Minimal Residual Disease Status Predicts Outcome in Patients With Previously Untreated Follicular Lymphoma: A Prospective Analysis of the Phase III GALLIUM Study

PURPOSE

We report an analysis of minimal residual/detectable disease (MRD) as a predictor of outcome in previously untreated patients with follicular lymphoma (FL) from the randomized, multicenter GALLIUM (ClinicalTrials.gov identifier: NCT01332968) trial.

PATIENTS AND METHODS

Patients received induction with obinutuzumab (G) or rituximab (R) plus bendamustine, or cyclophosphamide, doxorubicin, vincristine, prednisone (CHOP) or cyclophosphamide, vincristine, prednisone (CVP) chemotherapy, followed by maintenance with the same antibody in responders. MRD status was assessed at predefined time points (mid-induction [MI], end of induction [EOI], and at 4-6 monthly intervals during maintenance and follow-up). Patients with evaluable biomarker data at diagnosis were included in the survival analysis.

RESULTS

MRD positivity was associated with inferior progression-free survival (PFS) at MI (hazard ratio [HR], 3.03 [95% CI, 2.07 to 4.45]; P < .0001) and EOI (HR, 2.25 [95% CI, 1.53 to 3.32]; P < .0001). MRD response was higher after G- versus R-chemotherapy at MI (94.2% v 88.9%; P = .013) and at EOI (93.1% v 86.7%; P = .0077). Late responders (MI-positive/EOI-negative) had a significantly poorer PFS than early responders (MI-negative/EOI-negative; HR, 3.11 [95% CI, 1.75 to 5.52]; P = .00011). The smallest proportion of MRD positivity was observed in patients receiving bendamustine at MI (4.8% v 16.0% in those receiving CHOP; P < .0001). G appeared to compensate for less effective chemotherapy regimens, with similar MRD response rates observed across the G-chemo groups. During the maintenance period, more patients treated with R than with G were MRD-positive (R-CHOP, 20.7% v G-CHOP, 7.0%; R-CVP, 21.7% v G-CVP, 9.4%). Throughout maintenance, MRD positivity was associated with clinical relapse.

CONCLUSION

MRD status can determine outcome after induction and during maintenance, and MRD negativity is a prerequisite for long-term disease control in FL. The higher MRD responses after G- versus R-based treatment confirm more effective tumor cell clearance.

NGS-determined molecular markers and disease burden metrics from ctDNA correlate with PFS in previously untreated DLBCL

Personalized risk stratification and treatment may help improve outcomes among patients with diffuse large B-cell lymphoma (DLBCL). We developed a next-generation sequencing (NGS)-based method to assess a range of potential prognostic indicators, and evaluated it using pretreatment plasma samples from 310 patients with previously untreated DLBCL from the GOYA trial (NCT01287741). Variant calls and DLBCL subtyping with the plasma-based method were concordant with corresponding tissue-based methods. Patients with a tumor burden greater than the median (p = .003) and non-germinal center B-cell-like (non-GCB) DLBCL (p = .049) had worse progression-free survival than patients with a tumor burden less than the median or GCB DLBCL. Multi-factor assessment combining orthogonal features from a single pretreatment plasma sample has promise as a prognostic indicator in this setting (p = .085). This minimally invasive plasma-based NGS assay could enable comprehensive prognostic assessment of patients in a clinical setting, with greater accessibility than current methods.

Patterns of Oncogene Coexpression at Single-Cell Resolution Influence Survival in Lymphoma

Cancers often overexpress multiple clinically relevant oncogenes, but it is not known if combinations of oncogenes in cellular subpopulations within a cancer influence clinical outcomes. Using quantitative multispectral imaging of the prognostically relevant oncogenes MYC, BCL2, and BCL6 in diffuse large B-cell lymphoma (DLBCL), we show that the percentage of cells with a unique combination MYC+BCL2+BCL6- (M+2+6-) consistently predicts survival across four independent cohorts (n = 449), an effect not observed with other combinations including M+2+6+. We show that the M+2+6- percentage can be mathematically derived from quantitative measurements of the individual oncogenes and correlates with survival in IHC (n = 316) and gene expression (n = 2,521) datasets. Comparative bulk/single-cell transcriptomic analyses of DLBCL samples and MYC/BCL2/BCL6-transformed primary B cells identify molecular features, including cyclin D2 and PI3K/AKT as candidate regulators of M+2+6- unfavorable biology. Similar analyses evaluating oncogenic combinations at single-cell resolution in other cancers may facilitate an understanding of cancer evolution and therapy resistance.

