The survival outcomes of the FLAURA trial support osimertinib as the new standard of care for untreated patients harboring activating mutations in the epidermal growth factor receptor (EGFR). Despite the initial response, disease progression invariably occurs. Although uncommon, BRAF V600E mutation arises as a unique mechanism of resistance, and thus far, no prospective studies are available to support concurrent EGFR/BRAF blockade. We report a case of impressive radiological and ctDNA response under dabrafenib, trametinib, and osimertinib in an advanced EGFR-mutant lung adenocarcinoma patient who developed BRAF V600E as one of the acquired resistance mechanisms to second-line osimertinib. Moreover, the patient experienced remarkable clinical improvement and good tolerance to combination therapy. The present case suggests the importance of prospective studies evaluating both efficacy and safety of the combination in later line settings and points towards the potential of ctDNA to monitor resistance mechanisms and treatment benefit in clinical practice.

Introduction Chordomas are rare malignancies of bone origin that occur in the axial skeleton, typically the skull base and lumbar/sacral regions. Although often classified as low-grade neoplasms, its locally infiltrative behavior may result in significant morbidity and mortality. Optimal surgical resection may be curative, but up to 50% of the cases relapse within 5 years, and currently there are no systemic treatments approved in this setting. A large proportion of these tumors express stem-cell factor receptor (c-KIT) and platelet-derived growth factor receptors (PDGFRs), providing a rationale for the use of tyrosine-kinase inhibitors (TKIs). Case report A 27-year-old male presented with recurrent chordoma of the lumbar spine 4 years after initial diagnosis. Salvage therapies in the interval included repeat resections and radiation therapy. He ultimately developed multifocal recurrence not amenable to complete excision or reirradiation. A comprehensive genomic profiling assay was performed and revealed nondrugable alterations. Decision was made to proceed with systemic treatment with pazopanib 800 mg/day, resulting in tumor reduction (−23.1% reduction in size) and prolonged disease control. Conclusion For this patient with a multiple recurrent chordoma and limited treatment options, pazopanib resulted in sustained clinical benefit following initial tumor reduction.

Objectives: to report outcomes of four cases of chemo-refractory RET-rearranged non-small cell lung carcinomas (NSCLCs) treated with alectinib in a single center. Materials and methods: we retrospectively assessed and reported the activity and tolerability of alectinib 600 mg twice daily in advanced and chemo-refractory RET-rearranged NSCLC patients treated in a Brazilian institution. Identification of RET rearrangements was performed using the FoundationOne® next-generation sequencing (NGS) platform. Results: The four patients herein reported were white, female and non-smokers, ranging between 59-66 years of age. All patients had been previously treated with chemotherapy and were TKI naïve; three of them presented disease progression to nivolumab as well. Molecular tumor profiling showed a KIF5B-RET fusion in three patients and a CCDC6-RET in the fourth. One patient exhibited disease progression and clinical deterioration two months after treatment initiation. Disease control was documented in two patients with PFS ranging from 4 to 5 months (one partial metabolic response and one stable disease). In one of the cases, which developed oligoprogression on alectinib, radiation therapy plus post-progression alectinib were able to provide additional disease control for 9 more months. No grade 3/4 adverse events, dose reductions or discontinuation due to toxicity were documented. Conclusion: Although this is a small single center evaluation, alectinib was well tolerated and demonstrated clinical activity against advanced RET-rearranged NSCLCs, suggesting its potential role in this specific subset of malignancies. Clinical trials addressing its efficacy and the optimal dosing schedule in the present context are underway, and results are eagerly awaited.

Background Takotsubo syndrome (TTS), also known as stress cardiomyopathy, apical ballooning syndrome and broken heart syndrome, is characterized by acute-onset chest pain, electrocardiographic (ECG) abnormalities and reversible left ventricular (LV) disfunction in the absence of a culprit obstructive lesion in the coronary arteries; therefore, myocardial infarction is the most important differential diagnosis. Usually induced by emotional/physical stress, its treatment consists in hemodynamic support until complete and spontaneous recovery occurs, which is generally achieved within a few days to weeks. Cervical malignancies are an important public health issue in low/middle-income countries and, in the setting of locally advanced disease, concurrent chemoradiation followed by brachytherapy is considered the standard treatment, harboring curative potential. Case report We report a case of a 38-year-old woman who underwent concurrent chemoradiotherapy and developed cardiopulmonary arrest in ventricular fibrillation during a brachytherapy session. Complementary tests disclosed altered ECG and cardiac biomarkers, no evidence of coronary artery obstruction, as well as LV disfunction consistent with TTS on echocardiogram and cardiac MRI. After few days of supportive therapy, complete recovery of heart function was observed. Conclusions Especially for cancer patients, who usually experience intense emotional/physical stress intrinsically associated with their diagnosis and aggressive treatments, considering TTS as a differential diagnosis is warranted. Intracavitary brachytherapy procedure may represent a trigger for TTS.

