Synergistic interaction between topotecan and microtubule-interfering agents

Final survival analysis of topotecan and paclitaxel for first-line treatment of advanced cervical cancer: An NRG oncology randomized study

OBJECTIVE

To determine whether a non‑platinum chemotherapy doublet improves overall survival (OS) among patients with recurrent/metastatic cervical carcinoma.

METHODS

Gynecologic Oncology Group protocol 240 is a phase 3, randomized, open-label, clinical trial that studied the efficacy of paclitaxel 175 mg/m2 plus topotecan 0.75 mg/m2 days 1-3 (n = 223) vs cisplatin 50 mg/m2 plus paclitaxel 135 or 175 mg/m2 (n = 229), in 452 patients with recurrent/metastatic cervical cancer. Each chemotherapy doublet was also studied with and without bevacizumab (15 mg/kg). Cycles were repeated every 21 days until progression, unacceptable toxicity, or complete response. The primary endpoints were OS and the frequency and severity of adverse effects. We report the final analysis of OS.

RESULTS

At the protocol-specified final analysis, median OS was 16.3 (cisplatin-paclitaxel backbone) and 13.8 months (topotecan-paclitaxel backbone) (HR 1.12; 95% CI, 0.91-1.38; p = 0.28). Median OS for cisplatin-paclitaxel and topotecan-paclitaxel was 15 vs 12 months, respectively (HR 1.10; 95% CI,0.82-1.48; p = 0.52), and for cisplatin-paclitaxel-bevacizumab and topotecan-paclitaxel-bevacizumab was 17.5 vs 16.2 months, respectively (HR 1.16; 95% CI, 0.86-1.56; p = 0.34). Among the 75% of patients in the study population previously exposed to platinum, median OS was 14.6 (cisplatin-paclitaxel backbone) vs 12.9 months (topotecan-paclitaxel backbone), respectively (HR 1.09; 95% CI, 0.86-1.38;p = 0.48). Post-progression survival was 7.9 (cisplatin-paclitaxel backbone) vs 8.1 months (topotecan-paclitaxel backbone) (HR 0.95; 95% CI, 0.75-1.19). Grade 4 hematologic toxicity was similar between chemotherapy backbones.

CONCLUSIONS

Topotecan plus paclitaxel does not confer a survival benefit to women with recurrent/metastatic cervical cancer, even among platinum-exposed patients. Topotecan-paclitaxel should not be routinely recommended in this population. NCT00803062.

Bifunctional G-Quadruplex Aptamer Targeting Nucleolin and Topoisomerase 1: Antiproliferative Activity and Synergistic Effect of Conjugated Drugs

As a counterpart to antibody-drug conjugates (ADCs), aptamer-drug conjugates (ApDCs) have been considered a promising strategy for targeted therapy due to the various benefits of aptamers. However, an aptamer merely serves as a targeting ligand in ApDCs, whereas the antibody enables the unexpected therapeutic efficacy of ADCs through antibody-dependent cellular cytotoxicity (ADCC). In this study, we developed a tumor-specific aptamer with an effector function and used it to confirm the feasibility of more potent ApDCs. First, we designed a nucleolin (NCL)-binding G-quadruplex (GQ) library based on the ability of NCL to bind to telomeric sequences. We then identified a bifunctional GQ aptamer (BGA) inhibiting the catalytic activity of topoisomerase 1 (TOP1) by forming an irreversible cleavage complex. Our BGA specifically targeted NCL-positive MCF-7 cells, exhibiting antiproliferative activity, and this suggested that tumor-specific therapeutic aptamers can be developed by using a biased library to screen aptamer candidates for functional targets. Finally, we utilized DM1, which has a synergistic interaction with TOP1 inhibitors, as a conjugated drug. BGA-DM1 exerted an anticancer effect 20-fold stronger than free DM1 and even 10-fold stronger than AS1411 (NCL aptamer)-DM1, highlighting our approach to develop synergistic ApDCs. Therefore, we anticipate that our library might be utilized for the identification of aptamers with effector functions. Furthermore, by employing such aptamers and appropriate drugs, synergistic ApDCs can be developed for targeted cancer therapy in a manner distinct from how ADCs exhibit additional therapeutic efficacy.

Pharmacological Treatment of Patients with Metastatic, Recurrent or Persistent Cervical Cancer Not Amenable by Surgery or Radiotherapy: State of Art and Perspectives of Clinical Research

Cervical cancer patients with distant or loco-regional recurrences not amenable by surgery or radiotherapy have limited treatment options, and their 5-year overall survival (OS) rates range from 5% to 16%. The purpose of this paper is to assess the results obtained with chemotherapy and biological agents in this clinical setting. Several phase II trials of different cisplatin (CDDP)-based doublets and a phase III randomized trial showing a trend in response rate, progression-free survival, and OS in favor of CDDP + paclitaxel (PTX) compared with other CDDP-based doublets have been reviewed. The factors predictive of response to chemotherapy as well as the benefits and risks of the addition of bevacizumab to CDDP + PTX have been analyzed. The FDA has recently approved pembrolizumab for patients with recurrent or metastatic cervical cancer in progression on or after chemotherapy whose tumors were PD-L1 positive. Interesting perspectives of clinical research are represented by the use of immune checkpoint inhibitors alone or in addition to chemotherapy, whereas PARP inhibitors and PI3K inhibitors are still at the basic research phase, but promising.

