Tumor cell extravasation is a key step during cancer metastasis, yet the precise mechanisms that regulate this dynamic process are unclear. We utilized a high-resolution time-lapse intravital imaging approach to visualize the dynamics of cancer cell extravasation in vivo. During intravascular migration, cancer cells form protrusive structures identified as invadopodia by their enrichment of MT1-MMP, cortactin, Tks4, and importantly Tks5, which localizes exclusively to invadopodia. Cancer cells extend invadopodia through the endothelium into the extravascular stroma prior to their extravasation at endothelial junctions. Genetic or pharmacological inhibition of invadopodia initiation (cortactin), maturation (Tks5), or function (Tks4) resulted in an abrogation of cancer cell extravasation and metastatic colony formation in an experimental mouse lung metastasis model. This provides direct evidence of a functional role for invadopodia during cancer cell extravasation and distant metastasis and reveals an opportunity for therapeutic intervention in this clinically important process.

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Clustering of the high affinity IgE receptor (FcεRI) in mast cells leads to degranulation and production of numerous cytokines and lipid mediators that promote allergic inflammation. Initiation of FcεRI signaling involves rapid tyrosine phosphorylation of FcεRI and membrane-localized adaptor proteins that recruit additional SH2 domain-containing proteins that dynamically regulate downstream signaling. SH2 domain-containing phosphatase-2 (SHP2) is a protein-tyrosine phosphatase implicated in FcεRI signaling, but whose function is not well defined. In this study, using a mouse model allowing temporal shp2 inactivation in bone marrow-derived mast cells (BMMCs), we provide insights into SHP2 functions in the FcεRI pathway. Although no overt defects in FcεRI-induced tyrosine phosphorylation were observed in SHP2 knock-out (KO) BMMCs, several proteins including Lyn and Syk kinases displayed extended phosphorylation kinetics compared with wild-type BMMCs. SHP2 was dispensable for FcεRI-induced degranulation of BMMCs, but was required for maximal activation of Erk and Jnk mitogen-activated protein kinases. SHP2 KO BMMCs displayed several phenotypes associated with reduced Fyn activity, including elevated phosphorylation of the inhibitory pY531 site in Fyn, impaired signaling to Grb2-associated binder 2, Akt/PKB, and IκB kinase, and decreased TNF-α release compared with control cells. This is likely due to elevated Lyn activity in SHP2 KO BMMCs, and the ability of Lyn to antagonize Fyn activity. Overall, our study identifies SHP2 as a positive effector of FcεRI-induced activation of Fyn/Grb2-associated binder 2/Akt and Ras/Erk pathways leading to TNF-α release from mast cells.

BACKGROUND: The phosphatidyl 3-inositol kinase (PI3K)/Akt/mechanistic target of rapamycin (mTOR) pathway frequently is activated in patients with urothelial carcinoma (UC). In the current study, the authors performed a phase 2 study evaluating the efficacy of the panisoform class I PI3K inhibitor buparlisib in patients with platinum-refractory metastatic UC. METHODS: Two cohorts were recruited: an initial genetically unselected cohort and a subsequent expansion cohort of patients with PI3K/Akt/mTOR pathway-altered tumors. The primary endpoint was the 2-month progression-free survival rate. A rate of ≥80% was considered promising using a Simon 2-stage minimax design. Secondary endpoints included safety and correlation of markers of PI3K pathway activation with outcome. RESULTS: Six of 13 evaluable patients within the initial cohort demonstrated stable disease and 1 demonstrated a partial response, which was below the cutoff of 9 patients required to proceed to stage 2. Three of the patients with stable disease and the patient with a partial response harbored somatic TSC1 alterations. Four patients subsequently were recruited onto an expansion cohort: 3 patients with TSC1 alterations and 1 patient with a PIK3CA-activating mutation. No patient achieved disease control at 8 weeks and accrual was halted. Of the 19 patients evaluable for toxicity, 17 demonstrated treatment-related toxicities, 2 of whom had to discontinue therapy. CONCLUSIONS: Buparlisib was found to demonstrate modest activity in patients with metastatic UC whose tumors harbored TSC1 loss of function alterations; however, this was not a robust predictor of response to buparlisib. The pattern of genetic coalterations likely influences drug sensitivity. Given the modest clinical activity and substantial toxicity of buparlisib, future trials of PI3K inhibitors in patients with UC should focus on isoform-selective PI3K inhibitors in genomically selected patients. Cancer 2020;126:4532-4544.

To evaluate trends in oncologic characteristics and outcomes, as well as perioperative management, among patients undergoing radical cystectomy at Memorial Sloan Kettering from 1995 to 2015. Materials and Methods:We retrospectively reviewed our institutional database to analyze changes in disease recurrence probability, cancer-specific and all-cause mortality, incidence of muscle-invasive bladder cancer, use of perioperative chemotherapy, rate of positive soft-tissue surgical margins, and lymph node yield. Results:In 2,740 patients with non-metastatic urothelial carcinoma undergoing radical cystectomy from 1995 to 2015, the 5-year probability of disease recurrence decreased from a peak of 42% in 1997 to 34% in 2013 (p=0.045), while 5-year probability of cancer-specific mortality likewise declined from 36% in 1997 to 24% in 2013 (p=0.009). Incidence of non-muscle-invasive disease before radical cystectomy did not change, comprising 30%-35% of patients across the study period. Use of neoadjuvant chemotherapy rose significantly: 57% of patients with muscleinvasive bladder cancer from 2010 to 2015 received it. We observed a corresponding rise in complete pathologic response (pT0) at radical cystectomy, as well as decreasing positive softtissue surgical margins (10% to 2.5%) and rising lymph node yield (7 to 24) from 1995 to 2015.Conclusions: Over a 21-year period, outcomes after radical cystectomy at our institution improved significantly, as probability of recurrence and cancer-specific mortality decreased. Increasing utilization of neoadjuvant chemotherapy, rising pT0 rates, decreased positive soft-tissue surgical margins, and increasing lymph node yields likely contributed, suggesting that optimized surgical and perioperative care led to improved cancer outcomes in patients undergoing radical cystectomy.