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Bendamustine and rituximab (BR) therapy is commonly used in the treatment of Waldenström Macroglobulinemia (WM). The impact dose of Bendamustine dose on response and survival outcomes is not well-established, and the impact of its use in different treatment settings is not clear. We aimed to report response rates and survival outcomes following BR, and clarify the impact of depth of response and bendamustine dose on survival. A total of 250 WM patients treated with BR in the frontline or relapsed settings were included in this multicenter, retrospective cohort analysis. Rates of partial response (PR) or better differed significantly between the frontline and relapsed cohorts (91.4% vs 73.9%, respectively; p < 0.001). Depth of response impacted survival outcomes: two-year predicted PFS rates after achieving CR/VGPR vs PR were 96% versus 82%, respectively (p = 0.002). Total bendamustine dose was predictive of PFS: in the frontline setting, PFS was superior in the group receiving ≥1000 mg/m2 compared with those receiving 800–999 mg/m2 (p = 0.04). In the relapsed cohort, those who received doses of

The benefits of non-myeloablative stem cell transplant in older patients with acute myeloid leukaemia are unclear. We compare the long-term outcomes of this regimen in those aged 55-65 years in first remission with a chemotherapy only cohort that achieved durable morphologic remission. Five-year overall survival was similar (32% vs 33%, P = 0.90), as was relapse-free survival (23% vs 20%, P = 0.37). There was a trend for decreased relapse that was balanced against increased non-relapse mortality with transplantation.

Introduction Brentuximab vedotin (BV)-CHP is the new standard regimen for first-line treatment of systemic anaplastic large cell lymphoma (sALCL). We undertook a retrospective analysis of consecutive patients diagnosed with sALCL, treated in routine practice, to serve as a benchmark analysis for comparison BV-CHP efficacy in routine practice. Methods Patients aged 16 years or older with sALCL treated in seven UK and Australian centres and from 14 additional centres from the UK Haematological Malignancy Research Network database (n = 214). Treatment allocation was clinician choice and included best supportive care (BSC). Main outcomes were time to treatment failure (TTF) and overall survival (OS). Multivariable analysis for predictors of both TTF and OS was also undertaken. Results The median age 52 years (range 16–93), 18% ECOG ≥ 3 and 40% of cases were ALK positive. CHOP (cyclophosphamide, adriamycin, vincristine, prednisolone) was employed in 152 (71%) of patients and CHOEP (CHOP + etoposide) in 4% of patients. For CHOP-treated patients overall response rate (ORR) was 65% and complete response (CR) 47%. Only 9% of patients underwent autologous stem cell transplant (ASCT). With 57 months median follow-up, 4-year TTF and OS were 41.2% (95% CI 33.1–49.1) and 58.9% (95% CI 50.3–66.5) respectively. Multivariable analysis showed ALK+ status was independently associated with superior TTF (HR 0.36, 95% CI 0.21–0.63) but not OS (0.44, 95% CI 0.18–1.07). Discussion We present a retrospective analysis with mature follow-up of one of the largest multicentre populations of sALCL available, comparable to similar large retrospective studies. ALK status remains a strong predictor of outcomes. Conclusion These data serve as a robust benchmark for BV-CHP as the new standard of care for sALCL. Similar real-world evidence with BV-CHP will be desirable to confirm the findings of ECHELON-2. Supplementary Information The online version contains supplementary material available at 10.1007/s12325-021-01764-0.

Primary and secondary central nervous system lymphomas (PCNSL/SCNSL) are aggressive rare malignancies with dismal outcomes. Encouraging data have emerged from Phase I/II clinical trials treating relapsed/refractory PCNSL/SCNSL with ibrutinib. We analysed 33 patients who received ibrutinib, alone or with other therapies, for PCNSL (n = 9) or SCNSL (n = 24). The objective response rate was 58% (complete response 55%). The median progression-free survival and overall survival for patients with PCNSL were both 3·1 months; for SCNSL, 10·2 and 11·5 months respectively. Only one invasive fungal infection was observed, despite concurrent or recent use of dexamethasone 8-16 mg daily in 14 patients (42%). Ibrutinib has encouraging activity in these aggressive malignancies.

