Wild-type BRAF Research Articles

Surgical strategy for colorectal cancer with synchronous liver and extrahepatic metastases: A scoring system and decision tree model.

The role of hepatectomy in a specific group of patients with synchronous colorectal cancer with liver metastases (SCRLM) and synchronous extrahepatic disease (SEHD) is still unclear. The aim of this study was to evaluate the efficacy of liver surgery and define the selection criteria for surgical candidates in patients with SCRLM + SEHD. Between July 2007 and October 2018, 475 patients with colorectal cancer with liver metastases (CRLM) who underwent liver resection were retrospectively reviewed. Sixty-five patients with SCRLM + SEHD were identified and included in the study. Clinical pathological data of these patients were analyzed to evaluate the influence on survival. Important prognostic factors were identified by univariate and multivariate analyses. The risk score system and decision tree analysis were generated according to the important prognostic factors for better patient selection. The 5-year survival rate of patients with SCRLM + SEHD was 21.9%. The most important prognostic factors were SCRLM number of more than five, site of SEHD other than the lung only, inability to achieve SCRLM + SEHD R0 resection, and BRAF mutation of cancer cells. The proposed risk score system and decision tree model easily discriminated between patients with different survival rates and identified the profile of suitable surgical patients. Liver surgery should not be a contraindication for patients with SCRLM + SEHD. Patients with complete SCRLM + SEHD R0 resection, SCRLM number less than or equal to five, SEHD confined to the lung only, and wild-type BRAF could have favorable survival outcomes. The proposed scoring system and decision tree model may be beneficial to patient selection in clinical use.

Efficacy of panitumumab in patients with left-sided disease, MSS/MSI-L, and RAS/BRAF WT: A biomarker study of the phase III PARADIGM trial.

3508 Background: The PARADIGM trial (NCT02394795) showed longer median overall survival (OS) with first-line mFOLFOX6 plus panitumumab (PAN) vs bevacizumab (BEV) in patients (pts) with RAS wild type (WT) and left-sided metastatic colorectal cancer (mCRC; 37.9 vs 34.3 months, respectively; hazard ratio [HR], 0.82; P=0.031) and similar OS in right-sided pts (HR 1.09; Yoshino T, et al. ASCO 2022 LBA1). Based on current guideline recommendations regarding clinically relevant biomarkers, here we report clinical outcomes in left-sided mCRC pts with microsatellite stable or microsatellite instability low (MSS/MSI-L) and RAS (KRAS/NRAS)/ BRAF (V600E) WT from PARADIGM. Methods: Baseline plasma circulating tumor DNA (ctDNA; >10 ng/mL and >10 nM DNA) from pts enrolled in the biomarker study (NCT02394834) was assessed using a custom panel (PlasmaSELECT-R 91, PGDx). The efficacy (OS, progression-free survival [PFS], response rate [RR], and curative resection rate [R0]) of PAN plus mFOLFOX6 compared with BEV plus mFOLFOX6 according to RAS, BRAF (V600E), and MSI status and primary tumor location was evaluated. Results: Among 802 pts in the full analysis set, 733 (91%) had evaluable pretreatment samples for ctDNA analysis. Of these pts, 53 (7.2%) and 78 (10.6%) pts had RAS and BRAF ( V600E) mutations, respectively, and 20 (2.7%) pts had MSI high (MSI-H) status. In left-sided mCRC pts with MSS/MSI-L and RAS/ BRAF WT, OS tended to be longer with PAN vs BEV (40.6 [95% CI, 36.3-44.4] vs 34.8 [95% CI, 31.3-41.2] months, respectively; HR, 0.79 [95% CI, 0.64–0.97]). Although PFS was comparable between PAN (13.6 months [95% CI, 12.6–15.3]) and BEV (12.6 months [95% CI, 11.3–14.1]; HR, 0.95 [95% CI, 0.77–1.17]), RR and R0 resection rates were higher with PAN (RR: 83.2% [95% CI, 78.0–87.6]; R0: 18.8% [95% CI: 14.2–24.1]) compared with BEV (RR: 66.4% [95% CI, 60.0–72.3]; R0: 10.0% [95% CI: 6.5–14.5]). OS was similar or inferior to PAN vs BEV regardless of the primary sidedness in pts with MSI-H or RAS/ BRAF mutations (Table). Conclusions: These results support PAN + mFOLFOX6 as a first-line therapy for left-sided pts with MSS/MSI-L and RAS/ BRAF WT. Clinical trial information: NCT02394795 . [Table: see text]

Real-world rates of FDA-approved targeted therapy and immunotherapy prescriptions for patients with metastatic colorectal cancer in the VA’s National Precision Oncology Program (NPOP).

