-fold in PC-6/AMR-OH cells compared with PC-6 cells, and intracellular accumulation of amrubicinol in PC-6/AMR-OH cells was decreased to about 15 percent of that in PC-6 cells. Treatment with verapamil and siRNA against MDR1 significantly increased the sensitivity to amrubicinol in PC-6/AMR-OH cells with increased cellular accumulation of amrubicinol. Meanwhile, neither MDR1 gene expression levels nor SNPs of the gene were associated with amrubicinol sensitivity.

CONCLUSIONS

Results of this study indicate that increased MDR1 expression and P-gp activity confer acquired resistance to amrubicinol. In contrast, neither expression level nor SNPs of MDR1 are likely to be predictive markers for amrubicin activity.

Recent Pharmacological Advances: Focus on Small-cell Lung Cancer

Small cell lung cancer (SCLC) represents approximately 15% of all lung cancers, and is the most aggressive form of lung cancer. Left untreated, the time from diagnosis to death is 2–3 months. With current treatment, expected survival is 7–20 months, depending on the stage of disease. A new drug, amrubicin, is approved in Japan for lung cancer and has demonstrated efficacy in U.S. and European phase II trials of SCLC patients with either untreated disease or relapsed refractory illness. In a phase II study of amrubicin in previously untreated patients, response rates reached 75% with a median survival time of almost 1 year. Amrubicin is a fully synthetic 9-aminoanthracycline, and an analog of doxorubicin and epirubicin. The major mechanism of action of amrubicin is inhibition of topoisomerase II. Unlike doxorubicin, however, it exhibits little or no cardiotoxicity in clinical studies and preclinical models. In preclinical rodent tumor models, it is selectively distributed to tumour tissue and is not detected in the heart when compared with doxorubicin, which is distributed equivalently to these sites. The primary metabolite of amrubicin, amrubicinol, is up to 100 times more cytotoxic in vitro than the parent compound. This review describes the mechanisms of action of amrubicin as well as clinical studies which demonstrate the potential of this drug in future SCLC treatment. The review also puts forward hypothetical considerations for the use of other drugs such as lenalidomide, an immunomodulatory drug acting on multiple signalling pathways, or histone deacetylase inhibitors, in combination with amrubicin in SCLC.

Efficacy of combination treatment and influence of schedule with irinotecan and amrubicin in human lung carcinoma cells in vivo and in vitro

The aim of this study was to elucidate the efficacy of combination therapy with irinotecan and amrubicin for lung cancer and the influence of administration schedule in a xenograft mouse model and human cancer cell culture. We investigated the antitumor activity of irinotecan and amrubicin on human small cell lung cancer cell line LX-1 inoculated in mice in vivo and the cytotoxic effect of SN-38 and amrubicinol on human lung cancer cell lines A549 and PC-6 in vitro. Combined administration of irinotecan and amrubicin in divided doses inhibited tumor growth by approximately 90%, with complete recovery observed in one case. Furthermore, combined administration in divided doses induced little loss of body weight. Combination index analysis revealed that the cell growth inhibitory effect of SN-38 combined with amrubicinol was additive, regardless of schedule or cell line. The effect of combination treatment with SN-38 and amrubicinol on cell cycle was investigated. Cell cycle showed arrest at both the S and G2/M phases. The results indicate that combination therapy with irinotecan and amrubicin can be expected to yield improved outcomes, including less toxicity, especially with divided administration.

Amrubicin for the treatment of advanced lung cancer

Although the advancement of the chemotherapy of non-small cell lung cancer and small cell lung cancer is remarkable in recent years, it is still unsatisfactory. Therefore, some new agents or a new treatment strategy for lung cancer is required. Amrubicin is a totally synthetic anthracycline anticancer drug that acts as a potent topoisomerase II inhibitor. Recently, amrubicin has been approved in Japan for the treatment of small- and non-small cell lung cancers and some clinical trials about amrubicin were conducted in Japan, and promising results have been reported for the treatment of small cell lung cancer in particular. The preclinical, pharmacology and clinical data of amrubicin for the treatment of advanced lung cancer are reviewed.

