Much ado about not...enough data: high-dose chemotherapy with autologous stem cell rescue for breast cancer

Comparative effectiveness research: moving medical oncology forward

Comparative effectiveness research (CER) is critically needed in medical oncology to improve the care being delivered to oncology patients. As medical oncologists are forced to rely on insufficient data as a part of daily treatment decision making, and as the cancer treatment landscape evolves quickly relative to other areas of medicine, CER is particularly pressing in our field. Continued reliance on randomized clinical trials is a part of the solution, but it cannot be the sole answer. As new and richer data sources become available addressing quality of life, resource utilization, and other critical elements, the implementation of CER will advance. Its true power will lie in linkages to "learning health systems" and real-time application to the day-to-day practice of medicine.

Assessing causal relationships between treatments and clinical outcomes: always read the fine print

Changes in clinical practice should be driven by relevant and reliable evidence. Hence, adoption of a new therapy requires demonstrating that it provides (causes) benefit. Such evidence is generally obtained from intent-to-treat analyses of randomized clinical trials (RCTs). In this paper, we review other approaches to assessing the causal relationship between treatments and outcomes: (1) inference from non-randomized (observational) studies, (2) analysis of randomized studies where patients received treatments other than those to which they were randomized and (3) analysis of studies where the outcome of interest is sometimes unobservable because of a competing event (competing risks). We conclude that for the practice-changing demonstration of a favorable benefit-to-risk ratio, the gold standard is the intent-to-treat analysis of RCTs. At the same time, we illustrate how careful application of special statistical methods for assessment of treatment-outcome causation can be instrumental in complementing existing randomized evidence and guiding design of future research.

Economic analysis of conventional-dose chemotherapy compared with high-dose chemotherapy plus autologous hematopoietic stem-cell transplantation for metastatic breast cancer

We performed an economic analysis of data from 180 women in a clinical trial of conventional-dose chemotherapy vs high-dose chemotherapy plus stem-cell transplantation for metastatic breast cancer responding to first-line chemotherapy. Data on resource use, including hospitalizations, medical procedures, medications, and diagnostic tests, were abstracted from subjects' clinical trial records. Resources were valued using the Medicare Fee Schedule for inpatient costs at one academic medical center and average wholesale prices for medications. Monthly costs were calculated and stratified by treatment group and clinical phase. Mean follow-up was 690 days in the transplantation group and 758 days in the conventional-dose chemotherapy group. Subjects in the transplantation group were hospitalized for more days (28.6 vs 17.8, P=0.0041) and incurred higher costs (US dollars 84055 vs US dollars 28169) than subjects receiving conventional-dose chemotherapy, with a mean difference of US dollars 55886 (95% CI, US dollars 47298-US dollars 63666). Sensitivity analyses resulted in cost differences between the treatment groups from US dollars 36528 to US dollars 75531. High-dose chemotherapy plus stem-cell transplantation resulted in substantial additional morbidity and costs at no improvement in survival. Neither the survival results nor the economic findings support the use of this procedure outside of the clinical trial setting.

Genetic protection of repopulating hematopoietic cells with an improved MDR1-retrovirus allows administration of intensified chemotherapy following stem cell transplantation in mice

This study was undertaken to analyze the hematotoxicity of paclitaxel (Taxol) and to test whether transduction of repopulating hematopoietic cells with a retroviral vector (SF1m) expressing the human multidrug resistance 1 gene (MDR1) would permit dose intensification following bone marrow transplantation (BMT). While the regimen chosen (8 x 20 mg/kg i.p. within 12 days) produced a non-lethal, reversible hematotoxicity in mice with steady-state hematopoiesis, only 35.3% (6/17) of control mice survived when treated starting 14 days post BMT. In contrast, 83.3% (15/18) of mice transplanted with SF1m-transduced cells survived, owing to a significant protection against severe acute myelotoxicity (as determined by neutrophil counts, white and red blood cell counts and values for hemoglobin and hematocrit). After recovery from chemotherapy, an increase of myeloid cells that were resistant to colchicine and effluxed the fluorochrome Rhodamine 123 was observed in SF1m-mice, but not in controls. These results reveal that the lethal, dose-limiting hematotoxicity of an intensified post-transplantation chemotherapy with paclitaxel can be prevented by retroviral transfer of the MDR1 gene to a minor proportion of repopulating cells. Our mouse model, mimicking clinically achievable gene transfer rates, thus suggests that bone marrow chemoprotection may widen the therapeutic window and permit an earlier onset of post-transplantation chemotherapy.

