Abstract 2690
Background
GIST in older adults and in children are well-known entities, but this is not the case for AYA patients with GIST. Typically, GIST in children (70% female) rarely show mutations in KIT or platelet-derived growth factor receptor (PDGFR) (<15%), are often Succinate Dehydrogenase (SDH) deficient, are almost always located in the stomach (90%) and have a relatively indolent course of disease. The typical adult GIST (about 50% female) has mutations in KIT (75%) or PDGFR (15%), stomach as main location and an overall 5-years survival of 65% (SEER data). As data on AYA with GIST are very limited, we aimed to study the clinical and genetic characteristics and outcome of this specific group.
Methods
AYA GIST patients (18-40 years at diagnosis) diagnosed between 2009-2019 and registered in the Dutch GIST Registry (DGR) were included. Patients without mutations in KIT/PDGFR/BRAF and SDH deficiency (by immunohistochemistry) were considered quadruple wildtype (WT). Overall survival (OS) was estimated using Kaplan-Meier method. Furthermore, two subgroups were compared: 18-29 years vs. 30-40 years (Chi-square, Fisher’s exact, Mann-Whitney U test).
Results
From 1011 patients in the DGR, 52 AYA patients (5%) were identified: 54% male, median age 35 years. Main primary tumor locations were stomach (46%) and small intestine (46%). Four AYA patients had a known genetic predisposition: 2 Neurofibromatosis 1 (NF1), 1 Carney Triad, 1 KIT exon 11 germline mutation. GIST genetic profiles were reported as KIT mutation 64%, PDGFR mutation 6%, KIT/PDGFR WT 6%, quadruple WT 8%, SDH deficient 6% and NF1 associated 4%. At diagnosis, 42% had high-risk GIST and 13% metastatic disease.
With a median follow-up of 43 months (0-113), median OS for all patients was 8.9 years with a 5-year survival of 85%. No significant differences were found between the two subgroups with regard to gender, location, size, morphology, risk classification and mutation status.
Conclusions
GIST presenting at AYA age is rare. AYA GIST differ from the well-known paediatric GIST, but are also not fully similar to the typical adult GIST. In our series a remarkable high percentage of small intestine GIST and high-risk tumours were observed, 30% non-KIT/PDGFR mutations and a relatively good survival.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The Netherlands Cancer Institute.
Funding
An unrestricted research grant for the Dutch GIST Registry was received from Novartis, Bayer and Pfizer.
Disclosure
I.M.E. Desar: Research grant / Funding (institution): Novartis; Advisory / Consultancy, advisory board: Eisai; Advisory / Consultancy, advisory board: Lilly. R.H.J. Mathijssen: Research grant / Funding (institution), Travel / Accommodation / Expenses: Astellas; Research grant / Funding (institution): Bayer; Research grant / Funding (institution): Boehringer; Research grant / Funding (institution): Cristal Therapeutics; Honoraria (institution), Research grant / Funding (institution): Novartis; Research grant / Funding (institution): Pamgene; Research grant / Funding (institution), Travel / Accommodation / Expenses: Pfizer; Research grant / Funding (institution): Roche; Research grant / Funding (institution): Sanofi; Honoraria (institution): Servier. N. Steeghs: Research grant / Funding (institution): AstraZeneca/MedImmune; Research grant / Funding (institution): Bayer; Research grant / Funding (institution): Bristol-Myers Squibb; Research grant / Funding (institution): Novartis; Research grant / Funding (institution): GlaxoSmithKline; Research grant / Funding (institution): Pfizer; Research grant / Funding (institution): Roche; Research grant / Funding (institution): Genentech/Roche; Research grant / Funding (institution): Boehringer Ingelheim; Research grant / Funding (institution): Blueprint Medicines; Research grant / Funding (institution): AB science; Research grant / Funding (institution): Deciphera; Research grant / Funding (institution): Genentech; Research grant / Funding (institution): Merck Sharp & Dohme; Research grant / Funding (institution): Amgen; Research grant / Funding (institution): Lilly; Research grant / Funding (institution): Incyte; Research grant / Funding (institution): Merus. W.T.A. van der Graaf: Research grant / Funding (institution): Novartis; Advisory / Consultancy: Bayer. All other authors have declared no conflicts of interest.
Resources from the same session
3690 - PD-L1 expression in resected undifferentiated pleomorphic sarcoma and its clinical implications
Presenter: Kyoungmin Lee
Session: Poster Display session 1
Resources:
Abstract
2013 - PD-L1 expression as a potential therapeutic target and prognostic biomarker in well-differentiated and dedifferentiated liposarcoma.
Presenter: Heejung Chae
Session: Poster Display session 1
Resources:
Abstract
5021 - Soft tissue sarcomas express a distinct mRNA immune profile
Presenter: Viktor Grünwald
Session: Poster Display session 1
Resources:
Abstract
3029 - The molecular landscape of fusion genes in endometrial stromal sarcomas include three nosological entities with different natural history
Presenter: Mehdi Brahmi
Session: Poster Display session 1
Resources:
Abstract
3914 - Clinical validation of a novel assay for the detection of diagnostic alterations in sarcomas
Presenter: Lauren Mc Connell
Session: Poster Display session 1
Resources:
Abstract
1912 - A prospective correlative trial of personalized patient-derived xenograft (PDX) as avatars for drug therapy in patients with metastatic or recurrent soft tissue sarcomas (STS).
Presenter: Kanan Alshammari
Session: Poster Display session 1
Resources:
Abstract
5097 - Fusion of immortalized myoblasts induces genomic instability that drives tumor development and progression.
Presenter: Candice Merle
Session: Poster Display session 1
Resources:
Abstract
1383 - let-7a suppress Ewing sarcoma CSCs' malignant phenotype through forms a positive feedback regulation loop with lin28 via STAT3
Presenter: Xu Jiang
Session: Poster Display session 1
Resources:
Abstract
3386 - Myoepithelial Tumors of Soft Tissues and Extraskeletal Myxoid Chondrosarcomas feature a distinct transcriptional pattern
Presenter: Dominga Racanelli
Session: Poster Display session 1
Resources:
Abstract
1844 - In Vivo Efficacy and Enhanced Tumor Accumulation of Liposomal Vinorelbine (TLC178) in Human Sarcoma Xenograft Mice Model
Presenter: Wan-ni Yu
Session: Poster Display session 1
Resources:
Abstract