- Email: [email protected]
CCR5 at the Tumor-Stroma Interface
Cancer Cell
Previews Interfering with CCL5/CCR5 at the Tumor-Stroma Interface Vincenzo Bronte1,* and Emilio Bria2 1Immunology,
Department of Medicine, Verona University Hospital, Verona 37134, Italy Oncology, Department of Medicine, Verona University Hospital, Verona 37134, Italy *Correspondence: [email protected] http://dx.doi.org/10.1016/j.ccell.2016.03.019 2Medical
In this issue of Cancer Cell, Halama et al. (2016) further advance chemokine interference as a therapeutic option for cancer by demonstrating the effect of CCR5 blockade in reshaping macrophage polarization toward an anti-tumor functional state in patient-derived tumor models and liver metastases of colorectal cancer patients. During the last two years, the introduction of immune checkpoint inhibitors has reshaped the current standard of care for melanoma and non-small-cell lung cancer (NSCLC) patients. The development of monoclonal antibodies (mAbs) that interfere with the crosstalk between immune and cancer cells, particularly with the PD-1/PD-L1 blockade, has provided clinical evidence on the feasibility to overcome tumor immune evasion, releasing the brakes enforced by either tumor cells or hijacked myeloid stroma and unleashing a therapeutic anti-tumor immune response (Page et al., 2014). In different human tumors, the PD-1 molecule is mainly present on exhausted T cells idly hanging around at tumor periphery, the interface between the external milieu, tumor cell nests, and inflammatory stroma (Tumeh et al., 2014). On the other hand, the topology and density of memory T cells at the invasive tumor margin is clinically relevant to predict the positive outcome in colorectal cancer (CRC) patients (Galon et al., 2006). Considering these premises, the study of cellular and molecular processes occurring at the invasive tumor margins is crucial to shed light on the conflicting nature of the immune contexture in malignancy. It is clear, in fact, that unidentified environmental cues regulate the balance between antitumor and tumor-promoting activities of T cells (Palucka and Coussens, 2016). The tumor-stroma interface might differ quite substantially between primary tumors and distant tissue metastases. Halama and collaborators previously showed that a peculiar pattern of immune cell clusters, i.e., groups of T cells, monocytes with prognostic and predic-
tive implications, tumor-associated macrophages, and quite scarce NK cells, populate the tumor margin of liver metastases from CRC. The spatial distribution at the interface between the main cellular players in cancer is often controlled by soluble chemoattractants, such as chemokines, as well as reactive species produced within the tumor environment that are able to modify post-translationally and hence alter the chemokine properties (Ugel et al., 2015). The microenvironment of liver CRC metastases is deeply conditioned by a chemokine and chemokine receptor axis involving CCL5 and CCR5, respectively. In this issue of Cancer Cell, Halama and colleagues report the consequences of restraining this loop by inhibiting CCR5 in a fully human ex vivo CRC metastasis explant model, as well as in a pilot clinical study in patients with advanced CRC (Halama et al., 2016). Authors demonstrate that within the CRC invasive margins, T cells, attracted by CXCL9 and CXCL10 released by CD68+ and CD11b+ myeloid elements, stimulate the tumor growth and invasiveness and promote pro-tumoral macrophage polarization by releasing CCL5 (Figure 1). CCL5 (also known as RANTES) is a member of the CC family of chemokines expressed in T cells, platelets, synovial fibroblasts, endothelial cells, and macrophages. CCL5 binds to several receptors, both typical (CCR1, CCR3, CCR5, and CCR4) and atypical (non-signaling receptors like ACKR1, ACKR2, and CCRL2). In cancer, the functions of CCL5 are still unclear, because it contributes to trigger antitumor immune responses but is also associated with cancer progression