3602 Background: Colorectal cancer is the fourth most common cancer among Veterans and the third leading cause of cancer-related death in the USA. Use of comprehensive genomic profiling (CGP) to guide administration of FDA-approved biomarker directed therapies can improve outcomes among metastatic CRC (mCRC) patients. We sought to compute the rates of actionable biomarkers and prescriptions of associated FDA-approved therapies among Veterans in NPOP. Methods: The NPOP database was queried to identify mCRC patients who had undergone CGP via tissue or liquid biopsy between February 2019 and July 2022 and had one of the following 5 actionable biomarker profiles: NRAS/ KRAS/ BRAF wildtype, BRAF V600E, MSI-H, TMB-H, or NTRK fusion or rearrangement. The VA’s Corporate Data Warehouse (CDW) was queried to extract prescription data for seven FDA-approved biomarker-directed therapies (targeted agents and immune checkpoint inhibitors (ICIs)). Rates of CGP-directed therapy prescriptions were assessed based upon biomarker and patient characteristics (sex, race, ethnicity, and rurality). Results: A total of 908 mCRC patients underwent CGP, with 81.4% bearing colon adenocarcinoma (COAD) and 18.6% rectal adenocarcinoma (READ). Rates of actionable biomarkers associated with FDA-approved therapies were as follows: NRAS/ KRAS/ BRAF wildtype (34.4%), TMB-H (9.6%), BRAF V600E (7.7%), MSI-H (5.6%), TMB-H and MSI-H (5.6%), and NTRK Fusion or rearrangement (0.3%). The combined rates of any actionable variant were 47.4% for COAD and 44.4% for READ patients. Relative to patients without actionable biomarkers, patients with BRAF V600E mutations were more likely to be older and white; patients with NRAS/ KRAS/ BRAF wildtype were more likely to be younger (all p < 0.001). Among the 424 eligible patients, the frequencies of FDA-approved CGP-directed therapy prescriptions were as follows: MSI-H (70.7%), TMB-H (47.4%), NRAS/ KRAS/ BRAF wildtype (38.5%), and BRAF V600E (17.1%). Across all included biomarkers, African Americans (53.4%) were more likely to receive these therapies than whites (36.8%); and patients with prescriptions were more likely to be younger that those without (all p < 0.01). Conclusions: Nearly 30% of patients with MSI-H mCRC did not receive efficacious ICIs, and though disease laterality data was not readily available, a substantial number of eligible patients also did not receive EGFR inhibitors. This underuse of EGFR inhibitors has been reported previously [1].There were racial and age differences in prescription rates. Further studies should evaluate the barriers to prescribing CGP-directed therapies in the care of mCRC patients. Keywords: molecular testing, metastatic colorectal cancer, comprehensive genomic profiling, actionable biomarkers, FDA approved therapies, veterans. [1] Becker et al. 2021 PMID 34250412.

Multicenter analysis of melanoma recurrence pattern and management after adjuvant immunotherapy.

e21573 Background: PD-1 inhibitors improve outcomes in resected stage II-IV melanoma. However, recurrence patterns and prognostic factors are less known. Methods: We conducted a retrospective study in resected stage II-IV melanoma patients (p) treated with adjuvant PD-1 inhibitors (clinical practice or clinical trials) from 5 centers. Demographic, disease characteristics, adjuvant therapy, recurrence, treatment at relapse and outcome were recorded. Descriptive assessment for recurrence patterns and analysis for prognostic factors were performed. Results: From June 2017 to June 2022, 181 p were included. Median age was 59 years [22-81], 57% were male, 85% had cutaneous melanoma, 28% had BRAFV600E mutation. 9 p (5%) presented stage II, 147 (81%) stage III and 25 (14%) stage IV. Ulceration was present in 59% p, mitotic rate >1/mm2 in 84%, Breslow index >3 mm in 65% and elevated LDH in 51%. 81% p received PD-1 inhibitors alone and 19% in combination with other immunotherapies. 52% of p completed treatment, 12% discontinued due to toxicity and 26% due to relapse. 13% of p presented grade 3-4 adverse events and there was a grade 5 myocarditis. With a median follow-up of 18,1 months, 68 (37%) p recurred (Table). Median relapse free survival (RFS) was 48,8 months (95% CI 31,1-66,4). Recurrence was significantly associated with a higher stage, mitotic rate, LDH level and Breslow index, BRAFV600E mutation, non-cutaneous melanoma and delayed initiation of adjuvant immunotherapy in univariate analysis (p<0,05). Stage, non-cutaneous melanoma and initiation of immunotherapy >3 months (16% p) were associated with higher recurrence in multivariate analysis (<0,05). Locoregional recurrence was treated in 23 p with surgery (14p), surgery + RT (7p) or RT alone (2). Systemic recurrence was treated in 50 p: all BRAF mutant p received targeted therapy (24p, 43%) with a disease control rate (DCR) of 91% and a median progression free survival (PFS) of 56 months (95% CI 24,1-NR); BRAF wild type p (26p, 47%) were treated with anti-PD-1 alone (9p) or in combination (7p), anti-CTLA-4 (2p), chemotherapy (1p) or best supportive care (7p), with DCR of 33% and a median PFS of 8 months (95% CI 6,9-10,8). Conclusions: We observed a 37% relapse rate and systemic recurrence were more frequent than locoregional recurrence. Treatment at relapse with targeted therapy in BRAF mutant p achieved higher DCR and PFS than immunotherapy in BRAF wild type p; with better outcomes than previously reported.[Table: see text]

