Creating Models to Identify New Therapeutic Options for Aggressive African Breast Cancers

Background: Population-based incidence rates of breast cancer (BC) that does not express the estrogen receptor (ER), progesterone receptor (PR) or overexpress the human epidermal growth factor 2 HER2/ neu (triple negative breast cancer, TNBC) are higher among Africans compared with white women. However the underlying biologic and genetic differences among different ethnicities are poorly understood and there are currently very few ethnically diverse BC models available for identifying new therapeutic options. Aim: Establish an international collaboration to: i, characterize African breast tumors ii, create models for studying these tumors and iii, identify biomarkers for early detection and treatment personalization. Methods: We have collected tumors from 154 white Americans WA, 76 African Americans, AA, 190 Ethiopians, Eth, and 286 Ghanaian (Gh) BC patients. We then established a unique resource of patient derived xenografts (PDX) from these tumors. The PDXs were then fully characterized using whole exome and RNA sequencing for the primary tumor, matched normal DNA, and corresponding low passage PDXs. Using immunohistochemistry, we evaluated the ER, PR, HER2/ neu, androgen receptor (AR), and ALDH1 (cancer stem cell marker) expression among these tumors. Based on biomarker expression the PDXs were then tested against a panel of IND drugs, either alone or in combinations, in an ex vivo organoid culture system to discover potential new therapeutic options. Results: Mean age at BC diagnosis was 43; 49; 60; and 57 years for the Eth; Gh; AA; and WA patients, respectively. The proportion of TNBC was significantly higher for the AA and Gh patients (41% and 54%, respectively) compared with the WA and Eth patients (23% and 15%, respectively); P < 0.001. Significant differences were observed for distribution of AR positivity, which was 71%; 55%; 42% and 50% for the WA; AA; Gh; and Eth cases, respectively ( P = 0.008). The Gh breast tumors exhibited the highest number of loss of function and missense mutations that are likely to impact therapy with a high frequency of P53, APC, and FGFR mutations. These mutations were maintained in the corresponding PDXs that were developed, and were thus used as biomarkers for drug screening. These tumors exhibited a gene expression signature based on the ethnicity of the patients with 2385 genes differentially expressed between Gh and AA, 1573 between AA and CA and 1317 between GH and CA. Results from our ongoing drug screening and biomarker identification will be available soon. Conclusions: Establishing the molecular and genetic platform of aggressive breast cancers occurring in women with African ancestry will help in identifying biomarkers for early cancer detection and targeted treatment stratification for optimum patient outcome. The availability of tumor models based on tumors from diverse African populations is the important missing pieces that have to be incorporated into current drug discovery efforts.

Abstract P6-07-01: Withdrawn

This abstract was withdrawn by the authors.

Abstract P2-09-26: Frequency and mechanisms of elevated somatic mutation burden in metastatic breast cancer and response to immune checkpoint blockade

Background: Immune checkpoint blockade (ICB) is effective in the treatment of various malignancies. Thus far, however, results in breast cancer have been mixed. Elevated tumor mutational load, and subsequent increased likelihood of forming immunogenic neoantigens, has been correlated with response to ICB. Mutational load observed in breast cancers varies widely. However, most studies have assessed mutational load using primary tumors. Few studies have explored the frequency of high mutational load, molecular mechanisms accounting for this phenomenon, and its potential impact on response to ICB in metastatic breast cancer (MBC).

Methods: From 2011-2016, 124 patients (pts) with MBC of varying subtypes underwent research biopsy of their metastatic disease for whole genome, exome and transcriptome sequencing of tumor and matched normal sample through the Michigan Oncology Sequencing Center (Mi-OncoSeq). Those pts with elevated somatic mutation load were defined as having greater than 10 mutations per megabase of targeted sequencing and mutational signatures accounting for high mutation load were noted. Pts treated subsequently with ICB were followed to assess response.

Results: Twelve MBC pts had high mutation load (10% of cohort). Eight pts had estrogen receptor (ER) positive MBC and 4 pts had metastatic triple negative breast cancer (TNBC). In 5 cases, a clear mutational signature accounting for high mutation load was evident. Two TNBC cases harbored an APOBEC mutational signature in addition to 1 TNBC and 2 ER positive tumors displaying a microsatellite instability signature (MSI-H). Among the tumors with MSI-H signature, 1 case was associated with a pathogenic germline alteration in MLH1. Two pts were subsequently treated with ICB on a clinical trial. One pt came off study after 3 months due to progressive brain metastases and another had partial response to therapy lasting 7 months.

Conclusions: Elevated somatic mutation burden in MBC is observed in approximately 10% of pts, and is detected in both ER positive and TNBC. Since high mutation burden has been associated with increased likelihood of response to ICB, identification of this genomic feature could have important therapeutic implications for MBC pts.

