Cutaneous squamous-cell carcinomas and keratoacanthomas are common findings in patients treated with BRAF inhibitors.
We performed a molecular analysis to identify oncogenic mutations (HRAS, KRAS, ...NRAS, CDKN2A, and TP53) in the lesions from patients treated with the BRAF inhibitor vemurafenib. An analysis of an independent validation set and functional studies with BRAF inhibitors in the presence of the prevalent RAS mutation was also performed.
Among 21 tumor samples, 13 had RAS mutations (12 in HRAS). In a validation set of 14 samples, 8 had RAS mutations (4 in HRAS). Thus, 60% (21 of 35) of the specimens harbored RAS mutations, the most prevalent being HRAS Q61L. Increased proliferation of HRAS Q61L-mutant cell lines exposed to vemurafenib was associated with mitogen-activated protein kinase (MAPK)-pathway signaling and activation of ERK-mediated transcription. In a mouse model of HRAS Q61L-mediated skin carcinogenesis, the vemurafenib analogue PLX4720 was not an initiator or a promoter of carcinogenesis but accelerated growth of the lesions harboring HRAS mutations, and this growth was blocked by concomitant treatment with a MEK inhibitor.
Mutations in RAS, particularly HRAS, are frequent in cutaneous squamous-cell carcinomas and keratoacanthomas that develop in patients treated with vemurafenib. The molecular mechanism is consistent with the paradoxical activation of MAPK signaling and leads to accelerated growth of these lesions. (Funded by Hoffmann-La Roche and others; ClinicalTrials.gov numbers, NCT00405587, NCT00949702, NCT01001299, and NCT01006980.).
PURPOSE To assess pharmacodynamic effects and intrinsic and acquired resistance mechanisms of the BRAF inhibitor vemurafenib in BRAF(V600)-mutant melanoma, leading to an understanding of the ...mechanism of action of vemurafenib and ultimately to optimization of metastatic melanoma therapy. METHODS In the phase II clinical study NP22657 (BRIM-2), patients received oral doses of vemurafenib (960 mg twice per day). Serial biopsies were collected to study changes in mitogen-activated protein kinase (MAPK) signaling, cell-cycle progression, and factors causing intrinsic or acquired resistance by immunohistochemistry, DNA sequencing, or somatic mutation profiling. Results Vemurafenib inhibited MAPK signaling and cell-cycle progression. An association between the decrease in extracellular signal-related kinase (ERK) phosphorylation and objective response was observed in paired biopsies (n = 22; P = .013). Low expression of phosphatase and tensin homolog showed a modest association with lower response. Baseline mutations in MEK1(P124) coexisting with BRAF(V600) were noted in seven of 92 samples; their presence did not preclude objective tumor responses. Acquired resistance to vemurafenib associated with reactivation of MAPK signaling as observed by elevated ERK1/2 phosphorylation levels in progressive lesions and the appearance of secondary NRAS(Q61) mutations or MEK1(Q56P) or MEK1(E203K) mutations. These two activating MEK1 mutations had not previously been observed in vivo in biopsies of progressive melanoma tumors. CONCLUSION Vemurafenib inhibits tumor proliferation and oncogenic BRAF signaling through the MAPK pathway. Acquired resistance results primarily from MAPK reactivation driven by the appearance of secondary mutations in NRAS and MEK1 in subsets of patients. The data suggest that inhibition downstream of BRAF should help to overcome acquired resistance.
Heterogeneity in the underlying mechanisms of disease processes and inter-patient variability in drug responses are major challenges in drug development. To address these challenges, biomarker ...strategies based on a range of platforms, such as microarray gene-expression technologies, are increasingly being applied to elucidate these sources of variability and thereby potentially increase drug development success rates. With the aim of enhancing understanding of the regulatory significance of such biomarker data by regulators and sponsors, the US Food and Drug Administration initiated a programme in 2004 to allow sponsors to submit exploratory genomic data voluntarily, without immediate regulatory impact. In this article, a selection of case studies from the first 5 years of this programme - which is now known as the voluntary exploratory data submission programme, and also involves collaboration with the European Medicines Agency - are discussed, and general lessons are highlighted.
The Eastern woodchuck (
) has been extensively used in research of chronic hepatitis B and liver cancer because its infection with the woodchuck hepatitis virus closely resembles a human hepatitis B ...virus infection. Development of novel immunotherapeutic approaches requires genetic information on immune pathway genes in this animal model. The woodchuck genome was assembled with a combination of high-coverage whole-genome shotgun sequencing of Illumina paired-end, mate-pair libraries and fosmid pool sequencing. The result is a 2.63 Gigabase (Gb) assembly with a contig N50 of 74.5 kilobases (kb), scaffold N50 of 892 kb, and genome completeness of 99.2%. RNA sequencing (RNA-seq) from seven different tissues aided in the annotation of 30,873 protein-coding genes, which in turn encode 41,826 unique protein products. More than 90% of the genes have been functionally annotated, with 82% of them containing open reading frames. This genome sequence and its annotation will enable further research in chronic hepatitis B and hepatocellular carcinoma and contribute to the understanding of immunological responses in the woodchuck.
