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

Amrubicin encapsulated PLGA NPs inhibits the PI3K/AKT signaling pathway by activating PTEN and inducing apoptosis in TMZ-resistant Glioma

Glioblastoma (GBM) remains a challenging malignancy due to its aggressive nature and the lack of efficacious therapeutic interventions. Nanotechnology-based approaches exhibit promise in GBM treatment; however, the successful translation of these strategies from preclinical models to clinical settings is hindered by inefficient nanoparticle clearance from vital organs. Addressing this concern, we investigated the therapeutic potential of amrubicin (AMR) encapsulated within poly (lactic-co-glycolic acid) nanoparticles (AMR-PLGA-NPs) in combating temozolomide (TMZ) resistant GBM. The study demonstrated that AMR-PLGA-NPs exerted a pronounced inhibitory effect on the cellular viability and migratory capacity of TMZ-resistant GBM cells. Furthermore, these nanoparticles exhibited considerable efficacy in downregulating the PI3K/AKT signaling pathway, thereby inducing apoptosis specifically in TMZ-resistant glioma cells and glioma stem-like cells through the activation of PTEN. Notably,in vivoexperimentation revealed the ability of AMR-PLGA-NPs to traverse biological barriers within murine models. Collectively, these findings underscore the potential therapeutic utility of AMR-PLGA-NPs as a versatile nanoplatform for addressing the formidable challenges posed by GBM, particularly in mitigating drug resistance mechanisms. The study substantiates the stability and safety profile of AMR-PLGA-NPs, positioning them as a promising avenue for combating drug resistance in GBM therapeutics.

Salvage Chemotherapy in Patients with Previously Treated Thymic Carcinoma

Thymic carcinoma is a rare neoplasm, and it is difficult to achieve complete remission with systemic chemotherapy. In advanced or recurrent thymic carcinoma, platinum-based chemotherapy is chosen as the first-line setting; however, it remains unclear which regimen is better to improve its outcome. It remains unknown whether salvage chemotherapy should be administered to patients with platinum-based chemotherapy-refractory thymic carcinoma. Currently, several clinical studies have investigated the efficacy of second-line settings for advanced thymic carcinoma. As cytotoxic agents, S-1, amrubicin, pemetrexed, docetaxel, paclitaxel, and gemcitabine have been reported as prospective phase II studies or retrospective studies. The overall response rates (ORRs) of S-1, amrubicin, and pemetrexed were 25-50%, 11-44.4%, and 9-10%, respectively. Molecular targeting drugs, such as sunitinib, everolimus, and lenvatinib, also provide clinical effectiveness with tolerability after the failure of platinum-based regimens. Based on the results of the prospective phase II study, the ORR, median progression-free survival, and median overall survival were 16.6% and 5.6 months, respectively, in everolimus, 26% and 7.2 months, respectively, in sunitinib, and 38% and 9.3 months, respectively, in lenvatinib. Although it is difficult to compare each study, lenvatinib appears to be better in increasing efficacy as a second-line setting. However, each study had a small sample size, which may have biased the results of their studies. Further investigation is warranted to elucidate the therapeutic significance of salvage chemotherapy in advanced thymic carcinoma in a large-scale study.

Novel Anthracycline Utorubicin for Cancer Therapy

Novel anticancer compounds and their precision delivery systems are actively developed to create potent and well-tolerated anticancer therapeutics. Here, we report the synthesis of a novel anthracycline, Utorubicin (UTO), and its preclinical development as an anticancer payload for nanocarriers. Free UTO was significantly more toxic to cultured tumor cell lines than the clinically used anthracycline, doxorubicin. Nanoformulated UTO, encapsulated in polymeric nanovesicles (polymersomes, PS), reduced the viability of cultured malignant cells and this effect was potentiated by functionalization with a tumor-penetrating peptide (TPP). Systemic peptide-guided PS showed preferential accumulation in triple-negative breast tumor xenografts implanted in mice. At the same systemic UTO dose, the highest UTO accumulation in tumor tissue was seen for the TPP-targeted PS, followed by nontargeted PS, and free doxorubicin. Our study suggests potential applications for UTO in the treatment of malignant diseases and encourages further preclinical and clinical studies on UTO as a nanocarrier payload for precision cancer therapy.

Novel Anthracycline Utorubicin for Cancer Therapy

Novel anticancer compounds and their precision delivery systems are actively developed to create potent and well-tolerated anticancer therapeutics. Here, we report the synthesis of a novel anthracycline, Utorubicin (UTO), and its preclinical development as an anticancer payload for nanocarriers. Free UTO was significantly more toxic to cultured tumor cell lines than the clinically used anthracycline, doxorubicin. Nanoformulated UTO, encapsulated in polymeric nanovesicles (polymersomes, PS), reduced the viability of cultured malignant cells and this effect was potentiated by functionalization with a tumor-penetrating peptide (TPP). Systemic peptide-guided PS showed preferential accumulation in triple-negative breast tumor xenografts implanted in mice. At the same systemic UTO dose, the highest UTO accumulation in tumor tissue was seen for the TPP-targeted PS, followed by nontargeted PS, and free doxorubicin. Our study suggests potential applications for UTO in the treatment of malignant diseases and encourages further preclinical and clinical studies on UTO as a nanocarrier payload for precision cancer therapy.

