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Background Using an updated dataset with more patients and extended follow-up, we further established cancer patient characteristics associated with COVID-19 death. Methods Data on all cancer patients with a positive reverse transcription-polymerase chain reaction swab for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) at Guy’s Cancer Centre and King’s College Hospital between 29 February and 31 July 2020 was used. Cox proportional hazards regression was performed to identify which factors were associated with COVID-19 mortality. Results Three hundred and six SARS-CoV-2-positive cancer patients were included. Seventy-one had mild/moderate and 29% had severe COVID-19. Seventy-two patients died of COVID-19 (24%), of whom 35 died 2–5 years [2.81 (1.41–5.59)] or ≥5 years were associated with an increased mortality. Age >60 years and raised C-reactive protein (CRP) were also associated with COVID-19 death. Haematological cancer, a longer-established cancer diagnosis, dyspnoea at diagnosis and raised CRP were indicative of early COVID-19-related death in cancer patients ( Conclusions Findings further substantiate evidence for increased risk of COVID-19 mortality for male and Asian cancer patients, and those with haematological malignancies or a cancer diagnosis >2 years. These factors should be accounted for when making clinical decisions for cancer patients.

Apidaecin (Api), an unmodified 18-amino-acid-long proline-rich antibacterial peptide produced by bees, has been recently described as a specific inhibitor of translation termination. It invades the nascent peptide exit tunnel of the postrelease ribosome and traps the release factors preventing their recycling. Api binds in the exit tunnel in an extended conformation that matches the placement of a nascent polypeptide and establishes multiple contacts with ribosomal RNA (rRNA) and ribosomal proteins. Which of these interactions are critical for Api's activity is unknown. We addressed this problem by analyzing the activity of all possible single-amino-acid substitutions of the Api variants synthesized in the bacterial cell. By conditionally expressing the engineered api gene, we generated Api directly in the bacterial cytosol, thereby bypassing the need for importing the peptide from the medium. The endogenously expressed Api, as well as its N-terminally truncated mutants, retained the antibacterial properties and the mechanism of action of the native peptide. Taking advantage of the Api expression system and next-generation sequencing, we mapped in one experiment all the single-amino-acid substitutions that preserve or alleviate the on-target activity of the Api mutants. Analysis of the inactivating mutations made it possible to define the pharmacophore of Api involved in critical interactions with the ribosome, transfer RNA (tRNA), and release factors. We also identified the Api segment that tolerates a variety of amino acid substitutions; alterations in this segment could be used to improve the pharmacological properties of the antibacterial peptide.

Background It is widely accepted that advancing age is associated with worse COVID-19 outcomes. However, there is insufficient data analyzing the impact of COVID-19 in the older cancer population. The aim of the study is to establish if age has an influence on severity and mortality of COVID-19 in cancer patients. Methods We reviewed 306 oncology patients with PCR-confirmed COVID-19 from Guy’s Cancer Centre and its partner Trust King’s College Hospital, between 29 February – 31 July 2020. Demographic and tumor characteristics in relation to COVID-19 severity and death were assessed with logistic and Cox proportional hazards regression models, stratified by age (≤65 and >65 years). Severity of COVID-19 was classified by World Health Organization (WHO) grading. Results A total of 135 patients were aged ≤65 years (44%) and 171 aged >65 (56%). Severe COVID-19 presentation was seen in 27% of those aged ≤65 and 30% of those aged >65. The COVID-19 mortality rate was 19% in those aged ≤65 and 27% in those aged >65. In the older cohort, there was an increased incidence of severe disease in Caucasian ethnicity compared to the younger cohort (55% vs 43%) and compared to severe disease in Black and Asian ethnicities. There were increased co-morbidities in the older cohort including hypertension (54% vs 32%), diabetes (30% vs 12%) with increased rate of poly-pharmacy (62% vs 40%) compared to the younger cohort. In terms of cancer characteristics in the older cohort, there was a higher rate of patients with cancer for more than 2 years (53% vs 32%) and performance status of 3 (22% vs 6%). In terms of severity, Asian ethnicity [OR: 3.1 (95% CI: 0.88-10.96) p=0.64] had greater association with increasing COVID-19 severity in those aged >65. Interestingly, there were no positive associations between number of co-morbidities, treatment paradigm or performance status with severity of disease in the older group. The risk of mortality was greater in the elderly cohort with hematological cancer types [HR: 2.69 (1.31-5.53) p=0.85] and having cancer for more than 2 years [2.20 (1.09-4.42) p=0.28] compared to the younger cohort. Conclusions In our study we demonstrate that severity and mortality of COVID-19 did not significantly differ between the two age cohorts except in regards to Asian ethnicity, hematological malignancies and having cancer for more than 2 years. As expected, the older population had more co-morbidities and polypharmacy. Despite this, the incidence of severe COVID-19 was similar regardless of age. Further analyses for other geriatric presentations are ongoing to understand their interaction with COVID-19 in the cancer population. Citation Format: Rushan Sylva, Beth Russell, Charlotte Moss, Gincy George, Kieran Palmer, Vallari Shah, Thinzar Ko Ko, Tania Kalsi, Danielle Harari, Luigi De Michele, Shahram Kordasti, Danielle Crawley, Harriet Wylie, Fidelma Cahill, Anna Haire, Andrea D'Souza, Simon Gomberg, Austin Kulasekararaj, Mieke Van Hemelrijck, Saoirse Dolly. The impact of COVID-19 in the cancer population stratified by age: A real-world data study from Guy’s Cancer Center [abstract]. In: Proceedings of the AACR Virtual Meeting: COVID-19 and Cancer; 2021 Feb 3-5. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(6_Suppl):Abstract nr S11-03.

Severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2), emerged at the end of 2019 and caused an infection named COVID‐19 (Guan, Ni et al. 2020). Patients with compromised immune systems are at increased risk of complications but this risk is not precisely defined (Liang, Guan et al. 2020). Although age, gender, comorbidities and ethnicity are risk factors for adverse outcomes (Huang, Wang et al. 2020), various pre‐existing conditions, including haematological cancers, have also been reported to correlate with poor outcomes (Aries, Davies et al. 2020, He, Chen et al. 2020, Malard, Genthon et al. 2020, Martin‐Moro, Marquet et al. 2020, medRxiv 2020)

Introduction: Cancer patients have been considered a high-risk population in the COVID-19 pandemic. We previously investigated risk of COVID-19 death in COVID-19 positive cancer patients during a median follow-up of 134 days, and identified the following risk factors: male sex, age >60 years, Asian ethnicity, hematological cancer type, cancer diagnosis for >2.5 years, patients presenting with fever or dyspnea, and high levels of ferritin and C-reactive protein (CRP). Here, we further investigate which factors are associated with a COVID-19 related death within 7 days of diagnosis. Methods: Using data from Guy’s Cancer Centre and one of its partner trusts (King’s College Hospital), we included 306 cancer patients with a confirmed COVID-19 diagnosis (February 29th-July 31st 2020). 72 patients had a COVID-19 related death (24%) of whom 35 died within 7 days (50%). Cox proportional hazards regression was used to identify which factors were associated with a COVID-19 related death 24 months before COVID-19 diagnosis. Factors associated with COVID-19 related death 5 yrs since cancer diagnosis (HR: 4.41 (95%CI: 1.38-14.06)). Additionally, patients who presented with dyspnea had increased risk of COVID-19 related death Citation Format: Maria J. Monroy-Iglesias, Beth Russell, Charlotte Moss, Gincy George, Kieran Palmer, Sophie Papa, Sheeba Irshad, Paul Ross, James Spicer, Sharam Kordasti, Danielle Crawley, Harriet Wylie, Fidelma Cahill, Anna Haire, Rushan Sylva, Kamarul Zaki, Fareen Rahman, Ailsa Sita-Lumsden, Debra Josephs, Deborah Enting, Mary Lei, Sharmistha Ghosh, Claire Harrison, Angela Swampillai, Elinor Sawyer, Andrea D'Souza, Simon Gomberg, Paul Fields, David Wrench, Kavita Raj, Mary Gleeson, Kate Bailey, Richard Dillon, Matthew Streetly, Austin Kulasekararaj, Thinzar Ko Ko, Vallari Shah, Anne Rigg, Richard Sullivan, Mieke Van Hemelrijck, Saoirse Dolly. Clinical and demographic characteristics associated with shorter time to COVID-19 death [abstract]. In: Proceedings of the AACR Virtual Meeting: COVID-19 and Cancer; 2021 Feb 3-5. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(6_Suppl):Abstract nr S12-03.

