Impact of the COVID-19 pandemic on melanoma diagnosis and presentation: a `review

The ongoing challenges posed by COVID-19 are concerning for their impact on successful detection and recognition of melanoma as total body skin examinations and skin biopsies are critical for identifying early-stage melanoma and intervening before progression to metastatic disease. A comprehensive electronic search of PubMed/MEDLINE was conducted on or before August 1, 2022, using the search terms ("skin" AND "COVID-19"), (["skin cancer" AND "COVID-19"] OR ["skin cancer" AND "coronavirus"]), (["melanoma" AND "COVID-19"] OR ["melanoma" AND "coronavirus"]), ("dermatology" AND "COVID-19"), and ("cutaneous" AND "COVID-19"). Eight articles representing Belgium, Chile, France, Germany, Spain, the United Kingdom, and the United States were included. Four articles analyzed changes in the proportion of in situ melanoma at diagnosis and consistently reported decreases, with an overall decrease ranging from 7.6 to 40.4%. Five studies analyzed changes in the proportion of melanoma diagnoses by staging, but no clear changes in staging patterns were observed. Five studies analyzed changes in the mean Breslow thickness of melanoma diagnoses and consistently reported increases, with an overall increase ranging from 4.0 to 38%. Disruptions to proper diagnosis and treatment of melanoma are creating undue morbidity, mortality, and healthcare costs as the pandemic continues. Continued research with improved, centralized data collection is needed to better address the COVID-19 pandemic's ongoing challenge to appropriate detection and treatment of melanoma.

Targeting of palpable B16-F10 melanoma tumors with polyclonal antibodies on white blood cells

BACKGROUND

Antibodies and other recognition molecules direct cancer cell death by multiple types of immune cells. Therapy directed at only one target typically results in tumor regrowth because of tumor heterogeneity. Our goal is to direct therapy to multiple targets simultaneously. Our previous studies showed that multiple antibodies targeting mutated tumor proteins inhibited tumor growth when injected subcutaneously near the time of cancer cell implantation.

METHODS

A cocktail of rabbit antibodies against B16-F10 cell surface related mutated proteins were generated. Implanted B16-F10 cells were allowed to grow to palpable size before treatment. Antibodies were administered using different routes of exposure. Free antibody was compared to antibody armed on mouse splenic white blood cells (WBCs). Binding of the antibody cocktail was determined for mouse and human WBCs.

RESULTS

The antibody cocktail inhibited tumor growth and prolonged survival when administered as free antibody or armed on WBCs. The antibody cocktail armed on WBCs achieved similar tumor inhibition as free antibody but at a dose 1000-fold less. Armed WBCs achieved tumor inhibition by intravenous and subcutaneous administration. The antibody cocktail bound well to human WBCs and saturation dose was defined. Binding was stable under simulated in vivo condition in human plasma at 37 °C.

CONCLUSIONS

Antibodies targeting multiple tumor mutated proteins inhibited tumor growth and prolonged survival. Effective antibody dose was reduced 1000-fold by arming WBCs. Rabbit antibodies saturated human WBCs using <1 mg per billion cells. A phase I trial in cancer patients using this strategy has been approved by the FDA.

Development of Clinical-Grade Antibodies against Tumor-Specific Mutations to Target Neuroblastoma

OBJECTIVE

Tumor heterogeneity is a fundamental problem in treating cancer with monotargeting therapy, including chemical, antibody, and T cell therapies. Our goal is to target multiple mutated peptides found in a patient's cancer to increase antibody therapy effectiveness.

METHODS

Tumor samples were derived from patients with neuroblastoma. Whole-exome sequencing was performed of tumor and normal cells. Mutated proteins with missense mutations were selected from the patient tumor. These mutated proteins were further selected for the presence of missense mutations in the outer cell surface. Peptides representing a mutated section of the proteins were used for vaccinating rabbits and generating anti-peptide antibodies. The binding of individual polyclonal antibodies (pAbs) and the mixtures of pAbs were determined against the patient's tumor as cultured neuroblastoma cells and in a murine xenograft model. Antibodies were prepared according to FDA requirements of a phase I clinical protocol.

RESULTS

All of the generated rabbit pAbs bound with high affinity to the corresponding peptide used for vaccination. The pAbs also bound to low passage neuroblastoma cells. Mixed as cocktails, the pAbs had substantially increased binding to cells and bound well to the xenograft tissue. No binding was observed to the panel of normal human tissues. Preparation of pAbs by an academic lab to clinical-grade was approved by FDA for phase I clinical trial.

CONCLUSION

We describe a new strategy to make customized antibodies for individual cancer patients and present the data required to meet FDA specifications to begin a phase I clinical trial.

Abstract PO-047: Extraction and organization of all published results on impact of systemic racism on treatment of cancer patients

Statement of the problem: Unconscious bias and systemic racism is evident in published reports that describe persistent asymmetric outcomes in our entire health care system including oncology. Framework of the solution: There already is a very large set of publications that describe the extent and outcomes of health disparities. An extensive data set also describes mitigation strategies. Changing the outcomes includes policy changes within the health care system but also with regulatory agencies and the legislative branch of government. It is critical that these different systems are armed with the totality of available information in a manner that can be leveraged to improve the health care of all. We have developed a system of describing large sets of data manually extracted from published articles. These results are aggregated together independent of the framework of the manuscript so that similar outcomes can be placed side by side. This system can provide the necessary comprehensive data that is available today to begin to implement changes. Results to date: We have used COVID-19 publications as a prototype topic that has so many articles no single person can comprehend or manage. We extracted data from 1000 COVID-19 manuscripts that presented new data. This rendered 26,000 note fields arranged in a parent child relationship. The data base described 12,000 individual observations. A read only version is available at COVIDpublications.org. We are now applying this system to bias and stigma of the health care profession to persons who use drugs, and a demo of this project is available at (https://app.refbin.com/app/embed?m=1188). We have now established the rules to manually extract data from any clinical article that presents new data. This involves 4 types of note fields per observation arranged in parent child relationships. 1) The observation, 2) description of the observation, 3) the population, and 4) the topic. This system allows the observations from an unlimited number of studies to share parents. This results in about a 5-fold reduction in the total number of note fields. It also allows grouping of information so that a user can scan the data base and access the entirety of information without specifically knowing what they are looking for. Conclusions: We are expanding this data base bias and systemic racism of the health care system on persons with substance use disorder to include the broader range of patients. By capturing all of the data that is known we hope to influence implementation of improved health care to patients including those with cancer. These results will be presented in October.

Citation Format: Shania Lunna, Samuel Gauthier, Stacia Richard, Rachel M Bombardier, David N Krag. Extraction and organization of all published results on impact of systemic racism on treatment of cancer patients [abstract]. In: Proceedings of the AACR Virtual Conference: 14th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2021 Oct 6-8. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr PO-047.

Preparation of clinical-grade WBCs using leukocyte reduction filters

OBJECTIVE

Our goal was to develop a simpler and less expensive method of obtaining human clinical-grade WBCs using an alternative method to continuous leukapheresis. Our purpose for the WBCs is to arm them with rabbit anticancer antibodies for a phase I clinical trial.

METHODS

Using leukocyte reduction filters (LRFs) discarded from the blood bank, we evaluated multiple variables to maximize recovery of WBCs with the lowest contamination of RBCs. Using an optimized protocol, full-scale runs according to FDA current Good Manufacturing Practice (cGMP) standards were completed with immediate filtration of blood obtained from donors participating in our study.

RESULTS

Forward flushing of the filter removed 85% to 95% of residual RBCs and platelets. When backward flushed with 800 mL, 95% of the WBCs recovered were contained in the first 400 mL. The number of recovered WBCs was in the range of 166-211 million/100 mL filtered blood. Subpopulations of WBCs recovered from the LRFs were in the same proportion as the donors' whole blood. Viability of recovered WBCs was 96-99%. Exogenous rabbit antibodies bound well to the recovered WBCs and were retained for at least 5 h without significant reduction. Three full scale runs of WBCs recovered from donor blood filtered through the LRF met all FDA specification of sterility, endotoxin levels, viability and stability.

CONCLUSION

Using LRFs, high quality clinical grade WBCs are readily obtained in quantities of 0.2 to 1.2 billion cells from 100 mL to 450 mL (1 unit) of whole blood.

A cocktail of polyclonal affinity enriched antibodies against melanoma mutations increases binding and inhibits tumor growth

BACKGROUND

Antibodies that target a single tumor antigen fail to cure stage IV cancer patients due to tumor heterogeneity and variable expression of antigen. Tumor cells with insufficient binding of antibody will not undergo antibody induced cytotoxicity. We describe targeting multiple tumor-specific antigens that resulted in homogeneous dense binding to mouse melanoma cells and significant tumor growth inhibition.

METHODS

Surface-related tumor-specific mutations on B16-F10 cells were identified. Peptides containing the single amino acid mutation were synthesized for 9 different neoantigens. Rabbits were vaccinated with each of these peptides and high affinity polyclonal antibodies to each peptide were obtained. The 9 antibodies were combined as a cocktail and mice with implanted B16-F10 cells were treated with and without PD1 inhibitor.

RESULTS

Even a single dose of the antibody cocktail inhibited tumor growth and prolonged survival. PD1 inhibitor alone had little effect on tumor growth. The antibody cocktail plus PD1 inhibition increased tumor response and 4 doses of the cocktail completely prevented tumor growth in 50% of the mice. Complete responses were durable. The complete responders were highly resistant to tumor re-challenge at 6 months. No adverse events were identified in the antibody treated mice.

CONCLUSIONS

Multiple tumor-specific cell surface-related neoantigens were abundant in B16-F10 cells. Antibodies to 9 of these neoantigens had variable binding but when combined had dense homogeneous binding. Even one dose of this cocktail of 9 antibodies improved survival and when multiple doses were combined with PD1 inhibition 50% of the mice were rendered permanently tumor free.

