HMGA1 regulates trabectedin sensitivity in advanced soft-tissue sarcoma (STS): A Spanish Group for Research on Sarcomas (GEIS) study

HMGA1 is a structural epigenetic chromatin factor that has been associated with tumor progression and drug resistance. Here, we reported the prognostic/predictive value of HMGA1 for trabectedin in advanced soft-tissue sarcoma (STS) and the effect of inhibiting HMGA1 or the mTOR downstream pathway in trabectedin activity. The prognostic/predictive value of HMGA1 expression was assessed in a cohort of 301 STS patients at mRNA (n = 133) and protein level (n = 272), by HTG EdgeSeq transcriptomics and immunohistochemistry, respectively. The effect of HMGA1 silencing on trabectedin activity and gene expression profiling was measured in leiomyosarcoma cells. The effect of combining mTOR inhibitors with trabectedin was assessed on cell viability in vitro studies, whereas in vivo studies tested the activity of this combination. HMGA1 mRNA and protein expression were significantly associated with worse progression-free survival of trabectedin and worse overall survival in STS. HMGA1 silencing sensitized leiomyosarcoma cells for trabectedin treatment, reducing the spheroid area and increasing cell death. The downregulation of HGMA1 significantly decreased the enrichment of some specific gene sets, including the PI3K/AKT/mTOR pathway. The inhibition of mTOR, sensitized leiomyosarcoma cultures for trabectedin treatment, increasing cell death. In in vivo studies, the combination of rapamycin with trabectedin downregulated HMGA1 expression and stabilized tumor growth of 3-methylcholantrene-induced sarcoma-like models. HMGA1 is an adverse prognostic factor for trabectedin treatment in advanced STS. HMGA1 silencing increases trabectedin efficacy, in part by modulating the mTOR signaling pathway. Trabectedin plus mTOR inhibitors are active in preclinical models of sarcoma, downregulating HMGA1 expression levels and stabilizing tumor growth.

Efficacy of immune checkpoint inhibitors in alveolar soft-part sarcoma: results from a retrospective worldwide registry

BACKGROUND

Conventional cytotoxic drugs are not effective in alveolar soft-part sarcoma (ASPS). Immune checkpoint (programmed cell death protein 1/programmed death-ligand 1) inhibitors (ICIs) are promising drugs in ASPS. A worldwide registry explored the efficacy of ICI in ASPS.

MATERIALS AND METHODS

Data from adult patients diagnosed with ASPS and treated with ICI for advanced disease in expert sarcoma centers from Europe, Australia and North America were retrospectively collected, including demographics and data related to treatments and outcome.

RESULTS

Seventy-six ASPS patients, with a median age at diagnosis of 25 years (range 3-61 years), were registered. All patients received ICI for metastatic disease. Immunotherapy regimens consisted of monotherapy in 38 patients (50%) and combination in 38 (50%) (23 with a tyrosine kinase inhibitor). Among the 68 assessable patients, there were 3 complete responses and 34 partial responses, translating into an overall response rate of 54.4%. After a median follow-up of 36 months [95% confidence interval (CI) 32-40 months] since the start of immunotherapy, 45 (59%) patients have progressed on ICI, with a median progression-free survival (PFS) of 16.3 months (95% CI 8-25 months). Receiving ICI in first line (P = 0.042) and achieving an objective response (P = 0.043) correlated with a better PFS. Median estimated overall survival (OS) from ICI initiation has not been reached. The 12-month and 24-month OS rates were 94% and 81%, respectively.

CONCLUSIONS

This registry constitutes the largest available series of ASPS treated with ICI. Our results suggest that the ICI treatment provides long-lasting disease control and prolonged OS in patients with advanced ASPS, an ultra-rare entity with limited active therapeutic options.

Genomic Profiling and Clinical Outcomes of Targeted Therapies in Adult Patients with Soft Tissue Sarcomas

Genomic profiling has improved our understanding of the pathogenesis of different cancers and led to the development of several targeted therapies, especially in epithelial tumors. In this review, we focus on the clinical utility of next-generation sequencing (NGS) to inform therapeutics in soft tissue sarcoma (STS). The role of NGS is still controversial in patients with sarcoma, given the low mutational burden and the lack of recurrent targetable alterations in most of the sarcoma histotypes. The clinical impact of genomic profiling in STS has not been investigated prospectively. A limited number of retrospective, mainly single-institution, studies have addressed this issue using various NGS technologies and platforms and a variety of criteria to define a genomic alteration as actionable. Despite the detailed reports on the different gene mutations, fusions, or amplifications that were detected, data on the use and efficacy of targeted treatment are very scarce at present. With the exception of gastrointestinal stromal tumors (GISTs), these targeted therapies are administered either through off-label prescription of an approved drug or enrollment in a matched clinical trial. Based mainly on anecdotal reports, the outcome of targeted therapies in the different STS histotypes is discussed. Prospective studies are warranted to assess whether genomic profiling improves the management of STS patients.

A pan-cancer clinical platform to predict immunotherapy outcomes and prioritize immuno-oncology combinations in early-phase trials

BACKGROUND

Immunotherapy is effective, but current biomarkers for patient selection have proven modest sensitivity. Here, we developed VIGex, an optimized gene signature based on the expression level of 12 genes involved in immune response with RNA sequencing.

METHODS

We implemented VIGex using the nCounter platform (Nanostring) on a large clinical cohort encompassing 909 tumor samples across 45 tumor types. VIGex was developed as a continuous variable, with cutoffs selected to detect three main categories (hot, intermediate-cold and cold) based on the different inflammatory status of the tumor microenvironment.

FINDINGS

Hot tumors had the highest VIGex scores and exhibited an increased abundance of tumor-infiltrating lymphocytes as compared with the intermediate-cold and cold. VIGex scores varied depending on tumor origin and anatomic site of metastases, with liver metastases showing an immunosuppressive tumor microenvironment. The predictive power of VIGex-Hot was observed in a cohort of 98 refractory solid tumor from patients treated in early-phase immunotherapy trials and its clinical performance was confirmed through an extensive metanalysis across 13 clinically annotated gene expression datasets from 877 patients treated with immunotherapy agents. Last, we generated a pan-cancer biomarker platform that integrates VIGex categories with the expression levels of immunotherapy targets under development in early-phase clinical trials.

CONCLUSIONS

Our results support the clinical utility of VIGex as a tool to aid clinicians for patient selection and personalized immunotherapy interventions.

FUNDING

BBVA Foundation; 202-2021 Division of Medical Oncology and Hematology Fellowship award; Princess Margaret Cancer Center.

REGISTRI: Regorafenib in first-line of KIT/PDGFRA wild type metastatic GIST: a collaborative Spanish (GEIS), Italian (ISG) and French Sarcoma Group (FSG) phase II trial

BACKGROUND

Approximately 15% of adult GIST patients harbor tumors that are wild-type for KIT and PDGFRα genes (KP-wtGIST). These tumors usually have SDH deficiencies, exhibit a more indolent behavior and are resistant to imatinib. Underlying oncogenic mechanisms in KP-wtGIST include overexpression of HIF1α high IGFR signaling through the MAPK pathway or BRAF activating mutation, among others. As regorafenib inhibits these signaling pathways, it was hypothesized that it could be more active as upfront therapy in advanced KP-wtGIST.

METHODS

Adult patients with advanced KP-wtGIST after central confirmation by NGS, naïve of systemic treatment for advanced disease, were included in this international phase II trial. Eligible patients received regorafenib 160 mg per day for 21 days every 28 days. The primary endpoint was disease control rate (DCR), according to RECIST 1.1 at 12 weeks by central radiological assessment.

RESULTS

From May 2016 to October 2020, 30 patients were identified as KP-wtGIST by Sanger sequencing and 16 were confirmed by central molecular screening with NGS. Finally, 15 were enrolled and received regorafenib. The study was prematurely closed due to the low accrual worsened by COVID outbreak. The DCR at 12 weeks was 86.7% by central assessment. A subset of 60% experienced some tumor shrinkage, with partial responses and stabilization observed in 13% and 87% respectively, by central assessment. SDH-deficient GIST showed better clinical outcome than other KP-wtGIST.

