Ansell, Stephen M.

Abstract Purpose: Regulatory T-cells (Treg) are essential to Tregs homeostasis and modulate the antitumor immune response in patients with lymphoma. However, the biology and prognostic impact of Tregs in splenic marginal zone lymphoma (SMZL) have not been studied. Experimental Design: Biopsy specimens from 24 patients with SMZL and 12 reactive spleens (rSP) from individuals without lymphoma were analyzed by using CITE-seq (cellular indexing of transcriptomes and epitopes by sequencing), CyTOF (mass cytometry) analysis, and flow cytometry to explore the phenotype, transcriptomic profile, and clinical significance of intratumoral Tregs and their subsets. The biological characteristics and cell signaling pathways of intratumoral Treg subsets were confirmed by in vitro functional assays. Results: We found that Tregs are more abundant in SMZL patients' spleens than rSP, and Tregs from patients with SMZL and rSP can be separated into CD161+Treg and CD26+Treg subsets. CD161+Tregs are increased in SMZL but have dysregulated immune function. We found that CD161+Treg and CD26+Tregs have unique gene expression and phenotypic profiles and are differentially correlated with patient outcomes. Specifically, increased CD161+Tregs are significantly associated with a favorable prognosis in patients with SMZL, whereas CD26+Tregs are associated with a poor prognosis. Furthermore, activation of the IL2/STAT5 pathway contributes to the induction of CD26+Tregs and can be reversed by STAT5 inhibition. Conclusions: IL2/STAT5-mediated expansion of CD26+Tregs contributes to a poor clinical outcome in SMZL and may represent a therapeutic opportunity in this disease.

Abstract Intravascular lymphoma (IVL) is a rare extranodal non‐Hodgkin lymphoma. We performed a retrospective analysis of 55 IVL patients who were treated at our institution 2003–2018. Median age at diagnosis was 68 years, and 64% were males. The most frequent presenting symptoms were skin rash 43% and weight loss 30%. MRI brain on IVL patients with CNS involvement (CNS‐IVL) showed multifocal involvement in 76% (13/17). 89% (17/19) of non‐CNS‐IVL patients with abnormal FDG‐PET had biopsy of an avid lesion resulting in definitive diagnosis. The top diagnostic biopsy site was the bone marrow (45%). 56% had multiorgan involvement. Based on CNS involvement, 36.5% (20/55) had CNS‐IVL and 63.5% (35/55) had non‐CNS‐IVL. CNS‐IVL group consists of clinically isolated CNS involvement (CNS‐only IVL) (22%;12/55) and mixed clinical CNS and peripheral site involvement (M‐IVL) (14.5%; 8/55). Non‐CNS‐IVL group consists of clinically isolated skin involvement (skin‐only IVL) (9%; 5/55) and peripheral IVL with or without skin involvement (P‐IVL); (54.5%; 30/55). Skin involvement was predominantly in the lower extremities. Pathologically, 89% (48/54) were B‐cell IVL. Rituximab + high‐dose methotrexate‐based regimen were used in 75% (12/16) of CNS‐IVL patients and RCHOP in 60% (17/28) of non‐CNS‐IVL patients. Estimated 5‐year progression free survival (PFS) and overall survival (OS) for the entire cohort were 38.6% and 52%, respectively. Skin‐only IVL was associated with excellent survival. Platelet count <150x10 9 /L, age > 60Y, and treatment without Rituximab were poor prognostic factors. Further research is necessary to identify novel therapies.