Citation Format: Cobain EF, Robinson DR, Wu Y-M, Lonigro R, Vats P, Rabban E, Kumar-Sinha C, Schott AF, Smerage JB, Morikawa A, Burness ML, Van Poznak CH, Griggs J, Wicha M, Hayes DF, Chinnaiyan AM. Frequency and mechanisms of elevated somatic mutation burden in metastatic breast cancer and response to immune checkpoint blockade [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-09-26.

Abstract P6-12-14: Comparative analysis of breast cancer phenotypes in African American, White American, and African patients- Correlation between African ancestry and triple negative breast cancer

Introduction: Population-based incidence rates of triple negative breast cancer (TNBC) are higher for African American (AA) compared to White American (WA) women, but it is unclear whether TNBC risk is genetically associated with African ancestry because AA women represent an ancestrally admixed population. Higher frequencies of TNBC have also been observed in sub-Saharan African breast cancer (BC) patients, but comparative analyses of biomarker expression among datasets that include AA, WA, and African women are sparse. We report findings from an international registry that features specimens from a diverse patient population in Detroit, Michigan as well as a hospital in Kumasi, Ghana.

Methods: The study dataset included formalin-fixed, paraffin-embedded invasive BC tumors diagnosed between 1998 and 2014 at the Komfo Anokye Teaching Hospital in Ghana and the prospectively-maintained/annotated Henry Ford Health System cohort in Michigan. All Ghanaian tumors underwent pathology confirmation and immunohistochemistry for estrogen receptor (ER), progesterone receptor (PR) and HER2/neu expression at the University of Michigan. Women were classified into five BC phenotypes and dichotomized into two age groups, &lt;50 and ≥50 years. Polychotomous multivariate GLM models were developed to estimate the risk for each BC phenotype. Statistical analyses were performed in SAS v. 9.0 (Carey, NC). This research was approved by the Institutional Review Boards of the participating institutions.

Results: A total of 234 Ghanaian cases with mean age 49 years (range 24-92); 271 AA with mean age 60 (range 27-87); and 321 WA with mean age 62 (range 31-91) (P=0.001) contributed to this study. Prevalence of histologic grade 3 was lowest in WA (n=107, 33.7%) which was statistically significant from the observed prevalence in AA (n=135, 50.4%) and Ghanaians (n=84, 53.8%) (P&lt;0.0001). ER-negative and TNBC were more common among Ghanaian and AA compared to WA cases (frequency ER-negativity 67.5%, 37.1%, and 19.8%, respectively, p&lt;0.0001; frequency TNBC 53.2%, 29.8%, and 15.5%, respectively, p&lt;0.0001). In the age group &lt;50 years, 82 women (42.5%) were diagnosed with ER+/PR+/HER2-, 65 (33.7%) with TNBC, 27 (14.0%) with ER+/PR+/HER2+, 14 (7.2%) with ER-/PR-/HER2+ and 5(2.6%) with ER-/PR+/HER2- phenotypes. In this young age group, prevalence of TNBC remained highest among Ghanaian women (50.8%), followed by AA (34.3%) and WA (15.9%); (P=.0006). In contrast, highest prevalence of ER+/PR+/HER2+ and ER+/PR+/HER2- phenotypes was observed in WA, followed by AA and Ghanaians. On multivariate analysis histologic grade 3 and racial heritage remained statistically significantly associated with the TNBC phenotype (OR for AA vs. WA with TNBC 1.87, 95% CI 1.15-3.04; OR for Ghanaian vs. WA with TNBC 10.63, 95% CI 5.32-21.25; OR for Grade 3 vs Grade 1 histology with TNBC 33.3, 95% CI 13.45-82.4).

Conclusions: This study confirms an association between the TNBC phenotype and African ancestry; furthermore, extent of African ancestry appears to be associated with an increased likelihood of having a TNBC tumor, since frequency of TNBC among AA patients was intermediate between WA and Ghanaian patients.

Citation Format: Newman LA, Jiagge E, Bensenhaver JM, Chitale D, Kleer C, Merajver S, Kyei I, Aitpillah F, Oppong J, Amankwaa-Frempong E, Adjei E, Wicha M, Awuah B, Stark A. Comparative analysis of breast cancer phenotypes in African American, White American, and African patients- Correlation between African ancestry and triple negative breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-12-14.

Abstract PD08-06: Duloxetine for Treatment of Aromatase Inhibitor (AI)-Associated Musculoskeletal Syndrome (AIMSS)

Background: Approximately 50% of postmenopausal women with hormone receptor positive early stage breast cancer treated with an aromatase inhibitor (AI) develop arthralgias. Standard analgesics are relatively ineffective. Duloxetine is a serotonin and norepinephrine receptor inhibitor with proven efficacy for treatment of multiple chronic pain states. We investigated the hypothesis that duloxetine would be efficacious for treatment of AIMSS.