High-dose versus standard chemotherapy in metastatic breast cancer: comparison of Cancer and Leukemia Group B trials with data from the Autologous Blood and Marrow Transplant Registry

PURPOSE

To assess survival of patients with metastatic breast cancer treated with high-dose chemotherapy (HDC) versus standard-dose chemotherapy (SDC).

PATIENTS AND METHODS

SDC in four Cancer and Leukemia Group B (CALGB) trials was compared with hematopoietic stem-cell support in patients from the Autologous Blood and Marrow Transplant Registry. Cox proportional hazard regression incorporated potentially confounding effects. A total of 1,509 women were enrolled onto CALGB trials, and 1,188 women received HDC. No significant survival differences existed by CALGB trial or HDC regimen. Consideration was restricted to candidates for both SDC and HDC. The resulting sample included 635 SDC and 441 HDC patients. The outcome of interest was overall survival.

RESULTS

The HDC group displayed better performance status. The SDC group had slightly better survival in first year after treatment. The HDC group had lower hazard of death from years 1 to 4 and had somewhat higher probability of 5-year survival (adjusted probabilities [95% confidence intervals], 23% [17% to 29%] v 15% [11% to 19%], P =.03).

CONCLUSION

After controlling for known prognostic factors in this nonrandomized analysis of two large independent data sets, women receiving HDC versus SDC for metastatic breast cancer have a similar short-term probability of survival, and might have a modestly higher long-term probability of survival.

Serum cardiac troponin I levels and ECG/Echo monitoring in breast cancer patients undergoing high-dose (7 g/m(2)) cyclophosphamide

High-dose cyclophosphamide (HD-CTX) is largely employed in high-dose chemotherapy (HD-CHT) protocols. HD-CTX dose-limiting toxicity expresses itself as cardiac toxicity which is fatal in a minority of patients. The pathophysiology of HD-CTX-associated cardiotoxicity is still poorly understood. Autopsy studies in patients who died from acute HD-CTX-induced cardiac toxicity revealed hemorrhagic myocardial cell death and interstitial edema. Recently troponins, in particular troponin I (cTnI), have been found to represent a uniquely sensitive and specific marker of myocyte membrane integrity and therefore to increase in response to minimal myocardial cell damage in different settings, including doxorubicin-induced cardiotoxicity. We performed a multiparametric cardiologic monitoring in 16 consecutive breast cancer patients undergoing HD-CTX by means of serial ECG registrations and cardiac enzymes (CPK, CPK-MB and cTnI) determinations plus echocardiography in order to clarify acute cardiac events following HD-CTX administration. Neither overt cardiac toxicity nor cardiac enzymes elevation were recorded. Serial ECGs revealed in six cases little and reversible reduction of QRS voltage and/or ST abnormalities. Echo monitoring showed in four cases mild and transient increase of LV diastolic/systolic diameter/volume without decrease of FS% or EF% below normal values: in two of them abnormalities of diastolic function (E/A mitral doppler ratio) were also recorded. We conclude that our protocol of HD-CTX administration does not cause myocardial cell damage as analyzed by serum cTnI levels, thus suggesting that myocyte membrane injury may not be the first direct mechanism of HD-CTX cardiotoxicity. ECG (ie QRS voltages ) and Echo (ie E/A ratio) monitoring leads us to hypothesize that slight interstitial edema with reduction of LV diastolic compliance may be initial signs of cardiac dysfunction in this clinical setting.