Polymorphisms of activating Fc-γ receptors (FCGRs) on natural killer cells and macrophages result in variable affinity for immunoglobulin G1 monoclonal antibodies and subsequently modulate ...antibody-dependent cellular cytotoxicity (ADCC) activity. Whether single-nucleotide polymorphisms of FCGRs correlate with survival of chronic lymphocytic leukemia (CLL) patients treated with a monoclonal antibody containing regimen is unclear. We assessed the FCGR3A and FCGR2A genotype of patients enrolled in the REACH trial, where patients received fludarabine and cyclophosphamide (FC) or rituximab plus FC (R-FC). FCGR3A and FCGR2A polymorphisms did not demonstrate prognostic significance in the FC arm (P = .42 and P = .64, respectively) or R-FC arm (P = .41 and P = .88, respectively) with respect to progression free survival. Patients with intermediate affinity genotypes (FV and HR) benefited significantly from addition of rituximab (hazard ratio = 0.55 0.37-0.8 CI; P = .0017 and hazard ratio = 0.63 0.44-0.9 CI; P = .011, respectively). Similar benefit was suggested for patients with high- affinity VV and HH (hazard ratio = 0.86 0.4-1.84 CI; P = .7 and hazard ratio = 0.7 0.41-1.18 CI; P = .18, respectively) and low-affinity FF and RR (hazard ratio = 0.85 0.56-1.29 CI; P = .44 and hazard ratio = 0.82 0.47-1.42 CI; P = .48, respectively). Overall, our results suggest that FCGR2A and FCGR3A polymorphisms do not significantly influence the outcomes of relapsed or refractory CLL patients treated with FC or the monoclonal antibody regimen R-FC.
The expression of cyclooxygenase‐2 (COX‐2) and the synthesis of prostaglandin E2 (PGE2) as well as of cytokines such as interleukin‐6 (IL‐6) have all been suggested to propagate neuropathology in ...different brain disorders such as HIV‐dementia, prion diseases, stroke and Alzheimer's disease. In this report, we show that PGE2‐stimulated IL‐6 release in U373 MG human astroglioma cells and primary rat astrocytes. PGE2‐induced intracellular cAMP formation was mediated via prostaglandin E receptor 2 (EP2), but inhibition of cAMP formation and protein kinase A or blockade of EP1/EP2 receptors did not affect PGE2‐induced IL‐6 synthesis. This indicates that the cAMP pathway is not part of PGE2‐induced signal transduction cascade leading to IL‐6 release. The EP3/EP1‐receptor agonist sulprostone failed to induce IL‐6 release, suggesting an involvement of EP4‐like receptors. PGE2‐activated p38 mitogen‐activated kinase (p38 MAPK) and protein kinase C (PKC). PGE2‐induced IL‐6 synthesis was inhibited by specific inhibitors of p38 MAPK (SB202190) and PKC (GF203190X). Although, up to now, EP receptors have only rarely been linked to p38 MAPK or PKC activation, these results suggest that PGE2 induces IL‐6 via an EP4‐like receptor by the activation of PKC and p38 MAPK via an EP4‐like receptor independently of cAMP.
Exon 19 deletions and the exon 21 L858R mutation of the epidermal growth factor receptor gene (EGFR) predict activity of EGFR tyrosine kinase inhibitors, including erlotinib; however, the ability of ...less common EGFR mutations to predict efficacy of erlotinib is unclear.
The efficacy of erlotinib in individual patients with rare EGFR mutations from the MERIT, SATURN, TITAN, TRUST, ATLAS, BeTa, and FASTACT-2 trials was analyzed and compared with data from the literature.
In the patients tested for biomarkers, the frequency of rare mutations identified here ranged from 1.7% (eight of 467) in the SATURN study to 7.4% (27 of 364) in ATLAS. Some rare mutations were associated with greater clinical benefit from EGFR tyrosine kinase inhibitor therapy or improved prognosis independent of treatment, whereas others appeared to have a poorer prognosis. In particular, exon 18 G719 mutations, exon 19 K757R and E746G mutations, the exon 20 S768I mutation, and the exon 21 G836S mutation appeared to confer a good outcome with erlotinib treatment, whereas exon 18 S720I showed a particularly poor outcome. Owing to the small number of patients with each mutation, however, it is difficult to confirm whether these rare mutations do indeed confer sensitivity or resistance to erlotinib.
Erlotinib can have different efficacy depending on the specific EGFR mutation. More research is needed to create a central database such as the My Cancer Genome database of rare mutations to definitively confirm whether these mutations are activating, resistant, or neutral.