Cervical cancer - State of the science: From angiogenesis blockade to checkpoint inhibition

Vascular endothelial growth factor (VEGF) has emerged as a therapeutic target in several malignancies, including cervical cancer. Chemotherapy doublets combined with the fully humanized monoclonal antibody, bevacizumab, now constitute first-line therapy for women struggling with recurrent/metastatic cervical carcinoma. Regulatory approval for this indication was based on the phase III randomized trial, GOG 240, which demonstrated a statistically significant and clinically meaningful improvement in overall survival when bevacizumab was added to chemotherapy: 17.0 vs 13.3 months; HR 0.71; 98% CI, 0.54-0.95; p = .004. Incorporation of bevacizumab resulted in significant improvements in progression-free survival and response. These benefits were not accompanied by deterioration in quality of life. GOG 240 identified vaginal fistula as a new adverse event associated with bevacizumab use. All fistulas occurred in women who had received prior pelvic radiotherapy, and none resulted in emergency surgery, sepsis, or death. Final protocol-specified analysis demonstrated continued separation of the survival curves favoring VEGF inhibition: 16.8 vs 13.3 months; HR 0.77; 95% CI, 0.62-9.95; p = .007. Post-progression survival was not significantly different between the arms in GOG 240. Moving forward, immunotherapy has now entered the clinical trial arena to address the high unmet clinical need for effective and tolerable second line therapies in this patient population. Targeting the programmed cell death 1/programmed death ligand 1 (PD-1/PD-L1) pathway using checkpoint inhibitors to break immunologic tolerance is promising. The immunologic landscape involving human papillomavirus-positive head and neck carcinoma and cutaneous squamous cell carcinoma can be informative when considering feasibility of checkpoint blockade in advanced cervical cancer. Phase II studies using anti-PD-1 molecules, nivolumab and pembrolizumab are ongoing, and GOG 3016, the first phase III randomized trial of a checkpoint inhibitor (cemiplimab) in cervical cancer, recently activated. Important considerations in attempts to inhibit the inhibitors include pseudoprogression and post-progression survival, abscopal effects, and immune-related adverse events, including endocrinopathies.

Combination therapy with topotecan, paclitaxel, and bevacizumab improves progression-free survival in recurrent small cell neuroendocrine carcinoma of the cervix

OBJECTIVES

To assess if the combination of topotecan, paclitaxel, and bevacizumab (TPB) was active in recurrent SCCC and to compare the survival of patients with SCCC who received TPB to a group of women with SCCC who did not receive this regimen.

METHODS

We retrospectively analyzed women with recurrent SCCC who received chemotherapy as primary therapy. Women treated with TPB for first recurrence were compared to women treated with non-TPB chemotherapy.

RESULTS

Thirteen patients received TPB, and 21 received non-TPB chemotherapy, most commonly platinum with or without a taxane. Median progression-free survival (PFS) was 7.8months for TPB and 4.0months for non-TPB regimens (hazard ratio [HR] 0.21, 95% CI 0.09-0.54, P=0.001). Median overall survival (OS) was 9.7months for TPB and 9.4months for non-TPB regimens (HR 0.53, 95% CI 0.23-1.22, P=0.13). Eight women (62%) who received TPB versus four (19%) who received non-TPB regimens were on treatment for >6months (P=0.02), and four patients (31%) in the TPB group versus two (10%) in the non-TPB group were on treatment for >12months (P=0.17). In the TPB group, three patients (23%) had complete response, two (15%) had complete response outside the brain with progression in the brain, 3 (23%) had a partial response, 2 (15%) had stable disease, and 3 (23%) had progressive disease.

CONCLUSIONS

These findings indicate that TPB for recurrent SCCC significantly improved PFS over non-TPB regimens, and trends towards improved OS. Furthermore, a significant number of patients had a durable clinical benefit.

Phase I Clinical Study of Irinotecan Plus S-1 in Patients With Advanced or Recurrent Cervical Cancer Previously Treated With Platinum-Based Chemotherapy

OBJECTIVES

This study aimed to determine the maximum tolerated dose and acute dose-limiting toxicities (DLTs) of intravenous irinotecan plus oral S-1 in patients with advanced or recurrent uterine cervical cancer.

METHODS

Irinotecan was administered intravenously over the course of 90 minutes on day 1, and S-1 was given orally in 2 divided doses from days 1 to 14 of a 21-day cycle. The dose of S-1 was escalated in a stepwise fashion from 40 (level 1) to 60 mg/m (level 2) and then 80 mg/m (level 3), whereas the dosage of irinotecan remained the same (150 mg/m). The primary end point for the escalation study was acute DLT that occurred within 2 cycles of chemotherapy.

RESULTS

Twelve patients were enrolled and treated over 3 dose levels. Their median age was 47 years (range, 28-48 years). At level 1, one episode of grade 3 anemia and a grade 3 fatigue were observed, but no DLT developed. At level 2, the first patient experienced febrile neutropenia, which was considered to be a DLT. To evaluate the toxicity of this dose level, 5 more patients were evaluated. However, no DLT developed in these patients. At level 3, although grade 1 to 2 hematological and nonhematological toxicities developed, no DLT occurred.

CONCLUSIONS

In women with advanced or recurrent cervical cancer previously treated with platinum-based chemotherapy, S-1 plus irinotecan in a triweekly setting is a reasonable treatment regimen with an acceptable toxicity profile. The recommended doses of S-1 and irinotecan for this regimen are 80 and 150 mg/m, respectively.

Pharmacologic management of advanced cervical cancer: antiangiogenesis therapy and immunotherapeutic considerations

As a consequence of disparities in access to and utilization of preventative healthcare, the incidence and death rates from cervical cancer remain substantial in the face of indisputable evidence that screening saves lives. While disparities persist, there will be an urgent need for research into the treatment of advanced forms of this disease. In this review, we explore the evolution of the treatment of metastatic, recurrent, and persistent cervical cancer from cytotoxic agents to targeted therapy. We discuss why targeted therapies are unlikely to produce sustained responses alone but may be more successful in combination with immunotherapies. We also provide a rationale for the potential next phase in treatment of this challenging disease-combined therapy with antiangiogenic agents and immune checkpoint inhibitors. In doing so, we highlight recent paradigm shifts within cancer therapeutics, including the shift in focus from the tumor cell itself to the tumor microenvironment, and from stimulating the immune system to inhibiting the inhibitors of an adequate immune response.

