[Gastrointestinal stromal tumors : Where do we stand?]

For more than 20 years gastrointestinal stromal tumors (GIST) have been a paradigm for a targeted treatment with tyrosine kinase inhibitors. A fundamental prerequisite for a neoadjuvant or adjuvant treatment of localized GIST or an additive treatment of metastatic GIST is the molecular typing of tumors, ideally at the initial diagnosis. In addition, the possibility of a hereditary or syndromic predisposition must be considered because this results in consequences for the treatment and a different follow-up strategy.

KIT ATP-Binding Pocket/Activation Loop Mutations in GI Stromal Tumor: Emerging Mechanisms of Kinase Inhibitor Escape

PURPOSE

Imatinib resistance in GI stromal tumors (GISTs) is primarily caused by secondary KIT mutations, and clonal heterogeneity of these secondary mutations represents a major treatment obstacle. KIT inhibitors used after imatinib have clinical activity, albeit with limited benefit. Ripretinib is a potent inhibitor of secondary KIT mutations in the activation loop (AL). However, clinical benefit in fourth line remains limited and the molecular mechanisms of ripretinib resistance are largely unknown.

PATIENTS AND METHODS

Progressing lesions of 25 patients with GISTs refractory to ripretinib were sequenced for KIT resistance mutations. Resistant genotypes were validated and characterized using novel cell line models and in silico modeling.

RESULTS

GISTs progressing on ripretinib were enriched for secondary mutations in the ATP-binding pocket (AP), which frequently occur in cis with preexisting AL mutations, resulting in highly resistant AP/AL genotypes. AP/AL mutations were rarely observed in a cohort of progressing GIST samples from the preripretinib era but represented 50% of secondary KIT mutations in patients with tumors resistant to ripretinib. In GIST cell lines harboring secondary KIT AL mutations, the sole genomic escape mechanisms during ripretinib drug selection were AP/AL mutations. Ripretinib and sunitinib synergize against mixed clones with secondary AP or AL mutants but do not suppress clones with AP/AL genotypes.

CONCLUSION

Our findings underscore that KIT remains the central oncogenic driver even in late lines of GIST therapy. KIT-inhibitor combinations may suppress resistance because of secondary KIT mutations. However, the emergence of KIT AP/AL mutations after ripretinib treatment calls for new strategies in the development of next-generation KIT inhibitors.

PD-L1 on large extracellular vesicles is a predictive biomarker for therapy response in tissue PD-L1-low and -negative patients with non-small cell lung cancer

Immunotherapy has revolutionized the treatment of patients with non-small cell lung cancer (NSCLC). High expression of tissue PD-L1 (tPD-L1) is currently the only approved biomarker for predicting treatment response. However, even tPD-L1 low (1-49%) and absent (<1%) patients might benefit from immunotherapy but, to date, there is no reliable biomarker, that can predict response in this particular patient subgroup. This study aimed to test whether tumour-associated extracellular vesicles (EVs) could fill this gap. Using NSCLC cell lines, we identified a panel of tumour-related antigens that were enriched on large EVs (lEVs) compared to smaller EVs. The levels of lEVs carrying these antigens were significantly elevated in plasma of NSCLC patients (n = 108) and discriminated them from controls (n = 77). Among the tested antigens, we focused on programmed cell death ligand 1 (PD-L1), which is a well-known direct target for immunotherapy. In plasma lEVs, PD-L1 was mainly found on a population of CD45- /CD62P+ lEVs and thus seemed to be associated with platelet-derived vesicles. Patients with high baseline levels of PD-L1+ lEVs in blood showed a significantly better response to immunotherapy and prolonged survival. This was particularly true in the subgroup of NSCLC patients with low or absent tPD-L1 expression, thus identifying PD-L1-positive lEVs in plasma as a novel predictive and prognostic marker for immunotherapy.

Trauma and sporadic desmoid tumor development: An approach toward real incidence and aspects of causality

OBJECTIVES

The development of desmoid tumors (DT) is associated with trauma, which is an aspect with medicolegal relevance. The objective of this study was to analyze the proportion and type of trauma (surgical, blunt/fracture, implants), its lag time, and mutations of the CTNNB1 gene in patients with sporadic DT.

METHODS

We analyzed a prospectively kept database of 381 females and 171 males, median age at disease onset 37.7 years (females) and 39.3 years (males) with a histologically confirmed DT. Patients with germline mutation of the APC gene were excluded. Details of the history particularly of traumatic injuries to the site of DT were provided by 501 patients.

RESULTS

In 164 patients (32.7%), a trauma anteceding DT could be verified with a median lag time of 22.9 months (SD, 7.7 months; range, 9-44 months). A prior surgical procedure was relevant in 98 patients, a blunt trauma in 35 patients, a punctuated trauma (injections, trocar) in 18 patients, and site of an implant in 10 patients. In 220 patients, no trauma was reported (43.9%), and 58 females (11.6%) had a postpregnancy DT in the rectus abdominis muscle. In 42 patients (8.4%), data were inconclusive. The distribution of mutations in the CTNNB1 gene (codon 41 vs. 45) was similar in patients with and without a history of trauma before DT development.

CONCLUSIONS

A significant subgroup of patients suffers from a trauma-associated DT, predominantly at a prior surgical site including implants to breast or groin, accounting for 77.9% of the cases, whereas blunt trauma was responsible in 22.1%. We found no data to support that trauma-associated DT have different molecular features in the CTNNB1 gene.

Immunohistochemical expression of TROP‑2 (TACSTD2) on the urothelial carcinoma of the urinary bladder and other types of cancer

In metastatic or locally advanced urothelial carcinoma (UC), therapeutic options have been limited to chemotherapy and immune checkpoint inhibitors. Novel targets and drugs such as antibody drug conjugates have been developed, and enfortumab vedotin targeting nectin-4 and sacituzumab govitecan (SG) targeting trophoblast cell surface antigen 2 (TROP-2), the protein product of the TACSTD2 gene, have been approved. The expression of TROP-2 was investigated within UC and other types of carcinomas, and within the tissue of different healthy organs to understand treatment responses and toxicities. The expression of TROP-2 in the tissues of 42 patients with UC, 13 patients with other types of cancer and in the normal tissues of 11 patients was retrospectively analyzed. Immunohistochemical staining of the TROP-2 protein was performed on a BenchMark ULTRA IHC/ISH System (Roche Tissue Diagnostics; Roche Diagnostics, Ltd.) according to accredited staining protocols in a routine immunohistochemistry accredited and certified facility of the laboratory of immunohistochemistry at the Institute of Pathology (Gerhard-Domagk Institute)- University Hospital Muenster (UKM)-Muenster-Germany]. Different expression levels of TROP-2 were observed, and the highest expression rate of TROP-2 was observed in UC, independent of the tumor stage. However, normal urothelial cells had similar expression levels. Except for ductal carcinoma in situ, the expression of TROP-2 was reduced in other types of cancer and in the healthy tissues from other organs, including pancreas, gall bladder, colon and prostate. Given the treatment response based on the expression level of TROP-2, SG would be effective in almost all cases of UC. However, it would also have an effect on the normal urothelium.

A Systematic Review and Illustrative Case Presentation of Low-Grade Myofibroblastic Sarcoma (LGMS) of the Extremities

INTRODUCTION

Low-grade myofibroblastic sarcoma (LGMS) is a rare tumor entity which occurs in the subcutaneous and deep soft tissues; it is less common in the bone with a predilection for the extremities and the head and neck region. As confirming the diagnosis is difficult and treatment strategies are not standardized, we aimed to identify patient and tumor characteristics, and to summarize treatment strategies and their clinical outcomes to guide surgeons.

METHODS

Included were full articles reporting patients with histology of LGMS in the extremities, excluding tumors of the trunk. All patients underwent surgery but with different extend, from marginal to wide resection. Included studies should inform about local recurrence, metastasis, or evidence of disease, depending on the surgical treatment. We conducted a structured search using MEDLINE (via PubMed), Web of Science, EMBASE and Cochrane Central Register of Controlled Trials (CENTRAL) to identify studies on low-grade myofibroblastic sarcoma of the extremities. Study designs like randomized controlled trials, systematic reviews, prospective trials, retrospective studies, and case reports were included. Prospective studies and comparative studies were not available at all. Therefore, meta-analysis was not possible and statistical analysis was purely descriptive.

RESULTS

Of the 789 studies identified from our initial search, 17 studies including 59 cases reported LGMS of the extremities with the surgical treatment and clinical outcome and were therefore analyzed. In addition, we present the rare case and surgical management of a 28-year-old male patient with residual LGMS of the thumb after an initial incomplete resection. The current literature suggests that a wide excision with R0 margins should be considered the standard treatment for LGMS. In cases where surgery leads to significant functional impairment, individual options like free tissue transfer from a donor site have to be considered. Therefore, we also present an illustrative case. For all selected case series and case reports, a high risk of confounding, selection bias, information bias, and reporting bias must be anticipated. Nevertheless, this systematic review provides a comprehensive overview on surgical treatment and clinical outcomes in LGMS surgery of the extremities.

Acid-base homeostasis orchestrated by NHE1 defines the pancreatic stellate cell phenotype in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) progresses in an organ with a unique pH landscape, where the stroma acidifies after each meal. We hypothesized that disrupting this pH landscape during PDAC progression triggers pancreatic stellate cells (PSCs) and cancer-associated fibroblasts (CAFs) to induce PDAC fibrosis. We revealed that alkaline environmental pH was sufficient to induce PSC differentiation to a myofibroblastic phenotype. We then mechanistically dissected this finding, focusing on the involvement of the Na+/H+ exchanger NHE1. Perturbing cellular pH homeostasis by inhibiting NHE1 with cariporide partially altered the myofibroblastic PSC phenotype. To show the relevance of this finding in vivo, we targeted NHE1 in murine PDAC (KPfC). Indeed, tumor fibrosis decreased when mice received the NHE1-inhibitor cariporide in addition to gemcitabine treatment. Moreover, the tumor immune infiltrate shifted from granulocyte rich to more lymphocytic. Taken together, our study provides mechanistic evidence on how the pancreatic pH landscape shapes pancreatic cancer through tuning PSC differentiation.

