Phase I/II Study of Combined BCL-xL and MEK Inhibition with Navitoclax and Trametinib in KRAS or NRAS Mutant Advanced Solid Tumors.

PURPOSE: MEK inhibitors (MEKi) lack monotherapy efficacy in most RAS-mutant cancers. BCL-xL is an anti-apoptotic protein identified by a synthetic lethal shRNA screen as a key suppressor of apoptotic response to MEKi. PATIENTS AND METHODS: We conducted a dose escalation study (NCT02079740) of the BCL-xL inhibitor navitoclax and MEKi trametinib in patients with RAS-mutant tumors with expansion cohorts for: pancreatic, gynecologic (GYN), non-small cell lung cancer (NSCLC), and other cancers harboring KRAS/NRAS mutations. Paired pretreatment and day 15 tumor biopsies and serial cell-free (cf)DNA were analyzed. RESULTS: A total of 91 patients initiated treatment, with 38 in dose escalation. Fifty-eight percent had ≥3 prior therapies. A total of 15 patients (17%) had colorectal cancer, 19 (11%) pancreatic, 15 (17%) NSCLC, and 32 (35%) GYN cancers. The recommended phase II dose (RP2D) was established as trametinib 2 mg daily days 1 to 14 and navitoclax 250 mg daily days 1 to 28 of each cycle. Most common adverse events included diarrhea, thrombocytopenia, increased AST/ALT, and acneiform rash. At RP2D, 8 of 49 (16%) evaluable patients achieved partial response (PR). Disease-specific differences in efficacy were noted. In patients with GYN at the RP2D, 7 of 21 (33%) achieved a PR and median duration of response 8.2 months. No PRs occurred in patients with colorectal cancer, NSCLC, or pancreatic cancer. MAPK pathway inhibition was observed in on-treatment tumor biopsies. Reductions in KRAS/NRAS mutation levels in cfDNA correlated with clinical benefit. CONCLUSIONS: Navitoclax in combination with trametinib was tolerable. Durable clinical responses were observed in patients with RAS-mutant GYN cancers, warranting further evaluation in this population.

Pathological complete response, long-term outcomes, and recurrence patterns in HER2-low versus HER2-zero breast cancer after neoadjuvant chemotherapy.

BACKGROUND: The interest in HER2-low breast cancer (BC) has increased in recent years with the development of novel anti-HER2 antibody-drug conjugates. Here, we investigated the clinical outcomes and relapse patterns of patients with HER2-low or -zero BCs in an Asian population. METHODS: We retrospectively identified HER2-low or -zero BC patients with stage I-III tumours who were treated with neoadjuvant chemotherapy and underwent curative surgery, between 2014 and 2018 at Asan Medical Center, Seoul, Korea. RESULTS: A total of 818 and 754 HER2-zero and HER2-low BC patients, respectively, were consecutively included in this analysis. The HER2-low group had more hormone receptor [HR]-positive patients (81% versus 56%, P < 0.001). The HER2-zero group had a higher proportion of patients who achieved pathological complete response (pCR) (14.7% versus 9.8%, P = 0.003); however, no significant differences of pCR rate by HER2 status were identified in the HR-positive (P = 0.4) and HR-negative groups (P = 0.3) when analysed separately. The HER2-low BC cases had higher 5-year overall survival (OS) and disease-free survival (DFS) rates (P < 0.001 for OS; P = 0.002 for DFS); however, no differences were observed in terms of OS and DFS by HER2 status in the HR-positive group (P = 0.21 for OS and P = 0.66 for DFS). CONCLUSIONS: Our current findings do not support that HER2-low BC had different biology and clinical features compared to HER2-zero BC in patients who treated with neoadjuvant chemotherapy. However, the prognostic impact of HER2-low status in BC remains controversial; thus warranting further research.

NFI transcription factors provide chromatin access to maintain stem cell identity while preventing unintended lineage fate choices.

Tissue homeostasis and regeneration rely on resident stem cells (SCs), whose behaviour is regulated through niche-dependent crosstalk. The mechanisms underlying SC identity are still unfolding. Here, using spatiotemporal gene ablation in murine hair follicles, we uncover a critical role for the transcription factors (TFs) nuclear factor IB (NFIB) and IX (NFIX) in maintaining SC identity. Without NFI TFs, SCs lose their hair-regenerating capability, and produce skin bearing striking resemblance to irreversible human alopecia, which also displays reduced NFIs. Through single-cell transcriptomics, ATAC-Seq and ChIP-Seq profiling, we expose a key role for NFIB and NFIX in governing super-enhancer maintenance of the key hair follicle SC-specific TF genes. When NFIB and NFIX are genetically removed, the stemness epigenetic landscape is lost. Super-enhancers driving SC identity are decommissioned, while unwanted lineages are de-repressed ectopically. Together, our findings expose NFIB and NFIX as crucial rheostats of tissue homeostasis, functioning to safeguard the SC epigenome from a breach in lineage confinement that otherwise triggers irreversible tissue degeneration.