Long-term prognosis of breast cancer patients with 10 or more positive lymph nodes treated with CMF

The purpose of this investigation was to study the long-term prognosis of breast cancer patients with 10 or more positive lymph nodes after conventional chemotherapy treatment with cyclophosphamide, methotrexate and 5-fluorouracil (CMF). Between 1984 and 1989, 1048 node-positive patients were treated with CMF in two separate trials conducted by the German Breast Cancer Study Group (GBSG). Subgroups either received radiotherapy or tamoxifen in addition. In this study, long-term prognosis in the subgroup of 141 patients with 10 or more positive lymph nodes was investigated. Univariate and multivariate Cox models were used to evaluate the effect of prognostic factors on event-free survival (EFS) and overall survival (OS). Both univariate and multivariate analyses revealed the progesterone receptor (PR) status as the dominating prognostic factor for both EFS and OS, resulting in a strongly increased risk of more than 2-fold for receptor-negative patients. A large number of positive lymph nodes also affected the prognosis for EFS. In univariate analysis, the degree of lymph node involvement (i.e. percentage of positive nodes out of all examined nodes), oestrogen status (ER) status, and tumour grade also showed significant effects. To conclude, the prognosis in the subgroup of patients with 10 or more positive lymph nodes is heterogeneous. Some surprisingly high survival rates have been observed in case series of breast cancer patients treated with high-dose chemotherapy which may be explained by patient selection. From the usual factors investigated in this study, the PR status showed the strongest effect, and, at least this factor should be taken into account in the design and analysis of trials for breast cancer patients with a poor prognosis.

Comparison of double and triple high-dose chemotherapy with autologous blood stem cell transplantation in patients with metastatic breast cancer

In patients with metastatic breast cancer (MBC), early dose intensification with multiple cycles of peripheral blood stem cell-supported high-dose chemotherapy (HDCT) seems superior to a late dose-intensification strategy. We compared the progression-free survival (PFS) and overall survival (OS) of 20 patients treated with a double (D)-HDCT regimen to 20 patients who received a triple (T)-HDCT, matched by age, estrogen receptor (ER) status, adjuvant chemotherapy, initial disease-free interval, predominant metastatic site, and number of metastatic sites. At a median follow-up of 41.5 months (range, 14-88 months) an intent-to-treat analysis showed no difference in PFS (p = 0.72) and OS (p = 0.93) between the matched patients. For all 76 patients treated within the D- or T-HDCT trial, median PFS and OS was 13 months (range, 2-78 months) and 24.5 months (range, 7-78 months), respectively. In multivariate analysis independent predictors of shorter OS included negative ER (relative risk [RR] = 3.0 [95% confidence interval (CI) 1.5-5.9]; p = 0.002), more than two metastatic sites (RR = 2.4 [95% CI 1.0-5.7]; p = 0.049) and failure to achieve complete remission/no evidence of disease (CR/NED) after HDCT (RR = 4.5 [95% CI 2.0-10.1]; p < 0.0001). These data show that early dose intensification with T-HDCT is not superior to a D-HDCT regimen in patients with MBC. ER-negative tumors, more than two metastatic sites and no CR/NED after HDCT, are associated with inferior outcome.

Three different stable human breast adenocarcinoma sublines that overexpress ALDH3A1 and certain other enzymes, apparently as a consequence of constitutively upregulated gene transcription mediated by transactivated EpREs (electrophile responsive elements) present in the 5'-upstream regions of these genes