MSI analysis in patients with GIST with lynch syndrome.

e23510 Background: Lynch Syndrome due to mutations in one of DNA mismatch repair (MMR) genes, is found in patients with colon cancer (3%).The mutations in these DNA repair genes induce genetic instability and development of ovarian, endometrial, urothelial, gastrointestinal and biliary tract carcinoma. Methods: In our center, 31 patients with Lynch syndrome are followed in Oncology Department in multidisciplinary team according to regional diagnostic therapeutic assistance paths and international guidelines. Immunohistochemical staining (IC) for mismatch repair proteins (MLH1, MSH2, MSH6, PMS2) and microsatellite instability testing (MSI) by PCR real time easyPGX were performed in colon cancer, genetic testing has been preceded by genetic counseling. When GIST diagnosis occurred in patients with colon cancers and Lynch syndrome, IC and MSI were performed in GIST too. Results: MSI-H has been detected in synchronous colo-rectal cancer in 2 patients with GIST. Pathogenetic germline mutations in MSH2 gene were observed in both patients. In 1 female patient with gist of duodenum (very low risk according to Miettinen classification) with previous endometrial cancer and sincronous PT3N0 rectal cancer, we observed MSI-stable in IC and PCR, KIT/PDGFRα wild type in Next GenSequencing analysis, BRAF wild type (PCR-real time), SDH-B + (IC), NTRK 1 (exon 9-10, exon 1-12 del, exon 12), NTRK 2 (exon 12-15.exon 16-17), exon 14, NTRK 3 (exon 14, exon 15) no gene fusion by PCR-real time (CE.IVD kit easy NTRK). In 1 male patient with ileal GIST (intermediate risk according to Miettinen classification ) with ileal adenocarcinoma pT3N0, we observed KIT exon 11 mutated, MSI-stable in IC, when we repeated the analysis using PCR real time EasyPGX, we observed high instability of microsatellites. Conclusions: For the first time we observed in Lynch Syndrome MSH2 mutated, simolutaneous GIST and colon cancer in the same site of ileum and PCR analisys detected a rare exemple of microsatellite instability in GIST.

Breaking primary checkpoint inhibitor resistance: Interim analysis of a multicenter phase II study by intermittent application of an alkylating agent among patients with metastatic melanoma.

9544 Background: Patients with BRAF wildtype (wt) metastatic melanoma with primary resistance to immune checkpoint inhibitors (ICI) have a dismal prognosis. Chemotherapy has been shown to induce mutations, alter the tumor microenvironment as well as the microbiome, and modulate the immune system. This prospective phase II trial investigates whether two applications of an alkylating agent (dacarbazine/DTIC) can render ICI non-responsive patients with metastatic melanoma responsive to the same checkpoint inhibitor regime. Methods: The PROMIT trial (NCT04225390) targets patients with histologically confirmed BRAFwt metastatic melanoma showing primary resistance to ICI therapy. Applying an optimal two-step design, the uninteresting responder rate was set to 5% with an expected rate of 20%. Response is defined as complete or partial response by week 14 according to RECIST 1.1. Design foresaw 29 assessable patients at first step and 38 patients overall (alpha one-sided 5%, 90% power).After showing primary resistance to ICI, patients received 2 doses of DTIC (850 mg/m2 i.v.) on days 1 and 21, and were subsequently re-exposed to the same ICI therapy they had previously shown resistance to. Results: In total, 38 patients were screened at 4 skin cancer centers. Interim analysis was performed after 29 patients who had received at least one ICI re-exposure were assessable for efficacy. Overall response rate was 24% (90%CI 12-41%) with 7 out of 29 patients showing a partial response; disease control rate was 38%. Application was well tolerated with 16% grade 3 or more adverse events and no new safety signals. Conclusions: Interim analyses results indicate that this approach of a short-term chemotherapy can break resistance in a subgroup of patients and allows us to continue the phase II trial to assess relevance of this treatment approach for metastatic melanoma. Enrolment is ongoing. Clinical trial information: NCT04225390 .

