Periodic Reporting for period 2 - ONCOTHERANOSTICS (Advanced Theranostic Nanomedicines for Oncology. Development of new combinatorial therapies for primary and metastatic Breast Cancer.)
Reporting period: 2021-03-01 to 2022-02-28
Despite dedicating enormous research and socioeconomic efforts, cancer remains as the second cause of death globally. Furthermore, the economic impact of cancer is significant and it is increasing. Among different tumor types, breast cancer has the highest incidence among women, causing 684996 deaths worldwide in 2020, and being the fourth cause of cancer related deaths. Brain cancer has a very poor prognosis and the treatment options very limited. Thus, any improvement in cancer treatment will have a great impact in the health of millions of patients and will benefit the society as a whole.
In recent years, cancer immunotherapies have gained significant importance. These therapies are designed to activate the immune system against cancer cells. The field has been recently revitalized with the discovery of immune checkpoints such as programmed cell death protein-1 (PD-1) and its ligand (PD-L1). As the regulators of the immune system activation, these immune checkpoints are utilized by cancer cells to escape immune surveillance. Immunotherapies aim to trigger an immune response against cancer cells by blocking immune checkpoints used by cancer cells to escape immune destruction. PD-L1 is often overexpressed in cancer and it has been successfully exploited for immune therapy in different tumor types, such as melanoma, non-small cell lung carcinoma and renal cell carcinoma. However, treatment outcomes have not been as effective in other cancers such as breast cancer or gliomas. The explanation for this lack of efficacy is multifactorial, but several studies point towards cancer aberrant metabolism as one of the key causes. Although most cancers exhibit an aberrant metabolism, one common feature shared by most of them is the increased levels of phosphocholine (PC) and total choline-containing compounds. These changes have been attributed to the overexpression and increased activity of choline kinase (Chk)-α in malignant cells.
The main objective of ONCOTHERANOSTICS is to assess the mechanism of immunotherapies failure and to develop novel approaches that allow to overcome tumor resistance. This overall objective is divided in multiple specific objectives, one of them being completed during this period and the second still under study. The first specific objective is to investigate the molecular links between tumor metabolism, cancer acquired immune resistance and immunotherapies failure in vivo in a breast cancer model. The second specific objective is to assess the link between PD-L1 and tumor metabolomics in gliomas.
In recent years, cancer immunotherapies have gained significant importance. These therapies are designed to activate the immune system against cancer cells. The field has been recently revitalized with the discovery of immune checkpoints such as programmed cell death protein-1 (PD-1) and its ligand (PD-L1). As the regulators of the immune system activation, these immune checkpoints are utilized by cancer cells to escape immune surveillance. Immunotherapies aim to trigger an immune response against cancer cells by blocking immune checkpoints used by cancer cells to escape immune destruction. PD-L1 is often overexpressed in cancer and it has been successfully exploited for immune therapy in different tumor types, such as melanoma, non-small cell lung carcinoma and renal cell carcinoma. However, treatment outcomes have not been as effective in other cancers such as breast cancer or gliomas. The explanation for this lack of efficacy is multifactorial, but several studies point towards cancer aberrant metabolism as one of the key causes. Although most cancers exhibit an aberrant metabolism, one common feature shared by most of them is the increased levels of phosphocholine (PC) and total choline-containing compounds. These changes have been attributed to the overexpression and increased activity of choline kinase (Chk)-α in malignant cells.
The main objective of ONCOTHERANOSTICS is to assess the mechanism of immunotherapies failure and to develop novel approaches that allow to overcome tumor resistance. This overall objective is divided in multiple specific objectives, one of them being completed during this period and the second still under study. The first specific objective is to investigate the molecular links between tumor metabolism, cancer acquired immune resistance and immunotherapies failure in vivo in a breast cancer model. The second specific objective is to assess the link between PD-L1 and tumor metabolomics in gliomas.
The work described in this report has been performed in The Instituto de Investigaciones Biomédicas "Alberto Sols" (IIBM), under the supervision of Professors Bhujwalla and Cerdan.
Specific Objective 1 (SO1): Study of the relationship between cancer aberrant metabolism and the expression of the immune checkpoint inhibitor PD-L1 in vivo in a breast cancer model.
Work performed: these studies were carried out in vivo using a murine breast cancer model 4T1. Multiple imaging methodologies were used, combining MRI, MRS, PET and bioluminescence.
Main Results: data showed that tumor regions with low PD-L1 expression depicted high levels of choline containing compounds and high levels of lipids, in good agreement with our previous results. I also found a previous unknow relationship as high PD-L1 levels were spatially corelated with hypoxic areas of the tumor.
SO3: Assessing the interplay between tumor metabolism and PD-L1 in brain tumors.
Work performed: these studies were carried in vitro using genetically modified glioma cell lines that were treated with small interfering RNA (siRNA) in order to decrease the expression of PD-L1, and small molecules to modulate its metabolism. The effects of the treatments were studied at the genomic, proteomic, metabolomic levels.
Main Results: we identified that PD-L1 has an impact in tumor metabolomic, as decreasing the levels of PD-L1 increased the levels of relevant enzymes responsible of altered tumor metabolism in gliomas (Figure 1). Interestingly, we also found that the levels of PD-L1 are greatly affected the tumor metabolism. Treating the cells with metabolic inhibitors increased the level of PD-L1 depending on the genetic background on the glioma.
Specific Objective 1 (SO1): Study of the relationship between cancer aberrant metabolism and the expression of the immune checkpoint inhibitor PD-L1 in vivo in a breast cancer model.
