Dose-intensive therapy in small cell lung cancer

Thanatop: A Novel 5-Nitrofuran that Is a Highly Active, Cell-Permeable Inhibitor of Topoisomerase II

A series of nitrofuran-based compounds were identified as inhibitors of estrogen signaling in a cell-based, high-throughput screen of a diverse library of small molecules. These highly related compounds were subsequently found to inhibit topoisomerase II in vitro at concentrations similar to that required for the inhibition of estrogen signaling in cells. The most potent nitrofuran discovered is approximately 10-fold more active than etoposide phosphate, a topoisomerase II inhibitor in clinical use. The nitrofurans also inhibit topoisomerase I activity, with approximately 20-fold less activity. Moreover, the nitrofurans, in contrast to etoposide, induce a profound cell cycle arrest in the G(0)-G(1) phase of the cell cycle, do not induce double-stranded DNA breaks, are not substrates for multidrug resistance protein-1 export from the cell, and are amenable to synthetic development. In addition, the nitrofurans synergize with etoposide phosphate in cell killing. Clonogenic assays done on a panel of human tumors maintained ex vivo in nude mice show that the most active compound identified in the screen is selective against tumors compared with normal hematopoietic stem cells. However, this compound had only moderate activity in a mouse xenograft model. This novel class of topoisomerase II inhibitor may provide additional chemotherapeutic strategies for the development of cytotoxic agents with proven clinical utility.

Progress in the therapy of small cell lung cancer

Small cell lung cancer (SCLC) accounts for approximately 14% of all cases of lung cancer. Combination chemotherapy is the most effective treatment modality for SCLC and recently, several new active drugs have emerged. Combinations of platinum agents with CPT-11 or gemcitabine have been successfully compared in phase III trials against the cisplatin/etoposide standard. Modest improvements in the outcome of patients with SCLC have been noted over the last two decades. Thoracic irradiation given concurrently with chemotherapy improves survival compared with sequential chemotherapy and radiation, but this approach is associated with more toxicity. Moreover, the optimal doses and fractionation of thoracic irradiation remain to be determined. Three-dimensional treatment planning is under investigation. Prophylactic cranial irradiation (PCI) has established a role in the management of patients who have achieved a complete response to the initial therapy. Novel molecular targeted therapies are among the strategies currently being investigated in SCLC.

Recent advances in management of small-cell lung cancer

Small-cell lung cancer (SCLC) is a smoking-related disease with a poor prognosis. While SCLC is usually initially sensitive to chemotherapy and radiotherapy, responses are rarely long lasting. Frustratingly, most patients ultimately relapse, often with increasingly treatment resistant disease. Many strategies have been developed in an attempt to improve treatment outcomes, which have plateaued since the introduction of combination chemotherapy in the 1980s. These include trials of maintenance therapy, and dose intensification, the latter by means of increasing dose density, growth factor support and high dose chemotherapy with autologous stem cell rescue. None have been shown to improve patient survival. On the other hand, the integration of concurrent thoracic radiation and prophylactic cranial irradiation has improved the survival outcomes in patients with limited disease. In extensive disease, irinotecan combined with cisplatin has shown promise in improving survival over conventional platinum/etoposide chemotherapy schedules and a confirmatory study is awaited. The future of SCLC treatment may however lie with molecularly targeted therapies, such as antiangiogenesis agents and signal transduction inhibitors, which are being studied at present.

Intensive chemotherapy with whole blood stem-cell support and concurrent chest radiotherapy in small cell lung cancer: a phase I/II trial

Intensive chemotherapy combined with chest radiation may ameliorate survival in small cell lung cancer (SCLC). In a prospective study, we treated 18 patients with limited SCLC with an intensive sequential single agent (ifosfamide, carboplatin, etoposide and paclitaxel, (ICE-T)) chemotherapy with the support of unprocessed stem-cell enriched whole blood and G-CSF and concomitant bi-fractionated chest radiotherapy (60 Gy). The treatment was delivered in a short time of 10 weeks. The results were compared with an historical patient group treated with six cycles of standard chemotherapy of etoposide and cisplatin and concomitant chest radiotherapy. After a 3-year median follow up, the 2-year progression free (PFS) and overall survival (OS) are 54 and 63% in the ICE-T group, respectively. In the control group, median PFS and OS were 13 and 17 months and the 2-year PFS and OS were 32% (P=0.20) and 47% (P=0.25), respectively. This short and intensive chemo-radiotherapy regimen is well tolerated and induces promising survival results. The use of stem cell enriched whole blood should be investigated in larger randomized studies.

Standard- and high-dose etoposide, ifosfamide, carboplatin, and epirubicin in 100 patients with small-cell lung cancer: a mature follow-up report

BACKGROUND

We conducted a phase I-II trial to assess the feasibility and activity of a combination chemotherapy regimen with etoposide, ifosfamide, cisplatin or carboplatin, and epirubicin in limited-disease (LD, stages I-IIIB) and extensive-stage (ED, stage IV) small-cell lung cancer (SCLC).

PATIENTS AND METHODS

Standard-dose chemotherapy (SDC) consisting of etoposide (500 mg/m2), ifosfamide (4000 mg/m2), cisplatin (50 mg/m2) and epirubicin (50 mg/m2) (VIP-E), followed by granulocyte colony-stimulating factor (G-CSF), was given to 100 patients with SCLC. Thirty patients with qualifying responses to VIP-E proceeded to high-dose chemotherapy (HDC) with autologous peripheral blood stem-cell transplantation (PBSCT) after etoposide (1,500 mg/m2), ifosfamide (12,000 mg/m2), carboplatin (750 mg/m2) and epirubicin (150 mg/m2) (VIC-E) conditioning. RESULTS OF STANDARD-DOSE VIP-E: Ninety-seven patients were evaluable for response. The objective response rate was 81% in LD SCLC (33% CR, 48% PR; excluding patients in surgical CR) and 77% in ED SCLC (18% CR, 58% PR). The treatment-related mortality (TRM) of SDC was 2%. Two additional patients in CR from their SCLC developed secondary non-small-cell lung cancers (NSCLC), and both were cured by surgery. The median survival was 19 months in LD SCLC and 6 months in ED SCLC. The five-year survivals were 36% in LD and 0% in ED SCLC. RESULTS OF HIGH-DOSE VIC-E: HDC was feasible in 16% of ED-, and 58% of LD-patients. All HDC patients (n = 30) improved or maintained prior responses. Four patients died of early treatment-related complications (TRM 13%). Two additional patients in CR from their SCLC developed secondary malignancies (esophageal cancer, secondary chronic myelogenous leukemia). The median survivals were 26 months in LD SCLC, and 8 months in ED SCLC. The five-year survival was 50% in LD and 0% in ED SCLC.

CONCLUSIONS

Despite high response rates, survival after VIP-E SDC and VIC-E HDC in patients with ED SCLC is not superior to that achieved with less toxic traditional regimens. The high five-year survival rates achieved with these protocols in LD SCLC probably reflect both patient selection (high proportion of patients with prior surgical resection) and the high activity of our chemotherapy regimen in combination with radiotherapy. A study comparing protocols using simultaneous radiation therapy and chemotherapy, and other dose-escalated forms of SDC with HDC is needed to further define the role of this treatment modality in SCLC. Given the high rate of secondary malignancies observed in patients in CR > 2 years in our study, close follow-up and early treatment of these neoplasms may contribute to maintaining overall survival in patients with SCLC.