Multiple antibodies targeting tumor-specific mutations redirect immune cells to inhibit tumor growth and increase survival in experimental animal models

BACKGROUND

T cell therapy for cancer involves genetic introduction of a target-binding feature into autologous T cells, ex vivo expansion and single large bolus administration back to the patient. These reprogrammed T cells can be highly effective in killing cells, but tumor heterogeneity results in regrowth of cells that do not sufficiently express the single antigen being targeted. We describe a cell-based therapy that simultaneously targets multiple tumor-specific antigens.

METHODS

High-affinity polyclonal rabbit antibodies were generated against nine different surface-related tumor-specific mutations on B16F10 cells. Unsorted splenic effector cells from syngeneic mice were incubated with a cocktail of the nine anti-B16F10 antibodies. These 'armed' effector cells were used to treat mice previously inoculated with B16F10 melanoma cells.

RESULTS

The cocktail of nine antibodies resulted in dense homogeneous binding to histological sections of B16F10 cells. Five treatments with the armed effector cells and PD1 inhibition inhibited tumor growth and improved survival. Shortening the interval of the five treatments from every three days to every day increased survival. Arming effector cells with the four antibodies showing best binding to B16F10 cells even further increased survival.

CONCLUSIONS

This study demonstrates that ex vivo arming a mixed population of immune effector cells with antibodies targeting multiple tumor-specific mutated proteins in conjunction with PD1 inhibition delayed tumor growth and prolonged survival in mice inoculated with an aggressive melanoma. A remarkably low total antibody dose of less than 5 µg was sufficient to accomplish tumor inhibition. Scaling up to clinical level may be feasible.

Abstract 552: Anti-tumor effects of anti-neoantigen antibodies: Tumor growth retardation and increased survival in a syngeneic model of cancer

This study was designed to decrease tumor growth by treatment with multiple anti-neoantigen antibodies (Abs) combined with PD1 inhibition. Dramatic reduction in tumor growth was observed. Despite tremendous excitement of checkpoint inhibitors only a minority of patients have durable complete responses. Success of checkpoint inhibitors appears related to the immune response to neoantigens. We investigated the potential enhancement of checkpoint inhibitors by directing a cocktail of antibodies to multiple neoantigens simultaneous with PD1 inhibition. The choice of neoantigens was simply based on the potential rabbit humoral immunogenicity of a mutated epitope present at the tumor cell surface or secretary proteins, without assigning any weightage to the protein function. Rabbits were vaccinated with each of the 9 selected mutated epitopes of B16-F10 melanoma tumor proteins for generating antibodies. Rabbit polyclonal Abs were affinity purified for each antigen with EC50s mostly in picomolar range. All 9 polyclonal antibodies were mixed equally as a cocktail for treatment experiments. The tumor model was C57BL/J strain of mice implanted with 3x105 B16-F10 melanoma tumor cells in their dorsal flank region. The treatment with anti-neoantigen Abs cocktail were administered in two different schedules; 1) a single treatment by implanting tumor cells suspended in 0.2 mg Abs cocktail/mouse and 2) local injection (0.2 mg Abs cocktail/mouse) into the tumor implantation site on 3, 6, 9 and 13 days post-tumor implantation. Except for a completely untreated control group all mice received 4 intraperitoneal injections (0.2 mg/mouse) of anti-mouse PD1 Ab (clone RMP1-14) or its isotype control Ab (IgG2a, k). Normal rabbit polyclonal IgG was used as control against the 9 anti-neoantigen Abs cocktail. No treatment resulted in rapid growth of large tumors and these untreated mice either died or were euthanized by day 20. The treatment with anti-PD1 Ab or its isotype control Ab alone did not affect tumor growth and survival in comparison to untreated mice. Furthermore, PD1 inhibition combined with normal rabbit IgG had no effect on tumor growth or survival. However, the single treatment of tumor cells with the 9 Abs cocktail during implantation combined with PD1 inhibition significantly retarded tumor growth and increased survival. The results were even more dramatic with the group of mice that were implanted with tumor cells in PBS and received 4 treatments of the 9 Abs cocktail in combination to PD1 inhibition. All the animals in this group had substantial retardation of tumor growth and 50% of the mice have shown no tumor whatsoever out to post-implantation day sixty. This is the first study to show anti-tumor effects of multiple anti-neoantigen Abs. These results are important particularly in a poorly immunogenic tumor model which is non-responsive to PD1 checkpoint inhibitor therapy alone.

Citation Format: Girja S. Shukla, Yu-Jing Sun, Stephanie C. Pero, David N. Krag. Anti-tumor effects of anti-neoantigen antibodies: Tumor growth retardation and increased survival in a syngeneic model of cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 552.

Sentinel lymph node B cells can predict disease-free survival in breast cancer patients

Tumor invasion into draining lymph nodes, especially sentinel lymph nodes (SLNs), is a key determinant of prognosis and treatment in breast cancer as part of the TNM staging system. Using multicolor histology and quantitative image analysis, we quantified immune cells within SLNs from a discovery cohort of 76 breast cancer patients. We found statistically more in situ CD3⁺ T cells in tumor negative vs. tumor positive nodes (mean of 8878 vs. 6704, respectively, p = 0.006), but no statistical difference in CD20⁺ B cells or CD1a⁺ dendritic cells. In univariate analysis, a reduced hazard was seen with a unit increase in log CD3 with HR 0.49 (95% CI 0.30–0.80) and log CD20 with HR 0.37 (95% CI 0.22–0.62). In multivariate analysis, log CD20 remained significant with HR 0.42 (95% CI 0.25–0.69). When restricted to SLN tumor negative patients, increased log CD20 was still associated with improved DFS (HR = 0.26, 95% CI 0.08–0.90). The CD20 results were validated in a separate cohort of 21 patients (n = 11 good outcome, n = 10 poor outcome) with SLN negative triple-negative breast cancer (TNBC) (“good” mean of 7011 vs. “poor” mean of 4656, p = 0.002). Our study demonstrates that analysis of immune cells within SLNs, regardless of tumor invasion status, may provide additional prognostic information, and highlights B cells within SLNs as important in preventing future recurrence.

B cells within the tumor-draining lymph nodes may have an important biological role in preventing relapse of breast cancer. A team led by Peter Lee from City of Hope in Duarte, California, USA, quantified the levels of three populations of immune cells—T cells, B cells and dendritic cells—within sentinel lymph nodes biopsied from a cohort of 76 patients. They found that larger numbers of T cells and B cells were both linked to longer progression-free survival in the women. However, after statistically accounting for correlations between the two immune cell types, the researchers concluded that B cells had the dominant beneficial effect on survival times. They validated the finding that high B-cell counts are a prognostic indicator of better outcomes in a separate cohort of 21 women with triple-negative breast cancer.

Identification of tumor-reactive B cells and systemic IgG in breast cancer based on clonal frequency in the sentinel lymph node

A better understanding of antitumor immune responses is the key to advancing the field of cancer immunotherapy. Endogenous immunity in cancer patients, such as circulating anticancer antibodies or tumor-reactive B cells, has been historically yet incompletely described. Here, we demonstrate that tumor-draining (sentinel) lymph node (SN) is a rich source for tumor-reactive B cells that give rise to systemic IgG anticancer antibodies circulating in the bloodstream of breast cancer patients. Using a synergistic combination of high-throughput B-cell sequencing and quantitative immunoproteomics, we describe the prospective identification of tumor-reactive SN B cells (based on clonal frequency) and also demonstrate an unequivocal link between affinity-matured expanded B-cell clones in the SN and antitumor IgG in the blood. This technology could facilitate the discovery of antitumor antibody therapeutics and conceivably identify novel tumor antigens. Lastly, these findings highlight the unique and specialized niche the SN can fill in the advancement of cancer immunotherapy.

Vaccine-draining lymph nodes of cancer patients for generating anti-cancer antibodies

Background

Our research is focused on using the vaccine draining lymph node to better understand the immune response to cancer vaccines and as a possible source of anti-cancer reagents. We evaluated vaccine draining lymph nodes archived from a clinical study in melanoma patients and determined the reaction of B cells to the vaccine peptides.

Methods

Mononuclear cells (MNCs) were recovered from cryopreserved lymph nodes that were directly receiving drainage from multi-peptide melanoma vaccine. The patients were enrolled on a vaccine study (NCT00089219, FDA, BB-IND No. 10825). B cell responses in the vaccine-draining lymph nodes were studied under both stimulated and un-stimulated conditions. Cryopreserved cells were stimulated with CD40L, stained with multiple human cell-surface markers (CD19, CD27, IgM) to identify different categories of B cell sub populations with flow cytometry. Hybridomas were generated from the lymph node cells after CD40L-stimulation. Cells were fused to murine plasmacytoma P3X63.Ag8.653 using Helix electrofusion chamber. ELISA was used to evaluate hybridoma derived antibody binding to vaccine peptides.

Results

Viable MNCs were satisfactorily recovered from lymph nodes cryopreserved from six vaccine study patients 8–14 years previously. B cell ELISPOT demonstrated responses for each patient to multiple vaccine peptides. CD40L stimulation of lymph node cells increased the proportion of CD19⁺ CD27⁺ cells from 12 to 65% of the sample and increased the proportion of class-switched cells. Screening of IgG secreting clones demonstrated binding to melanoma vaccine peptides.

Conclusions

B cells were successfully recovered and expanded from human cryopreserved vaccine-draining lymph nodes. Individual B cells were identified that secreted antibodies that bound to cancer vaccine peptides. The ability to reliably generate in vitro the same antibodies observed in the blood of vaccinated patients will facilitate research to understand mechanisms of human antibody activity and possibly lead to therapeutic antibodies.

Vaccine draining lymph nodes are a source of antigen-specific B cells

PURPOSE

Our research is focused on using vaccine draining lymph nodes as a source of immune cells to better understand the immune response and to attempt to generate new anti-cancer reagents. Following a vaccine, harvesting the lymph node can only be done once. We endeavored to determine the range of times that B cells secreting anti-KLH antibodies were present in the node of KLH-vaccinated mice.