Purpose To report a case of solitary plasmacytoma of the conjunctiva with corneal encroachment and to review the literature of all published cases. Methods A 70-year-old man presented with 1-month history of pain and watering in the right eye, 7 months after undergoing cataract surgery in the same eye. Results The mass was surgically excised. Pathology and immunohistochemistry were consistent with plasmacytoma. Staging studies found no evidence of systemic disease. Conclusions To our knowledge, this is the first case of plasmacytoma in the literature to involve the cornea. This case was not associated with systemic disease. Surgical excision and brachytherapy remain options for cases without corneal involvement.

Background: The Coronavirus disease 2019 (COVID-19) pandemic continues to have a significant impact on the treatment of cancer patients. Understanding the clinical course, potential risk factors for severe infection and excess mortality, is essential to improve patient outcomes. We previously presented preliminary results from 156 SARS-CoV-2 positive cancer patients from Guy’s Cancer Center, which suggested that increased COVID-19 mortality was associated with a diagnosis of cancer for over 2 years, Asian ethnicity and being on palliative treatment. Herein, we present an updated analysis using data from Guy’s Cancer Centre and a partner Hospital Trust (King’s College Hospital), with an increased number of patients and an extended follow up. Methods: We performed an analysis of all cancer patients who had a positive RT-PCR nasal/throat swab for SARS-CoV-2 infection at our Centers between 29th February and 31st July 2020. Associations between patients’ demographics, clinical characteristics, and laboratory investigations with COVID-19 severity and mortality, were assessed using Logistic regression and Cox proportional hazards models. Results: 306 SARS-CoV-2 positive cancer patients were included in the analysis with a median follow up of 134 days (IQR 32-156). 184 (60%) were male and 217 (71%) were aged over 60 (mean age: 66). The most common malignancies were haematological (38%) and urological-gynaecological (20%). 218 (71%) had mild/moderate COVID-19 and 88 (29%) had severe disease. The overall COVID-related mortality rate was 24%; 19% in solid and 32% in haematological cancers. Male sex [OR: 1.84 (95%CI:1.08-3.13)], Asian ethnicity [3.86 (1.20-12.36)], haematological cancer type [2.16 (1.18-3.95)], being diagnosed with cancer for 2-5 years [3.74 (1.80-7.78)] or ≥5 years [3.06 (1.50-6.26)] and a ferritin > 1964 mcg/l [54.92 (5.90-511.33)] were all associated with a risk of developing severe COVID-19 disease. Similarly, male sex [HR:1.97 (95%CI:1.15-3.38)], Asian ethnicity [3.42 (1. 59-7.35)], haematological cancer type [2.03 (1.16-3.56)] as well as a cancer diagnosis for >2-5 years [2.81 (1.41-5.59)] or ≥5 years [2.13 (1.06-4.27)] and a ferritin > 1964 mcg/l [16.11 (3.81-68.17)] were associated with an increased risk of death from COVID-19. Age >60 [2.14 (1.15-3.98)] and a raised CRP [4.10 (1.66-10.10)] were also associated with COVID-19 death. An inverse relationship was observed between a raised albumin and COVID-19 related death [0.12 (0.03-0.51)]. Performance status and treatment paradigm were not associated with COVID-19 severity or mortality. Conclusions: This study further substantiates the evidence for an increased risk of severe COVID-19 infection and mortality for male and Asian patients with cancer, and those with haematological malignancies or with a diagnosis of cancer for over 2 years. These risk factors should be taken into account when making clinical decisions for cancer patients during the pandemic. Citation Format: Kieran Palmer, Rushan Sylva, Beth Russell, Charlotte Moss, Vallari Shah, Thinzar Ko Ko, Gincy George, Shahram Kordasti, Danielle Crawley, Harriet Wylie, Fidelma Cahill, Anna Haire, Kamarul Zaki, Ailsa Sita-Lumsden, Debra Josephs, Deborah Enting, Angela Swampillai, Elinor Sawyer, Mary Lei, Andrea D’Souza, Simon Gomberg, Paul Fields, David Wrench, Richard Sullivan, Anne Rigg, Austin Kulasekararaj, Mieke Van Hemelrijck, Saoirse Dolly. Factors affecting COVID-19 outcomes in cancer patients from Guy’s Cancer Center and King's College Hospital [abstract]. In: Proceedings of the AACR Virtual Meeting: COVID-19 and Cancer; 2021 Feb 3-5. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(6_Suppl):Abstract nr P44.

