Anti-EGFR Therapy to Treat Metastatic Colorectal Cancer: Not for All

Efficacy and Safety of Anti-EGFR Therapy Rechallenge in Metastatic Colorectal Cancer: A Systematic Review and Meta-Analysis

BACKGROUND

Colorectal cancer (CRC) represents the second leading cause of cancer-related mortality worldwide, with a significant portion of patients presenting with metastatic disease at diagnosis. Resistance to initial anti-EGFR therapy, a key treatment for RAS wild-type metastatic CRC, remains a major challenge. This study aimed to assess the efficacy and safety of rechallenge with anti-EGFR therapy in patients with metastatic CRC who have progressed after prior treatments.

METHODS

A systematic search was conducted across PubMed, Web of Science, Cochrane, and Scopus. Studies were included if they were randomized controlled trials (RCTs) or observational studies involving patients with EGFR-mutated metastatic CRC who received anti-EGFR therapy as a rechallenge. Endpoints included objective response rate (ORR), disease control rate (DCR), and the incidence of adverse events. Statistical analyses were performed using the DerSimonian/Laird random effect model, with heterogeneity assessed via I2 statistics. R, version 4.2.3, was used for statistical analyses.

RESULTS

Fourteen studies were included with 520 patients; 50.3% were male, and the median age was 63 years old. The median progression-free survival (mPFS) ranged between 2.4 and 4.9 months, while the median overall survival (mOS) ranged from 5 to 17.8 months. Our pooled analysis demonstrated an objective response rate (ORR) of 17.70% (95% CI, 8.58-26.82%) and a disease control rate (DCR) of 61.72% (95% CI, 53.32-70.11%), both with significant heterogeneity (I2, 84% and 80%, respectively; p < 0.01). In the subgroup analysis, cetuximab showed an ORR of 18.31% (95% CI, 4.67-31.94%), and panitumumab an ORR of 10.9% (95% CI, 0.00-26.82%), while the combination of both resulted in an ORR of 29.24% (95% CI, 0.00-65.84%). For DCR, cetuximab resulted in 62.1% (95% CI, 49.32-74.87%), panitumumab in 63.05% (95% CI, 52.13-73.97%), and the combination in 60.34% (95% CI, 31.92-88.77%), all with significant heterogeneity. Adverse events included anemia (15.39%), diarrhea (4.20%), hypomagnesemia (6.40%), neutropenia (22.57%), and skin rash (13.22%).

CONCLUSIONS

Rechallenge with anti-EGFR therapy in metastatic CRC patients shows moderate efficacy with manageable safety profiles. These findings highlight the need for careful patient selection and monitoring to optimize outcomes. Further studies are warranted to refine strategies for maximizing the therapeutic benefits of anti-EGFR rechallenge.

CRISPR/Cas9-mediated silencing of CD44: unveiling the role of hyaluronic acid-mediated interactions in cancer drug resistance

A comprehensive overview of CD44 (CD44 Molecule (Indian Blood Group)), a cell surface glycoprotein, and its interaction with hyaluronic acid (HA) in drug resistance mechanisms across various types of cancer is provided, where CRISPR/Cas9 gene editing was utilized to silence CD44 expression and examine its impact on cancer cell behavior, migration, invasion, proliferation, and drug sensitivity. The significance of the HA-CD44 axis in tumor microenvironment (TME) delivery and its implications in specific cancer types, the influence of CD44 variants and the KHDRBS3 (KH RNA Binding Domain Containing, Signal Transduction Associated 3) gene on cancer progression and drug resistance, and the potential of targeting HA-mediated pathways using CRISPR/Cas9 gene editing technology to overcome drug resistance in cancer were also highlighted.

EGFR-selective activation of CD27 co-stimulatory signaling by a bispecific antibody enhances anti-tumor activity of T cells

