Topotecan in patients with BRCA-associated and sporadic platinum-resistant ovarian, fallopian tube, and primary peritoneal cancers

Molecular tests for prediction of tumor sensitivity to cytotoxic drugs

Chemotherapy constitutes the backbone of cancer treatment. Several predictive assays assist personalized administration of cytotoxic drugs and are recommended for use in a clinical setting. The deficiency of DNA repair by homologous recombination (HRD), which is caused by inactivation of BRCA1/2 genes or other genetic events, is associated with high tumor responsiveness to platinum compounds, bifunctional alkylating agents and topoisomerase II poisons. Low activity of MGMT predicts the efficacy of nitrosoureas and tetrazines. Some clinically established pharmacogenetic tests allow for the adjustment of drug dosage, for example, the analysis of DPYD allelic variants for administration of fluoropyrimidines and UGT1A1 genotyping for the use of irinotecan. While there are promising molecular predictors of tumor sensitivity to pemetrexed, gemcitabine and taxanes, they remain in the investigational stage and require additional validation. Comprehensive molecular analysis of tumors obtained from drug responders and non-responders is likely to reveal new clinically useful predictive markers for cytotoxic therapy.

How Cancer Cells Resist Chemotherapy: Design and Development of Drugs Targeting Protein-Protein Interactions

Background:

Resistance toward chemotherapeutics is one of the main obstacles on the way to effective cancer treatment. Personalization of chemotherapy could improve clinical outcome. However, despite preclinical significance, most of the potential markers have failed to reach clinical practice partially due to the inability of numerous studies to estimate the marker’s impact on resistance properly.

Objective:

The analysis of drug resistance mechanisms to chemotherapy in cancer cells, and the proposal of study design to identify bona fide markers.

Methods:

A review of relevant papers in the field. A PubMed search with relevant keywords was used to gather the data. An example of a search request: drug resistance AND cancer AND paclitaxel.

Results:

We have described a number of drug resistance mechanisms to various chemotherapeutics, as well as markers to underlie the phenomenon. We also proposed a model of a rational-designed study, which could be useful in determining the most promising potential biomarkers.

Conclusion:

Taking into account the most reasonable biomarkers should dramatically improve clinical outcome by choosing the suitable treatment regimens. However, determining the leading biomarkers, as well as validating of the model, is a work for further investigations.

Association of BRCA1/2 mutations with ovarian cancer prognosis: An updated meta-analysis

OBJECTIVE

A meta-analysis was performed to determine if BRCA1/2 mutations are associated with improved overall survival (OS) and progression-free survival (PFS) in patients with ovarian cancer.

RESEARCH DESIGN AND METHODS

Studies of patients with primary or recurrent ovarian cancer that examined the relationship between BRCA1/2 mutation status and outcomes were included.

MAIN OUTCOME MEASURES

The primary outcomes were OS and PFS of patients with and without BRCA1 and BRCA2 mutations. The secondary outcome was treatment response: complete response, partial response, and overall response.

RESULTS

Overall analysis revealed BRCA1/2 mutations were associated with improved OS [hazard ratio (HR) = 0.75; 95% confidence interval (CI): 0.64, 0.88; P < .001] and PFS (HR = 0.80; 95% CI: 0.64, 0.99; P = .039). BRCA1 mutations were significantly associated with improved OS (HR = 0.75) but not PFS, and BRCA2 mutations alone were not associated with either improved OS or PFS. The presence of BCRA1/2 mutations was associated with a better overall response rate, higher complete response rate, and lower partial response rate; however, BRCA1 or BRCA2 alone was not associated with overall response rate.

CONCLUSIONS

BRCA1 mutations appear to be associated with improved OS in patients with ovarian cancer. However, the effect of BRCA1 mutations on PFS and BRCA2 mutations alone on OS and PFS is less clear.

Chemotherapy for Patients with BRCA1 and BRCA2-Mutated Ovarian Cancer: Same or Different?

Retrospective studies have shown an improved prognosis, higher response rates to platinum-containing regimens, and longer treatment-free intervals between relapses in patients with BRCA 1 and BRCA 2 (BRCA1/2)-mutated ovarian cancer (BMOC) compared with patients who are not carriers of this mutation. These features of BMOC are attributed to homologous-recombination repair (HR) deficiency in the absence of BRCA1/2 function, which results in an impaired ability of tumor cells to repair platinum-induced double-strand breaks (DSBs), thereby conferring increased chemosensitivity and increased sensitivity to poly(ADP-ribose) polymerase (PARP) enzyme inhibition and other DNA-damaging chemotherapeutic agents such as pegylated liposomal doxorubicin (PLD). Therefore, the chemotherapeutic approach for patients with BMOC should focus on treatment with platinum-based chemotherapy at first-line and recurrent-disease settings and measures to increase the platinum-free interval following early platinum-resistant relapse (i.e., progression-free survival of less than 6 months from last platinum-based chemotherapy) by using nonplatinum cytotoxic agents, with the aim of reintroducing platinum again at a later date. The role of first-line intraperitoneal platinum-based therapy in the specific context of BMOC also merits further analysis. Other than platinum, alternative DNA-damaging agents (including PLD and trabectedin) also may have a therapeutic role in patients with recurrent BMOC. The recent approval of olaparib for clinical use in Europe and the United States will also affect chemotherapeutic strategies for these patients. Further work to clarify the precise relationship between BRCA1/2 mutation genotype and clinical phenotype is crucial to delineating the optimal therapeutic choices in the future for patients with BMOC.

