RARE-06. Expanding the clinical and molecular spectrum of pituitary blastoma

Pituitary blastomas (PitB) are rare DICER1-associated tumors that occur exclusively in children < 2 years of age. They are locally aggressive tumors that are driven by a combination of germline and somatic alterations involving DICER1. Here, we report two patients with pituitary neoplasms that expand the clinical and molecular spectrum of PitB. Patient 1 presented at 10 months with diabetes insipidus and was initially diagnosed with pituitary ependymoblastoma. She received debulking, chemotherapy and focal radiation with complete response achieved, but unfortunately died at the age of 8 years due to cerebral edema. Patient 2 was a survivor of infant leukemia who was treated with chemotherapy and then further chemotherapy with cranial irradiation at relapse. The patient was then diagnosed at the age of 8 years with pituitary CNS-PNET, which was treated with craniospinal irradiation and chemotherapy, and had remained in remission for 6 years. Review of histology in both cases indicates presence of neuroendocrine lobules, primitive cells, and Rathke pouch-like glandular structures, with high Ki67, ACTH and PRAME positivity compatible with PitB. Next-generation sequencing revealed presence of two DICER1 mutations (germline frameshifting and somatic missense) in Patient 1, and one somatic missense DICER1 mutation plus loss of heterozygosity in Patient 2 (no germline alteration). Surprisingly, C19MC amplification was also detected in Patient 1. Methylation profiling confirms clustering among our samples and PitB references, but not ETMR references. MicroRNA array revealed decrease in mature microRNA expression and preferential down-regulation of 5p/3p species in tumor compared to control pituitary tissue. In all, PitBs may present with clinical and molecular characteristics not conforming with the classical descriptions. It might be prudent to consider sequencing for DICER1 alteration in pediatric pituitary tumors to facilitate diagnosis of this increasingly heterogeneous rare entity.

Carboplatin-induced renal salt-wasting syndrome in pediatric patients with intracranial germ cell tumors and concomitant diabetes insipidus

We report a case series of 14 children with intracranial germ cell tumor and concomitant central diabetes insipidus, who developed hyponatremia secondary to renal salt-wasting syndrome (RSWS) following the administration of carboplatin. Clinicians prescribing platinum-based chemotherapy for this group of patients should be alert to the risk of RSWS. Regular monitoring should be performed as hyponatremia can be asymptomatic until it is severe.

EPID-10. EPIDEMIOLOGY STUDY OF UNCOMMON CHILDHOOD BRAIN TUMOURS IN ASIAN CHILDREN

Our local registry identified 656 brain tumours from Jan 1999 to Dec 2018, (incidence: 29.8/yr/million). Other from Glioma, Medulloblastoma/PNET, Germ Cell tumours, Ependymoma, the remaining rarer tumours accounted for 18% (n=118). The 7 more common groups are: craniopharyngioma(n=28); ATRT(n=18); choroid plexus papilloma/CA(n=12); Ganglioglioma(n=11); ETMR(n=7); DNET(n=7); meningioma(n=6). Their respective incidences are 1.27; 0.81; 0.55; 0.5; 0.32; 0.32 0.27/yr/million. For craniopharyngioma, M:F=15:13 and median age was 7.4yrs (2mons-16.5yrs). 12/28 children had surgery alone and 13/28 had focal RT post-surgery with better outcome. 3 underwent intra-cystic interferon-beta also stable. For ATRT, M:F=7:8 and median age was 2.3yrs (4mos-14.2yrs). 2 had metastatic disease and 7/18 patients remained alive. For choroid plexus tumours, there were 7 papilloma, 2 atypia and 3 carcinoma. M:F=5:6 and median age was 1.5yrs (4mos-14yrs). All papilloma, 1/2 atypia and 1/3 carcinoma survived. For ganglioglioma, M:F=7:4 with median age of 5.5yrs (5mos-13.2yrs). They commonly presented with seizure and only one died (brainstem primary). The ETMR includes ependymoblastoma and medulloepithelioma, they had quite different clinical characteristics and outcome. 6/7 DNET had convulsion and M:F=6:1. Median age was 11.5yrs (2.66-14yrs). They all survived even if incompletely resected. For meningioma, 1/6 had germline mutation of NF-2 gene. M:F=3:3 and onset was >8yrs except the NF-2 patient. All survived but the NF-2 had multiple recurrences. 4 patients developed secondary meningioma due to irradiation but they were >18yrs so excluded. In summary, rarer forms of childhood brain tumours only accounted for <20% of all brain tumours and they had diverse presenting features and outcome.