Abstract Previous studies have found that the prevalence of subtypes of T cells may be associated with patient outcomes, but a comprehensive analysis of the immune profile in the TM of FL has not been done. In the present study, we identified groups of FL patients with discretely unique TMEs and determined whether the T-cell phenotypes in the TME differed among groups. Using a cohort of 82 FL patients with biopsy specimens collected before treatment, we defined the type of TME based on the content of major lineages (T, B, monocytes/macrophages and NK cells) determined by CyTOF analysis. Hierarchical clustering of this cohort stratified patients into 4 groups with different TME: group 1 (G1) included patients with a high percentage of monocyte/macrophages/NK cells; patients from G2 and G3 were enriched for intratumoral T and B cells, respectively. Patients with intermediate numbers of T and B cells were included in G4. CITRUS analysis revealed that T-cell clusters with phenotypes expressing KLRG1, CD57, PD-1dim and rich in TEMRA cells were significantly more abundant in G1 when compared to G2, G3 or G4. In contrast, T-cell clusters with phenotypes containing CD127, CD45RA, CCR7 or PD-1high cells were significantly less abundant in G1 when compared to other groups. When compared to G3 or G4, 2 classes of T cell clusters, all from CD4+ T cells, were significantly more (CD127+KLRG1-) or less (CD57+PD-1high) abundant in G2, respectively. Clusters with a phenotype rich in short-lived effector cells (SLEC) (from CD8+) were upregulated in G3 when compared to G4. These results suggest that patient groups with distinct TME exhibited variable T-cell phenotypes. To determine the role of T-cell differentiation in predicting patient outcome in FL, we identified T-cell subsets using tSNE plots based on the expression of T-cell maturation markers. We identified 18 subsets (S1-S18) of T cells (11 from CD4, 6 from CD8 and 1 from CD4-CD8-) in each sample. Four subsets - S4 (CD4+TN), S5 (CD4+TCM), S7 (CD8+TN) and S10 (CD8+MEPCs) - were considered to be naïve cells or cells in the early stages of differentiation. Four additional subsets - S8 (CD57+TFH), S9 (CD4+TEXH), S13 (CD8+SLECs) and S17 (CD4+PD-1+Treg) - were memory cells with expression of surface markers indicting late-stage differentiation. We found that the 4 subsets (S4: p=0.08, S5: p=0.01, S7: p=0.04 and S10: p&lt;0.01) with an early-stage phenotype were associated with a favorable clinical outcome. In contrast, subsets (S8: p=0.02, S9: p=0.04, S13: p=0.07 and S17: p=0.06) with a late-stage differentiation phenotype had an unfavorable survival. Supporting this finding, we observed that increased numbers of CD45RA+ T cells correlated with a favorable survival. These results indicate that the differentiation stage may determine the role of T cells in predicting patient outcome in FL. Citation Format: Zhi-Zhang Yang, Hyo Jin Kim, Hongyan Wu, Xinyi Tang, Jordan Krull, Patrizia Mondello, Jose Villasboas, Anne Novak, Stephen Ansell. T-cell phenotype and differentiation vary in the tumor microenvironment of follicular lymphoma and are associated with patient outcome [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2529.

AbstractPurpose: Absolute lymphocyte count recovery at day 15 (ALC-15) post-autologous stem cell transplantation (ASCT) is a powerful prognostic indicator for survival for multiple hematologic malignancies and metastatic breast cancer. The relationship of ALC-15 with clinical outcomes in primary systemic amyloidosis is unknown.Experimental Design: We evaluated 145 consecutive patients with primary systemic amyloidosis who underwent ASCT at the Mayo Clinic from 1996 to 2003. The ALC-15 threshold was set at 500 cells/μL based on our previous observations.Results: The median patient follow-up was 22 months (range, 3-87 months). Higher hematologic complete response was observed in patients with an ALC-15 ≥ 500 cells/μL compared with patients with an ALC-15 &lt; 500 cells/μL (41% versus 21%, P &lt; 0.0008, respectively). The median overall survival and progression-free survival times were significantly better for the 59 patients that achieved an ALC-15 ≥ 500 cells/μL compared with 86 patients with ALC-15 &lt; 500 cells/μL (not reached versus 53 months, P &lt; 0.0003 and not reached versus 27 months, P &lt; 0.0001, respectively). Multivariate analysis showed ALC-15 to be an independent prognostic factor for overall survival and progression-free survival.Conclusions: ALC-15 ≥ 500 cells/μL is associated with significantly improved clinical outcomes following ASCT in patients with primary systemic amyloidosis.