RESULTS

Following vaccination the total number of mononuclear cells (MNCs) increased in the vaccine-draining lymph node (VDN). The percentage of MNCs that were B cells nearly doubled. B cells recovered from the node that secreted anti-KLH antibodies were evident by day 7. The number continued to increase and then slowly decreased over the observed time range to 28days after vaccination. The VDN, compared to the spleen, the bone marrow and the nonVDN, contained a higher percentage of B cells that secreted anti-KLH antibodies.

CONCLUSIONS

After a vaccine, there is a multi-week window of time when an increasing number of B cells are present in a VDN that secrete anti-KLH antibodies. These results support using the VDN as a source for B cells that secrete anti-vaccine antibodies.

Abstract 581: Bone marrow-derived B-cell hybridomas from neuroblastoma patients generate antibodies that bind to patients’ own tumors

Today antibody therapy is considered to be one of the most important and successful strategies to treat a variety of cancers. For example, the addition of antibodies such as Herceptin and Avastin to a chemotherapy regimen has shown improved survival in the treatment of breast cancer and colorectal cancer, respectively. Main problems with this kind of therapy are that many patients are not candidates because their tumors do not overexpress the drug target and that patient develop resistance to the targeted drug. A method to rapidly develop different sets of therapeutic antibodies would greatly contribute to the field of targeted anticancer therapy. This work evaluated the feasibility of using residual clinical material from pediatric neuroblastoma patients to generate antibodies to autologous tumor. Neuroblastoma is the most common extracranial solid tumor in children, accounting for 8-10% of all childhood cancers. Most patients with neuroblastoma are young and commonly present with metastatic disease. Bone marrow aspirate from neuroblatoma patients was the source material for the mononuclear cells and the tumor cells used in present study. Tumor cells were cultured and xenograft tumors were produced in mice. Hybridomas were generated by electrofusion of stimulated bone marrow mononuclear cells with plasmacytoma P3×63.Ag8.653 under hypo-osmolar condition using Eppendorf Multiporator/Helix chamber. Following hypoxanthine-aminopterin-thymidine (HAT) selection and monoclonal distribution, the culture supernatants were assayed for immunoglobulin secretion by ELISA. The supernatants from the positive clones were evaluated by immunofluorescence microscopy for binding to cultured neuroblastoma cells and neuroblastoma xenograft tissue sections derived from the same patient from which the hybridomas were generated. The results demonstrated that multiple hybridomas of bone marrow mononuclear cells secreted monoclonal antibodies that bound autologous neuroblastoma cells. Further evaluation of the tumor-binding antibodies on a panel of normal human tissues showed no binding to most of the tissues in the panel. Successful outcome of these experiments demonstrate the feasibility of generating human monoclonal antibodies from residual marrow specimens that bind autologous neuroblastoma cells. However, it remains to be determined whether these antibodies are bioactive and whether this approach will be generally applicable in more patients with neuroblastoma. It may be concluded that the strategy described here, which exploits the cancer patient's own immune repertoire, has a great potential for neuroblastoma target discovery and developing antibodies with possible therapeutic and/or diagnostic utility in cancer.

Citation Format: Girja S. Shukla, Giselle S. Sholler, Yujing Sun, Stephanie C. Pero, Chelsea L. Carman, Ping Zhao, David N. Krag. Bone marrow-derived B-cell hybridomas from neuroblastoma patients generate antibodies that bind to patients’ own tumors. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 581.

Abstract 5019: Characterization of sentinel node-derived antibodies from breast cancer patients

Lymph nodes are one of the important sites in the body where immune responses to antigens are initiated. The tumor-draining lymph node or sentinel node is the first site where cancer cells and cancer-related antigens are most likely to spread. In response to antigen exposure and immune activation, the lymph node B cells undergo clonal expansion and somatic hypermutation, leading to the affinity-matured populations of effector B cells secreting antibodies that bind to the tumor. The cancer-draining node is therefore an ideal source of B cells that produce anticancer antibodies. In the present investigation, we have characterized the antibodies derived from immortalization of sentinel node B cells from 29 breast cancer patients. The antibodies were screened for their isotypes and for binding to breast cancers classified as luminal A, luminal B, HER2, and basal/normal subtypes, based on the expressions of estrogen, progesterone and HER2 receptors. The isotype analysis showed a higher percentages of antibodies belong to IgG (48%) and IgM (34%) isotypes along with a smaller share of IgA (18%). The cell-binding studies were conducted using ELISA, immunofluorescence microscopy, and flow cytometry techniques. Of the studied antibodies, about 28% showed binding to the tumor cells. The comparative studies of antibody-binding to breast tumor cells and non-cancer breast cells identified several antibodies showing differential binding profile. The binding analyses also demonstrated that all of the tumor-binding antibodies belonged to IgM isotype. It is evident from the results that the tumor-reactive antibodies are generated in the sentinel nodes of breast cancer patients; however, the absence of class-switched anti-tumor antibodies in the repertoire raises a possibility of tumor-induced node suppression leading to an inefficient humoral immune response towards tumor antigens. The results are important in assessing the tumor immune response/lymph node suppression, and the possible role of the autoantibodies in diagnosis and therapy of breast cancer.

Citation Format: Girja S. Shukla, Stephanie C. Pero, Yu-Jing Sun, Chelsea L. Carman, David N. Krag. Characterization of sentinel node-derived antibodies from breast cancer patients. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5019. doi:10.1158/1538-7445.AM2015-5019

Autologous antibodies that bind neuroblastoma cells

Antibody therapy of neuroblastoma is promising and our goal is to derive antibodies from patients with neuroblastoma for developing new therapeutic antibodies. The feasibility of using residual bone marrow obtained for clinical indications as a source of tumor cells and a source of antibodies was assessed. From marrow samples, neuroblastoma cells were recovered, grown in cell culture and also implanted into mice to create xenografts. Mononuclear cells from the marrow were used as a source to generate phage display antibody libraries and also hybridomas. Growth of neuroblastoma patient cells was possible both in vitro and as xenografts. Antibodies from the phage libraries and from the monoclonal hybridomas bound autologous neuroblastoma cells with some selectivity. It appears feasible to recover neuroblastoma cells from residual marrow specimens and to generate human antibodies that bind autologous neuroblastoma cells. Expansion of this approach is underway to collect more specimens, optimize methods to generate antibodies, and to evaluate the bioactivity of neuroblastoma-binding antibodies.

Abstract 3638: Vaccine-draining lymph nodes of cancer patients for generating anticancer antibodies

Human vaccine studies regularly demonstrate vaccine-induced antibodies in the blood. Characterization of these antibodies shows that they exhibit an extensive range of bioactive mechanisms. Unfortunately, there is not yet a reliable method by which to produce these important antibodies. Human antibodies may not require any molecular modification for therapeutic application and have a much faster pipeline to clinical studies than animal-derived antibodies. Lymph nodes are the primary destination of tumor or vaccine antigens. In the node, B cells undergo clonal expansion and somatic hypermutation, leading to the affinity-matured populations of effector B cells secreting antibodies that bind to the tumor or vaccine. The cancer vaccine-draining node is the ideal source of B cells that produce anticancer antibodies. Despite multiple human cancer vaccine studies, very little research has been done to recover the B cells responsible for vaccine-induced anticancer antibodies. In the present study, we used mononuclear cells from surgically removed vaccine-draining lymph nodes of melanoma patients vaccinated with 6 melanoma peptides derived from cancer-testis antigens and from melanocytic differentiation proteins for generating anti-vaccine peptide antibodies. The lymph node draining the vaccination site was localized by lymphatic mapping with a radiotracer. The development and maturity of B cells were assessed by determining phenotypic characters of lymph node cells using multicolor flow cytometry. The results showed that these vaccine-draining nodes contain high numbers of class-switched (CD19+CD27+IgD-IgM-) B cells and plasmablasts (CD19+CD38+IgM-). B-cell ELISpot assay was used to quantify the proportion of B cells in vaccine-draining lymph nodes that secrete anti-melanoma peptide antibodies. Positive ELISpot responses were observed in patients who also showed serum antibody-reactivity towards the vaccine peptides. The identification of lymph node cell samples exhibiting strong B-cell responses allows efficient generation and screening of hybridomas that secrete antibodies against cancer vaccine antigens. This study establishes a step-wise protocol for generating anti-cancer antibodies from vaccine-draining lymph nodes. We anticipate that the ability to reliably generate in vitro the same antibodies observed in the blood of vaccinated patients will further stimulate research to understand mechanisms of human antibody activity.

Citation Format: Girja S. Shukla, Stephanie C. Pero, Yu-jing Sun, Chelsea L. Carman, Walter C. Olson, Craig L. Slingluff, David N. Krag. Vaccine-draining lymph nodes of cancer patients for generating anticancer antibodies. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3638. doi:10.1158/1538-7445.AM2014-3638

Radiolabeled Sentinel Node Biopsy: Collaborative Trial with the National Cancer Institute

The objective of this study was to maximize the success rate of sentinel node (SN) localization in breast cancer patients with the tracer that demonstrated the highest initial success during a preliminary evaluation. Altogether, 145 patients with operable invasive breast cancer and clinically negative lymph nodes were studied. Technetium 99m (99mTc)-sulfur colloid was injected into the breast parenchyma surrounding the invasive cancer or the biopsy cavity. Variable volumes of tracer, amounts of 99mTc, and duration of time between injection and surgery were evaluated. A hand-held gamma detector was used at surgery to locate and guide resection of all radioactive sentinel nodes (SNs), including those that were extraaxillary. A conventional lymphadenectomy was then performed in all cases. Based on previous studies, unfiltered sulfur colloid provided a higher success rate of SN identification than the other tracer types. Further evaluation with 99mTc-sulfur colloid demonstrated that increased volume increased the success rate of SN identification. An injection volume of 8 ml resulted in a success rate of 98%. SNs were not exclusively located in the axilla: In 8.6% of cases SNs were removed from an internal mammary location. The overall accuracy of patients with SNs resected was 98.4%, and the false-negative rate was 4.4%. It was concluded that (1) unfiltered 99mTc-sulfur colloid at a volume of 8 ml resulted in a high success rate for SN identification; (2) a significant number of the SNs were extraaxillary in location; and (3) the accuracy of the SNs for determining whether regional metastases had occurred was high. The U.S. National Cancer Institute is funding a randomized phase III clinical trial to evaluate SN resection compared to conventional axillary lymphadenectomy in clinical node-negative breast cancer patients. Major endpoints of this trial include long-term regional control and survival.