Background High-risk myeloma patients have unsatisfactory outcomes with current treatments and are in urgent need of improved diagnostic and therapeutic strategies. We have recently validated specific markers predicting high-risk disease in newly diagnosed MM (NDMM), in particular double-hit with presence of ≥2 consensus high-risk markers t(4;14), t(14;16), t(14;20), del(1p), gain(1q), del(17p) (Shah V, et al., Leukemia 2018) and diagnostic GEP SKY92 high risk signature (Sherborne A, et al., IMW 2017). Diagnostic tests for these markers were implemented in the UK multi-center OPTIMUM: MUK9 trial to prospectively stratify therapy for high-risk NDMM. Trial design OPTIMUM: MUK9 is a phase 2 trial for transplant eligible NDMM, consisting of two inter-related protocols: a molecular screening protocol (MUK9A) and an interventional trial (MUK9B) for high-risk MM identified in MUK9A. Patients with suspected or confirmed MM fit for intensive therapy enrolled in MUK9A have central molecular profiling at ICR, London, of CD138-selected BM MM cells for translocations, copy number aberrations (qRT-PCR; MLPA P425, MRC Holland) and SKY92 signature status (MMprofiler; SkylineDx). If clinically indicated SOC therapy (VTD, max. 2 cycles) can be given whilst central results are generated. Patients found to have high-risk MM by double-hit and/or SKY92 are offered enrolment into MUK9B. All other patients receive SOC (VTD, HD-MEL+ASCT) for which clinical data is collected. Patients diagnosed with plasma cell leukemia (PCL) can be enrolled directly in MUK9B. MUK9B treatment consists of quintuplet daratumumab, cyclophosphamide, bortezomib, lenalidomide, dexamethasone (Dara-CVRd) induction (up to 6 cycles), bortezomib-augmented single HD-MEL+ASCT, Dara-VRd consolidation 1 (6 cycles), Dara-VR consolidation 2 (12 cycles) and Dara-R maintenance (until PD). Dose adjustments are permitted in order to maximize tolerability of long-term therapy. Patient reported outcomes (PRO) are recorded at baseline and throughout treatment. Response and MRD are centrally assessed (Birmingham, Leeds). Primary endpoint for MUK9A is feasibility of central molecular testing within 56 days turnaround time, which we report on here. Primary endpoint of MUK9B is treatment efficacy, comparing MUK9B PFS to near-concurrent molecularly matched high-risk patient outcomes from UK NCRI Myeloma XI using a Bayesian design. Secondary endpoints include safety, PFS2, MRD and OS and study of molecular evolution in high-risk disease. Results The protocol recruited 29/Sep/17 - 31/Jul/19 at 39 UK sites, achieving the recruitment target of 105 high-risk patients treated on MUK9B ahead of projections. At the time of analysis (12/Jul/19), 430 patients with suspected or confirmed NDMM have been recruited to MUK9A across 39 UK NHS hospitals. Of these, 376 (87%) patients were confirmed to have symptomatic MM (60.9% male; median age 61y (range 29-79)) as per updated IMWG diagnostic criteria (2014), including 9 (2%) PCL patients, with the remainder diagnosed as SMM/MGUS (31; 7%) or other (14; 3%). For 371 of the 376 symptomatic MM patients BM was received by the central laboratory and was of sufficient quality for profiling in 331 (89%) patients. Repeat samples were requested for all others and a sufficient sample received for 20/45 (44%). Central results were successfully reported within the pre-specified 56 day interval for all patients (median 17 days; IQR 13-22). Of 346 patients with a reported result, 128 (37.0%) have high-risk MM, with molecular characteristics mirroring Myeloma XI patients (Figure 1). PCL patients show expected characteristics as listed in Table 1. Basic demographics were not different between high-risk vs. non-high-risk. 101 high-risk patients have or are planning to enter MUK9B, 10 pending decision; 17 high-risk patients did not enter MUK9B, the majority due to ineligibility. 92 patients have started Dara-CVRD therapy. There are currently no safety concerns, the majority of patients are completing induction successfully; 1 patient stopped induction therapy due to adverse events. Updated results will be presented. Discussion Our data demonstrate feasibility of multi-center molecular stratified trial delivery for high-risk NDMM patients. These early trial results strongly support accelerated trial strategies for MM patient groups with high unmet need and rational drug development specifically for high-risk MM. Disclosures Jenner: Abbvie, Amgen, Celgene, Novartis, Janssen, Sanofi Genzyme, Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Hall:Celgene, Amgen, Janssen, Karyopharm: Other: Research funding to Institution. Walker:Janssen, Celgene: Other: Research funding to Institution. Croft:Celgene: Other: Travel expenses. Jackson:Celgene, Amgen, Roche, Janssen, Sanofi: Honoraria. Flanagan:Amgen, Celgene, Janssen, Karyopharm: Other: Research funding to Institution. Drayson:Abingdon Health: Consultancy, Equity Ownership. Owen:Celgene, Janssen: Consultancy; Celgene: Research Funding; Janssen: Other: Travel expenses; Celgene, Janssen: Honoraria. Pratt:Binding Site, Amgen, Takeda, Janssen, Gilead: Consultancy, Honoraria, Other: Travel support. Cook:Celgene, Janssen-Cilag, Takeda: Honoraria, Research Funding; Janssen, Takeda, Sanofi, Karyopharm, Celgene: Consultancy, Honoraria, Speakers Bureau; Amgen, Bristol-Myers Squib, GlycoMimetics, Seattle Genetics, Sanofi: Honoraria. Brown:Amgen, Celgene, Janssen, Karyopharm: Other: Research funding to Institution. Kaiser:Celgene, Janssen: Research Funding; Abbvie, Celgene, Takeda, Janssen, Amgen, Abbvie, Karyopharm: Consultancy; Takeda, Janssen, Celgene, Amgen: Honoraria, Other: Travel Expenses.