Circulating tumor DNA (ctDNA) is a new circulating tumor biomarker which might be used as a prognostic biomarker in a way similar to circulating tumor cells (CTCs). Here, we used the high prevalence ...of TP53 mutations in triple negative breast cancer (TNBC) to compare ctDNA and CTC detection rates and prognostic value in metastatic TNBC patients. Forty patients were enrolled before starting a new line of treatment. TP53 mutations were characterized in archived tumor tissues and in plasma DNA using two next generation sequencing (NGS) platforms in parallel. Archived tumor tissue was sequenced successfully for 31/40 patients. TP53 mutations were found in 26/31 (84%) of tumor samples. The same mutation was detected in the matched plasma of 21/26 (81%) patients with an additional mutation found only in the plasma for one patient. Mutated allele fractions ranged from 2 to 70% (median 5%). The observed correlation between the two NGS approaches (R2 = 0.903) suggested that ctDNA levels data were quantitative. Among the 27 patients with TP53 mutations, CTC count was ≥1 in 19 patients (70%) and ≥5 in 14 patients (52%). ctDNA levels had no prognostic impact on time to progression (TTP) or overall survival (OS), whereas CTC numbers were correlated with OS (p = 0.04) and marginally with TTP (p = 0.06). Performance status and elevated LDH also had significant prognostic impact. Here, absence of prognostic impact of baseline ctDNA level suggests that mechanisms of ctDNA release in metastatic TNBC may involve, beyond tumor burden, biological features that do not dramatically affect patient outcome.
What's New?
Circulating tumor DNA (ctDNA) has shown promise as a prognostic biomarker. In this study, the authors compared detection rates and prognostic value of ctDNA versus circulating tumor cells (CTCs) in the plasma of metastatic triple‐negative breast cancer (TNBC) patients. The ctDNA was detected more frequently than CTCs. However, while CTC numbers were correlated with prognosis, baseline ctDNA levels were not. This suggests that ctDNA might be more useful in identifying mutations that could provide therapeutic targets than as a prognostic biomarker.
Background.
Vemurafenib has been approved for the treatment of patients with advanced BRAFV600E‐mutant melanoma. This report by the Vemurafenib Dermatology Working Group presents the characteristics ...of dermatologic adverse events (AEs) that occur in vemurafenib‐treated patients, including cutaneous squamous cell carcinoma (cuSCC).
Methods.
Dermatologic AEs were assessed from three ongoing trials of BRAFV600E mutation‐positive advanced melanoma. Histologic central review and genetic characterization were completed for a subset of cuSCC lesions.
Results.
A total of 520 patients received vemurafenib. The most commonly reported AEs were dermatologic AEs, occurring in 92%–95% of patients. Rash was the most common AE (64%–75% of patients), and the most common types were rash not otherwise specified, erythema, maculopapular rash, and folliculitis. Rash development did not appear to correlate with tumor response. Photosensitivity occurred in 35%–63% of patients, and palmar‐plantar erythrodysesthesia (PPE) occurred in 8%–10% of patients. The severity of rash, photosensitivity, and PPE were mainly grade 1 or 2. In all, 19%–26% of patients developed cuSCC, mostly keratoacanthomas (KAs). The majority of patients with cuSCC continued therapy without dose reduction after resection. Genetic analysis of 29 cuSCC/KA samples demonstrated HRAS mutations in 41%.
Conclusions.
Dermatologic AEs associated with vemurafenib treatment in patients with melanoma were generally manageable with supportive care measures. Dose interruptions and/or reductions were required in <10% of patients.
摘要
背景. 维罗非尼已获批用于晚期BRAFV600E 突变黑色素瘤患者的治疗。本项维罗非尼皮肤工作组报告描述了接受维罗非尼治疗患者的皮肤不良事件（AE）特征，包括出现皮肤鳞状细胞癌（cuSCC）。
方法. 本研究对3项正在进行的BRAFV600E突变阳性晚期黑色素瘤试验中的皮肤AE进行了评估。对cuSCC病灶亚组进行了组织学中心评估和遗传学特征分析。
结果. 共 520 例患者接受维罗非尼治疗。最常见AE为皮肤AE，发生率为92%~95%。其中常见者为皮疹（64%~75%），最常见类型包括未作特别说明的皮疹、红斑、斑丘疹与毛囊炎。皮疹发生与肿瘤缓解无关。35%~63%的患者出现光敏性反应，8%~10%的患者出现掌跖红肿（PPE）。皮疹、光敏性反应及PPE多为1~2级。总体而言，19%~26%的患者出现cuSCC，大部分为角化棘皮瘤（KA）。绝大多数cuSCC在手术切除后仍以原剂量维罗非尼继续治疗。29例cuSCC/KA样本基因检测显示，41%出现HRAS突变。
结论. 黑色素瘤患者中，维罗非尼相关皮肤AE通常可采用支持治疗措施处治，但<10%的患者需要停药和/或减量治疗。
Vemurafenib has been approved for the treatment of patients with advanced BRAFV600E‐mutant melanoma. The most commonly reported adverse events were dermatologic conditions, occurring in 92%–95% of patients. Dose interruptions and/or reductions were required in <10% of patients.
Checkpoint inhibitor therapy has been a breakthrough in cancer research, but only some patients with cancer derive substantial benefit. Although mechanisms underlying sensitivity and resistance to ...checkpoint inhibitors are being elucidated, the importance of organ-specific regulation of immunity is currently underappreciated. Here, we call for a greater understanding of tissue-specific immunoregulation, namely, "tissue-specific immunostats," to make advances in treatments for cancer. A better understanding of how individual organs at baseline regulate the immune system could enable an improved precision medicine approach to cancer immunotherapy.
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