Chiara Sartor

DOG1 and CD117 are the antibodies of choice in the diagnosis of gastrointestinal stromal tumours.

Novelli M, Rossi S, Rodriguez‐Justo M, Taniere P, Seddon B, Toffolatti L, Sartor C, Hogendoorn P C W, Sciot R, Van Glabbeke M, Verweij J, Blay J Y, Hohenberger P, Flanagan A & Dei Tos A P
(2010) Histopathology57, 259–270
DOG1 and CD117 are the antibodies of choice in the diagnosis of gastrointestinal stromal tumours

Molecular and clinicopathologic characterization of gastrointestinal stromal tumors (GISTs) of small size.

Although Gastrointestinal stromal tumors (GISTs) affect about 0.0014% of the population, GISTs smaller than 1 cm (microGISTs) are detectable in about 20% to 30% of elderly individuals. This suggests that microGISTs likely represent premalignant precursors that evolve only in a minute fraction of cases toward overt GISTs. We sought histopathologic and molecular explanations for the infrequent clinical progression in small GISTs. To investigate the mechanisms of GIST progression and identify subsets with differential malignant potential, we carried out a thorough characterization of 170 GISTs <2 cm and compared their KIT/PDGFRA status with overt GISTs. The proliferation was lower in microGISTs compared with GISTs from 1 to 2 cm (milliGISTs). In addition, microGISTs were more frequently incidental, gastric, spindle, showed an infiltrative growth pattern, a lower degree of cellularity, and abundant sclerosis. The progression was limited to 1 ileal and 1 rectal milliGISTs. KIT/PDGFRA mutations were detected in 74% of the cases. The overall frequency of KIT/PDGFRA mutation and, particularly, the frequency of KIT exon 11 mutations was significantly lower in small GISTs compared with overt GISTs. Five novel mutations, 3 in KIT (p.Phe506Leu, p.Ser692Leu, p.Glu695Lys) 2 in PDGFRA (p.Ser847X, p.Ser667Pro), plus 4 double mutations were identified. Small GISTs share with overt GIST KIT/PDGFRA mutation. Nevertheless, microGISTs display an overall lower frequency of mutations, particularly canonical KIT mutations, and also carry rare and novel mutations. These molecular features, together with the peculiar pathologic characteristics, suggest that the proliferation of these lesions is likely sustained by weakly pathogenic molecular events, supporting the epidemiologic evidence that microGISTs are self-limiting lesions.

Multiple Primary Sporadic Gastrointestinal Stromal Tumors in the Adult: An Underestimated Entity

Purpose: Gastrointestinal stromal tumors (GIST) are commonly regarded as solitary tumors. The occurrence of multiple lesions is considered an extraordinary event restricted to pediatric GISTs and rare hereditary conditions. Beyond these well-defined situations, the presentation of multiple synchronous lesions is commonly viewed as the result of the metastatic spreading of a single primary GIST. Based on this axiom, patients with multifocal disease are classified as advanced stage and treated as such. Whether, indeed, the detection of several lesions in sporadic adult GIST patients may be suggestive of phenomena of tumor multiplicity still needs to be clarified. Experimental Design: From a multicentric series of 442 consecutive cases, 26 of which with advanced disease, we selected 5 patients who presented up to three distinct GIST nodules. Five additional cases with similar characteristics were also contributed by two other institutions. The clonal relationship between the synchronous lesions was assessed by comparing KIT/PDGFRA mutation and microsatellite pattern. Results: An independent origin of the synchronous lesions was established in 6 of 10 cases. Notably, in one patient, one lesion arose in the peritoneum, which is ordinarily regarded as a site of metastasis. Conclusions: Our data indicate that a significant fraction of GIST patients with multifocal presentation are actually affected by multiple primary tumors, suggesting that mesenchymal GIST precursor cells of these individuals are somehow primed to transformation. Thus, in the presence of multifocal GIST manifestations, an accurate characterization of the different tumor sites should be undertaken for a proper patient staging and therapy planning.

Prexasertib, a Chk1/Chk2 inhibitor, increases the effectiveness of conventional therapy in B-/T- cell progenitor acute lymphoblastic leukemia

During the last few years many Checkpoint kinase 1/2 (Chk1/Chk2) inhibitors have been developed for the treatment of different type of cancers. In this study we evaluated the efficacy of the Chk 1/2 inhibitor prexasertib mesylate monohydrate in B-/T- cell progenitor acute lymphoblastic leukemia (ALL) as single agent and in combination with other drugs. The prexasertib reduced the cell viability in a dose and time dependent manner in all the treated cell lines. The cytotoxic activity was confirmed by the increment of apoptotic cells (Annexin V/Propidium Iodide staining), by the increase of γH2A.X protein expression and by the activation of different apoptotic markers (Parp-1 and pro-Caspase3 cleavage). Furthermore, the inhibition of Chk1 changed the cell cycle profile. In order to evaluate the chemo-sensitizer activity of the compound, different cell lines were treated for 24 and 48 hours with prexasertib in combination with other drugs (imatinib, dasatinib and clofarabine). The results from cell line models were strengthened in primary leukemic blasts isolated from peripheral blood of adult acute lymphoblastic leukemia patients. In this study we highlighted the mechanism of action and the effectiveness of prexasertib as single agent or in combination with other conventional drugs like imatinib, dasatinib and clofarabine in the treatment of B-/T-ALL.

