Cell death pathologies: targeting death pathways and the immune system for cancer therapy

Alterations in the molecular mechanisms of cell death are a common feature of cancer. These alterations enable malignant cells to survive intrinsic death signalling leading to accumulation of genetic aberrations and helping them to cope with adverse conditions. Regulated cell death has historically been exclusively associated with classical apoptosis; however, increasing evidence indicates that several alternative mechanisms orchestrate multiple death pathways, such as ferroptosis, entosis, necroptosis and immunogenic cell death, each with distinct underlying molecular mechanisms. Although pharmacological targeting of cell death pathways has been the subject of intensive efforts in recent decades with a dominant focus on targeting apoptosis, the identification of these novel death pathways has opened additional venues for intervention in cancer cells and the immune system. In this mini-review, we cover some recent progress on major recently emerged cell death modalities, emphasizing their potential clinical and therapeutic implications. We also discuss the interplay between cell death and immune response, highlighting the potential of the combination of traditional anticancer therapy and immunocheckpoint blockade. While attempting to stimulate discussion and draw attention to the possible clinical impact of these more recently emerged cell death modalities, we also cover the major progress achieved in translating strategies for manipulation of apoptotic pathways into the clinic, focusing on the attempts to target the anti-apoptotic protein BCL2 and the tumour suppressor p53.

[1]  Jian-hua Xu,et al.  Autophagy-related IRGM genes confer susceptibility to ankylosing spondylitis in a Chinese female population: a case–control study , 2016, Genes and Immunity.

[2]  James M. Wilson,et al.  Gendicine: the first commercial gene therapy product. , 2005, Human gene therapy.

[3]  M. Overholtzer,et al.  Mechanisms of ploidy increase in human cancers: a new role for cell cannibalism. , 2012, Cancer research.

[4]  A. Stegh Targeting the p53 signaling pathway in cancer therapy – the promises, challenges and perils , 2012, Expert opinion on therapeutic targets.

[5]  I. Amelio,et al.  TAp73 contributes to the oxidative stress response by regulating protein synthesis , 2018, Proceedings of the National Academy of Sciences.

[6]  P. Sutton,et al.  The MUC1 mucin specifically inhibits activation of the NLRP3 inflammasome , 2016, Genes and Immunity.

[7]  Qiang Sun,et al.  Induction of entosis by epithelial cadherin expression , 2014, Cell Research.

[8]  M. Overholtzer,et al.  Mechanisms and consequences of entosis , 2016, Cellular and Molecular Life Sciences.

[9]  R. Schwabe,et al.  Damage-associated molecular patterns in cancer: A double-edged sword , 2016, Oncogene.

[10]  S. Lipton,et al.  Molecular mechanisms of cell death: recommendations of the Nomenclature Committee on Cell Death 2018 , 2018, Cell Death & Differentiation.

[11]  J. Marine,et al.  Apoptosis of Sertoli cells after conditional ablation of murine double minute 2 (Mdm2) gene is p53-dependent and results in male sterility , 2015, Cell Death and Differentiation.

[12]  D. Mestivier,et al.  Alterations of the immunosuppressive IL4I1 enzyme activity induced by naturally occurring SNP/mutations , 2015, Genes and Immunity.

[13]  Randall W. King,et al.  A Nonapoptotic Cell Death Process, Entosis, that Occurs by Cell-in-Cell Invasion , 2007, Cell.

[14]  E. Morselli,et al.  Targeting post-mitochondrial effectors of apoptosis for neuroprotection. , 2009, Biochimica et biophysica acta.

[15]  W. Hong,et al.  Retrovirus–mediated wild–type P53 gene transfer to tumors of patients with lung cancer. , 1996, Nature Medicine.

[16]  A. Letai,et al.  Blastic Plasmacytoid Dendritic Cell Neoplasm Is Dependent on BCL2 and Sensitive to Venetoclax. , 2017, Cancer discovery.

[17]  L. Lam,et al.  Souers AJ, Leverson JD, Boghaert ER et al.ABT-199, a potent and selective BCL-2 inhibitor, achieves antitumor activity while sparing platelets. Nat Med 19:202-208 , 2013 .

[18]  Flore Kruiswijk,et al.  p53 in survival, death and metabolic health: a lifeguard with a licence to kill , 2015, Nature Reviews Molecular Cell Biology.