Poly(d,l-lactide-co-glycolide)-chitosan composite particles for the treatment of lung cancer

Tumor heterogeneity makes combination chemotherapy one of the preferred modes of treatment regimens. In this work, sequential exposure of two anticancer agents, paclitaxel (Tx) followed by topotecan (TPT), was shown to have a synergistic effect on non-small cell lung cancer (NSCLC) cell line, NCI-H460. In order to improve patient compliance, the aforementioned concept was translated into a drug delivery system comprising of poly(d,l-lactide-co-glycolide) (PLGA)-chitosan composite particles. TPT-containing chitosan micro-/nanoparticles were prepared by the facile technique of electrospraying and encapsulated within PLGA microparticles using emulsion-solvent evaporation technique for delayed release of TPT. The formulation containing Tx- and TPT-loaded composite particles demonstrated synergism when exposed to NCI-H460 cellular aggregates (tumoroids) generated in vitro. Overall, the results of this study demonstrated the potential of the formulation containing Tx and PLGA-chitosan (TPT-loaded) composite particles for the treatment of lung cancer.

Chemotherapy in the treatment of metastatic, persistent, and recurrent cervical cancer

PURPOSE OF REVIEW

Patients with cervical cancer represent a vulnerable population with limited chemotherapeutic options. This year, two large trials focusing on detection/screening and treatment of advanced stage cervical cancer were featured in the opening plenary session of the American Society of Clinical Oncology Annual Meeting. As such, a review of the evolution of chemotherapy in the treatment of this disease is warranted.

RECENT FINDINGS

Following the establishment of cisplatin as an effective single-agent regimen in patients with advanced stage, recurrent, or persistent cervical cancer, several platinum-containing combinations were studied. Ultimately, the adoption of cisplatin chemosensitizing radiation resulted in relative 'cisplatin resistance' and the concept of nonplatinum doublets emerged as an active area of investigation.

SUMMARY

In an era of biologics, combined therapy with cytotoxic drugs and molecular targeted agents, as well as the use of nonplatinum doublets, represent an exciting area yet to be fully explored.

Design, synthesis, and biological evaluations of tumor-targeting dual-warhead conjugates for a taxoid-camptothecin combination chemotherapy

Novel tumor-targeting dual-warhead conjugates, 2 (DW-1) and 3 (DW-2), which consist of a next-generation taxoid, 1 (SB-T-1214), and camptothecin as two warheads, self-immolative disulfide linkers for drug release, biotin as the tumor-targeting moiety, and 1,3,5-triazine as the tripod splitter module, were designed and synthesized. The potency of 2 was evaluated against MX-1, MCF-7, ID8, L1210FR (BR+, biotin receptor overexpressed) and WI38 (BR-, normal) cell lines in the absence and presence of glutathione (GSH), which is an endogenous thiol that triggers drug release inside the cancer cells. With the GSH and resuspension protocol, 2 exhibited IC50 values of 3.22-9.80 nM against all BR+ cancer cell lines, and 705 nM against WI38. Thus, there was a two orders of magnitude higher selectivity to cancer cells. Also, a clear cooperative effect was observed for the taxoid-camptothecin combination when two drugs were delivered to the cancer cells specifically in the form of a dual-warhead conjugate.

Improved survival with bevacizumab in advanced cervical cancer

BACKGROUND

Vascular endothelial growth factor (VEGF) promotes angiogenesis, a mediator of disease progression in cervical cancer. Bevacizumab, a humanized anti-VEGF monoclonal antibody, has single-agent activity in previously treated, recurrent disease. Most patients in whom recurrent cervical cancer develops have previously received cisplatin with radiation therapy, which reduces the effectiveness of cisplatin at the time of recurrence. We evaluated the effectiveness of bevacizumab and nonplatinum combination chemotherapy in patients with recurrent, persistent, or metastatic cervical cancer.

METHODS

Using a 2-by-2 factorial design, we randomly assigned 452 patients to chemotherapy with or without bevacizumab at a dose of 15 mg per kilogram of body weight. Chemotherapy consisted of cisplatin at a dose of 50 mg per square meter of body-surface area, plus paclitaxel at a dose of 135 or 175 mg per square meter or topotecan at a dose of 0.75 mg per square meter on days 1 to 3, plus paclitaxel at a dose of 175 mg per square meter on day 1. Cycles were repeated every 21 days until disease progression, the development of unacceptable toxic effects, or a complete response was documented. The primary end point was overall survival; a reduction of 30% in the hazard ratio for death was considered clinically important.

RESULTS

Groups were well balanced with respect to age, histologic findings, performance status, previous use or nonuse of a radiosensitizing platinum agent, and disease status. Topotecan-paclitaxel was not superior to cisplatin-paclitaxel (hazard ratio for death, 1.20). With the data for the two chemotherapy regimens combined, the addition of bevacizumab to chemotherapy was associated with increased overall survival (17.0 months vs. 13.3 months; hazard ratio for death, 0.71; 98% confidence interval, 0.54 to 0.95; P=0.004 in a one-sided test) and higher response rates (48% vs. 36%, P=0.008). Bevacizumab, as compared with chemotherapy alone, was associated with an increased incidence of hypertension of grade 2 or higher (25% vs. 2%), thromboembolic events of grade 3 or higher (8% vs. 1%), and gastrointestinal fistulas of grade 3 or higher (3% vs. 0%).

CONCLUSIONS

The addition of bevacizumab to combination chemotherapy in patients with recurrent, persistent, or metastatic cervical cancer was associated with an improvement of 3.7 months in median overall survival. (Funded by the National Cancer Institute; GOG 240 ClinicalTrials.gov number, NCT00803062.).

Combination of single walled carbon nanotubes/graphene oxide with paclitaxel: a reactive oxygen species mediated synergism for treatment of lung cancer

Heterogeneity in tumors has led to the development of combination therapies that enable enhanced cell death. Previously explored combination therapies mostly involved the use of bioactive molecules. In this work, we explored a non-conventional strategy of using carbon nanostructures (CNs) [single walled carbon nanotube (SWNT) and graphene oxide (GO)] for potentiating the efficacy of a bioactive molecule [paclitaxel (Tx)] for the treatment of lung cancer. The results demonstrated enhanced cell death following combination treatment of SWNT/GO and Tx indicating a synergistic effect. In addition, synergism was abrogated in the presence of an anti-oxidant, N-acetyl cysteine (NAC), and was therefore shown to be reactive oxygen species (ROS) dependent. It was further demonstrated using bromodeoxyuridine (BrdU) incorporation assay that treatment with CNs was associated with enhanced mitogen associated protein kinase (MAPK) activation that was ROS mediated. Hence, these results for the first time demonstrated the potential of SWNT/GO as co-therapeutic agents with Tx for the treatment of lung cancer.