DNA topoisomerases as molecular targets for anticancer drugs

The significant role of topoisomerases in the control of DNA chain topology has been confirmed in numerous research conducted worldwide. The prevalence of these enzymes, as well as the key importance of topoisomerase in the proper functioning of cells, have made them the target of many scientific studies conducted all over the world. This article is a comprehensive review of knowledge about topoisomerases and their inhibitors collected over the years. Studies on the structure-activity relationship and molecular docking are one of the key elements driving drug development. In addition to information on molecular targets, this article contains details on the structure-activity relationship of described classes of compounds. Moreover, the work also includes details about the structure of the compounds that drive the mode of action of topoisomerase inhibitors. Finally, selected topoisomerases inhibitors at the stage of clinical trials and their potential application in the chemotherapy of various cancers are described.

Phase II study of amrubicin plus erlotinib in previously treated, advanced non-small cell lung cancer with wild-type epidermal growth factor receptor (TORG1320)

Background Amrubicin (AMR) is a completely synthetic 9-aminoanthracycline and clinically active against non-small cell lung cancer (NSCLC). We conducted a phase I study of AMR and erlotinib (ERL) combination therapy in previously treated patients with advanced NSCLC and have already reported the safety and effectiveness. Methods We conducted a multi-center, single-arm phase II trial to evaluate the efficacy of AMR and ERL combination therapy in patients with previously treated, advanced NSCLC harboring wild-type EGFR, PS 0-1 and < 75 years of age. Patients were treated at 3-week intervals with AMR plus ERL. The primary endpoint was the PFS, and the secondary endpoints were the response rate (RR), disease control rate (DCR), overall survival (OS) and toxicity. The trough ERL concentration (C_trough) was measured as an exploratory study to analyze the relationship between the efficacy/safety and pharmacokinetics. Results From June 2013 to July 2016, 25 patients were enrolled in this trial. The PFS according to the central test was 3.6 months (95% confidence interval 2.1-5.1). The RR and DCR were 24.0% and 64.0%, respectively. We had no treatment-related deaths in this study. Conclusions The PFS of AMR and ERL combination therapy was superior to that of AMR monotherapy in the historical setting, but the primary endpoint was not met in this trial. In our study, the pharmacokinetic analysis showed that the C_trough of ERL was elevated with combination therapy. This combination therapy might be a viable treatment for previously treated NSCLC patients without a driver oncogene mutation. Clinical trial information UMIN 000010582.

Impact of Amrubicin Monotherapy as Second-Line Chemotherapy on Outcomes in Elderly Patients with Relapsed Extensive-Disease Small-Cell Lung Cancer

Purpose

Amrubicin (AMR) is an anticancer drug for patients with relapsed small-cell lung cancer (SCLC). However, the efficacy of AMR in elderly patients with relapsed SCLC after chemotherapy by carboplatin plus etoposide (CE) has not been sufficiently evaluated.

Patients and Methods

The medical records of patients with relapsed SCLC who received AMR as second-line chemotherapy were retrospectively reviewed, and their treatment outcomes were evaluated.

Results

Forty-one patients with a median age of 76 years were analyzed. The overall response rate was 26.8%. Median progression-free survival (PFS) and overall survival (OS) were 3.5 and 8.1 months, respectively. While the median PFS of 4.7 and 2.8 months in the sensitive relapse and the refractory relapse group differed significantly (P=0.043), respectively, the median OS of 10.7 and 6.8 months in the respective relapse groups did not indicate a statistically significant difference (P=0.24). The median PFS in a group with a modified Glasgow prognostic score (mGPS) of 0 and a group with a mGPS 1 or 2 were 4.5 and 1.6 months (P=0.052), respectively, and the median OS in the respective mGPS groups were 10.7 and 4.4 months (P=0.034). Multivariate analysis identified good performance status, limited disease, and mGPS 0 as favorable independent predictors of PFS and OS of AMR monotherapy. Grade 3 or higher neutropenia was observed in 23 patients (56%), and febrile neutropenia was observed in nine patients (22%). Non-hematological toxic effects were relatively mild, and pneumonitis and treatment-related deaths were not observed.

Conclusion

AMR is an effective and feasible regimen for elderly patients with relapsed SCLC after CE therapy.

Amrubicin in previously treated patients with malignant pleural mesothelioma: A phase II study

Background

The aim of this study was to assess the efficacy and safety of amrubicin for previously treated malignant pleural mesothelioma.

Methods

The eligibility criteria were: previously treated unresectable malignant pleural mesothelioma; performance status 0–1; age ≤ 75; adequate hematological, hepatic, and renal function. The patients were injected with 35 mg/m² amrubicin on days one, two, and three every 3–4 weeks. The planned number of patients was 32.

Results

The study was terminated due to delay in enrollment and 10 patients were subsequently enrolled (nine males and one female; median age 67 [range 49–73]), of which four had epithelioid tumors, three had sarcomatoid tumors and three had biphasic tumors, respectively. According to the International Mesothelioma Interest Group (IMIG), one, four, and four patients had stage II, III, and IV, respectively, and one had postoperative recurrence. There was one (10%) partial response, four (40%) had stable disease, and five (50%) patients exhibited disease progression. The overall response and disease control rates were 10% (95% CI: 0.3–44.5%) and 60% (95% CI: 26.2–87.8%), respectively. The median progression‐free survival time was 1.6 months. The median overall survival time was 6.6 months, and the one‐, two‐, and three‐year survival rates were 23%, 23%, and 0%, respectively. The observed grade 3 or 4 toxicities included neutropenia in six (60%) patients; leukopenia in five (50%) patients; and febrile neutropenia, thrombocytopenia, anemia, and pneumonia in one (10%) patient each.

Conclusions

There was not enough data to evaluate the efficacy because the study was terminated early. However, amrubicin showed limited activity and

acceptable toxicities when used in previously treated malignant pleural mesothelioma patients.