KIT and PDGFRA Mutations and Survival of Gastrointestinal Stromal Tumor Patients Treated with Adjuvant Imatinib in a Randomized Trial

PURPOSE

Limited data are available about the influence of KIT and PDGFRA mutations on overall survival (OS) of patients with gastrointestinal stromal tumor (GIST) treated with adjuvant imatinib.

PATIENTS AND METHODS

The Scandinavian Sarcoma Group XVIII/AIO multicenter trial accrued 400 patients with a high risk for GIST recurrence after macroscopically complete surgery between February 4, 2004, and September 29, 2008. The patients received adjuvant imatinib 400 mg/day for either 1 year or 3 years based on random allocation. We analyzed using conventional sequencing KIT and PDGFRA mutations centrally from 341 (85%) patients who had localized, centrally confirmed GIST, and correlated the results with recurrence-free survival (RFS) and OS in exploratory analyses.

RESULTS

During a median follow-up time of 10 years, 164 RFS events and 76 deaths occurred. Most patients were re-treated with imatinib when GIST recurred. Patients with KIT exon 11 deletion or indel mutation treated with 3 years of adjuvant imatinib survived longer than patients treated for 1 year [10-year OS 86% versus 64%, respectively; HR, 0.34; 95% confidence interval (CI), 0.15-0.72; P = 0.007], and also had longer RFS (10-year RFS 47% versus 29%; HR, 0.48; 95% CI, 0.31-0.74; P < 0.001). Patients with KIT exon 9 mutation had unfavorable OS regardless of the duration of adjuvant imatinib.

CONCLUSIONS

Compared with 1 year of imatinib, 3 years of adjuvant imatinib led to 66% reduction in the estimated risk of death and a high 10-year OS rate in the subset of patients with a KIT exon 11 deletion/indel mutation.

Health related Quality of Life over time in German sarcoma patients. An analysis of associated factors - results of the PROSa study

Introduction

Sarcomas are rare cancers and very heterogeneous in their location, histological subtype, and treatment. Health-Related Quality of Life (HRQoL) of sarcoma patients has rarely been investigated in longitudinal studies.

Methods

Here, we assessed adult sarcoma patients and survivors between September 2017 and February 2020, and followed-up for one year in 39 study centers in Germany. Follow-up time points were 6 (t1) and 12 months (t2) after inclusion. We used a standardized, validated questionnaire (the European Organisation for Research and Treatment of Cancer Quality of Life Core Instrument (EORTC QLQ-C30) and explored predictors of HRQoL in two populations (all patients (Analysis 1), patients in ongoing complete remission (Analysis 2)) using generalized linear mixed models.

Results

In total we included up to 1111 patients at baseline (915 at t1, and 847 at t2), thereof 387 participants were in complete remission at baseline (334 at t1, and 200 at t2). When analyzing all patients, HRQoL differed with regard to tumor locations: patients with sarcoma in lower extremities reported lower HRQoL values than patients with sarcomas in the upper extremities. Treatment which included radiotherapy and/or systemic therapy was associated with lower HRQoL. For patients in complete remission, smoking was associated with worse HRQoL-outcomes. In both analyses, bone sarcomas were associated with the worst HRQoL values. Being female, in the age group 55-<65 years, having lower socioeconomic status, and comorbidities were all associated with a lower HRQoL, in both analyses.

Discussion

HRQoL increased partially over time since treatment and with sporting activities. HRQoL improved with time since treatment, although not in all domains, and was associated with lifestyle and socioeconomic factors. Bone sarcomas were the most affected subgroup. Methods to preserve and improve HRQoL should be developed for sarcoma patients.

Complete Metabolic Response to Combined Immune Checkpoint Inhibition after Progression of Metastatic Colorectal Cancer on Pembrolizumab: A Case Report

DNA mismatch repair deficient (dMMR) and microsatellite instable (MSI) metastatic colorectal cancer (mCRC) can be successfully treated with FDA- and EMA-approved immune checkpoint inhibitors (ICI) pembrolizumab and nivolumab (as single agents targeting the anti-programmed cell death protein-1 (PD-1)) or combinations of a PD-1 inhibitor with ipilimumab, a cytotoxic T-lymphocyte-associated protein 4 (CTLA-4)-targeting antibody. The best treatment strategy beyond progression on single-agent ICI therapy remains unclear. Here, we present the case of a 63-year-old male with Lynch-syndrome-associated, microsatellite instability-high (MSI-H) mCRC who achieved a rapid normalization of his tumor markers and a complete metabolic remission (CMR), currently lasting for ten months, on sequential ICI treatment with the combination of nivolumab and ipilimumab followed by nivolumab maintenance therapy after progression on single-agent anti-PD-1 ICI therapy. The therapy was well-tolerated, and no immune-related adverse events occurred. To the best of our knowledge, this is the first case of a sustained metabolic complete remission in an MSI-H mCRC patient initially progressing on single-agent anti-PD-1 therapy. Thus, dMMR mCRC patients might benefit from sequential immune checkpoint regimens even with long-term responses. However, further sophistication of clinical algorithms for treatment beyond progression on single-agent ICI therapy in MSI-mCRC is urgently needed.

Sarcoma Research with Cancer Registry Data: Data and Peculiarities of Germany in the Light of Other Countries

INTRODUCTION

Sarcomas are documented in population-based and in clinic-associated databases. This study evaluated the status quo regarding the potential and obstacles of cancer registry-based research on sarcomas exemplified by Germany in comparison to similar databases in the US and Europe. Completeness and quality of data are discussed based on statistical analyses of a pooled data set established for the German Cancer Congress 2020.

METHODS

We analyzed data derived from 16 German institutions (federal state cancer registries and some facility-based registries). Malignant sarcomas in adults diagnosed between 2000 and 2018 with information on histology were grouped according to the WHO classification of soft tissue and bone tumors. Descriptive analyses of the study population regarding the distribution of age, sex, histology, localization of primary tumors, and metastases were performed. Survival for the ten most frequent histological groups and UICC stages was evaluated according to Kaplan-Meier and Cox regression. Time interval between surgery and subsequent radiation was calculated.

RESULTS

The initial data set contained 35,091 sarcomas. After several steps of data cleaning, 28,311 patients with known sex and unambiguous assignment to a histological subgroup remained (13,682 women and 14,629 men). Between 40 and 54 years, women were more likely to develop sarcomas, whereas in the older age groups more men were affected. Gastrointestinal stromal tumors, fibroblastic, and myofibroblastic tumors, smooth muscle tumors (mostly non-uterine leiomyosarcomas), and adipocytic tumors represented 48% of all sarcomas. Preferential sites for fibrosarcomas were the limbs, the trunk, and the head and neck region. The liposarcoma occurred most frequently on the trunk and limbs. Distant primary metastases were mostly located in the lung (43%), followed by the liver (14%), and bones (13%). Vascular and smooth muscle tumors showed the worst survival prognosis (5-year survival: approx. 15%, median survival approx. 8-16 months), whereas in low stages, the probability of survival of many sarcoma patients was beyond 5 years. Adjuvant radiotherapy was applied within 90 days in 71% of patients (n = 2,534).

CONCLUSION

Our results correspond to the data from the literature. However, a lack of data quality and completeness hampers further meaningful analyses, especially nonspecific or missing information about morphology and stage. Compared to some other countries, a comprehensive database is presently missing in Germany. However, currently, there are important efforts and legislative initiatives to create a comprehensive database on a national level within the near future.

Radiomics of Tumor Heterogeneity in 18F-FDG-PET-CT for Predicting Response to Immune Checkpoint Inhibition in Therapy-Naïve Patients with Advanced Non-Small-Cell Lung Cancer

We aimed to evaluate the predictive and prognostic value of baseline ¹⁸F-FDG-PET-CT (PET-CT) radiomic features (RFs) for immune checkpoint-inhibitor (CKI)-based first-line therapy in advanced non-small-cell lung cancer (NSCLC) patients. In this retrospective study 44 patients were included. Patients were treated with either CKI-monotherapy or combined CKI-based immunotherapy-chemotherapy as first-line treatment. Treatment response was assessed by the Response Evaluation Criteria in Solid Tumors (RECIST). After a median follow-up of 6.4 months patients were stratified into "responder" (n = 33) and "non-responder" (n = 11). RFs were extracted from baseline PET and CT data after segmenting PET-positive tumor volume of all lesions. A Radiomics-based model was developed based on a Radiomics signature consisting of reliable RFs that allow classification of response and overall progression using multivariate logistic regression. These RF were additionally tested for their prognostic value in all patients by applying a model-derived threshold. Two independent PET-based RFs differentiated well between responders and non-responders. For predicting response, the area under the curve (AUC) was 0.69 for "PET-Skewness" and 0.75 predicting overall progression for "PET-Median". In terms of progression-free survival analysis, patients with a lower value of PET-Skewness (threshold < 0.2014; hazard ratio (HR) 0.17, 95% CI 0.06-0.46; p < 0.001) and higher value of PET-Median (threshold > 0.5233; HR 0.23, 95% CI 0.11-0.49; p < 0.001) had a significantly lower probability of disease progression or death. Our Radiomics-based model might be able to predict response in advanced NSCLC patients treated with CKI-based first-line therapy.

