Tun, Han W.

Background: The tumor microenvironment (TME) of MM is characterized by an immunosuppressive milieu fostering MM growth. The impact of tumor associated macrophages (TAM) has not been well-studied in the MM TME. We evaluated the bone marrow biopsies (BMBx) obtained at the initial diagnosis of MM and evaluated the correlation between the number of CD68+ macrophages and clinical parameters and outcomes. Methods: We evaluated the BMBx at initial diagnosis of 34 consecutive MM patients (pts) diagnosed between 2007-2016 at Mayo Clinic Florida. Immunohistochemistry (IHC) was performed with an anti-CD68 (KP1) antibody to identify and count CD68+ TAMs. Survival was analyzed with the Kaplan-Meier method. Chi-square tests were performed to study the correlation between the number of CD68+ TAMs and various clinical parameters. Results: Nineteen (56%) pts were male, 29 (85%) were caucasian. Median age at MM diagnosis was 58.5 years (95% CI 57-63), 18 (53%) pts has ISS I/II disease, 13 (38%) pts had ISS III disease, 3 (9%) has unknown ISS. Eight (24%) had high risk cytogenetics; 4(12%) had del17p, 2 (6%) had t(14;16), 1(3%) had 1q amplification, 3 (9%) had t(4;14). Eight (24%) had t(11;14). Twenty nine (85%) pts underwent autologous transplantation, 11(32%) received maintenance therapy. Overall response rate (≥partial response) to induction therapy was 100%. The ≥ very good partial response (VGPR) rate was 73.5%. Median number of induction cycles was 4.5 (95% CI 4.8-8.3). Twelve (35%) pts received lenalidomide (R)-dexamethasone (D) induction (RD), 9 (26%) received bortezomib (V)-cyclophosphamide(C)-D (VCD) induction, 7 (21%) received VRD induction, 5(15%) received VD induction and 1(3%) received CRD induction. The median follow-up was 92 months (m) (95% CI 85-99) The median progression free survival (mPFS) of the pt population was 40m (95% CI 27-68) and the median overall survival (mOS) was 96m (95% CI 81-126). Mean CD68+ TAM count was 12.5% (95% CI 8.1-16). There was a trend towards improved PFS for patients with ≥5% vs. <5% CD68+ TAM (47m vs. 36m, p=0.055) and there was improved OS for patients with ≥5% vs. <5% CD68+ TAM (101m vs. 73m, p=0.042, Figure 1) in their initial diagnostic BMBx. Pts with high risk cytogenetics did not have a significantly different CD68+ TAM (8.6%vs.12.8%, p=0.363) compared to those with standard risk cytogenetics. Pts with ISS I/II disease were more likely to have ≥5% CD68+ TAM in their diagnosis BMBx compared to patients with ISS III disease, χ²=8.58, p=0.003. Pts who achieved ≥VGPR to induction therapy were more likely to have ≥5% CD68+ TAM in their diagnosis BMBx compared to those who achieved <VGPR; χ²=5.35, p=0.020. Pts who received R-based induction and had ≥5% CD68+ TAM in their diagnosis BMBx had superior OS (96m vs. 62m, p=0.044) compared to those with <5%.This finding was not seen in patients who received V-based induction (p=0.33). Conclusion: Pts with ≥5% CD68+ TAM in their initial diagnostic BMBx are more likely to have deeper responses to induction therapy as well as superior OS. In pts induced with an R-based regimen, increased CD68+ TAM was associated with significantly better OS raising the possibility of a therapeutic and mechanistic role of TAM in R-related therapeutic effect. ≥5% CD68+ TAM were noted in patients with lower risk disease as defined by ISS stage but not by cytogenetics. Further exploration of the role of TAM in the biology of MM and its impact on clinical and therapeutic outcomes is warranted. Disclosures Alhaj Moustafa: Acrotech: Consultancy. Tun:DTRM Biopharma: Research Funding; Acrotech: Research Funding; Bristol-Myers Squibb: Research Funding; Celgene: Research Funding; Mundipharma: Research Funding; Curis: Research Funding; TG Therapeutics: Research Funding.

