BRAF K601

The detection of BRAF fusions and their many partners was enabled by the Afirma XA exome-enriched RNASeq panel. Although BRAF fusions occurred in only 0.2% of thyroid nodules, they were GSC-Suspicious and lacked typical BRAF/RAS mutations. Interestingly, expression signatures associated with malignancy varied by fusion partner.

Since 2016, patients with BRAFK601E-positive nodules receive less aggressive treatment. The risk of recurrence of BRAFK601E-positive tumors without other, high-risk features appears to be low, and lobectomy without radioiodine is likely sufficient treatment for these patients.

K601E-mutated neoplasms could be a unique clinicopathological entity associated with low-risk histology and reduced extrathyroidal extension, consistent with a more indolent course than V600E mutants. Although detecting K601E may potentially guide conservative management, further prospective studies are needed.

P2, N=26, Active, not recruiting, University Health Network, Toronto | Trial completion date: Mar 2024 --> Dec 2024 | Trial primary completion date: Mar 2024 --> Dec 2024

Nine patients received targeted therapy; dabrafenib/trametinib (6), pembrolizumab (2), and entrectinib (1), mostly upon tumor progression (7). Outsourcing of NGS testing was feasible; however, criteria for case selection are needed. In addition, local capacity-building in conducting the test, interpretation of the results, and access to "new drugs" continue to be a challenge in LMICs.

The BRAF mutation may represent important genetic alteration in a subset of IDC-P, highlighting the role of MAPK signaling pathway in this subtype of PCa. To the best of knowledge, this is the first description of non-V600 BRAF mutation in setting of IDC-P, which may in part explain the aggressive phenotype seen in IDC-P and could also bring more treatment options for PCa patients with IDC-P harboring such mutations.

To overcome these challenges, we conjugated a STAT3-specific decoy to thalidomide, a ligand to cereblon in E3 ubiquitin ligase complex, to generate a proteolysis-targeting chimera (STAT3DPROTAC)...Finally, local C-STAT3DPROTAC administration to human Ly3 lymphoma-bearing mice triggered tumor regression, while control C-STAT3D and C-SCR treatments had limited effects. Our results underscore the feasibility of using a PROTAC strategy for cell-selective, decoy oligonucleotide-based STAT3 targeting of and potentially other tumorigenic transcription factors for cancer therapy.

Cobimetinib plus vemurafenib showed antitumor activity in patients with advanced solid tumors with BRAF V600E mutations; additional study is warranted to confirm the antitumor activity in tumors with non-V600E BRAF mutations.

Genetic mutations were not significantly associated with clinical outcomes. However, NRAS mutations may be a prognostic predictor and CTNNB1 mutation may be a treatment effector for immune check inhibitors. A larger prospective study is required to clarify the clinical importance of genetic mutations in patients with SNMM.

Eight patients received targeted therapy; Dabrafenib/Trametinib (5), Pembrolizumab (2), Entrectinib (1), while radio-chemotherapy was used in the others. Sent abroad NGS testing was feasible, however local capacity building is necessary. In this highly selected tumor cohort, high percentage of targetable alterations were identified. NGS was helpful to characterize tumors more and to offer alternative therapies.

P2, N=26, Active, not recruiting, University Health Network, Toronto | Trial completion date: Dec 2023 --> Mar 2024 | Trial primary completion date: Dec 2023 --> Mar 2024 | Recruiting --> Active, not recruiting

Patients with NSCLCs with BRAF non-V600E, especially class III, were associated with poorer therapeutic outcomes than those with V600E. Furthermore, patients with NSCLC with class IIa had distinct clinicogenomic features, and further preclinical and clinical studies are needed to evaluate class IIa mutations as a therapeutic target.

In recent years, the mutational landscape of thyroid tumors has been extensively described, and two molecular profiles have been identified: RAS-like (NRAS, HRAS, and KRAS mutations; EIF1AX mutations; BRAF K601E mutation; and PPARG and THADA fusions) and BRAF-like (including BRAF mutation and RET and BRAF fusions). The purpose of this review is to discuss the latest molecular findings in the context of indeterminate thyroid nodules, highlighting the role of molecular tests in patients' management.

We found an association of K601E mutants with follicular variants of thyroid cancer such as FV‐PTC, FA, and FTC. Our findings may also be consistent with K601E mutants having a more indolent course, but more data is needed to show significance and make clinical recommendations.

