Targeting the EGFR signalling pathway in metastatic colorectal cancer.

Epidermal growth factor receptor (EGFR) and its activated downstream signalling pathways play a crucial role in colorectal cancer development and progression. After four decades of preclinical, translational, and clinical research, it has been shown that blocking the EGFR signalling pathway at different molecular levels represents a fundamental therapeutic strategy for patients with metastatic colorectal cancer. Nevertheless, the efficacy of molecularly targeted therapies is inescapably limited by the insurgence of mechanisms of acquired cancer cell resistance. Thus, in the era of precision medicine, a deeper understanding of the complex molecular landscape of metastatic colorectal cancer is required to deliver the best treatment choices to all patients. Major efforts are currently ongoing to improve patient selection, improve the efficacy of available treatments targeting the EGFR pathway, and develop novel combination strategies to overcome therapy resistance within the continuum of care of metastatic colorectal cancer.

Anti-EGFR Rechallenge in Patients With Refractory ctDNA RAS/BRAF wt Metastatic Colorectal Cancer: A Nonrandomized Controlled Trial.

Importance: The available evidence regarding anti-epidermal growth factor receptor (EGFR) inhibitor rechallenge in patients with refractory circulating tumor DNA (ctDNA) RAS/BRAF wild-type (wt) metastatic colorectal cancer (mCRC) is derived from small retrospective and prospective studies. Objective: To evaluate the efficacy of anti-EGFR rechallenge in patients with refractory ctDNA RAS/BRAF wt mCRC. Design, Setting, and Participants: This nonrandomized controlled trial used a pooled analysis of individual patient data from patients with RAS/BRAF wt ctDNA mCRC enrolled in 4 Italian trials (CAVE, VELO, CRICKET, and CHRONOS) and treated with anti-EGFR rechallenge between 2015 and 2022 (median [IQR] follow-up, 28.1 [25.8-35.0] months). Intervention: Patients received anti-EGFR rechallenge therapy, including cetuximab plus avelumab, trifluridine-tipiracil plus panitumumab, irinotecan plus cetuximab, or panitumumab monotherapy. Main Outcomes and Measures: Overall survival (OS), progression-free survival (PFS), overall response rate (ORR), and disease control rate (DCR) were calculated. Exploratory subgroup analysis evaluating several clinical variables was performed. Safety was reported. Results: Overall, 114 patients with RAS/BRAF wt ctDNA mCRC (median [IQR] age, 61 [29-88] years; 66 men [57.9%]) who received anti-EGFR rechallenge as experimental therapy (48 received cetuximab plus avelumab, 26 received trifluridine-tipiracil plus panitumumab, 13 received irinotecan plus cetuximab, and 27 received panitumumab monotherapy) were included in the current analysis. Eighty-three patients (72.8%) had received 2 previous lines of therapy, and 31 patients (27.2%) had received 3 or more previous lines of therapy. The ORR was 17.5% (20 patients), and the DCR was 72.3% (82 patients). The median PFS was 4.0 months (95% CI, 3.2-4.7 months), and the median OS was 13.1 months (95% CI, 9.5-16.7 months). The subgroup of patients without liver involvement had better clinical outcomes. The median PFS was 5.7 months (95% CI, 4.8-6.7 months) in patients without liver metastasis compared with 3.6 months (95% CI, 3.3-3.9 months) in patients with liver metastasis (hazard ratio, 0.56; 95% CI, 0.37-0.83; P = .004). The median OS was 17.7 months (95% CI, 13-22.4 months) in patients without liver metastasis compared with 11.5 months (95% CI, 9.3-13.9 months) in patients with liver metastasis (hazard ratio, 0.63; 95% CI, 0.41-0.97; P = .04). Treatments showed manageable toxic effects. Conclusions and Relevance: These findings suggest that anti-EGFR rechallenge therapy has promising antitumor activity in patients with refractory ctDNA RAS/BRAF wt mCRC. Within the limitation of a subgroup analysis, the absence of liver metastases was associated with significant improved survival. Trial Registration: ClinicalTrials.gov Identifiers: NCT02296203; NCT04561336; NCT03227926; NCT05468892.

