Considerations in using tumor markers: what the psycho-oncologist needs to know

Tumor markers are measures of biological features of a cancer. By revealing important biological aspects of the tumor, tumor markers can be useful in staging patients, predicting cancer outcomes, and guiding treatments. The psychological consequences of using tumor markers are virtually unknown. In this review article, we draw on clinical studies involving the psychological impact of risk information, screening, prognostic information and surveillance of cancer. Such studies may be helpful in considering possible psychological reactions to tumor marker information in clinical practice.

Circulating HER-2/erbB-2/c-neu (HER-2) extracellular domain as a prognostic factor in patients with metastatic breast cancer: Cancer and Leukemia Group B Study 8662

PURPOSE

The HER-2/erbB-2/c-neu (HER-2) proto-oncogene is a M(r) 185,000 transmembrane tyrosine kinase that is amplified and/or overexpressed by 20-40% of breast cancers. HER-2 has been associated with worse prognosis and resistance or sensitivity to specific treatment. We evaluated circulating levels of extracellular domain of HER-2 (ECD/HER-2) in metastatic breast cancer patients and investigated the prognostic and predictive significance of circulating HER-2 levels regarding endocrine therapy or chemotherapy.

EXPERIMENTAL DESIGN

Plasma samples from 242 patients were assayed for circulating ECD/HER-2 levels, using a sandwich enzyme immunoassay. ECD/HER-2 was correlated with clinical data gathered from these patients while they were participating in prospective Cancer and Leukemia Group B (CALGB) therapeutic protocols for metastatic breast cancer.

RESULTS

Eighty-nine (37%) of 242 patients had elevated ECD/HER-2 levels (> or =10.5 ng/ml). ECD/HER-2 was significantly associated with tumor burden, progesterone receptor levels, and presence of visceral metastases. Patients with elevated pretreatment levels had a significantly shorter OS but not time-to-progression than did those with ECD/HER-2 levels <10.5 ng/ml in univariate analysis. In univariate but not multivariate subset analyses, among patients treated with endocrine therapy (megestrol acetate), elevated initial ECD/HER-2 was associated with worse OS compared with nonelevated patients. However, among patients treated with chemotherapy (mainly anthracycline-containing regimens), OS did not differ significantly. Rates of response to either endocrine therapy or chemotherapy were similar for patients with elevated and nonelevated ECD/HER-2 levels.

CONCLUSIONS

ECD/HER-2 levels are elevated in 35-40% of patients with metastatic breast cancer. Elevated ECD/HER-2 levels are associated with a poorer prognosis in these patients. However, no predictive role for ECD/HER-2 was identified, either for endocrine therapy or for anthracycline-based chemotherapy in the metastatic setting.

Prognostic significance of plasma vascular endothelial growth factor levels in patients with hormone-refractory prostate cancer treated on Cancer and Leukemia Group B 9480

PURPOSE

Plasma vascular endothelial growth factor (VEGF) levels are significantly elevated in patients with hormone-refractory prostate cancer (HRPC) compared with patients with localized disease and have been associated with disease progression in other cancer patient populations. Therefore, we measured VEGF levels in plasma prospectively collected from patients enrolled in Cancer and Leukemia Group B 9480, an intergroup study of suramin in patients with HRPC, to determine whether these levels had prognostic significance.

EXPERIMENTAL DESIGN

Pretreatment plasma was collected from patients with HRPC enrolled in Cancer and Leukemia Group B 9480. In a subset of samples representative of the entire cohort, plasma VEGF levels were determined in duplicate using a Quantiglo chemiluminescent ELISA kit (R&D Systems, Minneapolis, MN). Statistical analyses were performed to determine the correlation between pretreatment plasma VEGF levels and time of overall survival. The proportional hazards model was used to assess the prognostic significance of various cut points in multivariate models.