Introduction The molecular basis for the clinical heterogeneity observed in DLBCL was initially elucidated with gene expression profiling, identifying three distinct subgroups with prognostic relevance based on COO namely activated B-cell like (ABC), germinal center B-cell like (GCB) and a type 3 subtype. Shortly afterwards the Han's algorithm was developed allowing for widespread applicability and correlation of gene expression with protein expression. GCB profile at diagnosis is generally associated with superior long term outcomes compared to non-GCB in patients treated with conventional chemo-immunotherapy. Patients with relapsed/refractory disease (R/R) after front-line therapy undergo salvage treatment and, upon demonstration of objective response, proceed with high dose therapy and autologous transplantation (auto-HCT). Whether COO by Han's algorithm retains its prognostic significance post auto-HCT in patients with R/R DLBCL is not well established. Methods A retrospective analysis was carried out using the Mayo database across all three sites. It included all patients between 18-75 years of age who were diagnosed with de-novo DLBCL and underwent first auto-HCT for R/R disease. Patients must have received salvage treatment and shown chemotherapy sensitive disease. Patients with transformed DLBCL or other variants and those who underwent auto-HCT in first complete remission for high risk disease were excluded. Patients who had less than a partial response at time of transplantation and still underwent auto-HCT were also excluded. Primary endpoints included overall survival (OS); relapse and relapse-free survival (RFS). Continuous variables were summarized as mean (standard deviation) and median (range). Categorical variables were reported as frequency (percentage). Continuous baseline variables were compared between GCB and non-GCB using Wilcoxon rank sum test and categorical baseline variables were compared with Chi-squared test. Kaplan-Meier method was used to estimate 5 and 10-year rates of freedom from long-term events and draw corresponding survival curves. Multivariate Cox regression models were used to evaluate the impact of cell of origin on long-term survival after adjusting for baseline factors. All tests were two-sided with alpha level set at 0.05 for statistical significance. Results A total of 357 patients underwent auto-HCT between 2005 and 2018. Cell of origin was determined for 284 patients and these were included in the analysis. Median age was 61 (range: 19-78) years, and 64% patients were male. GCB and non-GCB patients did not differ significantly with regards to baseline factors (Table 1). During a median follow up of 1.7 years, 139 patients died, 151 had relapse and 175 either died or had relapse. Five year OS for GCB patients versus (vs) non-GCB was at 44% vs 64% (p=0.004) (Figure 1); relapse was at 67% vs 49% (p=0.012) and RFS was at 28% vs 50% (p=0.003). The difference between GCB and non-GCB groups remained statistically significant in multivariate analysis, with GCB patients 60% more likely to die and 50% more likely to experience relapse compared to non-GCB patients. The only other factor that retained significance in multivariate analysis for both endpoints was response at the time of transplant (Table 2A-C). Conclusions In this analysis, GCB DLBCL results in worse OS and higher relapse vs. non-GCB DLBCL following an auto-HCT. It is unclear if relapse/progression of GCB subtype after front-line therapy alters its natural history into a more aggressive disease. Disclosures Ansell: Trillium: Research Funding; ADC Therapeutics: Research Funding; Affimed: Research Funding; Bristol Myers Squibb: Research Funding; AI Therapeutics: Research Funding; Takeda: Research Funding; Seattle Genetics: Research Funding; Regeneron: Research Funding. Foran:Xencor: Research Funding; Trillium: Research Funding; Takeda: Research Funding; Kura Oncology: Research Funding; Aptose: Research Funding; Aprea: Research Funding; Actinium: Research Funding; Boehringer Ingelheim: Research Funding; Abbvie: Research Funding; BMS: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Servier: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Revolution Medicine: Consultancy; H3Biosciences: Research Funding; Agios: Honoraria, Research Funding. Tun:Celgene: Research Funding; Mundipharma: Research Funding; Curis: Research Funding; TG Therapeutics: Research Funding; Acrotech: Research Funding; DTRM Biopharma: Research Funding; Bristol-Myers Squibb: Research Funding. Kharfan-Dabaja:Daiichi Sankyo: Consultancy; Pharmacyclics: Consultancy.