Pancreaticoduodenectomy is the standard treatment for localised neoplasms of the pancreatic head. The operation can be performed safely in specialist units but good outcome is compromised if postoperative blood flow to the liver and biliary tree is inadequate. Coeliac artery occlusion with blood supply to the liver arising from the superior mesenteric artery via the gastroduodenal artery is difficult to recognise, especially intraoperatively. Recognition of absent hepatic artery pulsation after occlusion of the gastroduodenal artery opens a dilemma: should the resection be abandoned or should vascular reconstruction be undertaken, adding risk to an already complex procedure? We describe two cases with a resectable pancreatic endocrine tumour in which coeliac artery occlusion caused by median arcuate ligament compression was identified from cross-sectional imaging and reconstructions. We highlight two different strategies to correct the vascular insufficiency and allow safe pancreatic resection.

Background Mutations of RAF/RAS genes are one of the most common oncogenic events in multiple myeloma. Therapeutic targeting of RAF/RAS/MAPK signalling using small molecule inhibitors has led to significant responses in solid cancers. Recently, combined inhibition of key pathway kinases has demonstrated increased efficacy and decrease toxicity, leading to development of second-generation small molecules with dual inhibitory function. RO5126766 is a potent dual RAF-MEK inhibitor that has demonstrated significant clinical activity with minor toxicities in various solid cancers carrying RAS mutations in a currently ongoing phase I basket study (Trial number NCT204007509; Chenard-Poirier et al. ASCO 2017). Based on the drug's promising efficacy, the trial has been expanded to include myeloma patients with RAF/RAS tumour mutations to provide information on safety and preliminary efficacy in this patient population. We report updated results for RAF/RAS-mutant relapsed and refractory MM patients treated with RO5126766. Methods MM patients with relapsed or relapsed and refractory myeloma whose disease had progressed after at least 3 prior therapies were recruited to the study. All patients had been treated with an IMiD and a proteasome inhibitor and their tumours were confirmed to carry a RAS mutation by sequencing. Patients were treated with RO5126766 4mg twice weekly for 3 out of 4 weeks, in 28 day cycles, with the addition of optional weekly dexamethasone as per investigator's discretion. Response assessment was completed using IMWG criteria and toxicities were reported according to CTCAE version 4.0. Whole body diffusion-weighted MRI every 3 cycles was used for functional imaging disease assessment. Results At the time of analysis, a total of five patients were recruited; one was still receiving cycle 1 of therapy, with the four remaining patients being evaluable at the point of abstract submission. The median age of evaluable patients at initiation of treatment was 74 years (range 70-76). Patients had received median 4 (range 3-5) lines of prior therapy, including autologous stem cell transplant (75%). Three tumours had a KRAS mutation whilst in one tumour, synchronous KRAS and NRAS mutations were found. Three patients received RO5126766 alone, while 1 patient also received weekly concomitant dexamethasone. One patient (KRAS and NRAS mutations) achieved a partial response after 1 cycle of therapy but progressed after 7 months. A second patient achieved stable disease (confirmed biochemically and by functional MRI imaging) with single agent RO5126766 treatment and currently continues on trial having completed 8 cycles of therapy. The two