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Epstein-Barr virus–positive (EBV-positive) B-cell lymphomas are common in immunocompromised patients and remain an unmet medical need. Here we report that MDM2 inhibitors (MDM2is) navtemadlin and idasanutlin have potent in vivo activity in EBV-positive B-cell lymphoma established in immunocompromised mice. Tumor regression was observed in all 5 EBV-positive xenograft–associated B-cell lymphomas treated with navtemadlin or idasanutlin. Molecular characterization showed that treatment with MDM2is resulted in activation of p53 pathways and downregulation of cell cycle effectors in human lymphoma cell lines that were either EBV-positive or had undetectable expression of BCL6, a transcriptional inhibitor of the TP53 gene. Moreover, treatment with navtemadlin resulted in tumor regression and prevented systemic dissemination of EBV-positive lymphoma derived from 2 juvenile patients with posttransplant lymphoproliferative diseases, including 1 whose tumor was resistant to virus-specific T-cell therapy. These results provide proof-of-concept for targeted therapy of EBV-positive lymphoma with MDM2is and the feasibility of using EBV infection or loss of BCL6 expression to identify responders to MDM2is.

PURPOSE Most patients with mantle cell lymphoma (MCL) are older. In this study, we investigated the efficacy and safety of a chemotherapy-free combination with ibrutinib and rituximab (IR) in previously untreated older patients with MCL (age ≥ 65 years). METHODS We enrolled 50 patients with MCL in this single-institution, single-arm, phase II clinical trial ( NCT01880567 ). Patients with Ki-67% ≥ 50% and blastoid morphology were excluded. Ibrutinib was administered with rituximab up to 2 years with continuation of ibrutinib alone. The primary objective was to assess the overall response rate and safety of IR. In evaluable samples, whole-exome sequencing and bulk RNA sequencing from baseline tissue samples were performed. RESULTS The median age was 71 years (interquartile range 69-76 years). Sixteen percent of patients had high-risk simplified MCL international prognostic index. The Ki-67% was low (< 30%) in 38 (76%) and moderately high (≥ 30%-50%) in 12 (24%) patients. The best overall response rate was 96% (71% complete response). After a median follow-up of 45 months (interquartile range 24-56 months), 28 (56%) patients came off study for various reasons (including four progression, 21 toxicities, and three miscellaneous reasons). The median progression-free survival and overall survival were not reached, and 3-year survival was 87% and 94%, respectively. None of the patients died on study therapy. Notably, 11 (22%) patients had grade 3 atrial fibrillation. Grade 3-4 myelosuppression was seen in < 5% of patients. Differential overexpression of CCND1, BIRC3, BANK1, SETBP1, AXIN2, and IL2RA was noted in partial responders compared with patients with complete response. CONCLUSION IR combination is effective in older patients with MCL. Baseline evaluation for cardiovascular risks is highly recommended. Randomized trial is needed for definitive conclusions.

B cell malignancies pose challenges due to therapeutic resistance and repeated relapse. Advances in adoptive cellular therapies including chimeric antigen receptor (CAR)-T cells have the potential to transform the treatment landscape in hematological and solid tumor cancers. Improvements in constructs of CAR-T have improved specificity in targeting malignant cells. Multiple clinical trials have demonstrated the efficacy of CAR-T and other cellular treatments. In spite of advances in cellular therapies, hurdles in managing toxicities and lingering resistance remain. This review aims to summarize current innovations in adoptive cellular therapies and introduces future paths of discovery that will enhance these therapies in the era of precision oncology.

Mantle cell lymphoma (MCL) is an uncommon subtype of non-Hodgkin lymphoma in which immunochemotherapy, with or without high-dose therapy, and autologous stem cell transplantation remain standard frontline therapies. Despite their clear efficacy, patients inevitably relapse and require subsequent therapy. In this review, we discuss the key therapeutic approaches in the management of relapsed MCL, covering in depth the data supporting the use of covalent Bruton tyrosine kinase (BTK) inhibitors at first or subsequent relapse. We describe the outcomes of patients progressing through BTK inhibitors and discuss the mechanisms of covalent BTKi resistance and treatment options after covalent treatment with BTKi. Options in this setting may depend on treatment availability, patient’s and physician’s preference, and the patient’s age and comorbidity status. We discuss the rapid recent development of anti-CD19 chimeric antigen receptor T-cell therapy, as well as the utility of allogenic stem cell transplantation and novel therapies, such as noncovalent, reversible BTK inhibitors; ROR1 antibody drug conjugates; and bispecific antibodies.

CD5+ diffuse large B-cell lymphoma (DLBCL), NOS represents a distinct subset of DLBCL associated with poorer outcomes and extranodal disease. We analyzed characteristics and outcomes for 10...

Enhancer of zeste homolog 2 (EZH2) is a catalytic component of the polycomb repressive complex 2 (PRC2) which reduces gene expression via trimethylation of a lysine residue of histone 3 (H3K27me3). Expression of EZH2 has not been assessed systematically in mantle cell lymphoma (MCL). Expression of EZH2 was assessed by immunohistochemistry in 166 patients with MCL. We also assessed other PRC2 components and H3K27me3. Fifty-seven (38%) of MCL patients were positive for EZH2 using 40% cutoff. EZH2 expression was associated with aggressive histologic variants (65% vs. 29%, p < 0.001), high Ki-67 proliferation rate (median, 72% vs. 19%, p < 0.001), and p53 overexpression (43% vs. 2%, p < 0.001). EZH2 expression did not correlate with expression of other PRC2 components (EED and SUZ12), H3K27me3, MHC-I, and MHC-II. Patients with EZH2 expression (EZH2+) had a poorer overall survival (OS) compared with patients without EZH2 expression (EZH2-) (median OS: 3.9 years versus 9.4 years, respectively, p < 0.001). EZH2 expression also predicted a poorer prognosis in MCL patients with classic histology (median OS, 4.6 years for EZH2+ and 9.6 years for EZH2-negative, respectively, p < 0.001) as well as aggressive histology (median OS, 3.7 years for EZH2+ and 7.9 years for EZH2-negative, respectively, p = 0.046). However, EZH2 expression did not independently correlate with overall survival in a multivariate analysis. Gene expression analysis and pathway enrichment analysis demonstrated a significant enrichment in cell cycle and mitotic transition pathways in MCL with EZH2 expression. EZH2 expression detected by immunohistochemistry is present in 38% of MCL cases and it is associated with high proliferation rate, p53 overexpression, aggressive histologic variants, and poorer OS. Based on gene expression profiling data, EZH2 expression could potentiate cell cycle machinery in MCL. These data suggest that assessment of EZH2 expression could be useful to stratify MCL patients into low- and high-risk groups.

Context Despite the marked efficacy of covalent BTK inhibitors (BTKi) in MCL, WM, and MZL, the development of resistance and discontinuation for adverse events can lead to treatment failure. Low oral bioavailability or short half-life of these agents can lead to suboptimal BTK target coverage and ultimately result in acquired resistance in some patients (pts). Pirtobrutinib (LOXO-305) is a highly selective, non-covalent BTKi that inhibits both WT and C481-mutated BTK with equal, low nM potency. Objective To evaluate safety and efficacy of pirtobrutinib in pts with MCL/NHLs. Design BRUIN is an ongoing multi-center phase 1/2 trial (NCT03740529). Enrollment was initiated 21 March 2019. Setting Global: community hospitals, academic medical centers. Patients Previously treated pts with advanced B-cell malignancies. Interventions Oral pirtobrutinib (7 dose escalation levels: 25–300mg once daily) in 28-day cycles. Main Outcomes Measures Determining the maximum tolerated dose/recommended phase 2 dose (RP2D), safety profile, and efficacy based on response assessment using disease-specific criteria per protocol. Results As of 27 September 2020, 323 pts with B-cell malignancies (170 CLL/SLL, 61 MCL, 26 WM, and 66 other B-cell lymphomas) were treated on 7 dose levels (25–300mg QD). Pirtobrutinib demonstrated high oral exposures, with doses ≥100 mg QD exceeding the BTK IC90 for the entirety of the dosing interval. No DLTs occurred. The only TEAEs, regardless of attribution or grade in ≥10% of pts (n=323), were fatigue (20%), diarrhea (17%) and contusion (13%). A RP2D of 200mg QD was selected. At the efficacy cutoff date, 35 (57%) MCL pts, 18 (69%) WM pts, and 34 (52%) other NHL pts remained on therapy. Among the 52 efficacy evaluable prior BTKi treated MCL pts, the ORR was 52%. Among the 19 efficacy evaluable pts with WM, the ORR was 68%. For the other 55 efficacy evaluable NHL pts, ORR was 24% (DLBCL), 50% (FL), 22% (MZL), and 75% (Richter's transformation). Conclusion Pirtobrutinib demonstrated promising efficacy in MCL and other NHL pts, was well-tolerated and exhibited a wide therapeutic index.

Blastoid and pleomorphic mantle cell lymphomas (MCLs) are variants of aggressive histology MCL (AH-MCL). AH-MCL can arise de novo (AH-DN) or transform from prior classic variant MCL (AH-t). This study is the first integrated analysis of clinical and genomic characteristics of AH-MCL. Patient characteristics were collected from diagnosis (AH-DN) and at transformation (AH-t). Survival after initial diagnosis (AH-DN) and after transformation (AH-t) was calculated. Regression tree analysis was performed to evaluate prognostic variables and in univariate and multivariate analyses for survival. Whole-exome sequencing was performed in evaluable biopsy specimens. We identified 183 patients with AH-MCL (108 were AH-DN, and 75 were AH-t; 152 were blastoid, and 31 were pleomorphic). Median survival was 33 months (48 and 14 months for AH-DN and AH-t, respectively; P = .001). Factors associated with inferior survival were age (≥72 years), AH-t category, Ki-67 ≥50% and poor performance status. AH-t had a significantly higher degree of aneuploidy compared with AH-DN. Transformed MCL patients exhibited KMT2B mutations. AH-MCL patients with Ki-67 ≥50% had exclusive mutations in CCND1, NOTCH1, TP53, SPEN, SMARCA4, RANBP2, KMT2C, NOTCH2, NOTCH3, and NSD2 compared with low Ki-67 (

Inhibition of the B-cell receptor (BCR) signaling pathway is highly effective in B-cell neoplasia through Bruton tyrosine kinase inhibition by ibrutinib. Ibrutinib also disrupts cell adhesion between a tumor and its microenvironment. However, it is largely unknown how BCR signaling is linked to cell adhesion. We observed that intrinsic sensitivities of mantle cell lymphoma (MCL) cell lines to ibrutinib correlated well with their cell adhesion phenotype. RNA-sequencing revealed that BCR and cell adhesion signatures were simultaneously downregulated by ibrutinib in the ibrutinib-sensitive, but not ibrutinib-resistant, cells. Among the differentially expressed genes, RAC2, part of the BCR signature and a known regulator of cell adhesion, was downregulated at both the RNA and protein levels by ibrutinib only in sensitive cells. RAC2 physically associated with B-cell linker protein (BLNK), a BCR adaptor molecule, uniquely in sensitive cells. RAC2 reduction using RNA interference and CRISPR impaired cell adhesion, whereas RAC2 overexpression reversed ibrutinib-induced cell adhesion impairment. In a xenograft mouse model, mice treated with ibrutinib exhibited slower tumor growth, with reduced RAC2 expression in tissue. Finally, RAC2 was expressed in ∼65% of human primary MCL tumors, and RAC2 suppression by ibrutinib resulted in cell adhesion impairment. These findings, made with cell lines, a xenograft model, and human primary lymphoma tumors, uncover a novel link between BCR signaling and cell adhesion. This study highlights the importance of RAC2 and cell adhesion in MCL pathogenesis and drug development.