Diffusely Infiltrating Gliomas With Poor Prognosis, TERT Promotor Mutations, and Histological Anaplastic Pleomorphic Xanthoastrocytoma-Like Appearance Classify as Mesenchymal Type of Glioblastoma, IDH-wildtype by Methylation Analysis

BACKGROUND: Pleomorphic xanthoastrocytoma (PXA) (World Health Organization grade II) is classified as a relatively benign and circumscribed glioma; however, anaplastic PXA (APXA, World Health Organization grade III) has a poorer prognosis, and differentiating from glioblastoma can be difficult both histologically and molecularly. OBJECTIVE: To describe the clinical, pathological, and molecular characteristics of diffusely infiltrating gliomas with histological APXA-like features. METHODS: Four diffusely infiltrating gliomas in adult patients histologically diagnosed as APXAs at a single institute were retrospectively reviewed. We analyzed their clinical, radiological, pathological, genetic, epigenetic, and prognostic characteristics. RESULTS: All tumors histologically showed classical characteristic PXA-like appearance with BRAF wildtype, mitotic figure, necrosis, and an increased mindbomb E3 ubiquitin-protein ligase 1 labeling index and were initially diagnosed as APXAs; moreover, they underwent high-grade glioma treatment. Three patients with TERT promotor mutations died within 18 months. These patients' MRIs showed widespread infiltrating fluid-attenuated inversion recovery hyperintense lesions and Gd-enhancing lesions in the bilateral cerebral hemispheres in 2 of the patients. Contrastingly, a patient with the wildtype TERT promotor has survived for 2.5 years without recurrence. MRI revealed an unilateral fluid-attenuated inversion recovery hyperintense and Gd-enhancing lesion. By methylation classifier analysis, all 4 cases clustered toward GBM, IDH-wildtype, mesenchymal type, although one was deemed unclassifiable due to a low calibrated score. CONCLUSION: In diffusely infiltrating gliomas showing histological characteristics of APXA, methylation classification should be performed as these tumors may be difficult to differentiate between glioblastoma, IDH-wildtype by histological or genetic analysis. The aggressive nature of these tumors should be expected, especially in cases that are BRAF-wildtype and TERT promotor mutant.

P173 THERAPEUTIC MANAGEMENT OF FLUOROPYRIMIDINE CARDIOTOXICITY: AN ANECDOTAL CASE

Abstract Background Fluoropirimidine represents one of the staple treatment of metastatic colorectal cancer; chemoterapy–based cardiotoxicity is unfortunately habitual in clinical practice. Raltitrexed could represent a valid alterantive to 5–FU in patients with cardiovascular comorbidities or in which 5–FU Has not been tolerated. Case Report Our patient is a 73 years–old woman, who underwent left colon surgical resection due to subocclusion; a whola body staging was not performed. After surgery, patient underwent CT scan,i n which multiple liver, lung and peritoneal metastases were identified. Biomolecular profiling assessment was perfomed (RAS, BRAF Wild type, DPYD*6 heterozigosis mutation). On January 2020, patient began FOLFIRI + PANITUMUMAB scheme as first line treatment (total cycles perfomed: 15). On January 2021, PD was detected though restaging imaging, and patient was subsequently treated with FOLFOX + BEvacizumab as second line. After 5 cycles, patient developed dyspnoea and palpitation; EKG was performed depicting Atrial fibrillation with heart rate: 73bpm, preserved biventricular systolic function and increased BNP and NT–pro–BNP serum concentration. According to patient’s high thromboembolic risk, oral anticoagulation (NOAC) was administered and multidisciplinary discussion was scheduled. NAO were preferred to Vitamin K antagonists due to drug–drug interactions; the treatment–of–choice was Apixaban 2.5 mg bis in die. Given the fact that aforementioned condition could have been attributed to 5–FU cardiologic toxicity, Raltitrexed was administered in lieu thereof 5–FU once synusal rythm was restored (TOMOX scheme). Bevacizumab administration was restored after a longer waiting (ca 2 months); the patient uderwent systematic and serial cardiologic assessment through clinical and EKG consults. Conclusion Our case report depicts the undelayable necessity of a Multidisciplinar collaboration in which oncologists and cardiologists could propose personalized treatment strategies which ensure correct antitumoral activities without significant and life–threatening toxicities.

The benefit of co-targeting PARP-1 and c-Met on the efficacy of radiotherapy in wild type BRAF melanoma.

Melanoma is known to be a radioresistant cancer. Melanoma radioresistance can be due to several factors such as pigmentation, antioxidant defenses and high Deoxyribonucleic acid (DNA) repair efficacy. However, irradiation induces intracellular translocation of RTKs, including cMet, which regulates response to DNA damage activating proteins and promotes DNA repair. Accordingly, we hypothesized that co-targeting DNA repair (PARP-1) and relevant activated RTKs, c-Met in particular, may radiosensitize wild-type B-Raf Proto-Oncogene, Serine/Threonine Kinase (WTBRAF) melanomas where RTKs are often upregulated. Firstly, we found that PARP-1 is highly expressed in melanoma cell lines. PARP-1 inhibition by Olaparib or its KO mediates melanoma cell sensitivity to radiotherapy (RT). Similarly, specific inhibition of c-Met by Crizotinib or its KO radiosensitizes the melanoma cell lines. Mechanistically, we show that RT causes c-Met nuclear translocation to interact with PARP-1 promoting its activity. This can be reversed by c-Met inhibition. Accordingly, RT associated with the inhibition of both c-Met and PARP-1 resulted in a synergistic effect not only on tumor growth inhibition but also on tumor regrowth control in all animals following the stop of the treatment. We thus show that combining PARP and c-Met inhibition with RT appears a promising therapeutic approach in WTBRAF melanoma.

