927. Clinical Characteristics and Outcomes of Norovirus Infection in Patients with Hematologic Malignancies: A Retrospective, Single Center Study

Background Norovirus (NV) gastroenteritis has been identified as a cause of significant morbidity among hematopoietic stem cell transplant (HSCT) recipients, often with associated complications. Current guidelines recommend symptomatic relief with antimotility agents, rehydration, and reduction in immune suppression. Nitazoxanide (NTZ) is an anti-parasitic agent but some literature suggests a benefit of nitazoxanide therapy for NV. Methods We conducted a single center, retrospective chart review study and evaluated adult patients (age >18 years) who had NV infection and either: 1) underwent stem cell transplantation; or 2) received myeloablative chemotherapy within 4 weeks of NV diagnosis by positive test on gastrointestinal pathogen panel during the time period from January 2015 through March 2020. Results 26 patients were reviewed. 14 patients (54%) had a history of HCST prior to infection. Three patients (12%) received both myeloablative chemotherapy and HSCT within four weeks of NV infection. Six patients (46%) had autologous, six (46%) had matched unrelated donor, and one (8%) had haploidentical allogeneic transplants. Nine (69%), three (23%), and one (8%) underwent myeloablative, reduced intensity and non-myeloablative conditioning, respectively. Median duration of diarrhea was 4.5 days (IQR = 2.25-7 days). Three (12%) patients received NTZ or intravenous immune globulin. The 6 month mortality was 42% (11/26), however, none of the deaths were directly attributable to NV infection. Conclusion NV infection led to severe diarrheal disease in our cohort. Overall mortality was high, and a trend toward increased mortality was seen among patients receiving NV-directed therapy; these patients likely received NV-directed therapy due to the severity of their illness. Clinicians must have a high suspicion for this illness and obtain PCR testing for timely diagnosis and management. Table 1. Characteristics of patients with hematologic malignancies and norovirus infection Disclosures All Authors: No reported disclosures

Early Endothelial Activation in a Mouse Model of Graft vs Host Disease Following Chemotherapy

Allogenic hematopoietic stem cell transplant (allo-HSCT) can lead to sinusoidal obstruction syndrome (SOS) and graft-versus-host disease (GvHD) in some individuals. GvHD is characterised by an immune triggered response that arises due to donor T cells recognizing the recipient tissue as “foreign”. SOS results in impaired liver function due to microvascular thrombosis and consequent obstruction of liver sinusoids. Endothelial damage occurs following chemotherapy and allo-HSCT and is strongly associated with GvHD onset as well as hepatic SOS. Animal models of GvHD are rarely clinically relevant, and endothelial dysfunction remains uncharacterised. Here we established and characterised a clinically relevant model of GvHD wherein Balb/C mice were subjected to myeloablative chemotherapy followed by transplantation of bone marrow (BM) cells± splenic T-cells from C57Bl6 mice, resulting in a mismatch of major histocompatibility complexes (MHC). Onset of disease indicated by weight loss and apoptosis in the liver and intestine was discovered at day 6 post-transplant in mice receiving BM+T-cells, with established GvHD detectable by histology of the liver within 3 weeks. Together with significant increases in pro-inflammatory cytokine gene expression in the liver and intestine, histopathological signs of GvHD and a significant increase in CD4+ and CD8+ effector and memory T-cells were seen. Endothelial activation including upregulation of vascular cell adhesion molecule (VCAM)- 1 and downregulation of endothelial nitric oxide synthase (eNOS) as well as thrombosis in the liver indicated concomitant hepatic SOS. Our findings confirm that endothelial activation is an early sign of acute GvHD and SOS in a clinically relevant mouse model of GvHD based on myeloablative chemotherapy. Preventing endothelial activation may be a viable therapeutic strategy to prevent GvHD.

Myeloablative versus non-myeloablative consolidative chemotherapy for newly diagnosed primary central nervous system lymphoma: Results of CALGB 51101 (Alliance).