LBA7564 Background: Patients with r/r B-NHL have a dismal prognosis. DIAL (Dual Immunomodulation in Aggressive Lymphoma) was a multi-center randomized phase II study testing the efficacy of nivolumab (PD-1 inhibitor) plus varlilumab (CD27 agonist) in this population. Methods: Patients were randomized (1:1) to nivolumab (240 mg IV every 2 weeks for 4 months, 480 mg IV monthly thereafter; group 1) alone or combined with varlilumab (3 mg/kg IV monthly; group 2). Cross-over (group 1 to 2) was allowed for progression. Primary endpoint was overall response (ORR) per LYRIC criteria. A sample size of 48 patients per arm would provide 80% power to detect increase in ORR from 25% to 45% using a one-sided test (p = 0.15). Pre-specified interim analysis occurred after half of the patients completed first radiologic assessment. Secondary endpoints included overall survival (OS), progression-free survival (PFS), and adverse events (AEs). Exploratory endpoints included tumor genomic assessment and immune profiling of blood and tumor. Results: 53 patients were enrolled (27 in group 1; 26 in group 2). Interim analysis included 24 patients from each arm. Mean age was 65.2 years, 34 (70.8%) were male, and 36 (75%) received prior CAR-T cell therapy. Baseline characteristics were balanced between arms. Grade ≥ 3 AEs were observed in 8 (33.3%) and 7 (30.4%) of patients in groups 1 and 2, respectively. Common AEs (> 5%) of any grade included fatigue, lymphopenia, diarrhea, rash. There were no treatment-associated deaths. Toxicity profile was similar between arms. Table summarizes efficacy outcomes. ORR was achieved in 6 patients (12.5%), not statistically different between arms; 4 responses were complete. Seven patients crossed over (1 responded after crossing). Median OS (8.6 vs 7.3 months; p = 0.39) and PFS (2.7 vs 1.4 months; p = 0.06) were similar between arms. Subgroup analysis of patients with prior CAR-T cell therapy showed similar ORR (5/36; 14%), not statistically different between arms. Correlative analysis results will be presented at conference. The trial met futility criterion on interim analysis and enrollment ceased based on pre-specified stopping rule. Conclusions: Dual immunomodulatory therapy did not enhance anti-tumor activity in patients with aggressive B-NHL compared to nivolumab alone. Response rates were low and consistent with previous data using PD-1 inhibitors in this population. Prior therapy with CAR-T cell does not seem to sensitize patients to PD-1 blockade. Toxicity profile was acceptable and dual therapy did not increase the rate of AEs. Clinical trial information: NCT03038672. [Table: see text]

e19562 Background: Considerable healthcare resource utilization and financial burden have been associated with the treatment of Waldenstrom Macroglobulinemia (WM); however, the impact of health insurance status on patient outcomes has not been explored. We aimed to assess the insurance-based outcome relationship in WM using the National Cancer Database (NCDB). Methods: We analyzed patient-level data obtained from the NCDB, a database representing more than 70% of newly diagnosed cancer cases nationwide. All newly diagnosed WM cases (n = 8540) between 2004 to 2017 were identified. Only patients who underwent treatment were included. Insurance status was recorded by assessing the primary payer at the time of diagnosis. Due to Medicare eligibility criteria, age-based (< 65 and ≥65 years) stratified analysis was conducted. Cox proportional hazards model was utilized to analyze survival. Time-to-event analysis was conducted based on date-of-diagnosis using the Kaplan-Meier method and log-rank test. Results: Analysis was conducted on 3878 patients after meeting inclusion criteria, with a median follow-up time of 54.6 months. Among patients < 65 years (n = 1249; median age: 58 years; male: 62.4%), those with non-private insurance had inferior survival on multivariate analysis (Table) after adjusting for patient demographics, comorbidities, income, education, treatment center characteristics, and treatment start time. Significant overall survival (OS) differences were seen in those < 65 years (log-rank p < 0.001), with 5-year OS highest among patients with private insurance 91.2%, compared to Medicaid 79.8%, uninsured 77.4%, and Medicare 70.2%. In patients < 65 years, compared to private insurance, uninsured patients were more likely to be of Black race, reside in lower income areas, and be treated at non-academic centers (all p < 0.05). Both Medicaid and Medicare patients < 65 years were more likely to have a higher Charlson-Deyo comorbidity index (> 1) and live in areas of lower educational attainment and household income compared to private insurance (all p < 0.05). In patients ≥65 years (n = 2629; median age: 75 years; 60.6% males), no insurance-based OS (log-rank p = 0.096) differences were seen. Conclusions: Based on our study, significant insurance-based disparities exist in WM, where patients < 65 years old who are uninsured, or non-privately insured are at a higher risk of mortality. While the root cause of these differences is not fully elucidated, efforts should focus on ensuring that all patients have equal access to care regardless of primary payer status.[Table: see text]