Interdependence of SS18-SSX-driven YAP1 and β-catenin activation in synovial sarcoma

Synovial sarcoma (SySa), a rare malignant soft tissue tumor, is characterized by a specific chromosomal translocation t(X;18). The resulting chimeric SS18-SSX fusion protein drives SySa pathogenesis by integrating into the BAF complex and dysregulating gene transcription. Since previous functional analyses revealed a connection between SS18-SSX and the activity of the transcriptional co-regulators YAP1/TAZ and β-catenin, respectively, this study examined a potential interdependence between these essential effector proteins in SySa. In a large cohort of SySa tissue specimens, immunohistochemical analyses revealed a substantial subset of SySa with concurrent nuclear accumulation of YAP1/TAZ and β‑catenin. In vitro, small molecule inhibitor treatment, RNAi-mediated knockdown and vector-based overexpression assays demonstrated that YAP1, TAZ and β-catenin transcriptional activity is not only stimulated by the SS18-SSX fusion protein, but that they also mutually enhance each other's activation. These analyses showed the highest cooperative effect with overexpression of YAP1 in combination with β-catenin. Co-immunoprecipitation experiments detected nuclear interactions between YAP1, β-catenin and the SS18-SSX fusion protein, the latter being an integral part of the BAF complex. Disruption of BAF complex assembly affected the coregulation of YAP1 and β-catenin, indicating that this chromatin remodeling complex plays a crucial role for interdependent YAP1 and β-catenin activation in SySa cells. Implications: This study provides deeper insights into SySa tumor biology demonstrating a mutual dependence between YAP1/TAZ and β-catenin transcriptional activity and a complex interplay with the SS18-SSX fusion protein within the BAF complex.

Recurrent EWSR1::COLCA2 Fusions Define a Novel Sarcoma With Spindle/Round Cell Morphology and Strong Predilection for the Sinonasal Tract

The last 2 decades have attended a dynamic evolution in the nosology of poorly differentiated sinonasal tract malignancies, with several new molecularly defined entities having been described in addition to delineation of the genetic driver/s of some established older entities. These discoveries, however, mostly concerned epithelial-derived neoplasms (carcinomas). Adamantinoma-like Ewing sarcoma and biphenotypic sinonasal sarcoma are the major representatives of the newly defined mesenchymal categories. The colorectal cancer associated 2 (COLCA2) has been discovered recently as a colorectal cancer risk gene locus, but fusions involving this gene have not been well characterized. We, herein, describe clinicopathologic and molecular features of a novel sinonasal sarcoma characterized by undifferentiated spindle/round cell morphology and defined by recurrent EWSR1::COLCA2 fusions. All patients (n=5) were adults (3 female and 2 male) with a median age of 46 years (range, 23 to 60 y). The tumors originated in different subsites of the sinonasal tract with frequent multisite involvement. Original diagnoses were undifferentiated or unclassified round cell/spindle cell neoplasm/sarcoma (n=4) and neuroendocrine carcinoma (n=1). Surgery with or without adjuvant chemoradiation was the treatment in all cases. At the last follow-up, 1 patient developed multiple local recurrences over 21 years and another developed local recurrence and distant metastasis to bone 27 months after diagnosis. A third patient developed local recurrence 11 months later. Two patients were disease-free at 23, and 24 months. Histology showed nondescript highly cellular neoplasms with an admixture of spindled and round cells disposed into solid sheets and fascicles with brisk mitotic activity. Immunohistochemistry was negative for all lineage-specific markers with only limited focal membranous CD99 (4 of 5 cases) and weak pankeratin (1 of 5 cases) expression. Targeted RNA sequencing revealed an EWSR1::COLCA2 fusion, verified by EWSR1 fluorescence in situ hybridization, in all cases. This series identifies a novel member in the undifferentiated spindle/round cell sarcoma category with strong predilection for the sinonasal tract. None of >10,000 epithelial and mesenchymal neoplasms tested at the authors' centers during the same period showed this fusion, highlighting rarity of tumors carrying this gene fusion. Accordingly, molecular testing of unclassified sinonasal malignancies/sarcomas showing round and spindle cell morphology is recommended to enhance the identification and further characterization of this entity.

Efficacy of Multimodality Approach in Patients With Recurrent Head and Neck Squamous Cell Carcinoma

BACKGROUND/AIM

Head and neck squamous cell carcinoma (HNSCC) is characterized by high relapse rates and low survival in comparison to other malignancies.

PATIENTS AND METHODS

Fifty-two patients suffering from recurrent HNSCC were compared, analyzing the impact of different regimes, including surgery, radiotherapy (RT), chemotherapy and immunotherapy on progression-free survival (PFS), overall survival (OS), locoregional control (LRC), and adverse events.

RESULTS

The standard RT technique was intensity-modulated radiotherapy (IMRT) in all patients. In the multivariate analysis, higher cumulative RT dose significantly influenced LRC whereas surgery and age significantly impacted PFS and OS.

CONCLUSION

IMRT dose-escalation, as well as surgery, appear beneficial in the treatment of recurrent HNSCC. Moreover, nivolumab and platin-based therapy might be superior agents for systemic therapy in comparison to cetuximab.

Genetic susceptibility in children, adolescents, and young adults diagnosed with soft-tissue sarcomas

Soft tissue sarcomas (STS) may arise as a consequence of germline variants in cancer predisposition genes (CPGs). We believe that elucidating germline sarcoma predisposition is critical for understanding disease biology and therapeutic requirements. Participation in surveillance programs may allow for early tumor detection, early initiation of therapy and, ultimately, better outcomes. Among children, adolescents, and adults diagnosed with soft-tissue sarcomas and examined as part of published germline sequencing studies, pathogenic/likely pathogenic (P/LP) variants in CPGs were reported in 7-33% of patients. P/LP germline variants were detected most frequently in TP53, NF1 and BRCA1/2. In this review, we describe reported associations between soft tissue sarcomas and germline variants in CPGs, with mentioning of locally aggressive and benign soft tissue tumors that have important associations with cancer predisposition syndromes. We also discuss recommendations for diagnostic germline genetic testing. Testing for sarcoma-predisposing germline variants should be considered as part of the routine clinical workup and care of any child, adolescent, or adult diagnosed with STS and take into account consequences for the whole family.

Dataset for reporting of gastrointestinal stromal tumours: recommendations from the International Collaboration on Cancer Reporting (ICCR)

Gastrointestinal stromal tumours (GISTs) are the most common mesenchymal tumours of the gastrointestinal tract and are among the most frequent sarcomas. Accurate diagnosis, classification, and reporting are critical for prognostication and patient management, including selection of appropriate targeted therapy. Here we report on international consensus-based datasets for the pathology reporting of biopsy and resection specimens of GIST. The datasets were produced under the auspices of the International Collaboration on Cancer Reporting (ICCR), a global alliance of major international pathology and cancer organizations. An international expert panel consisting of pathologists, a surgical oncologist, and a medical oncologist produced a set of core and noncore data items for biopsy and resection specimens based on a critical review and discussion of current evidence. All professionals involved were subspecialized soft tissue tumour experts and affiliated with tertiary referral centres. Commentary was provided for each data item to explain its clinical relevance and the rationale for selection as a core or noncore element. Following international public consultation, the datasets, which include synoptic reporting guides, were finalized and ratified, and published on the ICCR website. These first international datasets for GIST are intended to promote high-quality, standardised pathology reporting. Their widespread adoption will improve consistency of reporting, facilitate multidisciplinary communication, and enhance comparability of data, all of which will ultimately help to improve the management of patients with GIST. All the ICCR datasets, including these on GIST, are freely available worldwide on the ICCR website (www.iccr-cancer.org/datasets).

Controversies in the management of patients with soft tissue sarcoma: Recommendations of the Conference on State of Science in Sarcoma 2022

BACKGROUND

Owing to the rarity and heterogeneity in biology and presentation, there are multiple areas in the diagnosis, treatment and follow-up of soft tissue sarcoma (STS), with no, low-level or conflicting evidence.

METHODS

During the first Consensus Conference on the State of Science in Sarcoma (CSSS), we used a modified Delphi process to identify areas of controversy in the field of sarcoma, to name topics with limited evidence-based data in which a scientific and knowledge gap may remain and a consensus statement will help to guide patient management. We determined scientific questions which need to be addressed in the future in order to generate evidence and to inform physicians and caregivers in daily clinical practice in order to improve the outcomes of patients with sarcoma. We conducted a vote on STS key questions and controversies prior to the CSSS meeting, which took place in May 2022.

RESULTS

Sixty-two European sarcoma experts participated in the survey. Sixteen strong consensus (≥95%) items were identified by the experts, as well as 30 items with a ≥75% consensus on diagnostic and therapeutic questions. Ultimately, many controversy topics remained without consensus.

CONCLUSIONS

In this manuscript, we summarise the voting results and the discussion during the CSSS meeting. Future scientific questions, priorities for clinical trials, registries, quality assurance, and action by stakeholders are proposed. Platforms and partnerships can support innovative approaches to improve management and clinical research in STS.

Comprehensive molecular profiling of sarcomas in adolescent and young adult patients: Results of the EORTC SPECTA-AYA international proof-of-concept study

BACKGROUND

Adolescent and young adult (AYA) patients with cancer are poorly recruited to molecularly targeted trials and have not witnessed the advances in cancer treatment and survival seen in other age groups. We report here a pan-European proof-of-concept study to identify actionable alterations in some of the worst prognosis AYA cancers: bone and soft tissue sarcomas.

DESIGN

Patients aged 12-29 years with newly diagnosed or recurrent, intermediate or high-grade bone and soft tissue sarcomas were recruited from six European countries. Pathological diagnoses were centrally reviewed. Formalin-fixed tissues were analysed by whole exome sequencing, methylation profiling and RNA sequencing and were discussed in a multidisciplinary, international molecular tumour board.