AB039. SOH23ABS_198. MLH1-deficient colorectal carcinoma with wild type BRAF and MLH1 promoter hypermethylation—an understudied molecular phenotype

Background: Up to 15% of colorectal cancers (CRCs) display microsatellite instability (MSI). MSI is reflective of a deficient mismatch repair (MMR) system (dMMR). dMMR CRC represents a heterogeneous group of diseases with separate tumorigenic pathways. The majority of dMMR CRC is sporadic (>90%) and occurs due to acquired methylation of the MLH1 gene promoter. Sporadic MLH1-deficient CRC is thought to originate in lesions that arise from the serrated neoplasia pathway. Although the presence of the BRAF V600E mutation is characteristic of a sporadic cancer, as many as half of CRCs with MLH1 promoter hypermethylation will lack a BRAF mutation.

Abstract A013: Role of EGFR in KRAS-mediated resistances in colorectal cancer. </title>

Abstract The standard of care therapies for metastatic colorectal cancer (mCRC) patients with wild-type (WT) RAS or BRAF consists of chemotherapy combined with targeted anti-EGFR antibodies. Still, only half of the RAS WT mCRC patients are sensitive to anti-EGFR therapy1, and eventually some of them stop responding due to intrinsic and acquired resistance to anti-EGFR treatment2. Moreover, recent clinical studies have also shown that left-sided mCRC respond better to anti-EGFR treatment for reasons that are still unknown. Studies from our lab and others using genetically engineered mouse models (GEMMs) showed that EGFR expressing tumor-associated myeloid cells release inflammatory cytokines that have a pro-tumorigenic role in CRC3,4. Deletion of EGFR in tumor cells of these mice had no effect in tumor size, whereas deletion of EGFR in myeloid cells impaired CRC development3. Moreover, human CRC biopsies confirmed that presence of EGFR+ myeloid cells is associated with a worse overall survival of mCRC patients. From our results in GEMMs, it seems that the therapeutic action of EGFR inhibitors is mediated via EGFR inhibition in myeloid cells. Assuming that tumor cells are not the primary target of anti-EGFR therapies, it is puzzling that KRAS mutations in tumor cells confer resistance to anti-EGFR treatment in mCRC patients. We hypothesize that epithelial KRAS mutations alter the tumor microenvironment (TME) towards an immunosuppressive milieu. We are testing this hypothesis by comparing expression signatures derived from tumor and stroma of human mCRC biopsies that are WT or mutant for KRAS to elucidate the molecular signature driven by KRAS that explains anti-EGFR treatment resistance. In parallel, we employ CRC mouse models generated by orthotopic implantation of WT and RAS mutant mouse CRC organoids into GEMMs lacking the EGFR in different cell types to mimic right and left-sided metastatic disease. Targets identified in human mCRC patients are being mechanistically validated in organoids and derived tumors by CRISPR/Cas9-mediated genetic engineering. The results of these experiments will be presented. The expected results will provide a better understanding of how anti-EGFR antibodies work, how resistance mechanisms are developed, and possible new treatment combinations for KRAS mutated CRC.

Hashimoto’s Thyroiditis: A Protective Factor against Recurrence in BRAF-Wild Type Differentiated Thyroid Carcinoma

A recent work analyzing the concomitant factors BRAF mutation (risk factor) and Hashimoto's thyroiditis (HT) (protective factor) found that the presence of HT reduced lymph node metastasis in BRAF-mutated papillary thyroid carcinoma. Whether this notion is upheld with respect to disease recurrence and differentiated thyroid carcinoma (DTC), however, is unknown. We aimed to investigate the effect of underlying HT in DTC patients and its influence on recurrence with a specific emphasis in BRAF-mutated tumors. A total of 469 patients were included. Patients were stratified according to BRAF and HT status. Multivariate regression analysis was conducted to determine protective and risk factors of disease recurrence in patients with DTC. HT was associated with less-aggressive carcinomas including more frequent microcarcinomas (HT: 45.0% vs. no-HT: 34.0%, p = 0.02), less lymph node involvement (HT: 16.4% vs. no-HT: 26.1%, p = 0.02), and less disease recurrence (HT: 2.9% vs. no-HT: 11.9%, p = 0.002). BRAF mutation was also significantly associated with higher rates of lymph node involvement (BRAF-mutant: 41.9% vs. BRAF-wild type: 14.6%, p < 0.001) and almost two times the rate of recurrence (BRAF-mutant: 14.9% vs. BRAF-wild type: 6.5%, p = 0.004). Underlying HT was the only protective factor determined, reducing the odds of developing recurrence by 70% (HR: 0.30, 95%CI: 0.11-0.88). In the BRAF-wild type cohort, regression analysis continued to determine HT as a protective factor (p = 0.03). However, in the BRAF-mutant cohort, HT was no longer an independent protective factor (p = 0.20) against recurrence. Sub-group regression analysis, including PTC patients, similarly found HT as a protective factor only in BRAF-wild type patients (p = 0.039) and not BRAF-mutant (p = 0.627). The presence of underlying HT is associated with less aggressive tumors and is an independent protective factor against DTC recurrence, reducing the risk by 70%. HT remains a protective factor in BRAF-wild type carcinoma, but not in patients with BRAF-mutant carcinoma. HT may potentially be considered as a parameter which enhances American Thyroid Association patient risk stratification.