RESULTS

Plasma VEGF levels in this population ranged from 4-885 pg/ml, with a median level of 83 pg/ml. As a continuous variable, plasma VEGF levels inversely correlated with survival time (P = 0.002). Using various exploratory cut points, plasma VEGF levels appeared to correlate with survival. In multivariate models in which other prognostic factors (serum prostate-specific antigen, alkaline phosphatase, evidence of measurable disease, and hemoglobin) were included, plasma VEGF levels were significant at various cut points tested.

CONCLUSION

Although these data are exploratory and need to be confirmed in an independent data set, they suggest that VEGF may have clinical significance in patients with HRPC.

Prognostic significance of reverse transcriptase polymerase chain reaction for prostate-specific antigen in men with hormone-refractory prostate cancer

PURPOSE

To evaluate the prognostic significance of reverse transcriptase polymerase chain reaction (RT-PCR) detection of prostate-specific antigen (PSA) mRNA in the blood of men with hormone-refractory prostate cancer (HRPC).

PATIENTS AND METHODS

Peripheral blood was obtained from 193 men enrolled on Cancer and Leukemia Group B Study 9480, a prospective randomized comparison of three doses of suramin. RNA was isolated from the samples and assayed for the presence of PSA transcripts by RT-PCR.

RESULTS

RNA could be isolated in 156 (83%) of samples. PSA transcripts as measured by RT-PCR were detectable in 75 (48%) of the 156 patients. The median survival for those patients in whom no transcripts were detectable was 18 months (95% confidence interval [CI], 14 to 22 months) compared with 13 months (95% CI, 11 to 15 months) (P =.004) for those in whom transcripts were detectable. In a multivariate analysis in which other factors predictive of survival were used, RT-PCR for PSA provided independent prognostic information.

CONCLUSION

RT-PCR for PSA predicts survival duration in a population of men with HRPC.

Phagocytosis of breast cancer cells mediated by anti-MUC-1 monoclonal antibody, DF3, and its bispecific antibody

Human epithelial mucin, MUC-1, is commonly expressed in adenocarcinoma including 80% of breast cancers. erbB-2 is overexpressed in approximately 30% of breast cancers. Expression of MUC-1 and erbB-2 may be partially overlapping but discoordinate. Therefore, combined use of antibodies directed against these two antigens might increase the number of patients who benefit from immunotherapy. Monoclonal antibody (MAb) DF3 recognizes the MUC-1 tandem repeat. We investigated phagocytosis and cytolysis of cultured human breast cancer cells by monocyte-derived macrophages mediated by MAb DF3 and its bispecific antibody (BsAb) DF3xH22 with the second epitope directed against the Fc component of phagocytic cells. Purified monocytes from healthy donors were cultured with granulocyte macrophage colony-stimulating factor with or without IFN-gamma. antibody-dependent cellular phagocytosis (ADCP) and antibody-dependent cellular cytotoxicity (ADCC) assays were performed with these macrophages and MUC-1-expressing target cells (ZR75-1) in the presence of MAb DF3 and BsAb DF3xH22. ADCP was measured by two-color fluorescence flow cytometry using PKH2 (green fluorescent dye) and R-phytoerythrin (RPE) (red)-conjugated MAb against human CD14 and CD11b and was confirmed by confocal microscopy. ADCC was measured by (51)Cr release assay. Immunohistochemical staining studies of MUC-1 and erbB-2 were performed on 67 primary breast cancer tissues. Expression of MUC-1 and erbB-2 was partially overlapping but discoordinate in 67 consecutive breast cancers. Both MAb DF3 and BsAb DF3xH22 mediated ADCP. However, ADCP mediated by MAb DF3 was greater than that mediated by BsAb DF3xH22. ADCC as detected by (51)Cr release was not seen with either antibody. The addition of IFN-gamma to monocyte-derived macrophage cultures inhibited ADCP compared to granulocyte macrophage colony-stimulating factor alone. Given the partially overlapping but discoordinate expression of MUC-1 and erbB-2 in breast cancer, therapy directed toward both antigens should be considered. MAb DF3 and the BsAb DF3xH22, can effectively mediate phagocytosis of MUC-1-expressing target cells. Further investigations are needed to determine whether this antibody-induced phagocytosis results in long-term specific T-cell activation against MUC-1.