[19]  P. Agostinis,et al.  Immunogenic versus tolerogenic phagocytosis during anticancer therapy: mechanisms and clinical translation , 2016, Cell Death and Differentiation.

[20]  A. van den Berg,et al.  CD58 mutations are common in Hodgkin lymphoma cell lines and loss of CD58 expression in tumor cells occurs in Hodgkin lymphoma patients who relapse , 2016, Genes and Immunity.

[21]  N. Kaplowitz,et al.  Questions and controversies: the role of necroptosis in liver disease , 2016, Cell Death Discovery.

[22]  W. Kaiser,et al.  Virus inhibition of RIP3-dependent necrosis. , 2010, Cell host & microbe.

[23]  Zhongmin Liu,et al.  Autophagy induced by DAMPs facilitates the inflammation response in lungs undergoing ischemia-reperfusion injury through promoting TRAF6 ubiquitination , 2017, Cell Death and Differentiation.

[24]  G. Juliusson,et al.  Targeting p53 in vivo: a first-in-human study with p53-targeting compound APR-246 in refractory hematologic malignancies and prostate cancer. , 2012, Journal of clinical oncology : official journal of the American Society of Clinical Oncology.

[25]  D. de Ruysscher,et al.  Inducers of immunogenic cancer cell death. , 2013, Cytokine & growth factor reviews.

[26]  T. Kaufmann,et al.  BH3 mimetics efficiently induce apoptosis in mouse basophils and mast cells. , 2018 .

[27]  S. Valentini,et al.  Functionality and opposite roles of two interleukin 4 haplotypes in immune cells , 2017, Genes and Immunity.

[28]  V. Dötsch,et al.  Intrinsic aggregation propensity of the p63 and p73 TI domains correlates with p53R175H interaction and suggests further significance of aggregation events in the p53 family , 2016, Cell Death and Differentiation.

[29]  Lorenzo Galluzzi,et al.  Molecular mechanisms of regulated necrosis. , 2014, Seminars in cell & developmental biology.

[30]  R. Fåhraeus,et al.  p53-mediated suppression of BiP triggers BIK-induced apoptosis during prolonged endoplasmic reticulum stress , 2017, Cell Death and Differentiation.

[31]  F. Kurreeman,et al.  Inflammatory genes TNFα and IL6 display no signs of increased H3K4me3 in circulating monocytes from untreated rheumatoid arthritis patients , 2017, Genes and Immunity.

[32]  D. Kirn,et al.  From ONYX-015 to armed vaccinia viruses: the education and evolution of oncolytic virus development. , 2007, Current cancer drug targets.

[33]  A. Bergmann,et al.  Intercellular cannibalism fuels tumor growth , 2017, Cell Death and Differentiation.

[34]  M. Napoli,et al.  The p53 family orchestrates the regulation of metabolism: physiological regulation and implications for cancer therapy , 2016, British Journal of Cancer.

[35]  L. Kenner,et al.  When the guardian sleeps: Reactivation of the p53 pathway in cancer. , 2017, Mutation research.

[36]  W. Gu,et al.  Ferroptosis as a p53-mediated activity during tumour suppression , 2015, Nature.

[37]  H. Sytwu,et al.  DNA demethylation of the TIM-3 promoter is critical for its stable expression on T cells , 2016, Genes and Immunity.

[38]  B. Stockwell,et al.  Synthetic lethal screening identifies compounds activating iron-dependent, nonapoptotic cell death in oncogenic-RAS-harboring cancer cells. , 2008, Chemistry & biology.

[39]  Sara A. Grimm,et al.  The novel p53 target TNFAIP8 variant 2 is increased in cancer and offsets p53-dependent tumor suppression , 2016, Cell Death and Differentiation.

[40]  L. Zitvogel,et al.  Chemotherapy-induced antitumor immunity requires formyl peptide receptor 1 , 2015, Science.

[41]  D. Bartlett,et al.  Oncolytic Immunotherapy: Dying the Right Way is a Key to Eliciting Potent Antitumor Immunity , 2014, Front. Oncol..

[42]  Antonina Rait,et al.  Phase I study of a systemically delivered p53 nanoparticle in advanced solid tumors. , 2013, Molecular therapy : the journal of the American Society of Gene Therapy.