The clinical significance of gene fusions detected by DNA-based next generation sequencing remains unclear as resistance mechanisms to EGFR tyrosine kinase inhibitors in EGFR mutant non-small cell lung cancer. By studying EGFR inhibitor-resistant patients treated with a combination of an EGFR inhibitor and a drug targeting the putative resistance-causing fusion oncogene, we identify patients who benefit and those who do not from this treatment approach. Through evaluation including RNA-seq of potential drug resistance-imparting fusion oncogenes in 504 patients with EGFR mutant lung cancer, we identify only a minority of them as functional, potentially capable of imparting EGFR inhibitor resistance. We further functionally validate fusion oncogenes in vitro using CRISPR-based editing of EGFR mutant cell lines and use these models to identify known and unknown drug resistance mechanisms to combination therapies. Collectively, our results partially reveal the complex nature of fusion oncogenes as potential drug resistance mechanisms and highlight approaches that can be undertaken to determine their functional significance.

PURPOSE Li-Fraumeni syndrome (LFS) is rare in the worldwide population, but it is highly prevalent in the Brazilian population because of a founder mutation, TP53 p.R337H, accounting for 0.3% of south and southeastern population. Clinical criteria for LFS may not identify all individuals at risk of carrying the Brazilian founder mutation because of its lower penetrance and variable expressivity. This variant is rarely described in databases of somatic mutations. Somatic findings in tumor molecular profiling may give insight to identify individuals who might be carriers of LFS and allow the adoption of risk reduction strategies for cancer. MATERIALS AND METHODS We determined the frequency of the TP53 p.R337H variant in tumor genomic profiling from 755 consecutive Brazilian patients with pan-cancer. This is a retrospective cohort from January 2013 to March 2020 at a tertiary care center in Brazil. RESULTS The TP53 p.R337H variant was found in 2% (15 of 755) of the samples. The mutation allele frequency ranged from 30% to 91.7%. A total of seven patients were referred for genetic counseling and germline testing after tumor genomic profiling results were disclosed. All the patients who proceeded with germline testing (6 of 6) confirmed the diagnosis of LFS. Family history was available in 12 cases. Nine patients (9 of 12) did not meet LFS clinical criteria. CONCLUSION The identification of the TP53 p.R337H variant in tumor genomic profiling should be a predictive finding of LFS in the Brazilian population and should prompt testing for germline status confirmation.

Epidermal growth factor receptor antibodies (EGFR-Abs) confer a survival benefit in patients with RAS wild-type metastatic colorectal cancer (mCRC), but resistance invariably occurs. Previous data showed that only a minority of cancer cells harboured known genetic resistance drivers when clinical resistance to single-agent EGFR-Abs had evolved, supporting the activity of non-genetic resistance mechanisms. Here, we used error-corrected ctDNA-sequencing (ctDNA-Seq) of 40 cancer genes to identify drivers of resistance and whether a genetic resistance-gap (a lack of detectable genetic resistance mechanisms in a large fraction of the cancer cell population) also occurs in RAS wild-type mCRCs treated with a combination of EGFR-Abs and chemotherapy. We detected one MAP2K1/MEK1 mutation and one ERBB2 amplification in 2/3 patients with primary resistance and KRAS, NRAS, MAP2K1/MEK1 mutations and ERBB2 aberrations in 6/7 patients with acquired resistance. In vitro testing identified MAP2K1/MEK1 P124S as a novel driver of EGFR-Ab resistance. Mutation subclonality analyses confirmed a genetic resistance-gap in mCRCs treated with EGFR-Abs and chemotherapy, with only 13.42% of cancer cells harboring identifiable resistance drivers. Our results support the utility of ctDNA-Seq to guide treatment allocation for patients with resistance and the importance of investigating further non-canonical EGFR-Ab resistance mechanisms, such as microenvironmentally-mediated resistance. The detection of MAP2K1 mutations could inform trials of MEK-inhibitors in these tumours.

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