Discoidin Domain Receptor Tyrosine Kinase 1 (DDR1) Is a Novel Therapeutic Target in Liposarcoma: A Tissue Microarray Study.

BACKGROUND: Liposarcoma is the most commonly diagnosed subtype of soft tissue sarcoma. As these tumors often arise near vital organs and neurovascular structures, complete resection can be challenging; consequently, recurrence rates are high. Additionally, available chemotherapeutic agents have shown limited benefit and substantial toxicities. There is, therefore, a clear and unmet need for novel therapeutics for liposarcoma. Discoidin domain receptor tyrosine kinase 1 (DDR1) is involved in adhesion, proliferation, differentiation, migration, and metastasis in several cancers. However, the expression and clinical importance of DDR1 in liposarcoma are unknown. QUESTIONS/PURPOSES: The purposes of this study were to assess (1) the expression, (2) the association between DDR1 and survival, and (3) the functional roles of DDR1 in liposarcoma. METHODS: The correlation between DDR1 expression in tumor tissues and clinicopathological features and survival was assessed via immunohistochemical staining of a liposarcoma tissue microarray. It contained 53 samples from 42 patients with liposarcoma and 11 patients with lipoma. The association between DDR1 and survival in liposarcoma was analyzed by Kaplan-Meier plots and log-rank tests. The DDR1 knockout liposarcoma cell lines were generated by CRISPR-Cas9 technology. The DDR1-specific and highly selective DDR1 inhibitor 7RH was applied to determine the impact of DDR1 expression on liposarcoma cell growth and proliferation. In addition, the effect of DDR1 inhibition on liposarcoma growth was further accessed in a three-dimensional cell culture model to mimic DDR1 effects in vivo. RESULTS: The results demonstrate elevated expression of DDR1 in all liposarcoma subtypes relative to benign lipomas. Specifically, high DDR1 expression was seen in 55% (23 of 42) of liposarcomas and no benign lipomas. However, DDR1 expression was not found to be associated with poor survival in patients with liposarcoma. DDR1 knockout or treatment of 7RH showed decreased liposarcoma cell growth and proliferation. CONCLUSION: DDR1 is aberrantly expressed in liposarcoma, and it contributes to several markers of oncogenesis in these tumors. CLINICAL RELEVANCE: This work supports DDR1 as a promising therapeutic target in liposarcoma.

What Clinical Trials Are Needed for Treatment of Leiomyosarcoma?

OPINION STATEMENT: Leiomyosarcoma is one of the most common subtypes of soft tissue sarcomas accounting for approximately 20% of sarcomas. As leiomyosarcoma patients frequently develop metastatic disease, effective systemic therapies are needed to improve clinical outcomes. The overall activity of the currently available conventional systemic therapies and the prognosis of patients with advanced and/or metastatic disease are poor. As such, the treatment of this patient population remains challenging. As a result, there is a clear unmet medical need, and designing and performing meaningful clinical studies are of utmost importance to improve the prognosis of this patient group. Therefore, the aim of this review is to briefly summarize state-of-the-art treatments for leiomyosarcoma patients and to describe trial characteristics needed for informative clinical studies.

A nonrandom association of breast implants and the formation of desmoid tumors.

BACKGROUND: Studies suggest that surgical breast augmentation with implants is a risk factor for breast desmoid tumors. The statistical strength of this correlation is unknown, as evidence is limited to anecdotal reports. METHODS: Patients with breast desmoid tumors and a history of breast implants seen at a single center between 2000 and 2021 were identified via radiology, breast, and sarcoma databases. The standardized incidence ratio (SIR) was calculated to assess the correlation between breast desmoid tumors and breast implants. The cases were pooled with published cases for analyses. Progression-free survival curves and hazard ratios were estimated using the Kaplan-Meier method and Cox proportional-hazards modeling. RESULTS: Fourteen patients from one institution and 66 cases in the literature were identified. All patients were female, and the mean age was 38 years old (range 20-66). 63 patients (82%) underwent resection, 9 (12%) received chemotherapy, 3 (4%) received sorafenib, 11 (14%) received hormonal therapy, and 3 (4%) underwent active surveillance. After resection, the 2-year recurrence-free survival rate was 77% (95% CI 65%-89%). The recurrence risk was lower for resection with no residual tumor (R0) compared to microscopic (R1) or macroscopic (R2) residual tumor (HR: 0.15; 95% CI 0.02-0.8; p < 0.05). The SIR was 482 (95% CI 259-775) to 823 (95% CI 442-1322), suggesting a 482-823 times higher risk of developing a breast desmoid tumor after breast augmentation than the general population. CONCLUSION: We present a nonrandom association between breast implants and desmoid tumors. Whether the tumors arise from the surgical trauma or the implant's biomaterial is unknown. When surgery is indicated, negative margins reduce the risk of recurrence.