When is a tumor marker ready for prime time? A case study of c-erbB-2 as a predictive factor in breast cancer

PURPOSE

c-erbB-2 (HER-2, c-neu) might play a role as a predictive factor in breast cancer. However, the clinical utility of the marker in this disease is still not established. We conducted a critical analysis of the literature, in which we reviewed the factors that contribute to the lack of acceptance of c-erbB-2 for clinical use and attempted to determine the predictive role of c-erbB-2 for response to specific therapies.

METHODS

We conducted a MEDLINE literature search using the keywords c-erbB-2, HER2, neu, and breast cancer, reviewed the references included in each publication, and reviewed abstracts that have been reported in the 1997-2000 proceedings to the American Association of Cancer Research and American Society for Clinical Oncology annual meetings.

RESULTS

The preclinical and clinical data reported to date suggest that amplification or overexpression of c-erbB-2 is a weak to moderate negative pure prognostic factor. c-erbB-2 seems to be a weak to moderate negative predictive factor for response to endocrine therapy. The marker is also a moderate negative predictive factor for response to alkylating agents and a moderate positive predictive factor for response to anthracyclines. The data regarding response to taxanes or radiotherapy are not sufficient to make recommendations regarding treatment decision making. Finally, c-erbB-2 is a strong predictive factor for response to trastuzumab.

CONCLUSION

We conclude that, in the adjuvant setting, c-erbB-2 status should not be used to determine whether a woman should receive adjuvant systemic therapy (weak prognostic factor). In addition, c-erbB-2 status should not be used to determine whether a patient should receive endocrine therapy. When adjuvant chemotherapy is recommended, anthracycline-based therapy should be the preferred regimen for c-erbB-2-positive patients. However, when anthracyclines are contraindicated, alkylating agent-based therapy should not be withheld. To determine the true predictive role and strength of the marker for response to each therapy, prospective randomized clinical trials or formal meta-analyses are required.

Vascular endothelial growth factor and basic fibroblast growth factor urine levels as predictors of outcome in hormone-refractory prostate cancer patients: a cancer and leukemia group B study

Better prognostic markers are needed for hormone-refractory prostate cancer (HRPC) patients. No single biochemical or clinical parameter can reliably predict patient response to therapy or rapidity of disease progression. Peptide factors involved in major cancer growth pathways, such as tumor angiogenesis, are attractive candidates as markers of low- and high-risk HRPC patients. We analyzed prospectively collected urine specimens from 100 of 390 HRPC patients undergoing therapy with the growth factor antagonist suramin as part of CALGB 9480. Levels of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) were assessed from day 1 of therapy (D1) and day 29 (D29) urine samples from this subset of 100 randomly selected patients. Growth factor levels were determined by standardized ELISA microtiter plate assays from a commercial (bFGF) or proprietary (VEGF) source. Pretreatment urine VEGF levels were predictive of survival. In univariate analysis, patients whose baseline urine VEGF level was < or =28 pg/ml (the median level) had an average survival of 17 months; those with baseline VEGF >28 pg/ml had a significantly shorter survival of 10 months (P = 0.024). This difference corresponded to a 60% increased risk of dying for the higher urine VEGF patients (hazard ratio, 1.62; P = 0.03) and remained significant in multivariate analysis (hazard ratio, 1.72, P = 0.02). No significant correlations between urine bFGF level or change in bFGF levels and survival were found. These results support the notion that certain peptide growth factor-mediated, mitogenic pathways are important in HRPC and that their levels can predict outcome.

2000 update of recommendations for the use of tumor markers in breast and colorectal cancer: clinical practice guidelines of the American Society of Clinical Oncology

OBJECTIVE

To update the 1997 clinical practice guidelines for the use of tumor marker tests in the prevention, screening, treatment, and surveillance of breast and colorectal cancers. These guidelines are intended for use in the care of patients outside of clinical trials.