Retrospective analysis of efficacy and safety of amrubicin in refractory and relapsed small-cell lung cancer

BACKGROUND

Amrubicin, a totally synthetic 9-aminoanthracycline, was evaluated retrospectively for the treatment of refractory and relapsed small-cell lung cancer (SCLC).

METHODS

Retrospective analysis was performed in 32 patients. Amrubicin was infused over 5 min on days 1-3, with courses repeated at 3- or 4-week intervals. Amrubicin was given at a dose of 45 mg/m(2) per day, 40 mg/m(2) per day, 35 mg/m(2) per day, 30 mg/m(2) per day, or 25 mg/m(2) per day depending on medical conditions (patients' age and performance status [PS]), and the dose was modulated according to myelosuppression.

RESULTS

The median number of treatment cycles was 3 (range, 1-6). Seventeen patients (53.1%) had a partial response. Median progression-free survival time for all patients was 96 days, and median survival time was 166 days. Grade 3 or 4 hematologic toxicities comprised neutropenia (78.1%), anemia (65.6%), and thrombocytopenia (50.0%). Febrile neutropenia was observed in 8 patients (25.0%). Nonhematologic toxicities were mild. Treatment-related death was observed in 1 patient.

CONCLUSION

Treatment with amrubicin appeared effective in SCLC patients previously treated with chemotherapy, although it was not necessarily safe, because of myelosuppression. Further research is warranted to investigate amrubicin treatment for patients with SCLC.

Next-generation anthracycline for the management of small cell lung cancer: focus on amrubicin

Amrubicin is a totally synthetic anthracycline anticancer agent that acts as a potent topoisomerase II inhibitor. Amrubicin has been approved in Japan for the treatment of lung cancer, and the results from clinical studies of amrubicin as a single agent or as part of combination regimens for lung cancer, particularly for small cell lung cancer, conducted in Japan and overseas have been promising. Amrubicin should be included among new treatment strategies especially for chemoresistant patients. Here, preclinical, pharmacological, and clinical data on the use of amrubicin for the treatment of small cell lung cancer are reviewed.

Amrubicin for non-small-cell lung cancer and small-cell lung cancer

Amrubicin is a totally synthetic anthracycline anticancer drug and a potent topoisomerase II inhibitor. Recently, amrubicin was approved in Japan for the treatment of small- and non-small-cell lung cancers (SCLC and NSCLC). Here, we review the efficacy and toxicities of amrubicin monotherapy and amrubicin in combination with cisplatin for extensive-disease SCLC (ED-SCLC), and of amrubicin monotherapy for advanced NSCLC, as observed in the clinical trials. Recommended dosage for previously untreated advanced NCSLC was 45 mg/m2/day by intravenous administration for 3 days. Dose-limiting toxicities were leucopenia, thrombocytopenia, and gastrointestinal disturbance. Response rate was 27.9% for advanced NSCLC, and 75.8% for ED-SCLC with a median survival time (MST) of 11.7 months. Recommended dosage of amrubicin was 40 mg/m2/day in combination with cisplatin at 60 mg/m2/day, with MST of 13.6 months and 1-year survival rate of 56.1%. In sensitive or refractory relapsed SCLC, response rate was 52 and 50%, progression-free survival was 4.2 and 2.6 months, overall survival was 11.6 and 10.3 months, and 1-year survival rate was 46 and 40%, respectively. These results are promising for the treatment of both NSCLC and SCLC. Further clinical trials will clarify the status of amrubicin in the treatment of lung cancer.

Phase II study of amrubicin, 9-amino-anthracycline, in patients with advanced non-small-cell lung cancer: a West Japan Thoracic Oncology Group (WJTOG) study

PURPOSE

We conducted a multicenter phase II study of amrubicin, a novel 9-aminoanthracycline, to evaluate its efficacy and safety in patients with non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

Entry requirements included cytologically or histologically proven measurable NSCLC, stage III or IV, no prior therapy, an Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 2, and adequate organ function. Amrubicin was given by daily intravenous injection at 45 mg/m2/day for three consecutive days, repeated at 3 week intervals. Each patient received at least three treatment cycles.