Prediction of progression-free survival and response to paclitaxel plus carboplatin in patients with recurrent or advanced cervical cancer

OBJECTIVE

The aim of this study was to identify predictors of the response to paclitaxel-carboplatin chemotherapy (TC) in recurrent or patients with advanced cervical cancer.

METHODS

The records of 61 consecutive women with recurrent or advanced cervical cancer who were treated with TC were retrospectively reviewed. Data regarding their primary disease, follow-up, recurrence, and the activity and toxicity of TC were collected. Multivariate analysis was performed using the Cox proportional hazards regression model to identify predictors of the response to TC. Survival was calculated using the Kaplan-Meier method and compared using the log-rank test.

RESULTS

Overall, TC was well tolerated and displayed a response rate of 60.7% (19 complete response and 18 partial response). The median progression-free survival was 14 months for all patients and 20 months for the responders. Grade 3 to grade 4 toxicities were observed in 51 patients (83.6%). Multivariate analysis revealed that performance status, symptom status, and prior chemotherapy were independent prognostic predictors of a poor response. Patient survival was inversely correlated with the number of these prognostic factors. When the patients were divided into 2 prognostic groups (low risk: patients with no or one poor prognostic factor; and high-risk: patients with 2 or more poor prognostic factors), the patients in the high-risk group had a significantly shorter progression-free survival than those in the low-risk group (4 vs 16 months, log-rank; P < 0.0001).

CONCLUSIONS

The combination of paclitaxel and carboplatin is effective in patients with recurrent or advanced cervical cancer. Our prognostic model composed of 3 clinical variables might enable physicians to identify patients who would not derive clinical benefit from TC and offer them the opportunity to receive other types of treatment.

Clinical relevance of human cancer xenografts as a tool for preclinical assessment: example of in-vivo evaluation of topotecan-based chemotherapy in a panel of human small-cell lung cancer xenografts

Prediction of human tumor response based on preclinical data could reduce the failure rates of subsequent new anticancer drugs clinical development. Human small-cell lung carcinomas (SCLC) are characterized by high initial sensitivity to chemotherapy but a low median survival time because of drug resistance. The aim of this study was to evaluate the therapeutic relevance of a panel of human SCLC xenografts established in our laboratory using one compromising drug in SCLC, topotecan (TPT). Six SCLC xenografts derived from six patients were used: three were sensitive to a combination of etoposide (VP16), cisplatin (CDDP), and ifosfamide (IFO), and three were resistant, as published earlier. Growth inhibition was greater than 84% for five xenografts at doses of 1-2 mg/kg/day. TPT was combined with IFO, etoposide (VP16), and CDDP. IFO improved the efficacy of TPT in three of the five xenografts and complete responses were obtained even with the less TPT-sensitive xenograft. VP16 increased the efficacy of two of four xenografts and complete responses were obtained. The combination of TPT and CDDP did not improve TPT responses for any of the xenografts tested. Semiquantitative reverse transcriptase-PCR of genes involved in drug response, such as topoisomerase I, topoisomerase IIalpha, multidrug resistance 1 (MDR1), multidrug resistance-associated protein (MRP), lung resistance-related protein (LRP), and glutathione S-transferase pi (GSTpi), did not explain the variability in drug sensitivity between SCLC xenografts. In conclusion, these preclinical data mirror those from published clinical studies suggesting that our panel of SCLC xenografts represents a useful tool for preclinical assessment of new treatments.

Recent achievements and future developments in advanced and recurrent cervical cancer: trials of the Gynecologic Oncology Group

Following publication of five pivotal randomized trials of concurrent chemo-irradiation for patients with locally advanced cervical cancer (ie, International Federation of Gynecology and Oncology (FIGO] stages IB2-IVA) in 1999 and 2000, the National Cancer Institute issued a Clinical Alert advising that concurrent chemotherapy (typically, single-agent cisplatin) be incorporated into the treatment program of women scheduled to receive definitive pelvic radiotherapy. Although the adoption of this new standard has improved overall survival and decreased the recurrence rate by 50%, for those patients who do relapse, the prognosis is very poor and, ultimately, therapy in this setting is palliative in nature. The Gynecologic Oncology Group (GOG) has now completed eight randomized trials for metastatic and recurrent cervical cancer, all of which have studied cisplatin-based regimens. The eighth trial (protocol 204) compared four cisplatin-based doublets containing paclitaxel, topotecan, vinorelbine, or gemcitabine. Because the vast majority of patients are now expected to receive cisplatin "up front" as part of primary therapy with pelvic radiation, there are concerns for the development of drug-resistant clones in recurrences both inside and outside of the radiation field. The GOG has recently reported the results from a phase II trial evaluating the anti-vascular agent, bevacizumab, in women who were eligible for second-line or third-line therapy for metastatic and/or recurrent disease (protocol 227C). It becomes imperative that we continue to evaluate novel regimens for this disease.

Phase I dose escalation study of vinorelbine and topotecan combination chemotherapy in patients with recurrent lung cancer

Background

A platinum doublet is the current standard treatment for good performance status patients with advanced non-small cell lung cancer (NSCLC) and extensive stage small cell lung cancer (SCLC) with good performance status. However, platinum-based treatment may be associated with significant toxicities, therefore alternative platinum-free combinations should be investigated. Topotecan is a topoisomerase I inhibitor that exerts its cytotoxic effect through stabilization of the topoisomerase I-DNA complex. Preclinical data suggests synergy between topoisomerase I inhibitors and mitotic spindle poisons. Considerable hematologic toxicities have been reported with topotecan dosed for 5 consecutive days in combination with vinorelbine. Therefore, the aim of this study was to evaluate the optimal dosage and the maximal tolerated dose (MTD) of topotecan and vinorelbine in patients with relapsed or refractory non-small cell or small cell lung cancer administered on an alternate dosing schedule.