Clinical significance of topoisomerase-II expression in patients with advanced non-small cell lung cancer treated with amrubicin

Background

Amrubicin chemotherapy is a treatment option for patients with non‐small cell lung cancer (NSCLC) after third‐line treatment in Japan. Although topoisomerase‐II (Topo‐II), a target of amrubicin, has been reported to be a prognostic or predictive marker for chemosensitivity and clinical outcomes in various types of malignancies, its effects in the Japanese population remain unknown.

Methods

Data regarding 44 patients with advanced NSCLC treated with amrubicin between April 2004 and May 2014 were retrospectively analyzed. We evaluated the expression levels of Topo‐II by immunohistochemical staining of tumor specimens obtained via biopsy or surgical resection.

Results

The majority of enrolled patients were men (68%) with a median age of 67 (range, 43–78) years. The most common histological type was adenocarcinoma (70%). High Topo‐II expression was observed in 13 (30%) of the 44 patients. The median progression‐free survival and overall survival (OS) durations were 1.8 and 8.8 months, respectively. While there was no significant association between Topo‐II expression and progression‐free survival, patients with low Topo‐II expression had significantly longer OS than did those with high Topo‐II expression. Good performance status and low expression of Topo‐II were all significantly associated with a favorable OS.

Conclusion

Low expression of Topo‐II was identified as an independent prognostic factor for longer survival in patients with NSCLC receiving amrubicin, a Topo‐II inhibitor.

Key points

Dose escalation study of amrubicin and cisplatin with concurrent thoracic radiotherapy for limited-disease small cell lung cancer

BACKGROUND

Amrubicin and cisplatin is one of the active regimens used to treat patients with extensive-disease (ED)-small cell lung cancer (SCLC), whereas combined therapy involving chemotherapy and concurrent thoracic radiotherapy is the standard treatment for limited-disease (LD)-SCLC.

PURPOSE

This study aimed to determine the maximum tolerated dose (MTD) and dose-limiting toxicities (DLT) of amrubicin and cisplatin with concurrent thoracic radiotherapy (TRT) for LD-SCLC.

PATIENTS AND METHODS

Patients that fulfilled the following eligibility criteria were enrolled: being aged ≤ 75 years and chemotherapy-naïve and having a performance status (PS) of 0-1, LD-SCLC, and adequate organ function. The patients received escalating doses of amrubicin on days 1, 2, and 3, and a fixed 60-mg/m² dose of cisplatin on day 1. Four cycles of chemotherapy were administered, with each cycle lasting 4 weeks. TRT involving 2 Gy/day, once daily, commenced on day 2 of the first cycle of chemotherapy. The initial dose of amrubicin was 20 mg/m² (level 1), and the dose was escalated to 25 mg/m² (level 2) and then 30 mg/m² (level 3).

RESULTS

Eight patients from three institutions were enrolled at three dose levels. The patients' characteristics were as follows: male/female: 3/5; median age (range): 68.5 (60-73); PS 0/1: 4/4; stage IIIA/IIIB disease: 3/5. Both level 3 patients experienced DLT (grade 4 neutropenia and/or leukopenia lasting > 4 days). Level 3 was defined as the MTD, and level 2 was recommended as the dose for this regimen. Seven patients exhibited partial responses, and 1 displayed progressive disease (response rate: 88%). The median progression-free survival and overall survival periods were 11.1 and 39.5 months, respectively. No treatment-related deaths occurred.

CONCLUSIONS

When this regimen was combined with TRT for LD-SCLC, the MTD was 30 mg/m² for amrubicin and 60 mg/m² for cisplatin. In addition, neutropenia and leukopenia were DLT, and doses of 25 mg/m² for amrubicin and 60 mg/m² for cisplatin are recommended for this regimen.

Efficacy and Safety of Amrubicin in Non-Small-Cell Lung Cancer Patients Beyond Third-Line Therapy

BACKGROUND

There are no standard cytotoxic treatments for non-small-cell lung cancer (NSCLC) patients beyond third-line therapy. The purpose of this study was to evaluate the efficacy and safety of amrubicin in pretreated NSCLC patients.

METHODS

The records of NSCLC patients who received amrubicin monotherapy as a third or later line of chemotherapy at Shizuoka General Hospital between April 2007 and March 2015 were retrospectively reviewed. Tumor response was evaluated according to the Response Evaluation Criteria in Solid Tumors version 1.1. Toxicities were evaluated according to the Common Terminology Criteria for Adverse Events version 3.0.

RESULTS

Overall, 69 patients were enrolled in this study; 16 patients were female and the median age was 67 years. The median number of treatment cycles was 3. The response rate was 7.2%, and the disease control rate was 63.8%. The median progression-free survival was 2.8 months. The median overall survival was 7.7 months. Hematological toxicities of ≥ grade 3 included leukopenia (59.4%) and neutropenia (62.3%). Non-hematological toxicities of ≥ grade 2 included anorexia (27.5%) and fatigue (24.6%).

CONCLUSION

Although hematological toxicities were severe, these results suggested that amrubicin in NSCLC patients beyond third-line therapy shows sufficient clinical benefit.

Amrubicin monotherapy for elderly patients with relapsed extensive-disease small-cell lung cancer: A retrospective study

Background

Previous studies have shown amrubicin (AMR) to be an effective second‐line treatment option for small‐cell lung cancer (SCLC). However, the efficacy of AMR in elderly patients with relapsed SCLC has not been sufficiently evaluated.

Methods

The medical records of elderly patients with relapsed SCLC who received AMR as second‐line chemotherapy were retrospectively reviewed, and their treatment outcomes were evaluated.