RESULTS

Sixty-two patients were enrolled in this study. Of the 62 registered patients, 60 were eligible and assessable for efficacy, and 59 for toxicity. Overall response rate was 18.3% (95% confidence interval [CI], 9.5 to 30.4%) and median survival time was 8.2 months (95% CI, 6.7 to 10.4 months). Major toxicity was myelosuppression, with incidences of grade 3 or 4 toxicity of 78.0% for neutropenia, 54.2% for leukopenia, 30.5% for anemia, and 28.8% for thrombocytopenia. Non-hematological toxicities with a greater than 50% incidence were anorexia (69.5%), nausea/vomiting (55.9%), and alopecia (75.9%), but were relatively mild, with grade 3 toxicities observed in only one patient each (1.7%).

CONCLUSION

Amrubicin was an active, well-tolerated agent in the treatment of NSCLC.

Treatment options for relapsed small-cell lung cancer

Small-cell lung cancer is a chemo-sensitive disease with a response rate ranging from 70 to 90% for first-line treatment; however, relapses are very common and as a result long-term survival is poor. Chemotherapy has demonstrated a benefit over the best supportive care, even in patients who have relapsed after initial treatment with a platinum-based regimen. Agents currently being used in salvage therapy include topotecan, cyclophosphamide, doxorubicin and vincristine regimen. In the last 5 years, several drugs have shown promise in initial evaluation; however, randomized phase III trials would be needed to answer this question. Our understanding of the biology of small-cell lung cancer has improved dramatically over the past few years and this has translated into the developments of new therapeutic targets for this disease. Agents affecting several targets, including bcl-2, matrix metalloproteinases, epidermal growth factors and angiogenesis, are being studied currently and have the potential to change the treatment paradigms of this otherwise fatal malignancy. This review focuses on the various current and future options, including cytoxic and targeted agents, for salvage therapy in patients with this disease.

Amrubicin, a novel 9-aminoanthracycline, enhances the antitumor activity of chemotherapeutic agents against human cancer cells in vitro and in vivo

Amrubicin, a completely synthetic 9-aminoanthracycline derivative, is an active agent in the treatment of untreated extensive disease-small-cell lung cancer and advanced non-small-cell lung cancer. Amrubicin administered intravenously at 25 mg/kg substantially prevented the growth of five of six human lung cancer xenografts established in athymic nude mice, confirming that amrubicin as a single agent was active in human lung tumors. To survey which antitumor agent available for clinical use produces a synergistic interaction with amrubicin, we examined the effects in combinations with amrubicinol, an active metabolite of amrubicin, of several chemotherapeutic agents in vitro using five human cancer cell lines using the combination index (CI) method of Chou and Talalay. Synergistic effects were obtained on the simultaneous use of amrubicinol with cisplatin, irinotecan, gefitinib and trastuzumab, with CI values after 3 days of exposure being <1. Additive effect was observed with the combination containing vinorelbine with CI values indistinguishable from 1, while the combination of amrubicinol with gemcitabine was antagonistic. All combinations tested in vivo were well tolerated. The combinations of cisplatin, irinotecan, vinorelbine, trastuzumab, tegafur/uracil, and to a lesser extent, gemcitabine with amrubicin caused significant growth inhibition of human tumor xenografts without pronouncedly enhancing body weight loss, compared with treatment using amrubicin alone at the maximum tolerated dose. Growth inhibition of tumors by gefitinib was not antagonized by amrubicin. These results suggest that amrubicin appears to be a possible candidate for combined use with cisplatin, irinotecan, vinorelbine, gemcitabine, tegafur/uracil or trastuzumab.