Methods: We performed a single-arm, open-label phase II study of duloxetine in 35 postmenopausal women who had been treated with AI therapy for at least 2 weeks and who developed new or worsening pain after starting AI therapy that was rated at least 4 on a 10 point Visual Analog Scale. Enrollment was completed in June 2010. Subjects were treated with duloxetine 30 mg daily for one week, and then 60 mg daily for 3 weeks. Depending on patient-perceived response to therapy, patients had the option of continuing duloxetine 60 mg daily or increasing the dose to 60 mg twice daily for the subsequent 4 weeks. Change in patient-reported pain was assessed. Outcome measures included the Brief Pain Inventory (BPI) and modified Health Assessment Questionnaire (HAQ). Benefit from therapy was defined as a 30% decrease in average pain score from baseline to 8 weeks. Paired t tests were used for statistical analysis.

Results: Of the 35 enrolled subjects, 20 subjects completed the 8-week study period, 6 subjects discontinued therapy early because of duloxetine-associated toxicity, and 9 subjects had been enrolled less than 8 weeks at the time of this analysis and were therefore not evaluable. In an intent-to-treat analysis, 16 of 26 evaluable subjects (61.5%) experienced at least a 30% decrease in average pain, and 14 of 20 subjects (70%) who completed all 8 weeks of protocol-directed treatment chose to continue duloxetine therapy. There were statistically significant reductions in average pain severity (p &lt; 0.0001) and maximum pain severity (p &lt; 0.0001) from baseline to 8 weeks. The mean percent reduction in average pain severity between baseline and 8 weeks was 56.1% (95% CI 37.9%-74.2%) and in maximum pain severity was 55.7% (95% CI 37.3%-74.1%). No grade 3 or 4 adverse events were reported. The most common adverse events were fatigue and drowsiness, xerostomia, nausea, and headache.

Conclusions: Duloxetine appears to be effective and well-tolerated for treatment of AIMSS. Final results from the entire cohort will be presented. Future randomized, placebo-controlled studies are warranted. Clinicaltrials. gov NCT01028352.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr PD08-06.

Abstract P6-15-03: Phase Ib Trial of the Gamma Secretase Inhibitor (GSI), MK-0752 Followed by Docetaxel in Locally Advanced or Metastatic Breast Cancer

Background: The cancer stem cell hypothesis asserts that there is a small population of cells within a tumor that has the ability to self renew and differentiate, and that these cells drive tumor growth and metastasis but are resistant to conventional cytotoxic chemotherapy. Pathways involved in stem cell growth and differentiation are viable targets for new anticancer therapies. One such pathway, Notch, is inhibited by GSIs which prevent translocation of Notch intracellular domain to the nucleus. Inhibition of GS concurrent with chemotherapy might improve disease control by targeting both stem cells and differentiated cells within the tumor. This Phase Ib clinical trial was designed to determine the MTD of the GSI, MK-0752, in combination with docetaxel, and to evaluate an effect on stem cell markers in serial tumor biopsies.

Methods: Eligible subjects had metastatic breast cancer or locally advanced breast cancer that did not respond to anthracycline therapy. Patients with disease that progressed on a taxane, or who had received a taxane within 6 months were excluded. MK-0752 was administered orally on days 1-3 of each 21-day cycle of therapy, in escalating doses. Dose levels (mg/day) 1=300; 2=450; 3=600; and 4=800. Docetaxel 80 mg/m2 IV was administered day 8, with pegfilgrastim day 9 each cycle. Treatment was continued until disease progression, unacceptable toxicity, or symptomatic deterioration. The trial was monitored using the Time to Event Continual Reassessment Method, targeting a 20% toxicity rate. Tumor biopsies were performed at baseline, after 1 cycle, and at treatment completion in a subset of patients.

Results: 30 patients were enrolled between Mar 2008 and Jan 2010. Dose limiting toxicities of the combination included diarrhea, hand-foot syndrome, and LFT elevation. 20/30 patients experienced Grade 1 or 2

fatigue. The final estimates and confidence intervals for the probability of dose limiting toxicity at each dose level are summarized in the table:

Probability = probability of dose-limiting toxicity 20 enrolled patients had measurable disease by RECIST criteria. Of these, 9 had PR, 8 SD, and 3 PD, for an estimated RR of 45% to the combination. 2 patients have been maintained on therapy in excess of 22 cycles. Conclusions: Dose level 3 was identified for further study in a Phase II randomized trial. Efficacy of docetaxel was not inhibited by MK-0752, as a 45% RR in patients with measurable disease was observed. There is intriguing long term disease stabilization in 2 patients. Evidence of an effect of the combination on the stem cell population was apparent on serial biopsies as presented at SABCS Dec 2009 (Abstract # 48); additional biopsy data will be presented.