CONCLUSIONS

Regorafenib activity in KP-wtGIST compares favorably with other tyrosine kinase inhibitors, especially in the SDH-deficient GIST subset and it should be taken into consideration as upfront therapy of advanced KP-wtGIST.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02638766.

Uterine sarcomas: clinical practice guidelines for diagnosis, treatment, and follow-up, by Spanish group for research on sarcomas (GEIS)

Uterine sarcomas are very infrequent and heterogeneous entities. Due to its rarity, pathological diagnosis, surgical management, and systemic treatment are challenging. Treatment decision process in these tumors should be taken in a multidisciplinary tumor board. Available evidence is low and, in many cases, based on case series or clinical trials in which these tumors have been included with other soft tissue sarcoma. In these guidelines, we have tried to summarize the most relevant evidence in the diagnosis, staging, pathological disparities, surgical management, systemic treatment, and follow-up of uterine sarcomas.

A phase II trial of weekly nab-paclitaxel for progressive and symptomatic desmoid tumors

Desmoid fibromatosis (DF) are mesenchymal neoplasms, with potential aggressive course and relevant clinical impact. New systemic therapy modalities are needed in this symptomatic/progressive population. In this multicenter, phase II trial (NCT03275818), patients with symptomatic/progressing DF received three cycles of weekly nab-paclitaxel. Brief pain inventory short form (BPI-SF) was collected at baseline and in every visit. MRI was performed every 3 months. Primary composite endpoint was RECIST 1.1 overall response rate (ORR) and/or clinical response (improvement ≥ 2 points in BPI-SF). If 40% of patients achieved clinical/radiological response, further investigation would be warranted. Toxicity, progression-free survival (PFS), pattern of response and its correlation with clinical best response and BPI, variation of physical function, and analgesic consumption were secondary endpoints. The translational research reported was not a pre-specified secondary outcome. Forty eligible patients started therapy, being 35 radiologically and clinically evaluable. The study achieved its primary endpoint, as 7(20%) patients obtained RECIST partial response, whereas 31(89%) experienced pain reduction of ≥2 points in BPI-SF worst pain. Therapy was well tolerated. With a median follow-up of 30(14-44) months, median 12 and 24-months PFS rates were 91%(CI 95%, 82-100) and 84%(CI 95%, 71-97). For clinical progression, 12 and 24-months PFS rates were 85% (CI 95%, 73-97) and 74% (CI 95%, 58-90) respectively. Short course of nab-paclitaxel is active, safe and achieves quick and durable responses in progressing/symptomatic DF patients.

Phase III assessment of topotecan and cyclophosphamide and high-dose ifosfamide in rEECur: An international randomized controlled trial of chemotherapy for the treatment of recurrent and primary refractory Ewing sarcoma (RR-ES)

LBA2

Background: 5-year survival of RR-ES is about 15%. rEECur, the first randomized controlled trial in this setting, is defining standard care, balancing efficacy and toxicity. Methods: Patients aged 4-50 with RR-ES were randomly assigned to topotecan and cyclophosphamide (TC), irinotecan and temolozomide (IT), gemcitabine and docetaxel (GD), or high-dose ifosfamide (IFOS). Primary outcome was event-free survival (EFS) for the phase III comparison. Secondary outcomes included overall survival (OS), toxicity, and quality of life (QoL). A probability-based Bayesian approach was used with multiple pairwise comparisons. At the first and second interim assessments, patients allocated to GD and IT, respectively, had worse objective response (OR) and EFS than the other arms, halting recruitment to both. The final intent-to-treat assessment of the original four arms was a phase III evaluation of TC and IFOS. Results: 451 patients recruited between 18/12/14 and 31/08/21, were randomly assigned to TC (163 patients), IT (127 patients), GD (72 patients), and IFOS (83 patients). Median age was 19 years (range 4-49). Patients had: refractory disease (18%), first recurrence (66%), > first recurrence (17%). Initial disease site was bone in 70%. Sites of progression were: primary site only (15%), pleuropulmonary metastases only (34%), and other metastatic (51%). Baseline renal function was similar in both. Median follow-up (reverse Kaplan-Meier method) was 40 months. For the phase III comparison between TC and IFOS (both, 73 patients), median EFS was 3.7 months (95% CI, 2.1-6.2) for TC and 5.7 months (95% CI, 3.8-7.0) for IFOS. Median OS was 10.4 months (95% CI, 7.5-15.5) for TC and 16.8 months (95% CI, 11.1-25.8) for IFOS. Given the observed data, the posterior probability that EFS and OS were better after IFOS than after TC (ie Pr [true hazard ratio < 1 | data]) was 95% for both. A greater survival difference was observed for patients aged under 14 than those aged ≥ 14 for EFS and OS. Subgroup analyses favored IFOS for all minimization factors. The main grade 3/4 adverse events (% patients with an event) for TC (left-hand values) compared with IFOS were: febrile neutropenia (26% vs. 25%), infections (8% vs. 14%), vomiting (1% vs. 1%), nausea (0% vs. 3%), diarrhea (1% vs. 1%), encephalopathy (0% vs. 7%), and renal toxicity (0% vs. 8%). Descriptive statistics of quality of life scores appeared to favor the IFOS arm over the TC arm in children but not in adults. Conclusions: The first randomized trial in RR-ES has shown that high-dose ifosfamide is more effective in prolonging survival than TC, having previously beaten GD and IT, and should be considered as a control arm in future randomized phase II/III studies in RR-ES if combination with IFOS is logical. rEECur is the first study to provide comparative toxicity and survival data for the four most commonly used chemotherapy regimens in RR-ES. Clinical trial information: ISRCTN36453794.

A multicenter, dose-finding, phase 1b study of imatinib in combination with alpelisib as third-line treatment in patients with advanced gastrointestinal stromal tumor

BACKGROUND

Acquired resistance to approved tyrosine kinase inhibitors limits their clinical use in patients with gastrointestinal stromal tumor (GIST). This study investigated the safety, tolerability and efficacy of alpelisib, a phosphatidylinositol 3-kinase inhibitor, used in combination with imatinib in patients with advanced GIST who had failed prior therapy with both imatinib and sunitinib.

METHODS

This phase 1b, multicenter, open-label study consisted of 2 phases: dose escalation and dose expansion. Dose escalation involved 200 mg once daily (QD) alpelisib, initially, followed by 250 and 350 mg. These were combined with 400 mg QD imatinib until maximum tolerated dose (MTD) and/or a recommended phase 2 dose (RP2D) of alpelisib in combination with imatinib was determined. This MTD/RP2D dose was tested to evaluate the clinical activity of this combination in dose expansion.

RESULTS

Fifty-six patients were enrolled, 21 and 35 in the dose escalation and expansion phases, respectively. The MTD of alpelisib given with imatinib was determined as 350 mg QD. Combination treatment showed partial response in 1 (2.9%) and stable disease in 15 (42.9%) patients. Median progression-free survival was 2 months (95% CI 1.8-4.6). Overall, 92.9% patients had adverse events (AEs) while 46.4% had grade 3/4 AEs, hyperglycemia being the most common (23.2%).

CONCLUSIONS

The MTD of alpelisib was estimated as 350 mg QD when used in combination with imatinib 400 mg QD after oral administration in patients with advanced GIST. The safety and tolerability profile of this combination was acceptable; however, the combination did not demonstrate sufficient clinical activity to justify additional clinical testing.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01735968 (date of initial registration 28/11/2012).

[Lipoblastoma-like tumor of the vulva: A case report and review of the literature]

Lipoblastoma-like tumor of the vulva (LBLTV) was first described as a benign mesenchymal neoplasia; it was not recognized as a separate diagnosis in the 2013 WHO classification of soft-tissue tumors. To date, only 19 cases have been reported. LBLTV differential diagnosis includes other tumors of the vulvoperineal region and tumors with adipocytic differentiation, most of which are benign and thus a misdiagnosis has few clinical consequences. However, LBLTV may also mimic some aggressive lipomatous neoplasms. We describe a case of LBLTV in a 28 year-old woman and review the literature.

