Paired Distant Metastases Research Articles

CD103+ Tissue Resident T-Lymphocytes Accumulate in Lung Metastases and Are Correlated with Poor Prognosis in ccRCC.

Simple SummaryClear cell renal cell carcinoma (ccRCC) is a highly immunogenic tumor, with highly heterogeneous responses to immune checkpoint inhibition therapy. The role of immune cells infiltrating distant metastases and their impact on prognosis and response to immunotherapy are still unclear. To elucidate the prognostic value of immune cell subtypes, we analyzed the immune cell infiltrate in ccRCC primary tumors and paired distant metastases. We hypothesized that specific subtypes of immune cells may be involved in the control of metastases and may have an impact on the prognosis of ccRCC.Clear cell renal cell carcinoma (ccRCC) is a highly immunogenic tumor with variable responses to immune checkpoint therapy. The significance of the immune cell infiltrate in distant metastases, their association with the immune infiltrate in the primary tumors and their impact on prognosis are poorly described. We hypothesized that specific subtypes of immune cells may be involved in the control of metastases and may have an impact on the prognosis of ccRCC. We analyzed the immune microenvironment in ccRCC primary tumors with distant metastases, paired distant metastases and non-metastasized ccRCC (n = 25 each group) by immunohistochemistry. Confirmatory analyses for CD8+ and CD103+ cells were performed in a large ccRCC cohort (n = 241) using a TCGA-KIRC data set (ITGAE/CD103). High immune cell infiltration in primary ccRCC tumors was significantly correlated with the development of distant tumor metastasis (p < 0.05). A high density of CD103+ cells in ccRCC was more frequent in poorly differentiated tumors (p < 0.001). ccRCCs showed high levels of ITGAE/CD103 compared with adjacent non-neoplastic tissue. A higher density of CD103+ cells and a higher ITGAE/CD103 expression were significantly correlated with poor overall survival in ccRCC (log rank p < 0.05). Our results show a major prognostic value of the immune pattern, in particular CD103+ cell infiltration in ccRCC, and highlight the importance of the tumor immune microenvironment.

Multiomics profiling of primary lung cancers and distant metastases reveals immunosuppression as a common characteristic of tumor cells with metastatic plasticity

BackgroundMetastasis is the primary cause of cancer mortality accounting for 90% of cancer deaths. Our understanding of the molecular mechanisms driving metastasis is rudimentary.ResultsWe perform whole exome sequencing (WES), RNA sequencing, methylation microarray, and immunohistochemistry (IHC) on 8 pairs of non-small cell lung cancer (NSCLC) primary tumors and matched distant metastases. Furthermore, we analyze published WES data from 35 primary NSCLC and metastasis pairs, and transcriptomic data from 4 autopsy cases with metastatic NSCLC and one metastatic lung cancer mouse model. The majority of somatic mutations are shared between primary tumors and paired distant metastases although mutational signatures suggest different mutagenesis processes in play before and after metastatic spread. Subclonal analysis reveals evidence of monoclonal seeding in 41 of 42 patients. Pathway analysis of transcriptomic data reveals that downregulated pathways in metastases are mainly immune-related. Further deconvolution analysis reveals significantly lower infiltration of various immune cell types in metastases with the exception of CD4+ T cells and M2 macrophages. These results are in line with lower densities of immune cells and higher CD4/CD8 ratios in metastases shown by IHC. Analysis of transcriptomic data from autopsy cases and animal models confirms that immunosuppression is also present in extracranial metastases. Significantly higher somatic copy number aberration and allelic imbalance burdens are identified in metastases.ConclusionsMetastasis is a molecularly late event, and immunosuppression driven by different molecular events, including somatic copy number aberration, may be a common characteristic of tumors with metastatic plasticity.

Abstract PO-005: Spatio-temporal geographical molecular mapping of primary papillary thyroid carcinomas and paired distant metastases: Clinical relevance for monitoring and targeting tumor heterogeneity

