Oncogene addiction as a foundational rationale for targeted anti-cancer therapy: promises and perils

A decade has elapsed since the concept of oncogene addiction was first proposed. It postulates that – despite the diverse array of genetic lesions typical of cancer – some tumours rely on one single dominant oncogene for growth and survival, so that inhibition of this specific oncogene is sufficient to halt the neoplastic phenotype. A large amount of evidence has proven the pervasive power of this notion, both in basic research and in therapeutic applications. However, in the face of such a considerable body of knowledge, the intimate molecular mechanisms mediating this phenomenon remain elusive. At the clinical level, successful translation of the oncogene addiction model into the rational and effective design of targeted therapeutics against individual oncoproteins still faces major obstacles, mainly due to the emergence of escape mechanisms and drug resistance. Here, we offer an overview of the relevant literature, encompassing both biological aspects and recent clinical insights. We discuss the key advantages and pitfalls of this concept and reconsider it as an illustrative principle to guide post-genomic cancer research and drug development

The Stromal and Immune Landscape of Colorectal Cancer Progression during Anti-EGFR Therapy

The EGFR antibodies cetuximab and panitumumab are used in patients with EGFR-expressing, KRAS, or NRAS wild-type metastatic colorectal cancer (mCRC) either in combination with standard chemotherapy, for first-line treatment, or as single agents when tumors become resistant to prior cytotoxic regimens. However, only 20% of individuals experience tumor regressions, and only an additional 30% have some extent of clinical benefit in terms of disease stabilization (Douillard et al., 2013). This relatively low response rate is compounded by the dismal reality that subjects who initially respond typically become refractory to treatment in a period of months. In this issue of Cancer Cell, Woolston et al., 2019 offer a comprehensive picture of the identifying traits of primary and acquired resistance to cetuximab in a cohort of 35 mCRC patients (Figure 1). In a difference from previous studies, mostly conducted in a retrospective manner and focused on a small number of candidate biomarkers, here the authors embarked on a prospective trial whereby biopsies collected before initiation of single-agent cetuximab and at the time of disease progression were subjected to whole-exome and RNA-sequencing analyses and immunophenotyping

Rational treatment of metastatic colorectal cancer: A reverse tale of men, mice, and culture dishes

Stratification of colorectal cancer into subgroups with different response to therapy was initially guided by descriptive associations between specific biomarkers and treatment outcome. Recently, preclinical models based on propagatable patient-derived tumor samples have yielded an improved understanding of disease biology, which has facilitated the functional validation of correlative information and the discovery of novel response determinants, therapeutic targets, and mechanisms of tumor adaptation and drug resistance. We review the contribution of patient-derived models to advancing colorectal cancer characterization, discuss their influence on clinical decision-making, and highlight emerging challenges in the interpretation and clinical transferability of results obtainable with such approaches. SIGNIFICANCE: Association studies in patients with colorectal cancer have led to the identification of response biomarkers, some of which have been implemented as companion diagnostics for therapeutic decisions. By enabling biological investigation in a clinically relevant experimental context, patient-derived colorectal cancer models have proved useful to examine the causal role of such biomarkers in dictating drug sensitivity and are providing fresh knowledge on new actionable targets, dynamics of tumor evolution and adaptation, and mechanisms of drug resistance

Inhibition of poly(ADP-ribosyl)ation in cancer: Old and new paradigms revisited

Abstract Inhibitors of poly(ADP-ribose) polymerases actualized the biological concept of synthetic lethality in the clinical practice, yielding a paradigmatic example of translational medicine. The profound sensitivity of tumors with germline BRCA mutations to PARP1/2 blockade owes to inherent defects of the BRCA-dependent homologous recombination machinery, which are unleashed by interruption of PARP DNA repair activity and lead to DNA damage overload and cell death. Conversely, aspirant BRCA-like tumors harboring somatic DNA repair dysfunctions (a vast entity of genetic and epigenetic defects known as "BRCAness") not always align with the familial counterpart and appear not to be equally sensitive to PARP inhibition. The acquisition of secondary resistance in initially responsive patients and the lack of standardized biomarkers to identify "BRCAness" pose serious threats to the clinical advance of PARP inhibitors; a feeling is also emerging that a BRCA-centered perspective might have missed the influence of additional, not negligible and DNA repair-independent PARP contributions onto therapy outcome. While regulatory approval for PARP1/2 inhibitors is still pending, novel therapeutic opportunities are sprouting from different branches of the PARP family, although they remain immature for clinical extrapolation. This review is an endeavor to provide a comprehensive appraisal of the multifaceted biology of PARPs and their evolving impact on cancer therapeutics

