The expression pattern of pyruvate dehydrogenase kinases predicts prognosis and correlates with immune exhaustion in clear cell renal cell carcinoma

Renal cancer cells constitute a paradigm of tumor cells with a glycolytic reprogramming which drives metabolic alterations favouring cell survival and transformation. We studied the expression and activity of pyruvate dehydrogenase kinases (PDK1-4), key enzymes of the energy metabolism, in renal cancer cells. We analysed the expression, subcellular distribution and clinicopathological correlations of PDK1-4 by immunohistochemistry of tumor tissue microarray samples from a cohort of 96 clear cell renal cell carcinoma (ccRCC) patients. Gene expression analysis was performed on whole tumor tissue sections of a subset of ccRCC samples. PDK2 and PDK3 protein expression in tumor cells correlated with lower patient overall survival, whereas PDK1 protein expression correlated with higher patient survival. Gene expression analysis revealed molecular association of PDK2 and PDK3 expression with PI3K signalling pathway, as well as with T cell infiltration and exhausted CD8 T cells. Inhibition of PDK by dichloroacetate in human renal cancer cell lines resulted in lower cell viability, which was accompanied by an increase in pAKT. Together, our findings suggest a differential role for PDK enzymes in ccRCC progression, and highlight PDK as actionable metabolic proteins in relation with PI3K signalling and exhausted CD8 T cells in ccRCC.

New frontiers in immune checkpoint B7-H3 (CD276) research and drug development

B7-H3 (CD276), a member of the B7 family of proteins, is a key player in cancer progression. This immune checkpoint molecule is selectively expressed in both tumor cells and immune cells within the tumor microenvironment. In addition to its immune checkpoint function, B7-H3 has been linked to tumor cell proliferation, metastasis, and therapeutic resistance. Furthermore, its drastic difference in protein expression levels between normal and tumor tissues suggests that targeting B7-H3 with drugs would lead to cancer-specific toxicity, minimizing harm to healthy cells. These properties make B7-H3 a promising target for cancer therapy.Recently, important advances in B7-H3 research and drug development have been reported, and these new findings, including its involvement in cellular metabolic reprograming, cancer stem cell enrichment, senescence and obesity, have expanded our knowledge and understanding of this molecule, which is important in guiding future strategies for targeting B7-H3. In this review, we briefly discuss the biology and function of B7-H3 in cancer development. We emphasize more on the latest findings and their underlying mechanisms to reflect the new advances in B7-H3 research. In addition, we discuss the new improvements of B-H3 inhibitors in cancer drug development.

Heterogeneous Expression and Subcellular Localization of Pyruvate Dehydrogenase Complex in Prostate Cancer

Background

Pyruvate dehydrogenase (PDH) complex converts pyruvate into acetyl-CoA by pyruvate decarboxylation, which drives energy metabolism during cell growth, including prostate cancer (PCa) cell growth. The major catalytic subunit of PDH, PDHA1, is regulated by phosphorylation/dephosphorylation by pyruvate dehydrogenase kinases (PDKs) and pyruvate dehydrogenase phosphatases (PDPs). There are four kinases, PDK1, PDK2, PDK3 and PDK4, which can phosphorylate and inactivate PDH; and two phosphatases, PDP1 and PDP2, that dephosphorylate and activate PDH.

Methods

We have analyzed by immunohistochemistry the expression and clinicopathological correlations of PDHA1, PDP1, PDP2, PDK1, PDK2, PDK3, and PDK4, as well as of androgen receptor (AR), in a retrospective PCa cohort of patients. A total of 120 PCa samples of representative tumor areas from all patients were included in tissue microarray (TMA) blocks for analysis. In addition, we studied the subcellular localization of PDK2 and PDK3, and the effects of the PDK inhibitor dichloroacetate (DCA) in the growth, proliferation, and mitochondrial respiration of PCa cells.

Results

We found heterogeneous expression of the PDH complex components in PCa tumors. PDHA1, PDP1, PDK1, PDK2, and PDK4 expression correlated positively with AR expression. A significant correlation of PDK2 immunostaining with biochemical recurrence and disease-free survival was revealed. In PCa tissue specimens, PDK2 displayed cytoplasmic and nuclear immunostaining, whereas PDK1, PDK3 and PDK4 showed mostly cytoplasmic staining. In cells, ectopically expressed PDK2 and PDK3 were mainly localized in mitochondria compartments. An increase in maximal mitochondrial respiration was observed in PCa cells upon PDK inhibition by DCA, in parallel with less proliferative capacity.

Conclusion

Our findings support the notion that expression of specific PDH complex components is related with AR signaling in PCa tumors. Furthermore, PDK2 expression associated with poor PCa prognosis. This highlights a potential for PDH complex components as targets for intervention in PCa.

Novel human melanoma brain metastasis models in athymic nude fox1nu mice: Site-specific metastasis patterns reflecting their clinical origin

BACKGROUND

Malignant melanomas frequently metastasize to the brain, but metastases in the cerebellum are underrepresented compared with metastases in the cerebrum.

METHODS

We established animal models by injecting intracardially in athymic nude fox1nu mice two human melanoma cell lines, originating from a cerebral metastasis (HM19) and a cerebellar metastasis (HM86).

RESULTS

Using magnetic resonance imaging (MRI), metastases were first detected after a mean of 34.5 days. Mean survival time was 59.6 days for the mice in the HM86 group and significantly shorter (43.7 days) for HM19-injected animals (p < 0.001). In the HM86 group, the first detectable metastasis was located in the cerebellum in 15/55 (29%) mice compared with none in the HM19 group (p < 0.001). At sacrifice, cerebellar metastases were found in 34/55 (63%) HM86-injected mice compared with 1/53 (2%) in the HM19-injected (p < 0.001) mice. At that time, all mice in both groups had detectable metastases in the cerebrum. Comparing macroscopic and histologic appearances of the brain metastases with their clinical counterparts, the cell line-based tumors had kept their original morphologic characteristics.

CONCLUSIONS

The present work demonstrates that human brain-metastatic melanoma cells injected intracardially in mice had retained inherent characteristics also in reproducing interaction with subtle microenvironmental brain tissue compartment-specific features. The models offer new possibilities for investigating tumor- and host-associated factors involved in determining tissue specificity of brain metastasis.

Immune checkpoint B7-H3 protein expression is associated with poor outcome and androgen receptor status in prostate cancer

BACKGROUND

Novel immune checkpoint-based immunotherapies may benefit specific groups of prostate cancer patients who are resistant to other treatments.

METHODS

We analyzed by immunohistochemistry the expression of B7-H3, PD-L1/B7-H1, and androgen receptor (AR) in tissue samples from 120 prostate adenocarcinoma patients treated with radical prostatectomy in Spain, and from 206 prostate adenocarcinoma patients treated with radical prostatectomy in Norway.

RESULTS

B7-H3 expression correlated positively with AR expression and was associated with biochemical recurrence in the Spanish cohort, but PD-L1 expression correlated with neither of them. Findings for B7-H3 were validated in the Norwegian cohort, where B7-H3 expression correlated positively with Gleason grade, surgical margins, seminal vesicle invasion, and CAPRA-S risk group, and was associated with clinical recurrence. High B7-H3 expression in the Norwegian cohort was also consistent with positive AR expression.

CONCLUSION

These results suggest distinct clinical relevance of the two immune checkpoint proteins PD-L1 and B7-H3 in prostate cancer. Our findings highlight B7-H3 as an actionable novel immune checkpoint protein in prostate cancer.

Increased Local Inflammatory Response to MOC31PE Immunotoxin After Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy

Background

Despite extensive cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS-HIPEC), most patients with resectable peritoneal metastases from colorectal cancer experience disease relapse. MOC31PE immunotoxin is being explored as a novel treatment option for these patients. MOC31PE targets the cancer-associated epithelial cell adhesion molecule, and kills cancer cells by distinct mechanisms, simultaneously causing immune activation by induction of immunogenic cell death (ICD).

Methods

Systemic and local cytokine responses were analyzed in serum and intraperitoneal fluid samples collected the first three postoperative days from clinically comparable patients undergoing CRS-HIPEC with (n = 12) or without (n = 26) intraperitoneal instillation of MOC31PE. A broad panel of 27 pro- and antiinflammatory interleukins, chemokines, interferons, and growth factors was analyzed using multiplex technology.

Results

The time course and magnitude of the systemic and local postoperative cytokine response after CRS-HIPEC were highly compartmentalized, with modest systemic responses contrasting substantial intraperitoneal responses. Administration of MOC31PE resulted in changes that were broader and of higher magnitude compared with CRS-HIPEC alone. Significantly increased levels of innate proinflammatory cytokines, such as interleukin (IL)-6, IL-1β, and tumor necrosis factor (TNF) as well as an interesting time response curve for the strong T-cell stimulator interferon (IFN)-γ and its associated chemokine interferon gamma-induced protein/chemokine (C-X-C motif) ligand 10 (IP-10) were detected, all associated with ICD.

