Adoptive cell transfer therapy with ex vivo primed peripheral lymphocytes in combination with anti-PDL1 therapy effectively inhibits triple-negative breast cancer growth and metastasis

BACKGROUND

Adoptive cell transfer cancer immunotherapy holds promise for treating disseminated disease, yet generating sufficient numbers of lymphocytes with anti-cancer activity against diverse specificities remains a major challenge. We recently developed a novel procedure (ALECSAT) for selecting, expanding and maturating polyclonal lymphocytes from peripheral blood with the capacity to target malignant cells.

METHODS

Immunodeficient mice were challenged with triple-negative breast cancer cell lines or patient-derived xenografts (PDX) and treated with allogeneic or autologous ALECSAT cells with and without anti-PDL1 therapy to assess the capacity of ALECSAT cells to inhibit primary tumor growth and metastasis.

RESULTS

ALECSAT mono therapy inhibited metastasis, but did not inhibit primary tumor growth or prolong survival of tumor-bearing mice. In contrast, combined ALECSAT and anti-PDL1 therapy significantly inhibited primary tumor growth, nearly completely blocked metastasis, and prolonged survival of tumor-bearing mice.

CONCLUSIONS

Combined ALECSAT and anti-PDL1 therapy results in favorable anti-cancer responses in both cell line-derived xenograft and autologous PDX models of advanced triple-negative breast cancer.

Co-targeting CDK2 and CDK4/6 overcomes resistance to aromatase and CDK4/6 inhibitors in ER+ breast cancer

Resistance to aromatase inhibitor (AI) treatment and combined CDK4/6 inhibitor (CDK4/6i) and endocrine therapy (ET) are crucial clinical challenges in treating estrogen receptor-positive (ER+) breast cancer. Understanding the resistance mechanisms and identifying reliable predictive biomarkers and novel treatment combinations to overcome resistance are urgently needed. Herein, we show that upregulation of CDK6, p-CDK2, and/or cyclin E1 is associated with adaptation and resistance to AI-monotherapy and combined CDK4/6i and ET in ER+ advanced breast cancer. Importantly, co-targeting CDK2 and CDK4/6 with ET synergistically impairs cellular growth, induces cell cycle arrest and apoptosis, and delays progression in AI-resistant and combined CDK4/6i and fulvestrant-resistant cell models and in an AI-resistant autocrine breast tumor in a postmenopausal xenograft model. Analysis of CDK6, p-CDK2, and/or cyclin E1 expression as a combined biomarker in metastatic lesions of ER+ advanced breast cancer patients treated with AI-monotherapy or combined CDK4/6i and ET revealed a correlation between high biomarker expression and shorter progression-free survival (PFS), and the biomarker combination was an independent prognostic factor in both patients cohorts. Our study supports the clinical development of therapeutic strategies co-targeting ER, CDK4/6 and CDK2 following progression on AI-monotherapy or combined CDK4/6i and ET to improve survival of patients exhibiting high tumor levels of CDK6, p-CDK2, and/or cyclin E1.

Targeting two distinct epitopes on human CD73 with a bispecific antibody improves anticancer activity

Background

Immunosuppressive extracellular adenosine is generated by the enzymatic activity of CD73. In preclinical models, antibodies (Abs) targeting different epitopes on CD73 exert anticancer activity through distinct mechanisms such as inhibition of enzymatic activity, engagement of Fc receptors, and spatial redistribution of CD73.

Methods

Using controlled Fab arm exchange, we generated biparatopic bispecific antibodies (bsAbs) from parental anti-CD73 Abs with distinct anticancer activities. The resulting anticancer activity was evaluated using in vitro and in vivo models.

Results

We demonstrate that different anticancer activities can be combined in a biparatopic bsAb. Remarkably, the bsAb significantly improved the enzyme inhibitory activity compared with the parental Abs, which led to neutralization of adenosine-mediated T-cell suppression as demonstrated by proliferation and interferon gamma (IFN-γ) production and prolonged survival of tumor-bearing mice. Additionally, the bsAb caused more efficient internalization of cell surface CD73 and stimulated potent Fc-mediated engagement of human immune effector cells in vitro and in vivo.

