A novel sirtuin 2 (SIRT2) inhibitor with p53-dependent pro-apoptotic activity in non-small cell lung cancer.

Sirtuin 2 (SIRT2) is an NAD(+)-dependent protein deacetylase whose targets include histone H4 lysine 16, p53, and α-tubulin. Because deacetylation of p53 regulates its effect on apoptosis, pharmacological inhibition of SIRT2-dependent p53 deacetylation is of great therapeutic interest for the treatment of cancer. Here, we have identified two structurally related compounds, AEM1 and AEM2, which are selective inhibitors of SIRT2 (IC50 values of 18.5 and 3.8 µM, respectively), but show only weak effects on other sirtuins such as SIRT1, SIRT3, and yeast Sir2. Interestingly, both compounds sensitized non-small cell lung cancer cell lines toward the induction of apoptosis by the DNA-damaging agent etoposide. Importantly, this sensitization was dependent on the presence of functional p53, thus establishing a link between SIRT2 inhibition by these compounds and p53 activation. Further, treatment with AEM1 and AEM2 led to elevated levels of p53 acetylation and to increased expression of CDKN1A, which encodes the cell cycle regulator p21(WAF1), as well as the pro-apoptotic genes PUMA and NOXA, three transcriptional targets of p53. Altogether, our data suggest that inhibition of SIRT2 by these compounds causes increased activation of p53 by decreasing SIRT2-dependent p53 deacetylation. These compounds thus provide a good opportunity for lead optimization and drug development to target p53-proficient cancers.

Multinational proficiency tests for EGFR exon 20 insertions reveal that the assay design matters.

Insertion mutations in exon 20 of the epidermal growth factor receptor gene (EGFR exon20ins) are rare, heterogeneous alterations observed in non-small cell lung cancer (NSCLC). With a few exceptions, they are associated with primary resistance to established EGFR tyrosine kinase inhibitors (TKIs). As patients carrying EGFR exon20ins may be eligible for treatment with novel therapeutics-the bispecific antibody amivantamab, the TKI mobocertinib, or potential future innovations-they need to be identified reliably in clinical practice for which quality-based routine genetic testing is crucial. Spearheaded by the German Quality Assurance Initiative Pathology two international proficiency tests were run, assessing the performance of 104 participating institutes detecting EGFR exon20ins in tissue and/or plasma samples. EGFR exon20ins were most reliably identified using next-generation sequencing (NGS). Interestingly, success rates of institutes using commercially available mutation-/allele-specific quantitative (q)PCR were below 30% for tissue samples and 0% for plasma samples. Most of these mutation-/allele-specific (q)PCR assays are not designed to detect the whole spectrum of EGFR exon20ins mutations leading to false negative results. These data suggest that NGS is a suitable method to detect EGFR exon20ins in various types of patient samples and is superior to the detection spectrum of commercially available assays.

Buparlisib in combination with tamoxifen in pretreated patients with hormone receptor-positive, HER2-negative advanced breast cancer molecularly stratified for PIK3CA mutations and loss of PTEN expression.