High IGF-IR Activity in Triple-Negative Breast Cancer Cell Lines Correlates with Sensitivity to IGF-IR Inhibitor BMS-754807 in This Subtype of Human Breast Cancer

BACKGROUND: Evidence implicates insulin-like growth factor-I (IGF-I) signaling in the development and progression of breast cancer. Within the last few years several drugs targeting IGF-I receptor (IGF-IR) have entered clinical trials and are showing promising early results. BMS-754807 is a new small molecule inhibitor of IGF-IR in Phase 1 clinical trials.METHODS: Minimal and maximal IC50 to BMS-754807 for monolayer proliferation was determined for a panel of 30 breast cancer cell lines. Comparative gene expression analysis was performed using publicly available gene expression among the most resistant and sensitive cell lines. Q-RT-PCR was used to validate gene expression differences. Using the IGF gene signature, we scored each expression profile in a panel of cell lines and tumorgrafts, for correlation with the IGF-induced patterns. IGF-IR and pY-IGF-IR levels were determined in human tumorgrafts by immunohistochemistry.RESULTS: Among the different tumor cell lines, sensitivity to BMS-754807 varied widely from 0.1µM to 25µM. When defining cell lines as sensitive or resistant based on the median IC50, there was a strong enrichment for triple negative (TN; ERa-/PR-/HER2-) breast cancer cell lines in the sensitive group (11/15), while luminal breast cancer cell lines were generally resistant (11/15). We identified 136 differentially expressed genes between sensitive and resistance cell lines. Sensitive breast cancer cell lines preferentially express genes such as CAV1, and CAV2 while resistant cell lines were associated with high expression of ErbB3, and SPDEF. As luminal breast cancer cell lines were generally resistant to BMS-754807, we examined the role of estrogen and ERa on the sensitivity to BMS-754807. ERa mRNA levels strongly correlated with resistance to BMS-754807. Consistent with this, estrogen-withdrawal sensitized luminal breast cancer cells to BMS-754807. Previously, we developed an IGF-I gene signature that was derived from breast cancer cells stimulated with IGF-I, and reported that the signature strongly correlated with the TN subtype of human breast cancer. Consistent with this observation, we found that the IGF-I signature was high in TN breast cancer cell lines, and the IGF-I signature correlated with sensitivity to BMS-754807. To examine this further, we measured IGF-IR and pY-IGF-IR levels in four recently developed tumorgraft models of TN human breast cancer and found strong reactivity in half of the models. Interestingly, the tumorgraft (MC1) with the highest IGF-IR levels and activity showed the strongest enrichment for the IGF-I gene signature.CONCLUSIONS: In summary, our data indicates that the IGF-I pathway is highly active in TN breast cancer and this study provides the preclinical rationale for targeting IGF-IR in this subtype of human breast cancer.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 1132.

Targeting Intrinsically-Resistant Breast Cancer Stem Cells with Gamma-Secretase Inhibitors

Background: We showed previously that tumorigenic, mammosphere-forming human breast cancer cells characterized by high CD44 and low or undetectable CD24 levels (CD44+/CD24-/low) are intrinsically resistant to conventional chemotherapy, and therefore may be responsible for cancer relapse. Our goal is identify novel drugs that selectively target these chemotherapy-resistant, tumor-initiating cells. Gene expression analysis of CD44+/CD24-/low cells vs. non-tumorigenic cells implicated the Notch, PI3K, and Hedgehog signaling pathways in regulating CD44+/CD24-/low cells. Thus, Notch, PI3K-AKT, and/or Hedgehog inhibitors may eliminate this unique subpopulation of cancer cells, either alone or in combination with chemotherapy, and could improve patient outcome. To test this hypothesis, we are carrying out a series of preclinical and clinical studies using a gamma-secretase inhibitor (GSI) to target the Notch pathway. Methods: For preclinical studies, stable xenograft lines were generated by transplantation of human tumor biopsy fragments into immunocompromised mice. Mice with tumors (n = 32, 150-300 mm3) were randomized to four treatment groups: 1) vehicle control, 2) chemotherapy: docetaxel 3) drug: GSI (MRK-003, Merck) or 4) combination: docetaxel + MRK-003. During treatment, mice were monitored for tumor volume and body weight. At the end of the treatment cycle, residual tumors were characterized by FACS for the percentage of CD44+/CD24-/low cells, as well as for mammosphere-forming efficiency (MSFE) and tumor-initiating capacity. In a complementary clinical trial, breast cancer biopsies taken before and after treatment with GSI (MK-0752, Merck) were characterized for expression of CD44, CD24, and ALDH by FACS and for MSFE. Results and Conclusions: In preclinical studies using two independent triple negative xenograft lines, Notch pathway inhibition reduced mammosphere formation but did not affect tumor volume, with no consistent change in marker expression by FACS. In patient samples, MSFE also declined after the first cycle of GSI/chemotherapy and remained low after subsequent cycles. This response corresponded with a stasis of metastatic growth during five cycles of treatment, but metastatic burden began to increase coincident with the sixth cycle of treatment. Marker analysis suggests that GSI treatment chemo-sensitizes a significant proportion of the otherwise chemo-resistant CD44+/CD24-/low cell population indicating that they are dependent on the Notch pathway for survival. The decrease of MSFE in both preclinical and clinical studies suggests that inhibition of the Notch pathway by GSI may reduce the number of tumorigenic cancer cells that would otherwise remain after chemotherapy.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 48.