Systemic treatment in advanced phyllodes tumor of the breast: a multi-institutional European retrospective case-series analyses

BACKGROUND

We aimed at investigating outcome of systemic treatments in advanced breast PT.

METHODS

All cases of advanced breast PT treated with systemic treatments from 1999 to 2019, in one of the referral sarcoma centers involved in the study, were retrospectively reviewed.

RESULTS

56 female patients were identified. Median age was 52 (range of 25-76) years. Patients received a median number of 2 systemic treatments (range of 1-4). Best responses according to RECIST were 1 (3.7%) CR, 11 (40.7%) PR, 6 (22.2%) SD, 9 (33.3%) PD with anthracyclines plus ifosfamide (AI); 2 (16.7%) PR, 4 (33.3%) SD, 6 (50.0%) PD with anthracycline alone; 3 (18.8%) PR, 4 (25.0%) SD, 9 (56.3%) PD with high-dose ifosfamide given as a continuous infusion (HD-IFX); 3 (20.0%) SD, 12 (80.0%) PD with a gemcitabine-based regimen (with 2 patients not evaluable); 1 (8.3%) PR, 2 (16.7%) SD, 9 (75.0%) PD with trabectedin (with 1 patient not evaluable); 1 (16.7%) PR, 1 (16.7%) SD, 4 (66.7%) PD with tyrosine-kinase inhibitors (TKI). The median PFS were 5.7 (IQR 2.5-9.1) months with AI; 3.2 (IQR 2.2-5.0) months with anthracycline alone; 3.4 (IQR 1.4-6.7) months with HD-IFX; 2.1 (IQR 1.4-5.2) months with gemcitabine-based chemotherapy; 1.8 (IQR 0.7-6.6) months with trabectedin; 3.4 (IQR 3.1-3.8) months with TKI. With a median follow-up of 35.3 (IQR 17.6-66.9) months, OS from the start of first-line systemic treatment was 15.2 (IQR 7.6-39.6) months.

CONCLUSION

In this series of advanced PT (to our knowledge, the largest reported so far), AI was associated with a high rate of responses, however, with a median PFS of 5.7 months. Other systemic treatments were poorly active.

Predictive Value of MRP-1 in Localized High-Risk Soft Tissue Sarcomas: A Translational Research Associated to ISG-STS 1001 Randomized Phase III Trial

MRP-1 is implicated in multidrug resistance and was described as prognostic in high-risk patients with soft-tissue sarcoma (STS) in a previous study. The current research aimed to validate MRP-1 prognostic/predictive value in localized sarcomas treated with anthracyclines plus ifosfamide within the ISG-1001 phase III study. In addition, the inhibitory activity on MRP-1 was investigated in preclinical studies to identify new combinations able to increase the efficacy of standard chemotherapy in STS. MRP-1 expression was assessed by IHC in tissue microarrays from patients with STS and tested for correlation with disease-free survival (DFS) and overall survival (OS). In vitro studies tested the efficacy of MRP-1 inhibitors (nilotinib, ripretinib, selumetinib, and avapritinib) in sarcoma cell lines. The effect of combinations of the most active MRP-1 inhibitors and chemotherapy was measured on the basis of apoptosis. MRP-1 was evaluable in 231 of 264 cases who entered the study. MRP-1 expression (strong intensity) was independently associated with worse DFS [HR, 1.78; 95% confidence interval (CI), 1.11-2.83; P = 0.016], in the multivariate analysis, with a trend for a worse OS (HR, 1.78; 95% CI, 0.97-3.25; P = 0.062). In vitro studies showed that the addition of MRP-1 inhibitors (nilotinib or avapritinib) to doxorubicin plus palifosfamide, significantly increased cell death in SK-UT-1 and CP0024 cell lines. MRP-1 is an adverse predictive factor in localized high-risk patients with STS treated with neoadjuvant anthracyclines plus ifosfamide followed by surgery. In vitro findings support the clinical assessment of the combination of chemotherapy and MRP-1 inhibitors as a promising strategy to overcome the drug ceiling effect for chemotherapy.

E3 ubiquitin ligase Atrogin-1 mediates adaptive resistance to KIT-targeted inhibition in gastrointestinal stromal tumor

KIT/PDGFRA oncogenic tyrosine kinase signaling is the central oncogenic event in most gastrointestinal stromal tumors (GIST), which are human malignant mesenchymal neoplasms that often feature myogenic differentiation. Although targeted inhibition of KIT/PDGFRA provides substantial clinical benefit, GIST cells adapt to KIT/PDGFRA driver suppression and eventually develop resistance. The specific molecular events leading to adaptive resistance in GIST remain unclear. By using clinically representative in vitro and in vivo GIST models and GIST patients' samples, we found that the E3 ubiquitin ligase Atrogin-1 (FBXO32)-the main effector of muscular atrophy in cachexia-resulted in the most critical gene derepressed in response to KIT inhibition, regardless the type of KIT primary or secondary mutation. Atrogin-1 in GISTs is transcriptionally controlled by the KIT-FOXO3a axis, thus indicating overlap with Atrogin-1 regulation mechanisms in nonneoplastic muscle cells. Further, Atrogin-1 overexpression was a GIST-cell-specific pro-survival mechanism that enabled the adaptation to KIT-targeted inhibition by apoptosis evasion through cell quiescence. Buttressed on these findings, we established in vitro and in vivo the preclinical proof-of-concept for co-targeting KIT and the ubiquitin pathway to maximize the therapeutic response to first-line imatinib treatment.

Retrospective world-wide registry on the efficacy of immune checkpoint inhibitors in alveolar soft part sarcoma: Updated results from sixty patients

11564

Background: Alveolar soft-part sarcoma (ASPS) is a highly metastasizing ultra-rare sarcoma subtype, frequently affecting young adults. Conventional cytotoxic drugs are not effective in ASPS, but antiangiogenics demonstrated significant improvement in tumor burden reduction and PFS in the only ever conducted comparative trial. Immune check-point (PD-1/PD-L1) inhibitors (ICI) are emerging promising drugs in the therapy of ASPS, from small reported retrospective and prospective series. A world-wide registry has been set up with the aim of exploring the efficacy of ICI in ASPS. Methods: Data from adult patients (pts) diagnosed with ASPS and treated with PD- 1/PD-L1 inhibitors for advanced disease in expert sarcoma centers from Europe, Australia and US was retrospectively collected. IRB approval was obtained. Demographics, data related to treatments and outcome were considered. Radiologic assessment was based on RECIST 1.1. Progression-free (PFS) and overall survival (OS) were calculated with Kaplan-Meier method. An updated analysis of this series is presented here. Results: Sixty ASPS pts (27 female/33 male) with a median age at diagnosis of 25y (range 3-61) were registered. Primary tumor arose in limbs in 47 pts (78%) and 41 pts (68%) were metastatic at diagnosis. 52/60 pts (87%) had received previous systemic therapy (including chemotherapy in 19 pts and antiangiogenics in 47pts), with a median of one previous line (0-6). All pts received ICI for metastatic disease. Immunotherapy regimens consisted of monotherapy in 31 pts (52%) and combination in 29 pts (48%) (23 with an antiangiogenic agent). 29/60 pts (48%) received ICI within a clinical trial. Among the 52 evaluable pts, there was 1 complete response (CR) and 20 partial responses (PR) (ORR 40.4%). After a median follow-up of 21 months -mos- (range 4-59), 37/60 pts have progressed to ICI, with a median PFS of 13.4 mos (95% CI 10.1-16.7). Eleven pts received a subsequent line of ICI with a median PFS of 26 mos (95%CI 0-57). 16 pts have died, being the median OS from ICI initiation 38 mos (95% CI 33-43). The 12-mos and 24-mos OS rates were 94% and 70% respectively. Conclusions: This registry constitutes the largest available series of ASPS treated with immune check-point inhibitors. Our results suggest that treatment with ICI provide long-lasting disease control and prolonged OS in pts with advanced ASPS, an ultra-rare entity with limited active therapeutic options. The results on subsequent ICI lines suggest a lack of cross-resistance among different ICI therapies.