e19533 Background: Pneumocystis pneumonia (PJP) is a catastrophic infection seen in the context of low CD4 counts. Brentuximab vedotin (BV) is a drug antibody conjugate targeting CD30 and is used to treat patients with Hodgkin’s lymphoma (HL) and T-cell lymphoma (TCL). PJP prophylaxis is not currently recommended for patients receiving BV-based treatment despite co-expression of CD30 on CD4 cells. The frequency of PJP following BV remains poorly defined. Methods: We evaluated patients who received BV between January 1, 2011 and October 31, 2021 at Mayo Clinic for the development of PJP. Patient demographics and clinical characteristics including underlying disease, chemotherapy regimen, absolute lymphocyte count (ALC), and steroid exposure were collected. Patients who developed PJP more than 3 months after their last BV exposure were excluded. Results: Of 402 BV recipients identified, 63 received PJP prophylaxis and were omitted. Fourteen of the 339 (4.1%) not on prophylaxis developed PJP following BV. Those infected had a median age of 61 (22-87), 71% were male. The most common diagnoses were HL, TCL, and primary mediastinal B-cell lymphoma at rates of 57%, 21%, and 14% respectively. Therapy regimens included BV monotherapy, BV-CHP, and BV-AVD at rates of 43%, 21%, and 14% respectively. BV represented median 2nd line of therapy (1-10) and patients received median of 3 doses (1-10) prior to PJP diagnosis. Patients with PJP had median ALC of 620 (370-3500). 71.4% (10/14) had an ALC less than 750 and among those with ALC greater than 1000, 75% (3/4) had underlying diagnosis of HL. Three patients had CD4 count measured at time of PJP diagnosis with median value of 157 (5-175). 57.1% (8/14) had no steroid exposure beyond the treatment regimen. 14.3% (2/14) were on chronic doses of 5mg prednisone for autoimmune conditions. Short bursts of steroids (prednisone 40 mg) prior to PJP were seen in 21.4% (3/14) with median exposure of 8 days (7-10). One patient had prolonged steroid exposure but was weaned off 17 days prior to PJP diagnosis. 71.4% were older than 50 years at time of PJP. Conclusions: We observed rates of PJP above the commonly accepted threshold of 3.5% for recommending prophylaxis. Among patients with an ALC greater than 1000, 75% had HL raising the question of a qualitative defect in immunity. Close ALC monitoring is recommended for patients receiving BV with a low threshold to institute PJP prophylaxis, especially amongst those older than 50 or with a diagnosis of HL.[Table: see text]

e19532 Background: The traditional approach to the treatment of early-stage classical Hodgkin lymphoma (cHL) has been combined modality therapy (CMT) with both chemotherapy and radiotherapy (RT). CMT has shown improved disease control, but RT can lead to long-term adverse effects, including secondary malignancies and cardiac toxicity. Multiple clinical trials have assessed treatment de-escalation strategies to chemotherapy-alone regimens, but results are conflicting. We aimed to assess the real-world implications of these trials by comparing patient outcomes based upon treatment with CMT or chemotherapy-alone. Furthermore, we proposed to assess differences in treatment outcomes stratified by disease bulk, favorable/unfavorable disease, and PET2 response. Methods: We conducted a retrospective, multi-center cohort study of consecutive adult patients with early-stage (stage IA-IIB) cHL treated between January 2010-December 2020. Baseline characteristics, treatment modality, and outcomes were abstracted by chart review. Available PET2 scans (n=110) were independently reviewed by a blinded nuclear radiologist. Deauville score (DS) ≥4 was characterized as positive (+), and DS≤3 negative (-). All analysis was conducted using intention-to-treat principles based upon the initial treatment plan (CMT or chemotherapy-alone). Results: In 125 patients [58% male, median age 34 (range, 18-78)] with early-stage cHL, CMT was intended in 63 (50%) patients, with chemotherapy-alone in 62 (50%). Bulky disease was observed in 43 (34%), unfavorable disease in 81 (65%), and 15 (14%) were found to be PET2+. With median follow-up of 59.8 months (95%CI, 48.6 to 71.0), 5 (4%) deaths occurred, and 17 (14%) patients had relapsed/refractory disease. No significant differences in overall survival (OS) were seen based upon treatment intention. However, there was substantially reduced progression-free survival (PFS) (Table) with chemotherapy-alone in the whole cohort, and also in those with bulky, unfavorable, and PET2+ disease. No significant PFS differences were seen based upon treatment intention for patients with non-bulky, favorable, or PET2- disease. Conclusions: Based on our real-world experience, CMT appears particularly beneficial for patients with bulky disease, unfavorable prognostic factors, and PET2+ disease. However, while recent trials showed a benefit of CMT in non-bulky, favorable and PET2- patients, chemotherapy-alone may be comparable for these patients in actual clinical practice.[Table: see text]