Clinical protocol. Purging of autologous stem cell sources with bcl-x(s) adenovirus for women undergoing high-dose chemotherapy for stage IV breast carcinoma

High-dose chemotherapy (HDCT) and autologous bone marrow transplantation (BMT) is frequently used to treat patients with metastatic cancer including breast cancer and neuroblastoma. However, the bone marrow of such patients is often contaminated with tumor cells. Recently, we have found that a recombinant adenovirus vector that contains a bcl-x, minigene (a dominant negative inhibitor of the bcl-2 family), called the bcl-x(s) adenovirus, is lethal to cancer cells derived from epithelial tissues, but not to normal human hematopoietic cells. To determine the mechanism, by which this virus spares normal hematopoietic cells, we isolated normal mouse hematopoietic stem cells and infected them with an adenovirus that contains a beta-galactosidase minigene. Such cells do not express beta-galactosidase, indicating that hematopoietic stem cells do not express transgene encoded by adenovirus vectors based upon the RSV-AD5 vector system. When breast cancer cells mixed with hematopoietic cells were infected with the bcl-x(s) adenovirus, cancer cells were selectively killed by the suicide adenoviruses. Hematopoietic cells exposed to the suicide vectors were able to reconstitute the bone marrow of mice exposed to lethal doses of y-irradiation. These studies suggest that adenovirus suicide vectors may provide a simple and effective method to selectively eliminate cancer cells derived from epithelial tissue that contaminate bone marrow to be used for autologous BMT. We therefore propose to initiate a phase I clinical trial to test the safety of this virus in women with breast cancer undergoing high does chemotherapy and autologous BMT.

Treatment of metastatic cancer with tetrathiomolybdate, an anticopper, antiangiogenic agent: Phase I study

Preclinical and in vitro studies have determined that copper is an important cofactor for angiogenesis. Tetrathiomolybdate (TM) was developed as an effective anticopper therapy for the initial treatment of Wilson's disease, an autosomal recessive disorder that leads to abnormal copper accumulation. Given the potency and uniqueness of the anticopper action of TM and its lack of toxicity, we hypothesized that TM would be a suitable agent to achieve and maintain mild copper deficiency to impair neovascularization in metastatic solid tumors. Following preclinical work that showed efficacy for this anticopper approach in mouse tumor models, we carried out a Phase I clinical trial in 18 patients with metastatic cancer who were enrolled at three dose levels of oral TM (90, 105, and 120 mg/day) administered in six divided doses with and in-between meals. Serum ceruloplasmin (Cp) was used as a surrogate marker for total body copper. Because anemia is the first clinical sign of copper deficiency, the goal of the study was to reduce Cp to 20% of baseline value without reducing hematocrit below 80% of baseline. Cp is a reliable and sensitive measure of copper status, and TM was nontoxic when Cp was reduced to 15-20% of baseline. The level III dose of TM (120 mg/ day) was effective in reaching the target Cp without added toxicity. TM-induced mild copper deficiency achieved stable disease in five of six patients who were copper deficient at the target range for at least 90 days.