HGG-48. ROS1 INHIBITOR ENTRECTINIB USE IN RELAPSE/REFRACTORY INFANTILE GLIOBLASTOMA WITH POSITIVE ROS1 FUSION - A CASE REPORT WITH PROMISING RESPONSE

INTRODUCTION

Infantile glioblastoma is rare with poor prognosis. Recent molecular study for infantile hemispheric high grade glioma found its association with ALK/ROS1/NTRK/MET pathway. This suggested the potential use of targeted therapy for refractory / relapse patients. CASE: A newborn presented with apnea, CT brain showed intracranial haemorrhage. MRI then showed a left parietal tumour with bleeding and mass effect. Craniotomy achieved subtotal resection. Chemotherapy VCR/CPM alternating with CDDP/VP-16 was given for one year. Patient was stable with static residual tumour during chemotherapy. However patient developed status epilepticus two weeks after off treatment. MRI showed significant tumour progression which required 2nd & 3rd debulking surgery. Molecular assay by nanostring panel showed BRAF-KIAA1549 fusion. MEK inhibitor Trametinib was tried for 3 months and stopped as disease progression. Further molecular assay by RNASeq showed presence of ROS1 fusion (ZCCHC8-ROS1) while absent of BRAF fusion. Patient underwent 4th debulking surgery as impending herniation while waiting for the targeted therapy. It was complicated with right hemiplegia and facial nerve palsy postoperatively. Finally, ROS1 inhibitor Entrectinib was started 2 weeks later. It was well tolerated without significant adverse reaction. Patient made dramatic neurological recovery including improved facial nerve palsy, able to walk unaided and self feed. MRI brain 1 and 3 months after Entrectinib showed interval reduction in residual tumour. Patient is currently progression-free for 6 months.

CONCLUSION

Early molecular study for infantile glioblastoma is useful to guide novel therapy. Molecular result may varies between different panels or change over time, to be interpreted with caution.

Timing of adjuvant radiotherapy and treatment outcome in childhood ependymoma

BACKGROUND

Several trials incorporating adjuvant focal RT for treatment of young children with ependymoma have demonstrated improved survival with acceptable adverse effects. The optimal timing of RT administration is, however, unknown.

PROCEDURE

A retrospective review of territory-wide database was performed to identify pediatric patients with ependymoma diagnosed between 1995 and 2011. OS and EFS were compared between patients receiving upfront RT (<150 days of diagnosis), delayed RT (≥150 days of diagnosis), or no RT.

RESULTS

Thirty-one patients with intracranial ependymoma were identified. Median age was 3.5 years and 14 (45%) were male. Primary tumor was supratentorial in 10 (32%) and infratentorial in 21 (68%). All patients underwent initial surgery, with gross-total resection (GTR) in 27 (87%). Twelve (39%) received upfront RT, 10 (32%) had delayed RT and 9 (29%) had no RT. During the study period, there were 11 relapses (35%) and 10 deaths (32%). Five-year OS was 69.9% and 5yr-EFS was 49.3%. In univariate analysis, GTR led to improved OS (P < 0.001) and EFS (P = 0.004); superior OS and EFS was observed in patients who received RT when compared with those without (P = 0.018 and 0.011, respectively). Upfront RT also resulted in better OS and EFS than delayed RT (P = 0.049 and 0.014, respectively). No significant effect on survival was observed with age, sex, tumor location, RT dosage, and protocol used. In multivariate analysis, GTR significantly improved OS (P = 0.002) and EFS (P = 0.004).