ALDH3A1 catalyzes the detoxification of cyclophosphamide, mafosfamide, 4-hydroperoxycyclophosphamide and other oxazaphosphorines. Constitutive ALDH3A1 levels, as well as those of certain other drug-metabolizing enzymes, e.g. NQO1 and CYP1A1, are relatively low in cultured, relatively oxazaphosphorine-sensitive, human breast adenocarcinoma MCF-7 cells. However, transient cellular insensitivity to the oxazaphosphorines can be brought about in these cells by transiently elevating ALDH3A1 levels in them as a consequence of transient exposure to: (1) electrophiles such as catechol that induce the transcription of a battery of genes, e.g. ALDH3A1 and NQO1, having in common an electrophile responsive element (EpRE) in their 5'-upstream regions; or (2) Ah-receptor agonists, e.g. indole-3-carbinol and polycyclic aromatic hydrocarbons such as 3-methylcholanthrene, that induce the transcription of a battery of genes, e.g. ALDH3A1, NQO1 and CYP1A1, having in common a xenobiotic responsive element (XRE) in their 5'-upstream regions. Further, MCF-7 sublines that are constitutively, i.e. when grown in the absence of the original selecting pressure, relatively oxazaphosphorine-insensitive as a consequence of constitutively relatively elevated cellular ALDH3A1 levels evolved when MCF-7 cells were: (1) continuously exposed for several months to gradually increasing concentrations of 4-hydroperoxycyclophosphamide or benz(a)pyrene; or (2) briefly exposed (once for 30 min) to a high concentration (1 mM) of mafosfamide. Each of these three stable sublines is constitutively relatively cross-insensitive to benz(a)pyrene and other polycyclic aromatic hydrocarbons. Cellular levels of NQO1, but not of CYP1A1, are also constitutively relatively elevated in each of the three sublines. RT-PCR-based experiments established that ALDH3A1 mRNA levels are constitutively elevated ( approximately 5- to 8-fold) in each of the three sublines. The elevated ALDH3A1 mRNA levels are not the consequence of gene amplification, hypomethylation of a relevant regulatory element, or ALDH3A1 mRNA stabilization. Collectively, these observations suggest that constitutively elevated levels of ALDH3A1 and certain other enzymes in the three stable sublines are probably the consequence of a constitutive change in the cellular concentration of a key component of the EpRE signaling pathway, such that the cellular concentration of the relevant ultimate transactivating factor is constitutively elevated, i.e. gene transcription promoted by transactivated EpREs is constitutively upregulated. Further, constitutively upregulated gene transcription mediated by transactivated EpREs can be relatively easily induced, whereas that mediated by transactivated XREs cannot, at least in MCF-7 cells. Still further, the three sublines may facilitate study of the signaling pathway that leads to transactivation of the EpREs present in the 5'-upstream regions of ALDH3A1, NQO1 and other gene loci.

Autologous graft-versus-host disease induction in advanced breast cancer: role of peripheral blood progenitor cells

The purpose of the present study was to investigate the impact of the use of peripheral blood progenitor cells (PBPCs) on the induction of autologous graft-versus-host disease (GVHD) in patients with advanced breast cancer. 14 women with stage IIIB and 36 women with stage IV breast cancer received cyclosporine (CsA) 2.5 mg kg-1 i.v. daily, d 0-28, and interferon-gamma (IFNg) 0.025 mg/m2 s.c. qod, d7-28, following PBPC-T +/- bone marrow transplantation (BMT). Preceding high-dose chemotherapy consisted of cyclophosphamide 6 g/m2 and thiotepa 800 mg/m2. Histologically proven > or = grade II cutaneous GVHD was induced in18/50 (36%) of patients and was independent of the source of haematopoietic support. In vitro studies showed that post-transplant, 76% of patients had developed auto-cytotoxicity against their own pre-transplant PHA-lymphoblasts. A significant correlation between the occurrence of GVHD > or = grade II and cytolysis was observed in the NK cell-line K562 and the T47D breast cancer cell-line. With a median follow-up of 2(1/2) years, the overall survival (OS) is 58%, the disease-free survival (DFS) 26%, both independent of the development of GVHD and similar to what has been observed in other studies on high-dose chemotherapy in advanced breast cancer. It therefore remains unclear whether the induction of autologous GVHD with the occurrence of auto-cytotoxic lymphocytes can result in an anti-tumour effect in this group of patients.