Mutation Burden and I Index for Detection of Microsatellite Instability in Colorectal Cancer by Targeted Next-Generation Sequencing.

Next-generation sequencing (NGS) panels are widely used for defining tumor mutation profiles and determining treatment approaches. We performed targeted NGS with 382 colorectal cancer genes with known microsatellite instability (MSI). After exclusion of germline alterations, the load of somatic mutations and small insertion/deletion (indel) alterations were determined. In the test set, 79 patients with 41 microsatellite-stable (MSS) and 38 MSI tumors were included. There were 120 MSS and eight MSI-high tumors in the validation set. The number of somatic mutations of whole samples were distinguished into three groups: mutant functional polymerase epsilon catalytic subunit, MSI, and MSS tumors. The median numbers of somatic and indel mutations in MSI tumors were higher. The indel mutation to whole mutation ratio (I index) was higher in MSI tumors. Hypermutation and low I index of polymerase epsilon catalytic subunit mutant tumors, a somatic mutation load cut-off of ≥40, and an I index of ≥9% were selected as the criteria for detecting MSI tumors with high sensitivity and specificity. With the analysis of alteration patterns of homopolymer genes, a higher median number of homopolymer mutations in MSI tumors was observed. Mutated homopolymer ≥5 was selected as the criterion for detecting MSI tumors. MSI in colorectal cancer can be detected by targeted NGS panels with high sensitivity and specificity using somatic mutation load and I index.

Chemical composition of post-harvest biomass burning aerosols in Gwangju, Korea.

The main objective of this study was to investigate the chemical characteristics of post-harvest biomass burning aerosols from field burning of barley straw in late spring and rice straw in late fall in rural areas of Korea. A 12-hr integrated intensive sampling of particulate matter (PM) with an aerodynamic diameter less than or equal to 10 microm (PM10) and PM with an aerodynamic diameter less than or equal to 2.5 microm (PM2.5) biomass burning aerosols had been conducted continuously in Gwangju, Korea, during two biomass burning periods: June 4--15, 2001, and October 8--November 14, 2002. The fine and coarse particles of biomass burning aerosols were analyzed for mass and ionic, elemental, and carbonaceous species. The average fine and coarse mass concentrations of biomass burning aerosols were, respectively, 129.6 and 24.2 microg/m3 in June 2001 and 47.1 and 33.2 microg/m3 in October--November 2002. An exceptionally high PM2.5 concentration of 157.8 microg/m3 was observed during biomass burning events under stagnant atmospheric conditions. In the fine mode, chlorine and potassium were unusually rich because of the high content of semi-arid vegetation. Both organic carbon (OC) and elemental carbon increased during the biomass burning periods, with the former exhibiting a higher abundance. PM from the open field burning of agricultural waste has an adverse impact on local air quality and regional climate.

Implantation metastasis along the stereotactic biopsy tract in anaplastic astrocytoma: a case report.

OBJECTIVE AND IMPORTANCE: Stereotactic biopsy for brain lesion is usually a safe procedure and the reported rate of complication is minimal. Moreover, local seeding along the trajectory of the stereotactic biopsy is arare complication. The authors report a case of metastatic implantation along the trajectory of the stereotactic biopsy in anaplastic astrocytoma. CLINICAL PRESENTATION: A 64-year-old man who presented with a one-month history of speech and memory disturbance underwent magnetic resonance (MR) imaging that disclosed a large mass in the left basal ganglia and medial temporal region. INTERVENTION: Under the impression of high-grade glioma, computed tomography guided stereotactic biopsy was performed using the Riechert-Mundinger system. The histologic diagnosis was anaplastic astrocytoma. MR images after two cycles of chemotherapy showed a small enhancing portion in the middle of the biopsy tract, which was considered a surgical artifact and not included in the field of the following conventional fractionated radiation therapy. MR images three months after the completion of radiation therapy revealed that the enhancing portion had become a larger mass irrespective of good control of the primary tumor. CONCLUSION: Our findings suggest that tumor seeding along the stereotactic biopsy trajectory must be considered if an enhancing lesion appears in the MR image following the stereotactic biopsy. The cause and the prevention of implantation metastasis along the stereotactic biopsy tract are also discussed.