Immunogenomics of Colorectal Tumors: Facts and Hypotheses on an Evolving Saga

Different mutational burden only partially explains the different response of MSI and MSS CRCs to immunotherapy. Neoantigen load, as measured using available prediction algorithms, is not sufficiently accurate for implementation into clinical decision making. Abundant immune infiltration in the tumor tissue is likely to have high prognostic value, but not an equally high predictive value in terms of response to immunotherapy. The intrinsic characteristics of MSI and MSS CRCs determine differences in their evolutionary paths, which inevitably influence the way the immune system sculpts tumor clonal and subclonal dynamics. Immunotherapy with immune checkpoint inhibitors is an approved treatment option for a subpopulation of patients with colorectal cancers that display microsatellite instability. However, not all individuals within this subgroup respond to immunotherapy, and molecular biomarkers for effective patient stratification are still lacking. In this opinion article, we provide an overview of the different biological parameters that contribute to rendering colorectal cancers with microsatellite instability potentially sensitive to immunotherapy. We critically discuss the reasons why such parameters have limited predictive value and the implications therein. We also consider that a more informed knowledge of response determinants in this tumor subtype could help understand the mechanisms of immunotherapy resistance in microsatellite stable tumors. We conclude that the dynamic nature of the interactions between cancer and immune cells complicates conventional biomarker development and argue that a new generation of adaptive metrics, borrowed from evolutionary genetics, may improve the effectiveness and reliability of clinical decision making

Beta 1-integrin-c-Met cooperation reveals an inside-in survival signalling on autophagy-related endomembranes

This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/R.B.M. was a recipient of a UK Medical Research Council (MRC) studentship, MRC Centenary Award, Barts and The London Charity (472/1711) and Rosetrees Trust (M314), N.K. was a recipient of an MRC studentship (MR/J500409/1), C.J. was a recipient of the Barts and The London Charitable Foundation Scholarship (RAB 05/PJ/07), L.M. was supported by CR-UK, Breast Cancer Now (2008NovPR10) and Rosetrees Trust (M346), A.H. was a recipient of a CR-UK studentship (C236/A11795). P.J.P. was supported by CR-UK. J.I. was supported by grants from the Academy of Finland, ERC Starting grant, Finnish Cancer Organisations and Sigrid Juselius Foundation. S.K. was supported by the MRC (G0501003) and The British Lung Foundation (CAN09-4)

Lenalidomide normalizes tumor vessels in colorectal cancer improving chemotherapy activity

BACKGROUND: Angiogenesis inhibition is a promising approach for treating metastatic colorectal cancer (mCRC). Recent evidences support the seemingly counterintuitive ability of certain antiangiogenic drugs to promote normalization of residual tumor vessels with important clinical implications. Lenalidomide is an oral drug with immune-modulatory and anti-angiogenic activity against selected hematologic malignancies but as yet little is known regarding its effectiveness for solid tumors. The aim of this study was to determine whether lenalidomide can normalize colorectal cancer neo-vessels in vivo, thus reducing tumor hypoxia and improving the benefit of chemotherapy. METHODS: We set up a tumorgraft model with NOD/SCID mice implanted with a patient-derived colorectal cancer liver metastasis. The mice were treated with oral lenalidomide (50 mg/Kg/day for 28 days), intraperitoneal 5-fluorouracil (5FU) (20 mg/Kg twice weekly for 3 weeks), combination (combo) of lenalidomide and 5FU or irrelevant vehicle. We assessed tumor vessel density (CD146), pericyte coverage (NG2; alphaSMA), in vivo perfusion capability of residual vessels (lectin distribution essay), hypoxic areas (HP2-100 Hypoxyprobe) and antitumor activity in vivo and in vitro. RESULTS: Treatment with lenalidomide reduced tumor vessel density (p = 0.0001) and enhanced mature pericyte coverage of residual vessels (p = 0.002). Perfusion capability of tumor vessels was enhanced in mice treated with lenalidomide compared to controls (p = 0.004). Accordingly, lenalidomide reduced hypoxic tumor areas (p = 0.002) and enhanced the antitumor activity of 5FU in vivo. The combo treatment delayed tumor growth (p = 0.01) and significantly reduced the Ki67 index (p = 0.0002). Lenalidomide alone did not demonstrate antitumor activity compared to untreated controls in vivo or against 4 different mCRC cell lines in vitro. CONCLUSIONS: We provide the first evidence of tumor vessel normalization and hypoxia reduction induced by lenalidomide in mCRC in vivo. This effect, seemingly counterintuitive for an antiangiogenic compound, translates into indirect antitumor activity thus enhancing the therapeutic index of chemotherapy. Our findings suggest that further research should be carried out on synergism between lenalidomide and conventional therapies for treating solid tumors that might benefit from tumor vasculature normalization