Methods

From February, 2004 to March, 2007 eighteen patients with advanced or recurrent NSCLC or SCLC previously treated with chemotherapy were enrolled. Patients were heavily pretreated with 22% having received at least 3 prior lines of chemotherapy. Vinorelbine was administered at a fixed dose (20 mg/m²) and topotecan at escalating doses (2, 2.5, 3, 3.5, and 4 mg/m²) on days 1 and 8 every 21 days.

Results

The MTD was not reached in any of the 5 cohorts, with only one dose limiting toxicity (DLT) occurring in cohort 4. Non-hematological toxicities were manageable. One patient had a partial response with four patients (27%) achieving stable disease. The median progression-free and overall survival for all patients, were 2.7 months (95% CI: 1.6, 9.1) and 10.5 months (95% CI: 4.2, 22.7), respectively.

Conclusion

Vinorelbine and topotecan administered on days 1 and 8 every 21 days is well tolerated without any DLT seen with previously investigated topotecan schedules. This doublet provides a potentially active non-platinum containing doublet for the treatment of patients with advanced SCLC and NSCLC. Vinorelbine and topotecan should therefore be investigated in subsequent phase II studies at a dose of 20 mg/m² and 4 mg/m², respectively.

Trial Registration Number

NCT00287963.

Addition of topotecan to standard cisplatin/etoposide combination in patients with extended stage small cell lung carcinoma

BACKGROUND

Topotecan is an active agent for the management of untreated and recurrent extensive-disease small cell lung cancer (ED-SCLC). This study was designed to evaluate the efficacy and safety of a triplet combination with topotecan added to the standard PE regimen in previously untreated patients with ED-SCLC.

MATERIALS AND METHODS

Twenty-one patients (median age 55 years, and 18 male) with chemotherapy-naive ED-SCLC were enrolled into the study. PET treatment consisted of etoposide 80mg/m(2), cisplatin 20mg/m(2) and topotecan 0.75mg/m(2) and all were given intravenously on days 1 to 3 for every 3 weeks.

RESULTS

Leucopoenia and/or neutropenia and to a lesser extent thrombocytopenia were the main dose-limiting toxicities. Severe leucopenia/neutropenia were observed in 14 (67%)/12 (57%) patients, and only two (10%) developed febrile neutropenia. Severe thrombocytopenia was observed in 6 (29%) patients and one patient died due to orbital and cerebral haemorrhage. Dose reductions were required in 13 (62%) patients, delays in 8 (38%) patients and early treatment discontinuation in 3 (14%) patients. The overall response rate was 52.6% (95% CI: 28, 9-75.6) with 2 (10.5%) complete and 8 (42.1%) partial responses. The overall median survival time was 6.6 months (range 0.5-16.5 months) and the 6-month overall survival was 65.3%+/-11.7. The overall median survival time of responders was 9.7 months compared to 5.7 months in non-responders (p=0.026).

CONCLUSION

Topotecan combined with PE regimen with this schedule and dosage does not seem to provide any benefit in terms of response and survival in ED-SCLC patients and does not deserve further studies.

Treatment options in the management of ovarian cancer

The standard regimen used as primary chemotherapy of ovarian cancer is combination chemotherapy using paclitaxel and carboplatin. The main objective of first-line chemotherapy is to induce complete response. Although most cases respond to the initial chemotherapy, many cases relapse within 3 years. Such relapsed and persistent cases become resistant to first-line chemotherapy and require second-line chemotherapy. Objectives of such a second-line chemotherapy are to obtain disease palliation to cease disease progression. Meanwhile, consolidation or maintenance chemotherapy may be added to prevent or inhibit disease relapse for patients with advanced disease after induction of complete remission by a primary chemotherapy. When the unresectable tumour is presumed by primary surgery, neoadjuvant chemotherapy may be selected. Recently, conventional cytotoxic anticancer drugs containing paclitaxel have been shown to be capable of inhibiting angiogenesis. The notion of 'redefining' chemotherapeutic drugs has been recognised; thus, continuous low-dose chemotherapy -- so-called metronomic chemotherapy -- has been approved as a new concept. Many new molecular-targeted therapies became available for clinical cancer therapy. The explosion of new molecular targets and the development and application of many powerful technologies should accelerate the discovery of innovative molecular therapeutics. Understanding the molecular mechanisms will help to clarify the pathways in ovarian cancer development and help to identify new therapeutic and diagnostic targets. These are exciting times for new drug development and the treatment of cancer. Cautious optimism should prevail for all investigators involved in translating these exciting new biological findings into new pharmacological agents for treatment of cancer.

Preclinical Evaluation of Gemcitabine Combination Regimens for Application in Acute Myeloid Leukemia

The DNA antimetabolite gemcitabine is an anticancer agent with shown preclinical and clinical utility and a low toxicity profile. In this study, we sought to identify and optimize drug partners for binary and tertiary combinations with gemcitabine for use in the treatment of acute myelogenous leukemia (AML). Drug interaction was assessed by growth inhibition assay with metabolic end points. The combination index method was used to evaluate combinations of gemcitabine with fludarabine, paclitaxel, chlorambucil, doxorubicin, mitoxantrone, and SN-38 in U937 human AML cells. A three-dimensional method was used to determine the effect of dose ratio and schedule on drug interaction. Mechanisms underlying interactions related to cell cycle effects and apoptosis were assessed by flow cytometric and caspase-3 and -7 assays, respectively. The most synergistic binary combination was gemcitabine + fludarabine. The most synergistic tertiary combination was gemcitabine + fludarabine + paclitaxel, where the interaction was sequence dependent with paclitaxel given before gemcitabine + fludarabine, producing a 2-fold increase in synergy. Cell cycle analysis did not reveal a significant G(2)-M arrest, suggesting that the synergistic effect of paclitaxel in this combination, which produced the greatest caspase activation, might be independent of microtubule stabilization. In contrast, the gemcitabine + fludarabine + mitoxantrone combination was synergistic and schedule independent. Moreover, few ratios of gemcitabine + fludarabine to mitoxantrone were antagonistic, which could be important for clinical translation. In conclusion, synergistic interactions with gemcitabine occurred with several drugs, the most promising being gemcitabine + fludarabine, gemcitabine + fludarabine + paclitaxel, and gemcitabine + fludarabine + mitoxantrone. These findings provided a rationale for clinical trials of gemcitabine + fludarabine and gemcitabine + mitoxantrone where responses were observed in heavily pretreated AML patients.