Conclusions

Our study revealed a predominately local rather than systemic inflammatory response to CRS-HIPEC, which was strongly enhanced by MOC31PE treatment. The MOC31PE-induced intraperitoneal inflammatory reaction could contribute to improve remnant cancer cell killing, but the mechanisms remain to be elucidated in future studies.

Supplementary Information

The online version contains supplementary material available at 10.1245/s10434-021-10022-0.

B7-H3 Immune Checkpoint Protein in Human Cancer

B7-H3 belongs to the B7 family of immune checkpoint proteins, which are important regulators of the adaptive immune response and emerging key players in human cancer. B7-H3 is a transmembrane protein expressed on the surface of tumor cells, antigen presenting cells, natural killer cells, tumor endothelial cells, but can also be present in intra- and extracellular vesicles. Additionally, B7-H3 may be present as a circulating soluble isoform in serum and other body fluids. B7-H3 is overexpressed in a variety of tumor types, in correlation with poor prognosis. B7-H3 is a promising new immunotherapy target for anti-cancer immune response, as well as a potential biomarker. Besides its immunoregulatory role, B7-H3 has intrinsic pro-tumorigenic activities related to enhanced cell proliferation, migration, invasion, angiogenesis, metastatic capacity and anti-cancer drug resistance. B7-H3 has also been found to regulate key metabolic enzymes, promoting the high glycolytic capacity of cancer cells. B7-H3 receptors are still not identified, and little is known about the molecular mechanisms underlying B7-H3 functions. Here, we review the current knowledge on the involvement of B7-H3 in human cancer.

Immune stimulatory effect of anti-EpCAM immunotoxin - improved overall survival of metastatic colorectal cancer patients

Introduction: In a recent phase I trial in a heterogeneous group of carcinoma patients with advanced disease, we did not observe objective responses by CT at 8 weeks in patients treated with either the anti-EpCAM immunotoxin MOC31PE alone or administered in combination with the immunosuppressor cyclosporin (CsA). We have now assessed overall survival (OS) data for the two groups to reveal potential differences, and to elucidate putative underlying mechanisms.Material and methods: The OS time of MOC31PE monotherapy (34 patients) and MOC31PE in combination with CsA (23 patients), was assessed. Pre- and post-treatment patient sera were analyzed in a multiplex immunoassay, and the immunogenic effects of MOC31PE were studied in vitro and in a dendritic cell maturation assay.Results: When the data were analyzed for all treated patients regardless of cancer type, the MOC31PE alone group had a median OS of 12.7 months (95% CI = 5.6-19.8 months) compared to 6.2 months (95% CI = 5.6-6.8 months) (p=.066) for the patients treated with MOC31PE + CsA group. For the subgroup of patients with colorectal cancer, the median OS survival was 16.3 months (95% CI = 5.6-27.0) for the MOC31PE only cohort (n = 15), compared to 6.0 months (CI = 5.8-6.2) (p < .001) for the combination group. The cytokine profile in patient sera and the in vitro immunological studies indicate that MOC31PE induced an immunogenic response leading to T-cell activation; a response that was suppressed in patients treated with MOC31PE + CsA.Conclusions: The results reveal a promising clinical benefit of anti-EpCAM immunotoxin treatment in patients with advanced disease, an effect apparently explained by a previously unknown immunogenic effect of MOC31PE.

Cytoplasmic expression of B7-H3 and membranous EpCAM expression are associated with higher grade and survival outcomes in patients with clear cell renal cell carcinoma

B7-H3 and EpCAM are overexpressed in cancer and play a role in tumorigenesis and metastasis. In this study, the membranous, cytoplasmic and nuclear expression levels of B7-H3 and EpCAM biomarkers were mapped in three major subtypes of renal cell carcinoma (RCC). Expression of B7-H3 and EpCAM were evaluated using immunohistochemistry in RCC samples on tissue microarrays (TMAs), including clear cell RCCs (ccRCCs), type I and II papillary RCCs (pRCCs), and chromophobe RCCs (chRCCs). The association between B7-H3 and EpCAM expression and clinicopathological features as well as survival outcomes was determined. There was a statistically significant difference between B7-H3 and EpCAM expression among the different RCC subtypes. In ccRCC, higher cytoplasmic expression of B7-H3 was significantly associated with increase in nucleolar grade, lymph node invasion (LNI), invasion of the Gerota's fascia, and tumor necrosis, while no association was found with the membranous and nuclear expression. Moreover tumors with cytoplasmic expression of B7-H3 tended to have a worse prognosis for disease-specific survival (DSS) than those with membranous expression. In case of EpCAM, increased membranous expression of EpCAM was associated with nucleolar grade and tumor necrosis in ccRCC. Additionally, membranous EpCAM expression added prognostic value in patients with ccRCC who had high nucleolar grade versus low nucleolar grade. Moreover, membranous EpCAM expression was found to be an independent favorable prognostic marker for progression-free survival (PFS) in ccRCC. Our results demonstrated that higher cytoplasmic B7-H3 and membranous EpCAM expression are clinically significant in ccRCC and are associated with more aggressiveness tumor behavior.

Spheroid-Derived Cells From Renal Adenocarcinoma Have Low Telomerase Activity and High Stem-Like and Invasive Characteristics

Cancer stem cells (CSCs) are a theorized small subpopulation of cells within tumors thought to be responsible for metastasis, tumor development, disease progression, treatment-resistance, and recurrence. The identification, isolation, and biological characterization of CSCs may therefore facilitate the development of efficient therapeutic strategies targeting CSCs. This study aims to compare the biology and telomerase activity of CSCs to parental cells (PCs) in renal cancer. Renal CSCs were enriched from the ACHN cell line using a sphere culture system. Spheroid-derived cells (SDCs) and their adherent counterparts were compared with respect to their colony and sphere formation, expression of putative CSC markers, tumorigenicity in non-obese diabetic/severe combined immunodeficiency (NOD/SCID) mice, and invasiveness. The expression of genes associated with CSCs, stemness, EMT, apoptosis, and ABC transporters was also compared between the two populations using quantitative real-time PCR (qRT-PCR). Finally, telomerase activity, hTERT expression, and sensitivity to MST-312, a telomerase inhibitor, was investigated between the two populations. We demonstrated that a subpopulation of ACHN cells was capable of growing as spheroids with many properties similar to CSCs, including higher clonogenicity, superior colony- and sphere-forming ability, and stronger tumorigenicity and invasiveness. In addition, SDCs demonstrated a higher expression of markers for CSCs, stemness, EMT, apoptosis, and ABC transporter genes compared to PCs. The expression of hTERT and telomerase activity in SDCs was significantly lower than PCs; however, the SDC population was more sensitive to MST-312 compared to PCs. These findings indicate that the SDC population exhibits stem-like potential and invasive characteristics. Moreover, the reduced expression of hTERT and telomerase activity in SDCs demonstrated that the expressions of hTERT and telomerase activity are not always higher in CSCs. Our results also showed that MST-312 treatment inhibited SDCs more strongly than PCs and may therefore be useful as a complementary targeted therapy against renal CSCs in the future.

ImmunoPeCa trial: Long-term outcome following intraperitoneal MOC31PE immunotoxin treatment in colorectal peritoneal metastasis

BACKGROUND

The ImmunoPeCa trial investigated the use of intraperitoneal MOC31PE immunotoxin as a novel therapeutic principle for the treatment of peritoneal metastasis from colorectal cancer (PM-CRC). We here report long-term outcome from the trial.

METHODS

This was a dose-finding trial aiming to evaluate safety and toxicity (primary endpoint) upon a single dose of intraperitoneal MOC31PE in patients with PM-CRC undergoing CRS-HIPEC with mitomycin C. Overall survival (OS) and disease-free survival (DFS) were secondary endpoints. Twenty-one patients received the study drug at four dose levels on the first postoperative day, including six patients constituting an expansion cohort.

RESULTS

With a 34-month follow-up, the median OS was not reached and the estimated 3-year OS was 78%. Median DFS for all patients was 21 months and the 3-year DFS was 33%, with a median follow-up of 31 months. When excluding patients with potential favorable characteristics from the analysis (n = 4), the median DFS was 13 months and the 3-year OS 72%.