Work performed: these studies were carried out in vivo using a murine breast cancer model 4T1. Multiple imaging methodologies were used, combining MRI, MRS, PET and bioluminescence.
Main Results: data showed that tumor regions with low PD-L1 expression depicted high levels of choline containing compounds and high levels of lipids, in good agreement with our previous results. I also found a previous unknow relationship as high PD-L1 levels were spatially corelated with hypoxic areas of the tumor.
SO3: Assessing the interplay between tumor metabolism and PD-L1 in brain tumors.
Work performed: these studies were carried in vitro using genetically modified glioma cell lines that were treated with small interfering RNA (siRNA) in order to decrease the expression of PD-L1, and small molecules to modulate its metabolism. The effects of the treatments were studied at the genomic, proteomic, metabolomic levels.
Main Results: we identified that PD-L1 has an impact in tumor metabolomic, as decreasing the levels of PD-L1 increased the levels of relevant enzymes responsible of altered tumor metabolism in gliomas (Figure 1). Interestingly, we also found that the levels of PD-L1 are greatly affected the tumor metabolism. Treating the cells with metabolic inhibitors increased the level of PD-L1 depending on the genetic background on the glioma.
SO1: Study of the relationship between cancer aberrant metabolism and the expression of the immune checkpoint inhibitor PD-L1.
Progress beyond the state of the art: our data demonstrated that there is an inverse correlation between PD-L1 and choline containing compounds and lipids in vivo. This link may contribute to cancer cells escaping immune surveillance. Furthermore, the data also showed that PD-L1 expression in vivo is related to tumoral hypoxia.
Future Results: a major unmet need in treatment with immune checkpoint inhibitors is the lack of a noninvasive technique to identify patients who may benefit from such a therapy. Our results suggest that tumors with low PD-L1 expression may have total choline and lipids that can be detected noninvasively with MRS. Future studies relating total choline detected by 1H MRS in tumors to PD-L1 expression in biopsy samples will provide further evidence for the development of new biomarkers to predict for PD-L1 expression levels.
Potential impacts: these results have a great impact in the understanding of how different tumors acquired immune resistance and why immunotherapies fail in some patients. The impact of PD-L1 in tumor metabolomics paves a new avenue to understand the failure of therapies based on antibodies targeting PD-L1.
SO2: Assessing the interplay between tumor metabolism and PD-L1 in brain tumors.
Progress beyond the state of the art: the data demonstrated that the relationship between tumor metabolism and PD-L1 expression found in breast cancer is also present in other tumor types. These results showed that treating cancer cells with specific metabolic inhibitors have an impact in PD-L1 levels, shifting cells towards a more immunosuppressive profile. It is important to stress that the impact of metabolome on PD-L1 levels seem to be dependent on the genetic background of the tumor.
Future Results: future studies will evaluate the impact of modulating tumor metabolome in glioblastomas in vivo with the expression of PD-L1, as well to correlate these changes with the natural immune response and the tumor microenvironment.
Potential impacts: the increase of PD-L1 as a consequence of metabolic reprograming indicated that metabolic directed treatments may result in cancer cells escaping immune surveillance, opening an explanation of the failure of these approaches. On the other hand, the impact of PD-L1 downregulation on tumor metabolomics in glioblastoma may explain the failure of therapies based on antibodies targeting PD-L1. These observations provide new insights that can be applied to the rational design of combinatorial therapies targeting immune checkpoints and cancer metabolism.
Progress beyond the state of the art: our data demonstrated that there is an inverse correlation between PD-L1 and choline containing compounds and lipids in vivo. This link may contribute to cancer cells escaping immune surveillance. Furthermore, the data also showed that PD-L1 expression in vivo is related to tumoral hypoxia.
Future Results: a major unmet need in treatment with immune checkpoint inhibitors is the lack of a noninvasive technique to identify patients who may benefit from such a therapy. Our results suggest that tumors with low PD-L1 expression may have total choline and lipids that can be detected noninvasively with MRS. Future studies relating total choline detected by 1H MRS in tumors to PD-L1 expression in biopsy samples will provide further evidence for the development of new biomarkers to predict for PD-L1 expression levels.
Potential impacts: these results have a great impact in the understanding of how different tumors acquired immune resistance and why immunotherapies fail in some patients. The impact of PD-L1 in tumor metabolomics paves a new avenue to understand the failure of therapies based on antibodies targeting PD-L1.
SO2: Assessing the interplay between tumor metabolism and PD-L1 in brain tumors.
Progress beyond the state of the art: the data demonstrated that the relationship between tumor metabolism and PD-L1 expression found in breast cancer is also present in other tumor types. These results showed that treating cancer cells with specific metabolic inhibitors have an impact in PD-L1 levels, shifting cells towards a more immunosuppressive profile. It is important to stress that the impact of metabolome on PD-L1 levels seem to be dependent on the genetic background of the tumor.
Future Results: future studies will evaluate the impact of modulating tumor metabolome in glioblastomas in vivo with the expression of PD-L1, as well to correlate these changes with the natural immune response and the tumor microenvironment.
Potential impacts: the increase of PD-L1 as a consequence of metabolic reprograming indicated that metabolic directed treatments may result in cancer cells escaping immune surveillance, opening an explanation of the failure of these approaches. On the other hand, the impact of PD-L1 downregulation on tumor metabolomics in glioblastoma may explain the failure of therapies based on antibodies targeting PD-L1. These observations provide new insights that can be applied to the rational design of combinatorial therapies targeting immune checkpoints and cancer metabolism.