RESULTS

Of 71 patients recruited, 48 (median 20 years, range 12-28) met eligibility criteria. Central pathological review confirmed, modified and re-classified the diagnosis in 41, 3, and 4 cases, respectively. Median turnaround time to discussion at molecular tumour board was 8.4 weeks. whole exome sequencing (n = 48), methylation profiling (n = 44, 85%) and RNA sequencing (n = 24, 50%) led to therapeutic recommendations for 81% patients, including 4 with germ line alterations. The most common were for agents targeted towards tyrosine kinases (n = 20 recommendations), DNA repair (n = 18) and the PI3K/mTOR/AKT pathway (n = 15). Recommendations were generally based on weak evidence such as activity in a different tumour type (n = 68, 61%), reflecting the dearth of relevant molecular clinical trial data in the same tumour type.

CONCLUSIONS

We demonstrate here that comprehensive molecular profiling of AYA patients' samples is feasible and deliverable in a European programme.

New benchmarks to design clinical trials with advanced or metastatic liposarcoma or synovial sarcoma patients: An EORTC - Soft Tissue and Bone Sarcoma Group (STBSG) meta-analysis based on a literature review for soft-tissue sarcomas

BACKGROUND

Recently, we performed a meta-analysis based on a literature review for STS trials (published 2003-2018, ≥10 adult patients) to update long-standing reference values for leiomyosarcomas. This work is extended for liposarcomas (LPS) and synovial sarcomas (SS).

MATERIALS AND METHODS

Study endpoints were progression-free survival rates (PFSRs) at 3 and 6 months. Trial-specific estimates were pooled per treatment line (first-line or pre-treated) with random effects meta-analyses. The choice of the therapeutic benefit to target in future trials was guided by the European Society for Medical Oncology Magnitude of Clinical Benefit Scale (ESMO-MCBS).

RESULTS

Information was acquired for 1030 LPS patients (25 trials; 7 first-line, 17 pre-treated, 1 both) and 348 SS patients (13 trials; 3 first-line, 10 pre-treated). For LPS, the overall pooled first-line PFSRs were 69% (95%-CI 60-77%) and 56% (95%-CI 45-67%) at 3 and 6 months, respectively. These rates were 49% (95%-CI 40-57%)/28% (95%-CI 22-34%) for >1 lines. For SS, first-line PFSRs were 74% (95%-CI 58-86%)/56% (95%-CI 31-78%) at 3 and 6 months, and pre-treated rates were 45% (95%-CI 34-57%)/25% (95%-CI 16-36%). Following ESMO-MCBS guidelines, the minimum values to target are 79% and 69% for first-line LPS (82% and 69% for SS) at 3 and 6 months. For pre-treated LPS, recommended PFSRs at 3 and 6 months suggesting drug activity are 63% and 44% (60% and 41% for SS).

CONCLUSIONS

New benchmarks are proposed for advanced/metastatic LPS or SS to design future histology-specific phase II trials. More data are needed to provide definitive thresholds for the different LPS subtypes.

Abstract A027: Characterization of WEE1 kinase activity in myxoid liposarcoma

Introduction: Myxoid liposarcomas (MLS), malignant soft tissue tumors of adipocyte origin, are genetically characterized by a chromosomal t(12;16)(q13;p11) translocation encoding the chimeric FUS-DDIT3 fusion gene. The resulting fusion protein drives MLS pathogenesis via (dys-)regulation of oncogenic signaling pathways. Since FUS-DDIT3 is not selectively antagonizable, counteracting the oncogenic effects of FUS-DDIT3 fusion protein represents the most promising strategy to target MLS cells. In this study, we identified cell cycle checkpoint kinase WEE1 as FUS-DDIT3 depending effector and investigated the functional requirement for WEE1 kinase activity in MLS pathogenesis. Experimental Procedures: Characterization of WEE1 expression and kinase activity was performed in multiple MLS cell lines, cell lines derived from other liposarcoma subtypes and a mesenchymal stem cell system. Modulation of WEE1 signaling was carried out by means of small-molecule inhibitor Adavosertib (MK-1775) and RNA interference (RNAi)-mediated depletion, and effects were analyzed in immunoblots, cell proliferation assays and caspase 3/7 activity-based apoptosis assays in vitro. Results: Functional genomic RNAi screening uncovered dependence of FUS-DDIT3-expressing mesenchymal stem cells and MLS cell lines on WEE1 kinase activity. Additional expression analysis revealed increased WEE1 protein levels in MLS cell lines. Moreover, pharmacologic inhibition of WEE1 demonstrated significant reduction of MLS cell viability. Accordingly, functional loss of WEE1 by inhibition or RNAi-mediated depletion was found to induce DNA damage accompanied by unscheduled mitotic entry and cell death via activation of the apoptotic program in MLS cells. Conclusions: Our results identify WEE1 kinase activity as functional liability of FUS-DDIT3 expressing MLS cells and provide first evidence that overactive WEE1 signaling represents a promising target for therapeutic intervention in MLS.

Citation Format: Lorena Heinst, Ruth Berthold, Ilka Isfort, Svenja Wosnig, Thomas Kindler, Pierre Åman, Eva Wardelmann, Claudia Scholl, Stefan Fröhling, Wolfgang Hartmann, Marcel Trautmann. Characterization of WEE1 kinase activity in myxoid liposarcoma [abstract]. In: Proceedings of the AACR Special Conference: Sarcomas; 2022 May 9-12; Montreal, QC, Canada. Philadelphia (PA): AACR; Clin Cancer Res 2022;28(18_Suppl):Abstract nr A027.

Abstract A031: Interplay of YAP1, β-catenin and the SS18-SSX fusion protein in synovial sarcoma

Introduction: Synovial sarcoma (SySa) is a rare soft-tissue malignancy characterized by a specific chromosomal translocation t(X;18). The resulting chimeric SS18-SSX fusion protein drives SySa pathogenesis by dysregulating gene transcription. As therapeutic targeting of SS18-SSX is notoriously difficult, the identification of SS18-SSX-dependent pathomechanisms may uncover novel molecular vulnerabilities. Since previous functional analyses revealed a connection between SS18-SSX and the activity of the transcriptional co-regulators YAP1/TAZ and β-catenin, this study examined a potential crosstalk between these effectors in SySa. Experimental Procedures: Nuclear abundance of YAP1/TAZ and β-catenin was analyzed by immunohistochemistry in a large cohort of SySa tissue specimens. Two SySa cell lines were employed to modulate YAP1/TAZ/β-catenin transcriptional activity by RNAi-mediated knockdown, small molecule inhibitors, and overexpression vectors in vitro. Changes in transcriptional activity were determined via luciferase reporter assays. As YAP1 and β-catenin showed highest interdependence, co-immunoprecipitation experiments were performed to investigate their interplay with the SS18-SSX fusion protein in SySa cells. Results: Immunohistochemically, a substantial subset of SySa tissue specimens showed concurrent nuclear accumulation of YAP1/TAZ and β-catenin. In vitro, SS18-SSX was found to promote YAP1/TAZ and β-catenin transcriptional activity. RNAi-mediated knockdown of YAP1, TAZ or β-catenin and small molecule inhibitor treatment mutually downregulated TEAD and TCF luciferase reporter activity, while expression of hyperactive variants led to a reciprocal luciferase reporter induction. Finally, co-immunoprecipitation assays demonstrated nuclear co-localization of SS18-SSX with YAP1 and β-catenin in SySa cell lines. Conclusions: This study reveals an interdependency between YAP1 and β-catenin activation and a complex interplay with the SySa-specific SS18-SSX fusion protein.

Citation Format: Ilka Isfort, Ruth Berthold, Lorena Heinst, Eva Wardelmann, Marcel Trautmann, Wolfgang Hartmann. Interplay of YAP1, β-catenin and the SS18-SSX fusion protein in synovial sarcoma [abstract]. In: Proceedings of the AACR Special Conference: Sarcomas; 2022 May 9-12; Montreal, QC, Canada. Philadelphia (PA): AACR; Clin Cancer Res 2022;28(18_Suppl):Abstract nr A031.

Abstract PR004: Fusion protein-driven IGF-IR signals deregulate hippo pathway promoting oncogenic cooperation of YAP1 and FUS-DDIT3

Introduction: Myxoid liposarcoma (MLS) is molecularly characterized by a recurrent chromosomal translocation which generates a chimeric FUS-DDIT3 fusion gene. The FUS-DDIT3 oncoprotein, acting as a transcriptional dysregulator, has been shown to be essential in MLS pathogenesis, among others through deregulation of IGF-IR/PI3K/AKT signaling, but its exact mode of function remains incompletely understood. Recently, a particular reliance on the Hippo pathway effector and transcriptional co-regulator YAP1 was found in MLS; however, the molecular mechanism of FUS-DDIT3-dependent YAP1 activation and its contribution to MLS pathogenesis remain unclear. Experimental Procedures: The expression of IGF-IR and YAP1 was analyzed in a large cohort of MLS specimens by immunohistochemistry. In vitro analyses were performed employing a human mesenchymal stem cell system stably expressing FUS-DDIT3 and human MLS cell lines. RNA interference-based approaches, experiments with small-molecule kinase inhibitors, co-immunoprecipitation, proximity ligation assays, transcriptome sequencing and adipogenic differentiation assays were performed to determine the interplay of FUS-DDIT3, IGF-IR-dependent signals, and YAP1 in MLS cells. Results: Immunohistochemically, a significant subset of MLS samples showed concurrent expression of IGF-IR and nuclear YAP1. In vitro, FUS-DDIT3-driven IGF-IR signaling was found to promote stability and nuclear accumulation of YAP1 via deregulation of the Hippo pathway. Co-immunoprecipitation and proximity ligation assays revealed nuclear co-localization of FUS-DDIT3 and YAP1 in FUS-DDIT3-expressing mesenchymal stem cells and MLS cell lines. Transcriptome sequencing of MLS cells demonstrated that FUS-DDIT3 and YAP1 co-regulate specific oncogenic gene signatures related to proliferation, cell cycle progression, apoptosis, and adipogenesis. In differentiation assays, FUS-DDIT3 and YAP1 were found to cooperate in adipogenic differentiation arrest. Conclusions: Our study provides molecular insights into a complex FUS-DDIT3-driven network involving IGF-IR signals acting on Hippo/YAP1, and uncovers cooperative effects of YAP1 and FUS-DDIT3 in the pathogenesis of MLS.