and metastasis formation, especially in HER2+ breast cancers (Velasco-Vela´zquez et al., 2014). The study by Halama and collaborators unveils a new mechanism with therapeutic potential. In fact, targeting CCR5 with a negative allosteric inhibitor, maraviroc, to interfere with the binding of CCL5 produced by metastasis-associated T cells induces the polarization of macrophages toward a functional status that resembles, but cannot be properly defined as, M1-like and triggers tumor cell death in patient-derived explant tissues (Figure 1). Myeloid cells unleashed from the inhibitory activity of CCL5 activated STAT3 and reduced the production of VEGF, MIF, and IL-1RA while enhancing the release of IFN-g, IFN-a2, and reactive nitrogen species (RNS); these factors contributed to tumor killing, as well as reshaping macrophage compartment by reducing CD163+ cells (Figure 1). The myeloid phenotypic switch was confirmed in biopsies from patients in response to CCR5 interference therapy (Halama et al., 2016). Unexpectedly, the anti-tumor activity of CCR5 inhibition was not associated with changes in the intra-tumoral number or activation status of metastasis-infiltrating CD8+ T cells. This is in partial contrast with the CRC prognostic value of CD8+ T cells (Galon et al., 2006), which was recently also demonstrated in NSCLC (Schalper et al., 2015). Moreover, the T lymphocytes producing CCL5 in liver metastasis are considered to be exhausted because they express PD-1 and are surrounded by macrophages that express PD-L1. However, while release of IFN-g by T lymphocytes (CD8+ T cell in particular) is one of the main mechanisms Cancer Cell 29, April 11, 2016 437
Cancer Cell
Previews MYELOID NESTS
TUMOR CELLS
VEGF, MIF,CXCL8
CD11b
INTERFACE
CD68
CXCL9 CCR5
+
LYMPHOID NESTS
CD4
CXCL10
PD-1
CCL5
CD163 CD8 PD-1
IFN-γ
CHEMOTHERAPY
IFN-α RNS
CCL5
CCR5 MAROVIROC
Figure 1. Chemokine Network Regulating the Tumor-Stroma Interface and Therapeutic Intervention in Colorectal Cancer
supporting the tumor environmental upregulation of PD-L1 (Page et al., 2014; Palucka and Coussens, 2016), livermetastasis-infiltrating T cells produce CCL5 but no IFN-g (Halama et al., 2016), suggesting an additional, unidentified regulatory circuit. CCL5/CCR3 signaling promotes metastasis formation in luminal breast cancer via Th2 polarization of CD4+ T cells, which have been implicated in fueling chronic inflammation by skewing myeloid cells toward a pro-tumoral and tolerogenic function (Palucka and Coussens, 2016; Velasco-Vela´zquez et al., 2014). It would thus be interesting to know the functional status of CD4+ T cells in liver metastases, before and after CCR5-blocking treatment. Targeting chemokines in combination with chemotherapy may be beneficial, given that cytotoxic agents can increase the immunogenicity by killing tumor cells and by restraining immunosuppressive lymphoid and myeloid populations (Palucka and Coussens, 2016). This might be the case for CCL5/CCR5 interference as well (Figure 1), because objective partial responses were reported in three out of five patients who received a combination of maraviroc and chemotherapy (Ugel et al., 2015; Halama et al., 2016). It should be noted that the selected pa438 Cancer Cell 29, April 11, 2016
tients’ population included heavily pretreated CRC subjects, and the chance of response in this setting is typically less than 10%. Therefore, although observed in only a few patients, the clinical results are encouraging and support a validation with further trials. An obvious question is whether the CCR5 interference might also synergize with PD-1/PD-L1 blockade in CRC patients with liver metastases. According to the available clinical evidence released to date, the immune checkpoint blockade appears to be beneficial for CRC patients having tumors with mismatch-repair defects (i.e., microsatellite instability) (Le et al., 2015). These data are supported by the broader hypothesis that somatic DNA hypermutations, leading to ‘‘non-self’’ neo-epitope generation, direct the immune system to attack neoplastic cells when PD-1/PDL1 signaling is blocked. At present, we do not know whether the CCL5-producing T cells in liver metastases recognize tumor-associated antigens and whether this antigen-specific recognition might influence their functional status and/or polarization. Despite sound preclinical evidence and numerous clinical trials, Mogamulizumab is the only monoclonal antibody targeting a chemokine receptor, CCR4, approved
