Seshan, Venkatraman

Background: Disseminated marginal zone lymphoma (MZL) is an indolent disease often observable at diagnosis with treatment indications similar to other indolent lymphomas. First-line therapy is typically rituximab alone or in combination with chemotherapy (e.g. bendamustine). Due to the long-life expectancy, avoiding alkylating agents to reduce bone marrow damage could be beneficial. In addition, a “chemotherapy free” option could have fewer and less severe complications. Bruton tyrosine kinase inhibitors (BTKi) are active and approved or NCCN-recommended beyond first line therapy in MZL. Moreover, BTKi are approved for first line therapy in Waldenstrom's Macroglobulinemia, a disease with both diagnostic and pathophysiologic overlap with MZL. We conducted a multicenter randomized trial of rituximab induction plus ibrutinib/placebo (RI vs RP) for patients with MZL in need of first line systemic therapy. Complete response (CR) rate at 30 months was the primary endpoint and progression free survival (PFS) was secondary. The target sample size was 63 in each arm. The study was closed after 22 eligible patients enrolled due to low accrual. Methods: Patients (pts) with either nodal, splenic or extranodal MZL were eligible. Prior surgery, radiation, antibiotic or antiviral therapy for MZL were allowed if followed by disease progression requiring treatment. Documented evidence of need for treatment included, but was not limited to, threatened end-organ function, bulky disease (>5 cm), symptoms, requirement for transfusion or growth factor support, or significant need for intervention. Transformation to DLBCL was excluded prior to entry including bone marrow assessment. Randomization occurred prior to rituximab weekly x 4 to either daily placebo (RP) or ibrutinib (RI) 560 mg starting on day 1 and continued until disease progression (PD), intolerance or CR at 30 months. Those with partial response (PR) or stable disease (SD) at 30 months could continue placebo or ibrutinib. CR assessment required both a negative FDG-PET and bone marrow biopsy. RESULTS: 22 pts enrolled (Feb 2020-March 2023) with baseline characteristics including: median age 67 years (35-78) and White race 17. Stage II (3), III/IV (17). Subtype: splenic 16, nodal 4, extranodal 2. Prior therapy: splenectomy 1, radiation 0, other surgery 0, antiviral/antibiotic 0. Median maximal tumor dimension was 3.7 cm (range 1.6-23.6); with >5 cm in 9 pts. Median time from diagnosis to treatment was 32 days (5-4712 with only 3 > 1 year). 11 pts were randomized to each arm. Responses: RP: 3 CR, 4 PR, 3 SD, 1 inevaluable; RI: 7 CR, 4 PR. No patient achieved CR30, but 3 had CR at 29 months: 2 RP, 1 RI. With a median follow up of 35 months (13-50), the median PFS by Log Rank was 14 mo (RP) vs 29 (RI), though this difference was not statistically significant in the setting of small numbers. Treatment was well tolerated. Only 1 pt experienced grade 3 events at least possibly related: hypoxia and dyspnea. This was attributed to COVID-19 and occurred on the RP arm. 1 CR patient with baseline clonal hematopoiesis developed myelodysplasia. Treatment improved baseline activities in 4/5 pts (1 RP, 3 RI). Baseline pain improved in 8 pt: 4 RP, 4 RI. All pts were alive at the data cuff off. Conclusions: This study is a chemotherapy free frontline trial in MZL and the first to utilize ibrutinib in frontline MZL. All pts received rituximab induction and were randomized at entry to RP vs RI. The COVID-19 pandemic affected site activation and accrual, ultimately contributing to low accrual and early study termination. Nonetheless, the results suggest a marked difference in median PFS favoring the RI arm, although small numbers preclude a statistically significant result. Notably, our results are qualitatively similar to those of Dimopoulos (NEJM, 2018) in Waldenstrom's Macroglobulinemia, a disease with similar characteristics to MZL. In that study, the median PFS by Log Rank was 20 months (RP) vs not reached (RI); and 30-month PFS 28% (RP) vs 82% (RI). (Hazard ratio for progression or death, 0.20; P<0.001). Further, our trial supports pursing a chemotherapy free first line approach in MZL.