A phase Ib/II study of selinexor in combination with imatinib in patients with advanced gastrointestinal stromal tumor (GIST): SeliGIST/GEIS-41 trial

11534

Background: KIT or PDGFRA oncogenic activation drives GIST progression throughout the disease course. Accordingly, currently approved agents in metastatic GIST focus on the therapeutic suppression of these receptors. However, the clinical benefit after imatinib (IM) progression is still modest, suggesting the co-operation of KIT/PDGFRA-independent mechanisms in GIST cell survival. Selinexor is an oral, selective inhibitor of XPO1-mediated nuclear export, and preclinical studies evidenced antitumoral activity in GIST as single agent and in combination with IM in both IM-sensitive and IM-resistant models. Methods: The phase Ib portion studied IM 400 mg daily plus weekly selinexor in patients (pts) with IM-resistant, advanced GIST. Prior intolerance to IM was not allowed. A standard 3+3 dosing schema was utilized to determine the recommended phase II dose (RP2D) of this combination. Investigator-assessed response was evaluated every 8 weeks using RECIST 1.1. Results: At data cutoff of Sep 25, 2020, 12 pts were enrolled and received treatment with IM 400 mg and selinexor once weekly at dose levels (DL) 1 (60 mg), DL2 (80 mg) and DL3 (100 mg). Median age 57 (range 46-77), 42% female, median prior therapies 4 (range 2-7). Although only 1/6 pts developed a dose limiting toxicity (DLT) at DL3, the RP2D was defined at DL2 (IM 400 mg daily and selinexor 80 mg once weekly) based on activity data in the DL2 and the need for dose reductions in 5/6 pts at DL3 after the DLT window. All pts were evaluable for toxicity and response. One DLT occurred at DL3 (G3 nausea). Non-DLT G3/4 toxicities were anemia (1/12 pts), neutropenia (1/12 pts), vomiting (1/12 pts) and fatigue (2/12 pts). Common G1/2 toxicities were nausea (11/12 pts), vomiting (10/12 pts), neutropenia (5/12 pts) and anemia, fatigue, diarrhea, and periorbital edema (4/12 pts each). No unexpected toxicities were observed. Overall response rate in the 12 pts evaluable for response was 67% (95% CI 0.349-0.901), with 2 pts achieving PR (17%) and 6 pts SD (50%) as the best response. Clinical benefit rate (CBR = CR, PR, SD) ≥ 16 weeks was 42% (95% CI 0.157-0.723). Median progression free survival was 3.5 months (95% CI 1.7-7.3). Four pts remain on trial at data cutoff. Conclusions: IM and selinexor combination is well-tolerated and has clinical activity in heavily pretreated GIST pts. The trial is currently exploring selinexor as single agent in the IM-resistant GIST population. Clinical trial information: NCT04138381.

A DNA damage repair gene-associated signature predicts responses of patients with advanced soft-tissue sarcoma to treatment with trabectedin

Predictive biomarkers of trabectedin represent an unmet need in advanced soft‐tissue sarcomas (STS). DNA damage repair (DDR) genes, involved in homologous recombination or nucleotide excision repair, had been previously described as biomarkers of trabectedin resistance or sensitivity, respectively. The majority of these studies only focused on specific factors (ERCC1, ERCC5, and BRCA1) and did not evaluate several other DDR‐related genes that could have a relevant role for trabectedin efficacy. In this retrospective translational study, 118 genes involved in DDR were evaluated to determine, by transcriptomics, a predictive gene signature of trabectedin efficacy. A six‐gene predictive signature of trabectedin efficacy was built in a series of 139 tumor samples from patients with advanced STS. Patients in the high‐risk gene signature group showed a significantly worse progression‐free survival compared with patients in the low‐risk group (2.1 vs 6.0 months, respectively). Differential gene expression analysis defined new potential predictive biomarkers of trabectedin sensitivity (PARP3 and CCNH) or resistance (DNAJB11 and PARP1). Our study identified a new gene signature that significantly predicts patients with higher probability to respond to treatment with trabectedin. Targeting some genes of this signature emerges as a potential strategy to enhance trabectedin efficacy.

Cocaine-induced Fos expression in the rat brain: Modulation by prior Δ9-tetrahydrocannabinol exposure during adolescence and sex-specific effects

It has been suggested that cannabis consumption during adolescence may be an initial step to cocaine use in adulthood. Indeed, previous preclinical data show that adolescent exposure to cannabinoids (both natural and synthetic) potentiates cocaine self-administration in rats. Here we aimed at gaining a deeper understanding of the cellular activation patterns induced by cocaine as revealed by Fos imaging and how these patterns may change due to adolescent exposure to THC. Male and female Wistar rats were administered every other day THC (3 mg/kg i.p.) or vehicle from postnatal day 28-44. At adulthood (PND90) they were given an injection of cocaine (20 mg/kg i.p.) or saline and sacrificed 90 min later. Cocaine-induced Fos activation was measured by immunohistochemistry as an index of cellular activation. We found that cocaine-induced activation in the motor cortex was stronger in THC-exposed rats. Moreover, there was significant sex-dependent interaction between cocaine and adolescent THC exposure in the dorsal hypothalamus, suggesting that cocaine induced a more robust cellular activation in THC-exposed females but not in THC-treated males. Other THC- and cocaine-induced effects were also evident. These results add to the previous literature suggesting that the behavioral, cellular, molecular, and brain-activating actions of cocaine are modulated by early experience with cannabinoids and provide additional knowledge that may explain the enhanced actions of cocaine in rats exposed to cannabinoids during their adolescence.

Ripretinib in gastrointestinal stromal tumor: the long-awaited step forward

Gastrointestinal stromal tumor (GIST) represents a paradigm for clinically effective targeted inhibition of oncogenic driver mutations in cancer. Five drugs are currently positioned as the standard of care for the treatment of advanced or metastatic GIST patients. This is the result of continuous, deep understanding of KIT and PDGFRA GIST oncogenic drivers as well as the resistance mechanisms associated to tumor progression. However, the complexity of GIST molecular heterogeneity is an evolving field, and critical questions remain open. Specifically, the clinical benefit of approved and/or investigated targeted agents is strikingly modest at advanced stages of the disease when compared with the activity of first-line imatinib. Ripretinib is a novel switch-pocket inhibitor with broad activity against KIT and PDGFRA oncoproteins and has recently demonstrated antitumoral activity across phase I to phase III clinical trials. Therefore, ripretinib has emerged as a new standard of care for advanced, multi-resistant GIST patients. Based on this data, the Food and Drug Administration has granted in 2020 the approval of ripretinib for GIST patients after progression to imatinib, sunitinib and regorafenib. This, in turn, constitutes a major breakthrough in sarcoma drug development, as there have not been new treatment approvals in GIST for nearly a decade. Herein, we provide a critical review on the preclinical and clinical development of ripretinib in GIST. Furthermore, we seek to assess the biological and clinical impact of this new standard of care on the course of the disease, aiming to provide an insight on future treatments strategies for the next coming years.

Nivolumab and sunitinib combination in advanced soft tissue sarcomas: a multicenter, single-arm, phase Ib/II trial

BACKGROUND

Sarcomas exhibit low expression of factors related to immune response, which could explain the modest activity of PD-1 inhibitors. A potential strategy to convert a cold into an inflamed microenvironment lies on a combination therapy. As tumor angiogenesis promotes immunosuppression, we designed a phase Ib/II trial to test the double inhibition of angiogenesis (sunitinib) and PD-1/PD-L1 axis (nivolumab).

METHODS

This single-arm, phase Ib/II trial enrolled adult patients with selected subtypes of sarcoma. Phase Ib established two dose levels: level 0 with sunitinib 37.5 mg daily from day 1, plus nivolumab 3 mg/kg intravenously on day 15, and then every 2 weeks; and level -1 with sunitinib 37.5 mg on the first 14 days (induction) and then 25 mg per day plus nivolumab on the same schedule. The primary endpoint was to determine the recommended dose for phase II (phase I) and the 6-month progression-free survival rate, according to Response Evaluation Criteria in Solid Tumors 1.1 (phase II).