CONCLUSIONS

Our results support the early initiation of adjuvant RT in the multi-modal management of pediatric ependymomas.

One man, one disease?

We report the case of a 12-year-old girl with a strong family history of malignancy who presented with immature teratoma and gliomatosis peritonei. Despite first and second line chemotherapy, the disease ran an unusually refractory course. Although the presentation was not the typical tumour presentation of Li-Fraumeni syndrome (LFS), we proceeded to undertake tumour genetic testing of the patient and her parents. LFS was diagnosed in this patient and her father with a sequence variation of CGG>TGG, R248W, which is one of the most common transcriptionally inactive mutations detected in LFS. Genetic counselling was offered to the father. A tumour screening programme and genetic screening for the p53 gene mutation for the surviving family members can be offered once consent is obtained from the father. This case illustrates the importance of cancer genetic study, even if the tumour presentation is not typical for any familial cancer syndrome.

Clonal evolution of 8p11 stem cell syndrome in a 14-year-old Chinese boy: a review of literature of t(8;13) associated myeloproliferative diseases

We describe a case of coexisting BCR-ABL negative myeloproliferative disorder and precursor T-cell lymphoblastic lymphoma associated with t(8;13) involving FGFR1 at 8p11 in a 14-year-old boy who presented with generalized lymphadenopathy and an abdominal mass. JAK2 mutation and FIP1L1-PDGFRalpha were not detected. RT-PCR revealed the ZNF198-FGFR1 fusion transcript in both the bone marrow (BM) and lymph node (LN) of the patient at diagnosis. Of interest, reciprocal FGFR1-ZNF198 fusion transcript was demonstrated in the BM but not LN. Also differential clonal TcRgamma gene rearrangements in the BM and LN samples were observed. These findings provide novel insights into the genetic pathogenesis.

Improved outcome of acute lymphoblastic leukaemia treated by delayed intensification in Hong Kong children: HKALL97 study

OBJECTIVE

To study the outcome of children with acute lymphoblastic leukaemia who were treated using a protocol including one or two delayed intensifications.

DESIGN

Prospective single-arm multicentre study.

SETTING

Five designated children cancer units of the Hospital Authority of Hong Kong.

PATIENTS

Children aged between 1 and 17.9 years with newly diagnosed acute lymphoblastic leukaemia seen from November 1997 to December 2002.

INTERVENTION

Chemotherapy was modified from a German Berlin-Frankfurt-Muenster 95 (BFM95) protocol that included a delayed intensification similar to the induction phase repeated 5 months after diagnosis. High-risk patients were given double delayed intensification.

MAIN OUTCOME MEASURES

Overall survival and event-free survival of the whole group and the three risk groups (standard-, intermediate-, and high-risk groups), and comparison with historical controls.

RESULTS

A total of 171 patients were recruited with a median age at diagnosis of 5.57 years (range, 1.15-17.85 years). The induction remission rate was 95.3% and non-leukaemia mortality during remission was 2.3%. At 4 years, the relapse rate of this (HKALL97) study was significantly lower than that of the HKALL93 study (15.7 vs 37.3%; P<0.001). The 4-year overall survival of HKALL97 and HKALL93 studies were 86.5% and 81.8%, respectively (P=0.51). The 4-year event-free survival for HKALL97 and HKALL93 studies were 79% and 65%, respectively (P=0.007). Nonetheless the difference of event-free survival was most remarkable in the intermediate-risk group: 75.6% and 53.1% for HKALL97 and HKALL93 studies, respectively (P=0.06).