Abstract Approximately 15% of papillary thyroid carcinomas (PTCs) develop distant metastases (DMs). Little is known about the genetic alterations that underlie the metastatic spread. Despite DMs may differ from primary tumors (Pts) at the molecular level, in most patients with metastatic PTCs genetic alterations are often exclusively assessed in Pt samples and the results correlated by means of statistical analyses with a known deleterious prognostic parameter as it is the presence or not of DMs. The involvement of intratumor genetic heterogeneity (ITGH) or clonal status of actionable driver events in DMs of PTCs nowadays is still puzzling. Dynamic changes in mutation distribution through space and time have not been in deep characterized. So far no one has performed a geographical multiregional mapping of paired primary PTCs and DMs using genetic alteration profiling at different time points or different evolutionary stages In the attempt to shed some light in the complex aforementioned issues, in this study we performed a comprehensive, multiregional genotyping of 11 of the most distinctive driver genes associated with progression and aggressiveness in thyroid cancer (BRAF,HRAS,NRAS,KRAS, PIK3CA, TERTp, TP53, EIF1AX, MED12, KIT and 5’UTR of TBC1D12) in 13 cases of PTCs with matched DMs. A total of 54 tumor samples, including different areas across space and time within the Pts and the DMs were characterized by means of PCR+SSCP or DS Twelve cases (92%) were mutated in at least one of the genes screened [TERTp 69%, BRAF 54%, KRAS 23%, NRAS 23%, HRAS 15% and PIK3CA 15%, KIT 8%]. No mutations were seen at TP53, EIF1AX, MED12 and 5’UTR of TBC1D12. Among the mutated cases 67% exhibited ITGH. In 62.5% of the cases with ITGH coexisted at least 3 genes mutated. Two cases displayed four mutated genes. The genes more frequently altered in Pts with ITGH were TERTp (80%) and BRAF (80%) followed by RAS (60%). Within DMs with ITGH the genes more commonly activated were TERTp (86%) and RAS (86%) followed by BRAF (71%). In all the cases in which more than 1 area of DM, across space and time, was analyzed, the mutations at TERTp, KRAS and HRAS resulted clonal, whereas BRAF mutations tended to be subclonal. De novo mutations at DMs were seen in 7 cases. Within Pts, subclonality was as follows TERTp 30%, RAS 25%, BRAF 30%, PIK3CA 100% The number of mutational events in PTCs with DM is strikingly higher than in PTCs without DMs. Our results do not support a role for MED12, EIF1AX, TP53 and 5’UTR of TBC1D12 mutations in the aggressiveness of PTCs and development of DMs. In approximately 33% of the metastatic PTCs regional pressures, most likely exerted by the homing microenvironment at DMs, lead to the appearance of advantageous “de novo” mutations. DMs show an enrichment in TERTp, RAS, PIK3CA and KIT mutations and a decrease in BRAF mutations. The clonal status of advance stage PTCs evolves with metastatization. ITGH may reflect the early expression of an invasive phenotype in PTCs, such that PTCs with high ITGH could probably be labelled as “born to be noxious / harmful.” Citation Format: Sara Gil, José Javier Estébanez, Noa Féas, Joaquín Fra, Ginesa María Garcia-Rostán. Spatio-temporal geographical molecular mapping of primary papillary thyroid carcinomas and paired distant metastases: Clinical relevance for monitoring and targeting tumor heterogeneity [abstract]. In: Proceedings of the AACR Virtual Special Conference on Tumor Heterogeneity: From Single Cells to Clinical Impact; 2020 Sep 17-18. Philadelphia (PA): AACR; Cancer Res 2020;80(21 Suppl):Abstract nr PO-005.

Frequency of discordance in programmed death-ligand 1 (PD-L1) expression between primary tumors and paired distant metastases in advanced cancers: a systematic review and meta-analysis

Background: To determine the frequency of discordance in programmed death-ligand 1(PD-L1) expression between primary tumors and paired distant metastases in advanced cancers.Methods: We searched MEDLINE and EMBASE for eligible studies and assessed their methodologic quality using QUADAS-2 tool. We estimated the discordant rates (positive to negative or vice versa) of PD-L1 expression in primary tumors and paired distant metastases using logistic-normal random effects model. We performed subgroup analyses based on the PD-L1 status of primary tumors (positive or negative), location of primary tumors (lung or others) and distant metastases (central nervous system or others), timing of distant metastases (synchronous or metachronous), positivity thresholds of PD-L1 expression (1% or 5%) and types of antibody clones used (E1L3N or SP142).Results: Thirteen eligible studies including 451 cases were identified. The included studies were judged to have low to unclear risk of bias. The pooled estimate of discordant rates in PD-L1 expression was 31% (95% CI= 19–47%), with high heterogeneity across the studies (I2 = 75%). There was no significant effect modification in the discordant rates according to the predefined subgroups.Conclusion: Approximately one-third of advanced cancer cases have discordance in PD-L1 expression between primary tumors and paired distant metastases. A more liberal testing of PD-L1 expression in both primary and metastatic tumors is recommended in order to identify patients who may benefit from immune checkpoint blockade treatment. Further research exploring the mechanisms and its impact are warranted.