Axitinib plus pembrolizumab in patients with advanced sarcomas including alveolar soft-part sarcoma: a single-centre, single-arm, phase 2 trial.

BACKGROUND: VEGF promotes an immunosuppressive microenvironment and contributes to immune checkpoint inhibitor resistance in cancer. We aimed to assess the activity of the VEGF receptor tyrosine-kinase inhibitor axitinib plus the anti-PD-1 immune checkpoint inhibitor pembrolizumab in patients with sarcoma. METHODS: This single-centre, single-arm, phase 2 trial was undertaken at a tertiary care academic medical centre in Miami, FL, USA, and participants were recruited from all over the USA and internationally. Patients were eligible if they were aged 16 years or older, and had histologically confirmed advanced or metastatic sarcomas, including alveolar soft-part sarcoma (ASPS); measurable disease with one site amenable to repeated biopsies; an ECOG performance status of 0-1; and progressive disease after previous treatment with at least one line of systemic therapy (unless no standard treatment existed or the patient declined therapy). The first five patients were enrolled in a lead-in cohort and were given axitinib 5 mg orally twice daily and pembrolizumab 200 mg intravenously for 30 min on day 8 and every 3 weeks for cycles of 6 weeks for up to 2 years. Thereafter, patients received escalating doses of axitinib (2-10 mg) plus flat dose pembrolizumab according to the schedule above. The primary endpoint was 3-month progression-free survival. All patients were evaluable for survival and safety analyses. This study is registered with ClinicalTrials.gov, number NCT02636725, and is closed to accrual. FINDINGS: Between April 19, 2016, and Feb 7, 2018, of 36 patients assessed for eligibility, 33 (92%) were enrolled and given study treatment (intention-to-treat population and safety population), 12 (36%) of whom had ASPS. With a median follow-up of 14·7 months (IQR 10·1-19·1), 3-month progression-free survival for all evaluable patients was 65·6% (95% CI 46·6-79·3). For patients with ASPS, 3-month progression-free survival was 72·7% (95% CI 37·1-90·3). The most common grade 3 or 4 treatment-related adverse events included hypertension (five [15%] of 33 patients), autoimmune toxicities (five [15%]), nausea or vomiting (two [6%]), and seizures (two [6%]). Serious treatment-related adverse events occurred in seven (21%) patients, including autoimmune colitis, transaminitis, pneumothorax, haemoptysis, seizures, and hypertriglyceridemia. There were no treatment-related deaths. INTERPRETATION: Axitinib plus pembrolizumab has manageable toxicity and preliminary activity in patients with advanced sarcomas, particularly patients with ASPS, warranting further investigation in randomised controlled trials. FUNDING: Merck, Pfizer, American Cancer Society, and Sylvester Comprehensive Cancer Center.

A phase 1 and randomized controlled phase 2 trial of the safety and efficacy of the combination of gemcitabine and docetaxel with ontuxizumab (MORAb-004) in metastatic soft-tissue sarcomas.

