Citations

Abstract BACKGROUND: Multiple Myeloma (MM) is an incurable disease with no known germline high penetrant risk gene. The higher risk of MM among affected relatives suggests a genetic contribution to the etiology. To date, 24 common risk variants with low effect sizes were identified using genome-wide association studies, which account for 17% of heritability. However, a systematic analysis of the known rare alleles in cancer predisposition genes has not been undertaken so far in MM. We collaborated with six other academic centers across the United States to identify and select cases for analysis of germline predisposition of MM. METHODS: We performed whole exome, next-generation sequencing of 2,387 familial or early onset germline MM cases from the myeloma sequencing consortium (MMSEQ). We called 1.5 million variants and performed standard quality control of the data. We also obtained exome data on 1,285 cases from UK Biobank (UKBB) and 344,513 non-cancer controls (total=3,672 cases). We analyzed the ultra-rare, coding variants in 90 clinically relevant or putative candidates for cancer predisposition. We then used the automated variant curator PathoMAN to annotate and assert pathogenicity of each variant. We contrasted our results with assertions of pathogenicity from ClinVar and tested for gene association with MM. RESULTS: Overall, we observed several pathogenic or likely pathogenic variants, both singleton and recurrent founder mutations. In the MMSEQ, 8.7% of MM cases harbored a pathogenic variant in these known/putative cancer predisposition genes. Predominant group of pathogenic variants were observed within CHEK2 (19%), TP53 (8%), and ATM (5%). A case-control analysis revealed strong association with TP53 and weakly with ATM. In the familial/early onset MMSEQ cases, TP53 mutations were enriched 68 times more than in the UKBB controls. Our preliminary results suggest that known genes of cancer susceptibility such as TP53 and ATM may also play a role in myeloma risk. CONCLUSION: In a large study of multi-center MM cases, we identified a significant proportion of individuals who are carriers of known (solid) cancer predisposition genes. This study suggests that these known cancer predisposition genes may be relevant in a subset of MM cases. Citation Format: Michael T. Conry, Nicola Camp, Celine Vachon, Michelle Hildebrandt, Elizabeth E. Brown, Steven M. Lipkin, Judy Garber, Susan L. Slager, Samantha Stokes, Aaron D. Norman, Aalin Izhar, Sita Dandiker, Kylee Maclachlan, Kenneth Offit, Saad Usmani, Vijai Joseph. Pathogenic germline mutations and risk of multiple myeloma. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5229.

Abstract Cellular heterogeneity within glioblastoma multiforme (GBM) is a key driver of resistance to standard-of-care therapeutic approaches such as DNA damage (temozolomide, TMZ), angiogenesis inhibition (Bevacizumab, BM), radiation necrosis, and surgical resection. As such, understanding and targeting heterogeneous tumor-associated populations is a critical aim of ongoing GBM research. Central nervous system (CNS) resident microglia constitute significant percentages of primary GBM samples, often up to 50% of bulk tumor. Additionally, glioblastoma-associated microglia have been implicated in intra-tumoral immunosuppression, and are thus a key barrier to successful implementation of immunotherapies that seek to enhance T-cell mediated anti-tumoral cytotoxicity. As such, insight into targetable pathways that upregulate immunosuppressive cytokines within GBM-associated microglia is necessary for overcoming immuno-therapeutic failure. Here, we identify expression of the cytokine TWEAK (TNFSF12) and its receptor Fn14 (TNFRSF12A) within the myeloid compartment of primary GBM samples via scRNA-seq. Furthermore, we demonstrate TWEAK-mediated reprogramming of GBM-associated microglia towards an immunosuppressive phenotype capable of inhibiting CD8+ T cell activation and proliferation. These findings unveil a potent, targetable axis of immunosuppression within GBM and are thus an exciting step towards enhancing efficacy of existing T-cell based anti-cancer strategies for GBM patients. Citation Format: Angad Beniwal, Ryan Eghlimi, Kenneth D. Alexander, Mylan R. Blomquist, Nhan Tran. Role of TWEAK-Fn14 axis in driving immunosuppression in glioblastoma multiforme [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6442.