Ex vivo characterization of XR11576 (MLN576) against ovarian cancer and other solid tumors

XR11576 (MLN576) is a novel monophenazine with a mechanism of action that includes interaction with both topoisomerase (Topo) I and II. The aim of this study was to evaluate its cytotoxicity against fresh tumor cells taken from patients with a variety of solid tumors. Cells were obtained from 89 patients and exposed for 6 days to XR11576 alone, or in combination with doxorubicin, cisplatin, treosulfan, paclitaxel or vinorelbine. Cell survival was measured using the ATP-Tumor Chemosensitivity Assay (ATP-TCA). Immunohistochemical staining of Topo I, Topo IIalpha and MDR1 was performed on paraffin-embedded blocks in those tumors for which tissue was available (n = 49). Overall, the median IC90 and IC50 values of XR11576 in tumor-derived cells were 242 and 110 nM, respectively. In all samples XR11576 was more potent than the other cytotoxics tested. Breast and gynecological malignancies were most sensitive to XR11576, while the potency of this compound was slightly attenuated in gastrointestinal tumors, in which the median IC90 and IC50 values were 308 and 212 nM, respectively. Cases of synergism were identified when combining XR11576 with vinorelbine (nine of 30 samples) and doxorubicin (12 of 38 samples), while the addition of paclitaxel resulted in an antagonistic effect (CI50>1.2) in 38 of 42 tumors. A very modest correlation by linear regression analysis was found between the intensity of MDR1 staining and the IC50 of XR11576 (r = 0.311, p = 0.0312), but not with the IC90 (r = 0.247, NS). These data support the rapid introduction of XR11576 to clinical trials and suggest that it may be effective against a broad spectrum of tumor types.

Topotecan in the treatment of recurrent small cell lung cancer: an update

Small cell lung cancer (SCLC) is an aggressive malignancy with a high propensity for early regional and distant metastasis. Response rates to first-line chemotherapy are typically high, but short lived. The outlook for patients with recurrent SCLC is poor. A variety of single- and multi-agent chemotherapy regimens have met with limited success in patients with recurrent SCLC, and survival is generally measured in weeks. Until recently, further chemotherapy was not widely considered appropriate for patients with relapsed SCLC. The choice of chemotherapy at relapse is dependent on many factors, including type of and response to first-line therapy, the treatment-free interval, and the patient's performance status. Intravenous topotecan (Hycamtin; GlaxoSmithKline; Philadelphia, PA) has provided oncologists and patients in many countries with an effective and tolerable therapeutic option for recurrent SCLC. The clinical profile of topotecan was established in several phase II studies and confirmed in a randomized, phase III trial versus cyclophosphamide, doxorubicin (Adriamycin; Bedford Laboratories; Bedford, OH), and vincristine (Oncovin; Eli Lilly and Company; Indianapolis, IN)--CAV. In those studies, topotecan exhibited antitumor activity in both chemosensitive and refractory disease. Further, topotecan therapy is associated with significant symptom palliation in this patient population. Because the toxicity profile of topotecan is predictable, generally manageable, and noncumulative, the agent also has potential utility in patients with a poor prognosis and/or a poor performance status. Alternative dosing regimens (lower dose, weekly) and the introduction of an oral formulation may expand the use of topotecan as a single agent and in combination therapy in the second- and first-line treatment of this disease.

Topotecan in the first-line treatment of small cell lung cancer

Small cell lung cancer (SCLC) is generally sensitive to first-line chemotherapy, but limited disease often recurs and extensive disease is rarely curable. The most common first-line therapy regimen is cisplatin (Platinol; Bristol-Myers Squibb; Princeton, NJ) plus etoposide (Etopophos; Bristol-Myers Squibb)--PE, which is associated with overall response rates >80% in patients with limited SCLC. Although it is associated with median survival times of approximately 18-20 months for limited disease, PE yields median survival times of only approximately 8-12 months in patients with extensive disease, and symptom palliation becomes the primary therapeutic goal. The toxicities of PE may undermine quality of life and leave patients more susceptible to adverse events during subsequent therapies. Topotecan (HYCAMTIN; GlaxoSmithKline; Philadelphia, PA), an established treatment for recurrent SCLC, is being investigated in the first-line setting because of its novel mechanism of action; predictable, noncumulative, and manageable toxicities; and potential synergy with other active agents. Several recent phase II trials have generated promising results for topotecan-based combination regimens, including topotecan/paclitaxel (TAXOL; Bristol-Myers Squibb) (overall response rates 45%-100%), topotecan/etoposide (overall response, 95%), and topotecan, paclitaxel, and platinum agent triplets (overall response rates 51%-93%). The most frequent serious toxicity associated with these regimens was reversible and noncumulative neutropenia, which was generally manageable with supportive care. Additional clinical trials to investigate topotecan-based combination regimens and confirm their role in the first-line treatment of SCLC are under way.

A Phase II trial of paclitaxel and topotecan with filgrastim in patients with recurrent or refractory glioblastoma multiforme or anaplastic astrocytoma

PURPOSE

Therapy for high-grade gliomas remains unsatisfactory. Paclitaxel and topotecan have separately demonstrated activity against gliomas. We conducted a Phase II trial of these agents in combination with filgrastim (G-CSF) in patients with recurrent or refractory glioblastoma multiforme or anaplastic astrocytoma.