TPS7586 Background: EO2463 is a therapeutic vaccine designed to activate existing commensal bacteria-specific memory T cells that cross-react with B cell markers in order to drive anti-tumor immune activity against B-cell malignancies. The four microbial-derived, synthetically produced peptides contained in EO2463 (OMP72, OMP64, OMP65, and OMP66), correspond to cytotoxic CD8 T cell HLA-A2 restricted epitopes, and exhibit molecular mimicry with the B cell markers CD20, CD22, CD37, and CD268 (BAFF-receptor), respectively. In pre-clinical models, these peptides can generate strong immune responses and specifically stimulate cross-reactive cytotoxic CD8 T cells to recognize the chosen B cell targets. EO2463 also contains a CD4 helper peptide referred to as universal cancer peptide 2, derived from the human telomerase reverse transcriptase catalytic subunit. The present study is a first-in-human clinical trial of this microbiome-derived peptide therapeutic cancer vaccine approach in patients with follicular lymphoma (FL) and marginal zone lymphoma (MZL). Methods: This four-cohort phase 1/2 trial will investigate EO2463 monotherapy, and combinations of EO2463/lenalidomide (EL), EO2463/rituximab (ER), and EO2463/lenalidomide/rituximab (ER2), for treatment of patients with FL and MZL. Cohort 1 is a safety lead-in dose-finding in patients with relapsed/refractory (RR) disease, with a 3-by-3 design to establish the recommended phase 2 dose (RP2D) for EO2463 monotherapy and to confirm the safety of the RP2D for combination schedules of EL, and ER2. After the recommended EO2463 monotherapy dose is established, cohorts 2, 3, and 4 will open to accrual. Cohort 2 will investigate EO2463 monotherapy in patients with newly diagnosed FL/MZL who are not in need of treatment; cohort 3 will investigate EO2463 monotherapy, followed by ER in patients with limited tumor burden who need treatment, and cohort 4 will further investigate EL, followed by ER2 in the RR setting. EO2463 will be administered SC 4 times at 2-week intervals, followed by continued booster administrations every 4 weeks for 9 (Cohorts 2 and 3) or 12 (Cohorts 1 and 4) months. Inclusion/exclusion criteria, and the design and schedule of the intense immune and safety monitoring will be presented. The safety lead-in dose-finding is currently ongoing, and no safety concerns have been observed thus far. Clinical trial information: NCT04669171.

7566 Background: Parenteral limited-duration BR chemoimmunotherapy and continuous orally administered Ibr, a Bruton tyrosine kinase inhibitor, dominate the treatment landscape of WM, a rare B cell lymphoma. No trials have assessed the comparative effectiveness of these 2 vastly different approaches. We conducted a multiinstitutional, international, collaborative study to compare BR and single-agent Ibr in patients (pts) with treatment naïve (TN) WM. Methods: Data from 347 pts with active TN WM, seen between 2011 and 2021 in the US and Europe, were analyzed. The pts on rituximab maintenance were excluded. The modified IWWM-6 criteria (based on IgM alone) were used for response assessment. All time-to-event analyses were performed from the frontline therapy initiation, using the Kaplan-Meier method. Results: The median age of the pts treated with BR (n=208) and Ibr (n=139) was 66 (range 40-86) years (y) and 69 (39-97) y, respectively, (p=0.005). With a median follow up of 4.2 y (95% CI 3.8-4.5), the 4-y progression free survival (PFS) was 73% in each group, p=0.6, and 4-y overall survival (OS) was 94% (95% CI 91-98) in the BR group versus ( v) 82% (95% CI 75-90) in the Ibr group, p=0.01. In a bivariate analysis adjusting for age and the treatment type, only age emerged as a predictor for OS (HR 7.2, p=0.0001). Therefore, a 1:1 age-matched analysis of 246 pts who received Ibr (n=123) or BR (n=123) was performed. Pts with a known MYD88WT status who had received Ibr and their age matched controls on BR were excluded. The international prognostic scoring system (IPSS) WM was comparable between the 2 groups (Table). A higher proportion of pts on BR attained very good partial or deeper response (≥VGPR) as the best response in comparison to the pts on Ibr (Table). The 4-y PFS for the BR and Ibr groups was similar [72% (95% CI 63-82) v 78% (95% CI 70-87), p=0.14] and 4-y OS was 95% (95% CI 91-99) with BR v 86% (95% CI 80-93) with Ibr (p=0.3). Premature discontinuation, during active treatment, due to adverse effects (AEs) or lack of response was noted in 13% and 33% of pts on BR and Ibr, respectively. A detailed assessment of the AEs will be presented at the meeting. Conclusions: Both BR and Ibr lead to comparable outcomes in pts with TN WM, although deeper responses are attained with BR. These findings require confirmation in prospective studies. For pts who harbor MYD 88L265P mutation, selection between the 2 approaches should be dictated by their potential toxicities, pt comorbidities, pt/clinician preference (parenteral fixed-duration v continuous oral) and access to therapies. [Table: see text]