remaining patients progressed after 2 and 1.5 cycles, with the latter patient receiving dexamethasone in combination with RO5126766. The two patients who received 7 and 8 cycles of RO5126766 experienced no clinically significant adverse events (AE), with commonly reported toxicities including grade 1 rash (2/2), grade 1 diarrhoea and grade 1 thrombocytopenia. This is in line with tolerability profile observed in the solid tumour cohorts (n=28 solid tumour patients recruited to date) of this basket trial. One patient developed worsening kidney impairment attributable to disease progression with rising serum free light chains and came off study. Interestingly, ocular toxicities, commonly associated with RAF-MEK inhibitors, were not observed in this patient cohort, which may be related to their dosing schedule. Conclusion In this basket study across RAS mutated tumours, the novel, dual RAF-MEK inhibitor RO5126766 as monotherapy in myeloma patients has shown promising single agent activity. In line with observations in the in parallel recruiting solid tumour cohorts, the dual RAF-MEK inhibitor RO5126766 is generally well tolerated and can be administered as an ongoing therapy. This has been observed in a solid tumour patient who has been receiving RO5126766 for 3.5 years with little and manageable toxicities. Longitudinal patient bone marrow trephine material has been collected and analysis of phospho-protein markers of RAS/MAPK pathway activation for PD biomarker evaluation will be performed. Recruitment to this study continues and data will be updated prior to the conference. Potential single-agent activity of RO5126766 with manageable toxicity grants further evaluation of its use as a molecularly targeted therapy in myeloma. Disclosures Sriskandarajah: Celgene: Other: Travel, Accommodation expenses, Speakers Bureau. Boyd:Celgene: Consultancy, Honoraria, Other: Advisory role; Janssen: Honoraria, Other: Travel and Accommodation expenses; Novartis: Consultancy, Honoraria. Shah:Sanofi: Other: Travel and Accommodation expenses; Celgene: Other: Travel, Accommodation expenses. Hall:Sanofi (Inst): Research Funding; Cambridge Major Laboratories (Inst): Research Funding; Accuray (Inst): Research Funding; Kyowa Hakko Karin (Inst): Research Funding; Astrazeneca (Inst): Research Funding; Bayer (Inst): Research Funding. Tunariu:Janssen: Speakers Bureau; Sanofi: Speakers Bureau. de Bono:Sanofi (Inst): Research Funding; AstraZeneca (Inst): Research Funding; GlaxoSmithKline: Other: Travel, Accomodation expenses; AstraZeneca: Consultancy, Honoraria, Other; Astellas Pharma: Consultancy, Honoraria, Other: Travel, Accommodation expenses; Sanofi: Consultancy, Honoraria, Other: Travel, Accommodation expenses; Genentech/Roche: Consultancy, Honoraria, Research Funding; Pfizer: Honoraria; Orion Pharma GmBH: Other: Travel, Accommodation expenses; Qiagen: Other: Travel, Accommodation expenses; Taiho Pharmaceutical: Other: Travel, Accommodation expenses; Vertex: Other: Travel, Accommodation expenses; Genentech (Inst): Research Funding; Abiraterone Rewards to Investors (Inst): Patents & Royalties: Abiraterone; PARP inhibitors and DNA repair defects (Inst): Patents & Royalties: PARP inhibitors; Genmab: Other: Travel, Accommodation expenses. Banerji:Institute of Cancer research: Employment; Novartis: Consultancy; Onyx (Inst): Research Funding; Chugai Pharma (Inst): Research Funding; AstraZenca (Inst): Research Funding; Astex Pharmaceuticals: Consultancy. Kaiser:Janssen: Consultancy, Honoraria; Takeda: Consultancy, Other: Travel Support; Bristol-Myers Squibb: Consultancy, Other: Travel support; Chugai: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding.