CONCLUSIONS

The promising long-term outcome combined with low systemic absorbance, high drug concentration and cytotoxic activity in peritoneal fluid support further investigations of clinical efficacy.

p38 MAPK activation through B7-H3-mediated DUSP10 repression promotes chemoresistance

Immunoregulatory protein B7-H3 is involved in the oncogenic and metastatic potential of cancer cells, as well as in drug resistance. Resistance to conventional chemotherapy is an important aspect of melanoma treatment, and a better understanding of how B7-H3 enhances drug resistance may lead to the development of more effective therapies. We investigated the in vitro and in vivo sensitivity of chemotherapeutic agents dacarbazine (DTIC) and cisplatin in sensitive and drug resistant melanoma cells with knockdown expression of B7-H3. We found that knockdown of B7-H3 increased in vitro and in vivo sensitivity of melanoma cells to the chemotherapeutic agents dacarbazine (DTIC) and cisplatin, in parallel with a decrease in p38 MAPK phosphorylation. Importantly, in B7-H3 knockdown cells we observed an increase in the expression of dual-specific MAP kinase phosphatase (MKP) DUSP10, a MKP known to dephosphorylate and inactivate p38 MAPK. DUSP10 knockdown by siRNA resulted in a reversion of the increased DTIC-sensitivity seen in B7-H3 knockdown cells. Our findings highlight the potential therapeutic benefit of combining chemotherapy with B7-H3 inhibition, and indicate that B7-H3 mediated chemoresistance in melanoma cells is driven through a mechanism involving DUSP10-mediated inactivation of p38 MAPK.

Human telomerase reverse transcriptase protein expression predicts tumour aggressiveness and survival in patients with clear cell renal cell carcinoma

Human telomerase reverse transcriptase (hTERT) is an active component of telomerase and responsible for its catalytic activity, associated with cell proliferation and differentiation. For the first time, the present study was conducted to evaluate the expression and prognostic significance of hTERT in different histological subtypes of renal cell carcinoma (RCC). Expression of hTERT was examined in 176 well-defined renal tumour samples including clear cell RCCs (ccRCCs), papillary and chromophobe RCCs using immunohistochemistry on tissue microarrays. The association between hTERT expression and clinicopathological parameters as well as survival outcomes were then analysed. There was a statistically significant difference in terms of hTERT expression among various RCC subtypes. In ccRCC, increased expression of hTERT was significantly associated with advanced stage, higher grade, presence of microvascular invasion, lymph node invasion, and metastasis. Moreover, in the multivariate analysis, tumour stage and tumour size were independent predictors of the disease-specific survival (DSS). Additionally, expression of hTERT was found to be a significant predictor of worse DSS (p = 0.012) in the univariate analysis. In papillary carcinoma samples (type I and II), significant association was detected between hTERT expression and the tumour stage (p = 0.010, p = 0.050), respectively. In chromophobe RCC, no significant association was detected between expression of hTERT and clinicopathological parameters and survival data. We showed that hTERT protein expression was associated with more aggressive tumour behaviour and more advanced disease in ccRCC patients. Also, hTERT may be a novel poor prognostic indicator of DSS, if the patients are followed for more prolonged time periods.

Abstract 2745: EpCAM targeted immunotoxin prolongs survival of metastatic colorectal cancer patients by a previously unknown immunostimulatory mechanism

A first-in-man study of the anti-EpCAM immunotoxin MOC31PE with and without parallel immunosuppression with Cyclosporin A (CsA) was performed in metastatic colorectal cancer (CRC) patients. The safety and maximum tolerable doses in patients with EpCAM-positive tumors were determined, and only mild and reversible dose-limiting liver toxicity was seen, with no subjective side effects to the patients. Although no complete or partial responses were observed on CT scans at eight weeks, upon evaluation of the overall survival (OS) of the patients we surprisingly found that CRC patients treated with immunotoxin alone (n=15) had a median OS of 16.3 months (95% CI=5.6-27.0) compared to 6.0 months (CI=5.8-6.2) (p&lt;0.001) for the combination group (n=18) (hazard ratio (HR): 0.248, 95% credible interval (CrI): 0.109-0.564). The 6.0 months OS for the patients treated with CsA in addition to the immunotoxin is comparable to OS of patients with progressive disease on last line of standard chemotherapy. The Th1 cytokine profile in sera from patients treated with MOC31PE alone indicated that the immuntoxin induces an immunogenic cell death resulting in T-cell activation, and that this effect disappeared in the patients who had received simultaneous treatment with CsA. Further, we demonstrate in in vitro experiments that the immunogenic cell death factors ATP and HMGB1 were secreted from CRC cell lines treated with MOC31PE alone. Finally, conditioned media from MOC31PE treated CRC cells induced maturation of dendritic cells and promoted activation of killer (CD8+) and helper (CD4+) T cells, showing that MOC31PE treatment induces release of immune stimulating factors. The present results demonstrate the novel and exciting finding that MOC31PE induces an immunogenic effect resulting in prolonged overall survival of patients with metastatic CRC, an effect obliterated by the parallel immunosuppression of CsA.

Citation Format: Øystein Fodstad, Svein Dueland, Kjersti Flatmark, Else Marit Inderberg, Gunnar Kvalheim, Yvonne Andersson. EpCAM targeted immunotoxin prolongs survival of metastatic colorectal cancer patients by a previously unknown immunostimulatory mechanism [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2745.

B7-H3 in Cancer - Beyond Immune Regulation

B7-H3, a member of the B7 family of immunoregulatory proteins, is overexpressed in cancer and promotes tumor growth, metastasis, and drug resistance. We discuss here the involvement of B7-H3 in cancer that goes beyond its immune regulatory function, and discuss the potential of B7-H3 as a biomarker and therapeutic target.

Immunoregulatory protein B7-H3 promotes growth and decreases sensitivity to therapy in metastatic melanoma cells

B7-H3 (CD276) belongs to the B7 family of immunoregulatory proteins and has been implicated in cancer progression and metastasis. In this study, we found that metastatic melanoma cells with knockdown expression of B7-H3 showed modest decrease in proliferation and glycolytic capacity and were more sensitive to dacarbazine (DTIC) chemotherapy and small-molecule inhibitors targeting MAP kinase (MAPK) and AKT/mTOR pathways: vemurafenib (PLX4032; BRAF inhibitor), binimetinib (MEK-162; MEK inhibitor), everolimus (RAD001; mTOR inhibitor), and triciribidine (API-2; AKT inhibitor). Similar effects were observed in melanoma cells in the presence of an inhibitory B7-H3 monoclonal antibody, while the opposite was seen in B7-H3-overexpressing cells. Further, combining B7-H3 inhibition with small-molecule inhibitors resulted in significantly increased antiproliferative effect in melanoma cells, as well as in BRAF^V600E mutated cell lines derived from patient biopsies. Our findings indicate that targeting B7-H3 may be a novel alternative to improve current therapy of metastatic melanoma.

Novel Treatment with Intraperitoneal MOC31PE Immunotoxin in Colorectal Peritoneal Metastasis: Results From the ImmunoPeCa Phase 1 Trial

BACKGROUND

MOC31PE immunotoxin was developed to rapidly kill cells expressing the tumor-associated epithelial cell adhesion molecule, which is highly expressed in colorectal cancer. Although cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) may offer long-term survival to patients with peritoneal metastasis from colorectal cancer (PM-CRC), most patients experience disease relapse and novel therapeutic options are needed. On this basis, MOC31PE is being developed as a novel therapeutic principle to target PM-CRC.

METHODS

This was a dose-escalating phase I trial to evaluate the safety and toxicity (primary endpoint), pharmacokinetic profile, and neutralizing antibody response (secondary endpoints) upon intraperitoneal administration of MOC31PE in patients with PM-CRC undergoing CRS-HIPEC with Mitomycin C. Fifteen patients received the study drug at four dose levels (3+3+3+6), administered intraperitoneally as a single dose the day after CRS-HIPEC.

RESULTS

No dose-limiting toxicity was observed, and the maximum tolerated dose was not reached. There was negligible systemic absorption of the study drug. Drug concentrations in peritoneal fluid samples were in the cytotoxic range and increased in a dose-dependent manner. MOC31PE recovered from peritoneal cavity retained its cytotoxic activity in cell-based assays. All patients developed neutralizing antibodies.

CONCLUSIONS

Intraperitoneal administration of MOC31PE was safe and well tolerated, and combined with low systemic uptake, MOC31PE seems ideal for local intraperitoneal treatment. The drug will be further evaluated in an ongoing phase II expansion cohort.