Venetoclax is effective in relapsed patients with mantle cell lymphoma (MCL). Mechanisms of resistance to venetoclax in MCL are poorly understood. We describe the clinical outcomes and genomic characteristics of 24 multiply relapsed patients (median of five prior lines of therapy) who received venetoclax-based therapies; 67% had progressed on BTK inhibitors (BTKi) and 54% had blastoid or pleomorphic histology. Median follow up after venetoclax treatment was 17 months. The overall response rate was 50% and complete response (CR) rate was 21%, 16 patients had progressed and 15 died. The median progression free, overall and post venetoclax survival were 8, 13.5 and 7.3 months respectively. Whole-exome sequencing (WES) was performed on samples collected from seven patients (including five pairs; before starting venetoclax and after progression on venetoclax). The SMARCA4 and BCL2 alterations were noted only after progression, while TP53, CDKN2A, KMT2D, CELSR3, CCND1, NOTCH2 and ATM were altered 2-4-fold more frequently after progression. In two patients with serial samples, we demonstrated clonal evolution of novel SMARCA4 and KMT2C/D mutations at progression. Mutation dynamics in venetoclax resistant MCL is demonstrated. Our data indicates that venetoclax resistance in MCL is predominantly associated with non-BCL2 gene mutations. Further studies are ongoing in MCL patients to evaluate the efficacy of venetoclax in combination with other agents and understand the biology of venetoclax resistance in MCL.

Mantle cell lymphoma (MCL) is an incurable rare subtype of non-Hodgkin lymphoma and is subject to relapse and therapeutic resistance. Molecular aberrations in MCL affect pathogenesis, prognosis, and therapeutic response. In this systematic review, we searched 3 databases and selected 32 articles that described mutations in MCL patients. We then conducted a meta-analysis using a Bayesian multiregression model to analyze patient-level data in 2127 MCL patients, including prevalence of mutations. In tumor or bone marrow samples taken at diagnosis or baseline, ATM was the most frequently mutated gene (43.5%) followed by TP53 (26.8%), CDKN2A (23.9%), and CCND1 (20.2%). Aberrations were also detected in IGH (38.4%) and MYC (20.8%), primarily through cytogenetic methods. Other common baseline mutations were NSD2 (15.0%), KMT2A (8.9%), S1PR1 (8.6%), and CARD11 (8.5%). Our data also show a change in mutational status from baseline samples to samples at disease progression and present mutations of interest in MCL that should be considered for future analysis. The genes with the highest mutational frequency difference (>5%) are TP53, ATM, KMT2A, MAP3K14, BTK, TRAF2, CHD2, TLR2, ARID2, RIMS2, NOTCH2, TET2, SPEN, NSD2, CARD11, CCND1, SP140, CDKN2A, and S1PR1. These findings provide a summary of the mutational landscape of MCL. The genes with the highest change in mutation frequency should be included in targeted next-generation sequencing panels for future studies. These findings also highlight the need for analysis of serial samples in MCL. Patient-level data of prevalent mutations in MCL provide additional evidence emphasizing molecular variability in advancing precision medicine initiatives in MCL.

The natural history of mantle cell lymphoma (MCL) undergoing chemotherapy is a cyclical pattern of remission followed by recurrence of disease due to acquired chemotherapy resistance. The median age of the occurrence of MCL is 65 years, so half of the newly diagnosed MCL patients are considered “elderly.” The tolerance to long-term chemotherapy in elderly patients is decreased; hence, the response to frontline therapy used is of paramount importance. We hope that our review may guide clinicians in treating such populations in a more personalized and evidence-based manner. In the older patients with risk variables, frontline treatment is determined according to different body status of fit, unfit or compromised, and frail. In the fit patients, the pursuit of remission and prolongation of survival might currently justify the use of more intense and toxic therapies. For unfit or compromised older patients, disease control needs to be prioritized, maintaining a balance between the benefits and toxicities of the treatment. For frail patients, tolerance of treatment and minimizing myelotoxicity should be the primary focus. “Chemotherapy-free” regimens are likely to be considered as the first-line strategy for this population. On the other hand, in the older MCL population without risk variables, observation or “watch and wait” can prevent overtreatment. Furthermore, more clinical trials and research studies on novel agents and targeted therapies need to be translated into the general population to provide optimal treatment and to guide personalized treatment. Implications for Practice This review emphasizes the importance of frontline therapies for older MCL patients. MCL patients commonly experience a cyclical pattern of remission followed by recurrence of disease due to acquired chemotherapy resistance. As a special population, elderly patients have various comorbidities and decreased organ function, which may reduce the chances of undergoing treatment for recurrent disease. Thus, this older population of patients with MCL should be treated separately and exceptionally. So far, systematic reviews with regard to frontline treatment for older patients with MCL have not been encountered, but the hope is that this review may guide clinicians in treating such populations in a more personalized and evidence-based manner.

Osteocartilaginous differentiation in malignant melanoma is rare and can pose a diagnostic challenge. In previously reported cases, melanomas were predominantly located on acral and mucosal sites, with osteocartilaginous differentiation present in either primary or recurrent lesions. We report a case of a 52-year-old female with malignant melanoma located on the right upper back exhibiting osteosarcomatous differentiation only in the axillary lymph node metastasis. This case serves to highlight that the divergent differentiation can occur in lymph node metastases while being absent in the primary lesion. The patient's medical history, careful histological examination, and immunohistochemistry may be necessary for establishing the correct diagnosis.

Ibrutinib has shown significant activity in patients with relapsed or refractory mantle cell lymphoma (RR-MCL). We report the long-term outcome and safety profile of a single-centre, single arm, open-label, phase 2 study of RR-MCL treated with IR. Overall, the median follow-up time was 47 months (range 1-52 months), median duration on treatment was 16 months (range 1-53 months) and median number of treatment cycles was 17 (range 1-56). Twenty-nine patients (58%) achieved complete remission and of these, 12 patients continue on study. Thirty-eight patients discontinued treatment, 14 due to disease progression (2 transformed). Patients with blastoid morphology, high risk MCL International Prognostic Index score and high Ki67% had inferior survival. The commonest grade 1-2 toxicities were fatigue, diarrhoea, nausea, arthralgias and myalgias. None had long term toxicities. Median progression-free survival was 43 months. Eighteen patients (36%) died (14 deaths were MCL-related). The median overall survival has not been reached. Treatment with IR can provide durable remissions in a subset of patients with RR-MCL, especially those with low Ki67%. The possible benefit of adding other therapies in combination with IR in RR-MCL is under exploration.

CD30 and programmed cell death protein 1 (PD-1) are two ideal therapeutic targets in classical Hodgkin lymphoma (cHL). The CD30 antibody-drug conjugate (ADC) brentuximab vedotin and the PD-1 antibodies nivolumab and pembrolizumab are highly efficacious in treating relapsed and/or refractory cHL. Ongoing studies are evaluating their efficacy in earlier lines of therapy and have demonstrated encouraging results. These agents are expected to further change the landscape of cHL management. Increased cure rates and reduced long-term toxicity from traditional chemotherapy and radiotherapy are likely with the emergence of these novel targeted therapies.

Distinction of chilblain lupus erythematosus (CLE) from idiopathic perniosis (IP) could predict an underlying connective tissue disease; however, histopathologic discrimination of the two is difficult. Increased CD123 plasmacytoid dendritic cells and CD30 lymphocytes have been demonstrated in various forms of cutaneous lupus erythematosus and IP, respectively. To our knowledge, CD123 and CD30 have not been examined in CLE. Our objective was to identify helpful histopathologic and immunohistochemical features in distinguishing CLE and IP. Skin biopsies classified as CLE (n = 20) and IP (n = 39) based on clinicopathologic correlation were collected from 2000 to 2015. Various histopathologic features were examined on hematoxylin and eosin and alcian blue stains. CD123 and CD30 immunostains were performed and characterized. We identified dermal interstitial fibrin exudate (P = 0.0352) and increased dermal mucin (P = 0.0002) as features significantly associated with CLE. Other histopathologic features and CD123 failed to distinguish between groups. CD30 lymphocytes were sparse in all cases. Despite being the largest series of CLE and IP to date, the number of CLE cases in this study remained relatively limited, and some patients in the IP group may have yet to develop diagnostic features of systemic lupus erythematosus. In conclusion, histopathologic distinction between CLE and IP remains challenging. Interstitial fibrin and abundant dermal mucin help favor CLE. The number and distribution of CD123 plasmacytoid dendritic cells and CD30 lymphocytes have no discriminatory role.