Regulation of metastasis-related gene expression by p53: a potential clinical implication

Tumor metastasis is the main cause of mortality and treatment failure in cancer patients. It is a complex biological process regulated by alternations in expression of many genes. The p53 tumor suppressor gene has been shown to regulate expression of some metastasis-related genes. p53 transcriptionally activates expression of the genes encoding epidermal growth factor receptor, matrix metalloproteinase (MMP)-2, cathepsin D, and thrombospondin-1 but represses expression of the genes encoding basic fibroblast growth factor and multidrug resistance-1. Decreased expression of E-cadherin is associated with p53 alternations. Because these p53-regulatory genes either promote or inhibit tumor metastasis, the net effect of p53 expression on tumor metastasis depends upon the pattern of expression of these genes in a particular tumor. Because radiotherapy has been shown to increase tumor metastasis in both animal and human studies and because p53 is activated by radiation or DNA-damaging reagents, here we propose the working hypothesis that p53 may promote tumor metastasis upon induction by local radiotherapy or chemotherapy in some tumor types. For patients whose tumors contain wild-type p53, MMP inhibitors might be given with or before radiotherapy or chemotherapy to prevent an increase in tumor metastasis. Special caution should be taken with patients with cancers such as nasopharyngeal carcinoma in which p53 mutation is infrequent and radiotherapy is the main choice of treatment. To test our hypothesis, three studies are proposed and could serve as an initial step in understanding the complex biological process following radiation-induced p53 activation and its roles in regulation of tumor metastasis.

Breast conservation and prolonged chemotherapy for locally advanced breast cancer: the University of Michigan experience

PURPOSE

To determine whether breast conservation and prolonged neoadjuvant chemotherapy have efficacy in locally advanced breast cancer (LABC), as measured by survival and rate of breast conservation.

MATERIALS AND METHODS

Eighty-nine patients with stage III disease were enrolled at the University of Michigan (UM) onto a prospective nonrandomized trial. Patients received nine 21-day cycles of neoadjuvant chemohormonal therapy that consisted of doxorubicin 30 mg/m2 and cyclophosphamide 750 mg/m2 intravenously on day 1, conjugated estrogens 0.625 mg orally twice daily on days 6 to 8, methotrexate 40 mg/m2 and fluorouracil 500 mg/m2 intravenously on day 8, and tamoxifen 10 mg orally twice daily on days 9 to 14. Patients with a negative biopsy received radiation only, while those with residual disease underwent mastectomy and postoperative radiotherapy. Eight more cycles of chemohormonal therapy were administered after local-regional therapy.

RESULTS

The clinical response rate to neoadjuvant therapy was 97%, 28% of patients had a complete pathologic response evaluated at biopsy. Five-year overall and disease-free survival probabilities were 54% and 44%, respectively. The median disease-free survival time was 2.4 years. The 5-year actuarial rates of local-regional control with local failure as only first failure were 82% and 78% following radiotherapy, and mastectomy and radiotherapy, respectively (P = .99).

CONCLUSION

Prolonged neoadjuvant chemohormonal therapy and biopsy-driven local therapy have efficacy in LABC, with 28% of patients being candidates for breast conservation and a 5-year overall survival rate of 54%.

A recombinant bcl-x s adenovirus selectively induces apoptosis in cancer cells but not in normal bone marrow cells

Many cancers overexpress a member of the bcl-2 family of inhibitors of apoptosis. To determine the role of these proteins in maintaining cancer cell viability, an adenovirus vector that expresses bcl-xs, a functional inhibitor of these proteins, was constructed. Even in the absence of an exogenous apoptotic signal such as x-irradiation, this virus specifically and efficiently kills carcinoma cells arising from multiple organs including breast, colon, stomach, and neuroblasts. In contrast, normal hematopoietic progenitor cells and primitive cells capable of repopulating severe combined immunodeficient mice were refractory to killing by the bcl-xs adenovirus. These results suggest that Bcl-2 family members are required for survival of cancer cells derived from solid tissues. The bcl-xs adenovirus vector may prove useful in killing cancer cells contaminating the bone marrow of patients undergoing autologous bone marrow transplantation.

Bcl-2 protects murine erythroleukemia cells from p53-dependent and -independent radiation-induced cell death

To better understand the molecular basis of radiation-induced cell death, we studied the role of the bcl-2 oncogene and the p53 tumor suppressor gene in this process. A temperature-sensitive mutant of murine p53 (p53Val-135) and/or bcl-2 was transfected into murine erythroleukemia cells (MEL, DP16-1, which are null in p53). We demonstrate that radiation-induced cell death occurs by both p53-dependent and -independent pathways and overexpression of bcl-2 modulates both pathways. When viability was measured 24 h post-radiation, cells that had been briefly exposed to wtp53 immediately after X-ray irradiation had decreased survival as compared to unirradiated cells expressing wtp53 or X-ray irradiated DP16-1 cells. However, at later times X-ray irradiated parental DP16-1 cells also had decreased survival compared to the unirradiated control. This decrease in survival began 48 h following radiation. Bcl-2 prevented radiation-induced cell death in DP16-1 cells expressing wtp53 and delayed radiation-induced cell death in DP16-1 cells without wtp53. X-ray irradiated cells expressing wtp53 displayed microscopic and biochemical characteristics consistent with cell death due to apoptosis. DP16-1 cells which were untransfected or co-transfected with wtp53 and bcl-2 displayed characteristics of cells undergoing necrosis. These results suggest that radiation-induced cell death occurs by both p53-dependent and p53-independent pathways. The p53-dependent pathway results in cell death via apoptosis and occurs approximately 24 h following radiation. The p53-independent pathway does not appear to involve apoptosis and occurs at a later time, starting 48 h after X-ray exposure. Thus, bcl-2 protects cells from p53-dependent radiation-induced apoptotic cell death and attenuates p53-independent radiation-induced cell death.