Citation Format: Ruth Berthold, Ilka Isfort, Cihan Erkut, Lorena Heinst, Inga Grünewald, Eva Wardelmann, Thomas Kindler, Pierre Åman, Thomas G.P. Grünewald, Florencia Cidre-Aranaz, Marcel Trautmann, Stefan Fröhling, Claudia Scholl, Wolfgang Hartmann. Fusion protein-driven IGF-IR signals deregulate hippo pathway promoting oncogenic cooperation of YAP1 and FUS-DDIT3 [abstract]. In: Proceedings of the AACR Special Conference: Sarcomas; 2022 May 9-12; Montreal, QC, Canada. Philadelphia (PA): AACR; Clin Cancer Res 2022;28(18_Suppl):Abstract nr PR004.

Intestinal brush border formation requires a TMIGD1-based intermicrovillar adhesion complex

Intestinal epithelial cells absorb nutrients through the brush border, composed of dense arrays of highly ordered microvilli at their apical membranes. A protocadherin-based intermicrovillar adhesion complex localized at microvilli tips mediates microvilli packing and organization. Here, we identified a second adhesion complex localized at the proximal base region of microvilli. This complex contained the immunoglobulin superfamily member TMIGD1, which directly interacted with the microvillar scaffolding proteins EBP50 and E3KARP. Complex formation with EBP50 required the activation of EBP50 by the actin-binding protein ezrin and was enhanced by the dephosphorylation of Ser¹⁶² in the PDZ2 domain of EBP50 by the phosphatase PP1α. Binding of the EBP50-ezrin complex to TMIGD1 enhanced the dynamic turnover of EBP50 at microvilli. Enterocyte-specific inactivation of Tmigd1 in mice resulted in microvillar blebbing, loss of intermicrovillar adhesion, and perturbed brush border formation. Thus, we identified a second adhesion complex in microvilli and propose a mechanism that promotes microvillar formation and dynamics.

Abstract 2005: First results of the EORTC-SPECTA project on comprehensive molecular profiling of adolescent and young adult sarcoma patients

Introduction: Yearly, around 45,000 new diagnoses of cancer in the adolescent and young adult (AYA) population are made in Europe, with sarcoma and brain tumors being some of the most prevalent tumor types.Despite great progress being made in understanding the molecular landscape of cancer in children and adults, AYA cancer biology is still poorly understood.

Material and Methods: To identify clinically relevant molecular alterations in this patient population, we aimed to recruit 50 evaluable patients aged between 12 and 29 with high-risk, sarcoma at initial diagnosis or relapse, using the EORTC-SPECTA platform (deRojas et al. IJC, 2020) and perform in depth molecular analysis (WES, RNAseq, array-based DNA methylation profiling) and central pathology review. Between April 2019 and July 2020, 71 patients were recruited from nine sites within six European countries. In total, 48 patients were evaluable. The remainder (32%) failed quality control, mainly due to poor quality of the formalin-fixed and paraffin-embedded tumor tissue. Median age at diagnosis was 19 years (range 6 to 28 years), including 25 cases of newly diagnosed sarcoma and 23 cases of recurrent sarcoma.

Results: Central pathology review was performed for all evaluable patients. The local diagnosis was confirmed in 41 cases (85.4%) and changed in 7 cases (14.6%), including new diagnoses of BCOR sarcomas (n=3) and teratoma (n=1). DNA methylation analysis was performed for all cases with adequate DNA (n=46), and profiles were categorized according to the Heidelberg classifier (Koelsche et al., Nature Communication, 2021). The classifier confirmed the diagnosis of central pathology in 32 cases (69.6%). The remaining cases showed discrepancies mainly due to poor DNA quality. Whole-exome and RNA sequencing were performed on all samples where DNA and/or RNA quality permitted (98% and 48% respectively).Pathology and molecular profiling results were discussed at a monthly combined clinico-pathological tumor board, with the goal of adapting treatment strategies based on molecular profile either for this treatment episode or for future progression. Actionable molecular alterations were identified in 39 cases. Treatment was adapted in 3 cases and confirmed in 1. Treatment was not adapted in the remainder because they were undergoing primary treatment (n=14), undergoing an alternative treatment for progression (n=10), due to death prior to molecular tumor board (n=10) or loss to follow-up (n=1).

Conclusion: Despite expected logistic challenges associated with sample quality and analysis, actionable alterations were identified in 81.2% of evaluable patients, confirming that there is an unmet clinical need in this population. Moreover, we have identified remediable organizational factors to reduce sample failures and increase the turnaround speed of recommendations in this overlooked AYA cancer population.

Citation Format: Marie Morfouace, Peter Horak, Simon Kreutzfeldt, Patrick Shenjere, Eva Wardelmann, Evgeniya Denisova, Aleksandra Stevovic, Francisco J. Bautista, Julio Oliveira, Winette van der Graaf, Stefan Fröhling, Martin G. McCabe. First results of the EORTC-SPECTA project on comprehensive molecular profiling of adolescent and young adult sarcoma patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2005.

SS18-SSX drives CREB activation in synovial sarcoma

Purpose

Synovial sarcoma (SySa) is a rare soft tissue tumor characterized by a reciprocal t(X;18) translocation. The chimeric SS18-SSX fusion protein represents the major driver of the disease, acting as aberrant transcriptional dysregulator. Oncogenic mechanisms whereby SS18-SSX mediates sarcomagenesis are incompletely understood, and strategies to selectively target SySa cells remain elusive. Based on results of Phospho-Kinase screening arrays, we here investigate the functional and therapeutic relevance of the transcription factor CREB in SySa tumorigenesis.

Methods

Immunohistochemistry of phosphorylated CREB and its downstream targets (Rb, Cyclin D1, PCNA, Bcl-xL and Bcl-2) was performed in a large cohort of SySa. Functional aspects of CREB activity, including SS18-SSX driven circuits involved in CREB activation, were analyzed in vitro employing five SySa cell lines and a mesenchymal stem cell model. CREB mediated transcriptional activity was modulated by RNAi-mediated knockdown and small molecule inhibitors (666-15, KG-501, NASTRp and Ro 31-8220). Anti-proliferative effects of the CREB inhibitor 666-15 were tested in SySa avian chorioallantoic membrane and murine xenograft models in vivo.

Results

We show that CREB is phosphorylated and activated in SySa, accompanied by downstream target expression. Human mesenchymal stem cells engineered to express SS18-SSX promote CREB expression and phosphorylation. Conversely, RNAi-mediated knockdown of SS18-SSX impairs CREB phosphorylation in SySa cells. Inhibition of CREB activity reduces downstream target expression, accompanied by suppression of SySa cell proliferation and induction of apoptosis invitro and in vivo.

Conclusion

In conclusion, our data underline an essential role of CREB in SySa tumorigenesis and provides evidence for molecular targeted therapies.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13402-022-00673-w.

Intracranial hemorrhage in COVID-19 patients during extracorporeal membrane oxygenation for acute respiratory failure: a nationwide register study report

Background

In severe cases, SARS-CoV-2 infection leads to acute respiratory distress syndrome (ARDS), often treated by extracorporeal membrane oxygenation (ECMO). During ECMO therapy, anticoagulation is crucial to prevent device-associated thrombosis and device failure, however, it is associated with bleeding complications. In COVID-19, additional pathologies, such as endotheliitis, may further increase the risk of bleeding complications. To assess the frequency of bleeding events, we analyzed data from the German COVID-19 autopsy registry (DeRegCOVID).

Methods

The electronic registry uses a web-based electronic case report form. In November 2021, the registry included N = 1129 confirmed COVID-19 autopsy cases, with data on 63 ECMO autopsy cases and 1066 non-ECMO autopsy cases, contributed from 29 German sites.

Findings

The registry data showed that ECMO was used in younger male patients and bleeding events occurred much more frequently in ECMO cases compared to non-ECMO cases (56% and 9%, respectively). Similarly, intracranial bleeding (ICB) was documented in 21% of ECMO cases and 3% of non-ECMO cases and was classified as the immediate or underlying cause of death in 78% of ECMO cases and 37% of non-ECMO cases. In ECMO cases, the three most common immediate causes of death were multi-organ failure, ARDS and ICB, and in non-ECMO cases ARDS, multi-organ failure and pulmonary bacterial ± fungal superinfection, ordered by descending frequency.

Interpretation

Our study suggests the potential value of autopsies and a joint interdisciplinary multicenter (national) approach in addressing fatal complications in COVID-19.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-022-03945-x.

First report from the German COVID-19 autopsy registry

Background

Autopsies are an important tool in medicine, dissecting disease pathophysiology and causes of death. In COVID-19, autopsies revealed e.g., the effects on pulmonary (micro)vasculature or the nervous system, systemic viral spread, or the interplay with the immune system. To facilitate multicentre autopsy-based studies and provide a central hub supporting autopsy centres, researchers, and data analyses and reporting, in April 2020 the German COVID-19 Autopsy Registry (DeRegCOVID) was launched.