in Japan for relapsed or refractory CCR4+ adult T cell leukemia, cutaneous T cell lymphoma, and peripheral T cell lymphoma. The road to clinical development of chemokine receptor inhibitors is littered with obstacles, such as the redundancy and pleiotropic activity of chemokines and their receptors, which makes targeting specific molecules often ineffective because single-agent therapy is prone to triggering unpredictable side effects. This is exemplified by the CCL2/CCR2 pathway, one of the main monocyte/ macrophage chemoattractants in several cancers (Ugel et al., 2015). The mAbtargeting CCL2/CCR2 axis carlumab showed only modest activity as a singleagent therapeutic in patients with metastatic, castration-resistant prostate cancer (reviewed in Ugel et al., 2015), making combination therapy with immune modulators an almost obligate step. However, the sudden discontinuation of the CCR2interfering therapy in mice caused severe rebound effects, with mobilization of monocytes from bone marrow and overproduction of IL-6 and VEGF-A that contributed to the metastatic spread of tumor and death of the hosts (Bonapace et al., 2014). Thus, further development of chemokine-based therapy will likely require the identification of non-redundant
Cancer Cell
Previews pathogenic circuits, definition of biomarkers, and ad hoc immune monitoring to follow the dynamic of lymphoid and myeloid cell subsets, as well as circulating cancer cells, during the treatment. In this regard, the original work by Halama and colleagues introduces the concept to target directly a distinctive pathway that CRC exploits, together with immune cells, to metastasize successfully to the liver.
E.B. is supported by the Italian Association for Cancer Research (AIRC-MFAG no. 14282).
Page, D.B., Postow, M.A., Callahan, M.K., Allison, J.P., and Wolchok, J.D. (2014). Annu. Rev. Med. 65, 185–202.
REFERENCES
Palucka, A.K., and Coussens, L.M. (2016). Cell 164, 1233–1247.
ACKNOWLEDGMENTS
Halama, N., Zoernig, I., Berthel, A., Kahlert, C., Klupp, F., Suarez-Carmona, M., Suetterlin, T., Brand, K., Krauss, J., Lasitschka, F., et al. (2016). Cancer Cell 29, this issue, 587–601.
V.B is supported by grants from the Italian Ministry of Health (FINALIZZATA 2011-2012 RF-201102348435 cup: E35G1400019001), the Italian Association for Cancer Research (AIRC, 6599, 12182, 14103), and the Fondazione Cassa di Risparmio di Verona, Vicenza, Belluno e Ancona.
Bonapace, L., Coissieux, M.M., Wyckoff, J., Mertz, K.D., Varga, Z., Junt, T., and Bentires-Alj, M. (2014). Nature 515, 130–133. Galon, J., Costes, A., Sanchez-Cabo, F., Kirilovsky, A., Mlecnik, B., Lagorce-Page`s, C., Tosolini, M., Camus, M., Berger, A., Wind, P., et al. (2006). Science 313, 1960–1964.
Le, D.T., Uram, J.N., Wang, H., Bartlett, B.R., Kemberling, H., Eyring, A.D., Skora, A.D., Luber, B.S., Azad, N.S., Laheru, D., et al. (2015). N. Engl. J. Med. 372, 2509–2520.
Schalper, K.A., Brown, J., Carvajal-Hausdorf, D., McLaughlin, J., Velcheti, V., Syrigos, K.N., Herbst, R.S., and Rimm, D.L. (2015). J. Natl. Cancer Inst. 107, dju435. Tumeh, P.C., Harview, C.L., Yearley, J.H., Shintaku, I.P., Taylor, E.J., Robert, L., Chmielowski, B., Spasic, M., Henry, G., Ciobanu, V., et al. (2014). Nature 515, 568–571. Ugel, S., De Sanctis, F., Mandruzzato, S., and Bronte, V. (2015). J. Clin. Invest. 125, 3365–3376. Velasco-Vela´zquez, M., Xolalpa, W., and Pestell, R.G. (2014). Expert Opin. Ther. Targets 18, 1265– 1275.