[43]  Alexei Degterev,et al.  Identification of RIP1 kinase as a specific cellular target of necrostatins. , 2008, Nature chemical biology.

[44]  D. Hanahan,et al.  Hallmarks of Cancer: The Next Generation , 2011, Cell.

[45]  B. Stockwell,et al.  Loss of cysteinyl-tRNA synthetase (CARS) induces the transsulfuration pathway and inhibits ferroptosis induced by cystine deprivation , 2015, Cell Death and Differentiation.

[46]  G. Cohen,et al.  S55746 is a novel orally active BCL-2 selective and potent inhibitor that impairs hematological tumor growth , 2018, Oncotarget.

[47]  Rainer Schmidt,et al.  The cornified envelope: a model of cell death in the skin , 2005, Nature Reviews Molecular Cell Biology.

[48]  Patrick Legembre,et al.  The apoptotic members CD95, BclxL, and Bcl-2 cooperate to promote cell migration by inducing Ca2+ flux from the endoplasmic reticulum to mitochondria , 2016, Cell Death and Differentiation.

[49]  Matthew E. Welsch,et al.  Pharmacological inhibition of cystine–glutamate exchange induces endoplasmic reticulum stress and ferroptosis , 2014, eLife.

[50]  S. Gore,et al.  Hypomethylating agent combination strategies in myelodysplastic syndromes: hopes and shortcomings , 2017, Leukemia & lymphoma.

[51]  P. Vandenabeele,et al.  Immunogenic Apoptotic Cell Death and Anticancer Immunity. , 2016, Advances in experimental medicine and biology.

[52]  C. Hetz,et al.  BCL-2 family: integrating stress responses at the ER to control cell demise , 2017, Cell Death and Differentiation.

[53]  L. Galluzzi,et al.  Activating autophagy to potentiate immunogenic chemotherapy and radiation therapy , 2017, Nature Reviews Clinical Oncology.

[54]  L. Vassilev,et al.  In Vivo Activation of the p53 Pathway by Small-Molecule Antagonists of MDM2 , 2004, Science.

[55]  O. Florey,et al.  Cancer cell cannibalism: Multiple triggers emerge for entosis. , 2018, Biochimica et biophysica acta. Molecular cell research.

[56]  D. Zacks,et al.  FAS apoptotic inhibitory molecule 2 is a stress-induced intrinsic neuroprotective factor in the retina , 2017, Cell Death and Differentiation.

[57]  L. Galluzzi,et al.  Regulated cell death and adaptive stress responses , 2016, Cellular and Molecular Life Sciences.

[58]  M. Overholtzer,et al.  V-ATPase and osmotic imbalances activate endolysosomal LC3 lipidation , 2015, Autophagy.

[59]  R. Grosse,et al.  G-protein-coupled receptor signaling and polarized actin dynamics drive cell-in-cell invasion , 2014, eLife.

[60]  T. Nguyen,et al.  Association of a functional TNF variant with Plasmodium falciparum parasitaemia in a congolese population , 2017, Genes and Immunity.

[61]  Matthew E. Welsch,et al.  Regulation of Ferroptotic Cancer Cell Death by GPX4 , 2014, Cell.

[62]  Darjus F. Tschaharganeh,et al.  Non-Cell-Autonomous Tumor Suppression by p53 , 2013, Cell.

[63]  A. Ashkenazi,et al.  From basic apoptosis discoveries to advanced selective BCL-2 family inhibitors , 2017, Nature Reviews Drug Discovery.

[64]  J. Wolchok,et al.  Immune Checkpoint Blockade in Cancer Therapy. , 2015, Journal of clinical oncology : official journal of the American Society of Clinical Oncology.

[65]  Hailin Zhao,et al.  Role of necroptosis in the pathogenesis of solid organ injury , 2015, Cell Death and Disease.

[66]  Maria M. M. Santos,et al.  An Update on MDMX and Dual MDM2/X Inhibitors. , 2018, Current topics in medicinal chemistry.

[67]  M. Mclaughlin,et al.  Distinct p53 Transcriptional Programs Dictate Acute DNA-Damage Responses and Tumor Suppression , 2011, Cell.

[68]  T. Kaufmann,et al.  BH3 mimetics efficiently induce apoptosis in mouse basophils and mast cells , 2017, Cell Death and Differentiation.