Abstract 2741: Comprehensive molecular profiling of primary tumors and paired distant metastases in non-small cell lung cancer

Abstract Despite complete resection, many non-small cell lung cancer (NSCLC) patients still develop and succumb to distant metastases, which is a major cause of cancer-related death worldwide. However, our understanding of the molecular mechanisms driving metastasis is rudimentary. We performed whole exome sequencing, RNA sequencing (RNA-seq), methylation microarray, and immunohistochemistry using multiple immune markers on 8 pairs of NSCLC primary tumors and matched distant metastases including 7 metachronous brain and 1 synchronous liver metastases. On average, 60% of all somatic mutations (22% to 90%) and 86% of canonical cancer gene mutations were shared between primary tumors and paired distant metastases. Metastases also resembled paired primary tumors closely in regard to their mutational spectrum, copy number aberrations, allelic imbalance, and methylation profiles. Genomic aberrations unique to metastases were rather patient-specific than commonly observed across multiple patients. Of particular interest, subclonal architecture analysis suggested that monoclonal metastatic seeding is a prevalent mode of metastasis in NSCLC. We validated these findings in a large published dataset consisting of 38 pairs of primary lung tumors and matched distant metastases. RNA-seq showed gene expression profiles in metastases were similar to those of paired primary tumors. Metastases commonly up-regulated metabolism-associated pathways and down-regulated immune-related pathways, consistent with the immunohistochemical staining data for CD3, CD4, CD8, CD20, CD68, PD1, and PD-L1. Our data suggest that distant metastasis is a late event during carcinogenesis and that a majority of genomic and epigenetic aberrations occur before metastatic outgrowth. While molecular mechanisms underlying postsurgical distant metastasis seem to be variable among NSCLC patients, immune suppression may be a common characteristic of cancer cells with metastatic plasticity. Citation Format: Won-Chul Lee, Daniel Gomez, Jianhua Zhang, Alexandre Reuben, Ali Jalali, Whijae Roh, Chia Chin Wu, Wei Lu, Chi-Wan Chow, Junya Fujimoto, Mara Antonoff, Cesar Moran, Erik Sulman, Ganesh Rao, Stephen Swisher, John Heymach, Ignacio I. Wistuba, Andrew Futreal, Jianjun Zhang. Comprehensive molecular profiling of primary tumors and paired distant metastases in non-small cell lung 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 2741.

Discordance of epidermal growth factor receptor mutation between primary lung tumor and paired distant metastases in non-small cell lung cancer: A systematic review and meta-analysis

PurposeTo evaluate the rate of discordance of epidermal growth factor receptor (EGFR) mutation between primary lung tumor and paired distant metastases in non-small-cell lung cancer (NSCLC).MethodsWe performed a meta-analysis of 17 studies (518 cases) assessing discordance rates of EGFR mutation in primary tumors and paired distant metastases. We performed subgroup analyses based on EGFR mutation status in primary tumor (mutant or wildtype), site of distant metastasis (bone, central nervous system (CNS) or lung/ pleural), methods of testing (direct sequencing or allele-specific testing) and timing of metastasis (synchronous or metachronous).ResultsThe overall discordance rate in EGFR mutation was low at 10.36% (95% CI = 4.23% to 18.79%) and varied widely between studies (I2 = 83.18%). The EGFR discordance rate was statistically significantly higher in bone metastases (45.49%, 95% CI = 14.13 to 79.02) than CNS (17.26%, 95% CI = 7.64 to 29.74; P = 0.002) and lung/ pleural metastases (8.17%, 95% CI = 3.35 to 14.85; P < 0.001). Subgroup analyses did not demonstrate any significant effect modification on the discordance rates by the EGFR mutation status in primary lung tumor, methods of testing and timing of metastasis.ConclusionThe overall discordance rate in EGFR mutation between primary lung tumor and paired distant metastases in NSCLC is low, although higher discordance rates were observed in bone metastases compared with CNS and lung/pleural metastases. Future studies assessing the impact of EGFR mutation discordance on treatment outcomes are required.