CONCLUSION

A more intensive delayed consolidation phase improved the outcome for children with acute lymphoblastic leukaemia by reducing relapses at 4 years. The early treatment complications were manageable and non-leukaemia mortality during remission remained low.

Bone mineral density in children with thalassaemia major: determining factors and effects of bone marrow transplantation

Osteoporosis and osteopenia affect up to half of patients with thalassaemia major (TM). We investigate the effects of acquired factors and BMT on bone mineral density (BMD) in these patients. In all, 53 patients on regular transfusion (BT group) and 33 patients at 5.7+/-1.9 years post transplant (BMT group) were recruited. BMD was measured by dual energy X-ray absorptiometry. Serum concentrations of osteocalcin, bone-specific alkaline phosphatase (ALP), beta-crossLap and urinary cross-linking deoxypyridinoline (DPD) were measured by chemiluminescence and enzyme immunoassay, respectively. Severe BMD deficit (Z-score <-2.5) at spine and hip were noted in 62 and 35% of BT group. Serum osteocalcin (beta=-0.463; P=0.006) was predictive of spine BMD, whereas age (beta=-0.843; P=0.007) and urine DPD (beta=-0.439; P=0.037) were associated with hip BMD in BT group. Among BMT patients, post transplant duration (beta=0.450; P=0.009) and serum bone-specific ALP (beta=-0.495; P=0.013) were associated with spine BMD. Severe BMD deficit was less common among BMT than BT patients (6 vs 35%; P=0.036). The mean (s.d.) osteocalcin levels in BMT and BT groups were 96.4 (72.7) microg and 68.9 (40.3) microg/l, respectively (P=0.037). In conclusion, severe BMD deficit is common in Chinese TM patients and BMT may reverse BMD deficit in these patients.

Oseltamivir prophylaxis during the influenza season in a paediatric cancer centre: prospective observational study

OBJECTIVE

To determine the role of oseltamivir prophylaxis for immunocompromised patients.

DESIGN

Prospective, non-blinded, non-controlled observational study.

SETTING

A paediatric cancer centre, Hong Kong.

PARTICIPANTS

Thirty-two patients, immunocompromised by chemotherapy or bone marrow transplantation during an influenza season in 2001.

INTERVENTION

Oral oseltamivir prophylaxis 75 mg/d for 8 weeks.

MAIN OUTCOME MEASURES

Laboratory-confirmed influenza infection, symptoms of influenza, drug compliance, and any side-effects from oseltamivir treatment. Laboratory monitoring included virological surveillance for influenza A and B, blood counts, and renal and liver function tests.

RESULTS

Patients' median age was 14.3 years (range, 6.3-23.4 years). Underlying conditions included malignancy (n=29) and other haematological diseases (n=3). No documented influenza infection according to serological tests was present throughout the study period. Five patients with symptoms of upper respiratory tract infection did not have any influenza infection detected by rapid virological assay and viral culture. For 16% of patients, the main side-effect in the study was gastro-intestinal upset.

CONCLUSIONS

Oral oseltamivir 75 mg once daily for 8 weeks may be useful in the prevention of influenza infection in patients immunocompromised by chemoradiotherapy; side-effects are few and acceptable.

Unrelated umbilical cord blood transplantation in children: experience of the Hong Kong Red Cross Blood Transfusion Service

OBJECTIVE

To review the outcome of unrelated umbilical cord blood transplantation in children using cord blood from the Hong Kong Red Cross Blood Transfusion Service.

DESIGN

Retrospective study.

PATIENTS

Records of eight patients who received unrelated umbilical cord blood transplants between 1999 and 2003 were reviewed.

MAIN OUTCOME MEASURES

Engraftment of haematopoietic cells and graft-versus-host disease after transplantation.