[69]  R. Aqeilan,et al.  Negative regulation of the Hippo pathway by E3 ubiquitin ligase ITCH is sufficient to promote tumorigenicity. , 2011, Cancer research.

[70]  Toru Okamoto,et al.  The pseudokinase MLKL mediates necroptosis via a molecular switch mechanism. , 2013, Immunity.

[71]  I. Amelio,et al.  Cell death pathology: cross-talk with autophagy and its clinical implications. , 2011, Biochemical and biophysical research communications.

[72]  Cole M. Haynes,et al.  Autophagy machinery mediates macroendocytic processing and entotic cell death by targeting single membranes , 2011, Nature Cell Biology.

[73]  D. Vučić,et al.  Diverse ubiquitin linkages regulate RIP kinases-mediated inflammatory and cell death signaling , 2017, Cell Death and Differentiation.

[74]  Benjamin J. Raphael,et al.  Mutational landscape and significance across 12 major cancer types , 2013, Nature.

[75]  A. Richardson,et al.  A non-genetic route to aneuploidy in human cancers , 2011, Nature Cell Biology.

[76]  T. Vanden Berghe,et al.  Disruption of HSP90 Function Reverts Tumor Necrosis Factor-induced Necrosis to Apoptosis* , 2003, The Journal of Biological Chemistry.

[77]  William C Hahn,et al.  Identification of genotype-selective antitumor agents using synthetic lethal chemical screening in engineered human tumor cells. , 2003, Cancer cell.

[78]  T. Vanden Berghe,et al.  The Role of the Kinases RIP1 and RIP3 in TNF-Induced Necrosis , 2010, Science Signaling.

[79]  M. Gonen,et al.  Ultrasmall nanoparticles induce ferroptosis in nutrient-deprived cancer cells and suppress tumour growth , 2016, Nature nanotechnology.

[80]  R. Valdés-Mas,et al.  Chronic lymphocytic leukemia: looking into the dark side of the genome , 2015, Cell Death and Differentiation.

[81]  J. Bertin,et al.  Toll-like Receptor 3-mediated Necrosis via TRIF, RIP3, and MLKL* , 2013, The Journal of Biological Chemistry.

[82]  D. Lane,et al.  Drugging the p53 pathway: understanding the route to clinical efficacy , 2014, Nature Reviews Drug Discovery.

[83]  G. Tonon,et al.  p63 sustains self-renewal of mammary cancer stem cells through regulation of Sonic Hedgehog signaling , 2015, Proceedings of the National Academy of Sciences.

[84]  K. Wiman,et al.  Targeting mutant p53 for efficient cancer therapy , 2017, Nature Reviews Cancer.

[85]  A. Levine,et al.  TAp73 opposes tumor angiogenesis by promoting hypoxia-inducible factor 1α degradation , 2014, Proceedings of the National Academy of Sciences.

[86]  V. Rotter,et al.  p53 on the crossroad between regeneration and cancer , 2016, Cell Death and Differentiation.

[87]  J. Gray,et al.  Glutamine sensitivity analysis identifies the xCT antiporter as a common triple-negative breast tumor therapeutic target. , 2013, Cancer cell.

[88]  R. Advani,et al.  Phase 1 study of the safety, pharmacokinetics, and antitumour activity of the BCL2 inhibitor navitoclax in combination with rituximab in patients with relapsed or refractory CD20+ lymphoid malignancies , 2015, British journal of haematology.

[89]  C. Panagiotopoulos,et al.  Pre-diagnostic genotyping identifies T1D subjects with impaired Treg IL-2 signaling and an elevated proportion of FOXP3+IL-17+ cells , 2017, Genes and Immunity.

[90]  Y. Pekarsky,et al.  Novel insights in molecular mechanisms of CLL. , 2012, Current pharmaceutical design.

[91]  I. Amelio,et al.  MicroRNAs and p63 in epithelial stemness , 2014, Cell Death and Differentiation.

[92]  V. Rotter,et al.  Post-translational regulation of p53 function through 20S proteasome-mediated cleavage , 2017, Cell Death and Differentiation.

[93]  S. Inoue,et al.  TAp73 depletion accelerates aging through metabolic dysregulation. , 2012, Genes & development.

[94]  G. Melino,et al.  Cell death pathology: the war against cancer. , 2011, Biochemical and biophysical research communications.