Results

Thirty‐one patients with a median age of 72 years (22 patients with sensitive relapse and 9 with refractory relapse) were analyzed. The median number of treatment cycles was four (range: 1–10), and the response rate was 29%. The median progression‐free survival (PFS) and overall survival (OS) were 5.4 and 11.6 months, respectively. The OS of 22 patients who received third‐line chemotherapy was 15.5 months. The PFS (6.2 vs. 3.2 months; P = 0.002) and OS (14.8 vs. 5.7 months; P = 0.004) were significantly longer in patients with sensitive relapse than those with refractory relapse. The frequency of grade 3 or higher neutropenia was high (n = 18, 58%), while febrile neutropenia was only observed in five patients (16%). Non‐hematological toxic effects were relatively mild, and pneumonitis and treatment‐related deaths were not observed.

Conclusion

AMR may be a feasible and effective regimen for elderly patients with relapsed SCLC.

Comparison of carboplatin plus etoposide with amrubicin monotherapy for extensive-disease small cell lung cancer in the elderly and patients with poor performance status

BACKGROUND

Carboplatin plus etoposide (CE) is a standard treatment for elderly patients with extensive-disease small cell lung cancer (ED-SCLC). However, amrubicin monotherapy (AMR) may be a feasible alternative. We compared the efficacies and safety profiles of CE and AMR for ED-SCLC in elderly patients and chemotherapy-naive patients with poor performance status (PS).

METHODS

The records of SCLC patients who received CE or AMR as first-line chemotherapy were retrospectively reviewed and their treatment outcomes evaluated.

RESULTS

Eighty-four patients (median age 72 years; 42 each received CR and AMR) were analyzed; 34 patients had a PS score of 2. There were no significant differences in patient characteristics between the treatment groups. The median progression-free survival rates of patients in the CE and AMR groups were 5.8 and 4.8 months, respectively (P = 0.04); overall survival was 14.0 and 8.5 months, respectively (P = 0.089). Twenty-three CE group patients received AMR as second-line chemotherapy; their median overall survival from first-line chemotherapy was 18.5 months. Grade 3 or higher neutropenia occurred more frequently in patients treated with AMR (64% vs. 40%; P = 0.02), as did febrile neutropenia (14% vs. 7%).

CONCLUSIONS

CE remains a suitable first-line treatment for ED-SCLC in elderly patients or those with poor PS in comparison with AMR.

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.

A retrospective study of amrubicin monotherapy for the treatment of relapsed small cell lung cancer in elderly patients

Purpose

Amrubicin is one of the most active chemotherapeutic drugs for small cell lung cancer (SCLC). Previous studies reported its effectiveness and severe hematological toxicity. However, the efficacy of amrubicin monotherapy in elderly patients with SCLC has not been described. The objective of this study was to investigate the feasibility of amrubicin monotherapy in elderly patients and its efficacy for relapsed SCLC.

Methods

A retrospective cohort study design was used. We retrospectively evaluated the clinical effects and adverse events of amrubicin treatment in elderly (≥70 years) SCLC patients with relapsed SCLC.

Results

Between November 2003 and September 2015, 86 patients (aged ≥70 years) received amrubicin monotherapy for relapsed SCLC at four institutions. There were 42 cases of sensitive relapse (S) and 44 of refractory relapse (R). S cases with median age of 75 years (range 70–85 years) and R cases with median age of 74 years (range 70–84 years) were included in our analysis. The median number of treatment cycles was three (range 1–9), and the response rate was 33.7% (40.5% in the S and 27.2% in the R cases). Median progression-free survival time was 4.0 months in the S and 2.7 months in the R patients (p = 0.013). Median survival time from the start of amrubicin therapy was 7.6 months in the S and 5.5 months in the R cases (p = 0.26). The frequencies of grade ≥3 hematological toxicities were as follows: leukopenia, 60.4%; neutropenia, 74.4%; anemia, 11.6%; thrombocytopenia, 16.2%; and febrile neutropenia, 17.4%. Treatment-related death was observed in one patient.

Conclusion

Although hematological toxicities, particularly neutropenia, were severe, amrubicin showed favorable efficacy, not only in the S but also in the R cases, as shown in previous studies. Amrubicin could be a preferable standard treatment in elderly patients with relapsed SCLC. These results warrant further evaluation of amrubicin in elderly patients with relapsed SCLC by a prospective trial.

Electronic supplementary material

The online version of this article (doi:10.1007/s00280-017-3403-9) contains supplementary material, which is available to authorized users.

Phase II study of Amrubicin monotherapy in elderly or poor-risk patients with extensive disease of small cell lung cancer

Background Previous study indicated that an optional anti-cancer drug for the treatment of small-cell lung cancer (SCLC) is amrubicin. However, no prospective studies have evaluated amrubicin in chemo-naive elderly or poor-risk patients with SCLC. Therefore, this study aimed to evaluate the efficacy of amrubicin as first-line chemotherapy for elderly or poor-risk patients with extensive-disease SCLC (ES-SCLC). Methods Patients with chemotherapy-naive ES-SCLC received multiple cycles of 40 mg/m² amrubicin for 3 consecutive days every 21 days. The primary endpoint was the overall response rate (ORR), and the secondary endpoints were progression-free survival (PFS), overall survival (OS), and safety. Results Between March 2011 and August 2015, 36 patients were enrolled in this study. Each patient received a median of four treatment cycles (range, 1-6 cycles). ORR was 52.8% [95% confidence interval (CI), 37-69%]. The median PFS and OS periods were 5.0 months (95% CI, 3.4-6.6 months) and 9.4 months (95% CI, 5.2-13.6 months), respectively. Neutropenia was the most common grade 3 or 4 adverse event (69.4%), with febrile neutropenia developing in 13.9% of patients. No treatment-related death occurred. At the time of starting second-line chemotherapy, 19 of 22 patients (86%) had significantly improved or maintained their performance status (PS) relative to their PS at the time of starting amrubicin monotherapy as first-line chemotherapy (P = 0.027). Conclusions The results of the present study suggest that amrubicin could be considered as a viable treatment option for chemotherapy-naive elderly or poor-risk patients with ES-SCLC (Clinical trial registration number: UMIN000011055 www.clinicaltrials.gov ).