SIGNIFICANCE

Using single-cell-resolved multiplexed imaging, we show that selected subpopulations of cells expressing specific combinations of oncogenes influence clinical outcomes in lymphoma. We describe a probabilistic metric for the estimation of cellular oncogenic coexpression from IHC or bulk transcriptomes, with possible implications for prognostication and therapeutic target discovery in cancer. This article is highlighted in the In This Issue feature, p. 1027.

Baseline Total Metabolic Tumor Volume is Prognostic for Refractoriness to Immunochemotherapy in DLBCL: Results From GOYA

INTRODUCTION

A good response to initial therapy is key to maximizing survival in patients with diffuse large B-cell lymphoma (DLBCL), but patients with chemorefractory disease and early progression have poor outcomes.

PATIENTS AND METHODS

Data from the GOYA study in patients with DLBCL who received first-line rituximab or obinutuzumab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) were analyzed. Positron emission tomography/computed tomography (PET/CT)-derived characteristics associated with total metabolic tumor volume (TMTV) and clinical risk factors for primary chemorefractory disease and disease progression within 12 months (POD12) were explored.

RESULTS

Of those patients fulfilling the criteria for analysis, 108/1126 (10%) were primary chemorefractory and 147/1106 (13%) had POD12. Primary chemorefractory and POD12 status were strongly associated with reduced overall survival. After multivariable analysis of clinical and imaging-based risk factors by backward elimination, only very high TMTV (quartile [Q] 1 vs. Q4 odds ratio [OR]: 0.45; P = .006) and serum albumin levels (low vs. normal OR of 1.86; P = .004) were associated with primary chemorefractoriness. After additionally accounting for BCL2/MYC translocation in a subset of patients, TMTV and BCL2/MYC double-hit status remained as significant predictors of primary chemorefractoriness (Q1 vs. Q4 OR: 0.32, P = .01 and double-hit vs. no-hit OR of 4.47, P = .02, respectively). Risk factors including very high TMTV, high sum of the product of the longest diameters (SPD), geographic region (Asia), short time since diagnosis, extranodal involvement and low serum albumin were retained for POD12.

CONCLUSION

PET-derived TMTV has prognostic value in identifying patients at risk of early treatment failure.

CELESTIMO: A phase III trial evaluating the efficacy and safety of mosunetuzumab plus lenalidomide versus rituximab plus lenalidomide in patients with relapsed or refractory follicular lymphoma who have received ≥ 1 line of systemic therapy

TPS7588

Background: Despite significant progress with first-line immunochemotherapy, most patients with follicular lymphoma (FL) will eventually relapse with increasing refractoriness and decreasing duration of response to subsequent therapy lines (Rivas-Delgado et al. 2019). Mosunetuzumab (M) is a CD20xCD3 bispecific antibody that engages and redirects T-cells to eliminate malignant B cells (Sun et al. 2015). In an ongoing, pivotal Phase I/II trial of M monotherapy, patients with relapsed/refractory (R/R) FL who have received ≥2 prior treatment lines achieve deep and durable responses (NCT02500407; Budde et al. ASH 2021). Preliminary data from a Phase Ib study have suggested favorable safety and promising activity of M in combination with lenalidomide (Len), a potent immunomodulatory agent that has shown additive/synergistic activity with an anti-CD20 antibody in R/R indolent lymphoma (Leonard et al. 2019), in patients with R/R FL who have received ≥1 prior therapy (NCT04246086; Morschhauser et al. ASH 2021). The chemotherapy-free M-Len combination may represent a promising outpatient therapy option for future management of patients with R/R FL. The randomized, multicenter Phase III study has been initiated. Methods: CELESTIMO (NCT04712097) is a randomized, multicenter, open-label Phase III study evaluating the efficacy and safety of M-Len versus rituximab plus Len (R-Len) in patients with previously treated R/R FL. Patients must have histologically documented CD20+ FL (Grades 1–3a) requiring systemic therapy and have received ≥1 prior line of systemic therapy. Patients are randomized (1:1) to receive M-Len (M intravenously [IV] on Days [D] 1, 8 and 15 of Cycle [C] 1 [21-day cycle] and D1 of C2–12 [28-day cycles], plus Len orally [PO] on D1–21 of C2–12) or R-Len (R IV on D1, 8, 15 and 22 of C1 then on D1 of C3, 5, 7, 9, and 11, plus Len PO on D1–21 of C1–12 [all 28-day cycles]), and stratified by disease progression within 24 months of initial treatment (yes/no), number of prior lines of therapy (1 versus ≥2), and refractoriness to anti-CD20 therapy (refractory/non-refractory). The primary endpoint is progression-free survival (PFS) assessed by independent review committee; secondary endpoints include investigator-assessed PFS, complete and objective response, overall survival, and safety. Biomarkers predictive of response to M-Len and R-Len will also be investigated as exploratory endpoints. The study started recruitment in 2021 and plans to enroll ̃400 patients from approximately 16 countries and 150 sites globally. Clinical trial information: NCT04712097.