Amrubicin induces apoptosis in human tumor cells mediated by the activation of caspase-3/7 preceding a loss of mitochondrial membrane potential

Amrubicin, a completely synthetic 9-aminoanthracycline derivative, inhibits cell growth by stabilizing a topoisomerase II-DNA complex. This study was designed to examine the apoptosis induced in human leukemia U937 cells by amrubicin and its active metabolite amrubicinol. Amrubicin, amrubicinol and other antitumor agents, such as daunorubicin and etoposide, induced typical apoptosis with characteristic nuclear morphological change and DNA fragmentation. Measuring the population of sub-G(1) phase cells, it was found that under conditions where cell growth was inhibited by either amrubicin or amrubicinol, U937 cells underwent apoptotic cell death in a dose-dependent manner accompanied by an arrest of the cell cycle at G(2)/M. Furthermore, amrubicin- and amrubicinol-induced apoptosis was mediated by the activation of caspase-3/7, but not caspase-1, preceding a loss of mitochondrial membrane potential. These results indicate that both a reduction in mitochondrial membrane potential and the activation of caspase-3/7 are key events in the apoptosis induced by amrubicin and amrubicinol as well as the other antitumor agents. In addition, studies with oligomycin suggested that the apoptosis induced by amrubicin and amrubicinol involved substantially different pathways from that triggered by daunorubicin and etoposide. Oligomycin blocked the etoposide-induced increase in the number of sub-G(1) phase cells without preventing the activation of caspase-3/7, and had no inhibitory effect on the expansion of the sub-G(1) population in daunorubicin-treated cells, whereas apoptosis-related changes caused by amrubicin and amrubicinol were suppressed in the presence of oligomycin.

Phase II study of amrubicin in previously untreated patients with extensive-disease small cell lung cancer: West Japan Thoracic Oncology Group (WJTOG) study

PURPOSE

To evaluate the efficacy and safety of amrubicin, (+)-(7S, 9S)-9-acetyl-9-amino-7-[(2-deoxy-beta-D-erythro-pentopyranosyl )oxy]-7,8,9,10-tetrahydro-6,11-dihydroxy-5,12-naphthacenedione hydrochloride, in previously untreated patients with extensive-disease small cell lung cancer (SCLC).

PATIENTS AND METHODS

A total of 35 previously untreated patients with extensive-disease SCLC were entered into the study. Amrubicin was given by daily intravenous infusion at 45 mg/m(2)/day for 3 consecutive days, every 3 weeks. Unless there was tumor regression of 25% or greater after the first cycle, or 50% or greater after the second cycle, treatment was switched to salvage chemotherapy in combination with etoposide (100 mg/m(2), days 1, 2, and 3) and cisplatin (80 mg/m(2), day 1).

RESULTS

Of the 35 patients entered, 33 were eligible and assessable for efficacy and toxicity. Of the 33 patients, 3 (9.1%) had a complete response (95% confidence interval [CI], 1.9-24.3%) and 22 had a partial response, for an overall response rate of 75.8% (95% CI, 57.7-88.9%). Median survival time was 11.7 months (95% CI, 9.9-15.3 months), and 1-year and 2-year survival rates were 48.5% and 20.2%, respectively. The most common toxicity was hematologic. Non-hematologic toxicity of grade 3 or 4 was only seen in 3 patients with anorexia (9.1%) and 1 patient with alopecia (3.0%). Salvage chemotherapy was administered to only 6 patients.

CONCLUSION

Amrubicin was active for extensive-disease SCLC with acceptable toxicity. Further studies in combination with other agents for SCLC are warranted.

A phase I and pharmacological study of amrubicin and topotecan in patients of small-cell lung cancer with relapsed or extensive-disease small-cell lung cancer

Cisplatin-based chemotherapy is considered to be a standard treatment in patients with relapsed or extensive-disease (ED) small-cell lung cancer (SCLC), the survival benefit remains modest. Relapsed or ED-SCLC patients were enrolled. Topotecan and amrubicin were administered on Days 1-5 and on Days 3-5, respectively. Nine patients received a total of 24 cycles. Since all three patients experienced dose-limiting toxicity (grade 4 neutropenia lasting for more than 4 days, grade 3 febrile neutropenia, and grade 4 thrombocytopenia) at the third dose level (topotecan: 0.75 mg/m2, amrubicin 40 mg/m2), the maximum tolerated dose was determined to be this dose level. Objective response was observed in six patients (67%). The maximum concentration (Cmax) and area under the plasma concentration-time curve (AUC) of amrubicin increased in a dose-dependent manner. Amrubicin did not influence the pharmacokinetics of topotecan. The Cmax and AUC of amrubicin were correlated with the duration of grade 4 neutropenia. The mean Cmax of topotecan on day 2 in responders (22.9+/-3.6) was significantly higher than that in non-responders (10.9+/-0.4). This phase I study showed the safety and activity of two-drug combination of amrubicin and topotecan in patients with relapsed or ED-SCLC.