Multiple CD19-directed therapies are available for the treatment of relapsed and refractory (R/R) DLBCL, including CAR T cells, tafasitamab/lenalidomide (TL), and loncastuximab tesirine (lonca-T) (Sermer D., Blood Rev 2023). However, there are few data available on the efficacy of sequential CD19-directed therapies. We performed a retrospective study evaluating all patients with R/R LBCL treated consecutively with TL at 11 institutions from 8/2020 to 8/2022, identifying 178 patients. In this study, we specifically evaluate outcomes in patients who received anti-CD19 therapy prior to or after TL. The primary outcome of interest was progression-free survival (PFS) in TL recipients who previously received CD19-directed CAR T therapy, with overall response rate (ORR), complete response rate (CRR), and overall survival (OS) also evaluated. Outcomes of lonca-T and CAR T after TL therapy were evaluated. Data on CD19 expression was assessed on biopsies after TL; this was determined locally using flow cytometry or immunohistochemistry per institutional protocols. In subgroup analyses, ORR and CRR were compared using Fisher's exact test. PFS and OS were estimated using the Kaplan-Meier method, with differences tested using the log-rank test. Of 178 patients who received TL, 52 had received prior anti-CD19 CAR T therapy, at a median of 7.4 months before TL (Table 1). Median PFS was lower in prior CAR T recipients (1.6 mo, 95% CI 1.1-2.5) vs no prior CAR T (2.1 mo, 95% CI 1.8-3.2), with hazard ratio 1.46 (p = 0.04; Figure 1). Best ORR was lower in patients with prior CAR T exposure (15% vs 33%, p = 0.02) though CRR was not significantly different (15% vs 18%, p = 1.0). We specifically evaluated TL outcomes based on prior response to CAR T, given the previously identified association of refractory disease with poor TL outcomes (Qualls D et al., presented at ASH 2022). Of 19 patients who had progressive disease more than 6 months after CAR T, ORR and CRR to TL therapy were 31.6% (all responses were CRs); in 33 patients with refractory disease (less than CR or relapse within 6 months) after CAR T, ORR and CRR to TL were significantly lower, at 6.1% (p = 0.04). Median PFS after TL was shorter in CAR-refractory than CAR-relapsed disease, at 1.4 vs 3.5 months (HR 2.2, p = 0.02). Of 88 patients who received therapy after TL, 20 (23%) received lonca-T and 14 (16%) received CAR T. Data on survival and initiation of new treatment after CAR T or lonca-T was available, but response and progression data after CAR T or lonca-T therapy is pending. These data allowed an estimate of OS and event-free survival (EFS), defined as survival without initiation of a new treatment after CAR T or lonca-T. With a median 3.9 months' follow-up, median EFS after CAR T administration was 3.7 months (95% CI, 0.9 - 6.5), and median OS was 8.1 months (95% CI, 0.6 - 15.7). In patients who received lonca-T, with median 2.7 months' follow-up from initiation, median EFS was 2.8 months (95% CI, 0.9 - 4.7), and median OS was 3.5 months (95% CI, 1.2 - 5.7). When comparing CAR T and lonca-T to polatuzumab vedotin- or chemotherapy-based therapies after TL, there were no significant differences in OS or EFS. In patients who discontinued TL, 24 had a biopsy a median of 18 days after the last dose of tafasitamab. Of these, 13 (54%) were CD19-positive and 11 (46%) were CD19-negative. All samples obtained more than 21 days after tafasitamab (6/6) were CD19-positive, while 46% obtained within 21 days were CD19-positive. These time-dependent findings may reflect “epitope masking” by tafasitamab rather than CD19 loss, reflecting other recent reports (Fitzgerald K., Leuk Lym 2022; Duell J., Leuk Lym 2022). In patients receiving TL after CAR T, responses and PFS were lower than in patients without prior CAR T therapy; however, with disease that was not refractory to prior CAR T, results were similar to patients who had not had prior CAR T. This may reflect that refractory disease, regardless of prior therapy, is associated with shorter PFS, though the possibility of CD19-mediated mechanisms of resistance remains. Modest EFS and OS were seen in patients receiving CAR T therapy or lonca-T after already receiving TL, though this may also reflect the high-risk disease characteristics of this cohort. Overall, in a high-risk, real-world cohort of TL-treated patients, these data suggest that some patients may benefit from subsequent CD19-directed therapies, but better therapeutic options are needed.

Abstract In this real-world evaluation of tafasitamab-lenalidomide (TL) in relapsed or refractory LBCL, patients receiving TL had higher rates of comorbidities and high-risk disease characteristics, and substantially lower progression-free survival and overall survival, compared with the L-MIND registration clinical trial for TL.

Abstract Purpose: The determinants of response or resistance to radioiodine (RAI) are unknown. We aimed to identify genomic and transcriptomic factors associated with structural responses to RAI treatment of metastatic thyroid cancer, which occur infrequently, and to test whether high MAPK pathway output was associated with RAI refractoriness. Experimental Design: Exceptional response to RAI was defined as reduction of tumor volume based on RECIST v1.1. We performed a retrospective case–control study of genomic and transcriptomic characteristics of exceptional responders (ER; n = 8) versus nonresponders (NR; n = 16) matched by histologic type and stage at presentation on a 1:2 ratio. Results: ER are enriched for mutations that activate MAPK through RAF dimerization (RAS, class 2 BRAF, RTK fusions), whereas NR are associated with BRAFV600E, which signals as a monomer and is unresponsive to negative feedback. ER have a lower MAPK transcriptional output and a higher thyroid differentiation score (TDS) than NR (P < 0.05). NR are enriched for 1q-gain (P < 0.05) and mutations of genes regulating mRNA splicing and the PI3K pathway. BRAFV600E tumors with 1q-gain have a lower TDS than BRAFV600E/1q-quiet tumors and transcriptomic signatures associated with metastatic propensity. Conclusions: ER tumors have a lower MAPK output and higher TDS than NR, whereas NR have a high frequency of BRAFV600E and 1q-gain. Molecular profiling of thyroid cancers and further functional validation of the key findings discriminating ER from NR may help predict response to RAI therapy.