Cancer Cell 29, April 11, 2016 439
Previews Interfering with CCL5/CCR5 at the Tumor-Stroma Interface Vincenzo Bronte1,* and Emilio Bria2 1Immunology,
Department of Medicine, Verona University Hospital, Verona 37134, Italy Oncology, Department of Medicine, Verona University Hospital, Verona 37134, Italy *Correspondence: [email protected] http://dx.doi.org/10.1016/j.ccell.2016.03.019 2Medical
In this issue of Cancer Cell, Halama et al. (2016) further advance chemokine interference as a therapeutic option for cancer by demonstrating the effect of CCR5 blockade in reshaping macrophage polarization toward an anti-tumor functional state in patient-derived tumor models and liver metastases of colorectal cancer patients. During the last two years, the introduction of immune checkpoint inhibitors has reshaped the current standard of care for melanoma and non-small-cell lung cancer (NSCLC) patients. The development of monoclonal antibodies (mAbs) that interfere with the crosstalk between immune and cancer cells, particularly with the PD-1/PD-L1 blockade, has provided clinical evidence on the feasibility to overcome tumor immune evasion, releasing the brakes enforced by either tumor cells or hijacked myeloid stroma and unleashing a therapeutic anti-tumor immune response (Page et al., 2014). In different human tumors, the PD-1 molecule is mainly present on exhausted T cells idly hanging around at tumor periphery, the interface between the external milieu, tumor cell nests, and inflammatory stroma (Tumeh et al., 2014). On the other hand, the topology and density of memory T cells at the invasive tumor margin is clinically relevant to predict the positive outcome in colorectal cancer (CRC) patients (Galon et al., 2006). Considering these premises, the study of cellular and molecular processes occurring at the invasive tumor margins is crucial to shed light on the conflicting nature of the immune contexture in malignancy. It is clear, in fact, that unidentified environmental cues regulate the balance between antitumor and tumor-promoting activities of T cells (Palucka and Coussens, 2016). The tumor-stroma interface might differ quite substantially between primary tumors and distant tissue metastases. Halama and collaborators previously showed that a peculiar pattern of immune cell clusters, i.e., groups of T cells, monocytes with prognostic and predic-
tive implications, tumor-associated macrophages, and quite scarce NK cells, populate the tumor margin of liver metastases from CRC. The spatial distribution at the interface between the main cellular players in cancer is often controlled by soluble chemoattractants, such as chemokines, as well as reactive species produced within the tumor environment that are able to modify post-translationally and hence alter the chemokine properties (Ugel et al., 2015). The microenvironment of liver CRC metastases is deeply conditioned by a chemokine and chemokine receptor axis involving CCL5 and CCR5, respectively. In this issue of Cancer Cell, Halama and colleagues report the consequences of restraining this loop by inhibiting CCR5 in a fully human ex vivo CRC metastasis explant model, as well as in a pilot clinical study in patients with advanced CRC (Halama et al., 2016). Authors demonstrate that within the CRC invasive margins, T cells, attracted by CXCL9 and CXCL10 released by CD68+ and CD11b+ myeloid elements, stimulate the tumor growth and invasiveness and promote pro-tumoral macrophage polarization by releasing CCL5 (Figure 1). CCL5 (also known as RANTES) is a member of the CC family of chemokines expressed in T cells, platelets, synovial fibroblasts, endothelial cells, and macrophages. CCL5 binds to several receptors, both typical (CCR1, CCR3, CCR5, and CCR4) and atypical (non-signaling receptors like ACKR1, ACKR2, and CCRL2). In cancer, the functions of CCL5 are still unclear, because it contributes to trigger antitumor immune responses but is also associated with cancer progression