PATIENTS AND METHODS

Adult patients with radiographic evidence of recurrent or progressive tumor following primary therapy were eligible for study. Patients received paclitaxel 175 mg/m2 IV over 3 h on day 1 and topotecan 1.0 mg/m2 IV over 30 min on days 1-5. Filgrastim 5 microg/kg was given days 6-14 for neutrophil support. Treatment cycles were repeated every 21 days.

RESULTS

Twenty patients were enrolled on study, and seventeen were considered evaluable for response. Two patients (12/%) exhibited partial remission and seven patients (41/%) exhibited stable disease in response to therapy. Hematologic toxicity was common with 25 /% of patients experiencing grade III or IV leukopenia despite G-CSF support. Two patients died of infectious complications on protocol, prompting suspension of further accrual.

CONCLUSION

Paclitaxel and topotecan with G-CSF support exhibits modest activity in adults with recurrent or refractory glioblastoma and anaplastic astrocytoma. The significant hematotoxicity encountered, however, cannot justify further investigation of this combination in patients with high grade brain tumors.

Review of the use of topotecan in ovarian carcinoma

Ovarian cancer is the fifth leading cause of cancer deaths in women. The majority of patients present with advanced disease and relapse after first-line platinum-based chemotherapy; therefore, many proceed to treatment with salvage chemotherapy. Currently available treatment options are generally no longer curative in the relapse setting; hence, the emphasis of treatment is towards disease control and palliation of symptoms. There are several agents available for the treatment of relapsed ovarian carcinoma, of which topotecan is one of the most widely studied and characterised. This review aims to evaluate the role of topotecan in the management of this disease by considering the properties of the compound, the clinical efficacy in Phase II and III studies, its role in first- and second-line treatment and alternative dosing strategies to overcome toxicity.

Synergistic antitumor activity of troxacitabine and camptothecin in selected human cancer cell lines

Troxacitabine (L-OddC) is an L-configuration deoxycytidine analog currently in phase II trials for the treatment of cancer. The cytotoxicity of L-OddC in combination with other anticancer agents has not been studied systematically. In the present study, we assessed the cytotoxic effects produced by the combinations of L-OddC and several commonly used chemotherapy drugs in a panel of cultured human cancer cell lines. Growth inhibition resulting from simultaneous exposure to two-drug combinations was determined using the methylene blue staining method. Camptothecin (CPT) and analogs exhibited additives to synergistic interactions with L-OddC by isobologram analysis. These effects were cell type-specific, with the most pronounced synergism being observed in KB oropharyngeal carcinoma and CPT-resistant KB100 cell lines. In KB cells, the total cellular uptake and DNA incorporation of L-OddC were increased by the addition of CPT. One explanation that emerged from enzyme assays of deoxycytidine kinase (dCK) and deoxycytidine monophosphate kinase (dCMPK), key enzymes involved in L-OddC phosphorylation, was that CPT protected against L-OddC-induced reduction in dCK and dCMPK activity. The resulting increase in l-OddC metabolites and incorporation into DNA was associated with enhanced L-OddC cytotoxicity. These findings will be useful in designing future clinical trials of combination chemotherapy with l-OddC and CPT analogs with the potential for a broad use against both hematological and solid tumors.

Phase II study of topotecan and paclitaxel for recurrent, persistent, or metastatic cervical carcinoma

OBJECTIVE

This trial investigated the safety and efficacy of paclitaxel and topotecan combination chemotherapy for patients with advanced cervical cancer (ACC).

METHODS

Patients with recurrent, persistent, or metastatic ACC and an ECOG performance status < or =2 were treated with 175 mg/m(2) paclitaxel on Day 1 and 1 mg/m(2) topotecan on Days 1-5 of a 21-day cycle with G-CSF support and the standard pretreatment regimen for paclitaxel. Patients were treated until disease progression or unacceptable toxicity.

RESULTS

Fifteen patients were enrolled, and 86 cycles of therapy (median, 5; range, 1-14) were administered. Grade 3/4 toxicities included anemia (47%), leukopenia (27%), neurotoxicity (13%), thrombocytopenia (13%), and diarrhea (13%). Among 13 evaluable patients, 7 (54%) responded (1 complete and 6 partial; 95% confidence interval = 29.2%, 76.8%). Three (23%) patients experienced stable disease. Progression-free and overall survival were 3.77 and 8.62 months, respectively.

CONCLUSION

The combination of paclitaxel/topotecan was generally well tolerated and active in the relapsed, recurrent, or metastatic ACC setting, with response rates comparable with those of other current ACC systemic therapies.

A phase I study of sequential administration of escalating doses of intravenous paclitaxel, oral topotecan, and fixed-dose oral etoposide in patients with solid tumors

BACKGROUND

Based on preclinical findings and on the clinical antitumor efficacy of sequential paclitaxel/topotecan and topotecan/etoposide, the authors sought to define the maximum tolerated doses (MTDs) and dose-limiting toxicities (DLTs) associated with a sequential combination of paclitaxel, topotecan, and etoposide in patients with solid tumors.

METHODS

The MTDs were determined through standard dose escalation in cohorts of three patients. Patients with refractory solid tumors and performance status < or = 2 were treated with intravenous paclitaxel 50-110 mg/m(2) (Day 1), oral topotecan 0.5-2.0 mg/m(2) (Days 2-4), and oral etoposide 160 mg/m(2) (Days 5-7) during every 21-day cycle. For dose-limiting neutropenia, granulocyte-colony-stimulating factor (G-CSF) was administered on Day 8 in subsequent cohorts. Blood samples were obtained before treatment during Cycle 1 (Days 1, 2, and 5) for topoisomerase I assessment.

RESULTS

Twenty-eight patients received a combined total of 129 cycles. The MTDs were paclitaxel 80 mg/m(2), topotecan 1.5 mg/m(2), and etoposide 160 mg/m(2) without G-CSF. In minimally pretreated patients, G-CSF allowed paclitaxel dose escalation to 110 mg/m(2). Three patients (11%) had radiologic partial responses, and 4 patients (14%) had stable disease. Day 2 topoisomerase I levels increased by 2-15 times relative to baseline levels in 7 of 14 patients analyzed (50%).