BACKGROUND: Ontuxizumab, a humanized monoclonal antibody, targets endosialin (tumor endothelial marker 1 [TEM-1] or CD248), which is expressed on sarcoma cells and is believed to be involved in tumor angiogenesis. This is the first trial to evaluate ontuxizumab in patients with sarcoma. METHODS: Part 1 was an open-label, dose-finding, safety lead-in: 4, 6, or 8 mg/kg with gemcitabine and docetaxel (G/D; 900 mg/m2 gemcitabine on days 1 and 8 and 75 mg/m2 docetaxel on day 8). In part 2, patients were randomized in a double-blind fashion in 2:1 ratio to ontuxizumab (8 mg/kg) or a placebo with G/D. Randomization was stratified by 4 histological cohorts. RESULTS: In part 2 with 209 patients, no significant difference in progression-free survival between ontuxizumab plus G/D (4.3 months; 95% confidence interval [CI], 2.7-6.3 months) and the placebo plus G/D (5.6 months; 95% CI, 2.6-8.3 months) was observed (P = .67; hazard ratio [HR], 1.07; 95% CI, 0.77-1.49). Similarly, there was no significant difference in median overall survival between the 2 groups: 18.3 months for the ontuxizumab plus G/D group (95% CI, 16.2-21.1 months) and 21.1 months for the placebo plus G/D group (95% CI, 14.2 months to not reached; P = .32; HR, 1.23; 95% CI, 0.82-1.82). No significant differences between the treatment groups occurred for any efficacy parameter by sarcoma cohort. The combination of ontuxizumab plus G/D was generally well tolerated. CONCLUSIONS: Ontuxizumab plus G/D showed no enhanced activity over chemotherapy alone in soft-tissue sarcomas, whereas the safety profile of the combination was consistent with G/D alone.

Latest advances in adult gastrointestinal stromal tumors.

Gastrointestinal stromal tumors (GISTs) are the most common GI tract mesenchymal tumors. GIST patients are optimally managed by a precision medicine approach. Herein, we discuss the latest advances in precision medicine and ongoing clinical trials relevant to GIST. Circulating tumor DNA for detection of mutational changes could replace tissue biopsies and radiographic imaging once validated. Most GISTs are KIT/PDGFRα mutated, and despite the good clinical response to imatinib, treatment is generally not curative, more often due to secondary mutations. New mechanisms to bypass this resistance by inhibiting KIT downstream pathways and by targeting multiple KIT or PDGFRα mutations are being investigated. Immunotherapy for GIST patients is in its infancy. These approaches may lead to more effective, less toxic therapies.

FGFR1 and NTRK3 actionable alterations in "Wild-Type" gastrointestinal stromal tumors.

BACKGROUND: About 10-15% of adult, and most pediatric, gastrointestinal stromal tumors (GIST) lack mutations in KIT, PDGFRA, SDHx, or RAS pathway components (KRAS, BRAF, NF1). The identification of additional mutated genes in this rare subset of tumors can have important clinical benefit to identify altered biological pathways and select targeted therapies. METHODS: We performed comprehensive genomic profiling (CGP) for coding regions in more than 300 cancer-related genes of 186 GISTs to assess for their somatic alterations. RESULTS: We identified 24 GIST lacking alterations in the canonical KIT/PDGFRA/RAS pathways, including 12 without SDHx alterations. These 24 patients were mostly adults (96%). The tumors had a 46% rate of nodal metastases. These 24 GIST were more commonly mutated at 7 genes: ARID1B, ATR, FGFR1, LTK, SUFU, PARK2 and ZNF217. Two tumors harbored FGFR1 gene fusions (FGFR1-HOOK3, FGFR1-TACC1) and one harbored an ETV6-NTRK3 fusion that responded to TRK inhibition. In an independent sample set, we identified 5 GIST cases lacking alterations in the KIT/PDGFRA/SDHx/RAS pathways, including two additional cases with FGFR1-TACC1 and ETV6-NTRK3 fusions. CONCLUSIONS: Using patient demographics, tumor characteristics, and CGP, we show that GIST lacking alterations in canonical genes occur in younger patients, frequently metastasize to lymph nodes, and most contain deleterious genomic alterations, including gene fusions involving FGFR1 and NTRK3. If confirmed in larger series, routine testing for these translocations may be indicated for this subset of GIST. Moreover, these findings can be used to guide personalized treatments for patients with GIST. Trial registration NCT 02576431. Registered October 12, 2015.

Desmoid fibromatosis: MRI features of response to systemic therapy.