Successful treatment of breast metastasis from primary transverse colon cancer: A case report

The incidence of colon cancer is increasing worldwide. Treatments for colon cancer include surgery and surgery combined with chemotherapy and radiotherapy, but the median survival rate is still poor. Colon cancer most commonly metastasizes to the lymph nodes, lungs, liver, peritoneum, and brain, but breast metastasis is rare. There is no agreement on its treatment. A 23-year-old woman was admitted to our hospital for further treatment with a history of acute abdominal pain, nausea, and vomiting. Her physical examination and computed tomography scan revealed an abdominal tumor. Transverse colectomy was successfully performed. Histopathological examination revealed that the tumor was a mucosecretory adenocarcinoma with signet ring cells. The patient inadvertently found a mass in the outer upper quadrant of the right breast after four cycles of XELOX chemotherapy [oxaliplatin 130 mg/m2, d1, intravenous (iv) drip for 2 h; capecitabine 1000 mg/m2, po, bid, d1-d14]. After discussion with the patient, we performed a lumpectomy and frozen biopsy. The latter revealed that the breast tumor was intestinal metastasis. Genetic testing showed wild-type RAS and BRAF. So we replaced the original chemotherapy with FOLFIRI [irinotecan 180 mg/m2, d1, iv drip for 3-90 min; leucovorin 400 mg/m2, d1, iv drip for 2 h; 5-fluorouracil (5-FU) 400 mg/m2, d1 and 5-FU 1200 mg/(m2 d) × 2 d, continuous iv drip for 46-48 h] + cetuximab (500 mg/m2, d1, iv drip for 2 h). Serum levels of tumor markers returned to normal after several treatment cycles, and there was no evidence of tumor recurrence or metastasis. Breast metastasis from colon cancer is rare. Radical breast surgery should be avoided unless needed for palliation. Chemotherapy combined with targeted therapy should be the first choice.

Maintenance therapy with Fluoropyrimidine and cetuximab or bevacizumab after first line FOLFOX-chemotherapy in metastatic colorectal cancer according to RAS or BRAFV600E mutation status.

Fluoropyrimidine (FP) with oxaliplatin-based chemotherapy is the standard first-line treatment for metastatic colorectal cancer (mCRC); however, oxaliplatin-induced neuropathy critically affects the quality of life of patients. Maintenance strategies with FP plus bevacizumab have been well-established; nonetheless, the real-world outcomes of maintenance therapy with FP and cetuximab are unclear. We investigated the clinical outcomes of patients who underwent maintenance therapy with cetuximab. We retrospectively identified and analyzed patients with mCRC who were treated between 2012 and 2021 with first-line oxaliplatin-based induction chemotherapy (IC) plus biologic agents (either cetuximab or bevacizumab), and underwent maintenance therapy (IC regimen without oxaliplatin) after IC. In total, 19 patients who were treated with mFOLFOX6 (FP/leucovorin/oxaliplatin) with cetuximab, and 26 patients who were treated with mFOLFOX6 with bevacizumab were included. In the cetuximab group, all patients were KRAS-, NRAS-, and BRAF-wild type, whereas most patients in the bevacizumab group harbored KRAS or BRAFV600E or NRAS mutants. During the maintenance treatment, seven patients (four [21%] in the cetuximab group and three [11%] in the bevacizumab group) achieved partial response after achieving nadir during induction chemotherapy. The disease control rates of maintenance therapy were 79% and 74% in the cetuximab and bevacizumab groups, respectively. The median progression-free survival of maintenance therapy and overall survival was 5.98months and 32.4months in the cetuximab group, and 4.83months and 25.6months in the bevacizumab group, respectively. Maintenance therapy with FP plus biologic agents (either bevacizumab or cetuximab) is a feasible strategy for appropriate mCRC patients according to their RAS/BRAF status. Further large-scale randomized studies are needed to validate the efficacy of anti-epidermal growth factor receptor-based maintenance therapy.

TESC promotes differentiated thyroid cancer development by activating ERK and weakening NIS and radioiodine uptake.

