Retinoblastoma Expression and Targeting by CDK4/6 Inhibitors in Small Cell Lung Cancer.

The canonical model of "small cell lung cancer" (SCLC) depicts tumors arising from dual inactivation of TP53 and RB1. However, many genomic studies have persistently identified tumors with no RB1 mutations. Here, we examined RB1 protein expression and function in SCLC. RB1 expression was examined by IHC analysis of 62 human SCLC tumors. These studies showed that ∼14% of SCLC tumors expressed abundant RB1 protein, which is associated with neuroendocrine gene expression and is enriched in YAP1 expression, but no other lineage proteins that stratify SCLC. SCLC cells and xenograft tumors with RB1 protein expression were sensitive to growth inhibition by the CDK4/6 inhibitor palbociclib, and this inhibition was shown to be dependent on RB1 expression by CRISPR knockout. Furthermore, a patient with biopsy-validated wild-type RB1 SCLC who received the CDK4/6 inhibitor abemaciclib demonstrated a dramatic decrease in mutant TP53 ctDNA allelic fraction from 62.1% to 0.4% and decreased tumor mass on CT scans. Importantly, IHC of the diagnostic biopsy specimen showed RB1 positivity. Finally, we identified a transcriptomics-based RB1 loss-of-function signature that discriminates between SCLC cells with or without RB1 protein expression and validated it in the patient who was responsive to abemaciclib, suggesting its potential use to predict CDK4/6 inhibitor response in patients with SCLC. Our study demonstrates that RB1 protein is an actionable target in a subgroup of SCLC, a cancer that exhibits no currently targetable mutations.

Report of a Rare Case of Spindle Cell Ameloblastic Carcinoma and the Diagnostic Utility of Immunohistochemistry.

Ameloblastic carcinoma is a rare aggressive malignant epithelial odontogenic tumor. The spindle cell variant of ameloblastic carcinoma (SCAC) is exceedingly rare with 15 cases of SCAC having been reported. Therefore, because of the paucity of cases in literature related to SCAC, the biological behavior of the entity has not been well evaluated. Herein the authors report a case of incidentally diagnosed SCAC in a 20-year-old woman identified on imaging as part of the evaluation of a work-related facial injury. Histologically, the tumor had background of cystic ameloblastoma with areas of dense hypercellular spindle cells with short-to-long intersecting fascicles and occasional herringbone pattern intermixed with solid epithelial nests. Both the epithelial and spindle cells were positive for cytokeratin including cytokeratin 19, D2-40, and transducin-like enhancer of split proteins-1 immunohistochemical stains. The patient was followed for 18 months with no evidence of recurrence or metastasis. To the knowledge this is a first case of reporting D2-40 positivity in spindle ameloblastic carcinoma and this immunostain could be used as helpful marker to diagnose this entity.

Non-O blood group thrombotic thrombocytopenic purpura patients take longer to recover as measured by number of therapeutic plasma exchanges needed for platelet recovery.

INTRODUCTION: Therapeutic plasma exchange (TPE) is mainstay therapy for thrombotic thrombocytopenic purpura (TTP). However, it remains controversial if ABO type influences diagnosis or time to remission. MATERIALS AND METHODS: We investigated if ABO type influences length of TPE regimen in TTP patients with ADAMTS13 deficiency at our institution. Seventy out of 71 patients with suspected TTP who had ADAMTS13 activity measured were included. ADAMTS13 activity <10% defined those with idiopathic/acquired TTP (41/70). RESULTS: We found that among patients with ADAMTS13 deficiency, non-O patients required a significantly greater number of TPE (NoP) compared to O patients (p = 0.039). Additionally, patients with ADAMTS13 deficiency regardless of ABO type needed more TPE to achieve platelet recovery compared to those patients without deficiency (p = 0.00002). In regard to other variables that may affect response to therapy in TTP patients, we found no association between obesity and NoP; however, obesity rate was higher among ADAMTS13 deficient patients compared to overall obesity rate of our regional general population. Likewise, were found that blood group O did not occur with greater frequency in our cohort. CONCLUSIONS: Our data indicates that ABO may affect the NoP patients required for disease remission. We found that non-O patients needed more procedures to overcome their disease. Further work with greater number of patients will be needed to determine if specific non-O blood types require more procedures to recover their platelet count.

Reciprocal expression of INSM1 and YAP1 defines subgroups in small cell lung cancer.

The majority of small cell lung cancer (SCLC) patients demonstrate initial chemo-sensitivity, whereas a distinct subgroup of SCLC patients, termed chemo-refractory, do not respond to treatment. There is little understanding of how to distinguish these patients prior to disease treatment. Here we used gene expression profiling to stratify SCLC into subgroups and characterized a molecular phenotype that may identify, in part, chemo-refractive SCLC patients. Two subgroups of SCLC were identified in both cell lines and tumors by the reciprocal expression of two genes; INSM1, a neuroendocrine transcription factor, and YAP1, a key mediator of the Hippo pathway. The great majority of tumors expressed INSM1, which was prognostic for increased progression-free survival and associated with chemo-sensitivity in cell lines. YAP1 is expressed in a minority of SCLC tumors and was shown in cell lines to be downstream of the retinoblastoma protein (RB1) and associated with decreased drug sensitivity. RB1 expression in SCLC cell lines sensitizes them to CDK4/6 inhibitors. Wild-type RB1 mutation status, used as a surrogate marker of YAP1 expression, was prognostic for decreased patient survival and increased chemo-refractory tumor response. Thus, the reciprocal expression of INSM1 and YAP1 appears to stratify SCLC into distinct subgroups and may be useful, along with RB1 mutation status, to identify chemo-refractory SCLC patients.