Rationale for a pediatric-inspired approach in the adolescent and young adult population with acute lymphoblastic leukemia, with a focus on asparaginase treatment

In the last two decades great improvements have been made in the treatment of childhood acute lymphoblastic leukemia, with 5-year overall survival rates currently approaching almost 90%. In comparison, results reported in adolescents and young adults (AYAs) are relatively poor. In adults, results have improved, but are still lagging behind those obtained in children. Possible reasons for this different pattern of results include an increased incidence of unfavorable and a decreased incidence of favorable cytogenetic abnormalities in AYAs compared with children. Furthermore, in AYAs less intensive treatments (especially lower cumulative doses of drugs such as asparaginase, corticosteroids and methotrexate) and longer gaps between courses of chemotherapy are planned compared to those in children. However, although favorable results obtained in AYAs receiving pediatric protocols have been consistently reported in several international collaborative trials, physicians must also be aware of the specific toxicity pattern associated with increased success in AYAs, since an excess of toxicity may compromise overall treatment schedule intensity. Cooperative efforts between pediatric and adult hematologists in designing specific protocols for AYAs are warranted.

Revealing very small FLT3 ITD mutated clones by ultra-deep sequencing analysis has important clinical implications in AML patients

FLT3 internal tandem duplication (ITD), one of the most frequent mutations in Acute Myeloid Leukemia (AML), is reported to be an unstable marker, as it can evolve from FLT3 ITD- to ITD+ during the disease course. A single-gene sensitive mutational screening approach may be helpful for better clarifying the exact timing of mutation occurrence, especially when FLT3 ITD appears to occur late, at disease progression. We developed an amplicon-based ultra-deep-sequencing (UDS) approach for FLT3 mutational screening. We exploited this highly sensitive technology for the retrospective screening of diagnosis, relapse and follow-up samples of 5 out of 256 cytogenetically normal (CN-) AML who were FLT3 wild-type at presentation, but tested ITD+ at relapse or disease progression. Our study revealed that all patients carried a small ITD+ clone at diagnosis, which was undetectable by routine analysis (0,2–2% abundance). The dynamics of ITD+ clones from diagnosis to disease progression, assessed by UDS, reflected clonal evolution under treatment pressure. UDS appears as a valuable tool for FLT3 mutational screening and for the assessment of minimal residual disease (MRD) during follow-up, by detecting small ITD+ clones that may survive chemotherapy, evolve over time and definitely worsen the prognosis of CN-AML patients.

Recurrent Gastrointestinal Hemorrhage in Treatment with Dasatinib in a Patient Showing SMAD4 Mutation with Acute Lymphoblastic Leukemia Philadelphia Positive and Juvenile Polyposis Hereditary Hemorrhagic Telangiectasia Syndrome

We report a case of a patient affected by juvenile polyposis and hereditary hemorrhagic telangiectasia linked to a SMAD4 mutation who developed acute lymphoblastic leukemia positive for the Philadelphia chromosome translocation and with a complex karyotype. During the treatment with the tyrosine kinase inhibitor dasatinib the patient presented recurrent severe gastrointestinal hemorrhages linked to the genetic background and aggravated by thrombocytopenia.

A Case Report of Acute Myeloid Leukemia and Neurofibromatosis 1

We report a case of a 65-year old patient affected by neurofibromatosis 1, documented by the presence of germ-line mutation on the NF1 gene, who developed various hyperproliferative malignant and benign diseases. He was brought to our attention for the diagnosis of acute myeloid leukemia revealed by major fatigue and dyspnea. The disease characteristics at diagnosis were hyperleukocytosis and complex karyotype with the inversion of the chromosome 16, classifying as a high-risk leukemia. The association between leukemia and neurofibromatosis 1 is controversial and needs to be further investigated. Nevertheless, such patients present a wide number of comorbidities that make therapeutic strategies most difficult.

Efficacy of Azacitidine in the treatment of adult patients aged 65 years or older with AML

ABSTRACT Introduction: Therapy for acute myeloid leukemia (AML) in elderly populations (>65 years) is still a challenge for scientists and hematologists worldwide, and represents an urgent medical need. Notably, the identification and the recognition of molecular and epigenetic mechanisms involved in the pathogenesis of such a heterogeneous disease, are providing new tools for a more successful and ‘targeted’ approach. Azacitidine is a hypomethylating agent (HMA) with relevant activity in patients affected by myelodysplastic syndrome (MDS) and AML with low blast cells percentage (>30%), in terms of reduction of transfusion dependence, and improvement of quality of life. Areas covered: This review summarizes the mechanism of action, safety profile and efficacy of azacitidine in the field of elderly AML populations, providing up-to-date references on this subset of high-risk patients. Expert opinion: HMAs are the first successful treatment for elderly patients with high-risk MDS and are effective for some AML subtypes. Translational studies based on gene expression profiling and molecular sequencing, would be able to identify, in the near future, patients with a favorable profile of response to these compounds suggesting new potential treatment combinations also.

Posterior Reversible Encephalopathy Syndrome in a B-Cell Acute Lymphoblastic Leukemia Young Adult Patient Treated with a Pediatric-Like Chemotherapeutic Schedule

We report here the case of a young adult affected by pre B-cell acute lymphoblastic leukemia (ALL), who developed, during a pediatric-like chemotherapy consolidation schedule with high dosage of Methotrexate, a severe neurological toxicity. Clinical presentation and neuroimaging data were diagnostic for posterior reversible encephalopathy syndrome (PRES). A complete resolution was quickly obtained with medical blood pressure control and anticonvulsants administration. To the best of our knowledge, this is the first case of PRES described in the adult ALL setting. Currently, the clinical management of this aggressive disease is moving towards a pediatric-like approach also in adult patients, due to the better outcome reached with intensive chemotherapeutic regimens in children population. However, therapy-related toxicities have to be taken into account, since their onset may adversely affect patients’ clinical outcome.