Introduction: With a median overall survival (OS) measured in months, successful treatment of Richter's transformation (RT) of chronic lymphocytic leukemia (CLL) to diffuse large B-cell lymphoma (DLBCL) remains a major unmet medical need. While targeted agents, such as Bruton tyrosine kinase inhibitor (BTKi) monotherapy, have greatly improved outcomes for patients (pts) with CLL and some B-cell lymphomas, available BTKi therapies have been ineffective for RT, as well as for large cell transformation of indolent B-cell lymphomas and relapsed/refractory (r/r) DLBCL, which rapidly develop mechanisms of resistance by activation of downstream targets of BTKi or upregulation of alternative/parallel pathways. Focusing on a synthetic lethality approach via in vitro and in vivo studies, we discovered that concurrent inhibition of BTK & mTOR targets plus an IMiD synergistically kill malignant B-cells. DTRM-555 is an optimized oral triple combination of a novel irreversible BTKi DTRMWXHS-12 (DTRM-12), everolimus (EV) and pomalidomide (POM). This once daily therapy was tested in a stepwise, phase I, multicenter study in pts with the greatest unmet medical needs. Here we present results for this novel combination therapy in pts with RT, and r/r DLBCL. Methods: We conducted a phase I (3+3 design), first in human trial exploring DTRM-555 in adult pts with B-cell lymphomas with no available standard therapies (NCT02900716) at 6 US cancer centers. Our goal was to determine the optimal dose for DTRM-555. In phase Ia, an MTD was not reached for DTRM-12 monotherapy; In phase Ib and expansion cohorts, we evaluated double (DTRM-12/EV at 200mg/5mg or 300mg/5mg) and triple combinations (DTRM-12/EV/POM at 200mg/5mg/2mg or 300mg/5mg/2mg) administered once daily for 21 days of a 28-day cycle, until disease progression or unacceptable toxicity. The primary endpoint was safety and the dose limiting toxicity (DLT) period was cycle 1 (28 days). Secondary endpoints included overall response rate (ORR; Cheson 2014), duration of response (DOR), and DTRM-12 pharmacokinetics. The trial began on 9/27/2016 and completed enrollment with evaluable follow-up data cut-off date on 08/06/2020. Results: 39 pts were enrolled and treated, including 24 with RT (n=12) or r/r DLBCL (n=12). The safety analyses included all 39 pts treated with combination therapies while efficacy analyses were focused on RT and r/r DLBCL. Baseline characteristics (n=39): 66% male, median age 71 years (range 43-94) and 94% white. For the entire study cohort, median number of prior therapies was 3 (range 1-10), 49% had been treated with prior BTKi monotherapy,13% prior CAR-T or stem cell transplant (SCT) and 59% ≥1 prior small molecule targeted agent. For pts with RT and r/r DLBCL (n=24), median prior therapies were 5 (range 1-10) and 2 (range 10), respectively. Table 1 summarizes prior therapies for the 24 RT and r/r DLBCL pts. Table 2 describes Grade 3 and 4 related AEs for 39 pts treated with the combination therapies. AEs were manageable and similar to known AEs for BTKi, EV or POM, with a total of 4 DLTs observed with combination therapies. The most common AEs were hematological events; specifically, thrombocytopenia, neutropenia, and anemia. The MTD of DTRM-555 was determined to be DTRM-12 200mg, EV 5mg, & POM 2mg. For 11 evaluable RT pts, ORR was 45% (1 CR, 4 PR); 1 RT pt has not undergone first response assessment. For 10 evaluable DLBCL pts, ORR was 60% (2 CR, 4 PR). Responders with RT or r/r DLBCL have durable responses (Figure 1). Kaplan Meier estimated median duration of response for RT and DLBCL pts was 15 months as of the cut-off. Dose dependent DTRM-12 drug plasma levels were observed in all arms with minimal inter-pt variability. Conclusions: This clinical trial met its primary endpoint. The once-daily oral triple combination therapy DTRM-555 has an acceptable safety profile. Encouraging clinical activity was observed in several high-risk, multi-refractory pts with RT (median 5 prior therapies, ORR 45%) or r/r DLBCL (median 2 prior therapies, ORR 60%), including pts previously treated with targeted therapies, cellular therapies, checkpoint inhibitors and other experimental agents. A phase II US expansion study is underway targeting pts with RT, r/r DLBCL, r/r transformed follicular lymphoma and BTKi/BCL2 inhibitor exposed r/r CLL pts. Disclosures Mato: Adaptive: Consultancy, Research Funding; TG Therapeutics: Consultancy, Other: DSMB, Research Funding; AbbVie: Consultancy, Research Funding; AstraZeneca: Consultancy, Research Funding; BeiGene: Consultancy; LOXO: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding. Schuster:AlloGene, AstraZeneca, BeiGene, Genentech, Inc./ F. Hoffmann-La Roche, Juno/Celgene, Loxo Oncology, Nordic Nanovector, Novartis, Tessa Therapeutics: Consultancy, Honoraria; Novartis, Genentech, Inc./ F. Hoffmann-La Roche: Research Funding. Ding:DTRM: Research Funding; Astra Zeneca: Research Funding; Abbvie: Research Funding; Octapharma: Membership on an entity's Board of Directors or advisory committees; MEI Pharma: Membership on an entity's Board of Directors or advisory committees; alexion: Membership on an entity's Board of Directors or advisory committees; Beigene: Membership on an entity's Board of Directors or advisory committees; Merck: Membership on an entity's Board of Directors or advisory committees, Research Funding. Brander:Tolero: Research Funding; NCCN: Other; Teva: Consultancy, Honoraria; Novartis: Consultancy, Other; NCCN: Other; Verastem: Consultancy, Honoraria, Other, Research Funding; TG Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; Pfizer: Consultancy, Other; Pharmacyclics LLC, an AbbVie Company: Consultancy, Honoraria, Other, Research Funding; MEI Pharma: Other, Research Funding; Juno/Celgene/BMS: Other, Research Funding; Genentech: Consultancy, Honoraria, Other, Research Funding; DTRM: Other, Research Funding; AstraZeneca: Consultancy, Honoraria, Other, Research Funding; BeiGene: Other, Research Funding; Ascentage: Other, Research Funding; ArQule: Consultancy, Other, Research Funding; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; Tolero: Research Funding; Teva: Consultancy, Honoraria; Novartis: Consultancy, Other. Tun:Bristol-Myers Squibb: Research Funding; Celgene: Research Funding; Mundipharma: Research Funding; Curis: Research Funding; TG Therapeutics: Research Funding; Acrotech: Research Funding; DTRM Biopharma: Research Funding. He:DTRM Biopharma LLC: Current Employment. Kearney:DTRM Biopharma LLC: Current Employment. Gui:DTRM Biopharma LLC: Current Employment. McKinlay:DTRM Biopharma LLC: Current Employment. Roeker:American Society of Hematology: Research Funding; AbbVie: Other: spouse with minority ownership interest ; Abbott Laboratories: Other: spouse with minority ownership interest . Huntington:Pharmacyclics: Honoraria; Novartis: Consultancy; Genentech: Consultancy; DTRM: Research Funding; AbbVie: Consultancy; Astrazeneca: Honoraria; Bayer: Consultancy, Honoraria; Celgene: Consultancy, Research Funding; TG Therapeutics: Research Funding.