INTRODUCTION Features of high risk myeloma (MM) have been studied in detail but patients with longer term responses to first-line therapy are less well characterised. Identification of common features of this group may support optimised management. Here we analysed clinical and genetic characteristics of long-term responders of 4,249 trial patients from the UK MRC Myeloma IX (M-IX) and NCRI Myeloma XI (M-XI) trials. PATIENTS AND METHODS In M-IX patients were randomised between alkylating therapy (CVAD or MP) and thalidomide-based induction therapy (CTD). M-XI patients were randomised between thalidomide and lenalidomide based induction (CTD vs CRD) and a response-based bortezomib (CVD) intensification. Fitter patients received HD-Mel+ASCT consolidation. Patients were then randomised to thalidomide (M-IX) or lenalidomide (M-XI) maintenance or observation. Trials included symptomatic, newly diagnosed patients based on CRAB criteria. This analysis included 1,921 My-IX and 2,328 My-XI patients with median follow-up of 73 and 61 months (m), respectively. Genetic profiling was available for 1,866 patients. Patients with a long-term response post induction (PFS≥48m) were identified and their baseline characteristics, responses and treatment compared to those with PFS RESULTS In M-IX, 283 (25.8%) of transplant-eligible (TE) patients had PFS ≥48m whereas 58 (7%) of transplant non-eligible (TNE) patients reached PFS≥48m. In M-XI 410 (34.2%) patients had PFS≥48m for TE and 116 (10.2%) for TNE. Extended progression free survival translated to overall survival (OS) benefit with a median post progression OS of 36.9m for PFS≥48m vs 16.7m for PFS Clinical factors including ISS I (P The proportion of patients with a high risk lesion (Adverse translocation, Gain(1q) or Del(17p)) were lower in the PFS≥48m group than The majority of patients with PFS ≥48m showed ≥VGPR after induction +/- consolidation: 211 (76.4%) and 340 (84%) of PFS ≥48m patients in the TE arms and 26 (49.1%) and 87 (76.3%) in the TNE arms of M-IX and M-XI, respectively. 86.7% of patients who achieved a ≥VGPR had a PFS ≥48m in the absence of high risk lesions compared to 72.8% with any high risk lesion present (P=0.004). Some patients with PFS≥48m had only reached PR after induction; 56 (20.3%) and 57 (14.1%) of PFS ≥48m patients in the TE arm and 15 (28.3%) and 24 (21.1%) in the TNE arms of M-IX and M-XI, respectively. Baseline factors that were associated with still being able to achieve PFS≥48m from induction after only achieving a PR included the lack of high risk genetic lesions (P CONCLUSIONS Response assessment after induction+/-HD-Mel consolidation with baseline factors can define a patient group with superior outcomes in both TE and TNE patients and may influence future treatment strategies of MM patients undergoing first line therapy. Further analyses including modelling of predictors of response duration are ongoing and will be presented at the conference. Disclosures Shah: Celgene: Other: Travel, Accommodation expenses; Sanofi: Other: Travel and Accommodation expenses. Striha:Janssen: Research Funding; Abbvie: Research Funding; Celgene: Research Funding; MSD: Research Funding; Amgen: Research Funding. Hockaday:Celgene: Research Funding; Amgen: Research Funding; Abbvie: Research Funding; Janssen: Research Funding; MSD: Research Funding; Millenium: Research Funding. Pawlyn:Celgene Corporation: Consultancy, Honoraria, Other: Travel support; Amgen: Consultancy, Honoraria, Other: Travel Support; Janssen: Honoraria, Other: Travel support; Takeda Oncology: Consultancy, Other: Travel support. Jenner:Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Drayson:Abingdon Health: Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Owen:Celgene: Consultancy, Honoraria, Research Funding; Takeda: Honoraria, Other: Travel Support; Janssen: Consultancy, Other: Travel Support. Gregory:Celgene: Consultancy, Honoraria, Research Funding; Merck Sharp and Dohme: Research Funding; Janssen: Honoraria; Amgen: Research Funding. Morgan:Janssen: Research Funding; Takeda: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding. Davies:Janssen: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Takeda: Consultancy, Honoraria. Cook:Janssen: Consultancy, Honoraria, Research Funding, Speakers Bureau; Seattle Genetics: Honoraria; Glycomimetics: Consultancy, Honoraria; Takeda: Consultancy, Honoraria, Research Funding, Speakers Bureau; Amgen: Consultancy, Honoraria, Research Funding, Speakers Bureau; Janssen: Consultancy, Honoraria, Research Funding, Speakers Bureau; Sanofi: Consultancy, Honoraria, Speakers Bureau; Bristol-Myers Squibb: Consultancy, Honoraria; Celgene Corporation: Consultancy, Honoraria, Research Funding, Speakers Bureau. Cairns:Celgene: Research Funding; Amgen: Research Funding; Merck Sharp and Dohme: Research Funding. Jackson:Roche: Consultancy, Honoraria, Speakers Bureau; Merck Sharp and Dohme: Consultancy, Honoraria, Speakers Bureau; Amgen: Consultancy, Honoraria, Speakers Bureau; Celgene: Consultancy, Honoraria, Other: Travel Support, Research Funding, Speakers Bureau; Takeda: Consultancy, Honoraria, Other: Travel Support, Research Funding, Speakers Bureau. Kaiser:Amgen: Consultancy, Honoraria; Takeda: Consultancy, Other: travel support; Janssen: Consultancy, Honoraria; Chugai: Consultancy; Bristol-Myers Squibb: Consultancy, Other: travel support; Celgene: Consultancy, Honoraria, Research Funding.