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.

Phase I and pharmacokinetic study of erlotinib administered in combination with amrubicin in patients with previously treated, advanced non-small cell lung cancer

OBJECTIVES

We conducted a phase I trial of erlotinib, an epidermal growth factor receptor tyrosine kinase inhibitor, combined with amrubicin, a topoisomerase II inhibitor. The aim was to determine the maximum tolerated dose, the dose-limiting toxicities (DLTs), and the pharmacokinetics of this combination in patients with non-small cell lung cancer who had received previous chemotherapy.

METHODS

A total of 9 patients with stage IV disease were treated at 3-week intervals with erlotinib once daily on days 1 through 21 plus a 5-minute intravenous injection of amrubicin on days 1 through 3.

RESULTS

The dose levels evaluated were erlotinib (mg/body)/amrubicin (mg/m): 100/30 (n=3), 100/35 (n=3), and 150/30 (n=3). The maximum tolerated dose of erlotinib and amrubicin was 100 mg/body and 35 mg/m because 2 of the 3 patients experienced DLTs during the first cycle of treatment at the third dose level of 150 mg/body and 30 mg/m. Cessation of erlotinib administration for 8 days because of grade 3 leukopenia and grade 3 skin infection (erysipelas) were the DLTs. No drug-drug interactions between erlotinib and amrubicin were observed in this study. The overall response rate was 33%, including 3 partial responses, in the 9 patients. The median progression-free survival for all patients was quite long, 11.3 months, and the median overall survival has not yet been reached.

CONCLUSIONS

Combined erlotinib plus amrubicin therapy seems to be highly effective, with acceptable toxicity, against non-small cell lung cancer. The recommended dose for phase II studies was erlotinib 100 mg once daily on days 1 through 21, and amrubicin 35 mg/m on days 1 through 3 administered every 21 days.

Amrubicin as second- or third-line treatment for women with metastatic HER2-negative breast cancer: a Sarah Cannon Research Institute phase 1/2 trial

Amrubicin is a synthetic anthracycline which has been shown in preclinical studies to have broad-spectrum anti-tumor activity and a lower potential for cardiotoxicity as compared to doxorubicin. We conducted a phase 1/2 trial of single-agent amrubicin as second- or third-line treatment for women with metastatic breast cancer. Women with metastatic HER2-negative breast cancer who had normal cardiac function and measurable disease, received intravenous (IV) amrubicin every 3 weeks. Prophylactic treatment with granulocyte colony-stimulating factors (G-CSFs) was recommended. Escalating amrubicin doses were administered in a 3 + 3 design in the phase 1 portion to determine the maximum tolerated dose. Achievement of a median PFS ≥4.5 months would warrant further development of amrubicin in this setting. Seventy-eight women (median age 58 years) were treated (phase 1, 15 patients; phase 2, 63 patients). An amrubicin dose of 110 mg/m(2) every 3 weeks was selected as the phase 2 dose, and 66 patients were treated. Twelve of 66 patients (18%) achieved objective response, and the clinical benefit rate was 42%. Median PFS was 4 months (95% CI 2.5, 5.8). Neutropenia was the most common grade 3/4 toxicity, observed in 29 patients (44%). One patient experienced an asymptomatic transient left ventricular ejection fraction decline (grade 3). Although the study did not meet the predefined PFS, amrubicin was well tolerated at 110 mg/m(2) IV when administered every 3 weeks with prophylactic G-CSF, and was an active second- or third-line treatment for metastatic HER2-negative breast cancer.

The role of anthracyclines in small cell lung cancer

Small cell lung cancer (SCLC) represents the 15% of the totally of lung cancer. The percentage of cases in women is arising due to the differences in smoking patterns; it occurs almost exclusively in smokers and appears to be most common in heavy smokers. The stage of disease at presentation is the most important prognostic factor in patients with SCLC; for patients with extended stage disease, the median survival is around 10 months, and the five-year survival rate is 1 to 2 percent. The standard regimen for patients with extensive disease is cisplatin based chemotherapy. Second line chemotherapy is generally less effective than the initial treatment but it can provide significant palliation for many patients. We make a review here of the different options of second line chemotherapy and the role of anthracyclines in it.