Furthermore, TP53, LRP1B, STK11, SPTA1and MAGI2 were significantly over-mutated in Class II and III (p<0.06) and SETD2 is over-mutated in Class I (p<0.001), might suggesting relatively poor prognosis in NSCLC patients. Conclusions The characteristics of Chinese NSCLC were further explored, including BRAF mutation types, the incidence of related co-mutations and TMB value, which is helpful to formulate targeted therapy strategies to adapt to different types of BRAF mutation functions according to their genomic and clinical characteristics.

However, the MRI acquired four weeks after adding capmatinib showed partial response (PR) of LM.Patients with ALK+ NSCLC switched from alectinib [n=2] or brigatinib [n=1] to lorlatinib following LP. Although we identified the primary driver in 26 out of 28 patients with EGFRm+ NSCLC, only seven CSF samples showed RM (ERBB2, EGFR and PIK3CA). Commonly identified RMs in systemic progression such as EGFR C797X and METamp were not identified in CSF or plasma. Identifying resistance mechanisms to targeted therapy in LM proves difficult.

Activating BRAF alterations were detected in ~3% of prostate cancers, and most were Class II mutations and rearrangements; BRAF V600 mutations were exceedingly rare. These findings suggest that BRAF activation in prostate cancer is unique from other cancers and supports further clinical investigation of therapeutics targeting the MAPK pathway.

RAS mutations were associated with the follicular variant, encapsulated tumor, and no extrathyroidal extension. HRAS-mutated PTC frequently exhibited tumor multifocality.

In this large cohort of consecutive DTC patients with prospective 7-gene molecular testing and long-term follow-up, 5- and 10-year DFS was higher in patients with RAS-like TC compared to those with BRAF-like TC. ~60% of recurrences occurred in the first 2 years, while most recurrences >5 years were locoregional or biochemical and only one patient developed distant metastatic disease. Further analysis with additional comprehensive genetic variables is ongoing to better identify patients who are at risk for long-term recurrence.*Unless otherwise noted, all abstracts presented at ENDO must not be released to the press or the public until the date and time of presentation.

The study highlights the heterogeneity of patients with BRAF class II and class III regarding histology and co-mutational status, with both classes equally frequent. A more granular investigation of non-V600X alterations and their associated clinical outcomes under different treatment approaches is ongoing.

P2 | "According to liquid biopsy before second- and third-line therapies, treatment sequences are: FOLFIRI + cetuximab (first-line), FOLFOX + cetuximab (second-line); irinotecan + cetuximab (third-line) in patients with plasma ctDNA RAS/BRAFV600E WT tumors. In patients with RAS/BRAFV600E mutant tumors, second-line is FOLFOX + bevacizumab, while third-line is regorafenib or trifluridine/tipiracil (investigator's choice)... Both tumor tissue- and liquid biopsy-based comprehensive genomic profiling by NGS identify additional molecular alterations, that could be involved in resistance to anti-EGFR monoclonal antibodies, as compared to PCR-based tumor tissue analysis. CAPRI 2-GOIM trial will determine if NGS would allow better selection of RAS/BRAFV600E WT mCRC patients for the most appropriate treatments through three sequential lines of therapies."

Thalidomide molecule (Tha), a ligand for cereblon (CRBN) within a E3 ubiquitin ligase complex, was tethered to the 3’ end of S3dODN...The inhibitory effect of C-S3dODNPROTAC was specific to STAT3 and it did not affect levels of the related STAT5 and STAT1 proteins. To our knowledge, this is the first demonstration that the PROTAC approach can be successfully applied to decoy-based targeting of undruggable transcription factors such as STAT3.

A complex of methods for determination of the nucleotide sequence of the BRAF codons 592-601 and the algorithm for testing samples and analyzing mutations in the BRAF codons 600-601 was developed. The method provides sufficient sensitivity to detect frequent mutations in codons 600 and 601 and allows them to be precisely differentiated.

Clofarabine and cladribine are two FDA approved drugs that are administered for their inhibitory acts on DNA synthesis to treat relapsed or refractory acute lymphoblastic and myeloid leukemia. Among 26 new derivatives, we identified two compounds, BK50164 and BK60106, that cause cell death specifically in ES primarily due to inhibition of CD99 but not via inhibition of DNA synthesis. These findings provide a road map for the future development selective CD99 inhibitors for targeted treatment of ES.