Conclusions

Our data collectively demonstrate that complementary anticancer mechanisms of action of distinct anti-CD73 Abs can be combined and enhanced in a biparatopic bsAb. The multiple mechanisms of action and superior activity compared with the monospecific parental Abs make the bsAb a promising candidate for therapeutic targeting of CD73 in cancer. This concept may greatly improve future Ab design.

Sustained compensatory p38 MAPK signaling following treatment with MAPK inhibitors induces the immunosuppressive protein CD73 in cancer: combined targeting could improve outcomes

RAS-MAPK signaling promotes immune evasion and cancer cell survival, and MAPK inhibitors (MAPKis) are frequently used as cancer therapies. Despite progress elucidating the direct effects of MAPKi on immune cells, their indirect effect on the tumor microenvironment (TME) through changes in tumor cells remains incompletely understood. Here, we present evidence of a rapid compensatory response to MAPKi that is driven by sustained p38 MAPK signaling and by which cancer cells can upregulate the immunosuppressive protein CD73 to reduce the antitumor immune response. This compensatory response also results in decreased sensitivity toward MAPKi, and, accordingly, combining anti-CD73 antibodies and MAPKi significantly enhances the antitumor effect compared to single-agent treatment in vivo. Combining MAPKi and anti-CD73 was accompanied by significant alterations in intratumor immune cell composition, supporting the effect of MAPKi-induced CD73 expression on the TME. We show that high CD73 expression significantly correlates with worse outcome in MAPKi-treated colorectal cancer patients, highlighting the potential clinical importance of increased CD73 expression following MAPKi treatment. Our findings may explain the diminished effect of MAPKi in cancer patients and provides further rationale for combined anti-CD73 and MAPKi treatment.

MCM3 upregulation confers endocrine resistance in breast cancer and is a predictive marker of diminished tamoxifen benefit

Resistance to endocrine therapy in estrogen receptor-positive (ER+) breast cancer is a major clinical problem with poorly understood mechanisms. There is an unmet need for prognostic and predictive biomarkers to allow appropriate therapeutic targeting. We evaluated the mechanism by which minichromosome maintenance protein 3 (MCM3) influences endocrine resistance and its predictive/prognostic potential in ER+ breast cancer. We discovered that ER+ breast cancer cells survive tamoxifen and letrozole treatments through upregulation of minichromosome maintenance proteins (MCMs), including MCM3, which are key molecules in the cell cycle and DNA replication. Lowering MCM3 expression in endocrine-resistant cells restored drug sensitivity and altered phosphorylation of cell cycle regulators, including p53(Ser315,33), CHK1(Ser317), and cdc25b(Ser323), suggesting that the interaction of MCM3 with cell cycle proteins is an important mechanism of overcoming replicative stress and anti-proliferative effects of endocrine treatments. Interestingly, the MCM3 levels did not affect the efficacy of growth inhibitory by CDK4/6 inhibitors. Evaluation of MCM3 levels in primary tumors from four independent cohorts of breast cancer patients receiving adjuvant tamoxifen mono-therapy or no adjuvant treatment, including the Stockholm tamoxifen (STO-3) trial, showed MCM3 to be an independent prognostic marker adding information beyond Ki67. In addition, MCM3 was shown to be a predictive marker of response to endocrine treatment. Our study reveals a coordinated signaling network centered around MCM3 that limits response to endocrine therapy in ER+ breast cancer and identifies MCM3 as a clinically useful prognostic and predictive biomarker that allows personalized treatment of ER+ breast cancer patients.