OBJECTIVE: Imaging criteria for measuring the response of desmoid fibromatosis to systemic therapy are not well established. We evaluated a series of patients with desmoids who underwent systemic therapy to document magnetic resonance imaging (MRI) features associated with a positive clinical response. MATERIALS AND METHODS: This Institutional Review Board-approved retrospective study included 23 patients (mean age 40.5) with 29 extra-abdominal tumors. Therapeutic regimens included cytotoxic chemotherapy (n = 19), targeted therapy (n = 3), and nonsteroid anti-inflammatory drugs (NSAIDS; n = 1). Clinical effects were categorized as progressive disease, stable, or partial response. Maximum tumor dimension (Dmax), approximate tumor volume (VTumor), and quantitative tumor T2 hyperintensity and contrast enhancement (relative to muscle) for pre- and post-treatment MRIs were compared. RESULTS: Three lesions progressed, 5 lesions were stable, whereas 21 showed a clinical response. Dmax decreased more in responders (mean -11.0 %) than in stable/progressive lesions (mean -3.6 and 0 % respectively, p = 0.28, ANOVA); by Response Evaluation Criteria in Solid Tumors (RECIST 1.1) 27 out of 29 lesions were "stable," including the 3 progressive lesions. In responders, VTumor change averaged -29.4 %, but -19.2 % and +32.5 % in stable and progressive lesions respectively (p = 0.002, ANOVA); by 3D criteria 14 out of 29 lesions showed a partial response. T2 hyperintensity decreased by 50-54 % in partial response/stable disease, but only by 10 % in progressive lesions (p = 0.049, t test). Changes in contrast enhancement ranged from -23 % to 0 %, but were not statistically significant among response groups (p = 0.37). Change in T2 hyperintensity showed a positive correlation with volumetric change (r = 0.40). CONCLUSION: Decreases in volume and T2 hyperintensity reflect the positive response of desmoid fibromatosis to systemic therapy; RECIST 1.1 criteria are not sensitive to clinically determined tumor response.

Key Issues in the Clinical Management of Gastrointestinal Stromal Tumors: An Expert Discussion.

UNLABELLED: After the revelation of kinase targeting with orally available small molecules, the use of imatinib in chronic myelogenous leukemia and in gastrointestinal stromal tumor (GIST) has now become commonplace and just two of many examples of the use of kinase inhibitors in cancer. In this article, we discuss important practice points that may impact upon questions of therapy of primary and metastatic GIST, with the hope that the questions addressed in this rare solid tumor can serve as examples of what can be achieved with kinase-directed therapies in other cancers. We present cases that highlight some of the key issues in GIST management and afterward discuss both points of consensus and controversial issues in what is now recognized as one of the most common forms of sarcoma. IMPLICATIONS FOR PRACTICE: The treatment of gastrointestinal stromal tumor (GIST) has become sophisticated with the availability of three approved agents in many countries and 15 years of experience with primary and metastatic disease. Important lessons from tyrosine-kinase inhibitors in GIST can be gleaned from this experience and will impact implementation of similar agents for other cancers.

The immune system and gastrointestinal stromal tumor: a wealth of opportunities.

PURPOSE OF REVIEW: This article reviews the current literature on tumor-infiltrating immune cells in gastrointestinal stromal tumor (GIST), and the current status and prospects of effective immunotherapeutic strategies. RECENT FINDINGS: Tumor-infiltrating immune cells populate the microenvironment of GISTs; the most numerous are tumor-associated macrophages (TAMs) and CD3 T cells. TAMs have not been shown to have a relationship with the biological behavior of GISTs; however, the number of CD3 T cells correlates with better outcomes. The prognostic significance of tumor-infiltrating neutrophils, natural killer cells, CD4 T cells, CD8 T cells, and Treg cells remains unknown.Imatinib mesylate achieves a clinical response in 80% of patients with GIST. Its antitumor mechanism is partially immune mediated. The combination of imatinib and interferon-α has been shown to be effective against GIST - it eradicates tumor cells including those that are drug resistant. Preclinical trials including cytotoxic T lymphocyte-associated antigen 4 blockade, anti-KIT antibody, and the generation of designer T cells have shown promising therapeutic effect in animal models of GIST. SUMMARY: GIST contains many tumor-infiltrating immune cells and should be susceptible to immunotherapy; early clinical and preclinical trials have shown promising results that should lead to new investigations and effective forms of direct and synergistic therapies.