Expression profiles of VEGF-A, VEGF-D and VEGFR1 are higher in distant metastases than in matched primary high grade epithelial ovarian cancer

BackgroundIn many malignancies including ovarian cancer, different angiogenic factors have been related to poor prognosis. However, data on their relations to each other or importance as a prognostic factor in ovarian cancer is missing. Therefore, we investigated the expressions of VEGF-A, VEGF-C, and VEGF-D, and the receptors VEGFR1, VEGFR2, and VEGFR3 in patients with malignant epithelial ovarian neoplasms. We further compared expression levels between primary tumors and related distant omental metastases.MethodsThis study included 86 patients with malignant ovarian epithelial tumors and 16 related distant metastases. Angiogenic factor expression was evaluated using immunohistochemistry (n = 102) and qRT-PCR (n = 29).ResultsCompared to primary high grade serous ovarian tumors, the related omental metastases showed higher expressions of VEGF-A (p = 0.022), VEGF-D (p = 0.010), and VEGFR1 (p = 0.046). In univariate survival analysis, low epithelial expression of VEGF-A in primary tumors was associated with poor prognosis (p = 0.024), and short progression-free survival was associated with high VEGF-C (p = 0.034) and low VEGFR3 (p = 0.002). The relative expressions of VEGF-D, VEGFR1, VEGFR2, and VEGFR3 mRNA determined by qRT-PCR analyses were significantly correlated with the immunohistochemically detected levels of these proteins in primary high grade serous ovarian cancer and metastases (p = 0.004, p = 0.009, p = 0.015, and p = 0.018, respectively).ConclusionsThe expressions of VEGF receptors and their ligands significantly differed between malignant ovarian tumors and paired distant metastases. VEGF-A, VEGF-D, and VEGFR1 protein expressions seem to be higher in distant metastases than in the primary high grade serous ovarian cancer lesions.

Frequency of discordance in programmed death ligand 1 (PD-L1) expression between primary tumors and paired distant metastases in advanced cancers: A systematic review and meta-analysis.

e14290 Background: Randomized trials have demonstrated that PD-L1 expression in tumor cells predicts for response to PD-1 or PD-L1 checkpoint inhibitors in advanced cancers. However, the frequency of discordance in PD-L1 expression between primary tumors and paired distant metastases is currently unclear. We aimed to determine the discordance rate of PD-L1 expression between primary tumor and paired distant metastases in advanced cancers. Methods: We searched MEDLINE and EMBASE for eligible studies. We noted the discordance rate (positive-to-negative or vice versa) and performed subgroup analyses based on the PD-L1 expression in primary tumor, locations of primary tumor and distant metastases, positivity thresholds and type of antibody used for testing. We used QUADAS-2 tool to assess the methodologic quality of the included studies. We performed the meta-analysis using the logistic-normal random effects model. Results: We identified 11 eligible studies including 351 cases of lung, colorectal, breast and ovarian cancers. Nine studies were judged to have low risk of bias in their methodological quality. The overall discordance rate in PD-L1 expression between primary tumor and paired distant metastases was 28% (95% confidence interval (CI) = 18-41) with significant heterogeneity among the studies (chi-square test P-value &lt; 0.0001). There was no statistically significant differences in discordance rates between the subgroups: PD-L1-positive (40%, 95% CI = 21-63) vs PD-L1-negative primary tumors (21%, 95% CI = 12-34), lung primary (31%, 95% CI = 14-55) vs colorectal/ breast/ ovarian primary (27%, 95% CI = 19-37), central nervous system metastases (22%, 95% CI = 8-47) vs liver/ lung/ pleural/ peritoneum metastases (34%, 95% CI = 24-46); 1% (23%, 95% CI 16-33) vs 5% positivity threshold (33%, 95% CI 11-68); E1L3N (42%, 95% CI 10-82) vs SP142 antibody (27%, 95% CI 20-36). Conclusions: The discordance in PD-L1 expression between primary tumors and paired distant metastases is close to 30%, which could potentially affect response to immunotherapy. Further works exploring the mechanisms and impact of this discordance are warranted.

Frequent discordance in PD-1 and PD-L1 expression between primary breast tumors and their matched distant metastases