Methods

The electronic registry uses a web-based electronic case report form. Participation is voluntary and biomaterial remains at the respective site (decentralized biobanking). As of October 2021, the registry included N=1129 autopsy cases, with 69271 single data points including information on 18674 available biospecimens gathered from 29 German sites.

Findings

In the N=1095 eligible records, the male-to-female ratio was 1·8:1, with peaks at 65-69 and 80-84 years in males and >85 years in females. The analysis of the chain of events directly leading to death revealed COVID-19 as the underlying cause of death in 86% of the autopsy cases, whereas in 14% COVID-19 was a concomitant disease. The most common immediate cause of death was diffuse alveolar damage, followed by multi-organ failure. The registry supports several scientific projects, public outreach and provides reports to the federal health authorities, leading to legislative adaptation of the German Infection Protection Act, facilitating the performance of autopsies during pandemics.

Interpretation

A national autopsy registry can provide multicentre quantitative information on COVID-19 deaths on a national level, supporting medical research, political decision-making and public discussion.

Funding

German Federal Ministries of Education and Research and Health.

Hintergrund: Obduktionen sind ein wichtiges Instrument in der Medizin, um die Pathophysiologie von Krankheiten und Todesursachen zu untersuchen. Im Rahmen von COVID-19 wurden durch Obduktionen z.B. die Auswirkungen auf die pulmonale Mikrovaskulatur, das Nervensystem, die systemische Virusausbreitung, und das Zusammenspiel mit dem Immunsystem untersucht. Um multizentrische, auf Obduktionen basierende Studien zu erleichtern und eine zentrale Anlaufstelle zu schaffen, die Obduktionszentren, Forscher sowie Datenanalysen und -berichte unterstützt, wurde im April 2020 das deutsche COVID-19-Autopsieregister (DeRegCOVID) ins Leben gerufen.

Methoden: Das elektronische Register verwendet ein webbasiertes elektronisches Fallberichtsformular. Die Teilnahme ist freiwillig und das Biomaterial verbleibt am jeweiligen Standort (dezentrales Biobanking). Im Oktober 2021 umfasste das Register N=1129 Obduktionsfälle mit 69271 einzelnen Datenpunkten, die Informationen über 18674 verfügbare Bioproben enthielten, die von 29 deutschen Standorten gesammelt wurden.

Ergebnisse: In den N=1095 ausgewerteten Datensätzen betrug das Verhältnis von Männern zu Frauen 1,8:1 mit Spitzenwerten bei 65-69 und 80-84 Jahren bei Männern und >85 Jahren bei Frauen. Die Analyse der Sequenz der unmittelbar zum Tod führenden Ereignisse ergab, dass in 86 % der Obduktionsfälle COVID-19 die zugrunde liegende Todesursache war, während in 14 % der Fälle COVID-19 eine Begleiterkrankung war. Die häufigste unmittelbare Todesursache war der diffuse Alveolarschaden, gefolgt von Multiorganversagen. Das Register unterstützt mehrere wissenschaftliche Projekte, die Öffentlichkeitsarbeit und liefert Berichte an die Bundesgesundheitsbehörden, was zu einer Anpassung des deutschen Infektionsschutzgesetzes führte und die Durchführung von Obduktionen in Pandemien erleichtert.

Interpretation: Ein nationales Obduktionsregister kann multizentrische quantitative Informationen über COVID-19-Todesfälle auf nationaler Ebene liefern und damit die medizinische Forschung, die politische Entscheidungsfindung und die öffentliche Diskussion unterstützen.

Finanzierung: Bundesministerien für Bildung und Forschung und für Gesundheit.

The association of Health-Related Quality of Life and 1-year-survival in sarcoma patients—results of a Nationwide Observational Study (PROSa)

Background

Sarcomas are rare cancers of high heterogeneity. Health-Related Quality of Life (HRQoL) has been shown to be a prognostic factor for survival in other cancer entities but it is unclear whether this applies to sarcoma patients.

Patients and methods

HRQoL was prospectively assessed in adult sarcoma patients from 2017 to 2020 in 39 German recruiting sites using the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30). Vital status was ascertained over the course of 1 year. HRQoL domains were analysed by multivariable cox-regressions including clinical and socio-economic risk factors.

Results

Of 1102 patients, 126 (11.4%) died during follow-up. The hazard ratio (HR) for global health was 0.73 per 10-point increase (95% confidence interval (CI) 0.64–0.85). HR for the HRQoL-summary score was 0.74 (CI 0.64–0.85) and for physical functioning 0.82 (CI 0.74–0.89). There was also evidence that fatigue (HR 1.17, CI 1.10–1.25), appetite loss (HR 1.15, CI 1.09–1.21) and pain (HR 1.14, CI 1.08–1.20) are prognostic factors for survival.

Conclusion

Our study adds sarcoma-specific evidence to the existing data about cancer survival in general. Clinicians and care-givers should be aware of the relations between HRQoL and survival probability and include HRQoL in routine assessment.

Fibrinogen-like protein 2 in gastrointestinal stromal tumour

Gastrointestinal stromal tumour (GIST), the most common sarcoma of the gastrointestinal tract, can be treated effectively with tyrosine kinase inhibitors, such as imatinib. Cancer immune therapy has limited efficacy, and little is known about the immune suppressive factors in GISTs. Fibrinogen‐like protein 2 (FGL2) is expressed either as a membrane‐associated protein or as a secreted soluble protein that has immune suppressive functions. We found that GISTs expressed FGL2 mRNA highly compared to other types of cancer in a large human cancer transcriptome database. GIST expressed FGL2 frequently also when studied using immunohistochemistry in two large clinical series, where 333 (78%) out of the 425 GISTs were FGL2 positive. The interstitial cells of Cajal, from which GISTs may originate, expressed FGL2. FGL2 expression was associated with small GIST size, low mitotic counts and low tumour‐infiltrating lymphocyte (TIL) counts. Patients whose GIST expressed FGL2 had better recurrence‐free survival than patients whose GIST lacked expression. Imatinib upregulated FGL2 in GIST cell lines, and the patients with FGL2‐negative GIST appeared to benefit most from long duration of adjuvant imatinib. We conclude that GISTs express FGL2 frequently and that FGL2 expression is associated with low TIL counts and favourable survival outcomes.

[Abdominal soft tissue tumors]

Gastrointestinal stromal tumors are the most common mesenchymal tumors in the abdomen and occur in Germany with an incidence of 10 to 15 cases per million inhabitants. Clear identification and characterization are of major importance for the prognosis and therapy of patients. Similarly, they have to be differentiated from other mesenchymal neoplasias such as leiomyomatous, neurogenic, adipocytic, and fibroblastic tumors. Additionally, the number of translocation positive neoplasias is increasing, requiring the use of adequate molecular assays. The aim of this paper is to give practical advice for their identification. Reference pathology is one possibility to support the correct diagnosis.

[Update on collaborative autopsy-based research in German pathology, neuropathology, and forensic medicine]

BACKGROUND

Autopsies are a valuable tool for understanding disease, including COVID-19.

MATERIALS AND METHODS

The German Registry of COVID-19 Autopsies (DeRegCOVID), established in April 2020, serves as the electronic backbone of the National Autopsy Network (NATON), launched in early 2022 following DEFEAT PANDEMIcs.

RESULTS

The NATON consortium's interconnected, collaborative autopsy research is enabled by an unprecedented collaboration of 138 individuals at more than 35 German university and non-university autopsy centers through which pathology, neuropathology, and forensic medicine autopsy data including data on biomaterials are collected in DeRegCOVID and tissue-based research and methods development are conducted. More than 145 publications have now emerged from participating autopsy centers, highlighting various basic science and clinical aspects of COVID-19, such as thromboembolic events, organ tropism, SARS-CoV‑2 detection methods, and infectivity of SARS-CoV-2 at autopsy.

CONCLUSIONS

Participating centers have demonstrated the high value of autopsy and autopsy-derived data and biomaterials to modern medicine. The planned long-term continuation and further development of the registry and network, as well as the open and participatory design, will allow the involvement of all interested partners.

Multiparametric Magnetic Resonance Imaging for Immediate Target Hit Assessment of CD13-Targeted Tissue Factor tTF-NGR in Advanced Malignant Disease

Simple Summary

Since the knowledge of tumor biology has advanced, a variety of targeted therapies has been developed. These do not immediately affect the tumor size, so optimized oncological imaging is needed. In this phase I study of patients with advanced malignant disease, a multiparametric imaging approach was used to assess changes in tumor perfusion after vessel-occluding therapy with the CD13 targeted truncated tissue factor with a C-terminal NGR-peptide. It comprises different sequences and the use of two different contrast media, ferucarbotran and gadobutrol. This multiparametric MRI protocol enables assessing the therapy effectiveness as early as five hours after therapy initiation.

Abstract

Early assessment of target hit in anti-cancer therapies is a major task in oncologic imaging. In this study, immediate target hit and effectiveness of CD13-targeted tissue factor tTF-NGR in patients with advanced malignant disease enrolled in a phase I trial was assessed using a multiparametric MRI protocol. Seventeen patients with advanced solid malignancies were enrolled in the trial and received tTF-NGR for at least one cycle of five daily infusions. Tumor target lesions were imaged with multiparametric MRI before therapy initiation, five hours after the first infusion and after five days. The imaging protocol comprised ADC, calculated from DWI, and DCE imaging and vascular volume fraction (VVF) assessment. DCE and VVF values decreased within 5 h after therapy initiation, indicating early target hit with a subsequent decrease in tumor perfusion due to selective tumor vessel occlusion and thrombosis induced by tTF-NGR. Simultaneously, ADC values increased at five hours after tTF-NGR administration. In four patients, treatment had to be stopped due to an increase in troponin T hs, with subsequent anticoagulation. In these patients, a reversed effect, with DCE and VVF values increasing and ADC values decreasing, was observed after anticoagulation. Changes in imaging parameters were independent of the mean vessel density determined by immunohistochemistry. By using a multiparametric imaging approach, changes in tumor perfusion after initiation of a tumor vessel occluding therapy can be evaluated as early as five hours after therapy initiation, enabling early assessment of target hit.