Fulminant hepatic failure resulting from small-cell lung cancer and dramatic response of chemotherapy

Prompt treatment in tumor-associated encephalopathy may prolong survival. We describe a 69-year-old male patient who was presented with fulminant hepatic failure, secondary to small-cell lung carcinoma with rapidly progressing encephalopathy. Both symptoms remitted following chemotherapy, suggesting swift diagnosis and administration of chemotherapy to be effective in treatment of fulminant hepatic failure and encephalopathy.

Multicenter phase II study of amrubicin, 9-amino-anthracycline, in patients with advanced non-small-cell lung cancer (Study 1): West Japan Thoracic Oncology Group (WJTOG) trial

PURPOSE

Amrubicin is a novel 9-aminoanthracycline. This multicenter phase II study was conducted to evaluate the efficacy and safety of amrubicin in patients with non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

Sixty-one previously untreated patients with stage III or IV NSCLC were entered this study. The patients were required to have cytologically or histologically proven measurable NSCLC, an Eastern Cooperative Oncology Group (ECOG) performance status of 0-2, and adequate organ function. Amrubicin was administered by daily intravenous injection at 45 mg/m2/day for 3 consecutive days every 3 weeks. At least 3 cycles of treatment were administered to each patient.

RESULTS

All 61 patients registered in this trial were eligible and assessable for efficacy and toxicity. Of them, 17 patients achieved objective responses, consisting of one complete response and 16 partial responses, and the overall response rate was 27.9% (95% confidence interval [CI], 17.1% to 40.8%). The median survival time was 9.8 months (95% CI, 7.7 months to 14.9 months). The major toxicity was myelosuppression. The incidences of grade 3 or 4 toxicity were 72.1% for neutropenia, 52.5% for leukopenia, 23.0% for anemia, and 14.8% for thrombocytopenia. As noticeable toxic events, grade 3 hypotention and alkaline phosphatase elevation were transiently observed in one patient each. In addition, three patients who had had asymptomatic interstitial pneumonitis, identified by diagnostic imaging before treatment, aggravated after amrubicin treatment; two of them died. Other non-hematologic toxicities were relatively mild.

CONCLUSION

Amrubicin was an active, well-tolerated agent in the treatment of NSCLC.

Phase I study of amrubicin hydrochloride and cisplatin in patients previously treated for advanced non-small cell lung cancer

OBJECTIVE

A single-center phase I trial was designed to determine both the dose-limiting toxicities and the maximum tolerated dose (MTD) for amrubicin hydrochloride in combination therapy with cisplatin for advanced non-small cell lung cancer (NSCLC) patients with prior chemotherapy.

METHODS

Eligible patients received amrubicin and cisplatin on days 1 through 3 every 3 or 4 weeks. Cisplatin was administered at a fixed dosage of 20 mg/m(2) while the administered dose of amrubicin was started at 20 mg/m(2). Each group comprised 3 or 6 patients. When dose limiting toxicities were noted in three or more of six patients at a particular level, that level was estimated to be the MTD.

RESULTS

Fifteen patients were enrolled in this study, including 5 males and 10 females, with a median age of 57. The dose limiting toxicities included grade 4 neutropenia which lasted 4 or more days and febrile neutropenia. The non-hematologic toxicities were well managed and rarely severe. The MTD of amrubicin in this combination regimen was estimated to be 30 mg/m(2).A partial response was observed in 4 of 15 patients (27%).

CONCLUSIONS

The recommended dose was thus determined to be 25 mg/m(2) amrubicin with 20 mg/m(2) cisplatin for 3 consecutive days. A phase II study is currently underway.