RESULTS

The median age of the patients was 4.9 years (range, 1.0-9.4 years). Five patients had acute leukaemia, one had non-Hodgkin's lymphoma, one had X-linked adrenoleukodystrophy, and one had mucolipidosis. The infused umbilical cord blood units contained a median of 6.7 x 10(7) /kg nucleated cells and 4.0 x 10(5) /kg CD34-positive cells. Neutrophil engraftment was achieved at a median of 13 days (range, 11-19 days) and, for seven patients, platelet engraftment was achieved at a median of 39 days (range, 24-98 days). Acute graft-versus-host disease occurred in all patients (grades I to III). One of the patients died because of encephalitis; of the other seven, five developed chronic graft-versus-host disease of the skin. At a median follow-up of 2 years, the four patients with leukaemia and the one with non-Hodgkin's lymphoma remained in continuous complete remission; the patient with adrenoleukodystrophy showed stabilisation of neurological condition.

CONCLUSION

The Hong Kong Red Cross Blood Transfusion Service Cord Blood Bank stored cord blood units of good quality for transplantation, the outcome of which was comparable to that of bone marrow transplantation.

Treatment of acute lymphoblastic leukemia in Hong Kong children: HKALL 93 study

A population-based multicentre study for childhood acute lymphoblastic leukemia (ALL) was conducted in Hong Kong from 1993 to 1997. One hundred and forty-five newly diagnosed ALL patients were treated by the HKALL 93 protocol. Patients were stratified into three risk groups according to age, presenting white cell count, immunophenotyping and cytogenetic study. The patients received the same induction and early and late intensification at week 5 and week 20. Fifty-eight standard risk (SR) patients received regular intrathecal methotrexate as CNS preventive therapy, while 49 intermediate risk (IR) patients received high dose intravenous methotrexate and regular intrathecal methotrexate. Thirty-eight high risk (HR) patients were treated with prophylactic cranial irradiation and an additional intensification block at week 35. The induction remission rate was 97.2% with 2% induction death. Two patients died during first complete remission. Relapse occurred in 20.7, 42.9 and 42.1% of SR, IR and HR patients respectively. By multivariate logistic regression, age> or =10 years and white cell count> or =100 x 10(9)/l were the two significant variables accounting for mortality. The 5-year overall and event-free survival of the whole group was 81.3 and 62.6% respectively. According to risk groups, the event-free survival was 79, 49 and 61% for SR, IR and HR patients respectively, while the overall survival was 96, 73 and 68% for SR, IR and HR patients respectively. In conclusion, the treatment protocol had low treatment-related mortality but was associated with a rather high relapse rate, especially in IR patients. Salvage therapy achieved sustained second remission in some patients. More intensive treatment especially a late intensification is required to improve the outcome.

Morbidity and mortality patterns of thalassaemia major patients in Hong Kong: retrospective study

OBJECTIVES

To study the morbidity and mortality patterns of transfusion-dependent thalassaemia major patients in Hong Kong, and compare the outcomes of these patients according to different periods of birth.

DESIGN

Retrospective study.

SETTING

Paediatric departments of three regional hospitals, Hong Kong.

SUBJECTS AND METHODS

Medical records of thalassaemia major patients were reviewed. Data gathered included demographic and survival data, complications of iron overload, repeated transfusion, and bone marrow transplantation; the probability of survival of three cohorts was also estimated.

RESULTS

Two hundred and thirty-two patients were studied at a median age of 15.5 years (range, 1.4-30.3 years). There were 60 patients born before 1980 (cohort 1), 117 patients born between 1980 and 1989 (cohort 2), and 55 patients born after 1989 (cohort 3). The median age of starting desferrioxamine was 8 years, 4 years, and 3 years for cohorts 1, 2, and 3, respectively. Cardiomyopathy, diabetes mellitus, and hypothyroidism occurred in 15.1%, 8.6%, and 6.9% of patients with thalassaemia major, respectively. The above complications developed in 5% to 12% of cohort 2 patients. Delayed puberty was present in 38.4% and hormonal replacement for gonadal failure was required in 29.7% of evaluable patients. Short stature was common and the median height standard deviation score was -1.63. Twenty patients had died, and cardiomyopathy was the leading cause of death, followed by complications of bone marrow transplantation. The probability of survival beyond the age of 20 years was 87.6%.