Systemic treatment for hereditary cancers: a 2012 update

The history of specific therapy for hereditary tumors dates back to mid 1980s and involves a number of reports demonstrating regression of familial colon polyps upon administration of sulindac. Virtually no clinical studies on other hereditary cancer types were available until the year 2009, when Byrski et al. presented the data on unprecedented sensitivity of BRCA1-associated breast malignancies to cisplatin. This breakthrough has revived interest to the treatment of cancer in germ-line mutation carriers. Recent trials and clinical observations have confirmed the efficacy of platinating agents and PARP inhibitors in BRCA1/2-driven breast, ovarian and pancreatic carcinomas. Pegylated liposomal doxorubicin may be considered as a promising treatment option for BRCA1/2-related ovarian cancer after the failure of platinum-containing therapy. Several novel drugs have been recently introduced in the management of rare familial tumor syndromes. Vandetanib, a low-molecular weight RET kinase inhibitor, demonstrated substantial efficacy in the treatment of hereditary and sporadic medullary thyroid cancer. Vismodegib, an inhibitor of SMO oncoprotein, caused regression of basal-cell carcinomas in patients with Gorlin syndrome. Down-regulation of mTOR kinase by everolimus has been successfully used for the therapy of subependymal giant-cell astrocytomas in patients with tuberous sclerosis. The achievements in the prevention, diagnostics and treatment of hereditary cancers may serve as an excellent example of triumph of translational medicine.

Weekly Topotecan for Recurrent Ovarian, Fallopian Tube and Primary Peritoneal Carcinoma: Tolerability and Efficacy Study—The Israeli Experience

Objectives

The purpose of this study was to assess the clinical activity and toxicity of weekly topotecan in a large cohort of epithelial ovarian (EOC), primary peritoneal (PPC), and tubal cancer patients.

Methods

Records of patients with recurrent EOC, PPC, and tubal cancer who were treated with weekly topotecan (4.0 mg/m2 on days 1, 8, and 15 on a 28-day cycle) after failure of more than 1 prior regimen were retrospectively reviewed in 8 centers in Israel.

Results

Two hundred four patients were evaluated for efficacy and toxicity. Median age was 62 years (range, 27–89 years); 121 (59.3%) were platinum sensitive. Patients were exposed to a median of 2 previous lines (range, 1–9), and 48.5% received only 1 prior chemotherapy regimen. Median follow-up was 15.5 months (range, 2.5–112 months). Overall response rate was 26.5%, of which 11 patients (5.4%) had complete response, and 43 patients (21.1%) had partial response. Clinical benefit rate (complete response + partial response + stable disease) was 65.7%. Median progression-free survival was 4.0 months (95% confidence interval [CI], 3.5–4.5 months). There was no significant difference between platinum-sensitive and platinum-resistant patients regarding response rate or progression-free survival. Median overall survival from disease diagnosis was 45.0 months (95% CI, 40.04–49.6 months) and 16.0 months (95% CI, 12.3–19.7 months) from initiation of topotecan therapy. Overall survival was significantly different between patients with platinum-sensitive and platinum-resistant disease (19.9 vs 10.8 months, respectively, P = 0.003; 95% CI, 8.1–16.3 months). Multivariate analysis showed that only platinum sensitivity and topotecan line were associated with overall survival. Weekly topotecan was well tolerated—with only 16.7% of patients experiencing grade 3 to 4 hematologic toxicities. There were no other grade 4 toxicities, and only 6.9% grade 3 toxicities.

Conclusions

In this large cohort of recurrent EOC, PPC, and tubal cancer, weekly topotecan was well tolerated with good clinical benefit rate, comparable to previous studies.

Therapeutic intervention by the simultaneous inhibition of DNA repair and type I or type II DNA topoisomerases: one strategy, many outcomes

Many anticancer drugs reduce the integrity of DNA, forming strand breaks. This can cause mutations and cancer or cell death if the lesions are not repaired. Interestingly, DNA repair-deficient cancer cells (e.g., those with BRCA1/2 mutations) have been shown to exhibit increased sensitivity to chemotherapy. Based on this observation, a new therapeutic approach termed 'synthetic lethality' has been developed, in which radiation therapy or cytotoxic anticancer agents are employed in conjunction with selective inhibitors of poly(ADP-ribose)polymerase-1 (PARP-1). Such combinations can cause severe genomic instability in transformed cells resulting in cell death. The synergistic effects of combining PARP-1 inhibition with anticancer drugs have been demonstrated. However, the outcome of this therapeutic strategy varies significantly between cancer types, suggesting that synthetic lethality may be influenced by additional cellular factors. This review focuses on the outcomes of the combined action of PARP-1 inhibitors and agents that affect the activity of DNA topoisomerases.