[Development of an individualized therapy for establishing the optimal dosage by the pharmacokinetics profiles of anticancer agents]

Therapeutic drug monitoring (TDM) is widely applied to a variety of medications, including antibiotics, immunosuppressants, and antidepressants, but the clinical utility of TDM for anticancer agents is currently limited by several factors. The primary reason is the poorly-defined concentration-effect relationships for most anticancer drugs. TDM has the potential to improve the clinical use of anticancer agents. This paper reviews the relations between the pharmacokinetics of a new anticancer agent, amrubicin, and the clinical response and toxic side effects in patients. The plasma concentration of amrubicin peaked immediately after a bolus intravenous injection of the drug and declined in a biexponential manner thereafter, whereas that of C-13 hydroxy metabolite amrubicinol also peaked just after amrubicin injection but decreased more gradually compared with that of amrubicin. The apparent total clearance of amrubicin showed a large interindividual variability, despite adjustment of dosage for body surface area. Leukocytopenia of grades 3 or 4 occurred in most patients, and thrombocytopenia and anemia of grades 3 or 4 were also common. Since the area-under the curves of amrubicin and amrubicinol seemed to be associated with the severity of hematological toxicities, it is thought that the plasma concentration of amrubicin and amrubicinol may provide useful information for establishing the optimal dosage of amrubicin in each patient.

Phase I/II study of amrubicin, a novel 9-aminoanthracycline, in patients with advanced non-small-cell lung cancer

PURPOSE

Amrubicin is a novel, totally synthetic 9-aminoanthracycline. The present phase I/II study was performed to define its maximum-tolerated dose (MTD), efficacy and toxicity in the treatment of previously untreated patients with advanced non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

Chemonaive patients were required to have cytologically or histologically proven measurable NSCLC, an Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0 to 2, and adequate organ functions. Amrubicin was administered by daily intravenous injection for 3 consecutive days every 3 weeks.

RESULTS

In a phase I study, four patients were enrolled at dose level 1 (40 mg/m(2)/day) and four at dose level 2 (45 mg/m(2)/day). No dose limiting toxicity (DLT), which was defined as toxicity consisting of grade 4 neutropenia and leukopenia lasting four days or more, and grade 3 or 4 toxicity other than neutropenia, leukopenia, anorexia, nausea/vomiting, and alopecia, was observed at these dose levels. Subsequently, at dose level 3 (50 mg/m(2)/day), 3 of 5 patients experienced DLTs (leukopenia, neutropenia, thrombocytopenia, or gastrointestinal complications). The MTD and recommended dose (RD) were determined to be 50 mg/m(2)/day and 45 mg/m(2)/day, respectively. Three partial responses (PRs) were achieved in 13 patients (response rate, 23.1%) in a phase I study. In a phase II study, 15 patients were assessable for efficacy and toxicity at the RD, and four PRs were obtained (response rate, 26.7%). The major toxicities were leukopenia and neutropenia, while non-hematologic toxicities were mild. The overall response rate in the combined patient population of the phase I/II study was 25.0% (7 PRs in 28 patients), with a 95% confidence interval of 10.7% to 44.9%.

CONCLUSION

Amrubicin exerted promising antitumor activity on NSCLC with acceptable toxicity.

Phase I and pharmacokinetic study of amrubicin, a synthetic 9-aminoanthracycline, in patients with refractory or relapsed lung cancer

Amrubicin is a novel synthetic 9-aminoanthracycline derivative and is converted enzymatically to its C-13 hydroxy metabolite, amrubicinol, whose cytotoxic activity is 10-100 times that of amrubicin. We aimed to determine the maximum tolerated dose (MTD) of amrubicin and to characterize the pharmacokinetics of amrubicin and amrubicinol in previously treated patients with refractory or relapsed lung cancer. The 15 patients were treated with amrubicin intravenously at doses of 30, 35, or 40 mg/m(2) on three consecutive days every 3 weeks for a total of 43 courses. Neutropenia was the major toxicity (grade 4, 67%). The MTD was 40 mg/m(2), with the specific dose-limiting toxicities being grade 4 neutropenia persisting for >4 days, febrile neutropenia, or grade 3 arrhythmia in the three patients treated at this dose. A patient with non-small-cell lung cancer showed a partial response, and ten individuals experienced a stable disease. The area under the plasma concentration versus time curve (AUC) for amrubicin and that for amrubicinol increased with amrubicin dose. The amrubicin AUC was significantly correlated with the amrubicinol AUC. The recommended phase II dose of amrubicin for patients with lung cancer refractory to standard chemotherapy is thus 35 mg/m(2) once a day for three consecutive days every 3 weeks.