Background: Covalent Bruton's Tyrosine Kinase (BTK) inhibitors (BTKi) have transformed the management of relapsed mantle cell lymphoma (MCL), but these treatments are not curative and the majority of patients will require additional treatment. Covalent BTKi share pharmacologic liabilities (e.g. low oral bioavailability, short half-life) that collectively may lead to suboptimal BTK target coverage especially in rapidly proliferating tumors with high BTK protein turnover such as MCL. To address these limitations, pirtobrutinib, a highly selective, non-covalent BTKi that inhibits both wild type (WT) and C481-mutated BTK with equal low nM potency was developed. In the phase 1/2 BRUIN study, pirtobrutinib achieved pharmacokinetic exposures that exceeded its BTK IC96 at trough, was well tolerated, and demonstrated promising efficacy in heavily pretreated, poor-prognosis MCL patients, most of whom had prior treatment with a covalent BTKi (Mato et al. Lancet 2021;397,10277:892-901). The purpose of this randomized study is to demonstrate the superiority of pirtobrutinib compared to investigator's choice of covalent BTKi in patients with previously treated MCL. Study Design and Methods: BRUIN MCL-321 is a randomized, open-label, global phase 3 study comparing pirtobrutinib monotherapy versus investigator's choice of covalent BTKi monotherapy (ibrutinib, acalabrutinib, or zanubrutinib) in patients with previously treated, BTKi naïve MCL. Approximately 500 patients will be randomized 1:1. Randomization will be stratified by sMIPI risk (low/intermediate vs high), comparator BTKi (ibrutinib vs acalabrutinib/ zanubrutinib), and number of prior lines of therapy (1 vs ≥ 2). Eligible patients are adults aged ≥18 years with a confirmed diagnosis of MCL (cyclin D1 overexpression, and ≥ 1 B-cell marker) who have received ≥ 1 prior line of systemic therapy for MCL that did not include a prior BTKi. Patients must have measurable disease per Lugano criteria and must have progressed on or relapsed following the most recent line of therapy prior to study enrollment. Key exclusion criteria include a history of current or prior CNS involvement, significant cardiovascular disease, stroke, or intracranial hemorrhage within 6 months of randomization, and allogeneic stem cell transplant (SCT), autologous SCT or chimeric antigen receptor (CAR) T-cell therapy within 60 days of randomization. The primary endpoint is progression-free survival (PFS) per Lugano criteria assessed by an independent review committee (IRC), with the goal of demonstrating superiority of pirtobrutinib over investigator's choice of covalent BTKi. Secondary endpoints include overall response rate (ORR), duration of response (DoR), investigator-assessed PFS per Lugano criteria, overall survival (OS), event-free survival (EFS), time to treatment failure (TTF), time to next treatment (TTNT), time from randomization to disease progression on next line of treatment or death from any cause (PFS2), safety and tolerability, and patient reported outcomes. This global study is currently enrolling patients (NCT04662255). Disclosures Eyre: Gilead/KITE: Honoraria, Other: Travel support for conferences, Research Funding, Speakers Bureau; Janssen: Honoraria; Loxo Oncology: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Incyte: Consultancy; Abbvie: Consultancy, Honoraria, Other: Travel to conferences; Roche: Consultancy, Honoraria; AstraZeneca: Honoraria, Research Funding; Beigene: Honoraria, Research Funding; Secura Bio: Consultancy, Honoraria. Shah: Miltenyi Biotec: Consultancy, Honoraria, Research Funding; Kite: Consultancy; Epizyme: Consultancy; Umoja: Consultancy; Legend: Consultancy; Incyte: Consultancy; Lily: Consultancy, Honoraria, Research Funding. Dreyling: Novartis: Consultancy, Speakers Bureau; Janssen: Consultancy, Research Funding, Speakers Bureau; Roche: Consultancy, Research Funding, Speakers Bureau; Astra Zeneca: Consultancy, Speakers Bureau; BeiGene: Consultancy; Celgene: Consultancy, Research Funding, Speakers Bureau; Amgen: Speakers Bureau; Genmab: Consultancy; Bayer HealthCare Pharmaceuticals: Consultancy, Research Funding, Speakers Bureau; Gilead/Kite: Consultancy, Research Funding, Speakers Bureau; Abbvie: Research Funding; Incyte: Consultancy, Speakers Bureau. Vandenberghe: Jansnens: Honoraria; Abbvie: Honoraria. Jurczak: Abbvie, AstraZeneca, BeiGene, Celtrion, Celgene, Debbiopharm, Epizyme, Incyte, Janssen, Loxo Oncology, Merck, Mei Pharma, Morphosys, Novo Nordisk, Roche, Sandoz, Takeda, TG Therapeutics: Research Funding; Astra Zeneca, BeiGene, Janssen, Loxo Oncology, Sandoz, Roche,: Membership on an entity's Board of Directors or advisory committees. Wang: Genentech: Research Funding; Eli Lilly: Membership on an entity's Board of Directors or advisory committees; MorphoSys: Research Funding; LOXO Oncology: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding; InnoCare: Research Funding; Incyte: Membership on an entity's Board of Directors or advisory committees, Research Funding; TG Therapeutics: Membership on an entity's Board of Directors or advisory committees. Cheah: Loxo/Lilly: Consultancy, Honoraria, Other: advisory; Janssen: Consultancy, Honoraria, Other: advisory; Roche: Consultancy, Honoraria, Other: advisory and travel expenses, Research Funding; TG Therapeutics: Consultancy, Honoraria, Other: advisory; AstraZeneca: Consultancy, Honoraria, Other: advisory; Celgene: Research Funding; AbbVie: Research Funding; Beigene: Consultancy, Honoraria, Other: advisory; Ascentage pharma: Consultancy, Honoraria, Other: advisory; Gilead: Consultancy, Honoraria, Other: advisory; MSD: Consultancy, Honoraria, Other: advisory, Research Funding. Gandhi: Karyopharm Therapeutics: Honoraria; TG Therapeutics: Honoraria; GlaxoSmithKline: Honoraria. Sharman: AstraZeneca: Consultancy; Lilly: Consultancy; Pharmacyclics LLC, an AbbVie Company: Consultancy; Centessa: Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees; BeiGene: Consultancy; BMS: Consultancy; TG Therapeutics: Consultancy; AbbVie: Consultancy. Andorsky: Abbvie: Consultancy, Research Funding; Celgene/BMS: Consultancy, Research Funding; Epizyme: Research Funding. Yin: Loxo Oncology at Lilly: Current Employment; AstraZeneca: Ended employment in the past 24 months. Balbas: Nektar Therapeutics: Current equity holder in publicly-traded company, Ended employment in the past 24 months; Loxo Oncology at Lilly: Current Employment, Current equity holder in publicly-traded company. Kherani: Loxo Oncology at Lilly: Current Employment, Current equity holder in publicly-traded company. Wang: AstraZeneca, Bayer Healthcare, BeiGene, CSTone, DTRM Biopharma (Cayman) Limited, Epizyme, Genentech, InnoCare, Janssen, Juno, Kite Pharma, Loxo Oncology, Miltenyi Biomedicine GmbH, Oncternal, Pharmacyclics, VelosBio: Consultancy; Acerta Pharma, AstraZeneca, BeiGene, BioInvent, Celgene, Innocare, Janssen, Juno, Kite, Pharma, Lilly, Loxo Oncology, Molecular Templates, Oncternal, Pharmacyclics, VelosBio: Research Funding; Acerta Pharma, Anticancer Association, AstraZeneca, BeiGene, CAHON, Chinese Medical Association, Clinical Care Options, Dava Oncology, Epizyme, Hebei Cancer Prevention Federation, Imbruvica, Imedex, Janssen, Kite Pharma, Miltenyi Biomedicine GmbH, Moffit : Honoraria.

Cystic trophoblastic tumor (CTT) is a rare testicular germ cell tumor (GCT) predominantly seen in post-chemotherapy patients. It is prognostically similar to teratoma and requires no additional chemotherapy in the absence of a nonteratomatous GCT component. We report a case of metastatic CTT in a patient with primary testicular teratoma without prior chemotherapy. Retroperitoneal lymph node metastases contained teratoma, embryonal carcinoma, and CTT. The CTT was β-hCG positive and SALL4 negative by immunohistochemistry (IHC). CTT can arise in metastatic testicular GCT in treatment naïve patients. An important differential diagnosis is choriocarcinoma due to treatment implications, and SALL4 IHC may help.

Radiation fields for limited-stage nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) have shrunk over time; involved-site radiation therapy (ISRT) has replaced extended-field radiation therapy (EFRT) and involved-field radiation therapy (IFRT), but this has not been validated. The role of systemic therapy is unclear. We reviewed 71 stage I/II NLPHL patients and assessed progression-free survival (PFS), overall survival (OS), locoregional disease-free survival, and distant disease-free survival (DDFS). Median patient age was 39 years, and 61% had stage II disease. Thirty-six (51%) received radiation therapy (RT) only, 6 (8%) received systemic therapy only, and 29 (41%) received both. More patients receiving combined therapy had B symptoms (P = .035) and stage II disease (P = .001). In the RT-only group, 9 (25%) received EFRT, 13 (36%) received IFRT, and 14 (39%) received ISRT; in the combined-modality group, 3 (10%) received EFRT, 7 (24%) received IFRT, and 19 (66%) received ISRT. After a median follow-up of 6.2 years, 15 patients relapsed (13 distant, 2 locoregional). Five-year PFS and OS rates were 86% and 96% and did not differ by treatment. In the RT-only group, follow-up was shorter in the ISRT cohort (2.6 years vs 17.9 years [EFRT] and 8.5 years [IFRT], P < .01), but 5-year PFS did not differ by field size (P = .20). Locoregional control rates were 100% for the RT-only and combined groups, and corresponding 5-year DDFS rates were 93% and 95% (P = .95). Eight patients (11%) experienced a second malignancy (1 within RT field). Six patients died (1 from lymphoma). Use of limited ISRT fields does not appear to increase the risk of locoregional relapse, even when RT is given as single-modality therapy.

Importance Programmed cell death (PD-1) and programmed cell death ligand 1 (PD-L1) inhibitors have been increasingly used in cancer therapy. Understanding the treatment-related adverse events of these drugs is critical for clinical practice. Objective To evaluate the incidences of treatment-related adverse events of PD-1 and PD-L1 inhibitors and the differences between different drugs and cancer types. Data Sources PubMed, Web of Science, Embase, and Scopus were searched from October 1, 2017, through December 15, 2018. Study Selection Published clinical trials on single-agent PD-1 and PD-L1 inhibitors with tabulated data on treatment-related adverse events were included. Data Extraction and Synthesis Trial name, phase, cancer type, PD-1 and PD-L1 inhibitor used, dose escalation, dosing schedule, number of patients, number of all adverse events, and criteria for adverse event reporting data were extracted from each included study, and bayesian multilevel regression models were applied for data analysis. Main Outcomes and Measures Incidences of treatment-related adverse events and differences between different drugs and cancer types. Results This systematic review and meta-analysis included 125 clinical trials involving 20 128 patients; 12 277 (66.0%) of 18 610 patients from 106 studies developed at least 1 adverse event of any grade (severity), and 2627 (14.0%) of 18 715 patients from 110 studies developed at least 1 adverse event of grade 3 or higher severity. The most common all-grade adverse events were fatigue (18.26%; 95% CI, 16.49%-20.11%), pruritus (10.61%; 95% CI, 9.46%-11.83%), and diarrhea (9.47%; 95% CI, 8.43%-10.58%). The most common grade 3 or higher adverse events were fatigue (0.89%; 95% CI, 0.69%-1.14%), anemia (0.78%; 95% CI, 0.59%-1.02%), and aspartate aminotransferase increase (0.75%; 95% CI, 0.56%-0.99%). Hypothyroidism (6.07%; 95% CI, 5.35%-6.85%) and hyperthyroidism (2.82%; 95% CI, 2.40%-3.29%) were the most frequent all-grade endocrine immune-related adverse events. Nivolumab was associated with higher mean incidences of all-grade adverse events compared with pembrolizumab (odds ratio [OR], 1.28; 95% CI, 0.97-1.79) and grade 3 or higher adverse events (OR, 1.30; 95% CI, 0.89-2.00). PD-1 inhibitors were associated with a higher mean incidence of grade 3 or higher adverse events compared with PD-L1 inhibitors (OR, 1.58; 95% CI, 1.00-2.54). Conclusions and Relevance Different PD-1 and PD-L1 inhibitors appear to have varying treatment-related adverse events; a comprehensive summary of the incidences of treatment-related adverse events in clinical trials provides an important guide for clinicians.