RESULTS

From May 2017 to April 2019, 68 patients were enrolled: 16 in phase Ib and 52 in phase II. The recommended dose of sunitinib for phase II was 37.5 mg as induction and then 25 mg in combination with nivolumab. After a median follow-up of 17 months (4-26), the 6-month progression-free survival rate was 48% (95% CI 41% to 55%). The most common grade 3-4 adverse events included transaminitis (17.3%) and neutropenia (11.5%).

CONCLUSIONS

Sunitinib plus nivolumab is an active scheme with manageable toxicity in the treatment of selected patients with advanced soft tissue sarcoma, with almost half of patients free of progression at 6 months.Trial registration number NCT03277924.

Diagnosis and management of tropomyosin receptor kinase (TRK) fusion sarcomas: expert recommendations from the World Sarcoma Network

Sarcomas are a heterogeneous group of malignancies with mesenchymal lineage differentiation. The discovery of neurotrophic tyrosine receptor kinase (NTRK) gene fusions as tissue-agnostic oncogenic drivers has led to new personalized therapies for a subset of patients with sarcoma in the form of tropomyosin receptor kinase (TRK) inhibitors. NTRK gene rearrangements and fusion transcripts can be detected with different molecular pathology techniques, while TRK protein expression can be demonstrated with immunohistochemistry. The rarity and diagnostic complexity of NTRK gene fusions raise a number of questions and challenges for clinicians. To address these challenges, the World Sarcoma Network convened two meetings of expert adult oncologists and pathologists and subsequently developed this article to provide practical guidance on the management of patients with sarcoma harboring NTRK gene fusions. We propose a diagnostic strategy that considers disease stage and histologic and molecular subtypes to facilitate routine testing for TRK expression and subsequent testing for NTRK gene fusions.

A randomized double-blind phase II study evaluating the role of maintenance therapy with cabozantinib in high-grade uterine sarcoma after stabilization or response to doxorubicin ± ifosfamide following surgery or in metastatic first line treatment (EORTC62113)

BACKGROUND

Uterine sarcomas are a group of rare tumors that include different subtypes. Patients with histopathological high-grade diseases are at high-risk of recurrence or progression, and have a poor prognosis. We aim to explore the most appropriate management in patients with uterine high-grade sarcomas.

PRIMARY OBJECTIVE

To assess the efficacy of maintenance treatment with cabozantinib in patients with high-grade uterine sarcomas who achieved clinical benefit after standard chemotherapy.

STUDY HYPOTHESIS

Maintenance treatment with cabozantinib after standard chemotherapy given as an adjuvant treatment after curative surgery, or in locally advanced or metastatic disease, increases progression-free survival compared with placebo TRIAL DESIGN: This is a randomized double blinded phase II trial.

MAJOR INCLUSION/EXCLUSION CRITERIA

The study is enrolling adult patients with high-grade undifferentiated uterine sarcomas, high-grade endometrial stromal sarcomas, high-grade leiomyosarcoma, and high-grade adenosarcoma, FIGO (Federation International gynecologue Obstétricien) stage II/III to IV in stable disease or who achieved complete or partial response with doxorubicin ± ifosfamide, who are assigned 1:1 to 60 mg daily cabozantinib (experimental arm) or placebo (control arm), as maintenance therapy. Exclusion criteria include low-grade sarcoma.

PRIMARY ENDPOINT

Progression-free survival at 4 months.

SAMPLE SIZE

The study plans to enroll 90 patients to allow the randomization of 54 patients to detect an improvement in 4-month progression-free survival from 50% to 80% with 15% significance level and 85% power. Estimated dates for accrual completion: recruitment for the trial started in February 2015, and has currently enrolled 83 patients, of whom 35 patients have been randomized. The end of recruitment is anticipated for December 2020.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov, number NCT01979393.

Abstract 3767: FBXO32 ubiquitin ligase mediates apoptosis evasion and adaptation to KIT inhibition in gastrointestinal stromal tumor - GIST

Introduction: GIST is the most common malignant mesenchymal neoplasm and features myogenic differentiation. Most GISTs depend upon oncogenic signaling through constitutively activated forms of KIT and exhibit remarkable responses to the first-line KIT inhibitor imatinib. Secondary resistance involves emergence of subclonal populations harboring heterogeneous KIT-secondary mutations that are not collectively inhibited by any approved therapy. We dissected KIT-downstream signaling nodes to identify mediators of the KIT oncogenic program, seeking targets of overarching relevance in polyclonal imatinib-resistant GIST.

Methods: using clinically-representative human GIST cell models, we undertook pharmacological and functional screening to identify key targetable nodes within KIT-downstream PI3K/mTOR and RAS/MAPK pathways and to model therapeutic strategies in vitro and in vivo. Transcriptomic analysis (RNAseq) identified genes co-regulated by PI3K/mTOR and RAS/MAPK, and functional evaluations by lentiviral construct overexpression and gene knockdown elucidated roles in GIST biology.

Results: PI3K/mTOR and MEK1/2 were the most essential KIT-dependent nodes irrespective of the type of KIT primary or secondary mutation. Single node ablation did not yield sustained antiproliferative and apoptotic effects, but concurrent intermittent inhibition was synergistic in vitro and in vivo, supporting the critical and complementary roles of these two pathways. Transcriptomic analyses underscored FBXO32 (a SCF E3 ubiquitin ligase and the main effector of muscular atrophy) as the most differentially expressed gene co-regulated by the PI3K/mTOR and RAS/MAPK pathways. FBXO32 was also the most differentially expressed gene after KIT inhibition in GIST cell lines, and enrichment in FBXO32 expression was found in post-imatinib GIST samples compared to baseline matched tumor tissue. We demonstrated that FBXO32 is transcriptionally upregulated by FOXO3a upon KIT or concurrent PI3K/mTOR and MEK1/2 blockage, paralleling human muscle regulation. Notoriously, FBXO32 proved to have a pro-survival role in GIST cells, enabling evasion of apoptosis. Microarray and in vitro and in vivo functional assays showed that FBXO32 mediates cell cycle exit and quiescence upon KIT or concurrent KIT-downstream pathways inhibition, thereby minimizing imatinib-induced apoptosis and facilitating GIST cell survival.

Conclusions: PI3K/mTOR and MEK1/2 are critical mediators of KIT oncogenic signaling in GIST. FBXO32 emerges as a KIT-dependent E3 ubiquitin ligase transcriptionally repressed through KIT downstream pathways. However, FBXO32 induction upon therapeutic KIT signaling inhibition triggers quiescence and subsequent apoptosis evasion, thus emerging as a novel mechanism of adaptation to therapeutic inhibition of oncogenic KIT.

Citation Format: Alfonso García Valverde, Jordi Rosell, Daniel Pilco Janeta, Sergi Sayols, Claudia Valverde, Anna Esteve, Marta Gut, Jordi Barretina, George D. Demetri, Jonathan A. Fletcher, Joan Carles, Joaquín Arribas, César Serrano. FBXO32 ubiquitin ligase mediates apoptosis evasion and adaptation to KIT inhibition in gastrointestinal stromal tumor - GIST [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3767.

Synthesis and structural studies on (E)-3-(2,6-difluorophenyl)-1-(4-fluorophenyl)prop-2-en-1-one: a promising nonlinear optical material

A new fluorinated chalcone (E)-3-(2,6-difluorophenyl)-1-(4-fluorophenyl)prop-2-en-1-one was synthesized in 90% yield and crystallized by a slow evaporation technique. Its full structural characterization and purity were determined by scanning electron microscopy, infrared spectroscopy, gas chromatography-mass spectrometry, 1H, 13C and 19F nuclear magnetic resonance, thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), Raman microspectroscopy, UV-Vis absorption spectroscopy, single crystal X-ray diffraction (XRD) and Hirshfeld surface (HS) analysis. The fluorinated chalcone crystallized in centrosymmetric space group P21/c stabilized by the C-H⋯O and C-H⋯F interactions and the π⋯π contact. The crystalline environment was simulated through the supermolecule approach where a bulk with 378 000 atoms was built. The electric parameters were calculated at the DFT/CAM-B3LYP/6-311++G(d,p) level as function of the electric field frequency. The macroscopic parameters such as linear refractive index and third-order nonlinear susceptibility (χ (3)) were calculated, and the results were compared with experimental data obtained from the literature. The χ (3)-value for the chalcone crystal is 369.294 × 10-22 m2 V-2, higher than those obtained from a few similar types of molecule, showing that the chalcone crystal can be considered as a nonlinear optical material. Also, molecular theoretical calculations such as infrared spectrum assignments, frontier molecular orbital analysis and MEP were implemented, revealing that the most positive region is around the hydrogen atoms of the aromatic rings, and electrophilic attack occurs on the carbonyl group.