Phase I–II study of amrubicin and cisplatin in previously untreated patients with extensive-stage small-cell lung cancer

BACKGROUND

Amrubicin, a totally synthetic 9-amino-anthracycline, demonstrated excellent single-agent activity for extensive-stage small-cell lung cancer (ED-SCLC). The aims of this trial were to determine the maximum-tolerated doses (MTD) of combination therapy with amrubicin and cisplatin, and to assess the efficacy and safety at their recommended doses (RD).

PATIENTS AND METHODS

Eligibility criteria were patients having histologically or cytologically proven measurable ED-SCLC, no previous systemic therapy, an Eastern Cooperative Oncology Group performance status of 0-2 and adequate organ function. Amrubicin was administered on days 1-3 and cisplatin on day 1, every 3 weeks.

RESULTS

Four patients were enrolled at dose level 1 (amrubicin 40 mg/m(2)/day and cisplatin 60 mg/m(2)) and three patients at level 2 (amrubicin 45 mg/m(2)/day and cisplatin 60 mg/m(2)). Consequently, the MTD and RD were determined to be at level 2 and level 1, respectively. The response rate at the RD was 87.8% (36/41). The median survival time (MST) was 13.6 months and the 1-year survival rate was 56.1%. Grade 3/4 neutropenia and leukopenia occurred in 95.1% and 65.9% of patients, respectively.

CONCLUSIONS

The combination of amrubicin and cisplatin has demonstrated an impressive response rate and MST in patients with previously untreated ED-SCLC.

Hematological aspects of a novel 9-aminoanthracycline, amrubicin

Our previous study showed that the myelosuppression induced by a single-bolus intravenous injection of amrubicin into mice was more severe, even at half the maximum tolerated dose (MTD), than that induced by adriamycin (ADR) at the MTD, but that the recovery was more rapid than that after ADR. The present study shows that the administration of amrubicin significantly decreased the number of colony-forming units of granulocytes and monocytes (CFU-GM) from day 1, but that the CFU-GM numbers recovered by day 3. In contrast, the administration of ADR induced a continuous decrease in the numbers of CFU-GM until day 10. The early myelosuppression and rapid recovery of white blood cells (WBC) induced by amrubicin may depend upon the early decrease in the number of CFU-GM and the rapid recovery of CFU-GM. These data suggest that the toxic effects on the peripheral blood and bone marrow induced by amrubicin are more reversible and more controllable than those induced by ADR.

[Profile of the anti-tumor effects of amrubicin, a completely synthetic anthracycline]

Amrubicin is a completely synthetic anthracycline derivative. In contrast, however, the anthracyclines used clinically thus far have been produced by fermentation or semisynthesis. Amrubicin is structurally distinguishable from other anthracyclines by the amino group at the 9-position and its unique sugar moiety. Amrubicinol, the C-13 hydroxy- metabolite of amrubicin, is associated with a 5 to 200 times greater cytotoxicity than amrubicin. Amrubicin exhibited superior in vivo antitumor activity to doxorubicin in the human tumor xenograft model. Using this model, the level of amrubicinol (active metabolite) was shown to be higher than that of doxorubicin in tumor tissues, but lower in normal tissues. These results suggest potent therapeutic activity for amrubicin because of the selective distribution of its highly active metabolite, amrubicinol, in tumors. These anti-tumor effects of amrubicin are considered to be induced by DNA topoisomeraseII inhibition. In clinical studies, amrubicin has demonstrated potent single agent activity as compared to a standard regimen in untreated patients with extensive small cell lung cancer. Its major toxicity was myelosuppression (especially neutropenia).