OPTIONS

Six tumor markers for colorectal cancer and eight for breast cancer were considered. They could be recommended or not for routine use or for special circumstances. In addition to carcinoembryonic antigen (CEA) and CA 15-3, CA 27.29 was also considered among the serum tumor markers for breast cancer.

OUTCOMES

In general, the significant health outcomes identified for use in making clinical practice guidelines (overall survival, disease-free survival, quality of life, lesser toxicity, and cost-effectiveness) were used.

EVIDENCE

A computerized literature search from 1994 to March 1999 was performed.

VALUES

The same values for use, utility, and levels of evidence were used by the committee.

BENEFITS, HARMS, AND COSTS

The same benefit, harms, and costs were used.

RECOMMENDATION

Changes were recommended (see Appendix).

VALIDATION

The updated recommendations were validated by external review by the American Society of Clinical Oncology's (ASCO's) Health Services Research Committee and by ASCO's Board of Directors.

SPONSOR

American Society of Clinical Oncology.

New prognostic factors for breast cancer recurrence

Decisions regarding the use of adjuvant therapy for breast cancer are strongly influenced by the risk of disease recurrence and death. These risks are now determined by examining the currently recognized breast cancer prognostic factors including clinical stage, axillary nodal status, tumor size and grade, hormone receptor status, and presence of lymphovascular involvement. Newer factors are being evaluated in an attempt to more precisely define disease-related prognosis. This article provides an overview of issues that need to be considered when analyzing studies of prognostic factors, as well as a review of the currently recognized and the newer candidate prognostic factors.

Phase II evaluation of thalidomide in patients with metastatic breast cancer

PURPOSE

To determine the efficacy, safety, pharmacokinetics, and effect on serum angiogenic growth factors of two dose levels of thalidomide in patients with metastatic breast cancer.

PATIENTS AND METHODS

Twenty-eight patients with progressive metastatic breast cancer were randomized to receive either daily 200 mg of thalidomide or 800 mg to be escalated to 1,200 mg. Fourteen heavily pretreated patients were assigned to each dose level. Each cycle consisted of 8 weeks of treatment. Pharmacokinetics and growth factor serum levels were evaluated.

RESULTS

No patient had a true partial or complete response. On the 800-mg arm, 13 patients had progressive disease at or before 8 weeks of treatment and one refused to continue treatment. The dose was reduced because of somnolence to 600 mg for five patients and to 400 mg for two and was increased for one to 1,000 mg and for four to 1,200 mg. On the 200-mg arm, 12 patients had progressive disease at or before 8 weeks and two had stable disease at 8 weeks, of whom one was removed from study at week 11 because of grade 3 neuropathy and the other had progressive disease at week 16. Dose-limiting toxicities included somnolence and neuropathy. Adverse events that did not require dose or schedule modifications included constipation, fatigue, dry mouth, dizziness, nausea, anorexia, arrhythmia, headaches, skin rash, hypotension, and neutropenia. Evaluation of circulating angiogenic factors and pharmacokinetic studies failed to provide insight into the reason for the lack of efficacy.

CONCLUSION

Single-agent thalidomide has little or no activity in patients with heavily pretreated breast cancer. Further studies that include different patient populations and/or combinations with other agents might be performed at the lower dose levels.

Prognostic factors in breast cancer. College of American Pathologists Consensus Statement 1999

BACKGROUND

Under the auspices of the College of American Pathologists, a multidisciplinary group of clinicians, pathologists, and statisticians considered prognostic and predictive factors in breast cancer and stratified them into categories reflecting the strength of published evidence.

MATERIALS AND METHODS

Factors were ranked according to previously established College of American Pathologists categorical rankings: category I, factors proven to be of prognostic import and useful in clinical patient management; category II, factors that had been extensively studied biologically and clinically, but whose import remains to be validated in statistically robust studies; and category III, all other factors not sufficiently studied to demonstrate their prognostic value. Factors in categories I and II were considered with respect to variations in methods of analysis, interpretation of findings, reporting of data, and statistical evaluation. For each factor, detailed recommendations for improvement were made. Recommendations were based on the following aims: (1) increasing uniformity and completeness of pathologic evaluation of tumor specimens, (2) enhancing the quality of data collected about existing prognostic factors, and (3) improving patient care.