SPEARHEAD-1: A phase II trial of ADP-A2M4 SPEAR T cells in patients with advanced synovial sarcoma or myxoid/round cell liposarcoma

TPS11569

Background: ADP-A2M4 specific peptide enhanced affinity receptor (SPEAR) T-cells are genetically engineered to target MAGE-A4+ tumors in the context of HLA-A*02. MAGE-A4 has been described as having high expression in synovial sarcoma (SS) and myxoid/round cell liposarcoma (MRCLS) [1, 2]. This Phase 2 trial was initiated based on the favorable benefit:risk profile of ADP-A2M4 observed in a Phase 1 trial (NCT03132922) of ADP-A2M4 which demonstrated compelling clinical responses in patients with SS. Methods: This Phase 2, open-label trial (SPEARHEAD-1; NCT04044768) is designed to evaluate the efficacy, safety and tolerability of ADP-A2M4 in patients with advanced/metastatic SS or MRCLS who are HLA-A*02 positive and whose tumors express the MAGE-A4 protein. Enrolled patients are to undergo apheresis, and their isolated T-cells are then transduced with the MAGE-A4c1032 TCR, and expanded. Prior to ADP-A2M4 infusion, patients are to receive lymphodepleting chemotherapy consisting of fludarabine (30 mg/m2/day x 4 days) and cyclophosphamide (600 mg/m2/day x 3 days). Patients are to receive 1 – 10 × 109 transduced T-cells. An independent Data Safety Monitoring Board will review ongoing safety and benefit:risk during the interventional phase of the study. Disease will be assessed by independent review per RECIST v1.1 by CT/MRI at weeks 4, 8, 12, 16, 24, and every 2 months thereafter until confirmed disease progression. As of 24 Jan 2020, there were 17 clinical sites open in the US, one in Canada, and two in Spain. References: 1. Iura K, et al. Cancer-testis antigen expression in synovial sarcoma: NY-ESO-1, PRAME, MAGEA4, and MAGEA1. Human Pathology 2017; 61:130-139. 2. Iura K, et al. MAGEA4 expression in bone and soft tissue tumors: its utility as a target for immunotherapy and diagnostic marker combined with NY-ESO-1. Virchows Archiv 2017;471:383–392. Clinical trial information: NCT04044768 .

Preclinical Activity of PI3K Inhibitor Copanlisib in Gastrointestinal Stromal Tumor

KIT or PDGFRA gain-of-function mutations are the primary drivers of gastrointestinal stromal tumor (GIST) growth and progression throughout the disease course. The PI3K/mTOR pathway is critically involved in the transduction of KIT/PDGFRA oncogenic signaling regardless of the type of primary and secondary mutations, and therefore emerges as a relevant targetable node in GIST biology. We evaluated in GIST preclinical models the antitumor activity of copanlisib, a novel pan-class-I PI3K inhibitor with predominant activity against p110α and p110δ isoforms, as single-agent and in combination with first-line KIT inhibitor imatinib. In vitro studies undertaken in one imatinib-sensitive (GIST-T1) and two imatinib-resistant (GIST-T1/670 and GIST430/654) GIST cell models showed that single-agent copanlisib effectively suppressed PI3K pathway activation leading to decreased cell viability and proliferation in both imatinib-sensitive and -resistant cells irrespective of the type of primary or secondary KIT mutations. Simultaneous PI3K and KIT inhibition with copanlisib and imatinib resulted in enhanced impairment of cell viability in both imatinib-sensitive and -resistant GIST cell models, although apoptosis was mostly triggered in GIST-T1. Single-agent copanlisib inhibited GIST growth in vivo, and conjoined inhibition of PI3K and KIT was the most active therapeutic intervention in imatinib-sensitive GIST-T1 xenografts. IHC stain for cleaved-caspase 3 and phospho-S6 support a predominant antiproliferative effect of copanlisib in GIST. In conclusion, copanlisib has single-agent antitumor activity in GIST regardless KIT mutational status or sensitivity to imatinib. Effective KIT inhibition is necessary to achieve synergistic or additive effects with the combination of imatinib and any given PI3K/mTOR pathway inhibition.

The future of bladder cancer therapy: Optimizing the inhibition of the fibroblast growth factor receptor

Therapeutic options for metastatic bladder cancer (BC) have seen minimal evolution over the past 30 years, with platinum-based chemotherapy remaining the mainstay of standard of care for metastatic BC. Recently, five immune checkpoint inhibitors (ICIs) have been approved by the FDA as second-line therapy, and two ICIs are approved as first-line treatment in selected patients. Molecular alterations of muscle-invasive bladder cancer (MIBC) have been reported by The Cancer Genome Atlas. About 15% of patients with MIBC have molecular alterations in the fibroblast growth factor (FGF) axis. Several ongoing trials are testing novel FGF receptor (FGFR) inhibitors in patients with FGFR genomic aberrations. Recently, erdafitinib, a pan-FGFR inhibitor, was approved by the FDA in patients with metastatic BC who have progressed on platinum-based chemotherapy. We reviewed the literature over the last decade and provide a summary of current knowledge of FGF signaling, and the prognosis associated with FGFR mutations in BC. We cover the role of FGFR inhibition with non-selective and selective tyrosine kinase inhibitors as well as novel agents in metastatic BC. Efficacy and safety data including insights from mechanism-based toxicity are reported for selected populations of metastatic BC with FGFR aberrations. Current strategies to managing resistance to anti-FGFR agents is addressed, and the importance of developing reliable biomarkers as the therapeutic landscape moves towards an individualized therapeutic approach.

Clinical value of next generation sequencing of plasma cell-free DNA in gastrointestinal stromal tumors

Background

Gastrointestinal stromal tumor (GIST) initiation and evolution is commonly framed by KIT/PDGFRA oncogenic activation, and in later stages by the polyclonal expansion of resistant subpopulations harboring KIT secondary mutations after the onset of imatinib resistance. Thus, circulating tumor (ct)DNA determination is expected to be an informative non-invasive dynamic biomarker in GIST patients.

Methods

We performed amplicon-based next-generation sequencing (NGS) across 60 clinically relevant genes in 37 plasma samples from 18 GIST patients collected prospectively. ctDNA alterations were compared with NGS of matched tumor tissue samples (obtained either simultaneously or at the time of diagnosis) and cross-validated with droplet digital PCR (ddPCR).

Results

We were able to identify cfDNA mutations in five out of 18 patients had detectable in at least one timepoint. Overall, NGS sensitivity for detection of cell-free (cf)DNA mutations in plasma was 28.6%, showing high concordance with ddPCR confirmation. We found that GIST had relatively low ctDNA shedding, and mutations were at low allele frequencies. ctDNA was detected only in GIST patients with advanced disease after imatinib failure, predicting tumor dynamics in serial monitoring. KIT secondary mutations were the only mechanism of resistance found across 10 imatinib-resistant GIST patients progressing to sunitinib or regorafenib.

Conclusions

ctDNA evaluation with amplicon-based NGS detects KIT primary and secondary mutations in metastatic GIST patients, particularly after imatinib progression. GIST exhibits low ctDNA shedding, but ctDNA monitoring, when positive, reflects tumor dynamics.