Decreased expression of B7-H3 reduces the glycolytic capacity and sensitizes breast cancer cells to AKT/mTOR inhibitors

B7 family proteins are important immune response regulators, and can mediate oncogenic signaling and cancer development. We have used human triple-negative breast cancer cell lines with different expression levels of B7-H3 to evaluate its effects on the sensitivity to 22 different anticancer compounds in a drug screen. API-2 (triciribidine) and everolimus (RAD-001), two inhibitors that target the PI3K/AKT/mTOR pathway, showed enhanced inhibition of cell viability and proliferation in B7-H3 knockdown tumor cells compared to their B7-H3 expressing counterparts. Similar inhibition was seen in control cells treated with an anti-B7-H3 monoclonal antibody. In B7-H3 overexpressing cells, the effects of the two drugs were reduced, supported also by in vivo experiments in which B7-H3 overexpressing xenografts were less sensitive to everolimus than control tumors. In API-2 and everolimus-treated B7-H3 overexpressing cells, phospho-mTOR levels were decreased. However, phosphorylation of p70S6K was differentially regulated in B7-H3 cells treated with API-2 or everolimus, suggesting a different B7-H3-mediated mechanism downstream of mTOR. Both API-2 and everolimus decreased the glycolysis of the cells, whereas knockdown of B7-H3 decreased and B7-H3 overexpression increased the glycolytic capacity. In conclusion, we have unveiled a previously unknown relationship between B7-H3 expression and glycolytic capacity in tumor cells, and found that B7-H3 confers resistance to API-2 and everolimus. The results provide novel insights into the function of B7-H3 in cancer, and suggest that targeting of B7-H3 may be a novel alternative to improve current anticancer therapies.

Abstract 4133: Suppressed B7-H3 expression reduces glycolytic capacity and sensitizes tumor cells to anti-cancer agents

B7 family proteins are important immune response regulators, and can mediate oncogenicity-related signals and support cancer development. We have prevously shown that the B7-H3 protein promotes tumor cell invasion, proliferation and mestastasis, and increases resistance to chemotherapy. Now we have used human breast and melanoma cancer cell lines with different expression levels of B7-H3 to further evaluate the role of B7-H3 on the sensitivity to anticancer compounds. B7-H3 knockdown tumor cells showed enhanced chemosensitivity compared to their B7-H3 expressing counterparts, as well as increased inhibition to treatment with compounds that target proteins in the PI3K/AKT/mTOR- and MAPK-pathways (Nunes-Xavier et al. in revision). Treatment of control cells with an anti-B7-H3 monoclonal antibody resulted in similar sensitization, whereas B7-H3 overexpressing cells and xenografts were less sensitive. Of note, knockdown of B7-H3 decreased and B7-H3 overexpression increased the glycolytic capacity of the breast cancer and malignant melanoma cells. In conclusion, we have demonstrated a previously unknown relationship between B7-H3 expression and glycolysis in tumor cells, and found that B7-H3 confers resistance to also to pathway inhibiting agents. The results provide novel insights into the function of B7-H3 in cancer, and suggest that targeting of B7-H3 expression may be a promising alternative to improve current anticancer therapy.

Citation Format: Caroline E. Nunes-Xavier, Karine Flem Karlsen, Tove Øyjord, Ming Tan, Øystein Fodstad. Suppressed B7-H3 expression reduces glycolytic capacity and sensitizes tumor cells to anti-cancer agents. [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 4133.

Abstract CT055: Novel intraperitoneal treatment for peritoneal metastases: results from the Immunotoxin in Peritoneal Carcinomatosis (ImmunoPeCa) phase I clinical trial

Introduction: Peritoneal metastasis from colorectal cancer (PM-CRC) is a condition with poor prognosis, even in patients undergoing potentially curative treatment with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS-HIPEC). The ImmunoPeCa trial explores the tolerability of combining intraperitoneally administered MOC31PE immunotoxin with CRS-HIPEC. MOC31PE, consisting of the monoclonal antibody MOC31, which recognizes the tumor associated cell surface antigen EpCAM, and Pseudomonas exotoxin (PE), has shown excellent anti-cancer efficacy in preclinical studies. The immunotoxin was well tolerated upon intravenous administration in a previous clinical phase I trial, where the dose limiting toxicity (DLT) was reversible liver toxicity. In this trial, MOC31PE was administered intraperitoneally in humans for the first time, with the rationale that killing residual cancer cells in the peritoneal cavity after CRS-HIPEC will improve outcome.

Patients and methods: The ImmunoPeCa phase I/II clinical trial (NCT02219893) startet enrollment in 2014 and adult patients with EpCAM positive PM-CRC accepted for CRS-HIPEC were included. MOC31PE was administered on the first postoperative day through abdominal drainage catheters that were clamped for 6h before they were reopened to remove intraabdominal fluid. Standard dose escalation was applied, with four dose levels (2.5, 5.0, 7.5 and 10 μg/kg). Main endpoints were safety and toxicity (CTCAE version 4.0), and pharmacokinetic analyses of serum and peritoneal fluid were performed.

Results: Twelve patients have received MOC31PE without major toxicity, and a maximum tolerated dose was not reached. Interestingly, MOC31PE was not detected in patient serum, suggesting that there was no systemic absorption of the drug. In peritoneal fluid samples at 6h and 24h MOC31PE was present in cytotoxic concentrations based on in vivo and in vitro studies, at least for the two highest dose levels, and the drug was impressively still fully active when analyzed in cell based assays.

Conclusions: No DLT was observed upon peritoneal administration of MOC31PE, which is consistent with no systemic absorption. Remarkably, MOC31PE was fully active in peritoneal fluid samples 24h after treatment, with the intraperitoneal drug concentration in the cytotoxic range based on in vitro and in vivo studies. Taken together, treatment with MOC31PE represents a unique possibility for intraperitoneal treatment intensification without systemic toxicity. The highest dose level (10 μg/kg) has been chosen for further testing in a planned phase II expansion of the trial.

Citation Format: Kjersti Flatmark, Yvonne Andersson, Ben Davidson, Svein Dueland, Øystein Fodstad, Ida S. Frøysnes, Karl Erik Giercksky, Lars Julsrud, Stein G. Larsen, Kari H. Olsen, Janne M T Øien. Novel intraperitoneal treatment for peritoneal metastases: results from the Immunotoxin in Peritoneal Carcinomatosis (ImmunoPeCa) phase I clinical trial. [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 CT055.

Detection of disseminated tumor cells in lymph nodes from patients with early stage non-small cell lung cancer

BACKGROUND

The regional lymph node involvement is a major prognostic factor in patients with non-small cell lung cancer (NSCLC) undergoing surgical resection. Disease relapse is common, suggesting that early disseminated disease is already present in the regional lymph nodes at the time of surgery, and that the current nodal staging classification might be suboptimal. Early detection of disseminated tumor cells (DTCs) in lymph nodes could potentially enable identification of subcategories of patients with high risk of disease relapse.

METHOD

Lymph node samples were collected from 128 NSCLC patients at the time of surgery and the presence of DTCs determined by immunomagnetic selection (IMS) using the MOC31 antibody recognizing EpCAM. Results obtained with IMS were compared to the pathological staging obtained by histopathology. Associations between the presence of DTCs and clinicopathological variables and patient outcome were investigated.

RESULTS

DTCs were detected in 40 % of the lymph node samples by IMS. Their presence was significantly associated with pN status as assessed by histopathology, and samples from 83 % of the patients with lymph node metastases (pN1-2) had detectable DTCs. In the group of patients who were negative for lymph node metastases by standard histopathology (pN0) DTCs were detected in 32 %. The presence of DTCs was not associated with any other clinicopathological variables. Patients with IMS-positive samples showed decreased relapse free survival compared to patients with IMS-negative samples, but the difference was not statistically significant. The pN status was significantly associated with both relapse free and overall survival, but the presence of DTCs had no prognostic impact in the subcategory of patients with pN0 status.

CONCLUSION

Our findings do not support further development of lymph node DTC detection for clinical use in early stage NSCLC.

Bilateral uveal melanomas with different gene expression detected with 7 years interval

PURPOSE

To report a bilateral uveal melanoma detected in a micrometastasis study.

METHOD

Case report.

RESULTS

At enucleation of a circumpapillary amelanotic mixed melanoma in a patient with ocular melanocytosis, a pigmented lesion in the other eye was detected, thought to be a naevus. BAP1 was positive showing nuclear staining of the tumour cells. Seven years later the naevus showed growth and development of a retinal detachment. FNAB disclosed monosomy 3 in the spindle tumour cells.

CONCLUSION

A case of bilateral melanoma with long-term survival without metastatic diseases is reported. Different gene expressions in the two eyes were revealed. The case is a reminder that follow-up over years is essential in patients with a uveal melanoma, especially with ocular melanocytosis.

Immunomagnetic detection of micrometastatic cells in bone marrow of uveal melanoma patients: a paradox

PURPOSE

Our objective was to study survival rates with the bone marrow (BM) results in a cohort of uveal melanoma patients with long follow-up.

METHODS

Mononuclear cell fractions isolated from BM were examined for tumour cells using our immunomagnetic separation (IMS) method. The patients were classified as BM positive or BM negative. Clinical follow-up, histopathological findings, vital status and cause of death were registered.