[95]  T. Vanden Berghe,et al.  How do we fit ferroptosis in the family of regulated cell death? , 2017, Cell Death and Differentiation.

[96]  Matthias Evert,et al.  p53-Dependent Nestin Regulation Links Tumor Suppression to Cellular Plasticity in Liver Cancer , 2014, Cell.

[97]  W. Fiers,et al.  Tumour necrosis factor-induced necrosis versus anti-Fas-induced apoptosis in L929 cells. , 1997, Cytokine.

[98]  Brian J. Smith,et al.  Structure-guided design of a selective BCL-X(L) inhibitor. , 2013, Nature chemical biology.

[99]  Hao Xiong,et al.  Substantial susceptibility of chronic lymphocytic leukemia to BCL2 inhibition: results of a phase I study of navitoclax in patients with relapsed or refractory disease. , 2012, Journal of clinical oncology : official journal of the American Society of Clinical Oncology.

[100]  Abhishek D. Garg,et al.  Immunogenic cell death and DAMPs in cancer therapy , 2012, Nature Reviews Cancer.

[101]  L. Lam,et al.  ABT-199, a potent and selective BCL-2 inhibitor, achieves antitumor activity while sparing platelets , 2013, Nature Medicine.

[102]  I. Amelio,et al.  The p53 family and the hypoxia-inducible factors (HIFs): determinants of cancer progression. , 2015, TIBS -Trends in Biochemical Sciences. Regular ed.

[103]  W. Fiers,et al.  Dual Signaling of the Fas Receptor: Initiation of Both Apoptotic and Necrotic Cell Death Pathways , 1998, The Journal of experimental medicine.

[104]  Todd D. Westergard,et al.  The p53-cathepsin axis cooperates with ROS to activate programmed necrotic death upon DNA damage , 2009, Proceedings of the National Academy of Sciences.

[105]  G. Kroemer,et al.  The tumor suppressor protein p53 and the ferroptosis network , 2019, Free radical biology & medicine.

[106]  Peter Vandenabeele,et al.  Necroptosis: the release of damage-associated molecular patterns and its physiological relevance. , 2013, Immunity.

[107]  D. Tang,et al.  Ferroptosis: process and function , 2016, Cell Death and Differentiation.

[108]  Carol Prives,et al.  Mutant p53: one name, many proteins. , 2012, Genes & development.

[109]  M. Konopleva,et al.  Pathways and mechanisms of venetoclax resistance , 2017, Leukemia & lymphoma.

[110]  L. Zitvogel,et al.  Immunogenic cell death in cancer and infectious disease , 2016, Nature Reviews Immunology.

[111]  A. Strasser,et al.  The MCL1 inhibitor S63845 is tolerable and effective in diverse cancer models , 2016, Nature.

[112]  G. Calin,et al.  p63–microRNA feedback in keratinocyte senescence , 2012, Proceedings of the National Academy of Sciences.

[113]  M. Rehm,et al.  Bcl-2-Ome – a database and interactive web service for dissecting the Bcl-2 interactome , 2016, Cell Death and Differentiation.

[114]  Jedd D. Wolchok,et al.  Cancer immunotherapy using checkpoint blockade , 2018, Science.

[115]  G. Dorn Novel pharmacotherapies to abrogate postinfarction ventricular remodeling , 2009, Nature Reviews Cardiology.

[116]  M. V. Vander Heiden,et al.  Environmental cystine drives glutamine anaplerosis and sensitizes cancer cells to glutaminase inhibition , 2017, eLife.

[117]  Nicolai J. Birkbak,et al.  Tracking the Evolution of Non‐Small‐Cell Lung Cancer , 2017, The New England journal of medicine.

[118]  L. Attardi,et al.  Unravelling mechanisms of p53-mediated tumour suppression , 2014, Nature Reviews Cancer.

[119]  H. Inoue,et al.  Multimodal immunogenic cancer cell death as a consequence of anticancer cytotoxic treatments , 2013, Cell Death and Differentiation.

[120]  James M. Wilson Gendicine: The First Commercial Gene Therapy Product; Chinese Translation of Editorial , 2005 .

[121]  A. Strasser,et al.  Anti-apoptotic proteins BCL-2, MCL-1 and A1 summate collectively to maintain survival of immune cell populations both in vitro and in vivo , 2017, Cell Death and Differentiation.