Rhabdomyosarcoma in adults: new perspectives on therapy.

OPINION STATEMENT: Rhabdomyosarcoma (RMS) is well known as a pediatric disease. Most of the knowledge, like biology, genetics, and treatments of this disease, comes from studies done in that age group. The two subtypes of RMS, embryonic RMS and alveolar RMS, that affect mainly the pediatric population are well described in the literature and that has had an impact on the improvement in overall survival during the past 20 years. RMS in the adult population has a low incidence, therefor the study of RMS in this group is challenging. Pleomorphic RMS is the subtype that mainly affects adults and its biology and genetics are not yet completely understood and described. The risk factors for this tumor and the differences among adults and children is also poorly understood. The treatments for adults that have RMS are not standardized having an impact on the overall survival. Pleomorphic RMS has, compared to other adult sarcomas, poor overall survival. Adult patients with RMS have poor prognosis. The standardization of treatments for the adult population is necessary as maybe new treatments for this specific group. There are new treatment options that are being studied mostly in pediatrics and young adults. Immunotherapy is currently proposed as an important treatment possibility including different techniques like vaccination, antigen-mediated therapy, and immune checkpoints. Even if we have a better understanding of RMS, there are still unanswered questions. The improvements seen in the pediatric population are encouraging, but there is still the need to enhance better therapies for adults with RMS.

Analysis of prognostic factors impacting oncologic outcomes after neoadjuvant tyrosine kinase inhibitor therapy for gastrointestinal stromal tumors.

BACKGROUND: Management of gastrointestinal stromal tumors (GISTs) has been transformed with tyrosine kinase inhibitors (TKIs). While data on optimal duration of adjuvant imatinib remains elusive, guidelines for administration of neoadjuvant TKIs remain unknown. METHODS: Under an institutional review board-approved protocol, patients at our institution with a diagnosis of GIST treated with neoadjuvant TKIs and surgical resection were identified. Clinical and pathologic characteristics were obtained from medical records. RESULTS: Ninety-three patients underwent surgical resection after neoadjuvant TKI therapy; 41 had primary and 52 had recurrent/metastatic GIST. Median follow-up was 2.4 years. Median duration of neoadjuvant therapy was 315 (range 3-1,611) days for primary and 537 (range 4-3,257) days for recurrent/metastatic GIST (p = 0.001). Two-year, recurrence-free survival (RFS) was 85 and 44 % for primary and recurrent/metastatic disease, respectively, whereas 2-year overall survival (OS) was 97 % for primary and 73 % for recurrent/metastatic GIST. For primary GIST, duration of neoadjuvant therapy >365 days (p = 0.02) was associated with higher risk of recurrence on univariate analysis, whereas none of the clinicopathologic factors impacted OS. For recurrent/metastatic disease, disease progression was associated with a shorter OS (p = 0.001), but no factors were found to impact RFS. Lastly, when examining all patients, KIT mutations (p = 0.03) and multivisceral resection (p = 0.011) predicted shorter RFS. CONCLUSIONS: Neoadjuvant TKIs can be effectively used for the treatment of primary and recurrent/metastatic GIST. While duration of neoadjuvant therapy, KIT mutation status, and the need for multivisceral resection can help to predict higher risk for recurrence, progression on neoadjuvant TKIs can aid in selection of patients with recurrent/metastatic disease for surgical resection.

Pazopanib in sarcomas: expanding the PALETTE.

PURPOSE OF REVIEW: After failure of standard therapy, few effective treatment options exist for adult patients with metastatic sarcomas, and median survival remains dismal at approximately 1 year. Pazopanib, a multitargeted tyrosine kinase inhibitor, has recently been approved for nonadipocytic soft tissue sarcomas refractory to chemotherapy. In this review, we will revisit the efficacy of pazopanib in sarcomas, and present a patient case that illustrates two of many unanswered questions: which sarcoma patients are most likely to benefit from pazopanib therapy, and what criteria are best suited to accurately detect benefit in clinical trials? RECENT FINDINGS: Pazopanib has been tested in sarcoma patients in a phase II and phase III study, and was shown to prolong progression-free survival by 3 months relative to placebo. Although histology has been the primary stratification variable for subgroup analysis in large sarcoma trials, the PALETTE study did not demonstrate superior response within histologic cohorts. Ongoing trials seek to explore efficacy of pazopanib in previously excluded histologies, as well as include correlative studies to identify histologic and molecular biomarkers to predict patients likely to benefit. SUMMARY: Pazopanib has been proven to provide modest benefit overall to nonadipocytic soft tissue sarcoma patients, but we have yet to identify the molecular basis for those patients who derive exceptional benefit.