RESULTS

The study included 328 consecutive patients with uveal melanoma from 1997 to 2006. Tumour cells were found in BM samples in 29% (95% CI, 25-34) at enrolment (96 cases). After a minimum follow-up time of 6 years, 156 (48%) (95% CI, 42-53) melanoma patients had died. The causes were as follows: melanoma metastases 92 (59%), another cancer 20 (13%) and non-cancer 44 (28%). Nine patients were still living with melanoma metastases. Until the latest work-up, 101(31%) (95% CI, 26-36) patients had developed melanoma metastases. Cyto- or histopathological verification of the metastatic lesions was obtained in 85 cases (84%). In the group with melanoma metastases, 28 tested BM positive at study entry (28%) (95% CI, 19-38). In total, 39 of 101 with metastases tested positive at least once after a maximum of three tests (39%) (95% CI, 29-49). The overall median survival from the first BM test was shorter for the BM negative patients (9.5 years) compared with the BM positive (14.4 years), p = 0.02, log rank test.

CONCLUSION

Ocular melanoma cells detected in BM seem to have a positive prognostic impact on survival in contrast to our original hypothesis.

B7-H3 expression in colorectal cancer: associations with clinicopathological parameters and patient outcome

Background

We have previously reported overexpression of the immunoregulatory protein B7-H3 in colorectal cancer and that nuclear expression predicted poor outcome in colon cancer patients. The present study was performed to examine the prognostic role of B7-H3 in an independent colorectal cancer cohort.

Methods

Using tissue microarrays from 731 colorectal cancer patients, tumour B7-H3 expression was assessed by immunohistochemistry. Associations with clinicopathological parameters and patient outcome were investigated.

Results

Nuclear expression of B7-H3 in cancer cells was present in 27% of the samples in the total study cohort, while cytoplasmic/membrane and stromal expression was seen in 86% and 77% of the samples, respectively. Nuclear B7-H3 had no prognostic relevance in the complete outcome cohort, neither in colon cancer patients. However, nuclear B7-H3 was significantly associated with reduced recurrence-free survival in TNM stage I colorectal cancer patients.

Conclusions

Overexpression of B7-H3 in colorectal cancer was confirmed, but in contrast to previous results, nuclear B7-H3 was not a strong prognostic biomarker in this cohort. The discrepancy might be related to the use of single-core tissue microarrays for detection of the heterogeneously expressed B7-H3, and the role of B7-H3 in colorectal cancer still needs further examination.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2407-14-602) contains supplementary material, which is available to authorized users.

Immunotoxin targeting EpCAM effectively inhibits peritoneal tumor growth in experimental models of mucinous peritoneal surface malignancies

Cytoreductive surgery and intraperitoneal (i.p.) chemotherapy constitute a curative treatment option in mucinous peritoneal surface malignancies of intestinal origin, but treatment outcome is highly variable and the search for novel therapies is warranted. Immunotoxins are attractive candidates for targeted therapy in the peritoneal cavity because of direct cytotoxicity, distinct mechanisms of action and tumor cell selectivity. The MOC31PE immunotoxin targets the tumor-associated adhesion protein EpCAM (Epithelial Cell Adhesion Molecule), and has been administered safely in early clinical trials. In our work, the efficacy of i.p. administration of MOC31PE alone and together with mitomycin C (MMC) was investigated in unique animal models of human mucinous peritoneal surface malignancies. In initial model validation experiments, clear differences in efficacy were demonstrated between MMC and oxaliplatin, favoring MMC in five investigated tumor models. Subsequently, MOC31PE and MMC were given as single i.p. injections alone and in combination. In the PMCA-2 model, moderate growth inhibition was obtained with both drugs, while the combination resulted in at least additive effects; whereas the PMP-2 model was highly sensitive to both drugs separately and in combination and intermediate sensitivity was found for the PMCA-3 model. Furthermore, results from ex vivo experiments on freshly obtained mucinous tumor tissue from animals and patients suggested that classic mechanisms of immunotoxin activity were involved, i.e., inhibition of protein synthesis and induction of apoptosis. The present results suggest that adding MOC31PE to MMC-based i.p. chemotherapy should be further explored for EpCAM-expressing peritoneal surface malignancies, and a phase I trial is in preparation.

Clinical significance of disseminated tumour cells in non-small cell lung cancer

Background:

Early-stage non-small cell lung cancer (NSCLC) patients have a high risk of disease relapse despite curatively intended surgical resection, and the detection of tumour cells in the bone marrow could be one method of determining the presence of the disseminated disease in its early stages.

Methods:

Bone marrow aspirates were collected from 296 patients at the time of surgery, and the presence of disseminated tumour cells was determined with the help of immunomagnetic selection (IMS) using the MOC31-antibody recognising EpCAM and with the help of standard immunocytochemistry (ICC) using the anti-cytokeratin (CK) antibodies AE1/AE3.

Results:

Disseminated tumour cells were found in 152 of 252 (59%) bone marrow samples using IMS and in 25 of 234 (11%) samples using ICC. No association between the two detection methods was observed. The presence of EpCAM⁺ cells was not associated with any clinicopathological parameters, whereas a higher frequency of CK⁺ cells was found in patients with an advanced pT status. Disseminated tumour cells, as detected using IMS, had no prognostic impact. Patients with CK⁺ cells in the bone marrow had a reduced relapse-free survival, but the difference was not statistically significant.

Conclusion:

Our findings do not support the further development of DTC detection for clinical use in early-stage NSCLC. Future studies should include the molecular characterisation of DTCs, along with an attempt to identify subpopulations of cells with biological and clinical significance.

Disseminated tumour cells in bone marrow of patients with uveal melanoma

PURPOSE

Approximately 50% of patients with uveal melanomas develop metastases. Thus, it is important to improve our understanding of how melanoma metastases develop.

METHODS

As part of a uveal melanoma micrometastasis study, we compared the detection rates of immunomagnetically selected (IMS) tumour cells in bone marrow (BM) with positively stained tumour cells using immunocytochemistry (ICC). Bone marrow mononuclear cells were isolated. Immunocytochemistry cytospin preparations were immunocytochemically stained in parallel with two different melanoma antibodies, 9.2.27 and HMB45. Using IMS, melanoma cells were selected from BM mononuclear cell fractions using immunomagnetic beads coated with the 9.2.27 antibody and identified by light microscopy.

RESULTS

In cytospin preparations from 226 patients, melanoma cells were detected in 24 (10.6%), 10 with 9.2.27 and 17 with the HMB45 antibody. In three cases, we found positive cells with both antibodies. Six of the 226 (2.6%) patients that stained positively with ICC died with metastatic disease, all also positive with IMS. Sixty-six (29.2%) patients had positive BM samples with IMS at the first examination. Immunomagnetic selection (IMS) was positive in 36.8% of the 57 patients who later developed clinical metastases. Twenty-one IMS-positive patients and 31 IMS-negative patients died of metastases, in total 52 of 226 patients (23.0%). The mortality rate of melanoma metastasis was 24% (6/24) after at least 4 ½ years in ICC-positive patients compared to 38.5% (20/52) in IMS-positive patients.

CONCLUSION

The presence of melanoma cells in BM of patients with uveal melanoma is documented in our study with IMS and ICC. Immunomagnetically selected is more sensitive than ICC in detecting tumour cells in BM. However, statistically, we did not find any prognostic impact of the presence of melanoma cells in BM.

Abstract 1840: Clinical significance of lincRNA-p21 in colorectal cancer

Large Intergenic Noncoding RNAs (LincRNAs) have been recently shown to be novel regulators for both transcription and posttranscriptional/translation. One of them, lincRNA-p21, was regulated by p53 and contributed to apoptosis in mouse embryonic fibroblasts. However, the impact of such regulation on colorectal cancer (CRC) is remained to be determined. In this study, we discovered that the expression level of lincRNA-p21 was increased by elevated wild type p53 induced by Nutlin in HCT116 colon cancer cells. The clinical significance of lincRNA-p21 was further investigated in 2 CRC patient cohorts. The expression of lincRNA-p21 was quantified by the real time qRT-PCR analysis using total RNAs extracted from snap fresh frozen CRC samples. Our results reveal that the expression level of lincRNA-p21 is significantly (P = 0.0208) lower in CRC tumor tissue when compared to the paired normal tissue from the same patient. There is no significant correlation of lincRNA-p21 with p53 status (wild type vs. mutant). Tumors in rectum show higher level of lincRNA-p21 than the ones in colon (P = 0.00005). In addition, lincRNA-p21 in stage III patients was significantly higher than stage I patients (P = 0.007). Elevated level of lincRNA-p21 was significantly associated with higher pT (P = 0.037 between pT 2 and 3), and vascular invasion (P = 0.017). LincRNA-p21 was not significantly associated with patient's overall survival. These results indicate that lincRNA-p21 may contribute to CRC disease progression.