PBMCs as Tool for Identification of Novel Immunotherapy Biomarkers in Lung Cancer.

BACKGROUND: Lung cancer (LC), including both non-small (NSCLC) and small (SCLC) subtypes, is currently treated with a combination of chemo- and immunotherapy. However, predictive biomarkers to identify high-risk patients are needed. Here, we explore the role of peripheral blood mononuclear cells (PBMCs) as a tool for novel biomarkers searching. METHODS: We analyzed the expression of the cGAS-STING pathway, a key DNA sensor that activates during chemotherapy, in PBMCs from LC patients divided into best responders (BR), responders (R) and non-responders (NR). The PBMCs were whole exome sequenced (WES). RESULTS: PBMCs from BR and R patients of LC cohorts showed the highest levels of STING (p < 0.0001) and CXCL10 (p < 0.0001). From WES, each subject had at least 1 germline/somatic alteration in a DDR gene and the presence of more DDR gene mutations correlated with clinical responses, suggesting novel biomarker implications. Thus, we tested the effect of the pharmacological DDR inhibitor (DDRi) in PBMCs and in three-dimensional spheroid co-culture of PBMCs and LC cell lines; we found that DDRi strongly increased cGAS-STING expression and tumor infiltration ability of immune cells in NR and R patients. Furthermore, we performed FACS analysis of PBMCs derived from LC patients from the BR, R and NR cohorts and we found that cytotoxic T cell subpopulations displayed the highest STING expression. CONCLUSIONS: cGAS-STING signaling activation in PBMCs may be a novel potential predictive biomarker for the response to immunotherapy and high levels are correlated with a better response to treatment along with an overall increased antitumor immune injury.

All for one: Collaboration between dermatologist, radiation oncologist and radiologist in the clinical management of "difficult to treat" non melanoma skin cancer.

This series introduces the clinical management of difficult-to-treat non-melanoma skin cancers (NMSCs) through a multidisciplinary approach, emphasizing the integration of dermoscopy and Ultra high-frequency ultrasound (UHFUS) for accurate diagnosis and treatment planning, particularly in cases referred for radiotherapy (RT). Dermoscopy aids in diagnosing both pigmented and non-pigmented skin lesions, guiding treatment margins and reducing the benign-to-malignant biopsy ratio. UHFUS provides valuable insights into tumor size, depth, and vascularity, complementing clinical evaluations and assisting in RT planning. Three challenging cases are presented, highlighting the pivotal role of dermoscopy and UHFUS in decision-making and treatment optimization. Collaboration between dermatologists, radiation oncologists, and radiologists enhances diagnostic accuracy, tailoring treatment plans to individual patient needs and preferences, ultimately improving patient outcomes and experience. The integration of these imaging techniques holds promise for optimizing non-surgical treatments like RT and monitoring treatment progress, offering a personalized approach to NMSC management.

The JAK-STAT Pathway as a Therapeutic Strategy in Cancer Patients with Immune Checkpoint Inhibitor-Induced Colitis: A Narrative Review.

Immunotherapy has emerged as a pivotal component in the treatment of various malignancies, encompassing lung, skin, gastrointestinal, and head and neck cancers. The foundation of this therapeutic approach lies in immune checkpoint inhibitors (ICI). While ICIs have demonstrated remarkable efficacy in impeding the neoplastic progression of these tumours, their use may give rise to substantial toxicity, notably in the gastrointestinal domain, where ICI colitis constitutes a significant aspect. The optimal positioning of Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway inhibitors in the therapeutic management of ICI colitis remains unclear. Numerous reports have highlighted notable improvements in ICI colitis through the application of pan-JAK-STAT inhibitors, with tofacitinib, in particular, reporting evident clinical remission of colitis. The precise mechanism by which JAK-STAT inhibitors may impact the pathogenetic process of ICI colitis remains inadequately understood. However, there is speculation regarding their potential role in modulating memory resident CD8+ T lymphocytes. The elucidation of this mechanism requires further extensive and robust evidence, and ongoing JAK-STAT-based trials are anticipated to contribute valuable insights.

Oral Adverse Events Associated with BRAF and MEK Inhibitors in Melanoma Treatment: A Narrative Literature Review.