Background The optimal initial therapy of follicular lymphoma (FL) remains unclear. The aims of this study were to compare primary treatment strategies and assess the impact of maintenance rituximab and patterns of treatment failure. Patients and methods We retrospectively analyzed patients with treatment-naive advanced stage, grade 1–2 FL treated at our center from 2004 to 2014. We included 356 patients treated on clinical trials or standard of care with rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone (R-CHOP, n = 119); R-CHOP with maintenance (R-CHOP + M, n = 65); bendamustine/rituximab (BR, n = 45); BR with maintenance (BR + M, n = 35); R2 (n = 94). We compared baseline characteristics, progression-free survival (PFS), overall survival (OS) and analyzed prognostic factors using univariate and multivariate analysis adjusted for treatment. Results After a median follow-up of 4 years (range 0.2–15.0), the 3-year PFS was 60% [95% confidence interval (CI) 51% to 69%] for R-CHOP, 72% (59% to 82%) for R-CHOP + M, 63% (42% to 78%) for BR, 97% (80% to 100%) for BR + M and 87% (78% to 93%) for R2. Patients treated with R-chemotherapy had more high-risk features than patients treated with R2 but, by adjusted multivariate analysis, treatment with R2 [hazard ratio (HR) 0.39 (0.17–0.89), P = 0.02] was associated with a superior PFS. Eastern Cooperative Oncology Group Performance status of one or more predicted inferior OS. Among patients treated with R-chemotherapy, maintenance was associated with the superior PFS [HR 0.38 (95% CI 0.21–0.68)]. By adjusted multivariate analysis, disease progression within 2 years [HR 5.1 (95% CI 1.57–16.83)] and histologic transformation (HT) [HR 11.05 (95% CI 2.84–42.93)] increased risk of death. Conclusion Induction therapy with R2 may result in disease control which is comparable with R-chemotherapy. Early disease progression and HT are predictive of inferior survival.

The last 5 years have seen significant advances in our understanding of the molecular pathogenesis of B-cell lymphomas. This has led to the emergence of a large number of new therapeutic agents exploiting precise aspects of the tumor cell's signaling pathways, surface antigens or microenvironment. The purpose of this comprehensive review is to provide a detailed analysis of the breakthrough agents in the field, with a focus on recent clinical data. We describe agents targeting the B-cell receptor pathway, Bcl-2 inhibitors, emerging epigenetic therapies, new monoclonal antibodies and antibody drug conjugates, selective inhibitors of nuclear export, agents targeting the programmed cell death axis and chimeric antigen receptor T cells.

Mantle cell lymphoma (MCL) is an uncommon subtype of non-Hodgkin lymphoma previously considered to have a poor prognosis. Large gains were made in the first decade of the new century when clinical trials established the importance of high-dose therapy and autologous stem-cell rescue and high-dose cytarabine in younger patients and the benefits of maintenance rituximab and bendamustine in older patients. In particular, greater depth of understanding of the molecular pathophysiology of MCL has resulted in an explosion of specifically targeted new efficacious agents. In particular, agents recently approved by the Food and Drug Administration include the proteasome inhibitor bortezomib, immunomodulator lenalidomide, and Bruton’s tyrosine kinase inhibitor ibrutinib. We review recent advances in the understanding of MCL biology and outline our recommended approach to therapy, including choice of chemoimmunotherapy, the role of stem-cell transplantation, and mechanism-based targeted therapies, on the basis of a synthesis of the data from published clinical trials.

Summary Background Ibrutinib is approved in the EU, USA, and other countries for patients with mantle cell lymphoma who received one previous therapy. In a previous phase 2 study with single-agent ibrutinib, the proportion of patients who achieved an objective response was 68%; 38 (34%) of 111 patients had transient lymphocytosis. We hypothesised that adding rituximab could target mantle cell lymphoma cells associated with redistribution lymphocytosis, leading to more potent antitumour activity. Methods Patients with a confirmed mantle cell lymphoma diagnosis (based on CD20-positive and cyclin D1-positive cells in tissue biopsy specimens), no upper limit on the number of previous treatments received, and an Eastern Cooperative Oncology Group performance status score of 2 or less were enrolled in this single-centre, open-label, phase 2 study. Patients received continuous oral ibrutinib (560 mg) daily until progessive disease or unacceptable toxic effects. Rituximab 375 mg/m 2 was given intravenously once per week for 4 weeks during cycle 1, then on day 1 of cycles 3–8, and thereafter once every other cycle up to 2 years. The primary endpoint was the proportion of patients who achieved an objective response in the intention-to-treat population and safety assessed in the as-treated population. The study is registered with ClinicalTrials.gov, number NCT01880567, and is still ongoing, but no longer accruing patients. Findings Between July 15, 2013, and June 30, 2014, 50 patients were enrolled. Median age was 67 years (range 45–86), and the median number of previous regimens was three (range 1–9). At a median follow-up of 16·5 months (IQR 12·09–19·28), 44 (88%, 95% CI 75·7–95·5) patients achieved an objective response, with 22 (44%, 30·0–58·7) patients achieving a complete response, and 22 (44%, 30·0–58·7) a partial response. The only grade 3 adverse event in >=10% of patients was atrial fibrillation, which was noted in six (12%) patients. Grade 4 diarrhoea and neutropenia occurred in one patient each. Adverse events led to discontinuation of therapy in five (10%) patients (atrial fibrillation in three [6%] patients, liver infection in one [2%], and bleeding in one [2%]). Two patients died while on-study from cardiac arrest and septic shock; the latter was deemed possibly related to treatment. Interpretation Ibrutinib combined with rituximab is active and well tolerated in patients with relapsed or refractory mantle cell lymphoma. Our results provide preliminary evidence for the activity of this combination in clinical practice. A phase 3 trial is warranted for more definitive data. Funding Pharmacyclics LLC, an AbbVie Company.

Context: Ibrutinib, a once-daily inhibitor of Bruton tyrosine kinase (BTK), is approved in the US for patients with MCL with ≥1 prior therapy. Single-agent ibrutinib received accelerated approval for MCL after showing complete response (CR) rates of 19–21% and overall response rates of 68–72% (Dreyling Lancet 2016; Wang NEJM 2013). Venetoclax is a BCL2 inhibitor approved in the US for patients with CLL with ≥1 prior therapy and for patients with previously untreated AML. Single-agent venetoclax has also shown efficacy in MCL, with CR rates of 21% (Davids J Clin Oncol 2017). In preclinical models, ibrutinib + venetoclax showed synergistic antitumor activity via dual inhibition of the BTK and BCL2 pathways (Zhao Br J Haematol 2015). In the phase 2 AIM study, 71% of 24 patients with MCL treated with ibrutinib + venetoclax had a best response of CR. Notably, the CR rate was 50% in patients with TP53 mutations, a population considered chemo-insensitive; this included 1 previously untreated patient (Tam NEJM 2018). Objective: To evaluate ibrutinib + venetoclax in patients ≥65 years and patients Design: This new open-label arm of the ongoing phase 3 SYMPATICO study will be conducted in ∼75 previously untreated patients with MCL. This study is currently enrolling patients. Patients or other participants: Key inclusion criteria include age ≥65 years or 18–65 years with a TP53 mutation, pathologically confirmed treatment-naive MCL with ECOG performance status of 0–2, and measurable disease. Patients with the blastoid variant of MCL, history of CNS lymphoma, or prior treatment with a BTK or BCL-2 inhibitor are ineligible. Interventions: Patients will receive oral, once daily 560 mg ibrutinib + venetoclax in a 5-week ramp-up to 400 mg venetoclax. Patients receive ibrutinib + venetoclax for 104 weeks; afterwards, venetoclax is discontinued in all patients and single-agent ibrutinib continues until progressive disease or unacceptable toxicity. Main outcome measures: The primary objective is to evaluate the CR rate. Secondary objectives include additional efficacy evaluations, safety, and pharmacokinetics. Funding: Pharmacyclics LLC, an AbbVie Company.

Importance Sex, age, and Eastern Cooperative Oncology Group (ECOG) performance status (PS) may affect immune response. However, the association of these factors with the survival benefit of cancer immunotherapy with immune checkpoint inhibitors (ICIs) remains unclear. Objective To assess the potential sex, age, and ECOG PS differences of immunotherapy survival benefit in patients with advanced cancer. Data Sources PubMed, Web of Science, Embase, and Scopus were searched from inception to August 31, 2019. Study Selection Published randomized clinical trials comparing overall survival (OS) in patients with advanced cancer treated with ICI immunotherapy vs non-ICI control therapy were included. Data Extraction and Synthesis Pooled OS hazard ratio (HR) and 95% CI for patients of different sex, age ( Main Outcomes and Measures The difference in survival benefit of ICIs between sex, age ( Results Thirty-seven phase 2 or 3 randomized clinical trials involving 23 760 patients were included. An OS benefit of immunotherapy was found for both men (HR, 0.75; 95% CI, 0.71-0.81) and women (HR, 0.79; 95% CI, 0.72-0.88); for both younger ( Conclusions and Relevance This meta-analysis found no evidence of an association of sex, age (