Uptake and intracellular distribution of amrubicin, a novel 9-amino-anthracycline, and its active metabolite amrubicinol in P388 murine leukemia cells

Amrubicin, a 9-aminoanthracycline anti-cancer drug, and its C-13 hydroxyl metabolite amrubicinol, were examined for growth-inhibitory activity as well as cellular uptake and distribution in P388 murine leukemia cells and doxorubicin-resistant P388 cells. Also discussed are the differences in the mechanisms of action among amrubicin, amrubicinol and doxorubicin in terms of their cellular pharmacokinetic character. In P388 cells, amrubicinol was about 80 times as potent as amrubicin, and about 2 times more potent than doxorubicin in a 1-h drug exposure growth-inhibition test. A clear cross-resistance was observed to both amrubicin and amrubicinol in doxorubicin-resistant P388 cells, though the resistance index was lower for amrubicin. The intracellular concentration of amrubicinol was about 6 times and 2 times higher than those of amrubicin and doxorubicin, respectively. Compared to doxorubicin, amrubicin and amrubicinol were released rapidly after removal of the drugs from the medium. A clear correlation was found between the growth-inhibiting activity and the cellular level of amrubicin and amrubicinol in P388 cells. About 10 to 20% of amrubicin or amrubicinol taken up by the cells was detected in the cell nuclear fraction, whereas 70 to 80% of doxorubicin was localized in this fraction. These results suggest that amrubicin and amrubicinol exert cytotoxic activity via a different mechanism from that of doxorubicin.

Tumor-selective distribution of an active metabolite of the 9-aminoanthracycline amrubicin

It has been reported that the 9-aminoanthracycline amrubicin shows good efficacy in human tumor xenograft models. We studied the disposition and metabolism of amrubicin in mice, in comparison with those of doxorubicin. Amrubicinol, a 13-hydroxy metabolite of amrubicin, which is 10 to 100 times more cytotoxic than amrubicin, was detected as a major metabolite in blood and tissues, and aglycones of amrubicin were also detected. A pharmacokinetic study revealed that amrubicin had a smaller distribution volume and a shorter half-life than doxorubicin. In several normal tissues, the levels of amrubicin and amrubicinol were lower than those of doxorubicin. In contrast, the tumor levels of amrubicinol in the mice treated with amrubicin were higher than those of doxorubicin in the mice treated with that drug, in tumors that are sensitive to amrubicin. These results suggest that the potent therapeutic activity of amrubicin is caused by the selective distribution of its highly active metabolite, amrubicinol, in tumors.

Cytotoxicity of amrubicin, a novel 9-aminoanthracycline, and its active metabolite amrubicinol on human tumor cells

Amrubicin, a completely synthetic 9-aminoanthracycline derivative, was previously shown to have potent antitumor activities against various human tumor xenografts. In this study, the in vitro activities of amrubicin and its major metabolite, amrubicinol, were examined using 17 human tumor cell lines. Amrubicinol was 5 to 54 times more potent than amrubicin, and as potent as doxorubicin, in inhibiting the growth of the cells following 3-day continuous drug exposure. Amrubicinol closely resembled doxorubicin in its profile of activities on the 17 human tumor cell lines. Cells were incubated with the drugs for 1 h, and the intracellular drug concentration and cell growth inhibition after 3 days were determined. Amrubicinol attained similar intracellular concentrations at lower medium concentrations compared to amrubicin, and the intracellular concentration of amrubicinol necessary to produce 50% cell growth inhibition was 3 to 8 times lower than that of amrubicin in 4 cell lines tested. Amrubicinol has a higher activity level inside the cells than does amrubicin. When cells were incubated with amrubicin for 5 h, a substantial amount of amrubicinol, more than 9% of that of amrubicin, was found in cells in 4 of the 8 cell lines tested. Amrubicinol may contribute to the in vitro growth-inhibitory effect of amrubicin on these cells. The results suggest that amrubicinol plays an important role in the in vivo antitumor effect of amrubicin as an active metabolite.