Programmed death-1 (PD-1) is an immune checkpoint that is able to inhibit the immune system by binding to its ligand programmed death-ligand 1 (PD-L1). In many cancer types, among which breast cancer, prognostic and/or predictive values have been suggested for both PD-1 and PD-L1. Previous research has demonstrated discrepancies in PD-L1 expression between primary breast tumors and distant metastases, however data so far have been scarce. We therefore evaluated immunohistochemical expression levels of PD-1 and PD-L1 in primary breast tumors and their paired distant metastases, and evaluated prognostic values. Tissue microarrays from formalin-fixed paraffin-embedded resection specimens of primary breast cancers and their matched distant metastases were immunohistochemically stained for PD-1 and PD-L1. PD-1 was available in both primary tumor and metastasis in 82 patients, and PD-L1 in 49 patients. PD-1 was discrepant between primary tumor and metastasis in half of the patients (50%), PD-L1 on tumor cells was discrepant in 28.5%, and PD-L1 on immune cells in 40.8% of the patients. In primary tumors there was a correlation between PD-1 positivity and a higher tumor grade, and between immune PD-L1 and ER negativity. In survival analyses, a significantly better overall survival was observed for patients with PD-L1 negative primary breast tumors that developed PD-L1 positive distant metastases (HR 3.013, CI 1.201–7.561, p = 0.019). To conclude, PD-1 and tumor and immune PD-L1 seem to be discordantly expressed between primary tumors and their matched distant metastases in about one-third to a half of the breast cancer patients. Further, gained expression of PD-L1 in metastases seems to indicate better survival. This illustrates the need of reassessing PD-1 and PD-L1 expression on biopsies of distant metastases to optimize the usefulness of these biomarkers.

Comprehensive molecular and immune profiling of non-small cell lung cancer and matched distant metastases to suggest distinct molecular mechanisms underlying metastasis.

8541 Background: Despite complete resection, many non-small cell lung cancer (NSCLC) patients still develop and succumb to distant metastases. Previous studies suggested distant metastasis may be due to genomic evolution and/or suppressed immune surveillance. However, the relationship between specific genomic alterations and immune surveillance has not been systemically studied. Methods: We performed whole exome sequencing, RNA-Seq, methylation microarray, immunohistochemistry using multiple immune markers, and T cell receptor sequencing on 7 pairs of NSCLC primary tumors and matched metastases including 6 metachronous brain and 1 synchronous liver metastases. Results: On average, 84% of all somatic mutations (54% to 97%) and all 28 canonical cancer gene mutations were shared between primary tumors and paired distant metastases. Metastases also resembled paired primary tumors closely in regard to somatic copy number aberration profiles, methylation profiles. Subclonal analysis showed almost identical clonal architectures in 4 of 7 pairs of primary tumor and metastasis comparable to the similarity observed between different regions within the same tumors. The other 3 pairs, however, displayed clear evidence of clonal evolution. We validated these findings in a published dataset consisting of 38 pairs of primary NSCLC tumors and matched distant metastases. The RNA-Seq data showed that 25 of the top 35 significantly down-regulated signaling pathways in metastases relative to primary tumors were related to immune activation, which was validated in an independent cohort of 41 primary NSCLC tumors and distant metastases using NanoString’s PanCancer Immune Profiling Panel. Conclusions: Our data suggest that molecular mechanisms underlying postsurgical distant metastasis may be variable among NSCLC patients. While genomic evolution may play a role in development of metastasis in some patients, distant metastasis may be early event during carcinogenesis without further genomic evolution in a substantial proportion of NSCLC patients. Furthermore, immune suppression may be a characteristic of cancer cells of metastatic capacity.

Abstract 156: Integrated exome and transcriptome sequencing of primary lung cancers and paired distant metastases

Abstract Background: The precise molecular mechanisms underlying metastasis of nonsmall cell lung cancers (NSCLC) are largely unknown. Two recent studies comparing genomic landscapes of primary NSCLC tumors and paired brain metastases suggested branched evolution, where all metastatic and primary tumors shared a common ancestor yet continued to evolve independently. The integrated genomic and transcriptomic profiles of primary NSCLC and metastases have not been studied in any details. Methods: We performed whole exome sequencing (WES) and RNA sequencing (RNA-seq) of surgically resected primary tumors and paired distant metastases from 7 patients with NSCLC. Results: Totally, 6,945 somatic mutations, including 1,702 non-silent (stop-gain, stop-loss, frameshift, splicing site and nonsynonymous) mutations were identified by WES. Metastases trended to have larger mutation burdens compared to paired primary tumors, although the difference was not statistically different (average 595 mutations per tumor in primary tumors versus 852 mutations per tumor in metastases, respectively, p = 0.54). On average, 51% of all mutations (24% to 93%) were shared between primary tumors and metastases. We identified 14 canonical cancer gene mutations in this cohort of patients, defined as mutations that lead to amino acid changes identical to those found previously in cancer genes or disrupting mutations in tumor suppressor genes, all of which were shared between primary tumors and paired distant metastases. In addition, metastases resembled paired primary NSCLC tumors closely in regard to somatic copy number aberration profiles and mutation signatures. Pathway analysis from RNA-seq data demonstrated that 25 of the 35 signal transduction pathways that were significantly down regulated in metastases relative to primary NSCLC tumors were related to immune activation. Validation study with a larger patient cohort is in progress. Conclusions: Although branched evolution is a common phenomenon during metastasis of NSCLC, majority of canonical cancer gene mutations are probably early molecular events likely acquired before metastasis initiates. Mutation mechanism may be determined early during carcinogenesis and preserved during cancer evolution even at the metastatic sites. Immune suppression may be one characteristic feature of cancer cells of metastatic capacity. Citation Format: Jianjun Zhang, Chia-Chin Wu, Jianhua Zhang, Junya Fujimoto, Xingzhi Song, Xizeng Mao, Huadong Sun, Sahil Seth, Rebecca Thornton, Marcus Coyle, Latasha Little, Curtis Gumbs, Carmen Behrens, Chi-Wan Chow, Erik Sulman, Ganesh Rao, Stephen Swisher, Ignacio Wistuba, John Heymach, Andrew Futreal, Daniel Gomez. Integrated exome and transcriptome sequencing of primary lung cancers and paired distant metastases. [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 156.