Synergistic cell growth inhibition by the combination of amrubicin and Akt-suppressing agents in K-ras mutation-harboring lung adenocarcinoma cells: implication of EGFR tyrosine kinase inhibitors

Previously we showed that Akt-suppressing agents, combined with amrubicin, synergistically inhibited the growth of small cell lung cancer cells. The combined effects of chemotherapeutic agents and Akt-suppressing agents, including epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors, were evaluated in A549 lung adenocarcinoma cells harboring K-ras mutation and wild-type EGFR. Only amrubicin and not other chemotherapeutics (cisplatin, pemetrexed and paclitaxel) synergistically inhibited cell growth when combined with an Akt inhibitor, LY294002. The combination of amrubicin and LY294002 enhanced Annexin V binding to cells. A non-specific tyrosine kinase inhibitor, genistein, suppressed Akt and showed synergistic interaction in combination with amrubicin. Two EGFR tyrosine kinase inhibitors (EGFR-TKIs), gefitinib and erlotinib, suppressed Akt activity at clinically achievable concentrations and demonstrated synergism when combined with amrubicin. The suppression of K-ras expression by siRNA interfered with this synergism and inhibited both EGFR and Akt activity in A549 cells. In Ma10 cells, which harbor wild-type EGFR and K-ras, EGFR-TKIs neither suppressed Akt activity nor exhibited such synergism when combined with amrubicin. We concluded that the synergism by the combination of EGFR-TKI and amrubicin is attributable, at least partially, to K-ras mutation in A549 cells. The combination of EGFR-TKI and amrubicin may be a promising treatment for lung cancer with wild-type EGFR and K-ras mutation.

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.

Amrubicin as second-line and beyond treatment for platinum-refractory advanced thymic carcinoma

OBJECTIVE

Thymic carcinoma is a rare mediastinal neoplasm, and the prognosis of patients with advanced thymic carcinoma is poor. No standard chemotherapeutic regimen has yet been established for the disease. This is the first report to evaluate the role of amrubicin, a novel anthracycline anticancer drug, in second-line and beyond treatment for patients with platinum-refractory advanced thymic carcinoma.

METHODS

This study was a review of thymic carcinoma patients who had received amrubicin monotherapy between June 2003 and December 2011 for the progression of disease previously treated with platinum-based chemotherapy. Amrubicin was administered at 35 or 40 mg/m(2) for three consecutive days every 3 weeks, until progression.

RESULTS

Nine patients with recurrent thymic carcinoma were registered. Their median age was 61 years (range 45-72), and the patients included five males and four females. All nine patients had Masaoka's Stage IVb disease. There were three squamous cell carcinomas, one adenocarcinoma, one small-cell carcinoma and two other histological types. The mean number of chemotherapy cycles was five (range 2-13). Grade 3 or higher toxicities included mainly neutropenia (55.5%), anemia (25.0%) and febrile neutropenia (11.1%). No treatment-related deaths were observed. The response rate was 44.4% (95% confidence interval: 19-73). The median progression-free survival after the amrubicin monotherapy was 4.9 months, while the median overall survival was 6.4 months.

CONCLUSIONS

Single-agent amrubicin was found to be potentially useful as second-line and beyond chemotherapy for patients with advanced thymic carcinoma. Further multi-institutional prospective studies are warranted.

Dose escalation and feasibility study of amrubicin combined with cisplatin in previously untreated patients with advanced non-small cell lung cancer

OBJECTIVES

Cisplatin is a key drug used in the treatment of non-small cell lung cancer (NSCLC), and amrubicin is one of the new active agents for NSCLC. The objective of this study was to determine the recommended dose (RD) of amrubicin in combination with a fixed dose of cisplatin, and to assess the toxicity profile and feasibility of this regimen.

METHODS

We conducted a dose escalation study of amrubicin and cisplatin in previously untreated patients with stage IIIB or IV NSCLC. Dose level 1 of amrubicin was 30 mg/m on days 1 to 3 and level 2 was 35 mg/m. Cisplatin was administered at a fixed dose of 80 mg/m on day 1. Chemotherapy was given in a 3-week cycle.

RESULTS

Twenty patients were enrolled. Dose-limiting toxicities were neutropenia, febrile neutropenia, thrombocytopenia, and creatinine elevation. Level 1 (30 mg/m) was determined to be the RD, and 35 mg/m exceeded the RD. In 17 patients treated with the RD, the overall response rate was 41.2% (95% confidence interval, 17.7-64.7) and the median survival time was 16.4 months (95% confidence interval, 13.1-19.5).

CONCLUSIONS

This amrubicin and cisplatin regimen may be feasible and promising against advanced NSCLC. The efficacy and safety of this regimen should be confirmed in a phase II study.

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.

Risk factors for predicting severe neutropenia induced by amrubicin in patients with advanced lung cancer

BACKGROUND

Neutropenia is one of the most frequent and dose-limiting toxicities in amrubicin (AMR) therapy. However, the predictive factors for the development of severe neutropenia in AMR therapy remain unknown.

METHODS

The subjects were 61 advanced lung cancer patients treated with AMR monotherapy. All data were retrospectively collected from the electronic medical record system. A stepwise logistic regression analysis was performed to identify risk factors for grade 3-4 neutropenia.

RESULTS

Of a total 61 patients, 50 were male and 11 were female. The median dose of AMR was 35.0 mg/m(2). The incidence of grade 3-4 neutropenia during the first course was 62%. In multivariate analysis, female gender (OR = 6.68; 95% CI 1.01-134.15; p = 0.049), higher AMR doses (40 mg/m(2) or more) (OR = 5.98; 95% CI 1.77-23.74; p = 0.003), and lower hematocrit values (OR = 2.04 per 5% decrease; 95% CI 1.04-4.38; p = 0.036) were significantly associated with severe neutropenia induced by AMR.

CONCLUSION

The present results suggest that female gender, higher doses of AMR, and lower baseline hematocrit values are predictive factors associated with severe neutropenia induced by AMR in patients with advanced lung cancer. Patients who have these predictive factors should be monitored carefully and considered for early granulocyte colony-stimulating factor support.