BACKGROUND: Melanoma cancer represents the most lethal type of skin cancer originating from the malignant transformation of melanocyte cells. Almost 50% of melanomas show the activation of BRAF mutations. The identification and characterization of BRAF mutations led to the development of specific drugs that radically changed the therapeutic approach to melanoma. METHODS: We conducted a narrative review of the literature according to a written protocol before conducting the study. This article is based on previously conducted studies. We identified articles by searching electronic databases (Medline, Google Scholar and PubMed). We used a combination of "melanoma", "Braf-Mek inhibitors", " targeted therapy" and "oral side effects". RESULTS: Eighteen studies were reported in this article showing the relationship between the use of targeted therapy in melanoma cancer and the development of oral side effects, such as mucositis, hyperkeratosis and cellular proliferation. CONCLUSION: Targeted therapy plays an important role in the treatment of melanoma cancer, showing a notable increase in response rate, prolonged progression-free survival and overall survival in BRAF-mutated melanoma patients. Oral side effects represent a common finding over the course of treatment. However, these adverse effects can be easily managed in a multidisciplinary approach involving collaboration between medical oncologists and dental doctors.

The Role of Sentinel Node Biopsy in the Era of Adjuvant Therapy for Melanoma.

Sentinel lymph node biopsy (SLNB) is a surgical procedure aimed to detect nodal metastases in patients with clinically occult disease. Since the advent of new systemic therapies, its role in melanoma has been extensively debated over the last years. In this article, three possible scenarios are discussed, considering the SLNB impact on the management of melanoma patients. First, pT1b and pT2a patients with negative SLNB (stages IA and IB) and those with positive SLNB (stage IIIA) would all not benefit from adjuvant treatment. Therefore, SLNB might be avoided in these categories of patients. Second, in IIB and IIC, melanoma patients are already candidates for adjuvant treatment; therefore, SLNB in patients with T3b, T4a, or T4b melanoma would not change treatment decisions. On the other end of the spectrum, patients with pT2b and pT3a melanomas (clinical stage IIA) represent the only two groups whose management would be significantly affected by the SLNB status, being adjuvant therapy only indicated for SLN-positive patients. Further studies are needed to investigate which melanoma patient deserves SLNB.

Characteristics of Real-World Patients with High-Risk BRAFV600E/K-Mutated Melanoma Receiving Adjuvant Treatment with Dabrafenib Plus Trametinib After Surgical Resection, Through the Italian Managed Access Program.

Purpose: Real-world data from patients with BRAFV600-mutated, resected, stage III melanoma treated with dabrafenib plus trametinib as adjuvant targeted therapy are limited, and it is important to gain an understanding of the characteristics of this patient population, as well as of the patient journey. Here we aimed to describe the characteristics, dosage reductions and discontinuations in patients with BRAFV600E/K-mutated melanoma receiving adjuvant dabrafenib plus trametinib after surgical resection through an Italian managed access program (MAP). Patients and Methods: Eligible patients had completely resected cutaneous melanoma with confirmed BRAF V600E or V600K mutation, or initially resectable lymph node recurrence after a diagnosis of stage I or II melanoma. The starting dose of dabrafenib and trametinib was 150 mg twice daily and 2 mg once daily, respectively. Results: A total of 557 patients received dabrafenib plus trametinib through the MAP (stage III resected disease at inclusion, 554). Median age was 54.0 years, and 40.2% of patients were female. The proportion of all treated patients who required a dose reduction was low (10.8%) as was the proportion of patients who discontinued treatment (13.5%). The main reason for treatment discontinuation was adverse events (36.0%). Conclusion: New treatments, including BRAF-targeted therapies and immunotherapy, have transformed the natural history of melanoma. This is the largest study to date describing patients treated with dabrafenib plus trametinib in routine clinical practice in Italy between 2018 and 2019. Results highlight the characteristics of the patients treated and their journey, as well as the tolerable safety profile of dabrafenib plus trametinib in a real-world patient population.

Combined blockade of mTOR and p21-activated kinases pathways prevents tumour growth in KRAS-mutated colorectal cancer.