Citation Format: Haiyan Zhai, Andrew Fesler, Kristina Schee, Øystein Fodstad, Kjersti Flatmark, Jingfang Ju. Clinical significance of lincRNA-p21 in colorectal cancer. [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 1840. doi:10.1158/1538-7445.AM2013-1840

Clinical relevance of microRNA miR-21, miR-31, miR-92a, miR-101, miR-106a and miR-145 in colorectal cancer

Background

MicroRNAs (miRNAs) regulate gene expression by binding to mRNA, and can function as oncogenes or tumor suppressors depending on the target. In this study, using qRT-PCR, we examined the expression of six miRNAs (miR-21, miR-31, miR-92a, miR-101, miR-106a and miR-145) in tumors from 193 prospectively recruited patients with colorectal cancer, and associations with clinicopathological parameters and patient outcome were analyzed. The miRNAs were chosen based on previous studies for their biomarker potential and suggested biological relevance in colorectal cancer.

Methods

The miRNA expression was examined by qRT-PCR. Associations between miRNA expression and clinicopathological variables were explored using Mann–Whitney U and Kruskal-Wallis test while survival was estimated using the Kaplan-Meier method and compared using the log-rank test.

Results

MiR-101 was hardly expressed in the tumor samples, while for the other miRNAs, variable expression levels and expression ranges were observed, with miR-21 being most abundantly expressed relative to the reference (RNU44). In our study cohort, major clinical significance was demonstrated only for miR-31, as high expression was associated with advanced tumor stage and poor differentiation. No significant associations were found between expression of the investigated miRNAs and metastasis-free or overall survival.

Conclusions

Investigating the expression of six miRNAs previously identified as candidate biomarkers in colorectal cancer, few clinically relevant associations were detected in our patient cohort. Our results emphasize the importance of validating potential tumor markers in independent patient cohorts, and indicate that the role of miRNAs as colorectal cancer biomarkers is still undetermined.

Abstract LB-79: Synergistic anticancer effects of the 9.2.27PE immunotoxin and ABT-737 in melanoma involves silencing of the anti-apoptotic protein Mcl-1

In cancer, combinations of drugs targeting different cellular functions is well accepted to improve tumor control. We studied the effects of a Pseudomonas exotoxin A (PE)-based immunotoxin, the 9.2.27PE, and the Bcl-2 family inhibitor ABT-737 in a panel of melanoma cell lines. ABT-737 inhibits the Bcl-2, Bcl-xl and the Bcl-w, but not Mcl-1 and A1 of the Bcl-2 family. The 9.2.27PE + ABT-737 drug combination resulted in synergistic cytotoxicity in the melanoma cells independent of BRAF mutation status. The cell death observed was associated with apoptosis, as activation of caspase-3, inactivation of Poly (ADP-ribose) polymerase (PARP) and increased DNA fragmentation could be prevented by pre-treatment with caspase and cathepsin inhibitors. In addition, ABT-737 caused endoplasmic reticulum (ER) stress with increased GRP78, phosphorylated eIF2α protein levels and increased intracellular calcium levels. The increased intracellular calcium levels were enhanced by silencing of Mcl-1 by short hairpin RNA or by treatment with the 9.2.27PE immunotoxin. These results suggests that Mcl-1 has an inhibitory effect on calcium release from the ER, and that strongly decreased Mcl-1 protein levels after treatment with 9.2.27PE or shRNA may be responsible for the increased intracellular calcium levels in ABT-737 treated melanoma cells. Calcium release has been shown to take place through the inositol 1,4,5-triphosphate receptor in the ER membrane, and the Bcl-2 family proteins Bcl-2, Bcl-xl and Mcl-1 have been shown to interact with the inositol 1,4,5-triphosphate receptor, supporting our results.1 Notably, the combination of 9.2.27PE and ABT-737 caused growth delay in a human melanoma xenograft mice model. 1. Eckenrode EF et. Al., J Biol Chem. 2010 Apr 30;285(18):13678-84

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 LB-79. doi:1538-7445.AM2012-LB-79

Synergistic anticancer effects of the 9.2.27PE immunotoxin and ABT-737 in melanoma

In cancer, combinations of drugs targeting different cellular functions is well accepted to improve tumor control. We studied the effects of a Pseudomonas exotoxin A (PE)-based immunotoxin, the 9.2.27PE, and the BH-3 mimetic compound ABT-737 in a panel of melanoma cell lines. The drug combination resulted in synergistic cytotoxicity, and the cell death observed was associated with apoptosis, as activation of caspase-3, inactivation of Poly (ADP-ribose) polymerase (PARP) and increased DNA fragmentation could be prevented by pre-treatment with caspase and cathepsin inhibitors. We further show that ABT-737 caused endoplasmic reticulum (ER) stress with increased GRP78 and phosphorylated eIF2α protein levels. Moreover, treatment with ABT-737 increased the intracellular calcium levels, an effect which was enhanced by 9.2.27PE, which as a single entity drug had minimal effect on calcium release from the ER. In addition, silencing of Mcl-1 by short hairpin RNA (shRNA) enhanced the intracellular calcium levels and cytotoxicity caused by ABT-737. Notably, the combination of 9.2.27PE and ABT-737 caused growth delay in a human melanoma xenograft mice model, supporting further investigations of this particular drug combination.

Tumor kinase activity in locally advanced rectal cancer: angiogenic signaling and early systemic dissemination

Tumor hypoxia is a common determinant of resistance to cytotoxic therapies and metastatic behavior. In rectal cancer patients receiving preoperative chemoradiotherapy, tyrosine kinase activities in tumors with poor and good treatment responses were found to differ. Given that tyrosine kinase signaling mediates hypoxic tissue adaptation, the present study examined whether tumor kinase activity might also correlate with systemic dissemination of rectal cancer. Immunomagnetic selection of disseminated tumor cells (DTC) from bone marrow aspirates was undertaken in 55 patients with locally advanced rectal cancer. Using peptide arrays with 144 tyrosine kinase substrates, phosphopeptide signatures were generated from patients' baseline tumor biopsies, to study association between DTC and tumor tyrosine kinase activity regulated ex vivo by sunitinib. Disseminated tumor cells were detected in 60% of cases, and these patients had significantly poorer metastasis-free survival than patients without DTC. Phosphorylation of 31 array tyrosine kinase substrates by tumor samples was significantly more strongly inhibited by sunitinib in the DTC-negative patients, with a number of phosphosubstrates representing angiogenic factors. In this cohort of rectal cancer patients, tumor phenotypes defined by a subset of tyrosine kinase activities correlating with weak ex vivo inhibition by sunitinib, was associated with early systemic dissemination.

Analysis of EpCAM positive cells isolated from sentinel lymph nodes of breast cancer patients identifies subpopulations of cells with distinct transcription profiles

Introduction

The presence of tumor cells in the axillary lymph nodes is the most important prognostic factor in early stage breast cancer. However, the optimal method for sentinel lymph node (SLN) examination is still sought and currently many different protocols are employed. To examine two approaches for tumor cell detection we performed, in sequence, immunomagnetic enrichment and RT-PCR analysis on SLN samples from early stage breast cancer patients. This allowed us to compare findings based on the expression of cell surface proteins with those based on detection of intracellular transcripts.

Methods

Enrichment of EpCAM and Mucin 1 expressing cells from fresh SLN samples was achieved using magnetic beads coated with the appropriate antibodies. All resulting cell fractions were analyzed by RT-PCR using four chosen breast epithelial markers (hMAM, AGR2, SBEM, TFF1). Gene expression was further analyzed using RT-PCR arrays and markers for epithelial to mesenchymal transition (EMT).

Results

Both EpCAM and Mucin 1 enriched for the epithelial-marker expressing cells. However, EpCAM-IMS identified epithelial cells in 71 SLNs, whereas only 35 samples were positive with RT-PCR targeting breast epithelial transcripts. Further analysis of EpCAM positive but RT-PCR negative cell fractions showed that they had increased expression of MMPs, repressors of E-cadherin, SPARC and vimentin, all transcripts associated with the process of epithelial to mesenchymal transition.

Conclusions

The EpCAM IMS-assay detected tumor cells with epithelial and mesenchymal-like characteristics, thus proving to be a more robust marker than pure epithelial derived biomarkers. This finding has clinical implications, as most methods for SLN analysis today rely on the detection of epithelial transcripts or proteins.