RESULTS AND CONCLUSIONS

Factors ranked in category I included TNM staging information, histologic grade, histologic type, mitotic figure counts, and hormone receptor status. Category II factors included c-erbB-2 (Her2-neu), proliferation markers, lymphatic and vascular channel invasion, and p53. Factors in category III included DNA ploidy analysis, microvessel density, epidermal growth factor receptor, transforming growth factor-alpha, bcl-2, pS2, and cathepsin D. This report constitutes a detailed outline of the findings and recommendations of the consensus conference group, organized according to structural guidelines as defined.

Association of angiogenesis in lymph node metastases with outcome of breast cancer

BACKGROUND

Microvessel density (MVD) is a measure of the extent of new blood vessel growth or angiogenesis, which is required for tumor progression. Increased MVD in primary breast cancers appears to adversely affect disease-free survival and overall survival in patients with breast cancer. However, the clinical implications of angiogenesis in breast cancer metastases have not been well studied. The purpose of this study was to compare intratumoral MVD in primary breast cancer tissues with MVD in axillary lymph node metastases and to evaluate the relationships among primary- and metastatic-tumor MVD, disease-free survival, and overall survival in patients with lymph node-positive, stage II breast cancer who were treated with adjuvant chemotherapy in Cancer and Leukemia Group B Protocol 8082.

METHODS

Immunostaining for factor VIII-related antigen was performed on tissue sections from 47 primary tumors and 91 axillary lymph nodes containing metastases from 110 patients with lymph node-positive breast cancer. Sections were examined for the presence or absence of focal areas of relatively intense neovascularization (vascular hot spots), and a quantitative assessment of intratumoral MVD was performed.

RESULTS

The presence of vascular hot spots in axillary lymph node metastases, but not primary breast cancers, was associated with statistically significantly decreased disease-free survival (P =.006) and overall survival (P =.004) by univariate analysis. Similarly, increased MVD in metastases, but not in primary tumors, was statistically significantly associated with diminished overall survival in these patients (P =.02). In multivariate analysis, the number of positive axillary lymph nodes and the presence of vascular hot spots in axillary lymph node metastases predicted decreased disease-free survival (P =.0001 and.02, respectively) and overall survival (P =.0001 and.007, respectively). All P values were two-sided.

CONCLUSION

This pilot study suggests that assessing neovascularization in axillary lymph node metastases may provide clinically useful information regarding survival in patients with primary breast cancer.

A pilot trial assessing the efficacy of paroxetine hydrochloride (Paxil) in controlling hot flashes in breast cancer survivors

BACKGROUND

Many breast cancer survivors suffer debilitating hot flashes. Estrogen, the drug of choice in perimenopausal women, is generally not recommenced to breast cancer survivors. Nonhormonal treatments are mostly disappointing. Anecdotal reports in our institution suggested that the selective serotonin-reuptake inhibitor, paroxetine hydrochloride, might be efficacious in alleviating hot flashes.

PATIENTS AND METHODS

Thirty women with prior breast cancer who were suffering at least two hot flashes a day entered a single institution pilot trial to evaluate paroxetine's efficacy in reducing the frequency and severity of hot flashes. After completing daily diaries for one week on no therapy, the women received open-label paroxetine, 10 mg daily for one week, followed by four weeks of paroxetine, 20 mg daily. The women completed hot-flash daily diaries throughout the study period, and a health-related symptom-assessment questionnaire and a quality-of-life rating scale in the first and sixth week of the study.