Impact of immune-related adverse events on survival in patients with metastastic urothelial carcinoma treated with immune-checkpoint inhibitors

4531

Background: Immune-checkpoints inhibitors (ICIs) represents the standard of care for platinum-pretreated advanced urothelial cancer patients (pts). By enhancing T-cell activation, a unique spectrum of inflammatory side effects has emerged, also known as immune-related adverse events (irAEs). Data regarding the association between irAEs and pts outcomes are conflicting. Here we conducted a retrospective analysis to investigate the association between irAEs profile and disease outcome in metastastic urothelial carcinoma (mUC) pts. Methods: Medical records from pts with mUC included in clinical trials between July 2013 and June 2018 and treated with ICIs were reviewed. Pts previously treated with platinum-based chemotherapy or cisplatin ineligible pts who had not been previously treated with chemotherapy were included. Clinical responses were assessed as complete response (CR), partial response (PR), stable disease (SD), and progressive disease (PD) according to RECIST v1.1. Adverse events were graded based CTCAE v4.03. Overall survival (OS) was calculated from the date of initiation of ICI to the date of death. X2 test was used to determine differences in rates. OS was estimated using Kaplan-Method and long rank test was used to assess differences between groups. All analyses were performed using SPSS v21. Results: From a total of 52 pts, 44 (84.6%) were treated with ICI monotherapy and 8 (15.3%) in combination (anti-CTLA4 or targeted therapy). Median age was 65 years, 42 pts (80.8%) were male, 44 patients (84.6%) had ECOG PS 0-1, 14 pts (26.9%) had liver metastasis. Overall irAEs were observed in 30 pts (57.7%) and 10 pts (19.2%) developed grade 3/4 irAES. Most common grade 3/4 irAEs were diarrhea (6.6%), rash (6.6%) and hepatitis (6.6%). Disease control rate (CR [26%]+PR[33%]+SD[20%]) was higher for patients with irAEs compared to those patients who did not developed irAEs (CR [13.6%]+PR[0%]+SD[22.7%], this difference was statically significant (P = 0.002). Median OS was 11.23 mo (CI 95%, 3.76-18.70) for the overall cohort, while median OS was 21.91 mo for those patients with irAEs compared to 6.47 mo in patients who did not developed irAEs (P = 0.004). Conclusions: In this analysis we found that the development of irAEs was a strong predictor of improved OS in mUC patients treated with ICI.

Interim analysis of a phase II study of nivolumab combined with ipilimumab in patients with pediatric solid tumors in adulthood (GETHI021)

2613

Background: Solid pediatric tumors that appear in adulthood are a heterogeneous group characterized by a low incidence, lack of standard therapeutic options and reduced survival. We have designed the first phase II clinical trial of nivolumab and ipilimumab in this setting, Here, we present the results of the first cohort with 30 evaluable patients. Methods: This is a multicenter, open-label, single arm Phase II study conducted in 15 centers of the Spanish Group for Rare Cancer (GETHI). We aimed to evaluate efficacy and safety of the combination of nivolumab and ipilimumab in adult patients ( 18 years) with locally advanced or metastatic childhood malignancies that have progressed or are not candidates to standard therapy. Treatment consisted on nivolumab 3 mg/kg IV q2w + ipilimumab 1 mg/kg IV q6w for 6 months or until progression/unacceptable toxicity, for a maximum of 24 months. Primary endpoint was overall response rate (ORR) according to RECIST v1.1 criteria. We used a Simon optimal two-stage design, with a first stage including first 30 evaluable patients. Results: 20 patients were male and median age was 43 (range 20-75). Most frequent histologies were medulloblastoma (4) neuroblastoma (4) and Ewing family tumors (3). 90% had received prior systemic therapy with 37% presenting progressive disease as best response. Median previous treatment lines were 3 (range 1-9). 27 patients were PS0-1, and 3 PS2. 6 patients have been treated for ≥6 months . Only one discontinued for adverse events. With a median follow up of 4,3 months (range 0,4-11,3), 1 patient has achieved a deep partial response (PR) (3,6%), 10 stable disease (SD) (35,7%) and 17 progressive disease (PD) (60,7%). 2 patients died before radiologic evaluation. Clinical benefit rate (CR+PR+SD) was 39,3%. Median progression free survival (PFS) was 1,8 months (95% CI 1,3-2,3), with a 3-months-PFS of 32,7% and 6-months-PFS of 20%. Median overall survival (OS) was 6,8 months (95% CI 3,3-10,2). 12 (40%) patients presented adverse events (AE) of any grade and 6 (20%) experienced a grade AE deemed as possibly related to treatment. Conclusions: The combination of nivolumab and ipilimumab showed significant clinical benefit in this population with little therapeutic options. One case of metastatic esthesioneuroblastoma, achieved a dramatic tumor response and represents the first patient with this extremely rare histology treated with immunotherapy. Clinical trial information: EudraCT 2016-003946-99.

Hyperprogressive disease in patients with metastatic genitourinary tumors treated with immune checkpoint inhibitors

448

Background: Hyperprogressive disease (HPD) is a new pattern of progression in cancer patients (pts) treated with immune checkpoint inhibitors (ICI). The rate and outcome of HDP in pts with metastatic renal carcinoma (RCC) and urothelial carcinoma (UC) are unknown. Here, we report the percentage of HPD in a cohort of pts with GU malignancies treated at our center and explore associations with clinical variables. Methods: Medical records from pts treated in phase I-III clinical trials with ICI alone or in combination between July 2013 and June 2018 were retrospectively reviewed. We defined HPD according to the radiologic VHIO´s criteria (ASCO 2018). Associations between HPD and categorical or continuous variables were evaluated using Fisher exact test and Wilcoxon test respectively. OS were estimated with the Kaplan-Meir method. Statistical analyses were performed using the R statistical software (R version 3.5.0). Results: Overall, 104 pts received therapy with ICI. Of these patients, 16 were not included for the analysis (6 pts with absence of measurable disease, 6 pts did not have CT scan available after the clinical progression and 4 pts treated with ICI plus chemotherapy). Thus, 88 pts were included for the analysis, 29 (33%) with RCC and 59 (67%) with UC. Median follow-up was 7.4 months. Median age was 66.5 years (range 29-91 y).Twenty-three pts (26%) were treated with ICI monotherapy and 65 pts (74%) in combination (anti-CTL4, antiangiogenics, PARP inhibitors, FGFR inhibitors). Forty-seven pts (53%) received ICI as second-line therapy or later. By RECIST v1.1, 26 (30%), 19 (21%) and 43(49%) pts had a best response of progressive disease, stable disease or partial+complete response, respectively. We identified 9 pts (10%) who meet the HPD criteria, 2 pts with RCC and 7 with UC. HPD was associated with anemia at baseline (p = 0.058). Pts with HPD had a trend toward lower overall survival (OS) compared with pts with non-HPD (8.87 vs 4.77 months; p = 0.065). Conclusions: These findings demonstrate that HPD is a phenomenon seen in a significant proportion of pts with RCC and UC and should be taken in account. We found that HPD is associated with poor OS and the anemia at baseline was correlated with HPD.

[ECMO support in a child with cardiogenic shock due to Kingella Kingae endocarditis]

INTRODUCTION

Endocarditis is a rare disease in children, especially in those without previous heart disease, and Kingella Kingae (KK) is rarely identified as the cause. Extracorporeal membrane oxyge nation (ECMO) is a support for both heart and respiratory failure.

OBJECTIVE

To report the first case of infectious endocarditis (IE) due to KK which required ECMO support secondary to refractory cardiogenic shock.

CLINICAL CASE

19-months-old previously healthy female patient, with a 2-day his tory of fever, and diagnosed with hand-foot-and-mouth disease. The patient developed refractory cardiogenic shock, multiorgan failure, acute respiratory distress syndrome, and deep hemodynamic compromise that required veno-arterial ECMO support. The echography showed an image compa tible with mitral valve vegetation, confirming IE with transthoracic echocardiography. Blood culture was positive for KK. She had an ischemic stroke and required two heart surgeries, the first one for the mass resection and the second one for mitral valve repair, which had a posterior ring pseudoa neurysm. The patient had a favorable evolution and was discharged 73 days after admission. At one year of follow-up, she had no cardiological symptoms, but a mild right brachial-crural hemiparesis persisted.

CONCLUSION

This is the first reported case of IE due to KK that required extracorporeal life support. KK endocarditis is an uncommon pathology that can cause multiorgan failure, which can be successfully supported with ECMO.