Evaluating the role of phase I expansion cohorts in oncologic drug development.

Importance Use of expansion cohorts (EC) in phase I trials is increasing. However, the utility of phase I EC in aiding drug development is unclear. We sought to determine factors associated with the inclusion of EC in phase I studies and the impact of EC on subsequent clinical development. Methods We performed a systematic review of all phase I trials published in the Journal of Clinical Oncology between June 2004 and May 2014. Presence of an EC, number of participants, funding source, class of agent, tumor type, and maximum tolerated dose (MTD)/recommended phase 2 dose (RP2D) were identified. Subsequent conduct of phase II studies and FDA approval of the study agent was also assessed. Results We identified 252 phase I studies. An EC was included in 105 studies. Average accrual on EC studies was 47 compared to 31 in studies without EC (p < 0.0001). There was no impact of time on the inclusion of EC. Only 4 % of phase I studies with an EC provided sample size justification. Source of funding had the only significant association with inclusion of EC. Addition of a phase I EC did not impact the phase I MTD/RP2D, subsequent phase II trial, or FDA approval. Conclusion The importance of including an EC in phase I trials is subject to ongoing debate. Our results demonstrated little benefit to including EC in phase I studies. These findings support that innovative design strategies are needed to optimize the utility of EC in phase I studies.

RICTOR amplification identifies a subgroup in small cell lung cancer and predicts response to drugs targeting mTOR.

Small cell lung cancer (SCLC) is an aggressive cancer that represents ~15% of all lung cancers. Currently there are no targeted therapies to treat SCLC. Our genomic analysis of a metastatic SCLC cohort identified recurrent RICTOR amplification. Here, we examine the translational potential of this observation. RICTOR was the most frequently amplified gene observed (~14% patients), and co-amplified with FGF10 and IL7R on chromosome 5p13. RICTOR copy number variation correlated with RICTOR protein expression in SCLC cells. In parallel, cells with RICTOR copy number (CN) gain showed increased sensitivity to three mTOR inhibitors, AZD8055, AZD2014 and INK128 in cell growth assays, with AZD2014 demonstrating the best inhibition of downstream signaling. SCLC cells with RICTOR CN gain also migrated more rapidly in chemotaxis and scratch wound assays and were again more sensitive to mTOR inhibitors. The overall survival in SCLC patients with RICTOR amplification was significantly decreased (p = 0.021). Taken together, our results suggest that SCLC patients with RICTOR amplification may constitute a clinically important subgroup because of their potential response to mTORC1/2 inhibitors.

Evaluation of diagnostic values of photodynamic diagnosis in identifying the dermal and mucosal squamous cell carcinoma.

OBJECTIVES: We conducted a study to determine and compare the efficacy of pathology and photodynamic studies in establishing diagnosis of malignant dermal and mucosal lesions. METHODS AND PATIENTS: This descriptive cross-sectional study was performed on 40 patients suspected of SCC (squamous cell carcinoma). First, in PDD (photodynamic diagnosis) photosensitizing agent was applied to the lesion, and after 4-5h the fluorescence spectrum was detected by laser radiation. Based on fluorescence intensity, normal area was differentiated from malignant area. Also, biopsy samples from these suspected areas were sent to pathology simultaneously. Data were analyzed with SPSS v.16. The distribution of nominal variables was compared using the Chi-square test. Diagnostic index for photodynamic diagnosis were calculated. A two-sided p-value<0.05 was considered to be statistically significant. RESULTS: In 27 cases (90%), results of pathology and photodynamic studies similarly showed malignancy. In 8 cases (80%), results of pathology and photodynamic studies similarly showed non-malignant lesion. But in five cases (12.5%) the results of pathology and photodynamic studies were not the same. This difference was not statistically significant showed by the Chi-square test analysis (p-value>0.05). A sensitivity of 90%, specificity of 80%, accuracy of 87.5%, positive predictive value (PPV) of 93%, negative predictive value (NPV) of 72%, positive likelihood ratio (PLR) of 4.5, negative likelihood ratio(NLR) of 0.125 were found in diagnosing SCC for photodynamic studies. CONCLUSION: Photodynamic diagnosis is a useful non-invasive initial step in the diagnostic work-up of patients with suspected malignant lesions (SCC). In this work we have studied 40 SCC suspicious patients using PDD method and successfully carried out 27 cases as malignant all of which were matching with pathologic results. This outcome can prove both accuracy and reliability of PDD method for detecting SCC lesions on head and neck regions. Also PDD can fully demarcate the lesion peripheries less invasively as well as preserving much more time and effort. Although PDD method is a bit more expensive that biopsy and pathology but great advantages can easily cover this issue. We recommend PDD as a useful easy technique to visualize and detect the extension of the tumor preoperatively.