[122]  B. Stockwell,et al.  Ferroptosis: A Regulated Cell Death Nexus Linking Metabolism, Redox Biology, and Disease , 2017, Cell.

[123]  T. Olsson,et al.  VAV1 regulates experimental autoimmune arthritis and is associated with anti-CCP negative rheumatoid arthritis , 2017, Genes and Immunity.

[124]  Scott W. Lowe,et al.  Putting p53 in Context , 2017, Cell.

[125]  U. Moll,et al.  Depleting stabilized GOF mutant p53 proteins by inhibiting molecular folding chaperones: a new promise in cancer therapy , 2016, Cell Death and Differentiation.

[126]  L. Wood,et al.  A p53 Super-tumor Suppressor Reveals a Tumor Suppressive p53-Ptpn14-Yap Axis in Pancreatic Cancer. , 2017, Cancer cell.

[127]  Y. Zhao,et al.  Downregulation of ZBTB24 hampers the G0/1- to S-phase cell-cycle transition via upregulating the expression of IRF-4 in human B cells , 2016, Genes and Immunity.

[128]  Lynette M. Smith,et al.  Epistatic effect of TLR −1, −6 and −10 Polymorphisms on Organic Dust-Mediated Cytokine Response , 2016, Genes and Immunity.

[129]  G. Blandino,et al.  Reactivation of mutant p53 by a dietary-related compound phenethyl isothiocyanate inhibits tumor growth , 2016, Cell Death and Differentiation.

[130]  C. Croce,et al.  Isoform-specific monoubiquitination, endocytosis, and degradation of alternatively spliced ErbB4 isoforms , 2008, Proceedings of the National Academy of Sciences.

[131]  R. Cencic,et al.  Repression of p53-target gene Bbc3/PUMA by MYSM1 is essential for the survival of hematopoietic multipotent progenitors and contributes to stem cell maintenance , 2016, Cell Death and Differentiation.

[132]  V. Peperzak,et al.  Functional disparities among BCL-2 members in tonsillar and leukemic B-cell subsets assessed by BH3-mimetic profiling , 2016, Cell Death and Differentiation.

[133]  I. Amelio,et al.  p73 Alternative Splicing: Exploring a Biological Role for the C-Terminal Isoforms , 2018, Journal of molecular biology.

[134]  Scott J. Dixon,et al.  Ferroptosis: bug or feature? , 2017, Immunological reviews.

[135]  R. Brigelius-Flohé,et al.  Glutathione peroxidases. , 2013, Biochimica et biophysica acta.

[136]  D. Green,et al.  Synchronized renal tubular cell death involves ferroptosis , 2014, Proceedings of the National Academy of Sciences.

[137]  R. Majeti,et al.  Isocitrate dehydrogenase 1 and 2 mutations induce BCL-2 dependence in acute myeloid leukemia , 2015, Nature Medicine.

[138]  W. Kaiser,et al.  Viral modulation of programmed necrosis. , 2013, Current opinion in virology.

[139]  Dolores Diaz,et al.  Exploiting selective BCL-2 family inhibitors to dissect cell survival dependencies and define improved strategies for cancer therapy , 2015, Science Translational Medicine.

[140]  Qiang Sun,et al.  Impaired formation of homotypic cell-in-cell structures in human tumor cells lacking alpha-catenin expression , 2015, Scientific Reports.

[141]  V. Rotter,et al.  Novel p53 target genes secreted by the liver are involved in non-cell-autonomous regulation , 2015, Cell Death and Differentiation.

[142]  Y. Pekarsky,et al.  Molecular basis of CLL. , 2010, Seminars in cancer biology.

[143]  Alexei Degterev,et al.  Chemical inhibitor of nonapoptotic cell death with therapeutic potential for ischemic brain injury , 2005, Nature chemical biology.

[144]  Polly Matzinger,et al.  Hydrophobicity: an ancient damage-associated molecular pattern that initiates innate immune responses , 2004, Nature Reviews Immunology.

[145]  A. Levine,et al.  Mutant p53 Disrupts Mammary Tissue Architecture via the Mevalonate Pathway , 2012, Cell.

[146]  C. Croce,et al.  MicroRNAs in diagnosis and prognosis in cancer: what does the future hold? , 2010, Pharmacogenomics.