Chloroethylagelastatin A (CEAA) is an analogue of agelastatin A (AA), a natural alkaloid derived from a marine sponge. It is under development for therapeutic use against brain tumors as it has excellent central nervous system (CNS) penetration and pre-clinical therapeutic activity against brain tumors. Recently, AA was shown to inhibit protein synthesis by binding to the ribosomal A-site. In this study, we developed a novel virtual screening platform to perform a comprehensive screening of various AA analogues showing that AA analogues with proven therapeutic activity including CEAA have significant ribosomal binding capacity whereas therapeutically inactive analogues show poor ribosomal binding and revealing structural fingerprint features essential for drug-ribosome interactions. In particular, CEAA was found to have greater ribosomal binding capacity than AA. Biological tests showed that CEAA binds the ribosome and contributes to protein synthesis inhibition. Our findings suggest that CEAA may possess ribosomal inhibitor activity and that our virtual screening platform may be a useful tool in discovery and development of novel ribosomal inhibitors.

IgG4-related disease (IgG4RD) with intracranial involvement is rare. We report a 56-year-old male who had an excellent response to rituximab and dexamethasone after going undiagnosed for 5 years. After 3 years of rituximab maintenance, he has no evidence of disease on brain MRI.

AbstractALK‐positive ALCL can lead to rapid irreversible destruction of the optic pathway. Early treatment should be instituted in patients with CNS involvement or those at increased CNS risk.

AbstractThis case illustrates an unusual presentation of paraneoplastic myositis in stage IV follicular lymphoma managed with high‐dose steroids, a previously unreported entity in the literature.

A 26-year-old female developed bilateral blindness after a complete remission for ALK-positive ALCL. Initial workup showed neurolymphomatosis involving the bilateral optic nerves. She underwent hematopoietic cell transplantation and she remained in complete remission after 1 year; however her vision never improved. ALCL likely led to destruction of the optic pathway.