Spatial organization of dendritic cells within tumor draining lymph nodes impacts clinical outcome in breast cancer patients

BACKGROUND

Dendritic cells (DCs) are important mediators of anti-tumor immune responses. We hypothesized that an in-depth analysis of dendritic cells and their spatial relationships to each other as well as to other immune cells within tumor draining lymph nodes (TDLNs) could provide a better understanding of immune function and dysregulation in cancer.

METHODS

We analyzed immune cells within TDLNs from 59 breast cancer patients with at least 5 years of clinical follow-up using immunohistochemical staining with a novel quantitative image analysis system. We developed algorithms to analyze spatial distribution patterns of immune cells in cancer versus healthy intra-mammary lymph nodes (HLNs) to derive information about possible mechanisms underlying immune-dysregulation in breast cancer. We used the non-parametric Mann-Whitney test for inter-group comparisons, Wilcoxon Matched-Pairs Signed Ranks test for intra-group comparisons and log-rank (Mantel-Cox) test for Kaplan Maier analyses.

RESULTS

Degree of clustering of DCs (in terms of spatial proximity of the cells to each other) was reduced in TDLNs compared to HLNs. While there were more numerous DC clusters in TDLNs compared to HLNs,DC clusters within TDLNs tended to have fewer member DCs and also consisted of fewer cells displaying the DC maturity marker CD83. The average number of T cells within a standardized radius of a clustered DC was increased compared to that of an unclustered DC, suggesting that DC clustering was associated with T cell interaction. Furthermore, the number of T cells within the radius of a clustered DC was reduced in tumor-positive TDLNs compared to HLNs. Importantly, clinical outcome analysis revealed that DC clustering in tumor-positive TDLNs correlated with the duration of disease-free survival in breast cancer patients.

CONCLUSIONS

These findings are the first to describe the spatial organization of DCs within TDLNs and their association with survival outcome. In addition, we characterized specific changes in number, size, maturity, and T cell co-localization of such clusters. Strategies to enhance DC function in-vivo, including maturation and clustering, may provide additional tools for developing more efficacious DC cancer vaccines.

Sentinel node mapping in anal canal cancer: systematic review and meta-analysis

BACKGROUND & AIMS

The pathological condition of inguinal lymph nodes is an independent prognostic factor in predicting tumor recurrence and overall survival in anal canal cancer. Sentinel node mapping is a non-invasive method for the detection of inguinal lymph node involvement in anal cancer. In the current study, we conducted a comprehensive search of literature in this regard and then interpreted the final results in a systematic review and meta-analysis format.

METHODS

Medline, SCOPUS, and ISI Web of Knowledge were searched with the following search terms: (anal OR anus) AND sentinel. Outcomes of interest were inguinal detection rate and inguinal recurrence in patients receiving inguinal sparing radiotherapy due to pathologically negative inguinal sentinel nodes (false negative cases).

RESULTS

Overall 16 studies (323 patients) were included in the meta-analysis. Pooled inguinal detection rate was 86.2%: 73.4-93.4%: for studies using both blue dye and radiotracer it was 90.1% [78.7-95.8] and for studies using radiotracer alone it was 72.4% [46.3-88.9]. Pooled sensitivity was 90% [79-97%].

CONCLUSIONS

Sentinel node biopsy is a promising method for inguinal lymph node staging in anal cancer. Combined blue dye and radiotracer technique can maximize the inguinal detection rate. Location of the tumor is highly associated with the detection of inguinal sentinel nodes. Despite fairly high pooled sensitivity, no definite conclusion can be made regarding false negative rate of this technique due to low sample size and sub-optimal quality of the included studies. Large multicenter studies with long and consistent follow up are needed to definitely validate this technique in the future.

Intravenous infusion of phage-displayed antibody library in human cancer patients: enrichment and cancer-specificity of tumor-homing phage-antibodies

Phage display is a powerful method for target discovery and selection of ligands for cancer treatment and diagnosis. Our goal was to select tumor-binding antibodies in cancer patients. Eligibility criteria included absence of preexisting anti-phage-antibodies and a Stage IV cancer status. All patients were intravenously administered 1 × 10(11) TUs/kg of an scFv library 1 to 4 h before surgical resection of their tumors. No significant adverse events related to the phage library infusion were observed. Phage were successfully recovered from all tumors. Individual clones from each patient were assessed for binding to the tumor from which clones were recovered. Multiple tumor-binding phage-antibodies were identified. Soluble scFv antibodies were produced from the phage clones showing higher tumor binding. The tumor-homing phage-antibodies and derived soluble scFvs were found to bind varying numbers (0-5) of 8 tested normal human tissues (breast, cervix, colon, kidney, liver, spleen, skin, and uterus). The clones that showed high tumor-specificity were found to bind corresponding tumors from other patients also. Clone enrichment was observed based on tumor binding and DNA sequence data. Clone sequences of multiple variable regions showed significant matches to certain cancer-related antibodies. One of the clones (07-2,355) that was found to share a 12-amino-acid-long motif with a reported IL-17A antibody was further studied for competitive binding for possible antigen target identification. We conclude that these outcomes support the safety and utility of phage display library panning in cancer patients for ligand selection and target discovery for cancer treatment and diagnosis.

10-yr follow-up results of NSABP B-32, a randomized phase III clinical trial to compare sentinel node resection (SNR) to conventional axillary dissection (AD) in clinically node-negative breast cancer patients

1000

Background: NSABP B-32, the largest surgical prospective randomized phase III trial was designed to compare overall survival (OS), disease-free survival (DFS), and morbidity between SNR alone vs SNR + AD in SN negative (-) pts. We present 10 yr outcome data for primary endpoints as well as updated data on the effect of occult metastases, found later in the SN by central, detailed pathologic analysis. Methods: 5,611 women with operable, clinically N0, invasive breast cancer were randomized to SNR + AD (Group [Grp] 1) or to SNR alone with AD only if SNs were positive (Grp2). 3,989 (71.1%) of 5,611 pts were SN-. 3,986 (99.9%) of these SN- pts had follow-up information: Grp 1: 1,975, Grp 2:2,011. Median time on study was 9.4 yrs. Cox proportional hazard models adjusting for study stratification variables were used to compare OS and DFS between the two groups. Two-sided p values were used. HR values > 1 indicate a more favorable outcome in Grp 1 Results: At 10 yrs, there continues to be no significant difference in OS between the two groups (HR: 1.11, p = 0.27). 10 yr Kaplan-Meier (K-M) estimates for OS are 87.8% for SNR alone and 88.9% for SNR + AD. There continues to be no significant difference in DFS between the two groups (HR: 1.01, p=0.92). 10-yr K-M estimates for DFS were 76.9% for both groups. Occult nodal disease was originally detected in 3,884 pts (15.8%) with SN- on initial H and E analysis. Comparisons between the groups with and without occult disease yielded an adjusted HR for OS: 1.25 (p = 0.08) with an absolute difference at 10 yrs of 2.8% and a HR for DFS: 1.24 (p = 0.018) with an absolute difference of 4.1%. The cumulative incidences of local-regional events were low (10-yr values: SNR 4.0%, SNR+AD, 4.3%) and not significant (HR: 0.95, p = 0.77). Conclusions: At 10 yrs there continues to be no significant differences in OS and DFS between SNR and SNR + AD in pts with negative SN. The relative increase in risk of DFS and OS for pts with occult SN metastases remains stable. Support: PHS grants: NSABP: U10CA-12027, U10CA-37377, U10CA-69651, U10CA-69974; VT Ca Cntr: P30 CA22435; DNK: 5RO1CA074137 NCI Dpt HHS. Clinical trial information: NCT00003830.

Abstract 4736: Generation of tumor-specific antibodies from sentinel lymph nodes of breast cancer patients using hybridoma technology

The field of targeted therapy is providing an entirely new generation of highly active anticancer drugs. For example, addition of a targeted drug to a chemotherapy regimen has shown improved survival in the treatment of breast cancer (Herceptin) and colorectal cancer (Avastin). Main problems with this kind of therapy are that many patients are not candidates because their tumors do not overexpress the drug target and that patient develop resistance to the targeted drug. A method to rapidly develop different sets of therapeutic antibodies (Abs) would greatly contribute to the field of targeted anticancer therapy. Even more novel would be methods that can develop Abs derived from individual patients. The rationale behind this concept is solidly supported by a large number of SEREX studies demonstrating that the sera of cancer patients do contain autoantibodies against their own tumors. These autoantibodies may show greater cancer specificity as tolerance mechanisms usually inhibit Ab production against normal cells. We generated hybridomas from the sentinel nodes of 29 breast cancer patients. Surgically removed fresh breast tumors and sentinel nodes were used for this study. Sentinel lymph node cells were harvested by either scraping the cut surface or by removing a 2 mm slice of the nodes. Lymph nodes were mechanically disaggregated and sieved before Ficoll gradient centrifugation. The yield of lymphocytes varied from 0.5 to 50x106 cells. Following stimulation, mononuclear cells were fused with plasmacytoma P3X63.Ag8.653 under hypo-osmolar condition, using BTX Electro Cell Manipulator and microslide electrodes. Each immunoglobulin secreting clone was evaluated with ELISA for binding to a panel of breast cancer cell lines representing the 4 subclasses of breast cancer, and 2 non-cancer breast epithelial cell lines. Tumor cell lysate-binding was observed in 28% of the hybridoma clones. The lysate-binding clones were further evaluated with whole cell imaging, flow cytometry, and Western blotting. Approximately 10% of the tumor-binding clones were found to bind whole tumor cells with unique binding patterns. These clones were also found to bind to the patient's own tumor. Thus, we have identified several tumor-specific autoantibodies from breast cancer patients. Successful outcome of these experiments demonstrate the feasibility of rapidly generating human monoclonal Abs that have a great potential for tumor target discovery and their use in cancer therapy and diagnosis. The innovative aspect of this strategy is the exploitation of the cancer patient's own immune repertoire for generating therapeutic Abs. This is in contrast to most of the currently available therapeutic Abs for clinical use, which are derived from chimerization and humanization of rodent Abs. No currently available antibody is developed through the selective and regulatory processes of the human immune system.