RESULTS

Twenty-seven women completed the six-week study period. The mean reduction of hot flash frequency was 67% (95% confidence interval (95% CI): 56%-79%). The mean reduction in hot flash severity score was 75% (95% CI: 66%-85%). There was a statistically significant improvement in depression, sleep, anxiety, and quality of life scores. Furthermore, 25 (83%) of the study participants chose to continue paroxetine therapy at the end of study. The most common adverse effect was somnolence, resulting in drug discontinuation in two women, and dose reduction in two women. One woman discontinued drug due to anxiety.

CONCLUSIONS

Paroxetine hydrochloride is a promising new treatment for hot flashes in breast cancer survivors, and warrants further evaluation in a double-blind randomized placebo-controlled trial.

Treatment-related toxicity from a randomized trial of the sequencing of doxorubicin and radiation therapy in patients treated for early stage breast cancer

PURPOSE

There is concern that breast cancer patients treated with left-sided radiation therapy (XRT) and doxorubicin (DOX) may have an increased risk of cardiac toxicity. In addition, the effect of different sequencing of XRT and chemotherapy (CT) on the likelihood of cardiotoxicity, as well as cellulitis, arm edema, or brachial plexopathy, is not well understood. We reviewed the records of patients treated on a randomized trial testing the sequencing of CT and XRT to determine if there was an increase in cardiac events or other complications in patients treated with a total dose of DOX of 180 mg/m2 and XRT, comparing patients with treatment to the left breast and the right breast, and comparing patients treated with initial CT and initial RT.

MATERIALS AND METHODS

From June 1984 to December 1992, 244 patients with clinical stage I or II breast cancer were randomized following conservative surgery to receive CT (4 cycles of CAMFP at 3 week intervals) either before or after XRT (45 Gy to the entire breast, followed by a boost of 16 Gy; nodal radiation therapy was optional). Two hundred thirty-one patients were evaluable for the development of cardiac toxicity. The median age at diagnosis was 45 years (range, 20-68). CT doses were: doxorubicin, 45 mg/m2 IV bolus, d 3; methotrexate, 200 mg/m2 IV, d 1 and 15; 5-fluorouracil, 500 mg/m2 IV, d 1; cyclophosphamide, 500 mg/m2 IV, d 1; prednisone 40 mg p.o., d 1-5. A cardiac event was defined as a myocardial infarction or clinical evidence of congestive heart failure. Median follow-up time was 53 months.

RESULTS

No cardiac events were observed for patients with either left- or right-sided breast cancer. The sequencing of CT and XRT had no significant effect on the risk of cardiac toxicity, cellulitis, arm edema or brachial plexopathy.

CONCLUSIONS

We observed no evidence of an increased risk of cardiac toxicity from the addition of left breast tangential irradiation to DOX at a total dose of 180 mg/m2. Additional follow-up is needed to exclude possible late events. In addition, the sequencing of CT and XRT does not appear to affect the risk of cellulitis, arm edema, or brachial plexopathy.

Meta-analysis of trials comparing toremifene with tamoxifen and factors predicting outcome of antiestrogen therapy in postmenopausal women with breast cancer

Meta-analysis of all clinical data was conducted to compare toremifene 40-60 mg/day (TOR) with tamoxifen 20-40 mg/day (TAM) in postmenopausal women with estrogen receptor (ER) positive or ER unknown advanced breast cancer and assess factors predicting treatment outcome. Data from five randomized parallel group studies (all studies) were combined. Efficacy variables were the response rate in all studies and also the time to treatment failure and survival in the three major studies (pivotal studies). Of the 1421 patients, 725 received TOR and 696 TAM. Response rates were 24.0% and 25.3%, respectively (p = 0.675) with 95% confidence interval (95% CI) for the difference -5.3 to 3.4. Of the 1157 patients in the pivotal studies, 75% had progressed and 50% expired. Median treatment times were 4.9 months in TOR and 5.3 months in TAM groups (p = 0.762, hazard ratio 0.98 with 95% CI 0.87-1.11). Median survival times were 31.0 (TOR) and 33.1 (TAM) months (p = 0.758, hazard ratio 0.98 with 95% CI 0.83-1.15). All results are consistent with the criteria of statistical equivalence between TOR and TAM. More patients in TAM (20%) than in TOR (14%, p = 0.007) discontinued the treatment prematurely but overall the treatments were well tolerated. As the treatments were equally effective all data were analyzed together for predictive factors. High tumor ER concentration, long disease free time, soft tissue metastases, few metastatic sites, and good performance status all independently predicted longer survival (p<0.001). Previous adjuvant tamoxifen predicted shorter survival (p = 0.008). Objective response to treatment or disease stabilization for at least 12 months both predicted prolonged survival (p = 0.001). TOR 60 mg/day and TAM are equally effective and well tolerated in the treatment of advanced breast cancer in postmenopausal women. Probability of survival may be predicted based on patient characteristics and on the initial response to the treatment.