Abstract 5226: In vivo imaging and molecular characterization of site-specific growth of malignant melanoma: a study of melanoma metastasis in experimental animal models

Metastatic melanoma is a very aggressive and fatal disease in need of novel therapeutic targets. Melanomas are notorious for the ability to disseminate to almost any organ. The ability to develop metastases at distant sites is not only a function of intrinsic properties of the malignant cells themselves, but is also influenced by a wide range of factors in the host microenvironment. Understanding of the biological role of the microenvironment in the establishment of metastases and identifying implicated factors, might uncover novel potential targets for anti-metastatic therapy. The aim of our study was to reveal characteristics of metastatic growth of melanoma in different anatomical sites in animal models through in vivo imaging and molecular approaches.

We have developed experimental metastasis models in nude mice based on intracardial (left ventricle) injection of the melanoma cell lines Melmet 1 and Melmet 5, established from two metastatic melanoma patients with different clinical presentations. A follow-up of melanoma cell migration and micro/macrometastases formation assessed by molecular and functional imaging in vivo (IVIS and PET), indicated that Melmet 5 could establish metastases in multiple organs (including brain, lung, lymph nodes, kidney, bone), while Melmet 1 displayed a more consistent preference for the brain. Flow cytometric analysis of metastatic organs, specifically brain and lungs, revealed the recruitment of bone marrow derived cells, identified as CD11b+/Gr-1+ myeloid cells and CD11b+/F4/80+ macrophages. These cell subpopulations have been linked to the formation of a (pre)metastatic niche, and we are presently investigating their contribution to the metastatic growth of melanoma. Further, we performed a comparative microarray study to investigate differential gene expression with respect to organ-specific environments. Specifically, we identified a set of genes altered in immunoselected melanoma cells purified from brain tissue. Among these genes were receptors involved in glutamate signaling, indicating metabolic changes associated with metastatic colonization of the brain. Furthermore, after separation of tumor cells, the remaining host brain tissue was also analyzed by gene expression profiling in order to reveal molecular changes induced in the stroma compartment by metastases. Compared to non-diseased brain, we found altered expression of genes implicated in biological activities such as immune defense, evasion of apoptosis and cell adhesion and migration. Based on the results obtained, we are currently performing functional studies on candidate genes to elucidate their role in metastatic growth of melanoma. Targeting focal points of communication between metastatic tumor cells and the host in distinct microenvironments may represent an anti-metastatic therapeutic strategy.

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 5226. doi:10.1158/1538-7445.AM2011-5226

Abstract 2423: B7-H3 contributes to increased metastatic potential of melanoma cells by interfering with the expression of metastasis-related genes

Metastatic malignant melanoma is a disease with a long time survival rate of only 5%. Since there is no effective treatment for advanced melanoma, detection of molecular markers involved in tumor progression and drug resistance can hopefully provide new insight in therapeutically aspects of this disease. We have been studying B7-H3 – a glycosylated transmembrane protein which has been shown to play a role in cancer progression through its immunoregulatory properties.

B7-H3 is highly expressed in melanoma cell lines as well as in clinical melanoma specimens, and we have previously demonstrated a role of the protein in chemoresistance. Thus, in this study, we wanted to investigate the possible function of B7-H3 in melanoma metastasis development.

We found that short hairpin RNA silencing of B7-H3 reduced the migratory potential as well as the matrigel-invasiveness of the malignant melanoma cells in vitro. In an in vivo experimental metastasis model, silencing of B7-H3 increased the symptom-free survival of nude mice and rats significantly, this in parallel with a lower fraction mice having microscopically detectable metastasis compared to control mice. The brain was the predominant organ with metastases and a clear difference between the nude mice injected with B7-H3 expressing cells and B7-H3 knock down cells was observed, with 10/14 and 6/17 mice having brain tumors, respectively. Furthermore, we found the expression of several metastasis-associated proteins, such as MMP-2, TIMP1 and TIMP2 to be regulated by B7-H3. In addition, the secretion of IL-8 was markedly reduced in the B7-H3 knock down cells as well as the phosphorylation of Stat3. Interestingly, activated Stat3 is known to play a role in brain metastasis.

Taken together, our findings suggest that B7-H3 might be a potential therapeutic target for anti-metastasis therapy in human melanoma.

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 2423. doi:10.1158/1538-7445.AM2011-2423

Disseminated tumour cells as a prognostic biomarker in colorectal cancer

BACKGROUND

The study was performed to determine detection rate and prognostic relevance of disseminated tumour cells (DTC) in patients receiving curatively intended surgery for colorectal cancer (CRC).

METHODS

The study population consisted of 235 patients with CRC prospectively recruited from five hospitals in the Oslo region. Bone marrow (BM) aspirates were collected at the time of surgery and the presence of DTC was determined by two immunological methods; immunomagnetic selection (using an anti-EpCAM antibody) and immunocytochemistry (using a pan-cytokeratin antibody). Associations between the presence of DTC and metastasis-free, disease-specific and overall survival were analysed using univariate and multivariate methods.

RESULTS

Disseminated tumour cells were detected in 41 (17%) and 28 (12%) of the 235 examined BM samples by immunomagnetic selection and immunocytochemistry, respectively, with only five samples being positive with both methods. The presence of DTC was associated with adverse outcome (metastasis-free, disease-specific and overall survival) in univariate and multivariate analyses.

CONCLUSION

The presence of DTC was associated with adverse prognosis in this cohort of patients curatively resected for CRC, suggesting that DTC detection still holds promise as a biomarker in CRC.

Antitumour activity of oral E7080, a novel inhibitor of multiple tyrosine kinases, in human sarcoma xenografts

E7080 is an inhibitor of multiple tyrosine kinases, several of which have pro-angiogenic properties, including receptors for VEGF, FGF, SCF and PDGF. We undertook our study to evaluate the preclinical activity of E7080 in human sarcomas. The antitumour activity of orally administered E7080 was tested in ten human tumour xenografts representing different sarcoma histotypes. Concomitant changes in microvessel density were assayed by immunohistochemistry to CD31. Immunohistochemistry was also used to assess the expression of kinases that E7080 is known to inhibit. The MTS assay was applied to determine effects on tumour cell viability in vitro. At the Q1D5 × 2 schedule, E7080 (30 mg/kg) was active (T/C<40%) in 7/10 xenografts. The effects were accompanied by marked decrease in microvessel densities. Given at the Q1D5 × 4 schedule, E7080 (30, 10, 3 mg/kg) showed antitumour activity in a dose dependent manner in two different xenografts. E7080 growth inhibition did not correlate with the expression of VEGFR1-3, PDGFRA, PDGFRB, FGFR1 or KIT on tumour cells but was significantly correlated with expression of VEGFR2 on tumour microvessels. In vitro E7080 did not show potent effects on tumour cell viability in four different sarcoma cell lines, with IC50 values ≥ 10 μM. In conclusion, E7080 showed broad in vivo antitumour activity in sarcoma, mainly attributable to angiogenesis inhibition. E7080 was also active in xenografts resistant to one or more clinically relevant reference drugs given at MTD (doxorubicin, cisplatin or ifosfamide). The present results encourage further investigation of a potential role of E7080 in sarcoma therapy in the clinic.

MicroRNAs as biomarkers in colorectal cancer

Colorectal cancer is a leading cause of cancer-related morbidity and mortality in the Western world. While improved diagnostic surveillance and treatment strategies involving surgery, chemo-, and radiotherapy have all contributed to earlier detection and improved survival, treatment decisions are still made almost exclusively based on the cancer's clinicopathological stage at diagnosis. Therefore, the search for new biomarkers to facilitate early diagnosis and individualized treatment is particularly warranted. MicroRNAs (miRNAs) are short, noncoding RNAs that regulate gene expression through posttranscriptional interactions with mRNA, thereby potentially leading to a vast range of downstream effects that depend on the target proteins affected. The discovery that miRNAs may act as either oncogenes or tumor suppressors has initiated extensive research in the cancer field, leading to the identification of numerous miRNAs implicated in carcinogenesis and tumor progression. MiRNAs are chemically stable and can thus be detected in a broad range of clinical samples, making these molecules particularly attractive as potential biomarkers in cancer. While the knowledge of miRNA involvement in colorectal cancer biology is less extensive than for other cancer types and several targets with potential biological and clinical relevance have been identified, a significant amount of research is still needed. In this review, we explore the literature regarding the relevance of miRNAs in colorectal cancer, focusing in particular on miRNAs as potential diagnostic, prognostic, and predictive biomarkers.