Citation Format: Girja S. Shukla, Stephanie C. Pero, Yu-Jing Sun, Chelsea Carman, David N. Krag. Generation of tumor-specific antibodies from sentinel lymph nodes of breast cancer patients using hybridoma technology. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4736. doi:10.1158/1538-7445.AM2013-4736

Intrusive thoughts and avoidance in breast cancer: Individual differences and association with psychological distress

Abstract Eighty-five women with newly diagnosed breast cancer were classified on the basis of high and low levels of cancer-related intrusive thoughts and avoidance at diagnosis, and their psychological adjustment was studied prospectively at 3 and 6 months post diagnosis. Patients who initially reported high levels of both intrusive thoughts and avoidance and those who reported high levels of intrusive thoughts but low avoidance experienced the highest levels of anxiety and depression symptoms, and continued intrusive thoughts and avoidance. Patients who were high in avoidance but low in intrusive thoughts also experienced adjustment problems, including increased intrusive thoughts, when compared with patients who were low in both types of symptoms. The findings highlight the value of considering subgroup differences in patterns of intrusion and avoidance as predictors of subsequent psychological adjustment to breast cancer.

Interaction of the non-phosphorylated peptide G7-18NATE with Grb7-SH2 domain requires phosphate for enhanced affinity and specificity

Src-homology (SH2) domains are an attractive target for the inhibition of specific signalling pathways but pose the challenge of developing a truly specific inhibitor. The G7-18NATE cyclic peptide is reported to specifically inhibit the growth factor receptor bound protein 7 (Grb7) adapter protein, implicated in the progression of several cancer types, via interactions with its SH2 domain. G7-18NATE effectively inhibits the interaction of Grb7 with ErbB3 and focal adhesion kinase in cell lysates and, with the addition of a cell permeability sequence, inhibits the growth and migration of a number of breast cancer cell lines. It is thus a promising lead in the development of therapeutics targeted to Grb7. Here we investigate the degree to which G7-18NATE is specific for the Grb7-SH2 domain compared with closely related SH2 domains including those of Grb10, Grb14, and Grb2 using surface plasmon resonance. We demonstrate that G7-18NATE binds with micromolar binding affinity to Grb7-SH2 domain (K(D)  = 4-6 μm) compared with 50-200 times lower affinity for Grb10, Grb14, and Grb2 but that this specificity depends critically on the presence of phosphate in millimolar concentrations. Other differences in buffer composition, including use of Tris or 2-(N-Morpholino)ethanesulfonic acid or varying the pH, do not impact on the interaction. This suggests that under cellular conditions, G7-18NATE binds with highest affinity to Grb7. In addition, our findings demonstrate that the basis of specificity of G7-18NATE binding to the Grb7-SH2 domain is via other than intrinsic structural features of the protein, representing an unexpected mode of molecular recognition.

Abstract 2511: Tumor cell-specific full-length human antibodies from Epstein-Barr virus-immortalized sentinel node B lymphocytes from breast cancer patients

It has been demonstrated that patients do develop autoantibodies to a solid tumor, but the level of the antibody response is too low to have significant antitumor effect. This means that there are B cell clones producing antitumor antibodies, but they are suppressed (or not activated sufficiently) by the complex immunoregulatory systems in cancer patients. When the B cell repertoire is transferred out of the human cancer patient, in vitro methods allow the selection of anti-tumor antibodies and can then allow unrestricted production of sufficient quantities for clinical use. There are a variety of options available for the in vitro generation of antibodies from human B cells that are basically based on the recombinant production following gene cloning, and on B cell immortalization, their propagation and antibody secretion in cell culture. Most popular forms of recombinant expression of antibodies are phage displayed scFv and Fab antibody libraries, which have disadvantage of loss of original heavy and light chain pairings, inability to display full antibody, and production in bacterial host cells. The antibodies produced by B cell immortalization do not suffer from these drawbacks and retain their original heavy and light chain pairings. We collected fresh sentinel nodes and breast tumor specimens from cancer patients and following B lymphocyte separation from sentinel nodes they were immortalized using Epstein-Barr virus (EBV). The antibodies secreted from the immortalized B cells were studied for binding to the tumor cells of established cell lines and to the tumor cell surface protein preparations from the same patient that the B cells were derived. Using cell-ELISA and dot blot techniques, we identified several antibodies that were found to bind intact tumor cells and to the cell surface protein preparations derived from patient's tumors. It is expected that cancer-specific antibodies identified by B cell immortalization method will be candidates for therapeutic and diagnostic applications and further studies to identify their target antigens and bioactivity will help in understanding the humoral immune response to these breast cancer antigens and their role in the cell proliferation and tumor growth. An innovative aspect of this study is the exploitation of the cancer patients’ own immune repertoire for generating therapeutic antibodies. This is in contrast to most of the currently available therapeutic antibodies for clinical use, which are derived from chimerization or humanization of rodent antibodies. Currently no commercially available mAb has been developed through the selective and regulatory processes of the human immune system. The ability to reliably and rapidly generate tumor-binding antibodies from patients’ own B cells will have broad applicability and provide a platform for developing innovative therapeutic and diagnostic reagents.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2511. doi:1538-7445.AM2012-2511

Abstract C156: GRB7 is required for triple-negative breast cancer motility, invasion, and chemoresistance

Triple-negative breast tumors lack expression of estrogen and progesterone receptors and HER2, rendering them non-responsive to the most effective targeted therapies in breast cancer. These tumors are typically more aggressive than other breast cancer subtypes and, consequently, have a poor prognosis. In a clinical trial of triple-negative breast cancer patients treated with anthracyclines and taxanes, we and others have recently determined that high levels of GRB7 are predictive of tumor recurrence (Sparano et al. J Clin Oncol 27(15s) 500). GRB7 is a cytoplasmic adaptor protein that interacts with receptor tyrosine kinases and integrins, transducing information to their downstream signaling cascades.

In this study, we have tested the hypothesis that triple-negative breast cancer cell lines are dependent on GRB7 for migration, invasion and colony formation in 3D culture. Using a highly specific peptide inhibitor (G7–18NATE), we found that the GRB7 inhibition significantly impaired each of these phenotypes in four triple-negative breast cancer cell lines: MDA-MB-468, MDA-MB-231, HCC70 and T4-2. In addition, we have tested whether GRB7 inhibition may sensitize these cell lines to the chemotherapies used in the initial clinical trial. Combination treatment with G7–18NATE and doxorubicin or docetaxel resulted in cooperative cell growth inhibition in each of the four cell lines. Co-treatment lowered the IC40 of both chemotherapeutic agents, and it proved to be synergistic in all cases (Combination Index values &lt;1)

These data implicate GRB7 as a key mediator of migration, invasion, colony growth and chemoresistance of triple-negative breast cancer cells and suggest that GRB7 itself, or GRB7-dependent pathways, may prove to be important therapeutic targets.

This work was supported in part by Susan G. Komen for the Cure (KG091136 and KG100888).

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr C156.

GRB7 is required for triple-negative breast cancer cell invasion and survival

Triple-negative breast cancer (TNBC) is a heterogeneous disease that is usually associated with poor prognosis, and frequently associated with the basal-like breast cancer gene expression profile. There are no targeted therapeutic modalities for this disease, and no useful biomarkers. High GRB7 RNA expression levels are associated with an elevated risk of recurrence in patients with operable TNBC treated with standard adjuvant anthracycline and taxane therapy. To determine whether GRB7 is involved in the pathobiology of TNBC, we evaluated the biological effects of GRB7 inhibition in a panel of triple-negative cell lines-MDA-MB-468, MDA-MB-231, HCC70, and T4-2. We found GRB7 inhibition reduced cell motility and invasion of these cell lines and promoted cell death by apoptosis in 3D culture. These data suggest that GRB7 itself, or GRB7-dependent pathways, may prove to be important therapeutic targets in this disease.

Structural basis of binding by cyclic nonphosphorylated peptide antagonists of Grb7 implicated in breast cancer progression

Growth-receptor-bound protein (Grb)7 is an adapter protein aberrantly overexpressed, along with the erbB-2 receptor in breast cancer and in other cancers. Normally recruited to focal adhesions with a role in cell migration, it is associated with erbB-2 in cancer cells and is found to exacerbate cancer progression via stimulation of cell migration and proliferation. The G7-18NATE peptide (sequence: WFEGYDNTFPC cyclized via a thioether bond) is a nonphosphorylated peptide that was developed for the specific inhibition of Grb7 by blocking its SH2 domain. Cell-permeable versions of G7-18NATE are effective in the reduction of migration and proliferation in Grb7-overexpressing cells. It thus represents a promising starting point for the development of a therapeutic against Grb7. Here, we report the crystal structure of the G7-18NATE peptide in complex with the Grb7-SH2 domain, revealing the structural basis for its interaction. We also report further rounds of phage display that have identified G7-18NATE analogues with micromolar affinity for Grb7-SH2. These peptides retained amino acids F2, G4, and F9, as well as the YDN motif that the structural biology study showed to be the main residues in contact with the Grb7-SH2 domain. Isothermal titration calorimetry measurements reveal similar and better binding affinity of these peptides compared with G7-18NATE. Together, this study facilitates the optimization of second-generation inhibitors of Grb7.