No standard treatment paradigm exists for previously irradiated locally recurrent rectal cancer (PILRRC). Carbon-ion radiotherapy (CIRT) may improve oncologic outcomes and reduce toxicity compared with combined modality therapy (CMT). Eighty-five patients treated at Institution A with CIRT alone (70.4 Gy/16 fx) and eighty-six at Institution B with CMT (30 Gy/15 fx chemoradiation, resection, intraoperative electron radiotherapy (IOERT)) between 2006 and 2019 were retrospectively compared. Overall survival (OS), pelvic re-recurrence (PR), distant metastasis (DM), or any disease progression (DP) were analyzed with the Kaplan–Meier model, with outcomes compared using the Cox proportional hazards model. Acute and late toxicities were compared, as was the 2-year cost. The median time to follow-up or death was 6.5 years. Median OS in the CIRT and CMT cohorts were 4.5 and 2.6 years, respectively (p ≤ 0.01). No difference was seen in the cumulative incidence of PR (p = 0.17), DM (p = 0.39), or DP (p = 0.19). Lower acute grade ≥ 2 skin and GI/GU toxicity and lower late grade ≥ 2 GU toxicities were associated with CIRT. Higher 2-year cumulative costs were associated with CMT. Oncologic outcomes were similar for patients treated with CIRT or CMT, although patient morbidity and cost were lower with CIRT, and CIRT was associated with longer OS. Prospective comparative studies are needed.

10585 Background: The 21-gene recurrence score assay (Oncotype DX, Genomic Health Inc., CA) is prognostic, quantifies predicted benefit of adjuvant chemotherapy, and informs clinical decisions for patients with early-stage, hormone receptor-positive (HR+) breast cancer (BC). Differences in Oncotype recurrence scores (RS) in individuals with and without BRCA1 and BRCA2 pathogenic variants (PV) have been demonstrated, but the results of this assay in patients with BC and germline CHEK2 or ATM PV have not previously been described. This is of particular relevance as CHEK2 BC have been associated with a worse prognosis. Methods: Prospective Registry of MultiPlex Testing (PROMPT) is an online research registry for individuals who have had multigene panel testing for inherited cancer susceptibility. We retrospectively evaluated Oncotype DX recurrence scores from PROMPT participants (pts) with PV or likely PV in CHEK2 or ATM. Mood’s median tests were used to compare median RS, and Yates corrected Chi-square tests were used to compare RS distributions between carriers and a genetically unselected reference population. Results: Oncotype DX reports were reviewed for 75 pts with 77 BC (n = 50 pts with CHEK2 PV with 51 BC; n = 24 with ATM PV; n = 1 with CHEK2 and ATM PV with 2 BC). Among CHEK2 carriers, median RS was 17 (range 2-43) overall, 17 (2-36) for pts < age 50, and 18.5 (8-43) for pts ≥age 50 (p-value 0.47), with distributions not significantly different than reference ( < 50, p = 0.70; ≥50, p = 0.93). Ten pts had low penetrance CHEK2 alleles (p.S428F or p.I157T) with median RS 16 (9-28) compared to 18 (2-43) in those with other CHEK2 alleles (p = 0.35). Among ATM carriers, median RS was 17 (1-35) overall, 17 (1-35) for pts < age 50, and 16 (11-32) for pts ≥age 50 (p = 0.51), with distributions also not significantly different ( < 50, p = 0.78; ≥50, p = 0.79). Conclusions: Unlike data seen in BC associated with BRCA1 and BRCA2, Oncotype DX RS in individuals with CHEK2 and ATM-associated BC are similar to the published genetically unselected commercial database median RS of 16, with no clear difference based on penetrance of CHEK2 allele. Proportions of patients < 50 and ≥50 with CHEK2 and ATM PV with RS within the range for chemoendocrine therapy consideration are also similar to the historical reference. The inferior prognosis that has been suggested in CHEK2 BC is not reflected in Oncotype DX RS. [Table: see text]