Abstract 4304: Malignant melanoma cells with aggressive properties are common and not distinguishable by proposed markers for cancer stem cells

In malignant melanoma, conflicting results have been reported regarding the presence of exclusive cells with enhanced aggressive properties, so called cancer stem cells (CSC), raising a doubt whether melanoma follows a CSC model and is hierarchically organized. By characterizing melanoma cells from short-term cell cultures, xenografts and patient biopsies, we aim to collect further evidence either to: i) support the existence of distinct CSC-like subpopulations, or ii) strengthen a notion about the common presence of cells demonstrating aggressive behavior and lack of cellular hierarchy in melanoma. By using individual-cell assays, we have shown that a large fraction (up to 60 %) of random single melanoma cells display high clonogenicity and self-renewal i.e. properties associated with tumorigenic potential. In search for a marker for such clonogenic/tumorigenic cells, we found that melanomas often harbor a large distinct subpopulation with elevated activity of Aldehyde Dehydrogenase (ALDH), a proposed marker for CSC-like cells in some hierarchically organized cancers. Interestingly, ALDH activity in melanoma patient biopsies seemed to correlate to the expression of melanoma-associated-antigen, HMW-MAA, which is linked to tumor progression. Furthermore, in vivo ALDH+ melanoma cells could convert to ALDH−, while the opposite conversion was rare, indicating a certain “cellular hierarchy” with respect to the ALDH phenotype. However, comparison of ALDH+ and ALDH− cells revealed that both subpopulations are highly clonogenic, tumorigenic and resistant to drugs proposed for melanoma therapy, DTIC and HGS-ETR2. This suggests that in malignant melanoma, ALDH, likewise earlier investigated “surface markers” of CSCs, does not distinguish cells with enhanced biological aggressiveness. In conclusion, melanoma cells exhibiting properties linked to aggressive phenotype are common and not restricted to subpopulations expressing proposed “CSC markers”, which contradicts the traditional view of CSCs.

Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend.

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 4304.

Cystatin E/M suppresses legumain activity and invasion of human melanoma

Background

High activity of cysteine proteases such as legumain and the cathepsins have been shown to facilitate growth and invasion of a variety of tumor types. In breast cancer, several recent studies have indicated that loss of the cysteine protease inhibitor cystatin E/M leads to increased growth and metastasis. Although cystatin E/M is normally expressed in the skin, its role in cysteine protease regulation and progression of malignant melanoma has not been studied.

Methods

A panel of various non-melanoma and melanoma cell lines was used. Cystatin E/M and C were analyzed in cell media by immunoblotting and ELISA. Legumain, cathepsin B and L were analyzed in cell lysates by immunoblotting and their enzymatic activities were analyzed by peptide substrates. Two melanoma cell lines lacking detectable secretion of cystatin E/M were transfected with a cystatin E/M expression plasmid (pCST6), and migration and invasiveness were studied by a Matrigel invasion assay.

Results

Cystatin E/M was undetectable in media from all established melanoma cell lines examined, whereas strong immunobands were detected in two of five primary melanoma lines and in two of six lines derived from patients with metastatic disease. Among the four melanoma lines secreting cystatin E/M, the glycosylated form (17 kD) was predominant compared to the non-glycosylated form (14 kD). Legumain, cathepsin B and L were expressed and active in most of the cell lines, although at low levels in the melanomas expressing cystatin E/M. In the melanoma lines where cystatin E/M was secreted, cystatin C was generally absent or expressed at a very low level. When melanoma cells lacking secretion of cystatin E/M were transfected with pCST6, their intracellular legumain activity was significantly inhibited. In contrast, cathepsin B activity was not affected. Furthermore, invasion was suppressed in cystatin E/M over-expressing melanoma cell lines as measured by the transwell Matrigel assay.

Conclusions

These results suggest that the level of cystatin E/M regulates legumain activity and hence the invasive potential of human melanoma cells.

Immunotoxins: a promising treatment modality for metastatic melanoma?

The incidence of melanoma is rising in the Western population, and melanoma is the most aggressive form of skin cancer with a very poor prognosis once it has progressed to metastatic stages. Patients with stage IV melanoma (metastases to distant lymph nodes and other areas of the body) are treated with the chemotherapeutic drug dacarbazine (DTIC). However, fewer than 5% of the patients treated with DTIC sustain long-term complete responses; hence, DTIC is administered with palliative purposes. New therapy is urgently needed. We are developing another therapeutic strategy, specifically targeting melanoma cells with the 9.2.27PE immunotoxin (IT). ITs bind to antigens overexpressed on cancer cells and are therefore tumor selective. This targeted approach may potentially cause fewer side effects in a clinical situation compared to conventional approaches like chemotherapy and radiotherapy.

Immunomagnetic detection of micrometastatic cells in bone marrow in uveal melanoma patients

PURPOSE

Our objective was to introduce immunomagnetic separation (IMS) in ocular research by evaluating the possibility of detecting tumour cells in bone marrow (BM) and peripheral blood (PB) samples and validating the captured cells as melanocytic cells.

METHODS

Mononuclear cell (MNC) fractions isolated from BM and PB in uveal melanoma patients were examined for tumour cells using our IMS method. Sheep-anti-mouse IgG antibody-coated super paramagnetic particles were conjugated to an anti-melanoma antibody. Microscopy of the magnetic fraction isolated from MNCs was performed to identify and count the number of bead-rosetted cells. The finding of at least two rosettes with coated beads in a 20-microl fraction of a sample was registered as a positive test. The melanocytic nature of the tumour cells was ascertained with a double labelling procedure using fluorescent microparticles.

RESULTS

Using IMS in a study of 328 patients, tumour cells were at initial diagnosis found in BM and PB in 29.9% and 1.6% of cases, respectively. In positive samples, a median of 56 tumour cells (range 2-500) were identified. The captured cells were documented to be of melanocytic origin by the simultaneous binding of fluorescent beads coated with another melanoma-associated antibody.

CONCLUSIONS

The IMS method was sensitive and efficient in the detection of occult melanoma tumour cells in BM. The validity of the immunomagnetic technique was strengthened by verifying the melanocytic characteristics of the isolated cells. The IMS procedure identifies intact, vital tumour cells, permitting further molecular characterization, an advantage which makes this method attractive for extended use. The clinical relevance of the findings will be further investigated in follow-up studies with repeated sampling and characterization of the isolated tumour cells.

Synergistic anti-cancer effects of immunotoxin and cyclosporin in vitro and in vivo

BACKGROUND

The clinical use of immunotoxins (ITs) has been hampered by hepatotoxicity, and the induction of a strong human-anti-IT response. The human-anti-IT response results in neutralisation of the immunoconjugates, rendering repetitive treatment inefficacious.

METHODS

We evaluated the combination of cyclosporin A (CsA) with various Pseudomonas exotoxin A-based ITs in human breast, cervical, and prostate cancer cell lines measured by protein synthesis, cell viability, and TUNEL assay. Furthermore, expression of essential proteins were analysed by western blot. We used cervical cancer model in nude rats to evaluate the anti-metastatic effect of the combination. The anti-immunogenic response by the CsA treatment was investigated in immunocompetent rats.

RESULTS

The combination of CsA with ITs caused remarkable synergistic cytotoxicity, in several cancer cell lines, characterised by protein synthesis inhibition, decreased cell viability, and an increased apoptotic index. Furthermore, the combination strongly inhibited formation of metastases in a cervical cancer model in nude rats with a statistically significant increase in median survival time of the combination-treated animals, as compared with those receiving a suboptimal dose of IT alone. Notably, we found in immunocompetent rats that the anti-IT immunoresponse elicited by repeated administration of IT was efficiently abrogated by CsA; notably the antibody responds towards the highly immunogenic PE was shown to be prevented.

CONCLUSION

The combination of ITs and CsA might constitute a significant improvement in the clinical potential of systemic IT treatment of cancer patients.

The melanoma specific 9.2.27PE immunotoxin efficiently kills melanoma cells in vitro

Malignant melanomas are generally drug resistant and have a very poor prognosis. We have studied the effects of a chemical conjugate of pseudomonas exotoxin A (PE) and the antibody 9.2.27, which recognizes the high molecular weight melanoma associated antigen (HMW-MAA) expressed in most malignant melanomas and melanoma cell lines. We demonstrate that the 9.2.27PE immunotoxin (IT) induces cell death in malignant melanoma cells through protein synthesis inhibition followed by some morphological and biochemical features of apoptosis, like rounding up of cells, chromatin condensation and inactivation of PARP. Unlike previous results with the 425.3PE IT in breast cancer cells, we detected no depolarization of the mitochondrial membrane after 9.2.27PE IT treatment. This is likely due to the lack of strong activation of caspase-8 and caspase-3. The lack of depolarization suggests that cytochrome c, a molecule that triggers activation of caspase-3, was retained within the mitochondria. In addition, the protein level of the antiapoptotic Bcl-2 did not decrease in contrast to other antiapoptotic molecules belonging to the inhibitor of apoptosis and the Bcl-2 family. This suggests that Bcl-2 may play a role in maintaining the mitochondrial membrane integrity in the 9.2.27PE-treated cells. Nevertheless, 9.2.27PE IT efficiently killed malignant melanoma cells that can be ascribed to inhibition of protein synthesis followed by some morphological and biochemical features of apoptosis.