Introduction Outcomes with salvage regimens in pts with MCL who progress after Bruton tyrosine kinase inhibitor (BTKi) therapy are poor. ZUMA-2 is a Phase 2, registrational, multicenter study evaluating KTE-X19, an autologous anti-CD19 CAR T cell therapy, in pts with R/R MCL (1-5 therapies, including a BTKi). We present interim efficacy and safety results. Objectives Evaluate efficacy and safety of KTE-X19 in R/R MCL. Methods Eligible pts (≥ 18 y) with R/R MCL had an ECOG of 0-1 and ≤ 5 prior therapies, including chemotherapy, an anti-CD20 antibody, and a BTKi. Pts underwent leukapheresis and conditioning chemotherapy followed by KTE-X19 infusion at 2 × 106 cells/kg. Bridging therapy with dexamethasone, ibrutinib, or acalabrutinib was permitted. The primary endpoint was objective response rate (ORR; complete response [CR] + partial response) assessed by an Independent Review Committee per the Lugano Classification (Cheson, et al. J Clin Oncol. 2014). Interim efficacy endpoints were investigator-assessed using the revised IWG Response Criteria for Malignant Lymphoma (Cheson, et al. J Clin Oncol. 2007). Key secondary endpoints were duration of response (DOR), progression-free survival (PFS), overall survival (OS), frequency of adverse events (AEs), and blood levels of CAR T cells and cytokines. Sixty pts received KTE-X19; here, we present results in pts with ≥ 1 y follow-up. Updated results in all 60 pts will be reported in the presentation. Results As of May 30, 2018, 28 pts received KTE-X19 with ≥ 1 y follow-up (median, 13.2 mo). The median age was 65 y; 43% of pts had an ECOG score of 1; 21% had blastoid morphology; 82% had stage IV disease; 50% had intermediate/high-risk MIPI; and 86% received a median of 4 prior therapies. In 20 of 28 pts with available data, the median Ki-67 index was 38%. Eight pts received bridging therapy; all had disease present post-bridging. Investigator-assessed ORR was 86% (95% CI, 67-96) with a CR rate of 57% (95% CI, 37-76). As of May 30, 2018, 75% of responders remained in response, and 64% of treated pts had ongoing responses. The 12-month rates of DOR, PFS, and OS were 83% (95% CI, 60-93), 71% (95% CI, 50-84), and 86% (95% CI, 66-94), respectively; medians were not reached. The most common Grade ≥ 3 AEs were anemia (54%), platelet count decreased (39%), and neutropenia (36%). Grade 3/4 cytokine release syndrome (CRS) assessed by Lee et al. (Blood. 2014) and Grade 3/4 neurologic events (NE) occurred in 18% and 46% of pts, respectively, with no Grade 5 events. CRS and NE were generally reversible. There was 1 Grade 5 AE of organizing pneumonia. Median CAR T cell levels measured by peak and area under the curve were 99 cells/µL (range, 0.4-2589) and 1542 cells/µL (range, 5.5-27239), respectively. Conclusion With ≥ 1 y follow-up, KTE-X19 demonstrated significant and durable clinical benefit, with a manageable safety profile in pts with R/R MCL for whom there are no curative treatment options.

The BTK inhibitor ibrutinib has demonstrated a remarkable therapeutic effect in mantle cell lymphoma (MCL). However, approximately one-third of patients do not respond to the drug initially. To identify the mechanisms underlying primary ibrutinib resistance in MCL, we analyzed the transcriptome changes in ibrutinib-sensitive and ibrutinib-resistant cell lines on ibrutinib treatment. We found that MYC gene signature was suppressed by ibrutinib in sensitive but not resistant cell lines. We demonstrated that MYC gene was structurally abnormal and MYC protein was overexpressed in MCL cells. Further, MYC knockdown with RNA interference inhibited cell growth in ibrutinib-sensitive as well as ibrutinib-resistant cells. We explored the possibility of inhibiting MYC through HSP90 inhibition. The chaperon protein is overexpressed in both cell lines and primary MCL cells from the patients. We demonstrated that MYC is a bona fide client of HSP90 in the context of MCL by both immunoprecipitation and chemical precipitation. Furthermore, inhibition of HSP90 using PU-H71 induced apoptosis and caused cell cycle arrest. PU-H71 also demonstrates strong and relatively specific inhibition of the MYC transcriptional program compared with other oncogenic pathways. In a MCL patient-derived xenograft model, the HSP90 inhibitor retards tumor growth and prolongs survival. Last, we showed that PU-H71 induced apoptosis and downregulated MYC protein in MCL cells derived from patients who were clinically resistant to ibrutinib. In conclusion, MYC activity underlies intrinsic resistance to ibrutinib in MCL. As a client protein of HSP90, MYC can be inhibited via PU-H71 to overcome primary ibrutinib resistance.

The natural history of mantle cell lymphoma (MCL) is a continuous process with the vicious cycle of remission and recurrence. Because MCL cells are most vulnerable before their exposure to therapeutic agents, front-line therapy could eliminate MCL cells at the first strike, reduce the chance for secondary resistance, and cause long-term remissions. If optimized, it could become an alternative to cure MCL. The key is the intensity of front-line therapy. Both the Nordic 2 and the MD Anderson Cancer Center HCVAD trials, with follow-up times greater than 10 years, achieved long-term survivals exceeding 10 years. But the Achilles heel in both trials were the severe toxicities, such as secondary malignancies including myelodysplastic syndromes /leukemia. Therefore, intensive therapies can act as a double-edged sword providing long term survival at the cost of severe toxicities. In our opinion, although intensive chemotherapy can cause detrimental side effects, it is indispensable given that we run the risk of sacrificing long-term survivals in these young and fit patients. We must seek for a powerful alternative at the front-line. Furthermore, minimal residual disease negativity should be the optimal therapeutic goal to achieve before and after autologous stem cell transplantation. Some novel therapeutic strategies have shown to improve outcomes, but it is not yet clear as to how these results translate in population. Of note, MCL patients need to be stratified at diagnosis and be provided with different intensities of front-line regimen. In this review, we discuss current strategies for the treatment of young patients with newly diagnosed MCL.

Long term outcomes and mutations in patients with mantle cell lymphoma (MCL) who discontinued ibrutinib have not been described. Using deep targeted next generation sequencing, we performed somatic mutation profiling from 15 MCL patients (including 5 patients with paired samples; before and after progression on ibrutinib). We identified 80 patients with MCL who discontinued ibrutinib therapy for various reasons. Median follow-up after ibrutinib discontinuation was 38 months. The median duration on ibrutinib was 7·6 months. Forty-one (51%) patients discontinued ibrutinib due to disease progression/transformation, 20 (25%) for intolerance, 7 (9%) due to patient choice, 5 (6%) for stem cell transplant, 4 (5%) due to second cancers and 3 (4%) other causes. The median survival after ibrutinib was 10 and 6 months for disease progression and transformation, respectively, and 25 months for patients with ibrutinib intolerance. Overall, BTK mutations were observed in 17% patients after progression on ibrutinib. Notably, TP53 alterations were observed after progression in 75% patients. Among the 4 patients with blastoid transformation, 3 (75%) had NSD2 mutations (co-existing with TP53). Ibrutinib-refractory MCL patients had a short survival. Demonstration of TP53 and NSD2 mutations in patients who developed blastoid transformation and ATM and TP53 mutations in patients who progressed, opens the door for future investigations in ibrutinib-refractory MCL.

Background Hypereosinophilic syndrome (HEOS) is rare, and the efficacy of leukocytapheresis in this context is unclear. We here report the successful treatment of a patient with idiopathic HEOS with four leukocytapheresis procedures using two protocols. Case A 4-year-old female presented with cardiac and respiratory dysfunction, and WBC of 225 K/μL with 96% eosinophils. Leukocytapheresis was started after initiation of methylprednisolone and hydroxyurea. She received two leukocytapheresis with polymorphonuclear cell (PMN) protocol, followed by initiation of imatinib therapy, then two leukocytapheresis with mononuclear cell (MNC) protocol. After the fourth leukocytapheresis, her WBC decreased to 69 K/μL with 82% eosinophils. She was discharged on hospital day 21 under stable condition with WBC of 22 K/μL with 86% eosinophils. WBC count and eosinophil percentage continued to decrease, and were 6.4 K/μL and 52% by 2 weeks and 3.9 K/μL and 4.9% by 3 months after discharge, respectively. Findings WBC and absolute eosinophil (aEO) counts decreased by an average of 29.0 and 30.4% per leukocytapheresis, respectively. Normalized to estimated blood volume, procedures with PMN and MNC protocols changed, on average, WBC by −10.7 and −12.1%, aEO by −10.4 and −13.4%, platelet by −8.1 and −19.2%, and fluid balance by −129 and −47 mL, respectively. Conclusion Leukocytapheresis was effective in decreasing WBC and aEO counts in HEOS, with PMN and MNC protocols achieving similar reductions. However, PMN protocol resulted in greater negative fluid balance and MNC protocol resulted in greater platelet loss. J. Clin. Apheresis, 2015. © 2015 Wiley Periodicals, Inc.

Acute myeloid leukemia is a category of diseases with a common aggressive clinical presentation but with a prognosis and management that is dependent upon the underlying genetic characteristics of the neoplasm. The purpose of this brief review is to update the practicing pathologist on the current standard of care in the genetic evaluation of acute myeloid leukemia and to highlight future directions in the classification, genetic assessment, and management of these devastating diseases.

B cell receptor (BCR) signaling plays a key role in B cell development and function. Aberrant BCR signaling has been confirmed as a central driver for the pathogenesis of various B cell malignancies. Bruton's tyrosine kinase (BTK) is a vital component of BCR signaling and exhibits overexpression in various B cell leukemias and lymphomas. Inhibiting BTK has been proved as an efficient way for B cell malignancy intervention. Remarkable achievements have been made in the pursuit of selective BTK inhibitors, represented by the success of the irreversible BTK inhibitors, ibrutinib and acalabrutinib. Constantly emerging agents exhibiting superior efficacy and safety in preclinical and clinical studies provide promising therapeutics for the treatment of B cell malignancies.

Background Spontaneous regression has been reported in some indolent forms of lymphoma. Mantle cell lymphoma (MCL) is an aggressive lymphoid neoplasm and has a poor prognosis. However, approximately 30% of MCL patients can exhibit indolent clinical behavior. To date, complete spontaneous regression of MCL has not been reported. Case presentation We describe four cases of spontaneous regression of MCL. At the time of presentation, these patients were asymptomatic, with lymph node enlargement and mild to moderate fluorodeoxyglucose (FDG) uptake on FDG-positron emission tomography combined with computed tomography. One of the possible mechanisms of spontaneous regression of the tumor could be due to the host immune response through humoral and cellular immunity, which may have a role in the clearance of tumor cells. Conclusions In this report, we support the use of a “wait and watch” strategy for MCL patients with no risk factors and indolent behavior. This strategy helps spare patients from further potentially harmful chemotherapy. In addition, we describe the phenomenon of spontaneous regression in MCL patients who are asymptomatic and have low-volume disease.