e20646 Background: Thymic carcinomas tend to be aggressive malignancies with variable patterns of immunostaining. We aimed to assess whether the outcome of patients with thymic carcinomas was associated with immunoreactivity for conventional and emerging immunohistochemical markers of thymic carcinoma versus thymoma. Methods: Scoring of CD5, CD117, EZH2, POU2F3, BAP1, and MTAP immunohistochemistry on whole slide sections was compared to overall survival (OS) and progression free survival (PFS) for 36 thymic carcinoma patients, 28 of whom had complete tumor resection and 8 of whom had incomplete tumor resection. Results: Positive CD5 staining (defined as staining in ≥50% of tumor cells) was present in 13/36 cases (36%) and was significantly associated with longer OS (P = 0.005, hazard ratio = 0.18, CI 0.03-0.63) but not PFS (P = 0.14, hazard ratio = 0.48, CI 0.16-1.26), whereas the other markers were not significantly associated with OS or PFS. Positive CD5 staining remained significantly associated with OS in squamous cell carcinoma subgroup analysis (n = 23, HR = 0.17, CI 0.03-0.65, P = 0.009), patients who did not receive neo-adjuvant treatment (n = 24, HR = 0.21, CI 0.03-0.85, P = 0.03) and after adjusting for incomplete resection (HR = 0.20, CI0.03-0.73, P = 0.01), M1 stage (HR = 0.19, CI 0.03-0.71, P = 0.01) or neoadjuvant treatment (HR = 0.19, CI 0.03-0.71, P = 0.01) in bivariate models. Positive CD5 staining was also significantly associated with age ≥60 years, absence of neoadjuvant treatment, and positive POU2F3 staining. Conclusions: CD5 staining in ≥50% of tumor cells was significantly associated with longer OS for thymic carcinoma patients. Our study supports the notion that CD5 immunohistochemistry may have utility as a prognostic marker for thymic carcinomas.

2529 Background: Tumor expression of the antiphagocytic protein CD47 (integrin associated protein) may lead to immunotherapy resistance (IO-R). PF-07257876 is a novel, IgG1, Fc-active, bispecific antibody targeting CD47 and PD-L1 designed to reverse IO-R, decrease anemia risk, and eliminate a priming dose. We report a Phase 1 dose escalation study (NCT04881045) in patients (pts) with advanced solid tumors, both IO-refractory and IO-naïve. Methods: The study enrolled pts ≥18 yrs with advanced non–small-cell lung carcinoma (NSCLC) and squamous cell carcinoma of the head and neck (SCCHN) with PD-L1 expression >1% post anti-PD-1/PD-L1 therapy. Pts with other PD-L1+ tumors known to express CD47 were included (prior IO not required). Pts received PF-07257876 at escalating dose levels in 28-day cycles. Primary objectives were safety (dose-limiting toxicity [DLT] rate), tolerability, and determination of Recommended Phase 2 Dose (RP2D). Secondary and exploratory objectives included pharmacokinetics (PK), blood receptor occupancy (RO), CD47 levels by immunohistochemistry (IHC), tissue biopsy findings, and objective response rate (ORR) per RECIST v.1.1. Results: As of 20OCT2022, 18 pts were enrolled (NSCLC: n = 6; SCCHN: n = 4; other: n = 8). Median (range) age 68 (46–79) yrs. PF-07257876 was given at ascending doses, 150-2400 mg by subcutaneous (SC) injection or SC infusion every 2 weeks. 16 (89%) pts had treatment-related adverse events (TRAEs): Grades 1/2: n = 12 (67%); Grade 3: n = 1 (6%); Grade 4: n = 3 (17%); no Grade 5. Most common TRAEs: injection site reaction/erythema (n = 13, 72%), thrombocytopenia (n = 6, 33%), anemia (n = 5, 28%), and nausea (n = 4, 22%). DLTs occurred in 2 of 3 pts at the highest tested dose (Grade 4 neutropenia and thrombocytopenia, n = 1; Grade 4 thrombocytopenia, n = 1; both pts recovered). One pt with IO-R SCCHN had a confirmed partial response (duration of response 16 wks). ORR was 5.6% (1/18). Drug exposure increase after 1st dose was not dose proportional. Blood RO was > 95% for PD-L1 and > 70% for CD47 with drug exposure. All pts’ baseline CD47 IHC levels were moderate to high. Pharmacodynamics cytokine profiling showed notable dose-response increases of IFNg, TNFa, CXCL9/10, CCL3/4, without IL-6 increase. Conclusions: PF-07257876 was well tolerated with manageable toxicity. Incidence and grade of anemia or thrombocytopenia were manageable. Target engagement of CD47 and PD-L1 in peripheral blood was high. Innate and adaptive cytokine modulation was observed. Antitumor activity was modest. Expansion is ongoing at 1800 mg. Clinical trial information: NCT04881045 .