Phase II trial of high-dose liposome-encapsulated doxorubicin with granulocyte colony-stimulating factor in metastatic breast cancer. TLC D-99 Study Group

PURPOSE

To estimate the toxicity and response rate of high-dose liposome-encapsulated doxorubicin (TLC D-99, Evacet, The Liposome Company Inc, Princeton, NJ) in patients with advanced breast cancer.

PATIENTS AND METHODS

Fifty-two breast cancer patients with bidimensionally measurable metastatic disease and no prior chemotherapy for metastatic disease received a 135 mg/m2 intravenous (i.v.) bolus of TLC D-99 with 5 microg/kg of granulocyte colony-stimulating factor via subcutaneous injection every 21 days.

RESULTS

The median number of treatment cycles of TLC D-99 was three (range, one to 10 cycles), and the median total cumulative dose of TLC D-99 was 405 mg/m2 (range, 135 to 1,065 mg/m2). Grade IV neutropenia, thrombocytopenia, and mucositis were experienced by 48 (92%), 46 (88%), and 10 (19%) patients, respectively. Twenty (38%) of patients experienced cardiac toxicity: four (8%) experienced a decrease of 20% or more in left ventricular ejection fraction (LVEF) to a final value > or = 50%, nine (17%) experienced a decrease of 10% or more in LVEF to a final value less than 50%, and seven (13%) developed symptomatic congestive heart failure (CHF), including one patient who died of cardiomyopathy after receiving a total dose of 1,035 mg/m2. In a stepwise logistic regression model, the significant risk factors for the development of CHF were the cumulative dose of prior adjuvant doxorubicin (P = .007) and the total cumulative dose of TLC D-99 (P = .032). The overall response rate was 46% (95% confidence interval [CI], 32% to 61%) on an intent-to-treat basis. The median duration of response was 7.4 months (95% CI, 6.1 to 19.6 months) and the median progression-free survival was 6.1 months (95% CI, 5.4 to 7.5 months).

CONCLUSION

There was no added therapeutic benefit to the dose escalation of TLC D-99 in this study. A high rate of cardiotoxicity was also observed, especially among patients who had received prior adjuvant doxorubicin. This was probably attributable to the dose and schedule of TLC D-99 used in this trial, as well as the patient's lifetime cumulative doxorubicin dose. Administration of high-dose TLC D-99 at 135 mg/m2 every 3 weeks by i.v. bolus infusion does not warrant further investigation.

Assessing the clinical impact of prognostic factors: when is "statistically significant" clinically useful?

Very few tumor markers have been recommended for routine clinical care of patients with breast cancer. A framework to determine the clinical utility of tumor markers is required. In a previous publication, a "Tumor Marker Utility Grading System" (TMUGS) was proposed. TMUGS included a semi-quantitative grading scale (0-3+) which can be used to assign a score to a given tumor marker for a given outcome. Only those markers that are felt to be sufficiently strong to influence a therapeutic decision that results in improved clinical outcome for the patient are recommended. The studies from which data are used to assign a TMUGS grade can be placed into one of five Levels of Evidence (LOE). An extension of TMUGS ("TMUGS-Plus") is now proposed in which the relative strength of a prognostic or predictive factor can be estimated and expressed in terms of a risk ratio (RR) for prognostic factors or benefit ratio (BR) for predictive factors. Three categories of prognostic factors and three categories of predictive factors are proposed (strong, moderate, and weak). It is recommended that only LOE type I studies (prospective, highly powered studies of the tumor marker, or meta-analysis of LOE II or III datasets), be used to estimate the RR or BR of a given factor. Finally, a matrix, based on assumptions of acceptable absolute benefits relative to risks, is proposed in which any given tumor marker can be assessed for its clinical utility. TMUGS-Plus should aid in the assessment of published data regarding clinical utility of tumor markers. Perhaps more important, clinical investigators can use TMUGS-Plus to design tumor marker studies that will fulfill criteria for clinical utility, resulting in more rapid acceptance of tumor markers for routine clinical use.