and metastasis formation, especially in HER2+ breast cancers (Velasco-Vela´zquez et al., 2014). The study by Halama and collaborators unveils a new mechanism with therapeutic potential. In fact, targeting CCR5 with a negative allosteric inhibitor, maraviroc, to interfere with the binding of CCL5 produced by metastasis-associated T cells induces the polarization of macrophages toward a functional status that resembles, but cannot be properly defined as, M1-like and triggers tumor cell death in patient-derived explant tissues (Figure 1). Myeloid cells unleashed from the inhibitory activity of CCL5 activated STAT3 and reduced the production of VEGF, MIF, and IL-1RA while enhancing the release of IFN-g, IFN-a2, and reactive nitrogen species (RNS); these factors contributed to tumor killing, as well as reshaping macrophage compartment by reducing CD163+ cells (Figure 1). The myeloid phenotypic switch was confirmed in biopsies from patients in response to CCR5 interference therapy (Halama et al., 2016). Unexpectedly, the anti-tumor activity of CCR5 inhibition was not associated with changes in the intra-tumoral number or activation status of metastasis-infiltrating CD8+ T cells. This is in partial contrast with the CRC prognostic value of CD8+ T cells (Galon et al., 2006), which was recently also demonstrated in NSCLC (Schalper et al., 2015). Moreover, the T lymphocytes producing CCL5 in liver metastasis are considered to be exhausted because they express PD-1 and are surrounded by macrophages that express PD-L1. However, while release of IFN-g by T lymphocytes (CD8+ T cell in particular) is one of the main mechanisms Cancer Cell 29, April 11, 2016 437
Cancer Cell
Previews MYELOID NESTS
TUMOR CELLS
VEGF, MIF,CXCL8
CD11b
INTERFACE
CD68
CXCL9 CCR5
+
LYMPHOID NESTS
CD4
CXCL10
PD-1
CCL5
CD163 CD8 PD-1
IFN-γ
CHEMOTHERAPY
IFN-α RNS
CCL5
CCR5 MAROVIROC
Figure 1. Chemokine Network Regulating the Tumor-Stroma Interface and Therapeutic Intervention in Colorectal Cancer
supporting the tumor environmental upregulation of PD-L1 (Page et al., 2014; Palucka and Coussens, 2016), livermetastasis-infiltrating T cells produce CCL5 but no IFN-g (Halama et al., 2016), suggesting an additional, unidentified regulatory circuit. CCL5/CCR3 signaling promotes metastasis formation in luminal breast cancer via Th2 polarization of CD4+ T cells, which have been implicated in fueling chronic inflammation by skewing myeloid cells toward a pro-tumoral and tolerogenic function (Palucka and Coussens, 2016; Velasco-Vela´zquez et al., 2014). It would thus be interesting to know the functional status of CD4+ T cells in liver metastases, before and after CCR5-blocking treatment. Targeting chemokines in combination with chemotherapy may be beneficial, given that cytotoxic agents can increase the immunogenicity by killing tumor cells and by restraining immunosuppressive lymphoid and myeloid populations (Palucka and Coussens, 2016). This might be the case for CCL5/CCR5 interference as well (Figure 1), because objective partial responses were reported in three out of five patients who received a combination of maraviroc and chemotherapy (Ugel et al., 2015; Halama et al., 2016). It should be noted that the selected pa438 Cancer Cell 29, April 11, 2016
tients’ population included heavily pretreated CRC subjects, and the chance of response in this setting is typically less than 10%. Therefore, although observed in only a few patients, the clinical results are encouraging and support a validation with further trials. An obvious question is whether the CCR5 interference might also synergize with PD-1/PD-L1 blockade in CRC patients with liver metastases. According to the available clinical evidence released to date, the immune checkpoint blockade appears to be beneficial for CRC patients having tumors with mismatch-repair defects (i.e., microsatellite instability) (Le et al., 2015). These data are supported by the broader hypothesis that somatic DNA hypermutations, leading to ‘‘non-self’’ neo-epitope generation, direct the immune system to attack neoplastic cells when PD-1/PDL1 signaling is blocked. At present, we do not know whether the CCL5-producing T cells in liver metastases recognize tumor-associated antigens and whether this antigen-specific recognition might influence their functional status and/or polarization. Despite sound preclinical evidence and numerous clinical trials, Mogamulizumab is the only monoclonal antibody targeting a chemokine receptor, CCR4, approved