Patient-reported outcomes provide prognostic information for survival in patients with diffuse large B-cell lymphoma: Analysis of 1239 patients from the GOYA study

Purpose

We investigated the prognostic value of pretreatment patient‐reported outcomes (PROs) in patients with diffuse large B‐cell lymphoma (DLBCL) receiving obinutuzumab/rituximab plus chemotherapy in the GOYA phase III study.

Methods

Patients completed the European Organization for Research and Treatment of Cancer Quality of Life (EORTC QLQ‐C30) and the Functional assessment of chronic illness therapy‐Lymphoma (FACT–Lym) lymphoma subscale (LYMS) during the study. PRO scales with high prognostic value were identified through Cox regression analyses of overall survival (OS) and progression‐free survival (PFS). These scales were evaluated in terms of their additional prognostic value beyond the International Prognostic Index (IPI). A preliminary assessment was performed to evaluate whether the scales provided improved patient‐risk stratification beyond IPI.

Results

One thousand two hundred and fifty‐nine patients with valid pretreatment PRO scales were included in the analyses, and complete pretreatment data were available for 1239/1414 patients (87.6%). Four PRO scales with high prognostic value were identified: FACT–Lym LYMS and EORTC QLQ‐C30 physical functioning, global health status/quality of life (QoL), and fatigue. All four scales retained significant prognostic value for OS and PFS after IPI adjustment (all p < 0.05). After adjusting for multiple clinical variables (IPI, cell of origin, BCL2 status, and total metabolic tumor volume), all four scales retained significant prognostic value (all p < 0.05) for OS. Only the EORTC QLQ‐C30 physical functioning scale was significant (p < 0.05) for PFS after adjustment for multiple clinical variables.

Conclusions

In this large population of patients with DLBCL, pretreatment PROs provided prognostic information for OS and PFS beyond the well‐established IPI.

A phase-II study of atezolizumab in combination with obinutuzumab or rituximab for relapsed or refractory mantle cell or marginal zone lymphoma or Waldenström's macroglobulinemia

We report efficacy, safety and biomarker data from a phase-II study evaluating atezolizumab (eight 21-day cycle as induction therapy) in combination with obinutuzumab in patients with relapsed/refractory mantle cell lymphoma (MCL, n = 30) or Waldenström's macroglobulinemia (WM, n = 4), and in combination with rituximab in patients with marginal zone lymphoma (MZL, n = 21). All patients received atezolizumab monotherapy as maintenance for ≤10 cycles. Objective response rates at end of induction were 16.7% (MCL) and 42.9% (MZL), with no responses in WM. Median duration of response was 6.8 months (range 5.7-not estimable) for MCL and not reached for MZL. Treatment-emergent adverse events (TEAEs) occurred in 93.3%, 95.2% and 100% of MCL, MZL and WM patients, respectively. One fatal TEAE (pneumonia) occurred in each of the MCL and MZL groups. Biomarker analysis highlighted the importance of characterizing the immune environment to optimize efficacy of immunotherapy regimens.Trial registration details: EudraCT: 2016-003579-22.