A higher density of tumor infiltrating lymphocytes (TILs) in the tumor microenvironment, particularly cytotoxic CD8+ T cells, is associated with improved clinical outcome in various cancers. However, local inhibitory factors can suppress T cell activity and hinder anti-tumor immunity. Notably, TILs from various cancer types express the co-stimulatory Tumor Necrosis Factor receptor CD27, making it a potential target for co-stimulation and re-activation of tumor-infiltrated and tumor-reactive T cells. Anti-cancer therapeutics based on exploiting CD27-mediated T cell co-stimulation have proven safe, but clinical responses remain limited. This is likely because current monoclonal antibodies fail to effectively activate CD27 signaling, as this receptor requires higher-order receptor cross-linking. Here, we report on a bispecific antibody, CD27xEGFR, that targets both CD27 and the tumor antigen, epidermal growth factor receptor (EGFR). By targeting EGFR, which is commonly expressed on carcinomas, CD27xEGFR induced cancer cell-localized crosslinking and activation of CD27. The design of CD27xEGFR includes an Fc-silent domain, which is designed to minimize potential toxicity by reducing Fc gamma receptor-mediated binding and activation of immune cells. CD27xEGFR bound to both of its targets simultaneously and triggered EGFR-restricted co-stimulation of T cells as measured by T cell proliferation, T cell activation markers, cytotoxicity and IFN-γ release. Further, CD27xEGFR augmented T cell cytotoxicity in a panel of artificial antigen-presenting carcinoma cell line models, leading to Effector-to-Target ratio-dependent elimination of cancer cells. Taken together, we present the in vitro characterization of a novel bispecific antibody that re-activates T cell immunity in EGFR-expressing cancers through targeted co-stimulation of CD27.

A perfused multi-well bioreactor platform to assess tumor organoid response to a chemotherapeutic gradient

There is an urgent need to develop new therapies for colorectal cancer that has metastasized to the liver and, more fundamentally, to develop improved preclinical platforms of colorectal cancer liver metastases (CRCLM) to screen therapies for efficacy. To this end, we developed a multi-well perfusable bioreactor capable of monitoring CRCLM patient-derived organoid response to a chemotherapeutic gradient. CRCLM patient-derived organoids were cultured in the multi-well bioreactor for 7 days and the subsequently established gradient in 5-fluorouracil (5-FU) concentration resulted in a lower IC₅₀ in the region near the perfusion channel versus the region far from the channel. We compared behaviour of organoids in this platform to two commonly used PDO culture models: organoids in media and organoids in a static (no perfusion) hydrogel. The bioreactor IC₅₀ values were significantly higher than IC₅₀ values for organoids cultured in media whereas only the IC₅₀ for organoids far from the channel were significantly different than organoids cultured in the static hydrogel condition. Using finite element simulations, we showed that the total dose delivered, calculated using area under the curve (AUC) was similar between platforms, however normalized viability was lower for the organoid in media condition than in the static gel and bioreactor. Our results highlight the utility of our multi-well bioreactor for studying organoid response to chemical gradients and demonstrate that comparing drug response across these different platforms is nontrivial.

SERS characterization of colorectal cancer cell surface markers upon anti-EGFR treatment

Colorectal cancer (CRC) is the third most diagnosed and the second lethal cancer worldwide. Approximately 30-50% of CRC are driven by mutations in the KRAS oncogene, which is a strong negative predictor for response to anti-epidermal growth factor receptor (anti-EGFR) therapy. Examining the phenotype of KRAS mutant and wild-type (WT) CRC cells in response to anti-EGFR treatment may provide significant insights into drug response and resistance. Herein, surface-enhanced Raman spectroscopy (SERS) assay was applied to phenotype four cell surface proteins (EpCAM, EGFR, HER2, HER3) in KRAS mutant (SW480) and WT (SW48) cells over a 24-day time course of anti-EGFR treatment with cetuximab. Cell phenotypes were obtained using Raman reporter-coated and antibody-conjugated gold nanoparticles (SERS nanotags), where a characteristic Raman spectrum was generated upon single laser excitation, reflecting the presence of the targeted surface marker proteins. Compared to the KRAS mutant cells, KRAS WT cells were more sensitive to anti-EGFR treatment and displayed a significant decrease in HER2 and HER3 expression. The SERS results were validated with flow cytometry, confirming the SERS assay is promising as an alternative method for multiplexed characterization of cell surface biomarkers using a single laser excitation system.

Predictive and Therapeutic Implications of a Novel PLCγ1/SHP2-Driven Mechanism of Cetuximab Resistance in Metastatic Colorectal Cancer

PURPOSE

Cetuximab is an EGFR-targeted therapy approved for the treatment of RAS wild-type (WT) metastatic colorectal cancer (mCRC). However, about 60% of these patients show innate resistance to cetuximab. To increase cetuximab efficacy, it is crucial to successfully identify responder patients, as well as to develop new therapeutic approaches to overcome cetuximab resistance.