Gene expression alterations associated with outcome in aromatase inhibitor-treated ER+ early-stage breast cancer patients

Aromatase inhibitors (AI), either alone or together with chemotherapy, have become the standard adjuvant treatment for postmenopausal, estrogen receptor-positive (ER+) breast cancer. Although AIs improve overall survival, resistance is still a major clinical problem, thus additional biomarkers predictive of outcome of ER+ breast cancer patients treated with AIs are needed. Global gene expression analysis was performed on ER+ primary breast cancers from patients treated with adjuvant AI monotherapy; half experienced recurrence (median follow-up 6.7 years). Gene expression alterations were validated by qRT-PCR, and functional studies evaluating the effect of siRNA-mediated gene knockdown on cell growth were performed. Twenty-six genes, including TFF3, DACH1, RGS5, and GHR, were shown to exhibit altered expression in tumors from patients with recurrence versus non-recurrent (fold change ≥1.5, p < 0.05), and the gene expression alterations were confirmed using qRT-PCR. Ten of these 26 genes could be linked in a network associated with cellular proliferation, growth, and development. TFF3, which encodes for trefoil factor 3 and is an estrogen-responsive oncogene shown to play a functional role in tamoxifen resistance and metastasis of ER+ breast cancer, was also shown to be upregulated in an AI-resistant cell line model, and reduction of TFF3 levels using TFF3-specific siRNAs decreased the growth of both the AI-resistant and -sensitive parental cell lines. Moreover, overexpression of TFF3 in parental AI-sensitive MCF-7/S0.5 cells resulted in reduced sensitivity to the AI exemestane, whereas TFF3 overexpression had no effect on growth in the absence of exemestane, indicating that TFF3 mediates growth and survival signals that abrogate the growth inhibitory effect of exemestane. We identified a panel of 26 genes exhibiting altered expression associated with disease recurrence in patients treated with adjuvant AI monotherapy, including TFF3, which was shown to exhibit a growth- and survival-promoting effect in the context of AI treatment.

Abstract 1887: Global gene expression analysis of tamoxifen-resistant breast cancer cell lines identified a gene signature predictive of clinical outcome of breast cancer patients treated with endocrine therapy

Objective: Altered gene expression associated with endocrine resistance in breast cancer cell lines may have potential prognostic/predictive values in patients with ER+ breast cancer receiving endocrine therapy. In this study, we investigated mRNA expression profiles associated with the tamoxifen-resistant phenotype using a panel of isogenic MCF-7-based breast cancer cell lines to elucidate the endocrine resistance mechanism and assess whether the pattern of gene expression predicted clinical outcome in breast cancer patients treated with endocrine therapy.

Method: Gene array was performed on a panel of clinically-relevant tamoxifen-resistant breast cancer cell lines (TamR) and their tamoxifen-sensitive parental cell line. Genes that showed significant alteration in expression (FDR 0.01) in TamRs vs parental cell lines were evaluated for their potential to stratify tamoxifen-treated breast cancer patients based on outcome using published gene expression data sets.

Results: Using a testing set consisting of microarray data from 163 ER+ primary breast cancer patients treated with tamoxifen we identified 20 genes among those that showed significant altered expression in TamR that could stratify patients according to clinical outcome. . The potential of this 20-gene signature to stratify patients was further confirmed in 2 independent data sets consisting of ER+ tamoxifen-treated breast cancer patients with a sensitivity and specificity 53% and 79% respectively in the first cohort (N=153), and sensitivity and specificity of 37% and 91% respectively in the second cohort (N=201). Evaluation of relapse-free survival of tamoxifen-treated patients classified by the signature as having bad or good outcomes showed significant differences in time-to-relapse, with median disease-free survival times of 5.1 vs 8.9 years in the first cohort (N=153, p=0.03) and 4.2 vs 7.7 years in the second (N=201, p=0.006).

Conclusions: The expression pattern of the 20-gene signature identified in this study appears to have a strong potential as a biomarker of clinical outcome of endocrine-treated breast cancer patients.