Pharmacokinetic characterization of amrubicin cardiac safety in an ex vivo human myocardial strip model. II. Amrubicin shows metabolic advantages over doxorubicin and epirubicin

Anthracycline-related cardiotoxicity correlates with cardiac anthracycline accumulation and bioactivation to secondary alcohol metabolites or reactive oxygen species (ROS), such as superoxide anion (O₂·⁻) and hydrogen peroxide H₂O₂). We reported that in an ex vivo human myocardial strip model, 3 or 10 μM amrubicin [(7S,9S)-9-acetyl-9-amino-7-[(2-deoxy-β-D-erythro-pentopyranosyl)oxy]-7,8,9,10-tetrahydro-6,11-dihydroxy-5,12-napthacenedione hydrochloride] accumulated to a lower level compared with equimolar doxorubicin or epirubicin (J Pharmacol Exp Ther 341:464-473, 2012). We have characterized how amrubicin converted to ROS or secondary alcohol metabolite in comparison with doxorubicin (that formed both toxic species) or epirubicin (that lacked ROS formation and showed an impaired conversion to alcohol metabolite). Amrubicin and doxorubicin partitioned to mitochondria and caused similar elevations of H₂O₂, but the mechanisms of H₂O₂ formation were different. Amrubicin produced H₂O₂ by enzymatic reduction-oxidation of its quinone moiety, whereas doxorubicin acted by inducing mitochondrial uncoupling. Moreover, mitochondrial aconitase assays showed that 3 μM amrubicin caused an O₂·⁻-dependent reversible inactivation, whereas doxorubicin always caused an irreversible inactivation. Low concentrations of amrubicin therefore proved similar to epirubicin in sparing mitochondrial aconitase from irreversible inactivation. The soluble fraction of human myocardial strips converted doxorubicin and epirubicin to secondary alcohol metabolites that irreversibly inactivated cytoplasmic aconitase; in contrast, strips exposed to amrubicin failed to generate its secondary alcohol metabolite, amrubicinol, and only occasionally exhibited an irreversible inactivation of cytoplasmic aconitase. This was caused by competing pathways that favored formation and complete or near-to-complete elimination of 9-deaminoamrubicinol. These results characterize amrubicin metabolic advantages over doxorubicin and epirubicin, which may correlate with amrubicin cardiac safety in preclinical or clinical settings.

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.

Update on new drugs in small cell lung cancer

INTRODUCTION

Small cell lung cancer (SCLC) will account for 25,000 to 32,000 new lung cancer cases in the USA in 2010. Current treatmenta pproaches include platinum-based chemotherapy and etoposide with or without radiation therapy depending on stage and performance status. Five-year survival is approximately 25% for patients with limited stage disease and 1 -- 2% for patients with extensive stage disease and has noti mproved in almost two decades.

AREAS COVERED

This article reviews the results of recent clinical trials that have evaluated targeted agents and novel cytotoxic agents alone or in combination with standard chemotherapy in the treatment of patients with SCLC.

EXPERT OPINION

The lack of a targeted approach to the treatment of patients with SCLC has led investigators to evaluate a multitude of agents with overwhelmingly negative results. A more systematic approach to clinical trials in patients is needed to improve outcomes for patients with this disease.

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.

Randomized Phase II Trial of Single-Agent Amrubicin or Topotecan as Second-Line Treatment in Patients With Small-Cell Lung Cancer Sensitive to First-Line Platinum-Based Chemotherapy

Purpose

This phase II study evaluated the safety and efficacy of single-agent amrubicin versus topotecan in patients with small-cell lung cancer (SCLC) sensitive to first-line platinum-based chemotherapy.

Patients and Methods

Patients were randomly assigned 2:1 to amrubicin (40 mg/m2/d in a 5-minute intravenous [IV] infusion, days 1 through 3, every 21 days) or topotecan (1.5 mg/m2/d in a 30-minute IV infusion, days 1 through 5, every 21 days). The primary efficacy end point was overall response rate (ORR) for amrubicin. Secondary end points included time to progression, median progression-free survival (PFS), and median overall survival (OS).

Results

Of 76 patients enrolled, 50 patients were randomly assigned to amrubicin, and 26 patients were randomly assigned to topotecan. Amrubicin treatment resulted in a significantly higher ORR than topotecan (44% v 15%; P = .021). Median PFS and median OS were 4.5 months and 9.2 months with amrubicin and 3.3 months and 7.6 months with topotecan, respectively. Tolerability was similar with both agents. However, grade 3 or worse neutropenia and thrombocytopenia seemed to be more frequent in the topotecan group as compared with the amrubicin group (78% and 61% v 61% and 39%, respectively).

Conclusion

Amrubicin shows promising activity, with an ORR of 44% compared with an ORR of 15% for topotecan as second-line treatment in patients with SCLC sensitive to first-line platinum-based chemotherapy. In addition, the safety profiles were comparable; however, a trend was noted for more frequent grade 3 or worse neutropenia and thrombocytopenia in the topotecan group as compared with the amrubicin group. Additional studies are ongoing.

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.