EXPERIMENTAL DESIGN

We evaluated the value of EGFR effector phospholipase C gamma 1 (PLCγ1) in predicting cetuximab responses, by analyzing progression-free survival (PFS) of a multicentric retrospective cohort of 94 treated patients with mCRC (log-rank test and Cox regression model). Furthermore, we used in vitro and zebrafish xenotransplant models to identify and target the mechanism behind PLCγ1-mediated resistance to cetuximab.

RESULTS

In this study, levels of PLCγ1 were found increased in RAS WT tumors and were able to predict cetuximab responses in clinical samples and in vitro and in vivo models. Mechanistically, PLCγ1 expression was found to bypass cetuximab-dependent EGFR inhibition by activating ERK and AKT pathways. This novel resistance mechanism involves a noncatalytic role of PLCγ1 SH2 tandem domains in the propagation of downstream signaling via SH2-containing protein tyrosine phosphatase 2 (SHP2). Accordingly, SHP2 inhibition sensitizes PLCγ1-resistant cells to cetuximab.

CONCLUSIONS

Our discoveries reveal the potential of PLCγ1 as a predictive biomarker for cetuximab responses and suggest an alternative therapeutic approach to circumvent PLCγ1-mediated resistance to cetuximab in patients with RAS WT mCRC. In this way, this work contributes to the development of novel strategies in the medical management and treatment of patients with mCRC.

Highly specific detection of KRAS single nucleotide polymorphism by asymmetric PCR/SERS assay

The molecular diagnosis of KRAS mutations has become crucial for clinical decision-making in colorectal cancer (CRC) treatments. Currently, the common methods for detecting mutations are based on quantitative PCR, DNA sequencing and droplet digital PCR (ddPCR), which require expensive specialized equipment and testing reagents. Herein, we propose a simple and specific strategy by integrating asymmetric PCR with surface-enhanced Raman spectroscopy (Asy-PCR/SERS) for the detection of KRAS G12V mutation, one of the most common driver mutations in CRC. To discriminate mutant targets from non-targets, Asy-PCR was applied to obtain single-stranded DNA (ssDNA) with unequal amounts of forward and reverse primers, subsequently, detection of the target mutant ssDNA amplicons was attempted by hybridization with Raman reporter-coded and allele-specific oligonucleotide-functionalized gold nanoparticles (SERS nanotags). The oligo encoding of the KRAS G12V mutant sequence could be identified by using a portable Raman spectrometer where the characteristic spectra of SERS nanotags indicate the presence of mutant targets. The Asy-PCR/SERS method showed high specificity and sensitivity for identifying as few as 0.1% mutant alleles of KRAS G12V mutation from non-target sequences. Using colorectal polyp biopsies, we demonstrated that Asy-PCR/SERS assay could distinguish KRAS G12V (c.35G > T) and KRAS G12D (c.35G > A) which occur at the same nucleotide location. As KRAS G12V is a driver oncogene in other cancers including lung, pancreatic, ovarian and endometrial cancers, the proposed assay shows great potential for application in additional tumor streams.

Landscape of Current Targeted Therapies for Advanced Colorectal Cancer

Colorectal cancer (CRC) is one of the most frequent and lethal cancer types worldwide. While surgery with chemotherapy and radiotherapy remains the only curative approach for localized CRC, for metastatic disease the therapeutic landscape has significantly evolved over the last years. Development and approval of novel targeted therapies, such as monoclonal antibodies against EGFR and VEGF, have significantly increased the median survival of patients with metastatic disease, with some trials reporting a benefit over 40 months. Increasing accessibility of high throughput sequencing has unraveled several new therapeutic targets. Actionable alterations, such as HER2 overexpression, BRAF mutations, and NTRK fusions, are currently available in metastatic disease, providing significant therapeutic opportunities for these patients, while new emerging agents, as immune checkpoint inhibitors, promise better treatment options in the near future. In this chapter, an overview of established and future CRC targeted therapies in the clinical setting is provided, as well as their mechanism of action, limitations, and future applicability.