Optimized lentiviral vector transduction of adherent cells and analysis in sulforhodamine B proliferation and chromatin immunoprecipitation assays.

Transduction with lentiviral vectors is a useful approach to study the molecular function of specific genes in mammalian cells. Here, we present a calcium phosphate-based transfection protocol that guarantees highly efficient production and delivery of lentiviral vectors in adherent cultured cells. We also describe in detail a direct lysis technique to measure protein expression, an optimized sulforhodamine B proliferation assay, and a step-by-step chromatin immunoprecipitation procedure to verify the binding of ETV5 to E2F1 first intron in SYO-1 sarcoma cells. For complete details on the use and execution of this protocol, please refer to Kingston et al. (2003),1 Ireton et al. (2002),2 Brown et al. (2009),3 DeSalvo et al. (2021),4 Vichai and Kirtikara (2006),5 and Boyer et al. (2005).6.

MRI T2 mapping assessment of T2 relaxation time in desmoid tumors as a quantitative imaging biomarker of tumor response: preliminary results.

Objectives: Because size-based imaging criteria poorly capture biologic response in desmoid-type fibromatosis (DF), changes in MRI T2 signal intensity are frequently used as a response surrogate, but remain qualitative. We hypothesized that absolute quantification of DF T2 relaxation time derived from parametric T2 maps would be a feasible and effective imaging biomarker of disease activity. Methods: This IRB-approved retrospective study included 11 patients with DF, managed by observation or systemic therapy, assessed by 3T MRI. Tumor maximum diameter, volume, and T2-weighted signal intensity were derived from manual tumor segmentations. Tumor:muscle T2 signal ratios were recorded. Two readers measured tumor T2 relaxation times using a commercial T2 scanning sequence, manual ROI delineation and commercial calculation software enabling estimation of reader reliability. Objective response rates based on RECIST1.1 and best responses were compared between size-based and signal-based parameters. Results: Median patient age was 52.6 years; 8 subjects were female (73%). Nine patients with longitudinal assessments were followed for an average of 314 days. Median baseline tumor diameter was 7.2 cm (range 4.4 - 18.2 cm). Median baseline T2 was 65.1 ms (range 40.4 - 94.8 ms, n=11); median at last follow-up was 44.3 ms (-32% from baseline; range 29.3 - 94.7 ms, n=9). T2 relaxation times correlated with tumor:muscle T2 signal ratios, Spearman p=0.78 (p<0.001). T2 mapping showed high inter-reader reliability, ICC=0.84. The best response as a percentage change in T2 values was statistically significant (mean -17.9%, p=0.05, paired t-test) while change in diameter was not (mean -8.9%, p=0.12). Conclusions: Analysis of T2 relaxation time maps of DF may offer a feasible quantitative biomarker for assessing the extent of response to treatment. This approach may have high inter-reader reliability.

Anti-tumor effects of the Notch pathway in gastrointestinal stromal tumors.