Citation Format: Daniel Elias Roro, Henriette Vever, Anne Lykkesfeldt, Henrik Ditzel. Global gene expression analysis of tamoxifen-resistant breast cancer cell lines identified a gene signature predictive of clinical outcome of breast cancer patients treated with endocrine therapy. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1887. doi:10.1158/1538-7445.AM2014-1887

Gene expression profiling identifies FYN as an important molecule in tamoxifen resistance and a predictor of early recurrence in patients treated with endocrine therapy

To elucidate the molecular mechanisms of tamoxifen resistance in breast cancer, we performed gene array analyses and identified 366 genes with altered expression in four unique tamoxifen-resistant (TamR) cell lines vs the parental tamoxifen-sensitive MCF-7/S0.5 cell line. Most of these genes were functionally linked to cell proliferation, death and control of gene expression, and include FYN, PRKCA, ITPR1, DPYD, DACH1, LYN, GBP1 and PRLR. Treatment with FYN-specific small interfering RNA or a SRC family kinase inhibitor reduced cell growth of TamR cell lines while exerting no significant effect on MCF-7/S0.5 cells. Moreover, overexpression of FYN in parental tamoxifen-sensitive MCF-7/S0.5 cells resulted in reduced sensitivity to tamoxifen treatment, whereas knockdown of FYN in the FYN-overexpressing MCF-7/S0.5 cells restored sensitivity to tamoxifen, demonstrating growth- and survival-promoting function of FYN in MCF-7 cells. FYN knockdown in TamR cells led to reduced phosphorylation of 14-3-3 and Cdc25A, suggesting that FYN, by activation of important cell cycle-associated proteins, may overcome the anti-proliferative effects of tamoxifen. Evaluation of the subcellular localization of FYN in primary breast tumors from two cohorts of endocrine-treated ER+ breast cancer patients, one with advanced disease (N=47) and the other with early disease (N=76), showed that in the former, plasma membrane-associated FYN expression strongly correlated with longer progression-free survival (P<0.0002). Similarly, in early breast cancer patients, membrane-associated expression of FYN in the primary breast tumor was significantly associated with increased metastasis-free (P<0.04) and overall (P<0.004) survival independent of tumor size, grade or lymph node status. Our results indicate that FYN has an important role in tamoxifen resistance, and its subcellular localization in breast tumor cells may be an important novel biomarker of response to endocrine therapy in breast cancer.

Abstract 1190: Gene expression profiling identified FYN as an important gene in tamoxifen resistance and a predictor of early recurrence in patients treated with endocrine therapy

To elucidate the molecular mechanisms of tamoxifen resistance in breast cancer we performed microarray profiling and identified 366 genes with altered expression in 4 tamoxifen-resistant (TamRs) vs. the parental tamoxifen-sensitive MCF-7/S0.5 cell lines. Most of these genes were functionally linked to cell growth, proliferation, death and control of gene expression and included FYN, PRKCα, ITPR1, DPYD, DACH1, GBP1 and PRLR. Increased expression of FYN was observed in TamR cells and treatment with FYN-specific interfering RNA or a specific Src family kinase (SFK) inhibitor restored the anti-proliferative effect of tamoxifen in these cells. TamR cells also expressed increased levels of phosphorylated breast cancer antiestrogen resistance protein 1 (pBCAR1), an important downstream SFK substrate in the MAPK pathway. Evaluation of the association of subcellular localization of FYN in cancer tissue and clinical endpoints was made in 2 cohorts of ER+ breast cancer patients, one with advanced disease (N=47) and the other with early breast cancer (N=76). The result showed that plasma membrane-associated FYN expression in the cancer cells strongly correlated with longer progression-free survival compared to FYN expression not associated with the plasma membrane (p&lt;0.0002) in the advanced disease cohort. Similarly, in the early breast cancer patients, plasma membrane associated FYN expression was associated with longer metastasis-free survival (p&lt;0.003) and overall survival (p&lt;0.0005) independent of tumor size, grade and node status. Our results indicate that FYN plays an important role in tamoxifen resistance, and its subcellular location in breast tumor cells may be an important novel biomarker of response to endocrine therapy in breast cancer.

Citation Format: Daniel Elias Roro, Henriette Vever, Henrik Ditzel. Gene expression profiling identified FYN as an important gene in tamoxifen resistance and a predictor of early recurrence in patients treated with endocrine therapy . [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 1190. doi:10.1158/1538-7445.AM2013-1190