BACKGROUND: The identification of novel therapeutic strategies for metastatic colorectal cancer (mCRC) patients harbouring KRAS mutations represents an unmet clinical need. In this study, we aimed to clarify the role of p21-activated kinases (Paks) as therapeutic target for KRAS-mutated CRC. METHODS: Paks expression and activation levels were evaluated in a cohort of KRAS-WT or -mutated CRC patients by immunohistochemistry. The effects of Paks inhibition on tumour cell proliferation and signal transduction were assayed by RNAi and by the use of three pan-Paks inhibitors (PF-3758309, FRAX1036, GNE-2861), evaluating CRC cells, spheroids and tumour xenografts' growth. RESULTS: Paks activation positively correlated with KRAS mutational status in both patients and cell lines. Moreover, genetic modulation or pharmacological inhibition of Paks led to a robust impairment of KRAS-mut CRC cell proliferation. However, Paks prolonged blockade induced a rapid tumour adaptation through the hyper-activation of the mTOR/p70S6K pathway. The addition of everolimus (mTOR inhibitor) prevented the growth of KRAS-mut CRC tumours in vitro and in vivo, reverting the adaptive tumour resistance to Paks targeting. CONCLUSIONS: In conclusion, our results suggest the simultaneous blockade of mTOR and Pak pathways as a promising alternative therapeutic strategy for patients affected by KRAS-mut colorectal cancer.

Italian nivolumab Expanded Access Programme in melanoma adjuvant setting: patient outcomes and safety profile.

INTRODUCTION: The CheckMate 238 randomised study demonstrated the relevant benefit in terms of recurrence-free survival (RFS) of nivolumab versus ipilimumab in resected stage IIIB-C or IV melanoma patients with a tolerable safety profile. MATERIALS AND METHODS: From November 2018 to June 2019, 611 patients with stage III and IV resected melanoma were enroled to receive nivolumab as part of an Italian Expanded Access Programme (EAP). According to stages, 77% were stage III while 141 (23%) were stage IV with no evidence of disease (NED). Among stage III, 121 patients had IIIA (19.8%). RESULTS: After a median follow-up of 23 months, the RFS in the Intention-to-Treat (ITT) population was 76.6% at 1 year and 59.6% at 2 years; 1- and 2-year distant metastasis-free survival were 83.7% and 71.2%, respectively. The overall survival rate in the ITT population was 93.8% at 1 year and 85.5% at 2 years. No significant differences in RFS were observed according to BRAF status. Treatment-related adverse events of grades 3-4 occurred in 11.5% of patients. CONCLUSION: This paper reports the results of the Italian Nivolumab EAP in the adjuvant setting of stage III and IV NED melanoma patients. Our results confirm in a real-life setting the clinical activity and safety of nivolumab reported in the CheckMate238 registrative/pivotal. The enroled cohort of 611 patients highlights the relevant clinical need in this setting, also confirmed by the very short accrual time, representing one of the largest series reported as adjuvant EAP with the longest follow-up.

Panitumumab plus trifluridine/tipiracil as anti-EGFR rechallenge therapy in patients with refractory RAS wild-type metastatic colorectal cancer: Overall survival and subgroup analysis of the randomized phase II VELO trial.

The randomized phase II VELO trial showed that the addition of panitumumab to trifluridine/tipiracil significantly improves progression-free survival (PFS) as compared to trifluridine/tipiracil in third-line therapy in patients with refractory RAS wild-type (WT) metastatic colorectal cancer (mCRC). With longer follow-up, final overall survival results and posttreatment subgroup analysis are presented. Sixty-two patients with refractory RAS WT mCRC were randomly assigned to receive, as third-line therapy, trifluridine/tipiracil alone (arm A) or in combination with panitumumab (arm B). Primary endpoint was PFS; secondary endpoints included overall survival (OS) and overall response rate (ORR). Median OS was 13.1 months (95% CI 9.5-16.7) in arm A compared to 11.6 months (95% CI 6.3-17.0) in arm B (HR: 0.96, 95% CI 0.54-1.71, P = .9). To evaluate the impact of subsequent lines of treatment, subgroup analysis was performed for the 24/30 patients in arm A, that received fourth-line therapy after disease progression. Median PFS was 4.1 months (95% CI 1.44-6.83) for 17 patients treated with anti-EGFR rechallenge as compared to 3.0 months (95% CI 1.61-4.31) for seven patients that received other therapies (HR: 0.29, 95% CI 0.10-0.85, P = .024). Median OS from the start of fourth-line treatment was 13.6 months (95% CI 7.2-20), and 5.1 months (95% CI 1.8-8.3) for patients treated with anti-EGFR rechallenge vs other therapies, respectively (HR: 0.30, 95% CI 0.11-0.81, P = .019). Final results of the VELO trial support the role of anti-EGFR rechallenge in the continuum of care of patients with RAS/BRAF WT mCRC.