SummaryTherapeutic antibodies have transformed cancer therapy, unlocking mechanisms of action by engaging the immune system. Unfortunately, cures rarely occur and patients display intrinsic or acquired resistance. Here, we demonstrate the therapeutic potential of targeting human (h) FcγRIIB (CD32B), a receptor implicated in immune cell desensitization and tumor cell resistance. FcγRIIB-blocking antibodies prevented internalization of the CD20-specific antibody rituximab, thereby maximizing cell surface accessibility and immune effector cell mediated antitumor activity. In hFcγRIIB-transgenic (Tg) mice, FcγRIIB-blocking antibodies effectively deleted target cells in combination with rituximab, and other therapeutic antibodies, from resistance-prone stromal compartments. Similar efficacy was seen in primary human tumor xenografts, including with cells from patients with relapsed/refractory disease. These data support the further development of hFcγRIIB antibodies for clinical assessment.

A major feature that distinguishes type I from type II anti-CD20 monoclonal antibodies (mAbs) and reduces their therapeutic efficacy is the tendency to internalize from the cell surface. We have shown previously that the extent of internalization correlates with the capacity of type I mAb to simultaneously engage both CD20 and the inhibitory Fcγ receptor, FcγRIIb, in a bipolar configuration. Here, we investigated whether mAbs directed at other B-cell surface receptors also engaged FcγRIIb and whether this interaction promoted internalization. Most mAbs engaged and activated FcγRIIb, with the strength of activation related to the level of mAb bound to the cell surface. However, engagement did not affect internalization of most mAb-ligated receptors, either in cell lines or primary chronic lymphocytic leukemia cells with the exception of CD19 and CD38. Furthermore, at high cell concentrations/density both cis and trans interactions between cell-surface bound mAb and FcγRIIb were evident, but trans interactions did not inhibit type I anti-CD20 mAb-mediated internalization. These data identify that FcγRIIb is engaged by many mAbs in both cis and trans configurations, triggering its activation, but that internalization via FcγRIIb occurs for only a select subset. These findings have implications when designing new antibody-based therapeutics.

The anti-CD20 monoclonal antibody, rituximab, has improved treatment outcomes in B-cell malignancies. However, several B-cell lymphomas either do not respond to rituximab or develop resistance. Internalisation of rituximab may be partly responsible for this resistance. We recently showed that the level of the inhibitory Fc receptor (CD32B) at the cell surface controls the rate of rituximab internalisation. However, the precise mechanism involved has not been elucidated. Different isoforms of CD32B exist (B1 and B2), only one of which (B2) has previously been associated with an ability to internalise after engagement of immune complexes. The B1 form in contrast contains an additional intracellular region that makes it more resistant to internalisation. We therefore investigated the role of the two different CD32B isoforms (B1 and B2) and the associated intracellular tail on rituximab internalisation. CD32B1 and CD32B2 isoforms were stably transfected into CD32B-ve mouse IIA1.6 and human Ramos lymphoma cells, and flow cytometry was then used to determine the relative rates of CD32B and CD20 internalisation. Additionally, we generated mutant versions of the CD32B receptors, including those lacking the entire cytoplasmic domain to assess the importance of intracellular signalling. In contrast to expectations both B1 and B2 CD32B isoforms were downregulated upon engagement with CD32B mAb as a surrogate for immune complexes, although in agreement with earlier reports the CD32B2 isoform internalised more extensively. However, the rate of rituximab internalisation occurred equally with both isoforms and was dependent on relative expression of CD32B and the CD20:CD32B ratio at the cell surface rather than any specific activity imparted by the CD32 intracellular domain. These studies suggest that the intracellular part of CD32B is redundant for rituximab-induced CD20 internalisation and imply that internalisation is augmented by CD32B through its physical ability to bind the Fc region of rituximab at the cell surface. Disclosure All authors have declared no conflicts of interest.