High-dose chemotherapy with hematopoietic stem-cell transplantation for breast cancer: current status, future trends

High-dose chemotherapy with hematopoietic stem-cell transplantation (HDC/HSCT) has been extensively studied as a potential treatment for breast cancer. A literature search of MEDLINE from January 1990 through December 1999 identified 497 published full papers. Of these articles, 120 reported the results of clinical trials, 78 were reviews, and 299 reported on issues related to the technology of peripheral stem cells, supportive care, and toxicity. The phase II data must be interpreted with caution, as it is subject to selection bias; transplant recipients tended to be younger, rigorously staged, and selected to be chemotherapy responsive. There continues to be controversy regarding the role of high-dose therapy in this disease. Only a few fully published randomized trials are available; these studies were powered only to detect large differences in survival and no benefit was shown. Several large controlled trials are either in progress or are too early for definitive analysis. This review analyzes the current literature on HDC/HSCT for breast cancer, identifying prognostic factors and discussing ongoing research designed to improve antitumor effects.

Further evaluation of intensified and increased total dose of cyclophosphamide for the treatment of primary breast cancer: findings from National Surgical Adjuvant Breast and Bowel Project B-25

PURPOSE

In 1989, the National Surgical Adjuvant Breast and Bowel Project initiated the B-22 trial to determine whether intensifying or intensifying and increasing the total dose of cyclophosphamide in a doxorubicin-cyclophosphamide combination would benefit women with primary breast cancer and positive axillary nodes. B-25 was initiated to determine whether further intensifying and increasing the cyclophosphamide dose would yield more favorable results.

PATIENTS AND METHODS

Patients (n = 2,548) were randomly assigned to three groups. The dose and intensity of doxorubicin were similar in all groups. Group 1 received four courses, ie, double the dose and intensity of cyclophosphamide given in the B-22 standard therapy group; group 2 received the same dose of cyclophosphamide as in group 1, administered in two courses (intensified); group 3 received double the dose of cyclophosphamide (intensified and increased) given in group 1. All patients received recombinant human granulocyte colony-stimulating factor. Life-table estimates were used to determine disease-free survival (DFS) and overall survival.

RESULTS

No significant difference was observed in DFS (P =.20), distant DFS (P =.31), or survival (P =.76) among the three groups. At 5 years, the DFS in groups 1 and 2 (61% v 64%, respectively; P =. 29) was similar to but slightly lower than that in group 3 (61% v 66%, respectively; P = 08). Survival in group 1 was concordant with that in groups 2 (78% v 77%, respectively; P =.71) and 3 (78% v 79%, respectively; P =.86). Grade 4 toxicity was 20%, 34%, and 49% in groups 1, 2, and 3, respectively. Severe infection and septic episodes increased in group 3. The decrease in the amount and intensity of cyclophosphamide and delays in therapy were greatest in courses 3 and 4 in group 3. The incidence of acute myeloid leukemia increased in all groups.

CONCLUSION

Because intensifying and increasing cyclophosphamide two or four times that given in standard clinical practice did not substantively improve outcome, such therapy should be reserved for the clinical trial setting.

Metastatic breast cancer

The unfortunate reality of metastatic breast cancer is that all treatment is palliative in nature. This is a disease that currently has no cure and for which therapy is directed towards accentuating survival and relieving symptoms. Current technology allows the prediction and detection of metastases earlier and with greater accuracy. These achievements need to be consolidated by the discovery of innovative therapies that can alter the inevitable outcome of this disease.