Cellular immunotherapy with multiple infusions of in vitro-expanded haploidentical natural killer cells after autologous transplantation for patients with plasma cell myeloma

BACKGROUND AIMS

To investigate the feasibility and safety of haploidentical natural killer (NK) cell infusions as consolidation immunotherapy after autologous stem cell transplant (ASCT) in patients with plasma cell myeloma.

METHODS

Ten patients (median age, 59 years) received induction treatment followed by high-dose melphalan (200 mg/m²) at day -1, ASCT at day 0 and increasing NK cell doses (1.5 × 10⁶, 1.5 × 10⁷ and multiple doses of 1.0 × 10⁸ cells/kg body weight) from day +1 to day +30 after ASCT. NK cells were harvested and purified from peripheral blood of haploidentical donors and expanded for 19 days with interleukin (IL)-2 and IL-15 under Good Manufacturing Practice conditions.

RESULTS

NK cell numbers increased 56.0-fold (37.4- to 75.5-fold). Patients received a median of 3.8 × 10⁸ (0.9-5.7 × 10⁸) NK cells/kg body weight in six (three to eight) infusions. Multiparametric mass cytometry analysis demonstrated an altered surface receptor repertoire of expanded NK cells with increased degranulation and cytokine production activities but diminished expression of perforin. Donor NK cells were detectable in the peripheral blood, peaking 1 h after each dose (up to 90% donor NK cells). The treatment was safe and well tolerated, without evidence of graft-versus-host disease. Comparison with a control patient population receiving ASCT without NK cell infusions showed no significant difference in relapse, progression-free survival and overall survival.

CONCLUSIONS

This study demonstrates reliable manufacturing of high numbers of activated NK cells for multiple-dose infusions and safe administration of these cellular products. The trial was registered at ClinicalTrials.gov (identifier no. NCT01040026).

Decreased NK-cell tumour immunosurveillance consequent to JAK inhibition enhances metastasis in breast cancer models

The JAK/STAT pathway is an attractive target for breast cancer therapy due to its frequent activation, and clinical trials evaluating JAK inhibitors (JAKi) in advanced breast cancer are ongoing. Using patient biopsies and preclinical models of breast cancer, we demonstrate that the JAK/STAT pathway is active in metastasis. Unexpectedly, blocking the pathway with JAKi enhances the metastatic burden in experimental and orthotopic models of breast cancer metastasis. We demonstrate that this prometastatic effect is due to the immunosuppressive activity of JAKi with ensuing impairment of NK-cell-mediated anti-tumour immunity. Furthermore, we show that immunostimulation with IL-15 overcomes the enhancing effect of JAKi on metastasis formation. Our findings highlight the importance of evaluating the effect of targeted therapy on the tumour environment. The impact of JAKi on NK cells and the potential value of immunostimulators to overcome the weakened tumour immunosurveillance, are worthwhile considering in the clinical setting of breast cancer.

JAK inhibitors are currently undergoing evaluation in clinical trials for advanced breast cancer. Here, the authors show that JAK pathway inhibition increases metastasis in mouse models of breast cancer by impairing NK anti-tumour activity and that these side effects can be overcome by addition of IL-15.

Abstract LB-013: The immunomodulatory effect of JAK inhibitors enhances metastasis by impairing antitumor immunity in preclinical models of breast cancer

