Smart bombs versus blunderbusses: high-dose chemotherapy for breast cancer

Impact of intertumoral heterogeneity on predicting chemotherapy response of BRCA1-deficient mammary tumors

The lack of markers to predict chemotherapy responses in patients poses a major handicap in cancer treatment. We searched for gene expression patterns that correlate with docetaxel or cisplatin response in a mouse model for breast cancer associated with BRCA1 deficiency. Array-based expression profiling did not identify a single marker gene predicting docetaxel response, despite an increase in Abcb1 (P-glycoprotein) expression that was sufficient to explain resistance in several poor responders. Intertumoral heterogeneity explained the inability to identify a predictive gene expression signature for docetaxel. To address this problem, we used a novel algorithm designed to detect differential gene expression in a subgroup of the poor responders that could identify tumors with increased Abcb1 transcript levels. In contrast, standard analytical tools, such as significance analysis of microarrays, detected a marker only if it correlated with response in a substantial fraction of tumors. For example, low expression of the Xist gene correlated with cisplatin hypersensitivity in most tumors, and it also predicted long recurrence-free survival of HER2-negative, stage III breast cancer patients treated with intensive platinum-based chemotherapy. Our findings may prove useful for selecting patients with high-risk breast cancer who could benefit from platinum-based therapy.

Genomic instability in breast and ovarian cancers: translation into clinical predictive biomarkers

Breast and ovarian cancer are among the most common malignancies diagnosed in women worldwide. Together, they account for the majority of cancer-related deaths in women. These cancer types share a number of features, including their association with hereditary cancer syndromes caused by heterozygous germline mutations in BRCA1 or BRCA2. BRCA-associated breast and ovarian cancers are hallmarked by genomic instability and high sensitivity to DNA double-strand break (DSB) inducing agents due to loss of error-free DSB repair via homologous recombination (HR). Recently, poly(ADP-ribose) polymerase inhibitors, a new class of drugs that selectively target HR-deficient tumor cells, have been shown to be highly active in BRCA-associated breast and ovarian cancers. This finding has renewed interest in hallmarks of HR deficiency and the use of other DSB-inducing agents, such as platinum salts or bifunctional alkylators, in breast and ovarian cancer patients. In this review we discuss the similarities between breast and ovarian cancer, the hallmarks of genomic instability in BRCA-mutated and BRCA-like breast and ovarian cancers, and the efforts to search for predictive markers of HR deficiency in order to individualize therapy in breast and ovarian cancer.

An aCGH classifier derived from BRCA1-mutated breast cancer and benefit of high-dose platinum-based chemotherapy in HER2-negative breast cancer patients

BACKGROUND

Breast cancer cells deficient for BRCA1 are hypersensitive to agents inducing DNA double-strand breaks (DSB), such as bifunctional alkylators and platinum agents. Earlier, we had developed a comparative genomic hybridisation (CGH) classifier based on BRCA1-mutated breast cancers. We hypothesised that this BRCA1-like(CGH) classifier could also detect loss of function of BRCA1 due to other causes besides mutations and, consequently, might predict sensitivity to DSB-inducing agents.

PATIENTS AND METHODS

We evaluated this classifier in stage III breast cancer patients, who had been randomly assigned between adjuvant high-dose platinum-based (HD-PB) chemotherapy, a DSB-inducing regimen, and conventional anthracycline-based chemotherapy. Additionally, we assessed BRCA1 loss through mutation or promoter methylation and immunohistochemical basal-like status in the triple-negative subgroup (TN subgroup).

RESULTS

We observed greater benefit from HD-PB chemotherapy versus conventional chemotherapy among patients with BRCA1-like(CGH) tumours [41/230 = 18%, multivariate hazard ratio (HR) = 0.12, 95% confidence interval (CI) 0.04-0.43] compared with patients with non-BRCA1-like(CGH) tumours (189/230 = 82%, HR = 0.78, 95% CI 0.50-1.20), with a significant difference (test for interaction P = 0.006). Similar results were obtained for overall survival (P interaction = 0.04) and when analyses were restricted to the TN subgroup. Sixty-three percent (20/32) of assessable BRCA1-like(CGH) tumours harboured either a BRCA1 mutation (n = 8) or BRCA1 methylation (n = 12).

CONCLUSION

BRCA1 loss as assessed by CGH analysis can identify patients with substantially improved outcome after adjuvant DSB-inducing chemotherapy when compared with standard anthracycline-based chemotherapy in our series.

High dose chemotherapy with autologous hematopoietic stem cell support for solid tumors other than breast cancer in adults

Since the early 1980s high dose chemotherapy with autologous hematopoietic stem cell support was adopted by many oncologists as a potentially curative option for solid tumors, supported by a strong rationale from laboratory studies and apparently convincing results of early phase II studies. As a result, the number and size of randomized trials comparing this approach with conventional chemotherapy initiated (and often abandoned before completion) to prove or disprove its value was largely insufficient. In fact, with the possible exception of breast carcinoma, the benefit of a greater escalation of dose of chemotherapy with stem cell support in solid tumors is still unsettled and many oncologists believe that this approach should cease. In this article, we critically review and comment on the data from studies of high dose chemotherapy so far reported in adult patients with small cell lung cancer, ovarian cancer, germ cell tumors and sarcomas.

A multicenter randomized clinical trial evaluating interleukin-2 activated hematopoietic stem cell transplantation and post-transplant IL-2 for high risk breast cancer patients

PURPOSE

This Phase III randomized multicenter trial compared progression-free (PFS) and overall survival (OS) for autologous peripheral blood stem cell (aPBSC) transplantation with or without immunotherapy in high-risk breast cancer patients.

METHODS

Eligible patients had American Joint Committee on Cancer (AJCC) 5th Edition Stage II/IIIA with > or = 4 axillary nodes, Stage IIIB, or chemotherapy-sensitive or stable Stage IV disease. Following treatment with cyclophosphamide, thiotepa and carboplatin (STAMP V), patients were randomized to aPBSC transplant with or without immunotherapy. Patients on immunotherapy received cells that were incubated in interleukin-2 (IL-2) for 24 h followed by parenteral IL-2 for 5 days then 2 days of rest for 4 weeks.

RESULTS

Fifty-nine patients were treated (35 Stage II/IIIA; 13 Stage IIIB; 11 Stage IV), 30 patients were randomized to immunotherapy and 29 patients to no immunotherapy. Neutrophils engrafted a median of 10 days post-transplant in both groups. The median times to platelet engraftment were 9 and 10 days after transplant in the no-immunotherapy and immunotherapy groups, respectively (p = 0.03). There was no statistical evidence (p = 0.61) of a difference in progression-free and surviving (PFS) at 3 years for patients receiving immunotherapy (53%) compared with no immunotherapy (48%). There was some evidence of superiority in overall survival (OS) at 3 years for patients receiving immunotherapy (83%) compared with no immunotherapy (69%), but the difference between survival curves was not statistically significant (p = 0.08). Also, there was some evidence that patients developing acute graft versus host disease (aGVHD) had superior PFS (p = 0.02) but not OS (p = 0.19) than patients not developing aGVHD. Toxicities were transient and similar between groups, with no treatment-related deaths.

CONCLUSIONS

This phase III study of high-risk breast cancer patients randomized to immunotherapy or no immunotherapy demonstrated that a well-tolerated immunotherapy regimen added to aPBSC transplant did not improve PFS, but there was some improvement in OS, but not by an amount that was statistically significant (p = 0.08).