Methodological arguments for the necessity of randomized trials in high-dose chemotherapy for breast cancer

In the past ten years high-dose chemotherapy with autologous haematopoietic stem-cell support (HD-CT) has increasingly been used for breast cancer. But the vast majority of trials are small phase I/II studies showing until now not enough evidence that HD-CT is superior to conventional-dose chemotherapy (CD-CT). In contrast to this, the public perception of this treatment is different. Patients as well as physicians often uncritically believe in reports contrasting the positive results obtained in case series treated by HD-CT with those of historical control groups. This leads to the problem that many patients and also clinicians are not willing to participate in randomized trials on this topic. A critical assessment of current knowledge on the effectiveness of HD-CT in breast cancer is given. The problems related to the use of historical controls, in general, and especially in the setting of HD-CT are demonstrated. Using data of patients treated with CD-CT within trials of the German Breast Cancer Study Group (GBSG) it will be shown that results similarly favorable to those reported from patients treated with a high-dose regimen may be produced using quite simple selection mechanisms. Comparisons of patients treated with HD-CT with historical control groups of patients treated with CD-CT may be misleading. A valid treatment comparison is only possible by means of large randomized trials. Clinicians should participate in the ongoing trials and enter all eligible patients.

North American Adjuvant Breast Cancer Trials

The National Cancer Institutes in the United States and Canada sponsor Cooperative Groups to perform randomized trials in distinct subsets of patients with early breast cancer. In women with low-risk ductal carcinoma in situ (DCIS), ongoing studies are evaluating the role of adjuvant breast irradiation. For those with low-risk, node-negative invasive tumors, efforts have been directed to improving the efficacy of tamoxifen, while in high-risk patients the focus has been on improving chemotherapy. The roles of dose intensity and dose density have been evaluated at dose levels requiring either G-CSF or stem cells. More recently, the introduction of taxanes into adjuvant regimens has been a major area of investigation. Following treatment with doxorubicin-cyclophosphamide (AC), patients have been randomized to receive paclitaxel or no further therapy in INT 0148 and NSABP B-28 and to receive docetaxel in NSABP B-27. For women with 4-9 involved nodes, sequential treatment A(doxorubicin)-T(paclitaxel)-C(cyclophosphamide) with G-CSF is being compared to AC x 4 followed by high-dose chemotherapy with stem cell support. Cooperative Group trials have been critical in defining the standard of care in the past, and successful completion of these new trials is essential for further progress against breast cancer.

High-Dose Chemotherapy in the Adjuvant Treatment of Breast Cancer: Benefit/Risk Analysis

BACKGROUND: High-dose chemotherapy (HDRx) may improve the prognosis of patients with high-risk breast cancer but at the expense of increased toxicity. However, no randomized, controlled trials have been published that clearly demonstrate the superiority of HDRx over conventional adjuvant chemotherapy. METHODS: We developed a simple model to compare benefits and risks of HDRx with conventional adjuvant chemotherapy (SDRx). The model integrates data on efficacy and risks of two competing treatment strategies into a single decision rule. RESULTS AND CONCLUSIONS: Using data from phase II studies, we show that if a disease-free survival is considered to be the most important outcome, HDRx should be administered when the probability of breast cancer relapse at five years exceeds 54% to 71% for patients with 4 to 9 positive nodes and exceeds 29% to 40% for patients with >9 positive nodes. If the endpoint of interest is five-year overall survival, then the treatment should be administered when the probability of relapse exceeds 77% to 83% for patients with 4 to 9 nodes involved and 22% to 31% for those with >9 lymph nodes involved. While awaiting results of randomized, controlled trials to definitively establish the efficacy rate of HDRx, we also found that HDRx could be considered in the management of high-risk breast cancer if its efficacy rate is at least 54% to 60% superior to SDRx in reducing relapse risk in breast cancer patients with 4 to 9 nodes and at least 31% to 38% for >9 positive nodes. If survival data are used instead of disease-free survival outcomes, HDRx efficacy should be at least 47% to 48% superior to SDRx in reducing death risk in breast cancer patients with 4 to 9 nodes and at least 27% to 30% superior for >9 positive nodes to consider its use in the adjuvant setting.