Targeting of Akt has been validated as a well rationalized approach to cancer treatment, and represents a promising therapeutic strategy for aggressive hematologic malignancies. We describe herein an exploration of novel Akt inhibitors for cancer therapy through structural optimization of previously described 4-(piperazin-1-yl)-7 H -pyrrolo[2,3- d ]pyrimidine derivatives. Our studies yielded a novel series of pyrrolopyrimidine based phenylpiperidine carboxamides capable of potent inhibition of Akt1. Notably, 10h exhibited robust antiproliferative effects in both mantle cell lymphoma cell lines and primary patient tumor cells. Low micromolar doses of 10h induced cell apoptosis and cell cycle arrest in G 2 /M phase, and significantly downregulated the phosphorylation of Akt downstream effectors GSK3β and S6 in Jeko-1 cells.

Nodular lymphocyte Hodgkin lymphoma (NLPHL) is a rare disease for which the optimal therapy is unknown. We hypothesized that rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) could decrease rates of relapse and transformation. We retrospectively reviewed patients with NLPHL diagnosed between 1995 and 2015 confirmed by central pathologic review. Fifty-nine had sufficient treatment and follow-up data for analysis. We described progression-free survival (PFS), overall survival (OS), and histologic transformation according to treatment strategy and explored prognostic factors for PFS and OS. The median age at diagnosis was 41 years; 75% were male, and 61% had a typical growth pattern. Twenty-seven patients were treated with R-CHOP with an overall response rate of 100% (complete responses 89%). The median follow-up was 6.7 years, and the estimated 5- and 10-year PFS rates for patients treated with R-CHOP were 88.5% (95% confidence interval [CI], 68.4% to 96.1%) and 59.3 (95% CI, 25.3% to 89.1%), respectively. Excluding patients with histologic transformation at diagnosis, the 5-year cumulative incidence of histologic transformation was 2% (95% CI, 87% to 100%). No patient treated with R-CHOP experienced transformation. A high-risk score from the German Hodgkin Study Group was adversely prognostic for OS (P = .036), whereas male sex and splenic involvement were adversely prognostic for PFS (P = .006 and .002, respectively) but not OS. Our data support a potential role for R-CHOP in patients with NLPHL. Larger prospective trials are needed to define the optimal chemotherapy regimen.

Background: Outcomes with salvage regimens in pts with MCL who progress after Bruton tyrosine kinase inhibitor (BTKi) therapy are poor, with a median overall survival (OS) of 5.8 months (Martin, et al. Blood. 2016) and few pts proceeding to allogeneic stem cell transplant. ZUMA-2 is a Phase 2, registrational, multicenter, global study evaluating KTE-X19, an autologous anti-CD19 CAR T cell therapy, in pts with R/R MCL who received 1-5 prior therapies, including a BTKi. Here, we present interim efficacy and safety results from ZUMA-2. Methods: Eligible adults (aged ≥ 18 years) with R/R MCL had an ECOG score of 0 - 1 and ≤ 5 prior therapies, including chemotherapy, an anti-CD20 antibody, and a BTKi. Pts underwent leukapheresis and conditioning chemotherapy (cyclophosphamide 300 mg/m2/d and fludarabine 30 mg/m2/d for 3 days) followed by a single infusion of KTE-X19 at a target dose of 2 × 106 CAR T cells/kg. Pts could have received bridging therapy with dexamethasone, ibrutinib, or acalabrutinib after leukapheresis and before conditioning chemotherapy at the investigator's discretion. The primary endpoint was objective response rate (ORR [complete response (CR) + partial response]) assessed by an Independent Review Committee according to the Lugano Classification (Cheson, et al. J Clin Oncol. 2014). Interim efficacy endpoints were investigator-assessed using the revised IWG Response Criteria for Malignant Lymphoma (Cheson, et al. J Clin Oncol. 2007). Key secondary endpoints were duration of response (DOR), progression-free survival (PFS), OS, frequency of adverse events (AEs), levels of CAR T cells in blood, and levels of cytokines in serum. Efficacy and safety analyses included all pts who received KTE-X19. A total of 60 pts received KTE-X19; here, we present results in pts who had ≥ 1 year of follow-up. Updated safety and efficacy results in the full 60 pts, including pts who received revised AE management with the aim of decreasing toxicity, will be reported in the presentation. Results: As of May 30, 2018, 28 pts received KTE-X19 with ≥ 1 year of follow-up (median 13.2 months [range, 11.5 - 18.5]). The median age was 65 years (range, 50 - 75) and 86% of pts were male. Forty-three percent of pts had ECOG score of 1, 21% had blastoid morphology, 82% had stage IV disease, 50% had intermediate/high-risk MIPI, 86% received a median of 4 (range, 1 - 5) prior therapies, and 57% were refractory to last prior therapy. In 20/28 pts with available data, the median Ki-67 index was 38% (range, 5% - 80%). Eight pts received bridging therapy; all had disease present post-bridging. Investigator-assessed ORR was 86% (95% CI, 67% - 96%) with a CR rate of 57% (95% CI, 37% - 76%). As of May 30, 2018, 75% of responders remained in response and 64% of treated pts had ongoing responses. The 12-month estimates of DOR, PFS and OS were 83% (95% CI, 60% - 93%), 71% (95% CI, 50% - 84%), and 86% (95% CI, 66% - 94%), respectively and the medians were not reached. The most common Grade ≥ 3 AEs (≥ 20% of pts) were anemia (54%), platelet count decreased (39%), neutropenia (36%), neutrophil count decreased (32%), white blood cell count decreased (29%), encephalopathy (25%), and hypertension (21%). Grade 3/4 cytokine release syndrome (CRS) assessed by Lee et al. (Blood. 2014) was reported in 18% of pts, most commonly manifesting as hypotension (14%), hypoxia (14%), and pyrexia (11%). Grade 3/4 neurologic events (NE) were reported in 46% of pts and included encephalopathy (25%), confusional state (14%), and aphasia (11%). No Grade 5 CRS or NE occurred. All CRS events and most NE (15/17 pts) were reversible. Median time to onset and resolution of CRS was 2 days (range, 1 - 7) and 13 days (range, 4 - 60), respectively. Median time to onset of NE was 6 days (range, 1 - 15) and median time to resolution was 20 days (range, 9 - 99). There was 1 Grade 5 AE of organizing pneumonia that was considered related to conditioning chemotherapy. Median CAR T cell levels as measured by peak and area under the curve were 99 cells/µL (range, 0.4 - 2589) and 1542 cells/µL (range, 5.5 - 27239), respectively. Peak CAR T cell expansion was observed between Days 8 and 15 and declined over time. Conclusions: ZUMA-2 is the first multicenter Phase 2 study of CAR T cell therapy in pts with R/R MCL. With ≥ 1 year of follow-up, KTE-X19 demonstrated significant and durable clinical benefit, including a majority of pts achieving CR, and a manageable safety profile in pts with R/R MCL for whom there are no curative treatment options. Disclosures Wang: VelosBio: Research Funding; Guidepoint Global: Consultancy; BioInvent: Consultancy, Research Funding; Kite Pharma: Consultancy, Research Funding; Acerta Pharma: Consultancy, Research Funding; MoreHealth: Consultancy, Equity Ownership; AstraZeneca: Consultancy, Honoraria, Research Funding, Speakers Bureau; Pharmacyclics: Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding, Speakers Bureau; Loxo Oncology: Research Funding; Celgene: Honoraria, Research Funding; Juno Therapeutics: Research Funding; Aviara: Research Funding; Dava Oncology: Honoraria. Munoz:Pharmacyclics /Janssen: Consultancy, Research Funding, Speakers Bureau; Bayer: Consultancy, Speakers Bureau; Merck: Consultancy; Kyowa: Consultancy, Honoraria, Speakers Bureau; Seattle Genetics: Consultancy, Honoraria, Research Funding, Speakers Bureau; Celgene/Juno: Consultancy, Research Funding; Genentech: Consultancy, Research Funding, Speakers Bureau; Kite/Gilead: Consultancy, Research Funding, Speakers Bureau; Bristol-Myers Squibb: Consultancy; Alexion: Consultancy; Pfizer: Consultancy; Fosunkite: Speakers Bureau; AstraZeneca: Speakers Bureau; Portola: Research Funding; Incyte: Research Funding. Goy:Astrazenca: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; University of Nebraska: Research Funding; Hakensackumc: Research Funding; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Hackensack University Medical Center, RCCA: Employment; COTA: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Other: leadership role for profit healthcare company; Genentech: Other: Grants outside of the submitted work, Research Funding; Pharmacyclics/Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Grants outside of the submitted work, Research Funding; Kite, a Gilead Company: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Grants outside of the submitted work; Takeda: Other: Grants outside of the submitted work; Acerta: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Grants outside of the submitted work, Research Funding. Locke:Kite: Other: Scientific Advisor; Novartis: Other: Scientific Advisor; Cellular BioMedicine Group Inc.: Consultancy. Jacobson:Humanigen: Consultancy, Other: travel support; Novartis: Consultancy, Honoraria, Other: travel support; Bayer: Consultancy, Other: travel support; Precision Biosciences: Consultancy, Other: travel support; Kite, a Gilead Company: Consultancy, Honoraria, Other: travel support; Celgene: Consultancy, Other: travel support; Pfizer: Research Funding. Hill:Amgen: Research Funding; Pharmacyclics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Kite: Consultancy, Honoraria; Genentech: Consultancy, Research Funding; Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; TG therapeutics: Research Funding; Takeda: Research Funding; AstraZeneca: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria; Celegene: Consultancy, Honoraria, Research Funding. Timmerman:Spectrum Pharmaceuticals: Research Funding; Kite, A Gilead Company: Consultancy, Honoraria, Other: travel support, Research Funding; Merck: Research Funding; ImmunGene: Research Funding; Bristol-Myers Squibb: Consultancy, Honoraria, Other: travel support, Research Funding. Holmes:ADC Therapeutics: Research Funding; Kite, A Gilead Company: Consultancy, Speakers Bureau; Genentech: Research Funding; Janssen: Consultancy; Rigel: Consultancy, Speakers Bureau; Bayer: Consultancy; Novartis: Research Funding; Unum: Research Funding; Gilead: Consultancy; Juno: Consultancy; Seattle Genetics: Research Funding, Speakers Bureau. Jaglowski:Kite: Consultancy, Other: advisory board, Research Funding; Unum Therapeutics Inc.: Research Funding; Juno: Consultancy, Other: advisory board; Novartis: Consultancy, Other: advisory board, Research Funding. Flinn:TG Therapeutics, Trillum Therapeutics, Abbvie, ArQule, BeiGene, Curis, FORMA Therapeutics, Forty Seven, Merck, Pfizer, Takeda, Teva, Verastem, Gilead Sciences, Astra Zeneca (AZ), Juno Therapeutics, UnumTherapeutics, MorphoSys, AG: Research Funding; Acerta Pharma, Agios, Calithera Biosciences, Celgene, Constellation Pharmaceuticals, Genentech, Gilead Sciences, Incyte, Infinity Pharmaceuticals, Janssen, Karyopharm Therapeutics, Kite Pharma, Novartis, Pharmacyclics, Portola Pharmaceuticals: Research Funding; AbbVie, Seattle Genetics, TG Therapeutics, Verastem: Consultancy; TG Therapeutics, Trillum Therapeutics, Abbvie, ArQule, BeiGene, Curis, FORMA Therapeutics, Forty Seven, Merck, Pfizer, Takeda, Teva, Verastem, Gilead Sciences, Astra Zeneca (AZ), Juno Therapeutics, UnumTherapeutics, MorphoSys, AG: Research Funding; F. Hoffmann-La Roche Ltd: Research Funding. McSweeney:Fred Hutchinson Cancer Research Center: Patents & Royalties; Colorado Blood Cancer Institute Medical Group: Employment; Kite, a Gilead Company: Consultancy, Honoraria, Research Funding, Speakers Bureau. Miklos:AlloGene: Consultancy; Janssen: Consultancy; Pharmacyclics: Consultancy, Patents & Royalties, Research Funding; Kite, A Gilead Company: Consultancy, Research Funding; Celgene-Juno: Consultancy; Novartis: Consultancy; Miltenyi: Consultancy, Research Funding; Adaptive Biotechnologies: Consultancy, Research Funding; Becton Dickinson: Consultancy; Precision Bioscience: Consultancy. Pagel:Gilead Sciences: Consultancy; Pharmacyclics: Consultancy; AstraZeneca: Consultancy. Kersten:Amgen: Other: Travel grants, honorarium, or advisory boards; Roche: Other: Travel grants, honorarium, or advisory boards; Janssen/Cilag: Other: Travel grants, honorarium, or advisory boards; Roche: Consultancy, Research Funding, Travel grants, honorarium, or advisory boards; Celgene: Other: Travel grants, honorarium, or advisory boards; Celgene: Consultancy, Research Funding; Bristol Myers Squibb: Other: Travel grants, honorarium, or advisory boards; MSD: Other: Travel grants, honorarium, or advisory boards; Takeda: Consultancy, Research Funding; Gilead: Other: Travel grants, honorarium, or advisory boards; Kite: Consultancy, Other: Travel grants, honorarium, or advisory boards; Novartis: Consultancy, Other: Travel grants, honorarium, or advisory boards. Peng:Kite, A Gilead Company: Employment. Rossi:Kite, A Gilead Company: Employment. Jain:Vida Ventures: Employment; Kite, A Gilead Company: Employment, Equity Ownership, Other: Travel support; Amgen: Equity Ownership. Rao:Kite, A Gilead Company: Employment. Reagan:Kite, A Gilead Company: Consultancy; Curis: Consultancy; Seattle Genetics: Research Funding. OffLabel Disclosure: ZUMA-2 is a clinical trial evaluating KTE-X19, an investigational CAR T cell therapy