Most differentiated thyroid cancer (DTC) patients have a good prognosis after surgery, but radioiodine refractory differentiated thyroid cancer (RAIR-DTC) patients have a significantly reduced 5-year survival rate (<60%) and a significantly increased recurrence rate (>30%). This study aimed to clarify the tescalcin (TESC) role in promoting the malignant PTC progression and providing a potential target for RAIR-DTC treatment. We analyzed TESC expression and clinicopathological characteristics using the Cancer Genome Atlas (TCGA) and performed qRT-PCR on tissue samples. TPC-1 and IHH-4 proliferation, migration, and invasion were detected after transfection with TESC-RNAi. Using Western blot (WB), several EMT-related indicators were detected. Moreover, iodine uptake of TPC-1 and IHH-4 after transfection with TESC-RNAi was detected. Finally, NIS, ERK1/2, and p-ERK1/2 levels were determined by WB. TESC was significantly upregulated in DTC tissues and positively correlated with BRAF V600E mutation based on data analysis from TCGA and our center. Reduced expression of TESC in both IHH-4 (BRAF V600E mutation) and TPC-1 (BRAF V600E wild type) cells significantly inhibited cell proliferation, migration, and invasion. It downregulated the EMT pathway markers Vimentin and N-cadherin, and increased E- cadherin. Moreover, TESC knockdown significantly inhibited ERK1/2 phosphorylation and decreased NIS expression in DTC cells, with a remarkably increased iodine uptake rate. TESC was highly expressed in DTC tissues and may have promoted metastasis through EMT and induced iodine resistance by downregulating NIS in DTC cells.

Abstract 5734: Designing RAF and MEK inhibitor combinations based on their biochemical properties to effectively target MAPK-driven cancers

Abstract Oncogenic alterations of the RAS/RAF/MEK/ERK signaling pathway drives growth of over 40% of human tumors, frequently due to activating mutations of components of the pathway, such as RAS or BRAF. Targeting the pathway using BRAF inhibitors (BRAFi) in combination with MEK inhibitors (MEKi) is now the standard of care for metastatic melanoma patients harboring the BRAF(V600E) mutation. However, effective targeted therapies are lacking for most cancers driven by other pathway alterations, including those with RAS activating mutations. The effectiveness of current clinical BRAFi relies on the fact that they bind selectively and inhibit the mutationally activated monomeric form of the BRAF(V600E) kinase in tumors but not wild-type BRAF in normal tissue where BRAF signals in its dimeric form. Yet, the development of adaptive resistance, frequently due to RAF dimerization, limits BRAFi therapeutic effectiveness. Another class of BRAFi equipotent for both monomeric and dimeric BRAF have been developed, but are predicted to have lower therapeutic index due to inhibition of dimeric wild-type BRAF in normal tissues as well. Recently, we identified and characterized a novel class of BRAFi that preferentially binds and inhibits dimeric BRAF over monomeric BRAF(V600E) (i.e. RAF dimer-selective inhibitors). Furthermore, we rationally designed a combinatorial approach utilizing a BRAF monomer-selective plus a BRAF dimer-selective inhibitor plus a MEK inhibitor, that potently disrupts the BRAF/MEK complex, to maximally inhibit BRAF(V600E) signaling in tumors while retaining a broad therapeutic index. This triple combination potently suppressed tumor growth of multiple BRAF(V600E) colorectal cancer and melanoma models resistant to the current clinical BRAFi and MEKi combinations both in vitro and in vivo. To design effective therapeutic approaches for RAS-mutated tumors, we also assessed the effectiveness of RAF and MEK inhibitors belonging to diverse biochemical and structural classes, either alone or in combination in RAS-mutant tumor models and normal cells with wild-type RAS signaling. We found that RAF dimer-selective inhibitors potently antagonized MAPK signaling and growth in various RAS mutant cancer models as compared to normal cells. We found further that RAF and MEK inhibitor combinations belonging to certain biochemical classes resulted in more potent MAPK suppression in RAS-mutant tumor as compared to wild-type RAS normal cells (“therapeutic synergy”) and should be prioritized for clinical testing. In contrast, those combinations which are more potent in normal over tumor cells (“adverse synergy”) are unlikely to be clinically successful. Thus, rationally designed combinations of selected RAFi and MEKi, based on their distinct biochemical properties, can uncover new therapeutic opportunities tailored for more effective targeting of BRAF or RAS mutant tumors. Citation Format: Ana Orive-Ramos, Christos Adamopoulos, Beau Baars, Jason Lam, Ankita Punetha, Jason Huang, Vasileios I. Petrou, Stuart A. Aaronson, Poulikos I. Poulikakos. Designing RAF and MEK inhibitor combinations based on their biochemical properties to effectively target MAPK-driven cancers. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5734.