Abstract Background: Diffuse large B-cell lymphoma (DLBCL) is frequently curable after frontline therapy, however, relapses can occur after achievement of a PET-negative complete remission (CR). Early detection of relapse may be associated with improved outcomes, particularly given the development of more active therapies for relapsed, refractory DLBCL. Controversy exists regarding the utility of post-therapy surveillance imaging which is associated with patient (pt) anxiety, radiation exposure, false-positive results, and cost, without clear overall survival benefit in retrospective studies (Thompson JCO 2014). A retrospective study found that serial minimal residual disease (MRD) monitoring during DLBCL surveillance could identify pts at risk of relapse before clinical evidence of disease (Roschewski Lancet Oncol 2015). In this multicenter prospective study, we assessed whether a next-generation immunosequencing (IS) MRD assay could be used for early detection of molecular relapse in DLBCL. Methods: Eligible pts with DLBCL or high-grade B-cell lymphoma (HGBCL) who received anthracycline-containing chemotherapy were enrolled across five cancer centers. In pts who achieved a PET-negative CR, serial peripheral blood samples were obtained every 3 months (mos) and CT scans every 6 mos for 2 years (yrs) post-treatment. The IS MRD assay (Adaptive Biotechnologies, Seattle, WA) that leverages multiplex PCR followed by NGS to identify and track rearrangements of IgH, V-J, D-J and IgK/L loci and translocations in Bcl1/2-IgH was used. MRD positive was defined as any detectable rearrangement and MRD undetectable as no evidence of rearrangement. Results: 500 pts were enrolled and 400 were evaluable (pre-treatment tumor pathology available, completed frontline treatment, and achieved PET-negative CR at end-of-treatment). Baseline characteristics were median age of 62 yrs (range 19-95), male sex 58%, advanced stage 61%, and poor-risk by R-IPI 42%. Histologies included DLBCL, NOS (88%), primary mediastinal B-cell lymphoma (6%), HGBCL (5%), T-cell rich B-cell lymphoma (3%), and other (1%). Pts received regimens including RCHOP x 6 cycles (37%), REPOCH x 6 cycles (20%), clinical trial (15%), combined modality therapy (RCHOP+RT) (9%), and other RCHOP variations (19%). Among the 400 evaluable pts, 44 relapses have occurred as of July 1, 2021. In 45% of pts (20/44), clinical relapse was detected using surveillance imaging alone (typically CT CAP with IV contrast) in an otherwise asymptomatic pt with a normal physical exam and laboratory evaluation . In 10% of pts (4/44), relapse was detected by patient-reported clinical symptoms alone. In 45% of pts (20/44), relapse was detected by imaging, clinical symptoms, and/or evaluation by an oncologist. With a median follow-up of 34 months, the 2-year PFS was 88.9% (85.8, 92.1). Advanced age, advanced stage, and poor-risk R-IPI were associated with inferior PFS. Of the 44 relapses, tumor-specific clonotypes were identified in 39 pts (4 failed quality control (QC), 1 failed calibration) and 38 pts had ≥1 sample available within 90 days of relapse. Of 356 patients in ongoing CR, tumor-specific clonotypes were identified in 279 patients (29 failed QC, 33 failed calibration, and 15 are pending sequencing). The patient-level prospective MRD results are shown in Figure 1. The overall sensitivity, specificity, positive predictive value, and negative predictive value of the IS MRD assay was 63% (24/38), 78% (218/279), 28% (24/85), and 94% (218/232), respectively. Plasma MRD detection had improved sensitivity and specificity compared with circulating cells. Among the 24 relapsed patients with a positive MRD result at or before relapse, the median anticipation of the test was 3 months (range 0 to 24 months). Conclusion: Overall outcomes are excellent for DLBCL and HGBCL pts who achieve PET-negative CR. In this multicenter prospective analysis with standardized follow up, a substantial proportion (45%) of clinical relapses are detected radiographically in asymptomatic pts, supporting the value of CT surveillance imaging in DLBCL, particularly for pts with advanced stage or high-risk disease. MRD assessment using the IS MRD assay had suboptimal sensitivity and specificity in the post-treatment surveillance setting in DLBCL. Further study of the clinical context and its correlation with test performance is ongoing. Figure 1 Figure 1. Disclosures Kumar: Kite Pharmaceuticals: Other: advisory board , Research Funding; Abbvie Pharmaceuticals: Research Funding; Celgene: Honoraria, Other: advisory board, Research Funding; Adaptive Biotechnologies, Celgene, Abbvie Pharmaceticals, Pharmacyclics, Seattle Genetics: Research Funding; Pharmacyclics: Research Funding; Astra Zeneca: Honoraria, Other: Advisory Board, Research Funding; Seattle Genetics: Research Funding. Westin: Novartis: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; Curis: Research Funding; Morphosys: Research Funding; ADC Therapeutics: Consultancy, Research Funding; Iksuda Therapeutics: Consultancy; Umoja: Consultancy; MorphoSys: Consultancy, Research Funding; Kite, a Gilead Company: Consultancy, Research Funding; AstraZeneca: Consultancy, Research Funding; Bristol Myers Squibb: Consultancy, Research Funding; 47 Inc: Research Funding. Schuster: TG Theraputics: Research Funding; Incyte: Research Funding; Adaptive Biotechnologies: Research Funding; Pharmacyclics: Research Funding; Merck: Research Funding; Genentech/Roche: Consultancy, Research Funding; Tessa Theraputics: Consultancy; Loxo Oncology: Consultancy; Juno Theraputics: Consultancy, Research Funding; BeiGene: Consultancy; Alimera Sciences: Consultancy; Acerta Pharma/AstraZeneca: Consultancy; Novartis: Consultancy, Honoraria, Patents & Royalties, Research Funding; Abbvie: Consultancy, Research Funding; Nordic Nanovector: Consultancy; Celgene: Consultancy, Honoraria, Research Funding. Nowakowski: Celgene, NanoString Technologies, MorphoSys: Research Funding; Celgene, MorphoSys, Genentech, Selvita, Debiopharm Group, Kite/Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees. Lossos: Lymphoma Research Foundation: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Consultancy; Janssen: Consultancy, Honoraria; NCI: Research Funding; University of Miami: Current Employment; NIH grants: Research Funding; Stanford University: Patents & Royalties; Verastem: Consultancy, Honoraria. Jacob: Adaptive Biotechnologies: Current Employment. Mullins: Adaptive Biotechnologies: Current Employment. Zelenetz: AstraZeneca: Honoraria; Amgen: Honoraria; Beigene: Honoraria, Other, Research Funding; Gilead: Honoraria, Research Funding; SecuraBio: Honoraria; Genentech/Roche: Honoraria, Research Funding; BMS/Celgene/JUNO: Honoraria, Other; Janssen: Honoraria; LFR: Other; MEI Pharma: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding; Verastem: Honoraria; MethylGene: Research Funding; NCCN: Other; Pharmacyclics: Honoraria; Novartis: Honoraria; Gilead: Honoraria; MorphoSys: Honoraria.

Background: Diffuse large B-cell lymphoma (DLBCL) is frequently curable after frontline therapy, however, relapses can occur after achievement of a PET-negative complete remission (CR). Early detection of relapse may be associated with improved outcomes with second-line curative intent therapy or novel therapies. Controversy exists regarding the utility of post-therapy surveillance imaging which is associated with patient (pt) anxiety, radiation exposure, false-positive results, and cost. A retrospective study found that serial minimal residual disease (MRD) monitoring during DLBCL surveillance could identify pts at risk of relapse before clinical evidence of disease (Roschewski, Lancet Oncol, 2015). In this multicenter prospective study, we assessed whether a next-generation sequencing (NGS)-based MRD assay could be used for early detection of molecular relapse in DLBCL. Methods: Eligible pts with DLBCL or high-grade B-cell lymphoma (HGBCL) who received anthracycline-containing chemotherapy were enrolled across five cancer centers. In pts who achieved a PET-negative CR, serial peripheral blood samples were obtained every 3 months (mos) and CT scans every 6 mos for 2 years (yrs) post-treatment. The clonoSEQ® next generation sequencing (NGS) MRD assay (Adaptive Biotechnologies, Seattle, WA) that leverages multiplex PCR followed by NGS to identify and track rearrangements of IgH, V-J, D-J and IgK/L loci and translocations in Bcl1/2-IgH was used. MRD positive was defined as any detectable rearrangement and MRD negative as no evidence of rearrangement. We also reported MRD positivity above the limit of detection (LOD) (observations required to have 95% reproducibility). Interim futility analysis was performed after approximately 50% of anticipated relapses occurred to assess the preliminary sensitivity of the assay. Progression-free survival (PFS) was defined as time from treatment start date to relapse or death. Results: 501 pts were enrolled and 401 were evaluable (pre-treatment tumor pathology available, completed frontline treatment, and achieved PET-negative CR at end-of-treatment). Baseline characteristics were median age of 62 yrs (range 19-95), male sex 58%, advanced stage 61%, and poor-risk by R-IPI 40% (Table 1). Histologies included DLBCL, NOS (86%), primary mediastinal B-cell lymphoma (6%), HGBCL (5%), T-cell rich B-cell lymphoma (1%), and other (1%). Pts received regimens including RCHOP x 6 cycles (36%), REPOCH x 6 cycles (20%), clinical trial (15%), combined modality therapy (RCHOP+RT) (10%), and other RCHOP variations (19%). Among the 401 evaluable pts, 44 relapses have occurred as of June 1, 2020. In 47% of pts (18/38), clinical relapse was detected using surveillance imaging alone (typically CT CAP with IV contrast) in an otherwise asymptomatic pt with a normal physical exam and laboratory evaluation. Clinical relapse was detected by clinical symptoms alone in 11% (4/28), by the evaluation of an oncologist alone in 0%, and by imaging and clinical symptoms and/or evaluation by an oncologist in 42% (16/38) (missing data in 6 pts). With a median follow-up of 2.2 yrs, the 2-yr PFS was 88.1% (84.8, 91.4) (Figure 1). Advanced age, advanced stage, and poor-risk R-IPI were associated with inferior PFS. Of the 44 relapses, 43 pts were included in the interim analysis and tumor-specific clonotypes were identified in 39 pts (91%). In 56% (22/39), the MRD assay was positive at or before clinical relapse. In 38% (15/39), the MRD assay was positive above the limit of detection at or prior to clinical relapse, with only 10 relapses detected more than 3 mos prior to relapse, reflecting the poor clinical sensitivity of the assay. The NGS-MRD assay was more sensitive in the acellular (plasma cell-free DNA) than in the cellular (circulating leukocytes) compartment. Results: Overall outcomes are excellent for DLBCL and HGBCL pts who achieve PET-negative complete remission. In interim analysis, surveillance MRD assessment using the clonoSEQ® assay fails to consistently identify pts at risk of recurrence before clinical evidence of relapse in DLBCL. In a prospective analysis, a substantial proportion (47%) of clinical relapses are detected by imaging in asymptomatic pts, supporting the value of CT surveillance imaging in DLBCL, particularly for pts with advanced stage or high-risk disease. Additional analyses are forthcoming for MRD assessment in all pts, including those in remission. Disclosures Kumar: Celgene: Research Funding; Pharmacyclics: Research Funding; Adaptive Biotechnologies,: Research Funding; AbbVie: Research Funding; Seattle Genetics: Research Funding; Celgene: Honoraria, Other: Honoraria for Advisory Board; Astra Zeneca: Honoraria, Other: Honoraria for Advisory Board; Kite Pharmaceuticals: Honoraria, Other: Honoraria for Advisory Board. Westin:Kite: Consultancy, Research Funding; Curis: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Amgen: Consultancy; Astra Zeneca: Consultancy, Research Funding; Morphosys: Consultancy, Research Funding; 47: Research Funding; Janssen: Consultancy, Research Funding; BMS: Consultancy, Research Funding. Nowakowski:Curis: Consultancy; Seattle Genetics: Consultancy; Nanostrings: Research Funding; MorphoSys: Consultancy, Research Funding; Roche: Consultancy, Research Funding; Celgene/BMS: Consultancy, Research Funding; Kite: Consultancy; Denovo: Consultancy; Kymera: Consultancy; Ryvu: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other. Lossos:Verastem: Consultancy, Honoraria; Seattle Genetics: Consultancy, Other; NCI: Research Funding; Stanford University: Patents & Royalties; Janssen Biotech: Honoraria; Janssen Scientific: Consultancy, Other. Batlevi:Life Sci, GLG, Juno/Celgene, Seattle Genetics, Kite: Consultancy; Janssen, Novartis, Epizyme, Xynomics, Bayer, Autolus, Roche/Genentech: Research Funding. Drullinsky:Roche: Research Funding; Novartis: Research Funding. Gerecitano:Janssen: Current Employment. Hamlin:Celgene: Consultancy; Karyopharm: Consultancy; Juno Therapeutics: Consultancy; Portola: Research Funding; Molecular Templates: Research Funding; Incyte: Research Funding; J&J Pharmaceuticals: Research Funding; Portola Pharmaceutics: Consultancy. Horwitz:ASTEX: Consultancy; Affirmed: Consultancy; Vividion Therapeutics: Consultancy; Verastem: Consultancy, Research Funding; Myeloid Therapeutics: Consultancy; Miragen: Consultancy; Kura Oncology: Consultancy; Janssen: Consultancy; GlaxoSmithKline: Consultancy; Daiichi Sankyo: Research Funding; C4 Therapeutics: Consultancy; Beigene: Consultancy; Portola: Consultancy, Research Funding; Mundipharma: Consultancy; Innate Pharma: Consultancy; Corvus: Consultancy; Trillium: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding; Millenium/Takeda: Consultancy, Research Funding; Kyowa Hakka Kirin: Consultancy, Research Funding; Infinity/Verastem: Research Funding; Forty Seven: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Aileron: Consultancy, Research Funding; ADCT Therapeutics: Consultancy, Research Funding. Jacob:Adaptive Biotechnologies: Current Employment, Current equity holder in publicly-traded company. Joffe:AstraZeneca: Membership on an entity's Board of Directors or advisory committees; Epizyme: Membership on an entity's Board of Directors or advisory committees. von Keudell:Bayer: Research Funding; Pharmacyclics: Research Funding; Genentech: Research Funding. Lahoud:MorphoSys: Other: Advisory Board. Matasar:Bayer: Consultancy, Honoraria, Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Rocket Medical: Consultancy, Research Funding; Teva: Consultancy; F. Hoffmann-La Roche Ltd: Consultancy, Honoraria, Research Funding; GlaxoSmithKline: Honoraria, Research Funding; Takeda: Consultancy, Honoraria; Daiichi Sankyo: Consultancy; IGM Biosciences: Research Funding; Janssen: Honoraria, Research Funding; Pharmacyclics: Honoraria, Research Funding; Immunovaccine Technologies: Honoraria, Research Funding; Merck: Consultancy; Juno Therapeutics: Consultancy; Genentech, Inc.: Consultancy, Honoraria, Research Funding. Mullins:Adaptive Biotechnologies: Current Employment, Other: shareholder. Noy:Pharmacyclics: Research Funding; NIH: Research Funding; Rafael Pharma: Research Funding; Janssen: Consultancy; Pharmacyclics: Consultancy; Medscape: Consultancy; Targeted Oncology: Consultancy; Morphosys: Consultancy. Straus:Seattle Genetics: Consultancy, Membership on an entity's Board of Directors or advisory committees; ASH: Other: Conference in December 2019 on HL to other physicians during ASH; Elsevier: Membership on an entity's Board of Directors or advisory committees, Other: CME writer; OncLive: Speakers Bureau; Takeda Pharmaceuticals: Research Funding, Speakers Bureau; NY Lymphoma Rounds: Consultancy; Targeted Oncology: Consultancy, Speakers Bureau; Imedex, Inc.: Speakers Bureau; Karyopharm Therapeutics: Membership on an entity's Board of Directors or advisory committees. Younes:Takeda: Consultancy; HCM: Consultancy; AstraZeneca: Current Employment; Novartis: Consultancy; Daiichi Sankyo: Consultancy; Janssen: Consultancy; Epizyme: Consultancy; BMS: Consultancy; BioPath: Consultancy; Curis: Consultancy. Zelenetz:MEI Pharma: Research Funding; MorphoSys: Research Funding; Sandoz: Research Funding; Celgene: Research Funding; Roche: Research Funding; Gilead: Research Funding; Genentech/Roche: Consultancy; Gilead: Consultancy; Celgene: Consultancy; Janssen: Consultancy; Amgen: Consultancy; Novartis: Consultancy; Adaptive Biotechnology: Consultancy; BeiGene: Membership on an entity's Board of Directors or advisory committees.

Background: With the incorporation of positron emission tomography (PET) imaging as part of the standard staging evaluation of follicular lymphoma (FL), it is generally recommended to obtain the diagnostic biopsy from a lesion with the highest standardized uptake value (SUV) to rule out de novo histologic transformation (HT). In some cases such an approach might be impractical, while in other cases a biopsy from a diseased area with a high SUV may still demonstrate an indolent histology. To date, there is no data to guide treatment choices in patients (pts) with FL with high SUVmax but with no documented evidence of HT. Specifically, it remains unclear whether anthracycline-containing regimens, such as R-CHOP, provide a better outcome than R-Bendamustine (BR). Furthermore, it is unknown whether rituximab (R) maintenance is beneficial in this setting. Therefore, we aimed to compare the efficacy of R-CHOP vs BR in newly diagnosed FL pts with high SUVmax at baseline PET and to clarify the role of maintenance. Patients and Methods: We retrospectively identified 261 consecutive pts with newly diagnosed biopsy-proven FL1-3A and a SUVmax≥13 on baseline PET, who were treated with frontline R-CHOP (n=183) or BR (n=78) at 7 US cancer centers based on the physician's choice. Progression-free survival (PFS) was calculated from starting treatment until progression, relapse or death. Cut-offs of SUVmax ≥13≤18 and SUVmax>18 were used for sub-analysis (Haematologica;2020;105:1907-1913). Results: Median age was 59 years. The baseline characteristics of the two groups differed significantly for a younger age (58 vs 62 years, p=0.009), a higher rate of B-symptoms (26% vs 10%, p=0.005) and baseline SUVmax>18 (49% vs 36%, p=0.04) in the R-CHOP group. A diagnostic biopsy was obtained from the site at the highest SUV in 129 (71%) and 43 (55%) pts, respectively (p=0.01). These suggest a potential selection of R-CHOP in pts with adverse features. At the end of therapy (EoT), R-CHOP treated pts achieved higher PET-CT complete response rates (CR 82% vs 69%, p=0.02). This superiority held in pts with diagnostic biopsy at the highest SUV site (CR 83% vs 67%, p=0.03), but not in the others (CR 80% vs 71%, p=0.37). Progression occurred at EoT in 11 and 14 pts receiving R-CHOP and BR (6% vs 18%, p=0.02), with a higher rate of HT in the BR group (13% vs 4%, p=0.006). After a median follow-up of 76 months (range, 4-208 months), there was no significant difference in PFS between R-CHOP and BR treated pts (hazard ratio [HR] 1.22, p=0.34). PFS was strongly associated with FLIPI 2 (HR 2.32, p=0.01) and 3-5 (HR 2.69, p=0.003) in the univariate as well as in the multivariate analysis (FLIPI 2 HR 2.19, p=0.02; FLIPI 3-5 HR 2.51, p=0.01). There was a trend toward overall survival (OS) benefit in the R-CHOP group (Fig.1A). In the univariate analysis for OS, BR regimen (HR 2.12, p=0.03), age >60 (HR 