Intensity-modulated Radiotherapy in Patients With Aggressive Extranodal Non-Hodgkin Lymphoma of the Head and Neck

BACKGROUND/AIM

Image-guided intensity-modulated radiotherapy (IG-IMRT) is increasingly being used to treat patients with head and neck malignancies. This analysis compared conventional radiotherapy (CRT) and IMRT outcomes for head and neck aggressive extranodal non-Hodgkin lymphomas (EN-NHL).

PATIENTS AND METHODS

Forty-eight patients who underwent irradiation between 2005 and 2019 were identified.

RESULTS

The median follow-up was 42 months. Patients treated with IMRT experienced higher overall responde rate than patients who received 3DCRT (85% vs. 73%, p=0.4). There was non-significant longer survival following IMRT compared with 3DCRT in terms of 5-year OS (p=0.16). Complete responders after primary treatments had a significantly higher 5-year progression-free (p<0.001) and overall survival (p=0.003) in comparison with those without a complete response. Regarding toxicities, IMRT was associated with less acute and chronic adverse events.

CONCLUSION

IG-IMRT following systemic therapy seems to be associated with a favorable survival and toxicity profile in patients with EN-NHL.

The novel KIT exon 11 germline mutation K558N is associated with gastrointestinal stromal tumor, mastocytosis, and seminoma development

Familial gastrointestinal stromal tumors (GIST) are dominant genetic disorders that are caused by germline mutations of the type III receptor tyrosine kinase KIT. While sporadic mutations are frequently found in mastocytosis and GISTs, germline mutations of KIT have only been described in 39 families until now. We detected a novel germline mutation of KIT in exon 11 (p.Lys-558-Asn; K558N) in a patient from a kindred with several GISTs harboring different secondary somatic KIT mutations. Structural analysis suggests that the primary germline mutation alone is not sufficient to release the autoinhibitory region of KIT located in the transmembrane domain. Instead, the KIT kinase module becomes constitutively activated when K558N combines with different secondary somatic mutations. The identical germline mutation in combination with an additional somatic KIT mutation was detected in a second patient of the kindred with seminoma while a third patient within the family had a cutaneous mastocytosis. These findings suggest that the K558N mutation interferes with the juxtamembranous part of KIT, since seminoma and mastocystosis are usually not associated with exon 11 mutations.

Efficacy thresholds for clinical trials with advanced or metastatic leiomyosarcoma patients: A European Organisation for Research and Treatment of Cancer Soft Tissue and Bone Sarcoma Group meta-analysis based on a literature review for soft-tissue sarcomas

BACKGROUND

In 2002, the European Organisation for Research and Treatment of Cancer Soft Tissue and Bone Sarcoma Group reported well-established values for conducting phase II trials for soft-tissue sarcomas. An update is provided for leiomyosarcoma (LMS).

MATERIALS AND METHODS

Clinical trials with advanced or metastatic LMS were identified via literature review in PubMed (published 2003-2018, ≥10 adult LMS patients). End-points were 3- and 6-month progression-free survival rates (PFSR-3m and PFSR-6m). When estimates could not be derived from publications, data requests were sent out. Treatments were classified as recommended (R-T) or non-recommended (NR-T) according to the ESMO 2018 guidelines. A random effects meta-analysis was used to pool trial-specific estimates for first-line (1L) or pre-treated (2L+) patients separately. The ESMO Magnitude of Clinical Benefit Scale was used to guide the treatment effect to target in future trials.

RESULTS

From 47 studies identified, we obtained information on 7 1L and 16 2L+ trials for 1500 LMS patients. Overall, in 1L, PFSR-3m and PFSR-6m were 74% (95% confidence interval [CI] 64-82%) and 58% (95% CI 50-66%), respectively. For 2L+, PFSR-3m was 48% (95% CI 41-54%), and PFSR-6m was 28% (95% CI 22-34%). No difference was observed between R-T and NR-T for first or later lines. Under the alternative that the true benefit amounts to a hazard ratio of 0.65, a PFSR-6m ≥70% can be considered to suggest drug activity in 1L. For 2L+, a PFSR-3m ≥62% or PFSR-6m ≥44% would suggest drug activity. Specific results are also provided for uterine LMS.

CONCLUSIONS

This work provides a new benchmark for designing phase II studies for advanced or metastatic LMS.

Abstract 2003: Oncogenic interplay of FUS-DDIT3 and YAP1 in myxoid liposarcoma

Introduction: Myxoid liposarcoma (MLS) represents the second most common subtype of liposarcoma. MLS is characterized by a chromosomal translocation t(12;16)(q13;p11) encoding a chimeric FUS-DDIT3 fusion gene. The resulting FUS-DDIT3 oncoprotein acts as a transcriptional dysregulator that was recently shown to mediate (i) IGF-IR/PI3K/AKT signaling and (ii) aberrant activation of the Hippo pathway effector YAP1 in MLS. This study was performed to analyze the functional interplay between IGF-IR/PI3K/AKT signals and aberrant YAP1 activity in MLS, aiming at a better functional understanding of MLS and the identification of specific molecular vulnerabilities.

Experimental procedures: Immunohistochemical stainings of IGF-IR, IGF-II and YAP1 were performed in a cohort of MLS specimens (n=45). To study FUS-DDIT3-dependency in vitro, SCP-1 mesenchymal stem cells stably expressing FUS-DDIT3, and MLS cell lines expressing a doxycycline-inducible shRNA against FUS-DDIT3 were employed. Interactions between the IGF-IR/PI3K/AKT and Hippo/YAP1 pathways were investigated using RNAi approaches as well as the small molecule compounds BMS-754807 and BKM120; effects were analyzed by immunoblotting and TEAD luciferase reporter assays. To determine the impact of YAP1 in FUS-DDIT3-mediated oncogenic effects, qPCR analysis and adipogenic differentiation assays were performed.

Results: Immunohistochemical analysis of human MLS tissue specimens demonstrated that expression of IGF-II and IGF-IR is associated with concomitant nuclear expression of YAP1 in a significant subset of MLS. Both, IGF-IR-dependent signals and YAP1 expression were shown to be functionally dependent on FUS-DDIT3. In MLS cell lines, inhibition of the IGF-IR/PI3K/AKT signaling cascade promoted downregulation of YAP1, accompanied by reduced TEAD transcriptional activity. Employing qPCR analyses, YAP1 was shown to co-regulate FUS-DDIT3 transcriptional targets and to be functionally involved in FUS-DDIT3-driven disruption of normal adipocytic differentiation.

Conclusions: Our study provides evidence of a complex regulatory interplay in MLS with FUS-DDIT3-driven IGF-IR/PI3K/AKT signals acting as activators of nuclear YAP1 expression. Conversely, YAP1 contributes to shape FUS-DDIT3 effects on the MLS transcriptional landscape and functionally adds to an immature non-lipogenic phenotype. Our data contribute to the understanding of MLS biology and reveal specific molecular liabilities to be considered in therapeutic approaches of MLS.

Citation Format: Ruth Berthold, Ilka Isfort, Jonas Breuer, Lorena Heinst, Thomas Kindler, Pierre Åman, Inga Grünewald, Eva Wardelmann, Thomas G. Grünewald, Florencia Cidre-Aranaz, Claudia Scholl, Stefan Fröhling, Marcel Trautmann, Wolfgang Hartmann. Oncogenic interplay of FUS-DDIT3 and YAP1 in myxoid liposarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2003.

Efficacy and safety of nivolumab and trabectedin in pretreated patients with advanced soft tissue sarcomas (STS): Preliminary results of a phase II trial of the German Interdisciplinary Sarcoma Group (GISG-15, NitraSarc) for the non-L sarcoma cohort

11545

Background: Single-agent PD-1 inhibitors have modest activity in the treatment of most STS. Potential strategies to increase efficacy include combination therapies targeting the tumor microenvironment. Considering that apart from direct growth inhibition and death of malignant cells, trabectedin (Tr) also induces macrophage depletion and/or different immunologic effects, suggesting a possible synergistic effect of combined Tr plus anti-PD-1 treatment. We therefore aimed to evaluate the efficacy and safety of combined Tr and nivolumab (Ni) as a second-line treatment in STS. Methods: The prospective, explorative, two group, non-randomized phase II NiTraSarc trial enrolled pretreated patients (pt) with advanced STS (Group A: lipo- or leiomyosarcomas, Group B: non-L-sarcomas). Pt were initially treated with 3 cycles of Tr 1.5 mg/m2, followed by the combination of Tr 1.5 mg/m2 + Ni 240 mg (“late combination cohort” (LCC)) for up to 16 cycles. After positive results of a preplanned interim analysis, pt received the combination therapy starting with cycle 2 (“early combination cohort” (ECC)). 92 pt were recruited to the trial (55 in Group A, 37 in Group B). Primary efficacy endpoint is progression-free survival rate after 6 months (PFSR6) according to RECIST v.1.1. This is a first analysis of the primary efficacy endpoint in Group B based on a modified intention-to-treat (mITT) population of evaluable 36 pt: 23 and 13 pt from the LCC and ECC, respectively. Results: The most common Group B subtypes comprised undifferentiated pleomorphic/not otherwise specified sarcoma (UPS/NOS, 13pt) and fibromyxoid sarcoma (FMS, 6pt). After a median follow-up of 5 months (m) PFSR6 was 13.9% for all pt, 8.7% in LCC and 23.1% in ECC. Median duration of disease stabilization (DoDS) was 4m in all pt, the LCC and the ECC. Two pt had a partial response (PR), 10 had disease stabilization (SD), while 13 pt progressed, and 11 had missing data. By subtype: PR- UPS/NOS=2 (DoDS 12.7m/12.5m). SD: UPS/NOS=3, epithelioid=2, synovial=2, FMS=1, fibrosarcoma=1, other=1. All 36 pt experienced at least one adverse event (AE) reaching a total of 579 AEs, 141 (24.4%) of which were considered to be grade ≥3 treatment-related AEs. The main grade ≥3 AEs were: leukopenia (47.2% of pt), neutropenia (41.7% of pt), thrombocytopenia (33.3% of pt), increased ALT (30.6% of pt), and anemia (27.8% of pt). Conclusions: Tr+Ni was well tolerated and showed activity in at least some patients with non-L-sarcomas (mostly UPS/NOS) especially in the ECC. Analyses of the collected data, including PD-L1 expression profile, with the goal to establish whether Tr+Ni should be further pursued in these patients, are ongoing. ClinicalTrials.gov Identifier: NCT03590210; EudraCT: 2017-001083-38. Clinical trial information: NCT03590210.