Hemonectin mediates adhesion of engrafted murine progenitors to a clonal bone marrow stromal cell line from Sl/Sld mice

Mutant Sl/Sld mice exhibit decreased marrow hematopoiesis. The defect is known to reside in the marrow microenvironment of these animals, which is reproduced in vitro by primary marrow explants as well as by cloned marrow stromal cell lines. Bone marrow progenitor cells are incapable of adhering to primary Sl/Sld stromal cells or cloned stromal cell lines derived from them to form cobblestone-islands and proliferate. The role of hemonectin, a marrow-specific adhesion protein in the defective hematopoiesis of the Sl/Sld mice, was studied. Indirect immunoperoxidase staining of marrow in situ from Sl/Sld mice showed little specific staining while specific staining was seen in a pericellular distribution in marrow from +/+ mice. Hemonectin expression in several cloned stromal cell lines from Sl/Sld mice was compared by immunoblotting with that in cloned stromal cell lines from normal +/+ littermates. Cell line Sld3, which has the least hematopoiesis supportive capacity in vitro, showed no detectable hemonectin by immunoblotting, while Sld1 and Sld2 showed detectable but greatly reduced amounts compared with normal +/+ 2.4, GBI/6, and D2XRII. Confluent cultures incubated with purified hemonectin and engrafted with enriched progenitors showed a significant increase in the cumulative number of cobbleston-islands and day 14 spleen colony-forming units (CFU-s) forming progenitors (39.15 +/- 3.6/dish; 16.3 +/- 3.1/dish, respectively), compared with untreated Sld3 cultures (cobblestone-islands 8.1 +/- 3.6/dish; CFU-s forming progenitors 8.8 +/- 0.05/dish). Hemonectin-mediated progenitor cell binding to the Sld3 stromal cells was specifically inhibited by antihemonectin but not by preimmune serum. These data support the role of hemonectin in early progenitor-stromal cell interactions.

Protooncogene expression in normal and psoriatic skin

The expression of the c-myc, c-fos, c-jun, c-erbB, and c-Ha-ras protooncogenes was compared by Northern blot analysis of total RNA extracted from keratome biopsies of normal skin and psoriatic plaques. Isolation of intact RNA from frozen tissue required careful attention to technique during the early stages of extraction. Densitometric analysis revealed 1.5- to 2.5-fold elevations of c-myc transcript levels in lesional psoriatic relative to normal epidermis. Similar increases in cyclophilin and lipocortin II transcripts were also observed and may reflect characteristic differences in RNA preparations from normal and psoriatic epidermis. C-myc, c-jun, c-erbB, c-fos, and c-Ha-ras transcript levels were not significantly increased in lesional psoriatic epidermis when protooncogene mRNA levels were normalized to those of the cyclophilin or lipocortin genes. In contrast, transforming growth factor-alpha (TGF-alpha) transcripts were significantly increased (10- to 20-fold) with or without prior normalization. C-myc, c-fos, and c-jun transcripts were significantly induced over in vivo levels 2-4 h after organ culture of normal or psoriatic keratome biopsies, demonstrating that these genes can be highly expressed in the context of tissue injury. Our results suggest that overexpression of these protooncogenes per se is not central to the pathogenesis of psoriatic epidermal hyperplasia.

Attachment of neuroblastoma cells to extracellular matrix: correlation with metastatic capacity

Extracellular matrix (ECM) serves important attachment functions during organogenesis in mammalian species. When layered on a plastic surface, ECM extracted from the rat lung, liver, or kidney enhances the attachment of C1300 murine neuroblastoma cells to that surface. Enhanced attachment to ECM by these cells correlates with their potential to form metastatic deposits in vivo. Conversely, neuroblastoma cells selected for increased metastatic potential by in vivo passaging demonstrate enhanced attachment to organ-derived ECM. However, although ECM provides attachment sites for these murine neuroblastoma cells, the attachment is not preferential for any of the organ ECMs tested (lung, liver, kidney). Histopathologic examination of the murine liver, lungs, and kidneys performed 20 to 22 days after intravenous inoculation of C1300 cells reveals notable metastatic seeding in each of these organs, but the liver clearly exhibits a greater degree of replacement by tumor metastases than the lungs or the kidneys. Therefore, the data from the attachment assays, coupled with the histopathologic findings obtained after tumor inoculation, suggest that although the ability to attach to ECM correlates with metastatic potential, additional factors are important in determining the preferential pattern of metastatic disease observed in murine neuroblastoma.