Identification of independent primary tumors and intrapulmonary metastases using DNA rearrangements in non-small-cell lung cancer.

Distinguishing independent primary tumors from intrapulmonary metastases in non-small-cell carcinoma remains a clinical dilemma with significant clinical implications. Using next-generation DNA sequencing, we developed a chromosomal rearrangement-based approach to differentiate multiple primary tumors from metastasis. Tumor specimens from patients with known independent primary tumors and metastatic lesions were used for lineage test development, which was then applied to multifocal tumors. Laser capture microdissection was performed separately for each tumor. Genomic DNA was isolated using direct in situ whole-genome amplification methodology, and next-generation sequencing was performed using an Illumina mate-pair library protocol. Sequence reads were mapped to the human genome, and primers spanning the fusion junctions were used for validation polymerase chain reaction. A total of 41 tumor samples were sequenced (33 adenocarcinomas [ADs] and eight squamous cell carcinomas [SQCCs]), with a range of three to 276 breakpoints per tumor identified. Lung tumors predicted to be independent primary tumors based on different histologic subtype did not share any genomic rearrangements. In patients with lung primary tumors and paired distant metastases, shared rearrangements were identified in all tumor pairs, emphasizing the patient specificity of identified breakpoints. Multifocal AD and SQCC samples were reviewed independently by two pulmonary pathologists. Concordance between histology and genomic data occurred in the majority of samples. Discrepant tumor samples were resolved by genome sequencing. A diagnostic lineage test based on genomic rearrangements from mate-pair sequencing demonstrates promise for distinguishing independent primary from metastatic disease in lung cancer.

Heterogeneity of Bcl-2 expression in metastatic breast carcinoma

Bcl-2 is an antiapoptotic protein that promotes cell survival, but also may block proliferation. In breast cancer, bcl-2 expression correlates with favorable prognosis and estrogen receptor (ER) positivity. However, experimental data have paradoxically suggested that bcl-2 promotes chemoresistance and metastasis. A direct and comprehensive comparison of bcl-2 expression between primary breast carcinomas and paired distant metastases has not been performed. We completed rapid autopsies on 17 patients with archived primary tumors and metastatic breast carcinoma, and created single-patient tissue microarrays containing each patient's primary tumor and matched metastases. Expression of bcl-2, ER, progesterone receptor, and HER-2 in primary tumors and matched metastases were compared by immunohistochemistry. All 11 ER-positive cases showed bcl-2 labeling in the primary tumor, whereas only 3 of 6 ER-negative cases did (P=0.029). In 10 cases, bcl-2 labeling in metastases was similar to that of the primary, although 3 cases showed significant variation among metastases. In six other cases, bcl-2 labeling was lost or significantly diminished in metastases. Five of the latter cases were Luminal A (ER-positive, HER-2-negative) primaries, three of which lost hormone receptors in metastases. Only 1 of 17 cases showed an increase in bcl-2 labeling in metastases compared with the paired primary tumor. In conclusion, bcl-2 is infrequently upregulated in metastatic breast carcinoma. Instead, downregulation of bcl-2 expression may occur in the setting of hormone therapy resistance. Our findings call into question the potential utility of anti-bcl-2 therapy in metastatic breast cancer.