High-Density, Targeted Monitoring of Tyrosine Phosphorylation Reveals Activated Signaling Networks in Human Tumors

Tyrosine phosphorylation (pTyr) plays a pivotal role in signal transduction and is commonly dysregulated in cancer. As a result, profiling tumor pTyr levels may reveal therapeutic insights critical to combating disease. Existing discovery and targeted mass spectrometry-based methods used to monitor pTyr networks involve a tradeoff between broad coverage of the pTyr network, reproducibility in target identification across analyses, and accurate quantification. To address these limitations, we developed a targeted approach, termed "SureQuant pTyr," coupling low input pTyr enrichment with a panel of isotopically labeled internal standard peptides to guide data acquisition of low-abundance tyrosine phosphopeptides. SureQuant pTyr allowed for reliable quantification of several hundred commonly dysregulated pTyr targets with high quantitative accuracy, improving the robustness and usability of targeted mass spectrometry assays. We established the clinical applicability of SureQuant pTyr by profiling pTyr signaling levels in human colorectal tumors using minimal sample input, characterizing patient-specific oncogenic-driving mechanisms. While in some cases pTyr profiles aligned with previously reported proteomic, genomic, and transcriptomic molecular characterizations, we highlighted instances of new insights gained using pTyr characterization and emphasized the complementary nature of pTyr measurements with traditional biomarkers for improving patient stratification and identifying therapeutic targets. The turn-key nature of this approach opens the door to rapid and reproducible pTyr profiling in research and clinical settings alike and enables pTyr-based measurements for applications in precision medicine. SIGNIFICANCE: SureQuant pTyr is a mass spectrometry-based targeted method that enables sensitive and selective targeted quantitation of several hundred low-abundance tyrosine phosphorylated peptides commonly dysregulated in cancer, including oncogenic signaling networks.

A molecular subtype of colorectal cancers initiates independently of epidermal growth factor receptor and has an accelerated growth rate mediated by IL10-dependent anergy

Although epidermal growth factor receptor (EGFR)-targeted therapies are approved for colorectal cancer (CRC) treatment, only 15% of CRC patients respond to EGFR inhibition. Here, we show that colorectal cancers (CRC) can initiate and grow faster through an EGFR-independent mechanism, irrespective of the presence of EGFR, in two different mouse models using tissue-specific ablation of Egfr. The growth benefit in the absence of EGFR is also independent of Kras status. An EGFR-independent gene expression signature, also observed in human CRCs, revealed that anergy-inducing genes are overexpressed in EGFR-independent polyps, suggesting increased infiltration of anergic lymphocytes promotes an accelerated growth rate that is partially caused by escape from cell-mediated immune responses. Many genes in the EGFR-independent gene expression signature are downstream targets of interleukin 10 receptor alpha (IL10RA). We further show that IL10 is detectable in serum from mice with EGFR-independent colon polyps. Using organoids in vitro and Src ablation in vivo, we show that IL10 contributes to growth of EGFR-independent CRCs, potentially mediated by the well-documented role of SRC in IL10 signaling. Based on these data, we show that the combination of an EGFR inhibitor with an anti-IL10 neutralizing antibody results in decreased cell proliferation in organoids and in decreased polyp size in pre-clinical models harboring EGFR-independent CRCs, providing a new therapeutic intervention for CRCs resistant to EGFR inhibitor therapies.

Extended RAS Analysis of the Phase III EPIC Trial: Irinotecan + Cetuximab Versus Irinotecan as Second-Line Treatment for Patients with Metastatic Colorectal Cancer

BACKGROUND

The multicenter, open-label, randomized, phase III EPIC study (EMR 062202-025) investigated cetuximab plus irinotecan versus irinotecan in patients with epidermal growth factor receptor-detectable metastatic colorectal cancer (mCRC) that progressed on first-line fluoropyrimidine- and oxaliplatin-based chemotherapy; we report the outcomes of patients with RAS-wild-type (wt) disease.

MATERIALS AND METHODS

Available DNA samples from RAS-unselected patients (n = 1,164 of 1,298 [89.7%]) were reanalyzed for RAS mutations using beads, emulsion, amplification, and magnetics. Baseline characteristics, efficacy, safety, and poststudy therapy were assessed. RAS-wt status was defined as a mutated RAS allele frequency of ≤5%, with all relevant alleles being analyzable.