Gastrointestinal stromal tumors (GISTs) are driven by gain-of-function mutations of KIT or PDGFRa. The introduction of imatinib has significantly extended survival for patients. However, most patients develop resistances. Notch signaling is a conserved developmental pathway known to play a critical role in the development of several cancers, functioning as a tumor promoter or a tumor suppressor. Given that the normal progenitor cell for GIST, the interstitial cell of Cajal, has characteristics similar to those of cells of neuroendocrine origin, we hypothesized that Notch pathway impacts the biology of GIST cells. In this study, we retrovirally and pharmacologically manipulated the Notch pathway in human GIST cells. We also performed a retrospective analysis of a cohort on 15 primary tumors to determine the role of Hes1, a major target gene of Notch, as a prognostic marker for GIST. Constitutively, active intracellular domain of Notch1 (ICN1) expression potently induced growth arrest and downregulated KIT expression in vitro. Additionally, treatment with the histone deacetylase inhibitor suberoylanilide hydroxamic acid caused dose-dependent upregulation of Notch1 expression and a parallel decrease in viability in these cells. Retroviral silencing of downstream targets of Notch (dominant-negative Hes1) and pharmacological inhibition of Notch activation (γ-secretase inhibition) partially rescued GIST cells from suberoylanilide hydroxamic acid treatment. GIST patients with high Hes1 mRNA levels have a significantly longer relapse-free survival. These results identify a novel anti-tumor effect of Notch1 and cross talk between the Notch and KIT pathways. Thus, activation of this pathway by treatment with histone deacetylase inhibitors is an appealing potential therapeutic strategy for GISTs. Précis: This study is the first report of the tumor suppressor effects of Notch pathway in gastrointestinal stromal tumors via a negative feedback with the oncogene KIT and may lead the development of new therapeutic strategies for GISTs patients.

Exploiting antitumor immunity to overcome relapse and improve remission duration.

Cancer survivors often relapse due to evolving drug-resistant clones and repopulating tumor stem cells. Our preclinical study demonstrated that terminal cancer patient's lymphocytes can be converted from tolerant bystanders in vivo into effective cytotoxic T-lymphocytes in vitro killing patient's own tumor cells containing drug-resistant clones and tumor stem cells. We designed a clinical trial combining peginterferon α-2b with imatinib for treatment of stage III/IV gastrointestinal stromal tumor (GIST) with the rational that peginterferon α-2b serves as danger signals to promote antitumor immunity while imatinib's effective tumor killing undermines tumor-induced tolerance and supply tumor-specific antigens in vivo without leukopenia, thus allowing for proper dendritic cell and cytotoxic T-lymphocyte differentiation toward Th1 response. Interim analysis of eight patients demonstrated significant induction of IFN-γ-producing-CD8(+), -CD4(+), -NK cell, and IFN-γ-producing-tumor-infiltrating-lymphocytes, signifying significant Th1 response and NK cell activation. After a median follow-up of 3.6 years, complete response (CR) + partial response (PR) = 100%, overall survival = 100%, one patient died of unrelated illness while in remission, six of seven evaluable patients are either in continuing PR/CR (5 patients) or have progression-free survival (PFS, 1 patient) exceeding the upper limit of the 95% confidence level of the genotype-specific-PFS of the phase III imatinib-monotherapy (CALGB150105/SWOGS0033), demonstrating highly promising clinical outcomes. The current trial is closed in preparation for a larger future trial. We conclude that combination of targeted therapy and immunotherapy is safe and induced significant Th1 response and NK cell activation and demonstrated highly promising clinical efficacy in GIST, thus warranting development in other tumor types.

Integrated proteomics and genomics analysis reveals a novel mesenchymal to epithelial reverting transition in leiomyosarcoma through regulation of slug.

Leiomyosarcoma is one of the most common mesenchymal tumors. Proteomics profiling analysis by reverse-phase protein lysate array surprisingly revealed that expression of the epithelial marker E-cadherin (encoded by CDH1) was significantly elevated in a subset of leiomyosarcomas. In contrast, E-cadherin was rarely expressed in the gastrointestinal stromal tumors, another major mesenchymal tumor type. We further sought to 1) validate this finding, 2) determine whether there is a mesenchymal to epithelial reverting transition (MErT) in leiomyosarcoma, and if so 3) elucidate the regulatory mechanism responsible for this MErT. Our data showed that the epithelial cell markers E-cadherin, epithelial membrane antigen, cytokeratin AE1/AE3, and pan-cytokeratin were often detected immunohistochemically in leiomyosarcoma tumor cells on tissue microarray. Interestingly, the E-cadherin protein expression was correlated with better survival in leiomyosarcoma patients. Whole genome microarray was used for transcriptomics analysis, and the epithelial gene expression signature was also associated with better survival. Bioinformatics analysis of transcriptome data showed an inverse correlation between E-cadherin and E-cadherin repressor Slug (SNAI2) expression in leiomyosarcoma, and this inverse correlation was validated on tissue microarray by immunohistochemical staining of E-cadherin and Slug. Knockdown of Slug expression in SK-LMS-1 leiomyosarcoma cells by siRNA significantly increased E-cadherin; decreased the mesenchymal markers vimentin and N-cadherin (encoded by CDH2); and significantly decreased cell proliferation, invasion, and migration. An increase in Slug expression by pCMV6-XL5-Slug transfection decreased E-cadherin and increased vimentin and N-cadherin. Thus, MErT, which is mediated through regulation of Slug, is a clinically significant phenotype in leiomyosarcoma.