The JAK-STAT pathway is an attractive therapeutic target in breast cancer due to its frequent activation. Clinical trials testing JAK inhibitors in breast cancer are ongoing, making it important to understand the effect of this therapeutic approach on metastasis. While it is recognized that tumor growth in primary and metastatic sites is influenced by the local environment, little is known about the effect of targeted therapies on metastases or on host cells interacting with tumor cells at distant locations. Our goal was to determine the effect of JAK inhibitors on breast cancer in the bone environment, a common site of metastasis. Using patient biopsies and preclinical models of breast cancer metastasis, we demonstrate that the JAK-STAT pathway is active in bone metastasis, both in the cancer cells and in the tumor environment. To study the effect of JAK inhibitors, we established preclinical models of bone metastatic tumors, taking advantage of the bone tropism when injected via the intracardiac route, of the breast cancer cell lines, human MDA-MB231 scp1833 and mouse EO771. In vivo, in both models, STAT3 was active and treatment with the JAK1-JAK2 inhibitor ruxolitinib decreased pSTAT3 levels in primary tumors and in bone metastases. Unexpectedly, blocking the pathway with ruxolitinib, or with the JAK2 inhibitor BSK805, enhanced the metastatic burden in both models. To investigate the effect of JAK inhibition on tumor cell dissemination from the primary site, we employed the 4T1.2 model, which spontaneously metastasizes from the mammary tumor to the bone and the lungs. As seen with the other models, there was a significant increase in tumor cell numbers in the bone and in the lungs in response to JAK inhibitor treatment. To understand the mechanism underlying the increase in metastatic load, we considered the host immune system as a potential bystander target of the JAK inhibitors. Indeed, in response to JAK inhibitor treatment we observed a major reduction in the NK cell population. The effect of JAK inhibitors on NK cells was systemic since they were also reduced in the bone marrow and in the peripheral blood of tumor-bearing mice. To mechanistically explain the impact of JAK inhibitors on NK cells, we used the NK cell line, NK-92. Upon treatment of NK-92 cells with JAK inhibitors, activation of multiple STATs decreased and cell proliferation was strongly inhibited. In cytotoxic assays, treatment with JAK inhibitors significantly decreased the killing ability of NK-92 cells against carcinoma cells. To test the in vivo relevance of NK cells in metastatic growth we used NSG mice, which are devoid of NK cell activity. Remarkably, in contrast to the results obtained with 4T1.2 mammary tumors grown in immunocompetent hosts, no increase in bone or lung metastases was observed in tumor-bearing NSG hosts treated with ruxolitinib, providing strong evidence that JAK inhibition increases metastasis by interfering with NK cell mediated anti-tumor innate immunity. These results suggest that the immunomodulatory effect of JAK inhibitors in breast cancer patients undergoing clinical trials should be monitored. Moreover, our work highlights the importance of evaluating the effect of targeted therapy on cell populations in the tumor environment in order to predict and overcame bystander effects that might impact on therapy response.

Citation Format: Nancy E. Hynes, Alessia Bottos, Jason Gill, Thomas Radimerski, Alexander Tzankov, Aleksandra Wodnar-Filipowicz. The immunomodulatory effect of JAK inhibitors enhances metastasis by impairing antitumor immunity in preclinical models of breast cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr LB-013. doi:10.1158/1538-7445.AM2015-LB-013

Abstract P1-07-19: Effects of JAK pathway inhibition in pre-clinical models of breast cancer bone marrow metastases

Bone marrow (BM) metastases are an important problem in metastatic breast cancer. Metastatic-relapse occurs even decades after the first diagnosis and can show different clinical features compared to the primary disease. The cross-talk between cancer cells and the microenvironment influences tumor behaviour and impinges on therapeutic efficiency.

To uncover new targets for the inhibition of BM metastases, we performed a transcriptional analysis of BM stromal cells using in-vivo models of breast cancer bone metastases. We identified IL6, and its downstream JAK kinases pathway, as major up-regulated signals in the bone stroma of tumor-bearing mice. Moreover, we found that a significant proportion of BM metastases from breast cancer patient biopsies are positive for pSTAT3 staining, attesting to activation of JAK-STAT signaling. These results provide a rational to investigate the therapeutic potential of a JAK inhibition in bone metastases. We evaluated the effect of two JAK inhibitors: the BSK805, a JAK2 inhibitor, and ruxolitinib a JAK1-JAK2 inhibitor currently in clinical trials for metastatic breast cancer. In pre-clinical models of breast cancer metastases (the triple negative MDA-MB231 SCP1833 and the ER+ EO771), treatment with the JAK inhibitors decreased pSTAT3 signaling in the bone, but surprisingly increased metastastic tumor burden.

Considering the importance of the JAK-STAT pathway as a therapeutic target, we are investigating the possible bystander effects of blocking JAK kinases. Analysis of the BM stoma showed that JAK inhibition decreased TRAP+ osteoclasts and affected the mesenchymal compartment, with a significant increase in the BM fat compartment in tumor-bearing animals. The reasons for and the consequences of these changes in the bone stroma are under investigation. As the JAK-STAT signaling pathway is also a key regulator of the hematopoietic compartment, we are studying how JAK inhibitors influence the immune response in tumor bearing mice. Further dissection of the immunomodulatory effect of JAK inhibition and how this influences tumor dissemination and expansion is warranted.