Relevance of Reference Centers in Sarcoma Care and Quality Item Evaluation: Results from the Prospective Registry of the Spanish Group for Research in Sarcoma (GEIS)

BACKGROUND

Reference centers (RCs) are a key point for improving the survival of patients with soft-tissue sarcomas (STS). The aim of this study was to evaluate selected items in the management of patients with STS, comparing results between RC and local hospitals (LHs).

MATERIALS AND METHODS

Diagnostic and therapeutic data from patients diagnosed between January 2004 and December 2011 were collected. Correlation with outcome was performed.

RESULTS

A total of 622 sarcomas were analyzed, with a median follow-up of 40 months. Imaging of primary tumor preoperatively (yes vs. no) correlated with a higher probability of free surgical margins (77.4% versus 53.7%; p = .006). The provenance of the biopsy (RC vs. LH) significantly affected relapse-free survival (RFS; 3-year RFS 66% vs. 46%, respectively; p = .019). Likewise, 3-year RFS was significantly worse in cases with infiltrated (55.6%) or unknown (43.4%) microscopic surgical margins compared with free margins (63.6%; p < .001). Patients managed by RCs had a better 3-year overall survival compared with those managed by LHs (82% vs. 70.4%, respectively; p = .003). Perioperative chemotherapy in high-risk STS, more frequently administered in RCs than in LHs, resulted in significantly better 3-year RFS (66% vs. 44%; p = .011). In addition, patients with stage IV disease treated in RCs survived significantly longer compared with those in LHs (30.4 months vs. 18.5 months; p = .036).

CONCLUSION

Our series indicate that selected quality-of-care items were accomplished better by RCs over LHs, all with significant prognostic value in patients with STS. Early referral to an RC should be mandatory if the aim is to improve the survival of patients with STS.

IMPLICATIONS FOR PRACTICE

This prospective study in patients diagnosed with soft-tissue sarcoma shows the prognostic impact of reference centers in the management of these patients. The magnitude of this impact encompasses all steps of the process, from the initial management (performing diagnostic biopsy) to the advanced disease setting. This is the first prospective evidence showing improvement in outcomes of patients with metastatic disease when they are managed in centers with expertise. This study provides extra data supporting referral of patients with sarcoma to reference centers.

Clinicopathological and Molecular Characterization of Metastatic Gastrointestinal Stromal Tumors with Prolonged Benefit to Frontline Imatinib

BACKGROUND

Oncogenic KIT/PDGFRA signaling inhibition with imatinib achieves disease control in most patients with advanced/metastatic gastrointestinal stromal tumor (GIST), but resistance eventually develops after 20-24 months. Notably, a small subset of these patients obtain durable benefit from imatinib therapy.

METHODS

We analyzed clinical, pathological, and molecular characteristics and long-term outcomes in patients with metastatic GIST treated with continuous daily dosing of frontline imatinib in a cohort of patients benefiting for ≥5 years. A control group was obtained from the national Spanish Group for Sarcoma Research database and used as comparator.

RESULTS

Sixty-four imatinib long-term responders (LTRs) and 70 control cases were identified. Compared with controls, LTRs at baseline had better performance status (PS) 0-1 (100% vs. 81%), lower mitotic count (median, 8 vs. 15), and tumor burden (number of metastases, 3 vs. 7). KIT exon 11 was the only region found mutated in LTRs. LTRs achieved 34% complete responses and a median progression-free survival of 11 years, compared with 4% and 2 years, respectively, in the control cohort. Prognostic factors that independently predicted long-term benefit with imatinib were PS, number of metastases prior to imatinib, and response to imatinib. Fifteen LTR patients developed new side effects attributable to imatinib after ≥5 years of continuous treatment. No resistance mutations were found in metastatic samples from three patients progressing on imatinib.

CONCLUSION

GISTs in LTRs are a distinctive entity with less aggressive behavior and marked sensitivity to KIT inhibition. Patients reaching 5 or more years on imatinib have a higher chance of remaining progression free over time.

IMPLICATIONS FOR PRACTICE

This work demonstrates that clinical and inherent tumor characteristics define a subset of patients with gastrointestinal stromal tumor (GIST) with increased likelihood to achieve durable response to first-line imatinib therapy. Patients reaching ≥5 years on imatinib have a greater chance of remaining progression free over time, although the disease is unlikely to be cured. Imatinib is well tolerated for >5 years, and emergent toxicities are overall manageable. Resistance to imatinib emerging in patients with GISTs after long-term imatinib treatment does not involve polyclonal expansion of KIT secondary mutations.

Nilotinib as Coadjuvant Treatment with Doxorubicin in Patients with Sarcomas: A Phase I Trial of the Spanish Group for Research on Sarcoma

Purpose: Nilotinib plus doxorubicin showed to be synergistic regarding apoptosis in several sarcoma cell lines. A phase I/II trial was thus designed to explore the feasibility of nilotinib as coadjuvant of doxorubicin by inhibiting MRP-1/P-gp efflux activity. The phase I part of the study is presented here.Patients and Methods: Nilotinib 400 mg/12 hours was administered in fixed dose from day 1 to 6, and doxorubicin on day 5 of each cycle. Three dose escalation levels for doxorubicin at 60, 65, and 75 mg/m² were planned. Cycles were repeated every 3 weeks for a total of 4 cycles. Eligible subtypes were retroperitoneal liposarcoma, leiomyosarcoma, and unresectable/metastatic high-grade chondrosarcoma.Results: Thirteen patients were enrolled: 7 chondrosarcoma, 4 liposarcoma, and 2 leiomyosarcoma. In 46 cycles administered, the most relevant grade 3/4 adverse effects per patient were neutropenia 54%, febrile neutropenia 15%, and asthenia 8%. No cardiac toxicity was observed. Only one dose-limiting toxicity (febrile neutropenia) was reported in the third dose level. With regard to efficacy, 1 partial response (1 liposarcoma), 9 stable diseases (5 chondrosarcoma, 2 liposarcoma, 1 leiomyosarcoma), and 3 progressive diseases (2 chondrosarcoma and 1 leiomyosarcoma) were present. ABCB1 and ABCC1 RNA expression levels decreased by 58.47-fold and 1.47-fold, respectively, on day 5 of the cycle.Conclusions: Combination of MRP-1/P-gp inhibitor, nilotinib, as coadjuvant with doxorubicin is feasible; it appears not to add substantial toxicity compared with doxorubicin alone. Pharmacodynamic study supports this concept. The recommended dose for the phase II part for doxorubicin was 75 mg/m² Clin Cancer Res; 24(21); 5239-49. ©2018 AACR.

Malignant bone tumors (other than Ewing's): clinical practice guidelines for diagnosis, treatment and follow-up by Spanish Group for Research on Sarcomas (GEIS)

Primary malignant bone tumors are uncommon and heterogeneous malignancies. This document is a guideline developed by the Spanish Group for Research on Sarcoma with the participation of different specialists involved in the diagnosis and treatment of bone sarcomas. The aim is to provide practical recommendations with the intention of helping in the clinical decision-making process. The diagnosis and treatment of bone tumors requires a multidisciplinary approach, involving as a minimum pathologists, radiologists, surgeons, and radiation and medical oncologists. Early referral to a specialist center could improve patients' survival. The multidisciplinary management of osteosarcoma, chondrosarcoma, chordoma, giant cell tumor of bone and other rare bone tumors is reviewed in this guideline. Ewing's sarcoma will be the focus of a separate guideline because of its specific biological, clinical and therapeutic features. Each statement has been accompanied by the level of evidence and grade of recommendation on the basis of the available data. Surgical excision is the mainstay of treatment of a localized bone tumor, with various techniques available depending on the histologic type, grade and location of the tumor. Chemotherapy plays an important role in some chemosensitive subtypes (such as high-grade osteosarcoma). In other subtypes, historically considered chemoresistant (such as chordoma or giant cell tumor of bone), new targeted therapies have emerged recently, with a very significant efficacy in the case of denosumab. Radiation therapy is usually necessary in the treatment of chordoma and sometimes of other bone tumors.