RESULTS

Baseline characteristics were comparable between the groups (n = 452 patients with RAS-wt mCRC; cetuximab plus irinotecan n = 231, irinotecan n = 221) and between the RAS-wt and RAS-unselected populations. In the cetuximab plus irinotecan versus irinotecan arms, median overall survival was 12.3 versus 12.0 months, median progression-free survival (PFS) was 5.4 versus 2.6 months, and objective response rate (ORR) was 29.4% versus 5.0%, respectively. Quality of life (QoL) was improved in the cetuximab plus irinotecan arm. Serious adverse events occurred in 45.4% (cetuximab plus irinotecan) and 42.4% (irinotecan) of patients. In total, 47.1% of patients in the irinotecan arm received subsequent cetuximab therapy.

CONCLUSION

PFS, ORR, and QoL were improved with cetuximab plus irinotecan as a second-line treatment in patients with RAS-wt mCRC, confirming that cetuximab-based therapy is suitable in this population. Almost half of patients in the irinotecan arm received poststudy cetuximab, masking a potential overall survival benefit of cetuximab addition.

IMPLICATIONS FOR PRACTICE

Cetuximab is approved for the treatment of RAS-wild-type metastatic colorectal cancer (mCRC). In this retrospective analysis of the phase III EPIC study (cetuximab plus irinotecan vs. irinotecan alone as second-line treatment in patients with RAS-unselected mCRC), the subgroup of patients with RAS-wild-type mCRC who received cetuximab plus irinotecan had improved progression-free survival, objective response rate, and quality of life compared with the RAS-unselected population. These findings suggest that cetuximab-based therapy is a suitable second-line treatment for patients with RAS-wild-type mCRC.

Undetectable RAS-Mutant Clones in Plasma: Possible Implication for Anti-EGFR Therapy and Prognosis in Patients With RAS-Mutant Metastatic Colorectal Cancer

PURPOSE

Combining cetuximab with chemotherapy provides clinical benefit to 60% of the patients with RAS wild-type (RAS-wt) metastatic colorectal cancer (mCRC). This pilot study investigated the efficacy of cetuximab-based chemotherapy in a sample of patients (40%) with RAS mutation (RAS-mt) in their primary tumor whose circulating tumor DNA (ctDNA) was RAS-wt.

MATERIALS AND METHODS

The occurrence of Kirsten rat sarcoma viral oncogene homolog (KRAS), neuroblastoma rat sarcoma viral oncogene homolog (NRAS), V-raf murine sarcoma viral oncogene homolog B1 (BRAF), and PI3KCA mutations was determined in ctDNA by using a new ultrasensitive analysis based on mass spectrometry detection. All consenting patients with confirmed RAS-mt mCRC had disease progression on previous chemotherapy that contained no anti–epidermal growth factor receptor (EGFR). The patients with RAS-wt ctDNA received cetuximab + fluorouracil, leucovorin, and irinotecan (FOLFIRI), whereas those with RAS-mt ctDNA were treated with the oncologist’s choice of therapy.

RESULTS

Of 16 registered patients, 11 were male and five female. They were age 48 to 81 years, and they had unresectable metastatic adenocarcinoma from the colon (n = 11) or rectum (n = 5), with a median of two metastatic sites. They had received a median number of three previous chemotherapy protocols. Plasma genotyping identified RAS-mt in seven patients (44%) and RAS-wt in nine patients (56%). In the patients with wt ctDNA, objective tumor response rate was 50.0%, including one complete response and four partial responses after a median number of 6 courses of cetuximab + FOLFIRI (range, 1 to 16 courses). Two of the nine patients had stable disease, and two had progressive disease. No grade 3 to 4 toxicities were encountered. One-year survival rates were 60.0% for the patients with RAS-wt ctDNA and 17.9% for those with RAS-mt ctDNA. Median overall survival times were not reached and 4.7 months, respectively.

CONCLUSION

Patients with RAS-mt mCRC whose plasma biopsies contained RAS-wt could benefit from cetuximab-based therapy, a hypothesis to be tested in a prospective randomized trial.

An approach using Caenorhabditis elegans screening novel targets to suppress tumour cell proliferation

OBJECTIVES

Tumour cell proliferation requires high metabolism to meet the bioenergetics and biosynthetic needs. Dauer in Caenorhabditis elegans is characterized by lower metabolism, and we established an approach with C elegans to find potential tumour therapy targets.

MATERIALS AND METHODS

RNAi screening was used to find dauer-related genes, and these genes were further analysed in glp-1(-) mutants for tumour-suppressing testing. The identified tumour-related genes were verified in clinical tumour tissues.