Citation Format: Alessia Bottos, Jason Gill, Thomas Radimerski, Alexandar Tzankov, Aleksandra Wodnar-Filipowicz, Nancy E Hynes. Effects of JAK pathway inhibition in pre-clinical models of breast cancer bone marrow metastases [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P1-07-19.

Transcriptional regulation of tenascin-W by TGF-beta signaling in the bone metastatic niche of breast cancer cells

Tenascin‐W is a matricellular protein with a dynamically changing expression pattern in development and disease. In adults, tenascin‐W is mostly restricted to stem cell niches, and is also expressed in the stroma of solid cancers. Here, we analyzed its expression in the bone microenvironment of breast cancer metastasis. Osteoblasts were isolated from tumor‐free or tumor‐bearing bones of mice injected with MDA‐MB231‐1833 breast cancer cells. We found a fourfold upregulation of tenascin‐W in the osteoblast population of tumor‐bearing mice compared to healthy mice, indicating that tenascin‐W is supplied by the bone metastatic niche. Transwell and co‐culture studies showed that human bone marrow stromal cells (BMSCs) express tenascin‐W protein after exposure to factors secreted by MDA‐MB231‐1833 breast cancer cells. To study tenascin‐W gene regulation, we identified and analyzed the tenascin‐W promoter as well as three evolutionary conserved regions in the first intron. 5′RACE analysis of mRNA from human breast cancer, glioblastoma and bone tissue showed a single tenascin‐W transcript with a transcription start site at a noncoding first exon followed by exon 2 containing the ATG translation start. Site‐directed mutagenesis of a SMAD4‐binding element in proximity of the TATA box strongly impaired promoter activity. TGFβ1 induced tenascin‐W expression in human BMSCs through activation of the TGFβ1 receptor ALK5, while glucocorticoids were inhibitory. Our experiments show that tenascin‐W acts as a niche component for breast cancer metastasis to bone by supporting cell migration and cell proliferation of the cancer cells.

What's new?

Once breast cancer metastasizes, it is generally incurable. Proteins in the extracellular matrix play a crucial role in launching the tumor cells to a new site. These authors investigated one such protein, tenascin‐W, which can be found surrounding not only tumor cells but also in bone tissue. Among other things, they studied how breast cancer cells affected tenascin‐W expression. The tumor cells induced bone marrow stromal cells to make more tenascin‐W, suggesting that the protein may pave the way for the cancer to spread to the bone.

Neuroligin 1 induces blood vessel maturation by cooperating with the α6 integrin

The synaptic protein Neuroligin 1 (NLGN1), a cell adhesion molecule, is critical for the formation and consolidation of synaptic connectivity and is involved in vascular development. The mechanism through which NLGN1 acts, especially in vascular cells, is unknown. Here, we aimed at deepening our knowledge on the cellular activities and molecular pathways exploited by endothelial NLGN1 both in vitro and in vivo. We analyzed the phenotypic consequences of NLGN1 expression modulation in endothelial cells through in vitro angiogenesis assays and the mouse postnatal retinal angiogenesis model. We demonstrate that NLGN1, whereas not affecting endothelial cell proliferation or migration, modulates cell adhesion to the vessel stabilizing protein laminin through cooperation with the α6 integrin, a specific laminin receptor. Finally, we show that in vivo, NLGN1 and α6 integrin preferentially colocalize in the mature retinal vessels, whereas NLGN1 deletion causes an aberrant VE-cadherin, laminin and α6 integrin distribution in vessels, along with significant structural defects in the vascular tree.

Memo has a novel role in S1P signaling and is [corrected] crucial for vascular development