Magnetic Resonance Imaging Evaluation of Bone Metastases Treated with Radiotherapy in Palliative Intent: A Multicenter Prospective Study on Clinical and Instrumental Evaluation Assessment Concordance (MARTE Study).

Metastasis to bone is a common occurrence among epithelial tumors, with a high incidence rate in the Western world. As a result, bone lesions are a significant burden on the healthcare system, with a high morbidity index. These injuries are often symptomatic and can lead to functional limitations, which in turn cause reduced mobility in patients. Additionally, they can lead to secondary complications such as pathological fractures, spinal cord compression, hypercalcemia, or bone marrow suppression. The treatment of bone metastases requires collaboration between multiple healthcare professionals, including oncologists, orthopedists, neurosurgeons, physiatrists, and radiotherapists. The primary objective of this study is to evaluate the correlation between two methods used to assess local control. Specifically, the study aims to determine if a reduction in the volume of bone lesions corresponds to better symptomatic control in the clinical management of patients, and vice versa. To achieve this objective, the study evaluates morphological criteria by comparing pre- and post-radiotherapy treatment imaging using MRI and RECIST 1.1 criteria. MRI without contrast is the preferred diagnostic imaging method, due to its excellent tolerance by patients, the absence of exposure to ionizing radiation, and the avoidance of paramagnetic contrast media side effects. This imaging modality allows for accurate assessment of bone lesions. One of the secondary objectives of this study is to identify potentially useful parameters that can distinguish patients into two classes: "good" and "poor" responders to treatment, as reported by previous studies in the literature. These parameters can be evaluated from the imaging examinations by analyzing morphological changes and radiomic features on different sequences, such as T1, STIR (short tau inversion recovery), and DWI-MRI (diffusion-weighted).

Panitumumab Plus Trifluridine-Tipiracil as Anti-Epidermal Growth Factor Receptor Rechallenge Therapy for Refractory RAS Wild-Type Metastatic Colorectal Cancer: A Phase 2 Randomized Clinical Trial.