in Japan for relapsed or refractory CCR4+ adult T cell leukemia, cutaneous T cell lymphoma, and peripheral T cell lymphoma. The road to clinical development of chemokine receptor inhibitors is littered with obstacles, such as the redundancy and pleiotropic activity of chemokines and their receptors, which makes targeting specific molecules often ineffective because single-agent therapy is prone to triggering unpredictable side effects. This is exemplified by the CCL2/CCR2 pathway, one of the main monocyte/ macrophage chemoattractants in several cancers (Ugel et al., 2015). The mAbtargeting CCL2/CCR2 axis carlumab showed only modest activity as a singleagent therapeutic in patients with metastatic, castration-resistant prostate cancer (reviewed in Ugel et al., 2015), making combination therapy with immune modulators an almost obligate step. However, the sudden discontinuation of the CCR2interfering therapy in mice caused severe rebound effects, with mobilization of monocytes from bone marrow and overproduction of IL-6 and VEGF-A that contributed to the metastatic spread of tumor and death of the hosts (Bonapace et al., 2014). Thus, further development of chemokine-based therapy will likely require the identification of non-redundant
Cancer Cell
Previews pathogenic circuits, definition of biomarkers, and ad hoc immune monitoring to follow the dynamic of lymphoid and myeloid cell subsets, as well as circulating cancer cells, during the treatment. In this regard, the original work by Halama and colleagues introduces the concept to target directly a distinctive pathway that CRC exploits, together with immune cells, to metastasize successfully to the liver.
E.B. is supported by the Italian Association for Cancer Research (AIRC-MFAG no. 14282).
Page, D.B., Postow, M.A., Callahan, M.K., Allison, J.P., and Wolchok, J.D. (2014). Annu. Rev. Med. 65, 185–202.
REFERENCES
Palucka, A.K., and Coussens, L.M. (2016). Cell 164, 1233–1247.
ACKNOWLEDGMENTS
Halama, N., Zoernig, I., Berthel, A., Kahlert, C., Klupp, F., Suarez-Carmona, M., Suetterlin, T., Brand, K., Krauss, J., Lasitschka, F., et al. (2016). Cancer Cell 29, this issue, 587–601.
V.B is supported by grants from the Italian Ministry of Health (FINALIZZATA 2011-2012 RF-201102348435 cup: E35G1400019001), the Italian Association for Cancer Research (AIRC, 6599, 12182, 14103), and the Fondazione Cassa di Risparmio di Verona, Vicenza, Belluno e Ancona.
Bonapace, L., Coissieux, M.M., Wyckoff, J., Mertz, K.D., Varga, Z., Junt, T., and Bentires-Alj, M. (2014). Nature 515, 130–133. Galon, J., Costes, A., Sanchez-Cabo, F., Kirilovsky, A., Mlecnik, B., Lagorce-Page`s, C., Tosolini, M., Camus, M., Berger, A., Wind, P., et al. (2006). Science 313, 1960–1964.
Le, D.T., Uram, J.N., Wang, H., Bartlett, B.R., Kemberling, H., Eyring, A.D., Skora, A.D., Luber, B.S., Azad, N.S., Laheru, D., et al. (2015). N. Engl. J. Med. 372, 2509–2520.
Schalper, K.A., Brown, J., Carvajal-Hausdorf, D., McLaughlin, J., Velcheti, V., Syrigos, K.N., Herbst, R.S., and Rimm, D.L. (2015). J. Natl. Cancer Inst. 107, dju435. Tumeh, P.C., Harview, C.L., Yearley, J.H., Shintaku, I.P., Taylor, E.J., Robert, L., Chmielowski, B., Spasic, M., Henry, G., Ciobanu, V., et al. (2014). Nature 515, 568–571. Ugel, S., De Sanctis, F., Mandruzzato, S., and Bronte, V. (2015). J. Clin. Invest. 125, 3365–3376. Velasco-Vela´zquez, M., Xolalpa, W., and Pestell, R.G. (2014). Expert Opin. Ther. Targets 18, 1265– 1275.
Cancer Cell 29, April 11, 2016 439