Intra-tumor heterogeneity of BRAF V600E mutation in lung adenocarcinomas

High Homogeneity of Mesothelin Expression in Primary and Metastatic Ovarian Cancer

To study the extent of heterogeneity of mesothelin overexpression in primary ovarian cancers and their peritoneal and lymph node metastases, a tissue microarray (TMA) was constructed from multiple sites of 220 ovarian cancers and analyzed by immunohistochemistry. One tissue core each was taken from up to 18 different tumor blocks per cancer, resulting in a total of 2460 tissue spots from 423 tumor sites (188 primary cancers, 162 peritoneal carcinosis, and 73 lymph node metastases). Positive mesothelin expression was found in 2041 of the 2342 (87%) arrayed tissue spots and in 372 of the 392 (95%) tumor sites that were interpretable for mesothelin immunohistochemistry. Intratumoral heterogeneity was found in 23% of 168 primary cancer sites interpretable for mesothelin and decreased to 12% in 154 peritoneal carcinosis and to 6% in 71 lymph node metastases ( P <0.0001). Heterogeneity between the primary tumor and matched peritoneal carcinosis was found in 16% of 102 cancers with interpretable mesothelin results. In these cancers, the mesothelin status switched from positive in the primary tumor to negative in the peritoneal carcinosis (3 cancers) in or vice versa (2 cancers), or a mixture of positive and negative peritoneal carcinoses was found (11 cancers). No such switch was seen between the mesothelin-interpretable primary tumors and their nodal metastases of 59 cancers, and only 1 mesothelin-positive tumor had a mixture of positive and negative lymph node metastases. In conclusion, mesothelin expression is frequent and highly homogeneous in ovarian cancer.

BRAF p.V600E status in epithelial areas of ameloblastoma with different histological aspects: Implications to the clinical practice

BACKGROUND

BRAF p.V600E is reported in up to 80% of ameloblastomas. Despite the high frequency, the presence of this mutation in different histopathological areas of the tumour has not been investigated. This information has an important role in the use of BRAF p.V600E assessment as an auxiliary tool in the differential diagnosis between unicystic ameloblastoma and other odontogenic cystic lesions, especially when only incisional biopsies are available. Therefore, the purpose of the present study was to investigate BRAF p.V600E heterogeneity in unicystic ameloblastoma.

METHODS

Five cases of ameloblastoma and two dentigerous cysts were analysed. The regions exhibiting different microscopic characteristics were selected from each ameloblastoma case and manually dissected. TaqMan allele-specific qPCR or Sanger sequencing was performed to determine BRAF p.V600E status.

RESULTS

We screened the mutation in a small cohort of UA and no molecular heterogeneity was found. Four cases of ameloblastoma (80%) exhibited BRAF p.V600E in all different areas evaluated. One case did not harbour the mutation in any microscopic region analysed. The BRAF mutation was absent in the dentigerous cysts.

CONCLUSION

Ameloblastomas appear to exhibit a homogeneous profile regarding the BRAF p.V600E no matter what histological feature is observed under light microscopy, suggesting that this molecular test may contribute to establish the correct diagnosis in cases microscopically resembling other odontogenic lesions.

Is time to progression associated with post-progression survival in previously treated metastatic non-small cell lung cancer with BRAF V600E mutation? A secondary analysis of phase II clinical trial data

OBJECTIVE

Longer time to progression (TTP) is associated with prolonged post-progression survival (PPS) in anaplastic lymphoma kinase+non-small cell lung cancer (NSCLC). This study evaluated whether TTP is associated with PPS among previously treated patients with metastatic v-Raf murine sarcoma viral oncogene homolog B V600E NSCLC receiving dabrafenib as monotherapy or in combination with trametinib.

DESIGN

Secondary analysis of phase II clinical trial data.

SETTING

Patients who experienced disease progression treated with dabrafenib monotherapy or in combination with trametinib as second line or later in an open-label, non-randomised, phase II study.

PRIMARY OUTCOME MEASURES

The primary outcome was the TTP-PPS association. PPS was assessed with Kaplan-Meier analysis among patients with shorter versus longer TTP (< or ≥6 months). The TTP-PPS association was quantified in the Cox models adjusting for clinical covariates.

RESULTS

Of the 84 included patients who progressed on dabrafenib monotherapy (n=57) or combination therapy (n=27), 60 (71%) died during post-progression follow-up. Patients with TTP ≥6 months experienced significantly longer PPS compared with those with TTP <6 months (median PPS: 9.5 vs 2.7 months, log-rank p<0.001). Each 3 months of longer TTP was associated with a 32% lower hazard of death following progression (HR 0.68, 95% CI 0.52 to 0.88) in the multivariable Cox model. Similar associations were seen in each treatment arm.

CONCLUSION

A longer TTP duration after treatment with dabrafenib monotherapy or combination therapy was associated with significantly longer PPS duration.

TRIAL REGISTRATION NUMBER

NCT01336634; Post-results.

Comparative Efficacy of Treatments for Previously Treated Advanced or Metastatic Non-Small-Cell Lung Cancer: A Network Meta-Analysis

INTRODUCTION

Due to the rarity of BRAF V600E mutation, no randomized study has compared the combination targeted therapy dabrafenib + trametinib with other second-line treatments for advanced or metastatic non-small-cell lung cancer (NSCLC). A network meta-analysis (NMA) was conducted to assess the comparative efficacy of treatments among patients with previously treated advanced or metastatic NSCLC.

METHODS

Randomized trials of dabrafenib + trametinib, docetaxel, erlotinib, nintedanib + docetaxel, nivolumab, pemetrexed, pembrolizumab, and best supportive care as second-line or above treatments for advanced or metastatic NSCLC identified in a systematic literature review were included in the NMA. Overall response rates (ORRs) and disease control rates (DCRs) were compared using logit models; progression-free survival (PFS) and overall survival (OS) were compared using fractional polynomial hazards models. Dabrafenib + trametinib was linked into the evidence network through a matching-adjusted indirect comparison versus nivolumab.

RESULTS

Ten trials met the inclusion criteria and were included in the NMA. Dabrafenib + trametinib, pembrolizumab, and nivolumab were associated with the highest odds of achieving overall response (12.2, 1.2, and 0.7 times higher, respectively, compared with docetaxel). Estimated DCR was higher for dabrafenib + trametinib, nintedanib + docetaxel, and pemetrexed compared with other treatments. Patients treated with dabrafenib + trametinib, nivolumab, and pembrolizumab had the lowest hazards of disease progression or death during follow-up (72, 61, and 29% lower hazard of progression at 6 months; 61, 48, and 46% lower hazard of death at 1 year, respectively, compared with docetaxel).

CONCLUSION

Dabrafenib + trametinib, pembrolizumab, and nivolumab were associated with higher ORR and prolonged PFS and OS compared with chemotherapy in previously treated advanced or metastatic NSCLC.

FUNDING

Novartis Pharmaceuticals Corporation.

Intra-tumor heterogeneity of cancer cells and its implications for cancer treatment

Recent studies have revealed extensive genetic and non-genetic variation across different geographical regions of a tumor or throughout different stages of tumor progression, which is referred to as intra-tumor heterogeneity. Several causes contribute to this phenomenon, including genomic instability, epigenetic alteration, plastic gene expression, signal transduction, and microenvironmental differences. These variables may affect key signaling pathways that regulate cancer cell growth, drive phenotypic diversity, and pose challenges to cancer treatment. Understanding the mechanisms underlying this heterogeneity will support the development of effective therapeutic strategies.