7006 Background: Older adult patients (pts) with Philadelphia-chromosome-negative (Ph-) acute lymphoblastic leukemia (ALL) have poor survival with chemotherapy. The α-CD22 Ab-drug conjugate inotuzumab ozogamicin (InO) and α-CD19/CD3 T-cell engager blinatumomab (blina) were each superior to chemotherapy in Phase III studies in relapsed/refractory B-ALL. Because InO induces high CR rates and blina can induce durable remissions in low burden disease, we conducted a Phase II trial of induction InO then blina for older adults with newly-diagnosed (ND), Ph-, B-ALL. Methods: Eligible were pts ≥60 years old with ND, Ph-, CD22+ (≥20% of blasts) B-ALL without plan for allogeneic HCT (alloHCT). Pts with CNS leukemia or liver disease were excluded. Induction IA was InO 0.8 mg/m 2 day (d) 1, 0.5 mg/m 2 d8, d15 IV on a 21d cycle. Pts with adequate cytoreduction (marrow blasts by ≥50% or cellularity ≤20%) after IA went to IB if in CR/CRi (InO 0.5 mg/m 2 d1, d8, d15 IV; 28d cycle) or IC if no CR/CRi (InO 0.8 mg/m 2 on d1 and 0.5 mg/m 2 on d8 and d15 IV; 28d cycle). Those without cytoreduction to IA started course II blina. Pts without events in IA/B/C received course II blina CIV (9 mcg/d x 7d then 28 mcg/d x 21d; 14d break; 28 mcg/d x28d). Pts with CR/CRi to InO received 2 more 28d cycles of blina, others received 3 more. CNS prophylaxis was methotrexate 15 mg intrathecal x 8. The primary endpoint was 1-yr event-free survival (EFS) with a lower limit of a 90% CI for 1-yr EFS >10% defined as success. EFS was the time from therapy start to failure to achieve CR/CRh/CRi by end Course II, progression, relapse, or death, whichever occurred first. Results: Thirty-three eligible pts were treated (1 ineligible, 2 nd malignancy). The median age was 71 years (range 60-84). Median WBC count was 3,200/mcl (range 6-38,000). Median CD22 expression was 92% (range 21-100%). Eight pts had therapy-related ALL. The cumulative CR rates through Course IA/B/C and Course II were 85% and 97%, respectively (Table). With median follow up of 22 mo, the 1-yr EFS was 75% (95% CI 61-92%). The 2-sided 90% CI was 63-89% for 1-yr EFS with lower bound above 10% indicating regimen success. Twelve pts had events: 9 relapses, 2 deaths in remission (1 after alloHCT), and 1 death without remission from respiratory failure with sinusoidal occlusion syndrome of liver. The 1-yr OS was 84% (95% CI 72-98%). Nine pts have died, 6 after relapse. Conclusions: InO induction then blina consolidation is highly active for ND, Ph-, CD22+ B-ALL. The regimen is an option for older adults and a comparator regimen for future studies. Support: U10CA180821, U10CA180882, U10CA180820 https://acknowledgments.alliancefound.org . Clinical trial information: NCT03739814 . N=33 I A/B/C II Composite CR* 28 ( 85%) 32 ( 97%) CR 15 (45%) 19 (58%) CRh 11 (33%) 12 (36%) CRi 2 (6%) 1 (3%) Refractory 3 (9%) † - 1-yr EFS 75% (95% CI 61-92%) 1-yr OS 84% (95% CI 72-92%) *CR+CRh+CRi † 1 completed IA only