Importance: Current third-line therapies for patients with metastatic colorectal cancer (MCRC) have limited efficacy. Rechallenge with epidermal growth factor receptor (EGFR) inhibitors for RAS wild-type (WT) MCRC may be valuable for these patients. Objective: To compare the anti-EGFR monoclonal antibody panitumumab plus standard-of-care trifluridine-tipiracil with trifluridine-tipiracil alone as third-line therapy for RAS WT MCRC. Design, Setting, and Participants: This phase 2 randomized clinical trial (RCT) was conducted in 7 Italian centers from June 2019 to April 2022. Patients with refractory RAS WT MCRC who had a partial or complete response to first-line chemotherapy plus an anti-EGFR monoclonal antibody and an anti-EGFR drug-free interval of 4 or more months during second-line therapy were included. Interventions: Patients were randomized 1:1 to receive panitumumab plus trifluridine-tipiracil or trifluridine-tipiracil alone. Main Outcomes and Measures: The primary end point was progression-free survival (PFS). Circulating tumor DNA (ctDNA) extended sequence variation analysis was performed in a subgroup of patients. Results: Of 62 included patients, 31 received panitumumab plus trifluridine-tipiracil (19 [61.3%] male; median age, 65 years [range, 39-81 years]) and 31 received trifluridine-tipiracil alone (17 [54.8%] male; median age, 66 years [range, 32-82 years]). The primary end point was met. Median PFS was 4.0 months (95% CI, 2.8-5.3 months) in the panitumumab plus trifluridine-tipiracil arm vs 2.5 months (95% CI, 1.4-3.6 months) in the trifluridine-tipiracil only (hazard ratio [HR], 0.48; 95% CI, 0.28-0.82; P = .007). Pretreatment plasma RAS/BRAF WT ctDNA identified patients obtaining prolonged clinical benefit with panitumumab plus trifluridine-tipiracil compared with trifluridine-tipiracil, with PFS rates at 6 months of 38.5% vs 13.0% and at 12 months of 15.4% vs 0%. A ctDNA liquid-biopsy extended mutation analysis by FoundationOne Liquid CDx (profiling 324 genes) was performed in a subgroup of patients with baseline plasma RAS/BRAF WT ctDNA; in 15 of 23 patients (65.2%) whose tumors were WT for KRAS, NRAS, BRAFV600E, EGFR, ERBB2, MAP2K1, and PIK3CA, median PFS was 6.4 months (95% CI, 3.7-9.2 months). Within this group of 15 patients, 2 (13.3%) had partial response, 11 (73.3%) had stable disease, and 2 (13.3%) had disease progression as best response. Conclusions and Relevance: In this RCT, third-line treatment with the anti-EGFR monoclonal antibody panitumumab plus the standard-of-care trifluridine-tipiracil resulted in improved PFS compared with treatment with trifluridine-tipiracil alone among patients with refractory RAS WT MCRC. The findings support the clinical utility of liquid biopsy-guided anti-EGFR rechallenge therapy for refractory RAS WT MCRC. Trial Registration: ClinicalTrials.gov Identifier: NCT05468892.

Application of CytoMatrix for the diagnosis of melanoma metastases on FNA cytology samples: Performance of a novel cell block method.

BACKGROUND: The management of cytological samples can significantly impact diagnostic interpretation. Cell blocks (CB) are a popular method due to their ability to provide additional morphological information and be used for immunocytochemistry and molecular tests. Recently, a new CB technique called the synthetic matrix CytoMatrix (CM) has been introduced, which can gather and hold cytological material within its three-dimensional structure. METHODS: In this study, 40 cytological samples from patients with melanoma metastases were analyzed to evaluate the diagnostic performance of CM compared to another CB method used in the laboratory. The researchers assessed the morphological adequacy of the two techniques, as well as their performance in immunocytochemical analysis and molecular. RESULTS: This study showed that CM was quicker and equally effective compared to the other method, with the laboratory technician having less of an impact on the CM approach across all passages. Additionally, all CMs were adequate, whereas the other method was adequate in 90% of cases. Immunocytochemistry confirmed the diagnosis of melanoma metastases in all cases, and all 40 CMs and 36 of the other method were adequate for fluorescence in situ hybridization analysis. CONCLUSION: CM is a low-time-consuming technology that is unaffected by technicians during all setup phases, making it simpler to standardize the procedure. Moreover, a low loss of diagnostic cells ensures greater benefits for morphological analysis, immunocytochemistry, and molecular testing. Overall, the study highlights the potential of CM as a valuable technique for managing cytological samples.

The Pattern of Progression to First-Line Treatment with Dabrafenib and Trametinib in Patients with Unresectable or Metastatic, BRAF-Mutated, Cutaneous Melanoma: Results of the Observational T-WIN Study.

In patients with B-RAF-mutated cutaneous melanoma, targeted therapies are the treatment of choice to achieve a rapid response. In this multicentric, prospective, observational study, patients with B-RAF-mutated cutaneous melanoma who were treated with dabrafenib and trametinib were categorized in two cohorts (cohort A: limited disease (n = 104) and cohort B: bulky disease (n = 97)) according to lactate dehydrogenase levels. The primary endpoint was the progression pattern; the secondary endpoints were overall survival (OS), progression-free survival (PFS), and safety data. From baseline to time of progression, there was a progression from nodal to other sites of disease in cohort A and from skin and nodal to other sites in cohort B. In both the cohorts, the number of involved organs and metastases at each location decreased. The median OS was 32.4 months (95% CI: 20.1 months (not estimable)) for cohort A, and 10.5 months (95% CI: 8.3-14.4 months) for cohort B; median PFS was 12.4 months (95% CI: 10.9-17.0 months) for cohort A, and 8.1 months (95% CI: 6.3-9.4 months) for cohort B. No new safety signals were reported. This study describes the patterns of first-line treatment progression with dabrafenib and trametinib in Italian clinical practice. The effectiveness and safety data were consistent with previous trials and extended to a real-world heterogeneous population.