The PIKTAM study evaluated the efficacy and safety of the PI3K inhibitor buparlisib in combination with tamoxifen in hormone receptor-positive (HR+ ), HER2-negative advanced breast cancer patients after failure of prior endocrine therapy. In this open-label, single-arm phase II trial, 25 patients were enrolled in 11 sites in Germany. Patients were stratified according to PIK3CA mutation status (tissue and cfDNA from serum samples) and/or loss of PTEN expression. Patients received buparlisib (100 mg) and tamoxifen (20 mg) once daily on a continuous schedule (28-day cycle) until progression or unacceptable toxicity. Primary endpoint was overall 6-month progression-free survival (PFS) rate. Key secondary endpoints included the 6-month PFS rate in subpopulations, PFS, overall survival, overall response rate (ORR), disease control rate (DCR), and safety. Overall, the 6-month PFS rate was 33.3% (n/N = 7/21, one-sided 95% CI 16.8-100) and median PFS was 6.1 (CI 2.6-10.6) months. The ORR and DCR were 12.5% and 44%. The PIK3CA-mutated subgroup consistently showed the highest 6-month PFS rate (62.5%, n/N = 5/8), median PFS (8.7 months), ORR (40%), and DCR (80%). No new safety signals emerged. Most common adverse events were gastrointestinal disorders (56%), psychiatric/mood disorders (48%), skin rash/hypersensitivity (44%), cardiovascular (40%), and hepatic (32%) events. The trial was prematurely terminated due to the substantially altered risk-benefit profile of buparlisib. Nevertheless, PIK3CA mutations emerged as a clinically feasible and useful biomarker for combined PI3K inhibition and endocrine therapy in patients with HR+ breast cancer. Further biomarker-stratified studies with isoform-specific PI3K inhibitors are warranted. EudraCT No: 2014-000599-24.

Functional screening identifies aryl hydrocarbon receptor as suppressor of lung cancer metastasis.

Lung cancer mortality largely results from metastasis. Despite curative surgery many patients with early-stage non-small cell lung cancer ultimately succumb to metastatic relapse. Current risk reduction strategies based on cytotoxic chemotherapy and radiation have only modest activity. Against this background, we functionally screened for novel metastasis modulators using a barcoded shRNA library and an orthotopic lung cancer model. We identified aryl hydrocarbon receptor (AHR), a sensor of xenobiotic chemicals and transcription factor, as suppressor of lung cancer metastasis. Knockdown of endogenous AHR induces epithelial-mesenchymal transition signatures, increases invasiveness of lung cancer cells in vitro and metastasis formation in vivo. Low intratumoral AHR expression associates with inferior outcome of patients with resected lung adenocarcinomas. Mechanistically, AHR triggers ATF4 signaling and represses matrix metalloproteinase activity, both counteracting metastatic programs. These findings link the xenobiotic defense system with control of lung cancer progression. AHR-regulated pathways are promising targets for innovative anti-metastatic strategies.

Feasibility of preemptive biomarker profiling for personalised early clinical drug development at a Comprehensive Cancer Center.

PURPOSE: Multiple investigational drugs are currently explored in cancer patient populations defined by specific biomarkers. This demands a new process of patient selection for clinical trials. PATIENTS AND METHODS: Starting January 1, 2012, preemptive biomarker profiling was offered at the West German Cancer Center to all patients with advanced non-small-cell lung (NSCLC) or colorectal cancer (CRC), who met generic study inclusion criteria. Tumour specimens were subjected to prespecified profiling algorithms to detect 'actionable biomarkers' by amplicon sequencing, in situ hybridisation and immunohistochemistry. The clinical course was closely monitored to offer trial participation whenever applicable. RESULTS: Within 12 months, 267 patients (188 NSCLC, 79 CRC) were profiled. Estimated additional cost for biomarker profiling was 219615.51 EUR excluding histopathology workup and administration. The most prevalent biomarkers in pulmonary adenocarcinoma were KRAS mutations (29%), loss of PTEN expression (18%), EGFR mutations (9%), HER2 amplification (5%) and BRAF mutations (3%), while the prevalence of ALK translocations and PIK3CA mutations was extremely low. In pulmonary squamous cell carcinoma FGFR1 amplifications were found in 15%, PTEN expression was lost in 20% and DDR2 was mutated in a single case. KRAS mutations (41%) predominated in CRC, followed by loss of PTEN expression (16%), PIK3CA (5%) and BRAF (5%) mutations. So far 13 patients (5%) have entered biomarker-stratified clinical trials. Therapeutic decisions for approved drugs were guided in another 45 patients (17%). CONCLUSION: Preemptive biomarker profiling can be implemented into the diagnostic algorithm of a large Comprehensive Cancer Center. Substantial investments in diagnostics and administration are required.