Memo is a conserved protein that was identified as an essential mediator of tumor cell motility induced by receptor tyrosine kinase activation. Here we show that Memo null mouse embryonic fibroblasts (MEFs) are impaired in PDGF-induced migration and this is due to a defect in sphingosine-1-phosphate (S1P) signaling. S1P is a bioactive phospholipid produced in response to multiple stimuli, which regulates many cellular processes. S1P is secreted to the extracellular milieu where it exerts its function by binding a family of G-protein coupled receptors (S1PRs), causing their activation in an autocrine or paracrine manner. The process, termed cell-autonomous S1PR signaling, plays a role in survival and migration. Indeed, PDGF uses cell-autonomous S1PR signaling to promote cell migration; we show here that this S1P pathway requires Memo. Using vascular endothelial cells (HUVECs) with Memo knock-down we show that their survival in conditions of serum-starvation is impaired. Furthermore, Memo loss in HUVECs causes a reduction of junctional VE-cadherin and an increase in sprout formation. Each of these phenotypes is rescued by S1P or S1P agonist addition, showing that Memo also plays an important role in cell-autonomous S1PR signaling in endothelial cells. We also produced conventional and endothelial cell-specific conditional Memo knock-out mouse strains and show that Memo is essential for embryonic development. Starting at E13.5 embryos of both strains display bleeding and other vascular problems, some of the phenotypes that have been described in mouse strains lacking S1PRs. The essential role of Memo in embryonic vascular development may be due in part to alterations in S1P signaling. Taken together our results show that Memo has a novel role in the S1P pathway and that Memo is needed to promote cell-autonomous S1PR activation.

Oncogenes and angiogenesis: a way to personalize anti-angiogenic therapy?

The acquisition of oncogenic mutations and promotion of angiogenesis are key hallmarks of cancer. These features are often thought of as separate events in tumor progression and the two fields of research have frequently been considered as independent. However, as we highlight in this review, activated oncogenes and deregulated angiogenesis are tightly associated, as mutations in cancer cells can lead to perturbation of the pro- and anti-angiogenic balance thereby causing aberrant angiogenesis. We propose that normalization of the vascular network by targeting oncogenes in the tumor cells might lead to more efficient and sustained therapeutic effects compared to therapies targeting tumor vessels. We discuss how pharmacological inhibition of oncogenes in tumor cells restores a functional vasculature by bystander anti-angiogenic effect. As genetic alterations are tumor-specific, targeted therapy, which potentially blocks the angiogenic program activated by individual oncogenes may lead to personalized anti-angiogenic therapy.

Abstract 1479: Targeting breast cancer bone metastases looking at the cross-talk between tumor cells and bone environment

Metastatic dissemination is a major cause of cancer associated death; in breast cancer, bone, lung and brain are the major sites of tumor relapse. Bone marrow (BM) is a reservoir for metastatic breast cancer cells that can enter into a quiescent state and remain latent even for decades after dissemination. By still unknown mechanisms, dormant tumor cells can reacquire proliferative ability, thereby causing osteolytic or osteoblastic lesions. During these processes BM environment and tumor cells strongly influence each other. We aimed to analyze molecular mechanisms involved in the liaison between tumor cells and BM microenvironment. More specifically, we investigated how breast cancer cells can affect BM stoma when they home to the endosteal niche and how bone microenvironment can influence the behavior of tumor cells. We took advantage of the MDA-MB231 SCP1833 subclone, which after intracardiac injection has a high propensity for bone metastases. Tumor cell dissemination was followed by bioluminescence imaging and when BM metastases were detected different cell populations from the bone environment were isolated by cell sorting. We excluded cells of the hematopoietic compartment from the analysis, concentrating on the CD45- population. We used the best available antibodies that define osteoblast (CD45-, TR119-, Sca1-, CD51+), endothelial cells (CD45-, TR119-, Sca1+, CD31+) and mesenchymal progenitors (CD45-, TR119-, CD31-, Sca1+) for sorting in order to compare BM populations from tumor-bearing mice with un-injected control mice by a genome wide-transcriptome study. Microarray analysis revealed that BM is strongly affected by breast cancer cell dissemination. Indeed, several components of key molecular pathways involved in tumor development (including TGFBR, PDGFRB, EGFR, HGFR and IGFR signaling pathways) are modulated in the BM of mice with tumor cells. We are following up this analysis by testing the effects of the PI3K-mTOR inhibitor BEZ-235 in breast cancer bone metastases. PIK3CA, that is a downstream effector of several of the above-mentioned pathways, is up-regulated in the bone stroma of tumor-bearing mice. Besides the effect of BEZ-235 on tumor cells, we want to elucidate how the BM responds to PI3K pathway inhibition, and how this influences survival and proliferation of tumor cells. To investigate the effect of BM environment on disseminated tumor cells, we compared the expression profile of MDA-MB231 SCP1833 from the mammary fad pad, i.e, the primary tumor, with tumor cells isolated from BM. We have uncovered some transcripts for surface proteins whose expression is down-regulated in cancer cells that have homed to the BM, compared to tumor cells growing in the mammary fad pad. These and other results that will be presented show the important role that the environment plays on the tumor cell transcriptome and ultimately on the response to therapy.