Abstract 255: GRB7 – a novel target in triple-negative breast cancer

Triple-negative breast tumors lack expression of estrogen and progesterone receptors and HER2, rendering them non-responsive to the most effective targeted therapies in breast cancer. These tumors are typically more aggressive than other breast cancer subtypes and, consequently, have a poor prognosis. In a clinical trial of triple-negative breast cancer patients treated with anthracyclines and taxanes, we and others have recently determined that high levels of GRB7 are predictive of tumor recurrence. GRB7 is a cytoplasmic adaptor protein that interacts with receptor tyrosine kinases and integrins, transducing information to their downstream signaling cascades.

In this study, we have tested the hypothesis that triple-negative breast cancer cell lines are dependent on GRB7 for migration, invasion and colony formation in 3D culture. Using a highly specific peptide inhibitor (G7-18NATE), we found that the GRB7 inhibition significantly impaired each of these phenotypes in four triple-negative breast cancer cell lines: MDA-MB-468, MDA-MB-231, HCC70 and T4-2. In addition, we have tested whether GRB7 inhibition may sensitize these cell lines to the chemotherapies used in the initial clinical trial. Combination treatment with G7-18NATE and doxorubicin or docetaxel resulted in cooperative cell growth inhibition in each of the four cell lines. Co-treatment lowered the IC40 of both chemotherapeutic agents, and it proved to be synergistic in all cases (Combination Index values &lt;1)

These data implicate GRB7 as a key mediator of migration, invasion, colony growth and chemoresistance of triple-negative breast cancer cells and suggest that GRB7 itself, or GRB7-dependent pathways, may prove to be important targets therapeutic.

This work was supported in part by Susan G. Komen for the Cure (KG091136).

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 255. doi:10.1158/1538-7445.AM2011-255

Abstract 1769: Phage display selection of cancer cell-binding and -internalizing ligands using random peptide libraries constructed at N-terminus of P99 cephalosporinase

The cancer researchers today are focused in developing new types of cancer treatments that use drugs or other substances to identify and kill cancer cells while doing very little or no damage to normal healthy cells. It is believed that an ability to home in on cancer cells makes chemotherapy both more effective and less likely to cause side effects. One of the strategies to achieve this goal depends on developing ligands that specifically bind/internalize to cancer cells and exert therapeutic effects of their own or guide a targeted delivery of a therapeutic agent (cytotoxic drug, gene, radionuclide, or enzyme) to the tumor cells. Phage display is one example of high throughput technologies that has been successfully utilized for the generation of massive ligand libraries and their selection against specific targets. We constructed novel phage-displayed random linear dodecapeptide (X12) and cysteine-constrained random decapeptide (CX10C) libraries at N-terminal end of the Enterobacter cloacae P99 cephalosporinase molecule (P99 β-lactamase: β-lactam hydrolase, E.C. # 3.5.2.6). The peptide-β-lactamase fusions were displayed at the amino terminus of the minor coat pIII protein of M13 filamentous phage. Several cancer cell-specific binding β-lactamase-peptide fusion ligands were isolated by selecting these libraries on live BT-474 human breast cancer cells. The identified ligands shared several significant motifs, which showed their selectivity and possible binding to some common cancer cell targets. β-Lactamase is a high turnover enzyme with several available chromogenic and fluorogenic substrates. The peptide fusion to this enzyme made the post-panning steps very fast and simple. The concentrations of β-lactamase-peptide fusions in phage samples, lysates and purified fusion proteins were normalized based on the β-lactamase activity. The clone screening was also based on assaying the residual cell-bound β-lactamase activity. Some of the cancer cell binding β-lactamase-peptide fusion proteins showed cell internalization by both immunofluorescence and β-lactamase activity-based procedures. The staining with FRET-based substrate CCF4 confirmed the functional integrity of the internalized β-lactamase, and demonstrated that at least a part of the internalized enzyme conjugate could escape the endosomal degradation pathway in intact form and reacted with the substrate present in the cytoplasm. The specificity of the selected ligands was assessed by studying their binding and internalization in 11 other cancer and non-cancer cell lines. The β-lactamase fusion to peptides not only accelerates the clone screening process but can also facilitate the tracking of ligand molecules in various biological studies. The cancer-specific affinity reagents selected from these libraries have a potential for their use in targeted therapies.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1769. doi:10.1158/1538-7445.AM2011-1769

Abstract 2680: Characterization of tumor associated antigens using a recombinant expression of a patient derived breast cancer cDNA library and autologous serum using the SEREX technique

Autoantibodies to tumor proteins in patient serum may serve as biomarkers in breast cancer diagnosis or as a potential targeted therapeutic when conjugated to drugs or radiotherapies. The tumor associated antigens (TAAs) to which they bind may be of further diagnostic or prognostic value. In order to identify TAAs, a cDNA library was created from a patient breast tumor, recombinantly expressed with lambda phage in XL1-Blue cells, and tested against autologous patient serum to identify potential TAAs using a modified technique based on serological analysis of recombinant cDNA expression libraries (SEREX) that allows for much smaller quantities of source material and reduces library production time. Identified TAAs and serum autoantibody concentrations against those proteins will be presented in the context of developing a new customized therapy for patients with breast cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2680. doi:10.1158/1538-7445.AM2011-2680

Effect of occult metastases on survival in node-negative breast cancer

BACKGROUND

Retrospective and observational analyses suggest that occult lymph-node metastases are an important prognostic factor for disease recurrence or survival among patients with breast cancer. Prospective data on clinical outcomes from randomized trials according to sentinel-node involvement have been lacking.

METHODS

We randomly assigned women with breast cancer to sentinel-lymph-node biopsy plus axillary dissection or sentinel-lymph-node biopsy alone. Paraffin-embedded tissue blocks of sentinel lymph nodes obtained from patients with pathologically negative sentinel lymph nodes were centrally evaluated for occult metastases deeper in the blocks. Both routine staining and immunohistochemical staining for cytokeratin were used at two widely spaced additional tissue levels. Treating physicians were unaware of the findings, which were not used for clinical treatment decisions. The initial evaluation at participating sites was designed to detect all macrometastases larger than 2 mm in the greatest dimension.

RESULTS

Occult metastases were detected in 15.9% (95% confidence interval [CI], 14.7 to 17.1) of 3887 patients. Log-rank tests indicated a significant difference between patients in whom occult metastases were detected and those in whom no occult metastases were detected with respect to overall survival (P=0.03), disease-free survival (P=0.02), and distant-disease-free interval (P=0.04). The corresponding adjusted hazard ratios for death, any outcome event, and distant disease were 1.40 (95% CI, 1.05 to 1.86), 1.31 (95% CI, 1.07 to 1.60), and 1.30 (95% CI, 1.02 to 1.66), respectively. Five-year Kaplan-Meier estimates of overall survival among patients in whom occult metastases were detected and those without detectable metastases were 94.6% and 95.8%, respectively.

CONCLUSIONS

Occult metastases were an independent prognostic variable in patients with sentinel nodes that were negative on initial examination; however, the magnitude of the difference in outcome at 5 years was small (1.2 percentage points). These data do not indicate a clinical benefit of additional evaluation, including immunohistochemical analysis, of initially negative sentinel nodes in patients with breast cancer. (Funded by the National Cancer Institute; ClinicalTrials.gov number, NCT00003830.).

Sentinel-lymph-node resection compared with conventional axillary-lymph-node dissection in clinically node-negative patients with breast cancer: overall survival findings from the NSABP B-32 randomised phase 3 trial

BACKGROUND

Sentinel-lymph-node (SLN) surgery was designed to minimise the side-effects of lymph-node surgery but still offer outcomes equivalent to axillary-lymph-node dissection (ALND). The aims of National Surgical Adjuvant Breast and Bowel Project (NSABP) trial B-32 were to establish whether SLN resection in patients with breast cancer achieves the same survival and regional control as ALND, but with fewer side-effects.

METHODS

NSABP B-32 was a randomised controlled phase 3 trial done at 80 centres in Canada and the USA between May 1, 1999, and Feb 29, 2004. Women with invasive breast cancer were randomly assigned to either SLN resection plus ALND (group 1) or to SLN resection alone with ALND only if the SLNs were positive (group 2). Random assignment was done at the NSABP Biostatistical Center (Pittsburgh, PA, USA) with a biased coin minimisation approach in an allocation ratio of 1:1. Stratification variables were age at entry (≤ 49 years, ≥ 50 years), clinical tumour size (≤ 2·0 cm, 2·1-4·0 cm, ≥ 4·1 cm), and surgical plan (lumpectomy, mastectomy). SLN resection was done with a blue dye and radioactive tracer. Outcome analyses were done in patients who were assessed as having pathologically negative sentinel nodes and for whom follow-up data were available. The primary endpoint was overall survival. Analyses were done on an intention-to-treat basis. All deaths, irrespective of cause, were included. The mean time on study for the SLN-negative patients with follow-up information was 95·6 months (range 70·1-126·7). This study is registered with ClinicalTrials.gov, number NCT00003830.