2.54, p=0.006), FLIPI 3-5 (HR 5.13, p=0.03) and biopsy at the highest SUV site (HR 0.44, p=0.01) were prognostic, however none of those remained significant in the multivariate analysis (BR regimen HR 1.84, p=0.09; age >60 HR 1.92, p=0.08; FLIPI 3-5 HR 3.11, p=0.14; biopsy at the highest SUV site HR 0.60, p=0.13; SUVmax>18 HR 1.87, p=0.055). Among pts with EoT response after R-CHOP or BR (n=170 and n=64, respectively), one third in each group (36% vs 41%, respectively) received R-maintenance for a median of 8 administrations (range, 2-12). A significant PFS advantage (landmark analysis) was observed with R-maintenance (Fig.1B; HR 0.53, p=0.02); however, this did not translate in survival benefit (HR 0.67, p=0.49). In a multivariable model, R-maintenance (HR 0.53, p=0.02), FLIPI 2 (HR 2.47, p=0.03) and 3-5 (HR 2.79, p=0.01) remained independent prognosticators of PFS, while no parameters significantly affected OS. The 2-year HT rate (10% vs 17%) and cumulative incidence did not statistically differ between R-CHOP and BR groups (Fig.1C, p=0.159). Early progression (POD24) occurred in 43 and 22 pts who received R-CHOP and BR, respectively (24% vs 28%) and resulted in a significantly higher risk of death (HR 4.12, p=0.006). Conclusion: In newly diagnosed FL pts with SUVmax≥13 at baseline PET, R-CHOP was more effective in achieving CR and reducing the risk of early HT compared with BR, and it was associated with a trend toward survival advantage. Rituximab maintenance significantly prolonged PFS. A prospective evaluation with a larger population will be needed to confirm our findings. Disclosures Joffe: Epizyme: Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Membership on an entity's Board of Directors or advisory committees. Ruella:Abclon, BMS, NanoString: Consultancy; Abclon: Consultancy, Research Funding; UPenn/Novartis: Patents & Royalties. Svoboda:Adaptive: Consultancy; Astra-Zeneca: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Imbrium: Consultancy; Incyte: Research Funding; Pharmacyclics: Consultancy, Research Funding; Merck: Research Funding; Seattle Genetics: Consultancy, Research Funding; TG: Research Funding; Genmab: Consultancy; Atara: Consultancy. Witzig:Immune Design: Research Funding; Spectrum: Consultancy; Karyopharm Therapeutics: Research Funding; Acerta: Research Funding; Celgene: Consultancy, Research Funding; AbbVie: Consultancy; MorphSys: Consultancy; Incyte: Consultancy. Smith:TG Therapeutics: Consultancy, Research Funding; Janssen: Consultancy; BMS: Consultancy; Celgene: Consultancy, Research Funding; Pharmacyclics: Research Funding; Karyopharm: Consultancy, Research Funding; FortySeven: Research Funding; Acerta: Research Funding; Genentech/Roche: Consultancy, Other: Support of parent study and funding of editorial support, Research Funding. Armand:Affimed: Consultancy, Research Funding; Otsuka: Research Funding; Bristol-Myers Squibb: Consultancy, Honoraria, Research Funding; IGM: Research Funding; Infinity: Consultancy; Genentech: Research Funding; Sigma Tau: Research Funding; Celgene: Consultancy; Adaptive: Consultancy, Research Funding; Tensha: Research Funding; Roche: Research Funding; Merck & Co., Inc.: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy; ADC Therapeutics: Consultancy. Nastoupil:Janssen: Honoraria, Research Funding; LAM Therapeutics: Research Funding; Gilead/KITE: Honoraria; Gamida Cell: Honoraria; TG Therapeutics: Honoraria, Research Funding; Merck: Research Funding; Novartis: Honoraria, Research Funding; Genentech, Inc.: Honoraria, Research Funding; Karus Therapeutics: Research Funding; Bayer: Honoraria; Celgene: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding. Ansell:Takeda: Research Funding; Regeneron: Research Funding; Bristol Myers Squibb: Research Funding; Seattle Genetics: Research Funding; Trillium: Research Funding; Affimed: Research Funding; AI Therapeutics: Research Funding; ADC Therapeutics: Research Funding. Zelenetz:Novartis: Consultancy; Adaptive Biotechnology: Consultancy; Genentech/Roche: Consultancy; Gilead: Consultancy; Gilead: Research Funding; Celgene: Consultancy; Roche: Research Funding; Amgen: Consultancy; BeiGene: Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy; Sandoz: Research Funding; Celgene: Research Funding; MorphoSys: Research Funding; MEI Pharma: Research Funding. Younes:BioPath, Xynomic, Epizyme, and F. Hoffmann-La Roche: Consultancy; Janssen, Curis, Merck, Bristol-Myers Squibb, Syndax Pharmaceuticals, F. Hoffmann-La Roche, Curis (Inst), Johnson & Johnson (Inst), Novartis (Inst): Research Funding; Janssen, AbbVie, Merck, Curis, Epizyme, F. Hoffmann-La Roche, Takeda, Bristol-Myers Squibb, Bayer HealthCare Pharmaceuticals, Celgene, Incyte, Janssen Pharmaceuticals, Merck, Sanofi, Seattle Genetics, Takeda Millennium: Honoraria; AstraZeneca: Current Employment; MSKCC: Ended employment in the past 24 months.