Pretreatment Plasma Circulating Tumor DNA RAS/BRAF Mutational Status in Refractory Metastatic Colorectal Cancer Patients Who Are Candidates for Anti-EGFR Rechallenge Therapy: A Pooled Analysis of the CAVE and VELO Clinical Trials.

Rechallenge with anti-EGFR drugs represents a promising strategy in refractory RAS/BRAF wild-type (WT) metastatic colorectal cancer (mCRC). We performed the pooled analysis of the CAVE and VELO studies to evaluate the percentage of patients with WT circulating tumor DNA (ctDNA) tumors and the association of mutational status with time from the last anti-EGFR drug administration. At baseline, 97/129 patients had RAS/BRAF WT plasma ctDNA, while 32/129 had RAS/BRAF mutated plasma ctDNA. Median anti-EGFR drug-free interval was 10.6 (CI 95%, 8.9-13.4) months in the plasma RAS/BRAF mutant group as compared to 13.0 (CI 95%, 11.1-16.6) months in RAS/BRAF WT group (p = 0.169). To investigate the time window of the RAS/BRAF mutant cancer cell clone disappearance, descriptive analysis using different time points was performed. No difference in the proportion of patients whose baseline plasma ctDNA was RAS/BRAF WT or mutated was found between 4 and 18 months since the last administration of anti-EGFR drugs. In contrast, 38/44 of patients with anti-EGFR drug-free interval of 18 months or more displayed a ctDNA RAS/BRAF WT status. Taken together, these results shows that the length of anti-EGFR free interval is not a sufficient criterion for patient selection, supporting the role of liquid biopsies for improving treatment efficacy.

Antitumor Efficacy of Dual Blockade with Encorafenib + Cetuximab in Combination with Chemotherapy in Human BRAFV600E-Mutant Colorectal Cancer.

PURPOSE: Encorafenib + cetuximab (E+C) is an effective therapeutic option in chemorefractory BRAFV600E metastatic colorectal cancer (mCRC). However, there is a need to improve the efficacy of this molecular-targeted therapy and evaluate regimens suitable for untreated BRAFV600E in patients with mCRC. EXPERIMENTAL DESIGN: We performed a series of in vivo studies using BRAFV600E mCRC tumor xenografts. Mice were randomized to receive 5-fluoruracil (5-FU), irinotecan, or oxaliplatin regimens (FOLFIRI or FOLFOX), (E+C) or the combination. Patients received long-term treatment until disease progression, with deescalation strategies used to mimic maintenance therapy. Transcriptomic changes after progression on cytotoxic chemotherapy or targeted therapy were assessed. RESULTS: Antitumor activity of either FOLFIRI or E+C was better as first-line treatment as compared with second-line, with partial cross-resistance seen between a cytotoxic regimen and targeted therapy with an average 62% loss of efficacy for FOLFIRI after E+C and a 45% loss of efficacy of E+C after FOLFIRI (P < 0.001 for both). FOLFIRI-treated models had upregulation of epithelial-mesenchymal transition (EMT) and MAPK pathway activation, where E+C treated models had suppressed MAPK signaling. In contrast, with chemotherapy with E+C, EMT and MAPK signaling remained suppressed. FOLFOX or FOLFIRI, each in combination with E+C, were the most active first-line treatments as compared with E+C or to chemotherapy alone. Furthermore, FOLFOX in combination with E+C as first-line induction therapy, followed by E+C ± 5-FU as maintenance therapy, was the most effective strategy for long-term disease control. CONCLUSIONS: These results support the combination of cytotoxic chemotherapy and molecular-targeted therapy as a promising therapeutic approach in the first-line treatment of BRAFV600E mCRC.