FINDINGS

5611 women were randomly assigned to the treatment groups, 3989 had pathologically negative SLN. 309 deaths were reported in the 3986 SLN-negative patients with follow-up information: 140 of 1975 patients in group 1 and 169 of 2011 in group 2. Log-rank comparison of overall survival in groups 1 and 2 yielded an unadjusted hazard ratio (HR) of 1·20 (95% CI 0·96-1·50; p=0·12). 8-year Kaplan-Meier estimates for overall survival were 91·8% (95% CI 90·4-93·3) in group 1 and 90·3% (88·8-91·8) in group 2. Treatment comparisons for disease-free survival yielded an unadjusted HR of 1·05 (95% CI 0·90-1·22; p=0·54). 8-year Kaplan-Meier estimates for disease-free survival were 82·4% (80·5-84·4) in group 1 and 81·5% (79·6-83·4) in group 2. There were eight regional-node recurrences as first events in group 1 and 14 in group 2 (p=0·22). Patients are continuing follow-up for longer-term assessment of survival and regional control. The most common adverse events were allergic reactions, mostly related to the administration of the blue dye.

INTERPRETATION

Overall survival, disease-free survival, and regional control were statistically equivalent between groups. When the SLN is negative, SLN surgery alone with no further ALND is an appropriate, safe, and effective therapy for breast cancer patients with clinically negative lymph nodes.

FUNDING

US Public Health Service, National Cancer Institute, and Department of Health and Human Services.

Novel beta-lactamase-random peptide fusion libraries for phage display selection of cancer cell-targeting agents suitable for enzyme prodrug therapy

Novel phage-displayed random linear dodecapeptide (X(12)) and cysteine-constrained decapeptide (CX(10)C) libraries constructed in fusion to the amino-terminus of P99 beta-lactamase molecules were used for identifying beta-lactamase-linked cancer cell-specific ligands. The size and quality of both libraries were comparable to the standards of other reported phage display systems. Using the single-round panning method based on phage DNA recovery, we identified several beta-lactamase fusion peptides that specifically bind to live human breast cancer MDA-MB-361 cells. The beta-lactamase fusion to the peptides helped in conducting the enzyme activity-based clone normalization and cell-binding screening in a very time- and cost-efficient manner. The methods were suitable for 96-well readout as well as microscopic imaging. The success of the biopanning was indicated by the presence of approximately 40% cancer cell-specific clones among recovered phages. One of the binding clones appeared multiple times. The cancer cell-binding fusion peptides also shared several significant motifs. This opens a new way of preparing and selecting phage display libraries. The cancer cell-specific beta-lactamase-linked affinity reagents selected from these libraries can be used for any application that requires a reporter for tracking the ligand molecules. Furthermore, these affinity reagents have also a potential for their direct use in the targeted enzyme prodrug therapy of cancer.

Patient-reported outcomes in sentinel node-negative adjuvant breast cancer patients receiving sentinel-node biopsy or axillary dissection: National Surgical Adjuvant Breast and Bowel Project phase III protocol B-32

PURPOSE

Sentinel lymph node resection (SNR) may reduce morbidity while providing the same clinical utility as conventional axillary dissection (AD). National Surgical Adjuvant Breast and Bowel Project (NSABP) B-32 is a randomized phase III trial comparing SNR immediately followed by AD (SNAD) to SNR and subsequent AD if SN is positive. We report the definitive patient-reported outcomes (PRO) comparisons.

PATIENTS AND METHODS

Eligible patients had clinically node-negative, operable invasive breast cancer. The PRO substudy included all SN-negative participants enrolled May 2001 to February 2004 at community institutions in the United States (n = 749; 78% age > or = 50; 87% clinical tumor size < or = 2.0 cm; 84% lumpectomy; 87% white). They completed questionnaires presurgery, 1 and 2 to 3 weeks postoperatively, and every 6 months through year 3. Arm symptoms, arm use avoidance, activity limitations, and quality of life (QOL) were compared with intent-to-treat two-sample t-tests and repeated measures analyses.

RESULTS

Arm symptoms were significantly more bothersome for SNAD compared with SNR patients at 6 months (mean, 4.8 v 3.0; P < .001) and at 12 months (3.6 v 2.5; P = .006). Longitudinally, SNAD patients were more likely to experience ipsilateral arm and breast symptoms, restricted work and social activity, and impaired QOL (P < or = .002 all items). From 12 to 36 months, fewer than 15% of either SNAD or SNR patients reported moderate or greater severity of any given symptom or activity limitation.

CONCLUSION

Arm morbidity was greater with SNAD than with SNR. Despite considerable fears about complications from AD for breast cancer, this study demonstrates that initial problems with either surgery resolve over time.

Morbidity results from the NSABP B-32 trial comparing sentinel lymph node dissection versus axillary dissection

BACKGROUND AND OBJECTIVES

Three year post-surgical morbidity levels were compared between patients with negative sentinel lymph node dissection alone (SLND) and those with negative sentinel node dissection and negative axillary lymph node dissection (ALND) in the NSABP B-32 trial.

METHODS

A total of 1,975 ALND and 2,008 SLND node negative breast cancer patients had shoulder range of motion and arm volumes assessed along with self reports of arm tingling and numbness. Relative shoulder abduction deficits and relative arm volume differences between ipsilateral and contralateral arms were calculated.

RESULTS

Shoulder abduction deficits >or=10% peaked at 1 week for the ALND (75%) and SLND (41%) groups. Arm volume differences >or=10% at 36 months were evident for the ALND (14%) and SLND (8%) groups. Numbness and tingling peaked at 6 months for the ALND (49%, 23%) and SLND (15%, 10%) groups. Logistic regression correlates of residual morbidity included treatment group, age, handedness, tumor size, systemic chemotherapy, and radiation to the axilla.

CONCLUSIONS

Although residual morbidity for both treatment groups was evident, the results of the NSABP B-32 study indicate the superiority of the SLND compared to the ALND treatment approach relative to post-surgical morbidity outcomes over a 3-year follow-up period.

Phage-displayed combinatorial peptide libraries in fusion to beta-lactamase as reporter for an accelerated clone screening: Potential uses of selected enzyme-linked affinity reagents in downstream applications

Phage-display selection of combinatorial libraries is a powerful technique for identifying binding ligands against desired targets. Evaluation of target binding capacity of multiple clones recovered from phage display selection to a specific target is laborious, time-consuming, and a rate-limiting step. We constructed phage-display combinatorial peptide libraries in fusion with a beta-lactamase enzyme, which acts as a reporter. Linear dodecapeptide and cysteine-constrained decapeptide libraries were created at the amino-terminus of the Enterobacter cloacae P99 cephalosporinase molecule (P99 beta-lactamase). The overall and positional diversity of amino acids in both libraries was similar to other phage-display systems. The libraries were selected against the extracellular domain of ErbB2 receptor (ErbB2(ECD)). The target-selected clones were already conjugated to an enzyme reporter, therefore, did not require subcloning or any other post-panning modifications. We used beta-lactamase enzyme activity-based assays for sample normalizations and clone binding evaluation. Clones were identified that bound to purified ErbB2(ECD) and ErbB2-overexpressing cell-lines. The peptide sequences of the selected binding clones shared significant motifs with several rationally designed peptide mimetics and phage-display derived peptides that have been reported to bind ErbB2(ECD). beta-Lactamase fusion to peptides saved time and resources otherwise required by the phage-ELISA of a typical phage display screening protocol. The beta-lactamase enzyme assay protocols is a one-step process that does not require secondary proteins, several steps of lengthy incubations, or washings and can be finished in a few minutes instead of hours. The clone screening protocol can be adopted for a high throughput platform. Target-specific beta-lactamase-linked affinity reagents selected by this procedure can be produced in bulk, purified, and used, without any modification, for a variety of downstream applications, including targeted prodrug therapy.

Abstract LB-267: GRB7: A novel target in basal breast cancer

Basal breast cancers lack expression of estrogen and progesterone receptors and HER2, rendering them non-responsive to the most commonly used targeted therapies in breast cancer. These tumors are typically more aggressive, more locally invasive and more likely to metastasize to the brain than other breast cancer subtypes and, consequently, have a poor prognosis. GRB7 is a cytoplasmic adaptor protein that interacts with receptor tyrosine kinases, relaying information to their downstream signaling cascades. It also plays a role in integrin signaling and cell migration by binding focal adhesion kinase (FAK) and ephrin receptors. It is a part of the HER2 amplicon and is frequently overexpressed in HER2-amplified breast tumors. Breast tumors in which HER2 and GRB7 are both co-amplified and co-overexpressed have a poor prognosis.

We and others have recently determined that high levels of GRB7 are associated with recurrence in women with triple-negative breast cancer treated with anthracyclines (Sparano et al. J Clin Oncol 27(15s) 500). In this study, we have tested the hypothesis that triple-negative breast cancer cell lines are dependent on GRB7 for proliferation, migration and invasion. We have utilized a highly specific cell-penetrating peptide inhibitor of GRB7 (G7-18NATE) and tested its effects on a panel of 5 basal breast cancer cell lines in a series of culture assays: monolayer wound healing assays (motility on 2D substrates), transwell invasion assays (in vitro invasiveness) and 3D Matrigel cultures (morphogenesis in 3D environment). In all cases evaluated, the Grb7 inhibitory peptide impaired the proliferation, migration and invasion of these cell lines, even though these cells express low levels of GRB7 compared to HER2-amplified cell lines.

These data implicate GRB7 as a key mediator of several important phenotypes of basal breast cancer cells and suggest that GRB7 itself, or GRB7-dependent pathways, may prove to be important targets for the development of specific therapies for this disease.

This work was supported in part by Susan G. Komen for the Cure (KG091136).

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-267.