Chromophobe renal cell carcinoma (chRCC) typically shows ~7 chromosome losses (1, 2, 6, 10, 13, 17, and 21) and ~31 exonic somatic mutations, yet carries ~5%–10% metastatic incidence. Since extensive chromosomal losses can generate proteotoxic stress and compromise cellular proliferation, it is intriguing how chRCC, a tumor with extensive chromosome losses and a low number of somatic mutations, can develop lethal metastases. Genomic features distinguishing metastatic from nonmetastatic chRCC are unknown. An integrated approach, including whole-genome sequencing (WGS), targeted ultradeep cancer gene sequencing, and chromosome analyses (FACETS, OncoScan, and FISH), was performed on 79 chRCC patients including 38 metastatic (M-chRCC) cases. We demonstrate that TP53 mutations (58%), PTEN mutations (24%), and imbalanced chromosome duplication (ICD, duplication of ≥ 3 chromosomes) (25%) were enriched in M-chRCC. Reconstruction of the subclonal composition of paired primary-metastatic chRCC tumors supports the role of TP53 , PTEN , and ICD in metastatic evolution. Finally, the presence of these 3 genomic features in primary tumors of both The Cancer Genome Atlas kidney chromophobe (KICH) ( n = 64) and M-chRCC ( n = 35) cohorts was associated with worse survival. In summary, our study provides genomic insights into the metastatic progression of chRCC and identifies TP53 mutations, PTEN mutations, and ICD as high-risk features.

513 Background: Chromophobe renal cell carcinoma (chRCC) is the third most common histologic subtype of kidney cancer. While most of these tumors have an indolent behavior, 7% of patients with chRCC develop metastases, with no currently available standard of care. The Cancer Genome Atlas characterized chRCC, highlighting pathognomonic single copy chromosomal losses of 1, 2, 6, 10, 13 and 17, as well as a minimal mutation burden distinguishing it from all other cancer types. However, only 15% of the analyzed patients had advanced disease. We analyzed metastatic chRCC to further characterize these tumors and elucidate mechanisms leading to aggressive disease using a variety of next generation and whole genome sequencing. Methods: Our cohort of metastatic chRCC consisted of 40 patients with available clinical and pathologic data. Whole genome sequencing (WGS) was performed on 6 patients (4 primary tumors and 2 metastases), 42 additional samples from 33 patients were analyzed using targeted next-generation sequencing (MSK-IMPACT). Notably, we were able to collect and analyze matched primary and metastatic tumors from 7 patients. As control cohort 27 non-metastatic chRCC tumors were sequenced with MSK-IMPACT. Copy number patterns were computed with OncoSNP seq and FACETS. Results: The most commonly mutated genes in the aggressive chRCC tumors were TP53 and PTEN (WGS: TP53 67 %, PTEN 33%; MSK-IMPACT: TP53 61%, PTEN 27%). No other genes were mutated frequently. Primary tumor samples of chRCC did show the typical pattern of chromosomal losses in 1, 2, 6, 10, 13 and 17. Interestingly, these canonical losses could not be detected in the metastases even when accounting for tumor purity. Conclusions: TP53 and PTEN mutations are highly enriched in both primary and metastatic tumors of aggressive chRCC compared to the non-aggressive tumors and likely play a critical role in disease progression. More intriguingly, the observation of differential copy numbers in matched primary and metastatic tumors suggest whole genome or whole chromosome events in these samples. We are currently employing different bioinformatic and cytogenetic platforms to validate our novel hypothesis of chromosomal events as driver for metastatic development in chRCC.