Efficacy and safety of amrubicin hydrochloride for treatment of relapsed small cell lung cancer

Long-term survival is quite uncommon in refractory small cell lung cancer (SCLC) patients, with less than 25% of patients with limited-stage disease and 1%-2% of patients with extensive-stage disease remaining alive at five years. Recent clinical studies have demonstrated the promising efficacy of amrubicin for patients with relapsed SCLC. This review presents the results of clinical studies showing the efficacy and safety of amrubicin for the treatment of relapsed SCLC. Amrubicin is a synthetic anthracycline agent with a similar structure to doxorubicin, in which the hydroxyl group at position 9 in amrubicin is replaced by an amino group to enhance efficacy. It is converted to an active metabolite, amrubicinol, which is 5-54 times more active than amrubicin. Amrubicin and amrubicinol are inhibitors of DNA topoisomerase II, exerting their cytotoxic effects by stabilizing a topoisomerase II-mediated cleavable complex. The toxicity of amrubicin is similar to that of doxorubicin, although amrubicin shows almost no cardiotoxicity. In the relevant trials, amrubicin was administered intravenously at a dose of 35-40 mg/m(2) on days 1-3 every three weeks. The response rate was 34%-52% and median survival times were 8.1-12.0 months. Common hematologic toxicities included neutropenia, leucopenia, anemia, thrombocytopenia, and febrile neutropenia. Nonhematologic adverse events included Grade 3-4 anorexia, asthenia, hyponatremia, and nausea. The results of the studies which demonstrated the efficacy of monotherapy for relapsed SCLC involved mainly Japanese patients. Therefore, it is necessary to conduct more clinical studies in non-Japanese patients to confirm the efficacy of amrubicin.

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.

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.

Amrubicin for treating elderly and poor-risk patients with small-cell lung cancer

BACKGROUND

This study was conducted to evaluate the efficacy of amrubicin as first-line chemotherapy for elderly and poor-risk patients with extensive-disease small-cell lung cancer (ED-SCLC).

METHODS

Untreated SCLC patients who were >75 years of age or had a performance status of 2 or more were eligible. Amrubicin (35 or 40 mg/m(2) on days 1-3 every 3 weeks) was administered.

RESULTS

Between January 2003 and May 2009, 27 patients were evaluated. The median number of treatment cycles was 4 (1-6). Grade 3 or 4 hematologic toxicities comprised neutropenia (63%), leukopenia (56%), thrombocytopenia (15%), and anemia (19%). Febrile neutropenia was observed in four (15%) patients. No treatment-related deaths occurred. The nonhematologic toxicities were mild. The overall response rate was 70%. Progression-free survival, median survival time, and the 1-year survival rate were 6.6 months, 9.3 months, and 30%, respectively. The 40 mg/m(2) dose was feasible and had a tendency to be more effective than the 35 mg/m(2) dose.

CONCLUSIONS

Amrubicin exhibits activity and acceptable toxicities for elderly and poor-risk patients with ED-SCLC in the first-line treatment setting.

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.

Phase II trial of amrubicin for second-line treatment of advanced non-small cell lung cancer: results of the West Japan Thoracic Oncology Group trial (WJTOG0401)

BACKGROUND

Amrubicin is a synthetic anthracycline drug that is a potent inhibitor of topoisomerase II. We have performed a multicenter phase II trial to evaluate the efficacy and safety of amrubicin for patients with previously treated non-small cell lung cancer (NSCLC).

METHODS

Patients with advanced NSCLC who experienced disease recurrence after one platinum-based chemotherapy regimen were eligible for enrollment in the study. Amrubicin was administered by intravenous injection at a dose of 40 mg/m2 on 3 consecutive days every 3 weeks.

RESULTS

Sixty-one enrolled patients received a total of 192 treatment cycles (median, 2; range, 1-15). Response was as follows: complete response, 0; partial response, seven (11.5%); stable disease, 20 (32.8%); and progressive disease, 34 (55.7%). Median progression-free survival was 1.8 months, whereas median overall survival was 8.5 months, and the 1-year survival rate was 32%. Hematologic toxicities of grade 3 or 4 included neutropenia (82.0%), leukopenia (73.8%), thrombocytopenia (24.6%), and anemia (27.9%). Febrile neutropenia occurred in 18 patients (29.5%). One treatment-related death due to infection was observed. Nonhematologic toxicities were mild.

CONCLUSIONS

Amrubicin is a possible alternative for second-line treatment of advanced NSCLC, although a relevant hematological toxicity is significant, especially with a febrile neutropenia.

Plasma concentration of amrubicinol in plateau phase in patients treated for 3 days with amrubicin is correlated with hematological toxicities

Amrubicinol (AMR-OH) is an active metabolite of amrubicin (AMR), a novel synthetic 9-aminoanthracycline derivative. The time-concentration profile of AMR-OH exhibits a continuous long plateau slope in the terminal phase. To determine the relationships between the steady-state plasma concentration of AMR-OH and treatment effects and toxicities associated with AMR therapy, we carried out a pharmacokinetic/pharmacodynamic study in patients treated with AMR alone or the combination of AMR+cisplatin (CDDP). AMR was given at a dose of 30 or 40 mg/m(2) on days 1-3. Plasma samples were collected 24 h after the third injection (day 4). Plasma concentrations of AMR-OH or total CDDP were determined by a high-performance liquid chromatography or an atomic absorption spectrometry. Percent change in neutrophil count (dANC) and the plasma concentration of AMR-OH were evaluated using a sigmoid E(max) model. A total of 35 patients were enrolled. Significant relationships were observed between AMR-OH on day 4 and the toxicity grades of leukopenia, neutropenia, and anemia (P=0.018, P=0.012, and P=0.025, respectively). Thrombocytopenia grade exhibited a tendency toward relationship with AMR-OH on day 4 (P=0.081). The plasma concentration of AMR-OH on day 4 was positively correlated with dANC in the group of all patients, as well as in patients treated with AMR alone and in patients coadministered with CDDP. In conclusion, the plasma concentration of AMR-OH on day 4 was correlated with hematological toxicities in patients treated with AMR. The assessment of plasma concentration of AMR-OH at one timepoint might enable the prediction of hematological toxicities.