Abstract 720: Phage display selection of ligands against extracellular domain of ErbB2 receptor using novel β-lactamase-random peptide fusion libraries

There are now unprecedented opportunities for increased throughput to develop novel molecules that target cancer. Phage display is one example of a high throughput method of generating massive libraries of molecules that have different structural properties. We constructed novel phage-display random peptide libraries in fusion to β-lactamase (β-lactam hydrolase, E.C. # 3.5.2.6) enzyme as a reporter. The linear dodecapeptide (X12) and cysteine-constrained decapeptide (CX10C) libraries were created at the N-terminal end of the Enterobacter cloacae P99 cephalosporinase molecule (P99 β-lactamase), between the signal peptide and the enzyme protein. Peptide-β-lactamase fusions were displayed at the amino terminus of the minor coat pIII protein of filamentous (M13) phage. The overall representations of different amino acids in the random regions of both libraries were very good. The amino acid diversity at each position in the random regions of both the libraries was also good. The libraries were selected against the extracellular domain of ErbB2 receptor (ErbB2-ECD). The target-selected clones were already conjugated to an enzyme reporter, therefore, did not require subcloning or any other post-panning modifications. β-Lactamase is known for high turnover of its enzyme activity with several commercially available chromogenic and fluorogenic substrates. This helped us to develop a very sensitive and efficient assay for measuring concentrations and target-binding of β-lactamase-peptide fusion proteins in their both phage-displayed and soluble forms. The β-lactamase enzyme assay protocol is a one-step process and unlike a typical phage-ELISA it does not require secondary proteins, several steps of lengthy incubations, or washings and can be finished in a few minutes instead of hours. The clone screening protocol can be adopted for a high throughput platform. The identities of peptide-β-lactase fusion clones that bound to purified ErbB2-ECD and ErbB2-overexpressing MCF-7/ErbB2 and SK-BR-3 cell lines were determined by DNA sequencing of the random inserts. The peptide sequences of the selected binding clones were found to share significant motifs with several rationally designed peptide mimetics and phage-display derived peptides that have been reported to bind ErbB2-ECD. Target-specific β-lactamase-linked affinity reagents selected by this procedure can be produced in bulk and purified. The synthesis and successful use of cephalosporin prodrugs of mechanistically diverse anticancer agents, such as doxorubicin, taxol, platinum complexes, phenylenediamine mustard, and vinblastine have been reported in experimental studies. Using an appropriate β-lactam-substrate, the cancer cell-specific ligands selected from these libraries can be used directly for the targeted enzyme prodrug therapy and/or in vivo imaging of cancers.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 720.

Identification of single chain antibodies to breast cancer stem cells using phage display

Recent evidence suggests that most malignancies are driven by "cancer stem cells" sharing the signature characteristics of adult stem cells: the ability to self renew and to differentiate. Furthermore these cells are thought to be quiescent, infrequently dividing cells with a natural resistance to chemotherapeutic agents. These studies theorize that therapies, which effectively treat the majority of tumor cells but 'miss' the stem cell population, will fail, while therapies directed at stern cells can potentially eradicate tumors. In breast cancer, researchers have isolated 'breast cancer stem cells' capable of recreating the tumor in vivo and in vitro. Generated new tumors contained both additional numbers of cancer stem cells and diverse mixed populations of cells present in the initial tumor, supporting the intriguing self-renewal and differentiation characteristics. In the present study, an antibody phage library has been used to search for phage displayed-single chain antibodies (scFv) with selective affinity to specific targets on breast cancer stem cells. We demonstrate evidence of two clones binding specifically to a cancer stem cell population isolated from the SUMl59 breast cancer cell line. These clones had selective affinity for cancer stem cells and they were able to select cancer stem cells among a large population of non-stem cancer cells in paraffin-embedded sections. The applicability of these clones to paraffin sections and frozen tissue specimens made them good candidates to be used as diagnostic and prognostic markers in breast cancer patient samples taking into consideration the cancer stern cell concept in tumor biology.

Cancer cell-specific internalizing ligands from phage displayed beta-lactamase-peptide fusion libraries

The present study was focused on identifying cancer cell-specific internalizing ligands using a new kind of phage display library in which the linear or cysteine-constrained random peptides were at amino-terminus fusion to catalytically active P99 beta-lactamase molecules. The size and quality of libraries were comparable to other reported phage display systems. Several cancer cell-specific binding and internalizing beta-lactamase-peptide fusion ligands were isolated by selecting these libraries on the live BT-474 human breast cancer cells. The identified ligands shared several significant motifs, which showed their selectivity and possible binding to some common cancer cell targets. The beta-lactamase fusion made the whole process of clone screening efficient and simple. The ligands selected from such libraries do not require peptide synthesis and modifications, and can be used directly for applications that require ligand tracking. In addition, the selected beta-lactamase-peptide ligands have a potential for their direct use in targeted enzyme prodrug therapy. The cancer-specific peptides can also be adopted for other kinds of targeted delivery protocols requiring cell-specific affinity reagents. This is first report on the selection of cell-internalized enzyme conjugates using phage display technology, which opens the possibility for new fusion libraries with other relevant enzymes.

Developing bifunctional beta-lactamase molecules with built-in target-recognizing module for prodrug therapy: identification of Enterobacter Cloacae P99 cephalosporinase loops suitable for randomization and phage-display selection

This study was focused on developing catalytically active beta-lactamase enzyme molecules that have target-recognizing sites built within their scaffold. Using phage-display approach, nine libraries were constructed by inserting the randomized linear or cysteine-constrained heptapeptides in the five different loops on the outer surface of P99 beta-lactamase molecule. The pIII signal peptide of Sec-pathway was employed for a periplasmic translocation of the beta-lactamase fusion protein, which we found more efficient than the DsbA signal peptide of SRP-pathway. The randomized heptapeptide loops replaced native amino acids between positions (34)Y-(37)K, (238)M-(246)A, (275)N-(280)A, (305)A-(311)S, or (329)I-(334)I of the P99 beta-lactamase molecules for generating the loop-1 to -5 libraries, respectively. The diversity of each loop library was judged by counting the primary and beta-lactamase-active clones. The linear peptide inserts in the loop-2 library showed the maximum number of the beta-lactamase-active clones, followed by the loop-5, loop-3, and loop-4. The insertion of the cysteine-constrained loops exhibited a dramatic loss of the enzyme-active beta-lactamase clones. The complexity of the loop-2 linear library, as determined by the frequency and diversity of amino acid distributions in the randomized region, appears consistent with the standards of other types of phage display library systems. The selection of the loop-2 linear library on streptavidin protein as a test target identified several beta-lactamase clones that specifically bound to streptavidin. In conclusion, this study identified the suitability of the loop-2 of P99 beta-lactamase for constructing a phage-display library of the beta-lactamase enzyme-active molecules that can be selected against a target. This is an enabling step in our long-term goal of developing bifunctional beta-lactamase molecules against cancer-specific targets for enzyme prodrug therapy of cancer.

Surgeon training, protocol compliance, and technical outcomes from breast cancer sentinel lymph node randomized trial

BACKGROUND

The National Surgical Adjuvant Breast and Bowel Project B-32 trial was designed to determine whether sentinel lymph node resection can achieve the same therapeutic outcomes as axillary lymph node resection but with fewer side effects and is one of the most carefully controlled and monitored randomized trials in the field of surgical oncology. We evaluated the relationship of surgeon trial preparation, protocol compliance audit, and technical outcomes.

METHODS

Preparation for this trial included a protocol manual, a site visit with key participants, an intraoperative session with the surgeon, and prerandomization documentation of protocol compliance. Training categories included surgeons who submitted material on five prerandomization surgeries and were trained by a core trainer (category 1) or by a site trainer (category 2). An expedited group (category 3) included surgeons with extensive experience who submitted material on one prerandomization surgery. At completion of training, surgeons could accrue patients. Two hundred twenty-four surgeons enrolled 4994 patients with breast cancer and were audited for 94 specific items in the following four categories: procedural, operative note, pathology report, and data entry. The relationship of training method; protocol compliance performance audit; and the technical outcomes of the sentinel lymph node resection rate, false-negative rate, and number of sentinel lymph nodes removed was determined. All statistical tests were two-sided.

RESULTS

The overall sentinel lymph node resection success rate was 96.9% (95% confidence interval [CI] = 96.4% to 97.4%), and the overall false-negative rate was 9.5% (95% CI = 7.4% to 12.0%), with no statistical differences between training methods. Overall audit outcomes were excellent in all four categories. For all three training groups combined, a statistically significant positive association was observed between surgeons' average number of procedural errors and their false-negative rate (rho = +0.188, P = .021).

CONCLUSIONS

All three training methods resulted in uniform and high overall sentinel lymph node resection rates. Subgroup analyses identified some variation in false-negative rates that were related to audited outcome performance measures.

Quality measures for breast cancer surgery: initial validation of feasibility and assessment of variation among surgeons

OBJECTIVES

To identify and quantify surgical outcomes as possible quality measures of initial breast cancer surgery and to assess variation among surgeons.

DESIGN

Descriptive analysis of concurrently collected outcome measures.

SETTING

University hospital with a designated breast cancer center.

PATIENTS

Patients with a preoperative diagnosis of invasive breast cancer or ductal carcinoma in situ undergoing their initial cancer surgery from April 1, 2003, to March 30, 2008.

MAIN OUTCOME MEASURES

Eight measures were identified: (1) total mastectomy rate; (2) close (<1 mm) and positive margin rate following initial partial mastectomy; (3) number of operations required in breast conservation; (4) number of nodes obtained from sentinel lymph node biopsy; (5) number of nodes from axillary dissection; (6) proportion of patients with positive sentinel lymph node biopsy undergoing axillary dissection; (7) use of intraoperative lymph node assessment; and (8) time from diagnosis to surgery.

RESULTS

Nine hundred ten operations (218 for ductal carcinoma in situ, 692 for invasive breast cancer) were performed by 6 surgeons. Variation existed among surgeons in the combined close and positive margin rate, number of nodes obtained from sentinel lymph node biopsy, and use of intraoperative lymph node assessment. No significant variation was seen for the overall mastectomy rate, mean number of operations, positive margin rate alone, and number of lymph nodes from axillary dissection.

CONCLUSIONS

Quality indicators for breast cancer surgery can be identified and readily monitored. Outcome variation exists at a high-volume breast center. Further study into the causes and effects of this variation on short- and long-term patient outcomes as well as health care costs is needed.