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 1479. doi:1538-7445.AM2012-1479

Abstract C213: Sorafenib blocks tumor growth, angiogenesis, and metastatic potential in preclinical models of osteosarcoma through the inhibition of ERK1/2, MCL-1, and ezrin pathways

Osteosarcoma (OS) is the most common primary bone tumor in children and young adults. Despite improved prognosis, metastatic or relapsed OS remains largely incurable and no significant improvement has been observed in the last 20 years. Therefore, the search for alternative agents in OS is mandatory.

We explored phospho-ERK 1/2, MCL-1, phospho-Ezrin/Radixin/Moesin (P-ERM) as potential therapeutic targets. The activation of these pathways was shown by immunohistochemistry in about 70% of cases and in all OS cell lines analyzed. Mutational analysis revealed no activating mutations in KRAS. While, BRAF gene was found mutated in 4/30 OS samples from patients. Based on these results we tested the multikinases inhibitor sorafenib (BAY 43-9006) in preclinical models of OS. Sorafenib inhibited OS cell lines proliferation, induced apoptosis and downregulated P-ERK1/2, MCL-1, P-ERM in a dose dependent manner. ERM dephosphorylation is not due to ERK inhibition. The downregulation of MCL-1 increased apoptosis in OS cell lines. In chick embryo chorioallantoic membrane the angiogenesis induced by OS supernatants was blocked by sorafenib treatments. Indeed, sorafenib reduced VEGF and MMP2 production. Sorafenib treatment dramatically reduced tumor volume of OS xenografts and lung metastasis in SCID mice.

In conclusion, ERK1/2, MCL-1 and ERM pathways are active in OS. Sorafenib is able to interrupt their routes in vitro and in vivo displaying antitumoral activity, antiangiogenic effect and reducing metastasis colonies formation in lungs. These data support the testing of sorafenib as a potential therapeutic option in metastatic or relapsed OS patients failing standard treatments.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C213.

Sorafenib blocks tumour growth, angiogenesis and metastatic potential in preclinical models of osteosarcoma through a mechanism potentially involving the inhibition of ERK1/2, MCL-1 and ezrin pathways

BACKGROUND

Osteosarcoma (OS) is the most common primary bone tumour in children and young adults. Despite improved prognosis, metastatic or relapsed OS remains largely incurable and no significant improvement has been observed in the last 20 years. Therefore, the search for alternative agents in OS is mandatory.

RESULTS

We investigated phospho-ERK 1/2, MCL-1, and phospho-Ezrin/Radixin/Moesin (P-ERM) as potential therapeutic targets in OS. Activation of these pathways was shown by immunohistochemistry in about 70% of cases and in all OS cell lines analyzed. Mutational analysis revealed no activating mutations in KRAS whereas BRAF gene was found to be mutated in 4/30 OS samples from patients. Based on these results we tested the multi-kinase inhibitor sorafenib (BAY 43-9006) in preclinical models of OS. Sorafenib inhibited OS cell line proliferation, induced apoptosis and downregulated P-ERK1/2, MCL-1, and P-ERM in a dose-dependent manner. The dephosphorylation of ERM was not due to ERK inhibition. The downregulation of MCL-1 led to an increase in apoptosis in OS cell lines. In chick embryo chorioallantoic membranes, OS supernatants induced angiogenesis, which was blocked by sorafenib and it was also shown that sorafenib reduced VEGF and MMP2 production. In addition, sorafenib treatment dramatically reduced tumour volume of OS xenografts and lung metastasis in SCID mice.

CONCLUSION

In conclusion, ERK1/2, MCL-1 and ERM pathways are shown to be active in OS. Sorafenib is able to inhibit their signal transduction, both in vitro and in vivo, displaying anti-tumoural activity, anti-angiogenic effects, and reducing metastatic colony formation in lungs. These data support the testing of sorafenib as a potential therapeutic option in metastatic or relapsed OS patients unresponsive to standard treatments.