Introduction. The combination of rituximab and lenalidomide (R2) is active in patients with untreated indolent lymphoma. Recent randomized trials (RELEVANCE) have demonstrated similar efficacy when compared to standard chemo-immunotherapy backbones. Long term follow up of patients receiving R2 as well as predictors of long term remission and survival have yet to be published. Methods. We prospectively evaluated patients with low grade advanced stage FL who received R2 as initial treatment at our institution between 07/2008 and 10/2014. Lenalidomide was given at 20 mg (day 1-21, in a 28 day cycle) for 6 cycles with rituximab monthly. Lenalidomide starting dose was 10 mg if baseline creatinine clearance was < 60 mL/min. Patients with an objective response continued with 10-20 mg of lenalidomide with rituximab for up to 12 more cycles. Response was evaluated according to 2014 Lugano criteria. Results. One-hundred and one patients were included in the analysis, baseline characteristics are shown in the Table. Median number of provided cycles was 7 (range, 1-20). Median dose of lenalidomide was 20 mg (range, 5-20 mg), and 29 (29%) patients required a dose reduction. Fifty-six (55%) patients experienced grade 3-4 treatment-related toxicities, the most common (> 5%) being neutropenia (39%), skin rash (20%), myalgia (16%) and fatigue (16%). Seven (7%) patients discontinued treatment before completion, after a median time of 4 months (range, 1-10 months): 4 because of toxicity (arterial thrombosis in 2, respiratory failure in 1, and skin rash in 1), and 3 because of progression. Ninety-eight patients were evaluable for response, while 3 patients discontinued treatment because of toxicity before first response assessment. Overall response rate was 98%, CR rate 90% (both achieved after a median of 6 months [range, 3-22 months]), and CR rate at 30 months (CR30) was 80%. Only female sex associated with a higher CR rate (96% vs 83%, p=0.05), while no baseline characteristic associated with CR30 rate. After a median follow-up of 88 months (95% confidence interval, 84-92 months), 31 (31%) patients progressed and/or died, 7-year progression-free survival (PFS) was 63%, and 13% of patients had a PFS < 24 months (PFS24). Failure to achieve CR was the only factor associated with significantly decreased PFS (10 months vs not reached, p At most recent follow-up, transformation was reported in 3 (3%) patients, after 30, 32 and 42 months, respectively. Two (2%) patients have died, 1 of unrelated comorbid health conditions, 1 of progressive disease, and 7-year overall survival was 98%. Second cancers (excluding transformation) were diagnosed in 8 (8%) patients, after a median of 55 months (range, 3-105 months). These included: breast adenocarcinoma (2), melanoma (2), pancreatic adenocarcinoma (1), esophageal adenocarcinoma (1), and therapy-related acute myeloid leukemia. Discussion. Long-term follow-up show very favorable outcomes for patients with advanced stage FL receiving R2 as initial treatment, independent of traditional prognostic factors relevant to patients treated with chemoimmunotherapy, including FLIPI and FLIPI-2 score. Combination strategies, aimed at increasing depth of response to R2, may further improve outcomes observed with this regimen. Table. Disclosures Nastoupil: Bayer: Honoraria; Genentech, Inc.: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Gilead: Honoraria; Janssen: Honoraria, Research Funding; Novartis: Honoraria; TG Therapeutics: Honoraria, Research Funding; Spectrum: Honoraria. Westin:Janssen: Other: Advisory Board, Research Funding; Unum: Research Funding; Curis: Other: Advisory Board, Research Funding; 47 Inc: Research Funding; Genentech: Other: Advisory Board, Research Funding; Juno: Other: Advisory Board; Celgene: Other: Advisory Board, Research Funding; MorphoSys: Other: Advisory Board; Novartis: Other: Advisory Board, Research Funding; Kite: Other: Advisory Board, Research Funding. Wang:AstraZeneca: Consultancy, Honoraria, Research Funding, Speakers Bureau; MoreHealth: Consultancy, Equity Ownership; Acerta Pharma: Consultancy, Research Funding; BioInvent: Consultancy, Research Funding; Pharmacyclics: Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding, Speakers Bureau; Juno Therapeutics: Research Funding; Dava Oncology: Honoraria; Celgene: Honoraria, Research Funding; Aviara: Research Funding; Kite Pharma: Consultancy, Research Funding; Guidepoint Global: Consultancy; VelosBio: Research Funding; Loxo Oncology: Research Funding. Neelapu:Pfizer: Consultancy; Precision Biosciences: Consultancy; Merck: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Allogene: Consultancy; Novartis: Consultancy; BMS: Research Funding; Kite, a Gilead Company: Consultancy, Research Funding; Cellectis: Research Funding; Acerta: Research Funding; Karus: Research Funding; Poseida: Research Funding; Incyte: Consultancy; Cell Medica: Consultancy; Unum Therapeutics: Consultancy, Research Funding. Fowler:Roche: Membership on an entity's Board of Directors or advisory committees, Research Funding; ABBVIE: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis Pharmaceuticals Corporation: Consultancy; TG Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding. OffLabel Disclosure: lenalidomide and rituximab are not yet FDA-approved as frontline treatment for patients with FL

Background: Mantle cell lymphoma (MCL), which accounts for around 7% of non-Hodgkin lymphomas, is currently incurable. MCL's key survival pathway is the B-cell receptor pathway, and Bruton's tyrosine kinase (BTK), the critical component of this pathway, is fundamentally activated in MCL. Ibrutinib, an agent that inhibits BTK, produced a 68% clinical response rate in patients with relapsed/refractory MCL, leading to its FDA approval. However, if MCL patients experience relapse following ibrutinib therapy or do not respond to ibrutinib, the 1-year survival rate is only 22%. Therefore, determining the mechanisms underlying ibrutinib resistance and identifying alternative therapeutic options are urgent unmet needs. Our group and others have shown that the BTK mutation associated with ibrutinib resistance is rare in MCL, and targeting alternative survival pathways to overcome ibrutinib resistance has not shown promising results. Methods: To explore novel biomarkers or therapeutic targets, we performed whole exome and transcriptome sequencing and RNA-seq of ibrutinib-treated clinical specimens. Patient primary cells were isolated from MCL patients treated with ibrutinib either prior to treatment or at treatment discontinuation. Whole exome sequencing (WES) was performed to determine the mutational landscape of ibrutinib resistance. RNA-seq was employed to compare the gene expression profiles between ibrutinib-sensitive and -resistant patient samples. Gene set enrichment analysis was utilized to identify dysregulated molecular pathways associated with the resistant phenotype. The RNA-seq data were then validated with western blots. Functional studies targeting this molecular pathway were conducted, and in vivo efficacy was investigated in the ibrutinib-resistant MCL patient-derived xenograft (PDX) mouse model. Results: Co-deletion of CDKN2A and MTAP was frequently detected in ibrutinib-resistant tumors but not in ibrutinib-sensitive tumors. We also found that metabolic reprogramming towards oxidative phosphorylation (OXPHOS) potentially drives ibrutinib resistance. IACS-010759, a small molecule developed by MD Anderson Cancer Center, inhibits OXPHOS and overcomes ibrutinib resistance in vitro and in PDX models. Nevertheless, the potential drivers of this observed metabolic reprogramming towards OXPHOS remain unclear. MTAP encodes 5-methylthioadenosine phosphorylase, a critical enzyme in the methionine salvage pathway, and is frequently lost in cancer cells, resulting in accumulation of metabolite methylthioadenosine and overexpression of protein arginine methyltransferase 5 (PRMT5). Thus, PRMT5 is a potential druggable therapeutic target to overcome ibrutinib resistance in MCL. We found that PRMT5 is highly expressed in ibrutinib-resistant MCL but not ibrutinib-sensitive MCL (7 ibrutinib-resistant vs. 15 ibrutinib-sensitive patient samples, p = 0.0051), especially in MTAP-deleted MCL specimens. Furthermore, patients with high PRMT5 levels had poor clinical outcomes on ibrutinib treatment. PRMT5 regulates tumor survival pathways by the methylation of histones H3R8, H4R3, and post-translational methylation of non-histone proteins, including p53, E2F1, BCL6, p65, and others. A novel PRMT5 inhibitor, GSK3226595, significantly inhibited tumor growth in an ibrutinib-resistant MCL PDX model (n = 5; vehicle vs. GSK3226595, p = 0.000048) and had no significant mouse body weight change (GSK3226595 vs. vehicle, p = 0.08). Conclusion: This study may pave the way to develop a PRMT5/OXPHOS-based therapeutic strategy to overcome ibrutinib resistance in MCL. Disclosures Wang: Juno Therapeutics: Research Funding; Aviara: Research Funding; Dava Oncology: Honoraria; Celgene: Honoraria, Research Funding; Loxo Oncology: Research Funding; VelosBio: Research Funding; Janssen: Consultancy, Honoraria, Research Funding, Speakers Bureau; Pharmacyclics: Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria, Research Funding, Speakers Bureau; MoreHealth: Consultancy, Equity Ownership; Acerta Pharma: Consultancy, Research Funding; Kite Pharma: Consultancy, Research Funding; Guidepoint Global: Consultancy; BioInvent: Consultancy, Research Funding.