RESULTS

The lifespan of glp-1(-) mutants was found to be extended by classical dauer formation signalling. Then, 61 of 287 kinase-coding genes in Caenorhabditis elegans were identified as dauer-related genes, of which 27 were found to be homologous to human oncogenes. Furthermore, 12 dauer-related genes were randomly selected for tumour-suppressing test, and six genes significantly extended the lifespan of glp-1(-) mutants. Of these six genes, F47D12.9, W02B12.12 and gcy-21 were newly linked to dauer formation. These three new dauer-related genes significantly suppressed tumour cell proliferation and thus extended the lifespan of glp-1(-) mutants in a longevity- or dauer-independent manner. The mRNA expression profiles indicated that these dauer-related genes trigged similar low metabolism pattern in glp-1(-) mutants. Notably, the expression of homolog gene DCAF4L2/F47D12.9, TSSK6/W02B12.12 and NPR1/gcy-21 was found to be higher in glioma compared with adjacent normal tissue. In addition, the high expression of TSSK6/W02B12.12 and NPR1/gcy-21 correlated with a worse survival in glioma patients.

CONCLUSIONS

Dauer gene screening in combination with tumour-suppressing test in glp-1(-) mutants provided a useful approach to find potential targets for tumour therapy via suppressing tumour cell proliferation and rewiring tumour cell metabolism.

Necroptosis, ADAM proteases and intestinal (dys)function

Recently, an unexpected connection between necroptosis and members of the a disintegrin and metalloproteinase (ADAM) protease family has been reported. Necroptosis represents an important cell death routine which helps to protect from viral, bacterial, fungal and parasitic infections, maintains adult T cell homeostasis and contributes to the elimination of potentially defective organisms before parturition. Equally important for organismal homeostasis, ADAM proteases control cellular processes such as development and differentiation, immune responses or tissue regeneration. Notably, necroptosis as well as ADAM proteases have been implicated in the control of inflammatory responses in the intestine. In this review, we therefore provide an overview of the physiology and pathophysiology of necroptosis, ADAM proteases and intestinal (dys)function, discuss the contribution of necroptosis and ADAMs to intestinal (dys)function, and review the current knowledge on the role of ADAMs in necroptotic signaling.

Predictive biomarkers in clinical practice: State of the art and perspectives in solid tumors

The discovery of molecular alterations that play key functions in pathways of tumor growth and survival have changed the treatment approach of several solid tumors. A number of biomarkers are now approved in clinical practice for the selection of patients to be treated with the specific targeted drug, and others are currently under study. None of these biomarkers are perfect and they have a number of biases. Novel treatment approaches, such as immunotherapy, require the development of more complex biomarker combinations as the mechanism of action of these drugs involves multiple parameters. In this short communication the principal approved biomarkers in solid tumors are discussed, with attention to the novel promising biomarkers that will be developed in the future.

HER2 as a Predictive Biomarker and Treatment Target in Colorectal Cancer

The prognosis of metastatic colorectal cancer (mCRC) is poor. Cetuximab and panitumumab, 2 anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (mAbs), improve the overall survival of patients with RAS wild-type mCRC. However, not all patients with RAS wild-type mCRC will respond to anti-EGFR mAbs. Several retrospective trials suggest that human epidermal growth factor receptor 2 (HER2) amplification could be a predictive biomarker of resistance to anti-EGFR mAbs in patients with metastatic RAS and RAF wild-type mCRC. Dual HER2 inhibition with trastuzumab plus lapatinib or pertuzumab has shown promising preliminary anti-tumoral efficacy in RAS wild-type mCRC. Although these findings need to be confirmed in randomized trials, the data strongly support that HER2 is an actionable gene in CRC and provide the scientific rationale to test HER2 status on a routine basis in this disease. In this review, we discuss the predictive value of HER2 activation in CRC as well as its potential role as a treatment target.

Precision Medicine in Colorectal Surgery

This article reviews advances in precision medicine for colorectal carcinoma that have influenced screening and treatment, and potentially prevention. Advances in molecular techniques have made it possible for better patient selection for therapies; therefore, mutational analysis should be performed at diagnosis to guide treatment. Future efforts should focus on validating these treatments in specific subgroups and on understanding the mechanisms of resistance to therapies to enable treatment optimization, promote efficacy, and reduce treatment costs and toxicities.