Dose escalation and expansion phase I studies with the tumour-targeting antibody-tumour necrosis factor fusion protein L19TNF plus doxorubicin in patients with advanced tumours, including sarcomas

BACKGROUND

L19TNF is a recombinant fusion protein composed of a human antibody fragment and human tumour necrosis factor. L19TNF targets the EDB domain of oncofetal fibronectin highly expressed in tumour vasculature and induces tumour remission in mouse tumours. We summarise two phase I trials testing a combination of L19TNF with doxorubicin in patients with solid tumours, particularly soft tissue sarcomas (STS).

PATIENTS AND METHODS

The first study, an open-label, dose-escalation and expansion phase I study of L19TNF plus doxorubicin, enrolled 27 patients. Three cohorts (10.4-17 μg/kg L19TNF) of patients received L19TNF intravenously at days 1, 3, and 5 and doxorubicin (75 mg/m², then 60 mg/m²) on day 1 every 3 weeks. The expansion cohort enrolled patients with STS. The second study tried to re-escalate the doxorubicin dose to 75 mg/m² with 13 μg/kg L19TNF. Among primary objectives was the establishment of a recommended dose (RD).

RESULTS

The combination was safely applicable. Dose-limiting toxicity occurred either at 17 μg/kg L19TNF or at 75 mg/m² doxorubicin. RD is 13 μg/kg L19TNF plus 60 mg/m² doxorubicin. In 15 STS patients of the extension cohort evaluable for efficacy, antitumour activity was observed with complete remission in 1, partial remission in 1 and minor tumour shrinkage in 7 patients. The median overall survival for this heavily pretreated cohort was 14.9 months.

CONCLUSION

L19TNF can be safely applied in combination with doxorubicin and induces encouraging tumour remissions in patients with soft tissue sarcomas.

Utilization of Interdisciplinary Tumor Boards for Sarcoma Care in Germany: Results from the PROSa Study

BACKGROUND

Data on institutional structures of sarcoma care in Germany are scarce. The utilization of an interdisciplinary tumor board (IDTB) is an essential part of modern cancer care. We investigated to which extent and when IDTB are used in sarcoma care. We hypothesized that IDTB before treatment initiation were used more often at certified cancer centers and at high-volume centers and that IDTB utilization increased over time.

METHODS

From 2017 to 2020 we conducted a prospective cohort study, undertaking major efforts to include the whole spectrum of sarcoma treatment facilities. To analyze potential predictors of IDTB utilization, we calculated multivariable logistic regressions.

RESULTS

Patients and survivors (n = 1,309) from 39 study centers (22 tertiary referral hospitals, 9 other hospitals, and 8 office-based practices) participated; 88.3% of the patients were discussed at some stage of their disease in an IDTB (56.1% before treatment, 78% after therapy, and 85.9% in metastatic disease). Hypotheses were confirmed regarding the utilization of IDTB in certified cancer centers (vs. all others: OR = 5.39; 95% CI 3.28-8.85) and the time of diagnosis (2018/2019 vs. until 2013: OR = 4.95; 95% CI 2.67-9.21).

CONCLUSION

Our study adds to the evidence regarding the institutional structures of sarcoma care in Germany. Utilization of a tumor board before therapy seems to be in an implementation process that is making progress but is far from complete. Certification is a possible tool to accelerate this development.

Genomic characterization of small cell carcinomas of the uterine cervix

Small cell carcinoma (SCC) of the uterine cervix is a rare and aggressive form of neuroendocrine carcinoma, which resembles small cell lung cancer (SCLC) in its histology and poor survival rate. Here, we sought to define the genetic underpinning of SCCs of the uterine cervix and compare their mutational profiles with those of human papillomavirus (HPV)‐positive head and neck squamous cell carcinomas, HPV‐positive cervical carcinomas, and SCLCs using publicly available data. Using a combination of whole‐exome and targeted massively parallel sequencing, we found that the nine uterine cervix SCCs, which were HPV18‐positive (n = 8) or HPV16‐positive (n = 1), harbored a low mutation burden, few copy number alterations, and other than TP53 in two cases no recurrently mutated genes. The majority of mutations were likely passenger missense mutations, and only few affected previously described cancer‐related genes. Using RNA‐sequencing, we identified putative viral integration sites on 18q12.3 and on 8p22 in two SCCs of the uterine cervix. The overall nonsilent mutation rate of uterine cervix SCCs was significantly lower than that of SCLCs, HPV‐driven cervical adeno‐ and squamous cell carcinomas, or HPV‐positive head and neck squamous cell carcinomas. Unlike SCLCs, which are reported to harbor almost universal TP53 and RB1 mutations and a dominant tobacco smoke‐related signature 4, uterine cervix SCCs rarely harbored mutations affecting these genes (2/9, 22% TP53; 0% RB1) and displayed a dominant aging (67%) or APOBEC mutational signature (17%), akin to HPV‐driven cancers, including cervical adeno‐ and squamous cell carcinomas and head and neck squamous cell carcinomas. Taken together, in contrast to SCLCs, which are characterized by highly recurrent TP53 and RB1 alterations, uterine cervix SCCs were positive for HPV leading to inactivation of the suppressors p53 and RB, suggesting that these SCCs are convergent phenotypes.

[New in the current WHO classification (2020) for soft tissue sarcomas]

The current WHO classification for tumors of soft tissue and bone includes numerous new entities, most often defined by novel molecular findings. In this article, we present translocation-positive tumors to broaden the spectrum of monomorphic mesenchymal neoplasias. The undifferentiated small round cell sarcomas are now assembled in their own separate chapter to underline their occurrence in both soft tissue and bone, emphasizing their morphologic, molecular, and biologic differences. Another interesting new group are tumors with GLI1 activation, which, however, have not yet been included into the WHO classification. NTRK-driven tumors present with a potential therapeutic target for several established inhibitors. Finally, there have been novel findings in rhabdomyosarcomas allowing more precise subtyping associated with different biological behavior.

Survival Outcomes Associated With 3 Years vs 1 Year of Adjuvant Imatinib for Patients With High-Risk Gastrointestinal Stromal Tumors: An Analysis of a Randomized Clinical Trial After 10-Year Follow-up

Importance

Adjuvant imatinib is associated with improved recurrence-free survival (RFS) when administered after surgery to patients with operable gastrointestinal stromal tumor (GIST), but its influence on overall survival (OS) has remained uncertain.

Objective

To evaluate the effect of adjuvant imatinib on OS of patients who have a high estimated risk for GIST recurrence after macroscopically complete surgery.

Design, Setting, and Participants

In this open-label, randomized (1:1), multicenter phase 3 clinical trial conducted in Finland, Germany, Norway, and Sweden, 400 patients who had undergone macroscopically complete surgery for GIST with a high estimated risk for recurrence according to the modified National Institutes of Health Consensus Criteria were enrolled between February 2004 and September 2008. Data for this follow-up analysis were analyzed from September to November, 2019.

Interventions

Imatinib 400 mg/d administered orally for either 12 months or 36 months after surgery.

Main Outcomes And Measures

The primary end point was RFS; the secondary objectives included OS and treatment safety.

Results

The intention-to-treat cohort consisted of 397 patients (12-month group, 199; 36-month group, 198; 201 men and 196 women; median [IQR] age, 62 (51-69) years and 60 (51-67) years, during a median follow-up time of 119 months after the date of randomization, 194 RFS events and 96 OS events were recorded in the intention-to-treat population. Five-year and 10-year RFS was 71.4% and 52.5%, respectively, in the 36-month group and 53.0% and 41.8% in the 12-month group (hazard ratio [HR], 0.66; 95% CI, 0.49-0.87; P = .003). In the 36-month group, 5-year OS and 10-year OS rates were 92.0% and 79.0%, respectively, and in the 12-month group 85.5% and 65.3% (HR, 0.55; 95% CI, 0.37-0.83; P = .004). The results were similar in the efficacy population, from which 15 patients who did not have GIST in central pathology review and 24 patients who had intra-abdominal metastases removed at surgery were excluded (36-month group, 10-year OS 81.6%; 12-month group, 66.8%; HR, 0.50; 95% CI, 0.32-0.80; P = .003). No new safety signals were detected.

Conclusions and Relevance

Three years of adjuvant imatinib is superior in efficacy compared with 1 year of imatinib. Approximately 50% of deaths may be avoided during the first 10 years of follow-up after surgery with longer adjuvant imatinib treatment.

Trial Registration

ClinicalTrials.gov Identifier: NCT00116935.