Prophylactic high-dose methotrexate (HD-MTX) is often used for diffuse large B-cell lymphoma (DLBCL) patients at high risk of central nervous system (CNS) relapse, despite limited evidence demonstrating efficacy or the optimal delivery method. We conducted a retrospective, international analysis of 1384 patients receiving HD-MTX CNS prophylaxis either intercalated (i-HD-MTX) (n = 749) or at the end (n = 635) of R-CHOP/R-CHOP-like therapy (EOT). There were 78 CNS relapses (3-year rate 5.7%), with no difference between i-HD-MTX and EOT: 5.7% vs 5.8%, P = .98; 3-year difference: 0.04% (−2.0% to 3.1%). Conclusions were unchanged on adjusting for baseline prognostic factors or on 6-month landmark analysis (n = 1253). In patients with a high CNS international prognostic index (n = 600), the 3-year CNS relapse rate was 9.1%, with no difference between i-HD-MTX and EOT. On multivariable analysis, increasing age and renal/adrenal involvement were the only independent risk factors for CNS relapse. Concurrent intrathecal prophylaxis was not associated with a reduction in CNS relapse. R-CHOP delays of ≥7 days were significantly increased with i-HD-MTX vs EOT, with 308 of 1573 (19.6%) i-HD-MTX treatments resulting in a delay to subsequent R-CHOP (median 8 days). Increased risk of delay occurred in older patients when delivery was later than day 10 in the R-CHOP cycle. In summary, we found no evidence that EOT delivery increases CNS relapse risk vs i-HD-MTX. Findings in high-risk subgroups were unchanged. Rates of CNS relapse in this HD-MTX-treated cohort were similar to comparable cohorts receiving infrequent CNS prophylaxis. If HD-MTX is still considered for certain high-risk patients, delivery could be deferred until R-CHOP completion.

TPS7587 Background: Follicular lymphoma (FL) is the commonest indolent lymphoma, comprising 20% of non-Hodgkin Lymphoma, with approximately 80% of patients (pts) requiring therapy. At present, advanced stage is incurable; most pts require >1 treatment. Overall response rates (ORR) to standard chemoimmunotherapy (bendamustine or CHOP with rituximab or obinutuzumab) approximate 85% with considerable toxicity (grade 3-5 in 69-75%) (Hiddemann 2018). With the FL population predominantly >65 years, 10-year median survival and need for further therapy, efficacious treatments with low toxicity are desirable. PD1/PDL1 axis inhibitors are active in FL. A phase I study of obinutuzumab (O) + atezolizumab (A) induced 57% ORR in pts with rituximab-refractory FL (Palomba 2017). Our phase II ‘1st FLOR’ study, combining nivolumab + rituximab in treatment naïve FL yielded 92% ORR, (54% Complete Response, CR). Toxicity profiles compared favourably with conventional chemotherapy: 41% grade 3-5 events (Hawkes 2021). FL is sensitive to low dose radiotherapy (RT), with abscopal effects reported, and potential to improve treatment efficacy with minimal additional toxicity when combined with PD1/PDL1 inhibitors (Sharabi 2015). This investigator initiated, multicentre single-arm phase II PET-adapted trial aims to assess the response of O + A +/- RT for treatment-naïve FL, reducing treatment-related toxicity using a chemotherapy-free, multi-modality, synergistic regimen. Methods: Eligible pts are >18 years, ECOG 0-2 with untreated, biopsy proven, grade 1-3A stage II-IV FL. Exclusions are significant compressive symptoms, autoimmune disease, pneumonitis and treatment urgency. All pts receive 6 cycles (q21 days) of O 1000mg + A 1200mg (plus O given on days 8 & 15 of cycle 1). Interim PET-CT is performed post cycle 2. Pts with less than CR will undergo RT (4Gy) to residual disease after cycle 3. At end of induction, responding patients will receive maintenance O (up to 12 cycles, 1000mg Q8W). Pts with significant progression will be taken off study. Total follow-up is 2 years post treatment. Primary endpoint is CR rate following 6 x O&A +/- RT. Secondary endpoints include ORR, PFS, OS and adverse events. PET centres are ARTnet accredited with central analysis. An extensive exploratory biomarker substudy is planned. Sample size is 46 according to a Simon’s 2-stage design. If ≥5 positive responses (CR +/- PR) without prohibitive toxicity are seen in the first 15 pts, 31 further pts will be recruited.The trial has currently enrolled 7 pts from 4 Australian sites. Clinical trial information: NCT04962126.