7506 Background: Optimal consolidative therapy for primary central nervous system lymphoma (PCNSL) is not defined. Avoidance of whole brain radiation may reduce risk of neurotoxicity. Non-radiation consolidative options include myeloablative chemotherapy with autologous stem cell transplantation (HDT/ASCT) or non-myeloablative chemotherapy. Methods: This is a randomized phase 2, National Clinical Trials Network study of induction methotrexate (MTX) (8 g/m2 days 1, 15), temozolomide (TMZ) (150-200 mg/m2 D7-11), and rituximab (RTX) (C1 D3, 10, 17, 24 and C2 D3, 10 ) in four 28-day cycles followed by one cycle of cytarabine (ARA-C) (2 g/m2 BID, D1, 2) (MTRA). After induction, patients (pts) received consolidation with thiotepa (5 mg/kg BID, D -5, -4) plus carmustine (400 mg/m2, day -6) and ASCT (Arm A) or one cycle of ARA-C (2 g/m2 BID, D1-4) plus infusional etoposide (40 mg/kg over 96h) (Arm B). Pts were stratified on age and performance status and randomized 1:1 before induction. The primary endpoint was progression-free survival (PFS) from randomization. With 110 pts, there was 84% power to detect an improvement in PFS using a log-rank test (1-sided α= 10%), assuming a median PFS of 3 months for pts who progress during induction, and a median PFS of 2 years (yrs) for Arm B and 4.5 yrs for Arm A consolidation. This report includes the results for the primary endpoint analysis. Results: 113 pts (median age 61 yrs, range 33-75) were randomized (Arm A: 57, Arm B: 56) across 27 centers. 108 eligible pts who received induction therapy were included in the primary endpoint analysis (Arm A: 54, Arm B: 54). 72/108 pts started consolidation and 70/72 completed consolidation per protocol (Arm A: 36, Arm B: 34). With a median follow-up of 3.8 years, median PFS from randomization was 6 yrs (95% CI 3.9-not reached) in Arm A vs 2.4 yrs (95% CI 0.6-not reached) in Arm B (p = 0.02). However, more pts randomized to Arm B went off treatment before consolidation due to progression or death (28% vs 11%, p = 0.05). PFS landmarked at start of consolidation demonstrated a trend for improved PFS favoring Arm A (HR 0.58, 95% CI 0.25-1.36; p = 0.21). Median OS was not reached in either arm, and 3-yr estimates were 83% (95% CI 69-91; Arm A) vs 72% (95% CI 57-82; Arm B). Toxicities were similar between arms with no treatment-related mortality during consolidation. Conclusions: MTRA induction followed by myeloablative consolidation (Arm A) had improved PFS vs MTRA induction followed by non-myeloablative consolidation (Arm B), though more progressions or deaths leading to treatment discontinuation prior to consolidation in Arm B were noted. Both consolidation regimens were well-tolerated with encouraging PFS and OS in newly-diagnosed PCNSL. Support: U10CA180821, U10CA180882; https://acknowledgments.alliancefound.org . Clinical trial information: NCT01511562.

Treating pediatric metastatic neuroblastoma with chemotherapy-based multimodality approach in a non-transplant setting - experience from a developing country

Background: Children with metastatic neuroblastoma have inferior survival despite therapeutic advances. Myeloablative chemotherapy followed by stem cell transplantation, accepted as the current standard of care, is not accessible to patients in many developing countries due to resource constraints. We share our experience of treating metastatic neuroblastoma in a non-transplant facility with conventional chemotherapy, surgery, and radiotherapy. Method - Retrospective study of children 1-14years of age treated for metastatic neuroblastoma in our center from January 2008 to December 2017 Results – Eighty-nine patients with metastatic neuroblastoma received treatment. Mean age was 3.5years and male:female ratio was 1.1:1. The commonest primary site was suprarenal(55%) and commonest site of metastasis was bone marrow(76%). 40% patients had multiple metastatic sites. Mean baseline LDH was 3724 U/L(range303-16609 U/L) and most(65%) patients had LDH>750U/L.53 patients(59.6%)had good response to chemotherapy as evidenced by clearance of metastatic disease, but out of them, 43 patients (81%) progressed subsequently. 26 patients underwent surgery and 12 patients received maintenance therapy. 74 patients(86%) developed recurrence and all but one died. Median time to recurrence and death were 9months(range 0-120months) and 10months(range 1-123months) respectively. At a median follow-up of 72months(range15-135months), 16 patients are alive, with 5-year disease-free survival and overall survival of 17.6% and 18.4% respectively. Age, baseline LDH, chemotherapy regimen and response to treatment affected survival. Conclusion: Outcome of non-infant metastatic neuroblastoma remains dismal in a non-transplant setting. Younger age, lower baseline LDH and good response to chemotherapy appear to confer survival advantage, and may be used for risk-stratification in developing countries.

Myeloablative chemotherapy in testicular cancer patient

Chemotherapy is the standard treatment for metastatic testicular cancers. The autologous hematopoietic stem cell transplantation is a salvage option for relapsed patients. The paper presents a case of a 20-year-old patient with stage IIIC non-seminoma treated with BEP chemotherapy and autologous transplantation of stem cells, which allowed to achieve durable remission.

Autologous Stem Cell Transplantation for Myeloma: Cytoreduction or an Immunotherapy?