Circulating tumor markers in breast cancer: accepted utilities and novel prospects

Detecting and/or monitoring changes in circulating tumor markers might assist in evaluating cancer risk, diagnosis, prognosis, or response to treatment. Several categories of circulating tumor markers have been investigated in breast cancer. These categories include classical tumor-associated antigens, such as CEA and CA 15-3, markers of tumor biology, including markers of angiogenesis, adhesion, and invasion, and antibody response to tumor-associated antigens such as HER2/neu and p53. We used a recently proposed Tumor Marker Utility Grading System to evaluate the use of several circulating tumor markers for different clinical utilities in breast cancer. While there are no tumor markers with established clinical utilities for most uses, tumor-associated antigens can be used for monitoring patients with metastatic disease. In addition, markers of tumor biology such as the circulating extracellular domain of HER2/neu might be useful in determining not only prognosis, but also response to specific treatments. However, further investigations are required to further assess the utility of individual tumor markers for specific clinical uses.

Antibody dependent cellular phagocytosis (ADCP) and antibody dependent cellular cytotoxicity (ADCC) of breast cancer cells mediated by bispecific antibody, MDX-210

BACKGROUND

MDX-210 is a bispecific antibody (BsAb) with specificity for both the proto-oncogene product of HER-2/neu (c-erbB-2) and FcgammaRI (CD64). HER-2/neu is overexpressed in malignant tissue of approximately 30% of patients with breast cancer, and FcgammaRI is expressed on human monocytes, macrophages, and IFN-gamma activated granulocytes. We investigated phagocytosis and cytolysis of cultured human breast cancer cells by human monocyte-derived macrophages (MDM) mediated by BsAb MDX-210, its partially humanized derivative (MDX-H210), and its parent MoAb 520C9 (anti-HER-2/neu) under various conditions.

MATERIALS AND METHODS

Purified monocytes were cultured with GM-CSF, M-CSF, or no cytokine for five or six days. Antibody dependent cellular phagocytosis (ADCP) and cytolysis (ADCC) assays were performed with the MDM and HER-2/neu positive target cells (SK-BR-3). ADCP was measured by two-color fluorescence flow cytometry using PKH2 (green fluorescent dye) and phycoerythrin-conjugated (red) monoclonal antibodies (MoAb) against human CD14 and CD11b. ADCC was measured with a non-radioactive LDH detection kit.

RESULTS

Both BsAb MDX-210 (via FcgammaRI) and MoAb 520C9 (mouse IgG1, via FcgammaRII) mediated similar levels of ADCP and ADCC. ADCP mediated by BsAb MDX-H210 was identical to that mediated by BsAb MDX-210. Confocal microscopy demonstrated that dual-labeled cells represented true phagocytosis. Both ADCP and ADCC were higher when MDM were pre-incubated with GM-CSF than when incubated with M-CSF.

CONCLUSIONS

BsAb MDX-210 is as active in vitro as the parent MoAb 520C9 in inducing both phagocytosis and cytolysis of MDM. MDX-210 and its partially humanized derivative, MDX-H210, mediated similar levels of ADCP. GM-CSF appears to superior to M-CSF in inducing MDM-mediated ADCC and ADCP. These studies support the ongoing clinical investigations of BsAb MDX-210 and its partially humanized derivative.