The favorable impact of PIK3CA mutations on survival: an analysis of 2587 patients with breast cancer.

The phosphatidylinositol-3 kinase(PI3K) pathway regulates a number of cellular processes, including cell survival, cell growth, and cell cycle progression. Consequently, this pathway is commonly deregulated in cancer. In particular, mutations in the gene PIK3CA that encodes the p110α catalytic subunit of the PI3K enzymes result in cell proliferation and resistance to apoptosis in vitro and induce breast tumors in transgenic mice. These data underscore the role of this pathway during oncogenesis. Thus, an ongoing, large-scale effort is underway to develop clinically active drugs that target elements of the PI3K pathway. However, conflicting data suggest that gain-of-function PIK3CA mutations may be associated with either a favorable or a poor clinical outcome, compared with the wild-type PIK3CA gene. In the current study, we performed a systematic review of breast cancer clinical studies. Upon evaluation of 2587 breast cancer cases from 12 independent studies, we showed that patients with tumors harboring a PIK3CA mutation have a better clinical outcome than those with a wild-type PIK3CA gene. Importantly, this improved prognosis may pertain only to patients with mutations in the kinase domain of p110α and to postmenopausal women with estrogen receptor-positive breast cancer. We propose three potential explanations for this paradoxical observation. First, PIK3CA mutations may interfere with the metastasis process or may induce senescence, which results in a better outcome for patients with mutated tumors. Secondly, we speculate that PIK3CA mutations may increase early tumor diagnosis by modification of the actin cytoskeleton in tumor cells. Lastly, we propose that PIK3CA mutations may be a favorable predictive factor for response to hormonal therapy, giving a therapeutic advantage to these patients. Ultimately, an improved understanding of the clinical impact of PIK3CA mutations is critical for the development of optimally personalized therapeutics against breast cancer and other solid tumors. This effort will be important to prevent or explain therapeutic failures and select patients who are most likely to respond to new therapies that inhibit the PI3K pathway.

IDH1 Mutation Induces HIF-1α and Confers Angiogenic Properties in Chondrosarcoma JJ012 Cells.

Chondrosarcoma is a group of primary bone cancers that arise from transformed cells of chondrocytic lineage. Tumor recurrence and metastasis are devastating for patients with chondrosarcoma since there are no effective treatment options. IDH mutations occur in over 50% of tumors from patients with conventional or dedifferentiated chondrosarcomas and represent an attractive target for therapy. However, their role in the pathogenesis of chondrosarcoma remains largely unknown. In this study, we sought to determine the association of IDH mutation and HIF-1α in chondrosarcoma. We used the chondrosarcoma JJ012 cell line and its derived CRISPR/Cas9 mutant IDH1 (IDH1mut) knockout (KO) cells. RNA-Seq data analysis revealed downregulation of several HIF-1α target genes upon loss of IDH1mut. This was associated with reduced HIF-1α levels in the IDH1mut KO cells and tumors. Loss of IDH1mut also attenuated the expression of angiogenic markers in tumor tissues and abrogated the angiogenic capacity of JJ012 cells. Moreover, we observed that exogenous expression of HIF-1α significantly promoted anchorage-independent colony-formation by IDH1mut KO cells. These results suggest IDH1 mutation confers angiogenic and tumorigenic properties of JJ012 cells by inducing HIF-1α. Thus, the HIF pathway represents a promising candidate for combinatorial regimens to target IDH1 mutated chondrosarcomas.