Cell surface alpha-D-galactopyranosyl end groups: use as markers in the isolation of murine tumor cell lines with different cancer-causing potentials

Cell lines from 2 3-methylcholanthrene-induced murine tumors were established in culture and examined for reactivity with Griffonia simplicifolia isolectin B4 (GS I-B4), a lectin that has strict specificity for terminal alpha-D-galactopyranosyl residues. Virtually all of the cells in both populations were strongly reactive, indicating the presence of this carbohydrate on the cell surface. Both tumor lines were exposed to human serum with antibodies to the blood group B antigen. More than 99.99% of the exposed cells were killed by this treatment. This is not surprising, because terminal alpha-D-galactopyranosyl residues comprise the blood group B antigen. From the few surviving cells, it was possible to establish cell lines resistant to the cytotoxic effects of the anti-blood group B antibodies. A total of 4 cell lines were independently obtained in this way. The human serum-resistant lines showed no detectable reactivity with GS I-B4, indicating that alpha-D-galactopyranosyl-deficient cell lines had been obtained. The parent and variant cells were compared for reactivity with anti-laminin antibodies. Both parent lines showed strong reactivity by immunofluorescence in the viable state, whereas the alpha-D-galactopyranosyl-deficient lines showed no reactivity. The parent and variant lines were also compared with regard to in vitro and in vivo growth. The alpha-D-galactopyranosyl-deficient lines had reduced in vitro growth capacity relative to the parent lines. More importantly, in contrast to the parent lines, these lines were significantly less tumorigenic than the parent lines when injected into syngeneic mice and did not metastasize spontaneously.

Developmental changes in the ovarian follicular basal lamina detected by immunofluorescence and electron microscopy

Alterations in the basal lamina (BL) of developing follicles were studied by immunofluorescent microscopy using antibodies against type IV collagen, laminin, and fibronectin, and by electron microscopy. Ovarian development was induced in immature rats by sequential administration of estradiol, follicle-stimulating hormone (FSH) and human chorionic gonadotropin (hCG). A continuous BL was observed in healthy follicles treated with estradiol and FSH. As determined by immunofluorescence, laminin, type IV collagen, and fibronectin were restricted to the BL and the theca but not to the granulosa. When follicles were allowed to undergo atresia or induced to ovulate with hCG, the BL became fragmented. This was confirmed by electron microscopy of healthy, atretic, and luteinizing follicles which showed that in healthy follicles the BL was continuous, whereas in both atretic and luteinizing follicles, it was fragmented. Atresia was also associated with the penetration of thecal cells into the follicles. These observations indicate that the intact BL present in healthy follicles undergo extensive changes during atresia and ovulation.

Differential expression of a lamininlike substance by high- and low-metastatic tumor cells

High-metastatic murine fibrosarcoma cells readily attached to Type IV (basement membrane) collagen, whereas low-metastatic cells isolated from the same tumor did not. The addition of laminin--a glycoprotein that facilitates the adherence of epithelial cells to their basement membranes--enhanced the attachment of the low-metastatic cells, but not the high-metastatic cells. Using anti-laminin antibodies and a laminin-binding lectin as probes, the authors were able to identify by immunofluorescence a moiety associated with the high-metastatic cells, but not the low-metastatic cells, which cross-reacted with murine laminin purified from the EHS sarcoma. When extracts from the high-metastatic cells were separated by affinity chromatography, with the laminin-binding lectin as the affinity substrate, a substance was isolated that had an apparent molecular weight of 56,000 daltons. The affinity-purified material reacted strongly with anti-laminin antibodies by enzyme-linked immunosorbent assay.

Factors affecting the growth of head and neck squamous carcinoma cell lines

Cell plating density influences the growth pattern of human squamous cell carcinoma (SCC) cell lines in culture. SCC lines were used to study factors responsible for these effects. Experiments in which the medium was changed daily or in which conditioned medium was used showed that the growth-supporting factors were not found in the media. However, when cells were plated in dishes in which the same cell line had been grown to confluence and removed by scraping, logarithmic growth began immediately. The effect was not seen on areas of the plate that had been covered with coverslips or in dishes where fibroblasts had been cultured. Antibodies to fibronectin, laminin, and a variety of epidermal cell antigens were used to determine the nature of the growth-stimulating substances remaining on the dish following cell removal. Results indicate that an extracellular matrix with similarities to basement membranes was present on the conditioned dishes.