e20044 Background: Primary Cutaneous Diffuse Large B-cell Lymphoma, Leg-type (PCDLBCL) is a rare lymphoma comprising 4% of all cutaneous lymphomas with an aggressive clinical course. We investigated disease characteristics and outcomes among patients PCDLBCL. Methods: Following IRB approval, we identified patients retrospectively with PCDLBCL treated at the Mayo Clinic Cancer Center 1998-2019. Results: 45 pts were identified with a median age of 71 years (Range- 48-95) and 28 (62%) were female. Disease locations were legs (62%), arms (22%), head (11%), trunk (2%) and multiple sites (2%). At diagnosis, (51%) had a single lesion, (29%) had multiple lesions in 1-2 contiguous regions, (16%) had multiple lesions in non-contiguous regions or > 2 regions and data was not available (4%). Immunohistochemistry showed positive staining for BCL-2 (92%), BCL-6 (76%), c-MYC (62%), MUM1 (95%), CD10 (11%), and cytoplasmic IgM (8/9- 89%). By Han’s criteria, (95%) had activated B cell lymphoma (ABC). Median Ki-67 was 90% (range, 50,100%). 9/12 (75%) were positive for MYD88 L265P mutation. 13/21 (62%) were double expressor and 3/22 (14%) had double hit lymphoma. 37/45 (82%) had ECOG < 2. LDH was elevated in 13/37 (35%). The median number of therapies was 1 (range; 1-11). The initial treatments were chemo-radiation (30%), chemo alone (38%), rituximab alone (11%), radiation (RT) alone (16%), rituximab-RT (2.5%), and surgical (2.5%). The median follow-up time for the whole cohort was 80 months (95% CI; 32, 169). The median progression free survival and overall survival (OS) were 20 months (95% CI; 12, 34) and 80 months (95% CI; 48, 119). 22/45 (49%) are alive. The cause of death was disease-related in 11/23 (48%). The median number of relapses was 1 (range; 0, 11) with (60%) relapsed after first line. 4/45 pts had autologous stem cell transplant after relapse. 7/45 (16%) had a systemic relapse at a median time of 35 months from diagnosis (range; 16, 112). Age above 60 years was associated with worse OS; 70 months (95% CI; 30, 99) vs NR (95% CI; 135, NR), p = 0.025. ECOG performance status < 2 was associated with better OS, NR months (95% CI; 80, NR) vs 48 months (95% CI; 3.3, 88),p = 0.0003. 1 pt received Ibrutinib on 11th relapse and had 3 years of PFS. Conclusions: PCDLBCL is predominantly ABC type, affects elderly pts and is characterized by multiple cutaneous relapses followed in some cases by systemic relapses. Increased age and poor performance status had a negative impact on OS. High incidence of MYD88 L265P mutation is observed in PCDLBCL similar to immune-privileged site lymphomas.

e20036 Background: Hepatosplenic T cell lymphoma (HSTL) is a rare subtype of mature T cell lymphomas accounting for less than 1 percent of non-Hodgkin lymphomas. it has been associated with poor prognosis. It typically involves sinusoids in the spleen, liver, and bone marrow. Methods: Following IRB approval, we retrospectively evaluated patients with HSTL treated at the Mayo Clinic Cancer Center 1996-2019. Kaplan-Meier survival analysis and univariate analysis to identify prognostic factors were performed. We investigated clinical characteristics and outcomes among patients with HSTL. Results: 22 patients (15 males) with median age of 45.5 years (range- 15.5-80.6) were identified. The majority of patients had B symptoms (12/22), cyotpenias (20/22), massive splenomegaly (16/22), liver involvement (13/22), and/or bone marrow involvement (14/22). Additionally, 42% tested positive for peripheral blood involvement and 8/22 (36%) were on chronic immunosuppression related to solid organ transplant (2), inflammatory bowel disease (2), and rheumatologic disorders (4). Phenotypically, the majority of patients were positive for gamma/delta (18/22), isochromosome 7q (8/13), and 4/9 (44%) tested positive for trisomy 8. Initial therapies included CHOP/CHOEP (14), ICE (2), EPOCH (1), pentostatin (1), and radiation (1). The median follow-up was 33 months (range 2,137). Progression free survival and overall survival (OS) were 9.5 months (95% CI; 1.8, 16.3) and 12 months (95% CI; 4.9, 18.5) respectively. 10/22 (45%) underwent splenectomy with one patient receiving splenectomy alone as treatment. 8/22 (36%) had stem cell transplant (SCT- 5 allogeneic and 3 autologous). Out of the 22 patients 4 (18%) were long-term survivors with 55, 74, 95, and 137 months; 3/4 had splenectomy at diagnosis and 2/4 had allogeneic SCT. The longest survivor had splenectomy only. Liver involvement was associated with worse OS; 10 months (95% CI; 1.6, 18) vs 35 months (95% CI; 4, NR), p = 0.036. Immune suppression at diagnosis was associated with worse OS; 5 months (95% CI; 1.3, 18) vs 18 months (95% CI; 9, 74), p = 0.036. A trend for better OS was seen with splenectomy and SCT. Conclusions: HSTL is a rare lymphoma with poor prognosis. Long-term survival was seen in 18% only. Liver involvement and immune suppression had a negative impact on OS. A larger cohort is needed to better evaluate the impact of different treatment options.