Abstract 5348: Targeting MEK, alone and in combination with BRAF, in metastatic BRAFK601E-mutated melanoma

Abstract Mitogen-activated protein kinase/ERK signaling pathway has been one of the major mechanisms underlying melanoma haboring BRAF mutation. Of these, K601E mutation belongs to a rare mutation sub-type, comprising only 3% of the BRAF mutations in melanoma. Although patients with BRAF V600E/K mutation respond to MEK inhibitor, whether it also applies to those with BRAF K601E mutation remains elusive. Here, we examined the effects of MEK and BRAF/MEK inhibition on BRAFK601E-expressing melanoma cells. Melanoma cell line (MeWo) was transfected with doxycycline-inducible vector encoding wild-type or K601E-mutant BRAF. Subsequently, cells or xenograft-bearing mice were treated with trametinib, dabrafenib plus trametinib or sorafenib plus trametinib. Compared with BRAFWT, MTT assay demonstrated that BRAFK601E cells were more sensitive towards drug treatment. The effects of combined treatment were more profound. Tumorigenicity assay showed that trametinib treatment inhibited tumor growth of BRAFK601E xenografts. Our preliminary results demonstrated the therapeutic values of MEK and BRAF/MEK inhibitors against BRAFK601E-mutated melanoma. As previous studies report the superior therapeutic effects of BRAF/MEK inhibitors over MEK inhibitor alone, phenotype characterization of the cells, as well as underlying mechanisms behind such response, worth further investigation. Citation Format: Sze Man Chan, Sin Ting Chow, Sai Fung Yeung, Kwok Wing Stephen Tsui. Targeting MEK, alone and in combination with BRAF, in metastatic BRAFK601E-mutated melanoma. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5348.

Brain metastasis and survival outcomes after first-line therapy in metastatic melanoma: a multicenter DeCOG study on 1704 patients from the prospective skin cancer registry ADOREG

BackgroundDespite the availability of effective systemic therapies, a significant number of advanced melanoma patients develops brain metastases. This study investigated differences in incidence and time to diagnosis of brain metastasis...

Dichotomous Nitric Oxide-Dependent Post-Translational Modifications of STAT1 Are Associated with Ipilimumab Benefits in Melanoma.

Although Ipilimumab (anti-CTLA-4) is FDA-approved for stage III/IV melanoma adjuvant treatment, it is not used clinically in first-line therapy, given the superior relapse-free survival (RFS)/toxicity benefits of anti-PD-1 therapy. However, it is important to understand anti-CTLA-4's mechanistic contribution to combination anti-PD-1/CTLA-4 therapy and investigate anti-CTLA-4 therapy for BRAF-wild type melanoma cases reresected after previous adjuvant anti-PD-1 therapy. Our group published that nitric oxide (NO) increased within the immune effector cells among patients with longer RFS after adjuvant ipilimumab, whereas NO increased within the immune suppressor cells among patients with shorter RFS. Herein, we measured the post-translational modifications of STAT1 (nitration-nSTAT1 and phosphorylation-pSTAT1) that are important for regulating its activity via flow cytometry and mass spectrometry approaches. PBMCs were analyzed from 35 patients undergoing adjuvant ipilimumab treatment. Shorter RFS was associated with higher pSTAT1 levels before (p = 0.007) and after (p = 0.036) ipilimumab. Ipilimumab-treated patients with high nSTAT1 levels before and after therapy in PBMCs experienced decreased RFS, but the change in nSTAT1 levels before and after ipilimumab therapy was associated with longer RFS (p = 0.01). The measurement of post-translational modifications in STAT1 may distinguish patients with prolonged RFS from ipilimumab and provide mechanistic insight into responses to ipilimumab combination regimens.

The Driverless Triple-Wild-Type (BRAF, RAS, KIT) Cutaneous Melanoma: Whole Genome Sequencing Discoveries.

The genetic makeup of the triple-wild-type melanoma (BRAF, NRAS and NF1) has been known for some time, but those studies grouped together rare histopathological versions with common ones, as well as mucosal and even uveal ones. Here we used whole genome sequencing to genetically characterize the triple-wild-type melanoma (TWM), termed here as BRAF, RAS and KIT wild type (the most frequent oncogenic drivers of skin melanoma), using the most common histological forms and excluding rare ones. All these tumors except one were clearly induced by UV based on the mutational signature. The tumor mutational burden was low in TWM, except in the NF1 mutant forms, and a relatively high frequency of elevated LOH scores suggested frequent homologue recombination deficiency, but this was only confirmed by the mutation signature in one case. Furthermore, all these TWMs were microsatellite-stabile. In this driverless setting, we revealed rare oncogenic drivers known from melanoma or other cancer types and identified rare actionable tyrosine kinase mutations in NTRK1, RET and VEGFR1. Mutations of TWM identified genes involved in antitumor immunity (negative and positive predictors of immunotherapy), Ca++ and BMP signaling. The two regressed melanomas of this cohort shared a 17-gene mutation signature, containing genes involved in antitumor immunity and several cell surface receptors. Even with this comprehensive genomic approach, a few cases remained driverless, suggesting that unrecognized drivers are hiding among passenger mutations.