CONCLUSION

Despite the use of iron chelation in the past two decades, severe complications of iron overload still occurred even in those who started chelation therapy early. Cardiomyopathy was the leading cause of death, while endocrinopathies and short stature were common complications especially in teenagers and adults.

Human herpesvirus-6 encephalitis after unrelated umbilical cord blood transplant in children

Three children developed human herpesvirus-6 (HHV-6), variant B encephalitis after unrelated umbilical cord blood transplant, in a single center. They developed clinical manifestations of encephalitis around day 17 post transplant. Impairment of consciousness, incoherent speech, episodic focal pruritus, motor weakness, convulsions and severe hyponatremia were features at presentation. Radiological investigation of brain ranged from unremarkable to extensive white matter and meningeal lesions. Diagnosis was established by the presence of HHV-6 DNA in cerebrospinal fluid (CSF). Retrospective analyses of plasma revealed the presence of viral DNAemia prior to the onset of disease in two subjects. Treatment with ganciclovir or foscarnet was given. Two subjects did not achieve engraftment and died of other transplant-related complications on day 38 and 56 post-transplant, respectively. One subject achieved disease-free survival for more than 1 year with a satisfactory neurological outcome. In conclusion, HHV-6 encephalitis is not uncommon among patients undergoing umbilical cord blood transplantation. It is worth conducting further studies on early diagnosis and optimal management of this potentially fatal disease.

Liver disease in transfusion dependent thalassaemia major

AIMS

To study the prevalence and severity of liver diseases of transfusion dependent thalassaemia major patients, and correlate the histological and biochemical changes of iron overload in liver with the peripheral blood markers.

METHOD

Liver biopsy was performed to assess the histological changes and liver iron content (LIC).

RESULTS

One hundred patients were evaluated (median age 11.7 years, range 1.5-27). A total of 81 liver biopsies were performed in 73 patients; 43 samples were analysed for LIC. Grade 3-4 haemosiderosis and hepatic fibrosis was found in 44% and 30% of patients respectively; both were significantly associated with higher serum ferritin, liver enzymes, and LIC. Very high LIC (>15 mg/g dry weight) was present in 16.3% of patients.

CONCLUSION

Severe haemosiderosis and hepatic fibrosis were common in patients with thalassaemia major despite the use of chelation therapy. Liver biopsy provided information on fibrosis and LIC which could not be accurately predicted from peripheral blood markers.

Haematopoietic stem cell transplantation for thalassaemia major in Hong Kong: prognostic factors and outcome

From August 1992 to August 1999, 44 patients received allogeneic haematopoietic stem cell transplantation in a single institution. The donors were HLA-identical siblings except for one who was a phenotypically matched father. Thirty-eight patients received bone marrow stem cells and the others received peripheral blood stem cells or umbilical cord blood (UCB). The mean age at transplant was 10.7+/-5.1 years, ranging from 1.8 to 21 years. Patients received busulphan (16 mg/kg) and cyclophosphamide (150 to 200 mg/kg) as conditioning, and antithymocyte globulin was given to 42 patients to prevent graft rejection. All had engraftment except a patient who received a UCB transplant. Four patients died from early treatment-related mortality, and one died from interstitial pneumonitis 3 months after transplant. Two patients developed secondary graft rejection and both received a second transplant. Thirty-eight patients survived and all except one were transfusion independent. The 5-year overall and event-free survival rates were 86% and 82%, respectively. By multivariate stepwise Cox proportional hazard analyses, severe veno-occlusive disease (VOD) of liver and Pesaro class 3 features were the significant factors associated with survival. Patients aged more than 11 years were more inclined to develop VOD. In conclusion, haematopoietic stem cell transplantation should be performed early if an HLA identical sibling is available.