Introduction: FL, the most common indolent non-Hodgkin lymphoma, is characterized by a defective immune microenvironment that suppresses normal T-cell and natural-killer (NK)-cell activity. The clinical course is often depicted by high initial response rates coupled with a prolonged natural history and repeated relapses with most patients (pts) succumbing to their disease. Effective, well tolerated therapies are desirable. Obinutuzumab (O) is a humanized, type II anti-CD20 monoclonal antibody glycoengineered for enhanced antibody-dependent cellular cytotoxicity (ADCC). Lenalidomide (len) is an immunomodulatory agent that binds the cereblon E3 ubiquitin ligase complex resulting in recruitment, ubiquitination, and degradation of transcription factors Aiolos and Ikaros resulting in T-cell and NK-cell activation. Therefore, combining O with len is anticipated to be synergistic in augmenting the innate and adaptive immune response in FL. The combination has been shown to be well tolerated and effective in relapsed FL (Fowler ICML 2017). Therefore, we sought to explore the efficacy and safety of O-len in previously untreated, high tumor burden FL. Methods: We conducted as single-center, phase 2 study in previously untreated, stage II, III, or IV, high tumor burden (defined by GELF) FL (grade 1, 2 or 3A). Pts received 1000mg of O on days 1, 8, and 15 of cycle 1, day 1 of cycles 2-6, and day 1 of even numbered cycles, cycle 8-30. Cycle length was 28 days. Len was administered as 20mg on days 1-21 of cycles 1-6. Pts in a complete response (CR) after 6 cycles received reduced dose len (10mg on days 1-21) for cycles 7-18. Among pts in a partial response (PR) after 6 cycles, len was continued at 20mg for the next 3-6 cycles or until CR, whichever occurred first, len was then dose reduced to 10mg on days 1-21 for the remainder of 18 cycles. The primary endpoint was progression-free survival (PFS) at 2 years (according to Lugano 2014 criteria). Secondary endpoints included: safety, CR, PR, overall response (ORR), and overall survival (OS). Results: 90 pts with high tumor burden FL were enrolled. Median age was 58 years (range 33-84), 52% (N=47) were male, 67 (74%) had an ECOG performance status of 0, 9 (10%) had stage II, 23 (26%) stage III, and 58 (64%) had stage IV disease. The majority had grade 1/2 FL (80%). Twenty-one percent had low risk FLIPI scores, 37% intermediate risk, and 42% were high risk. With a median follow-up of 22 months (range 1-30 months), the 2-year PFS estimate is 96% (95% CI 92-100%) with only 2 pts experiencing progression to date. The ORR is 98% (85 CR, 1 PR), 92% achieved a CR at the first response assessment (cycle 4, day 1). Correlative studies are underway including serial circulating tumor DNA measurements. No deaths have been observed to date. Eleven pts (12%) discontinued therapy as a result of an adverse event (AE), upper respiratory infection was the most common reason (N=5). Other reasons included bradycardia with sick sinus syndrome, urinary tract infection, constipation, abdominal pain, fatigue, foot neuroma (N=1 for each instance). The most common grade 3 or higher AEs include neutropenia (16%, grade 3 N=5, grade 4 N= 9), rash (10%), lung infection (4%), neutropenic fever (1%). Conclusions: O-Len was associated with very high CR rates and 2-year PFS estimates in untreated, high tumor burden FL. The toxicity profile was manageable. Further study of this effective, immune therapy approach in untreated FL is warranted. Figure Disclosures Nastoupil: Bayer: Honoraria; Celgene: Honoraria, Research Funding; Genentech, Inc.: Honoraria, Research Funding; Gilead: Honoraria; Janssen: Honoraria, Research Funding; Novartis: Honoraria; TG Therapeutics: Honoraria, Research Funding; Spectrum: Honoraria. Westin:Genentech: Other: Advisory Board, Research Funding; Unum: Research Funding; Novartis: Other: Advisory Board, Research Funding; Janssen: Other: Advisory Board, Research Funding; Juno: Other: Advisory Board; 47 Inc: Research Funding; MorphoSys: Other: Advisory Board; Kite: Other: Advisory Board, Research Funding; Curis: Other: Advisory Board, Research Funding; Celgene: Other: Advisory Board, Research Funding. Parmar:Cellenkos Inc.: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Research Funding. Wang:Pharmacyclics: Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria, Research Funding, Speakers Bureau; Acerta Pharma: Consultancy, Research Funding; Janssen: Consultancy, Honoraria, Research Funding, Speakers Bureau; MoreHealth: Consultancy, Equity Ownership; Kite Pharma: Consultancy, Research Funding; Guidepoint Global: Consultancy; BioInvent: Consultancy, Research Funding; VelosBio: Research Funding; Loxo Oncology: Research Funding; Celgene: Honoraria, Research Funding; Juno Therapeutics: Research Funding; Aviara: Research Funding; Dava Oncology: Honoraria. Neelapu:Acerta: Research Funding; Celgene: Consultancy, Research Funding; Kite, a Gilead Company: Consultancy, Research Funding; Allogene: Consultancy; Cell Medica: Consultancy; Unum Therapeutics: Consultancy, Research Funding; Pfizer: Consultancy; Poseida: Research Funding; Karus: Research Funding; Novartis: Consultancy; Incyte: Consultancy; BMS: Research Funding; Cellectis: Research Funding; Precision Biosciences: Consultancy; Merck: Consultancy, Research Funding. Fowler:ABBVIE: Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Membership on an entity's Board of Directors or advisory committees, Research Funding; TG Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis Pharmaceuticals Corporation: Consultancy. OffLabel Disclosure: Lenalidomide in untreated follicular lymphoma

Introduction: Mantle cell lymphoma is an aggressive subtype of non-Hodgkin lymphoma with poor prognosis. MCL cells display complex inter- and intra-patient heterogeneity and various dissemination patterns involving nodal and extranodal sites across patients. Due to its microenvironment distinct from patients' microenvironments, heterotopic or subcutaneous patient-derived xenograft (PDX) models are not ideal for studying clinical disease pathology, tumor heterogeneity, and clinical therapeutic responses. In contrast, patient-derived orthotopic xenografts (PDOXs) have been shown in many cancer types to faithfully recapitulate the primary patient cancers. Although a few MCL PDOX models have reportedly been established, these models have not been clearly defined or applied in mechanistic studies or preclinical drug studies. Methods: We established multiple MCL PDOX models from primary patient samples via intravenous or intraosseous routes and characterized these models for the first time in multiple dimensions. We performed longitudinal pathological and histological characterization of PDOX cells involved in the spleen, liver, stomach, lymph nodes, bone marrow, and/or peripheral blood across generations and disease stages, whole exon sequencing across dissemination sites and generations, and single-cell RNA sequencing across dissemination sites. We evaluated in vivo response to ibrutinib and venetoclax in one PDOX model derived from an ibrutinib-venetoclax dual-resistant MCL patient. An in vivo drug efficacy screen was performed to search for potential therapies to overcome ibrutinib-venetoclax dual resistance. Results: Longitudinal pathological and histological characterization of the PDOX models revealed faithful recapitulation of the clinical disease of MCL patients, and the PDOX models can be stably passed on to a series of generations. In vivo drug treatments including ibrutinib and venetoclax recapitulated the clinical response to these therapies. Whole exon sequencing and single-cell RNA sequencing of one ibrutinib-venetoclax dual-resistant PDOX model and its parental primary patient cells reflected reliable recapitulation of primary patient disease in genetic, cellular, and transcriptomic profiles, providing insights into potential targets to overcome therapeutic resistance. Single-cell transcriptomic profiling also revealed increased cancer hallmark signaling in the PDOX model compared to the primary patient samples used to established the PDOX model. Based on this, we performed an in vivo drug screen for the PDOX model and identified promising drugs that dramatically inhibited tumor burden in the spleen, liver, bone marrow, and peripheral blood. Intriguingly, a subcutaneous model (scPDOX) was derived from this PDOX model via subcutaneous implantation of its G1 PDOX cells and was found to be ibrutinib-resistant but venetoclax-sensitive in vivo. To understand the differential response to venetoclax and differential microenvironment of the PDOX model and its derived scPDOX model, whole exon sequencing and single-cell RNA sequencing of the cells from these models is currently being pursued. Conclusions: Our MCL PDOX models faithfully resembled the original MCL disease in histopathology, disease progression, tumor heterogeneity, genetic-transcriptomic profiling, and therapeutic responses. Therefore, these models provide invaluable platforms for mechanistic studies and preclinical drug studies. Disclosures Wang: VelosBio: Research Funding; Guidepoint Global: Consultancy; BioInvent: Consultancy, Research Funding; Juno Therapeutics: Research Funding; Aviara: Research Funding; Dava Oncology: Honoraria; Kite Pharma: Consultancy, Research Funding; Acerta Pharma: Consultancy, Research Funding; MoreHealth: Consultancy, Equity Ownership; AstraZeneca: Consultancy, Honoraria, Research Funding, Speakers Bureau; Pharmacyclics: Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding, Speakers Bureau; Loxo Oncology: Research Funding; Celgene: Honoraria, Research Funding.