Subsequently, cells or xenograft-bearing mice were treated with trametinib, dabrafenib plus trametinib or sorafenib plus trametinib. 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.

The findings of this cohort study suggest that there are broad differences among organoids with different BRAF variant subtypes in sensitivity to BRAF or MEK inhibitors. Identifying and classifying BRAF variants may be able to help guide precise treatment for patients with ICC.

Indeed, we show that BRAF non-V600E mutations can be found in tumors with metastatic potential. However, in both aggressive cases, the BRAF mutations were concomitant with other molecular alterations, such as TERT promoter mutation.

P1/2, N=17, Active, not recruiting, Memorial Sloan Kettering Cancer Center | Trial completion date: Feb 2023 --> Feb 2024 | Trial primary completion date: Feb 2023 --> Feb 2024

This study presents the first large-scale genomic characterization of BRAF mutations in patients with prostate cancer using both tissue and ctDNA NGS analysis. Among thousands of samples from prostate cancer patients, K601E was the most common BRAF mutation. This confirms findings of smaller studies and has implications for developmental therapeutics.

Activating BRAF alterations are detected in ~3% of aPC, with frequent BRAF-SND1 fusions. BRAF RE represent almost half of aPC BRAF GA, the highest fraction observed across a pan-tumor dataset. In addition, we detected a higher incidence of concurrent CDK12 GA and a lower relative frequency of concurrent PTEN,APC, and TMPRSS2-ERG GA.

XA improved risk stratification and identification of malignant thyroid disease with a very high ROM in GSC “suspicious” nodules. Although a negative XA result was associated with lower RoM in our cohort, a negative XA result should not be used as a “rule-out” test.

The combination of dabrafenib plus trametinib was recently FDA-approved for use in these BRAF V600E altered unresectable or metastatic cancers. Analysis of whole-exome and whole transcriptome sequencing data found actionable BRAF mutations in 4.4% of GI cancer patients, 37.6% of whom had BRAF mutations not at V600. Several biomarkers were significantly associated with BRAF alterations. Assays that are limited to DNA sequencing, or to targeted gene panels, may not detect mutations and fusions that could aid in therapy selection and prognosis.

P1/2, N=17, Active, not recruiting, Memorial Sloan Kettering Cancer Center | Recruiting --> Active, not recruiting | N=38 --> 17

The combination of C + V has antitumor activity in heavily pretreated patients with CRC with BRAF mutations.

Rare BRAF mutations are not anecdotal in the metastatic melanoma population. Although data interpretation must remain careful owing to the limited size of some subsets of patients, non-E/K V600 BRAF mutations seem to confer a high sensitivity to targeted therapy, whereas MAPKis seem less effective in patients with non-V600 BRAF mutations. However, this strategy may be used as an alternative option in the case of immunotherapy failure in the latter population.

Four patients received combined BRAF/MEK inhibitors, two patients BRAF inhibitor monotherapy, and six patients were treated with ICI for advanced melanoma; four patients received adjuvant treatment with nivolumab. Given the few cases and the absence of randomized clinical trials, it is important to report clinical experiences, which can guide physicians in the treatment of melanomas harboring rare BRAF mutations.

Most nodules had RAS-like mutations and most were benign or low-risk neoplasms (NIFTP). This study supports the role of histologic examination in the distinction of malignancy in RAS-like thyroid neoplasms and underscores the role of molecular testing in risk stratification, patient counseling, and operative management.

The combination of a genetic analysis and computational simulation model may help predict the sensitivity for dabrafenib in cases with a rare BRAF compound mutation. The construction of a genomic and simulation fused database is important for the development of personalized medicine in this field.

PDOs were not sensitive to Vemurafenib and Cobimetinib given alone and sensitive to their combination, although not as responsive as BRAF PDOs. Tumor analysis showed that BRAF displayed both increased phosphorylation of Erk1/2 at cytoplasmic level and activation of Notch resistance signaling. This prompted us to inhibit Notch signaling with Nirogacestat, achieving a greater antitumor response and providing PDOs-based evaluation of treatment efficacy in such rare metastatic melanoma.

In this large cohort of patients with NIFTP diagnosed at the time of surgery and managed typically by lobectomy with no radioiodine ablation, no evidence of tumor recurrence was identified on a limited follow-up. This finding supports indolent clinical course of NIFTP.