CONCLUSIONS

The novel sequential combination that was evaluated generally was well tolerated and active in patients with refractory solid tumors. Based on hematologic DLTs, the authors recommend further evaluation of paclitaxel 110 mg/m(2), topotecan 1.5 mg/m(2), and etoposide 160 mg/m(2) with G-CSF support in minimally pretreated patients.

First-line treatment regimens and the role of consolidation therapy in advanced ovarian cancer

Current first-line management for advanced ovarian cancer consists of cytoreductive surgery followed by chemotherapy, usually with a platinum/taxane combination. Although this approach has been shown to achieve overall response rates of 70-80% in clinical trials, the majority of patients relapse. A number of different approaches have been investigated to improve the efficacy of therapy, including the introduction of newer agents, such as topotecan, into chemotherapy regimens and the use of consolidation therapy. Encouraging results have been obtained in clinical trials of topotecan administered using a variety of different approaches, including replacement regimens, triplet regimens, and sequential doublet regimens. Other treatment modalities have included the use of drug resistance modifiers and intraperitoneal delivery of treatment. A variety of approaches to consolidation therapy have also been investigated, including radiotherapy, cytotoxic therapy, and intraperitoneal therapy. The use of topotecan has also shown promise in this setting, although further data from large, controlled trials are required. In summary, while good response rates are obtained using current first-line treatments, the high relapse rate indicates the need to develop more effective and durable treatment regimens including new agents with, perhaps, an increased emphasis on maintaining remission through the use of consolidation therapy.

Phase I study of paclitaxel and topotecan for the first-line treatment of extensive-stage small cell lung cancer

Extensive-stage small cell lung cancer (SCLC) is an aggressive disease with a median survival of approximately 8 months. Although current combination chemotherapy regimens provide high initial tumor response rates, they have not translated into large gains in survival. Topotecan and paclitaxel have nonoverlapping mechanisms of action and are active agents in SCLC. Additionally, these two agents demonstrate in vitro synergy in animal and human tumor models. We investigated the maximum tolerated dose of 3-day topotecan in combination with paclitaxel in previously untreated patients with extensive SCLC. Seventeen patients were enrolled in an open-label, phase I, dose-escalation study and were treated with intravenous paclitaxel 135-175 mg/m(2) over 1 hour on day 1, followed by intravenous topotecan 1.25-1.5 mg/m(2) over 30 minutes on days 1-3 of a 21-day course. Sixty-nine courses of therapy were administered with no delays due to hematologic toxicity. Prophylactic hematologic support was required for 24% of patients. The topotecan/paclitaxel combination was well tolerated, with 24%, 12%, and 6% of patients experiencing grade 3/4 neutropenia, anemia, or thrombocytopenia, respectively. Dose-limiting neutropenia was seen in three of five patients treated with topotecan 1.5 mg/m(2) and paclitaxel 175 mg/m(2). Therefore, topotecan 1.5 mg/m(2) with paclitaxel 135 mg/m(2) was determined to be the maximum tolerated dose. Of the 17 evaluable patients, 53% achieved a partial response and 18% achieved stable disease. In summary, we have identified a regimen of topotecan 1.5 mg/m(2) and paclitaxel 135 mg/m(2) that was well tolerated and active in this patient group. Additional studies of topotecan and paclitaxel at these dose levels are needed to fully elucidate the efficacy of this combination in extensive SCLC.

Topoisomerase I interactive agents

Increased insight into the mechanism of interaction of topoisomerase I interactive agents will maximize the therapeutic index and enhance the development of additional agents. Preclinical studies designed to elucidate mechanisms by which the topoisomerase I interactive agents induce cell death will be essential. The role of ABC transporters in resistance to topoisomerase I interactive agents has been recently appreciated and future studies should be directed at circumventing this resistance. The results of preclinical studies must be translated into the design of clinical trials so that these agents can be used rationally. In this regard results of preclinical studies have clearly pointed to the enhanced antitumor activity from protracted dosing of topoisomerase I interactive agents and results of clinical trials are now supporting these preclinical findings. Finally, investigators are trying to understand better the mechanism(s) of the dose-limiting toxicities observed with the currently available topoisomerase I interactive agents in an effort to enable the optimal dosing of these agents. Even though the first priority must be to determine the therapeutic potential of the currently available agents, it is reassuring to know that other topoisomerase I interactive agents are currently under development.

Emerging role of topotecan in front-line treatment of carcinoma of the ovary

The conventional front-line chemotherapy strategy for advanced epithelial ovarian carcinoma has become adjuvant administration of platinum (carboplatin and cisplatin), either alone or, most often, in combination with a taxane. However, a number of active agents have been identified in phase II/III trials of second-line and salvage ovarian cancer patients that may augment this front-line strategy. One agent, topotecan, has antitumor activity comparable with paclitaxel in patients with recurrent ovarian cancer and is an established treatment in second-line or salvage settings. Additionally, its mechanism of action is different from paclitaxel and is nonoverlapping. These properties, coupled with the in vitro synergy observed in tumor models among topotecan, paclitaxel, and platinum, have provided the rationale for investigators to examine topotecan in front-line ovarian cancer therapy. A number of strategies for incorporating topotecan into front-line therapy are under active investigation, including the replacement of paclitaxel with topotecan, a triplet regimen with cisplatin or carboplatin and paclitaxel, a consolidation regimen consisting of several courses of a platinum agent and paclitaxel followed by several courses of topotecan, and a sequential doublet regimen in which patients receive platinum in every course as part of a doublet with alternating or sequential topotecan and paclitaxel. Preliminary data from ongoing clinical trials of these new regimens show favorable response rates and generally manageable toxicity profiles. This review summarizes the preliminary clinical findings associated with the four strategies and outlines ongoing and future randomized studies of topotecan in front-line ovarian cancer.