AbstractPurpose/objectiveWe compared the prognostic value of chest radiograph (CXR)‐ and computed tomography (CT)‐derived definition of large mediastinal adenopathy (LMA) in pediatric Hodgkin lymphoma (HL).Materials/methodsTotal 143 patients treated for stage IIIB/IVB HL on COG AHOD0831 were included in this study. Six definitions of LMA were investigated: (i) mediastinal mass ratio on CXR (MRCXR) > 1/3; (ii) mediastinal mass ratio on CT (MRCT) > 1/3; (iii) mediastinal mass volume on CT (MVCT) > 200 mL; (iv) normalized mediastinal mass volume (MVCT/thoracic diameter [TD]) > 1 mL/mm; (v) mediastinal mass diameter on CT (MDCT) > 10 cm; and (vi) normalized mediastinal mass diameter (MDCT/TD) > 1/3.ResultsMedian age at diagnosis was 15.8 years (range: 5.2–21.3 years). In patients with a slow early response (SER) to chemotherapy, MVCT > 200 mL, MDCT > 10 cm, and MDCT/TD > 1/3 were associated with worse relapse‐free survival (RFS) on MVA, while MRCXR > 1/3, MRCT > 1/3, and MVCT/TD > 1 mL/mm trended toward worse RFS; MDCT/TD was the most strongly prognostic for inferior RFS, with a hazard ratio of 6.41 for MDCT/TD > 1/3 versus ≤1/3 on MVA (p = .02).ConclusionLMA according to MVCT > 200 mL, MDCT > 10 cm, and MDCT/TD > 1/3 is associated with poor prognosis in advanced‐stage HL patients with SER. The normalized mediastinal diameter, MDCT/TD > 1/3 appears to be the strongest predictor of inferior RFS.

Abstract Objective To retrospectively identify patients with VEXAS syndrome (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic syndrome) among male patients with bone marrow vacuolization using a clinically applicable, targeted-screening approach. Methods Bone marrow reports from 1 May 2014 through 18 February 2022 were reviewed for documentation of cytoplasmic vacuolization. Patients with acute leukaemia, lymphoma, metastatic solid tumour, amyloidosis or POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, skin changes) syndrome were excluded, as were those without clinical records available for direct chart review. Cases were rated for suspicion of VEXAS syndrome using a 5-point scale based on the presence of laboratory findings, clinical features and treatment response. Patients with available DNA material and moderate (three patients) or high (four to five patients) suspicion were tested for somatic UBA1 variants associated with VEXAS syndrome. Results A total of 315 reports from 292 unique patients included documentation of vacuolization. Following exclusion criteria, 64 patients underwent direct medical chart review to assess likelihood of VEXAS syndrome, for which 21 patients met moderate to high suspicion. Available DNA was present in eight patients, seven (87.5%) of whom had a pathogenic somatic UBA1 variant consistent with VEXAS syndrome. The distribution of cytoplasmic vacuolization in the bone marrow biopsy reports among patients with VEXAS syndrome were erythroid and myeloid precursors (6/7), erythroid precursors only (1/7) and myeloid precursors only (0/7). Conclusion In this study, the utilization of a clinically applicable targeted-screening approach to test bone marrow specimens (with vacuolization) for the presence of previously undiagnosed VEXAS syndrome resulted in a positive detection rate of 87.5%.

Objective: We report the development and validation of a combined DNA/RNA next-generation sequencing (NGS) platform to improve the evaluation of pancreatic cysts. Background and Aims: Despite a multidisciplinary approach, pancreatic cyst classification, such as a cystic precursor neoplasm, and the detection of high-grade dysplasia and early adenocarcinoma (advanced neoplasia) can be challenging. NGS of preoperative pancreatic cyst fluid improves the clinical evaluation of pancreatic cysts, but the recent identification of novel genomic alterations necessitates the creation of a comprehensive panel and the development of a genomic classifier to integrate the complex molecular results. Methods: An updated and unique 74-gene DNA/RNA-targeted NGS panel (PancreaSeq Genomic Classifier) was created to evaluate 5 classes of genomic alterations to include gene mutations (e.g., KRAS, GNAS, etc.), gene fusions and gene expression. Further, CEA mRNA (CEACAM5) was integrated into the assay using RT-qPCR. Separate multi-institutional cohorts for training (n=108) and validation (n=77) were tested, and diagnostic performance was compared to clinical, imaging, cytopathologic, and guideline data. Results: Upon creation of a genomic classifier system, PancreaSeq GC yielded a 95% sensitivity and 100% specificity for a cystic precursor neoplasm, and the sensitivity and specificity for advanced neoplasia were 82% and 100%, respectively. Associated symptoms, cyst size, duct dilatation, a mural nodule, increasing cyst size, and malignant cytopathology had lower sensitivities (41–59%) and lower specificities (56–96%) for advanced neoplasia. This test also increased the sensitivity of current pancreatic cyst guidelines (IAP/Fukuoka and AGA) by >10% and maintained their inherent specificity. Conclusions: PancreaSeq GC was not only accurate in predicting pancreatic cyst type and advanced neoplasia but also improved the sensitivity of current pancreatic cyst guidelines.