The incidence of multiple myeloma (MM), a bone marrow (BM) resident hematological malignancy, is increasing globally. The disease has substantial morbidity and mortality and remains largely incurable. Clinical studies show that autologous stem cell transplantation (ASCT) remains efficacious in eligible patients, providing a progression free survival (PFS) benefit beyond novel therapies alone. Conventionally, improved PFS after ASCT is attributed to cytoreduction from myeloablative chemotherapy. However, ASCT results in immune effects beyond cytoreduction, including inflammation, lymphodepletion, T cell priming via immunogenic cell death, and disruption of the tumor BM microenvironment. In fact, a small subset of patients achieve very long-term control of disease post-ASCT, akin to that seen in the context of immune-mediated graft-vs.-myeloma effects after allogeneic SCT. These clinical observations coupled with recent definitive studies in mice demonstrating that progression after ASCT represents immune escape as a consequence of T cell exhaustion, highlight the potential for new immunotherapy maintenance strategies to prevent myeloma progression following consolidation with ASCT.

IMMU-08. reMATCH PROTOCOL: PHASE II STUDY OF EX-VIVO EXPANDED AUTOLOGOUS TUMOR SPECIFIC LYMPHOCYTE TRANSFER (X-ALT) + TOTAL TUMOR RNA DC VACCINE (TT-RNA DC) DURING RECOVERY FROM MYELOABLATIVE CHEMOTHERAPY (MAC) AND PERIPHERAL BLOOD STEM CELL (PBSC) RESCUE OR NON-MYELOABLATIVE CHEMOTHERAPY (NMAC) AND PBSC IN PATIENTS (PTS) WITH RECURRENT PNET (R-PNET)

A phase II study was performed to assess vaccine-related toxicities and efficacy of x-ALT+tt-RNA DC following MAC +PBSC (group A) or NMAC +PBSC (group B) in pts with r-PNET. METHODS: Eligible pts underwent biopsy to confirm r-PNET and obtain tumor for vaccine preparation. Pts with local (group A) or metastatic (group B) disease received cytoreductive induction chemotherapy prior to either MAC (carboplatin+ thiotepa+ etoposide) or NMAC (cyclophosphamide + fludarabine) respectively and then received one dose of x-ALT (3 x 107cells/kg), PBSC, and 3 doses of bi-weekly intradermal tt-RNA DCs (107cells each). Patients were followed for survival and vaccine-related toxicities. Correlative studies included TCR RNA sequencing and measurement of serum cytokines. RESULTS: 20 evaluable pts (75% males) [Medulloblastoma 17, PNET 3; unifocal 40%] were treated on protocol (group A 7, group B 13). There were no significant vaccine-related toxicities. At a median follow-up of 8.5 months, 5 patients (all with medulloblastoma) are alive following vaccine therapy; 2 pts with SD (3.5+ and 6.5+ months) and 3 pts with PD that stabilized with salvage therapies (26+, 31+, and 46+ months respectively). One patient with medulloblastoma and bone marrow involvement who had PD despite MAC, had an almost complete response one month following x-ALT + tt-RNA DCs and TCR RNA sequencing demonstrated massive clonal expansion of T cells. Correlative studies are ongoing. CONCLUSIONS: x-ALT+tt-RNA DC following either MAC or NMAC is safe and shows signs of biologic and possible clinical activity in some pts with r-PNET.

MBCL-13. CORRELATION OF HISTOPATHOLOGY, CHROMOSOMAL MICROARRAY, AND NANOSTRING BASED 22-GENE ASSAY FOR MEDULLOBLASTOMA SUBGROUP ASSIGNMENT ON “HEAD START” 4 CLINICAL TRIAL

“Head Start” 4 (HS 4) is a prospective randomized clinical trial that tailors treatment based on medulloblastoma molecular subgroups and response to induction chemotherapy to compare efficacy of one versus three (tandem) cycles of myeloablative chemotherapy. Advances in RNA and DNA profiling have identified four molecular subgroups of medulloblastoma with prognostic significance: Sonic Hedgehog (SHH) subtype, WNT subtype, Group 3, and Group 4. In HS 4 trial, we utilize a combination of histopathology and immunohistochemistry (pathology/IHC), as well as chromosomal microarray analysis (CMA) utilizing OncoScanTM (Thermo Fisher) to classify medulloblastoma samples into either SHH, WNT, or non-WNT/non-SHH (Group 3/4) subgroups at the time of diagnosis. NanoString based 22-gene assay is performed retrospectively to test concordance. We have pathology/IHC, CMA, and NanoString data on 26 infants and young children with medulloblastoma enrolled on HS 4. Pathology/IHC was able to assign samples to SHH, WNT, and non-WNT/non-SHH subgroups in all but two cases: one case was classified as Group 3, and the second as SHH by both CMA and NanoString. CMA was indeterminate in six cases, of which, pathology/IHC was able to assign all six samples aforementioned three subgroups. NanoString was indeterminate in two cases: one case was classified as SHH by CMA and pathology/IHC, and the second case was indeterminate by CMA but was assigned as non-WNT/non-SHH on pathology/IHC. There is excellent correlation between NanoString and combination of histopathology and CMA for core medulloblastoma subgrouping on HS 4. Methylation studies are ongoing.