Myeloproliferative neoplasms are characterised by somatic mutations in pathways that regulate cell proliferation, epigenetic modifications, RNA splicing or DNA repair. Assessment of the mutational profile assists diagnosis and classification, but also aids assessment of prognosis, and may guide the use of emerging targeted therapies. The most practical way to provide information on numerous genetic variants is by using massively parallel sequencing, commonly in the form of disease specific next generation sequencing (NGS) panels. This review summarises the diagnostic and prognostic value of somatic mutation testing in Philadelphia-negative myeloproliferative neoplasms: polycythaemia vera, essential thrombocythaemia, primary myelofibrosis, chronic neutrophilic leukaemia, systemic mastocytosis, and chronic eosinophilic leukaemia. NGS panel testing is increasing in routine practice and promises to improve the accuracy and efficiency of pathological diagnosis and prognosis. Refereed/Peer-reviewed

Introduction: Central nervous system (CNS) relapse in diffuse large B-cell lymphoma (DLBCL) is uncommon but is associated with poor outcomes. In selected high risk patients (pts), high dose methotrexate (HDMTX) is often used as CNS prophylaxis with frontline (1L) DLBCL therapy despite uncertain efficacy, optimum dose and timing of delivery. A recent UK study (Wilson et al 2020) showed that intercalated HDMTX (i-HDMTX) was associated with increased toxicity and R-CHOP delays compared to end of treatment (EOT) delivery. Although hypothesis generating, the study size was insufficient to determine whether EOT was non-inferior in terms of CNS relapse risk. Methods: We conducted an international, multicentre retrospective analysis of consecutive DLBCL or high grade BCL pts between 2007-20 from 47 centers in Europe, Australia and N. America. Pts were included if they received R-CHOP or R-CHOP-like 1L therapy with curative intent as well as HDMTX CNS prophylaxis (≥1 cycle). Concurrent intrathecal (IT) prophylaxis was permitted. Pts with known CNS involvement at baseline and those treated with more intensive protocols (e.g. R-DA-EPOCH) were excluded. i-HDMTX was defined as any pt receiving a HD-MTX cycle before the final R-CHOP cycle. CNS relapse events were excluded if occurring after first systemic lymphoma relapse/progression. Time to event endpoints were measured from diagnosis to first event or censor and analysed using Kaplan-Meier and Cox regression methods. Time to CNS relapse was analysed using competing risk Fine and Gray method (for death and non-synchronous systemic relapse). To mitigate for possible immortality bias in the EOT arm, a landmark analysis for pts alive and free from progression at 6 months was conducted. We aimed to exclude a 5% difference in 2-year (y) CNS relapse rates. Results: 1,384 pts were analysed. 750 received i-HDMTX and 634 received EOT HDMTX. Key baseline characteristics are summarised in Table 1. Median follow up was 37.9 months. 44.2% had high CNS IPI (4-6) with no significant difference between i-HDMTX and EOT groups (45.1% vs 43.1%, p=0.087). ≥2 cycles of HDMTX were used in 86.6% with no difference between groups (85.6% vs 87.9%, p=0.22). Concurrent IT prophylaxis use was higher for EOT pts (55.6% vs 38.1% p 78 CNS relapses (42 i-HDMTX, 36 EOT) were observed: parenchymal in 41 (53%), parenchymal and leptomeningeal in 16 (21%) and isolated leptomeningeal in 21 (27%). There was no significant difference in 2y CNS relapse rates between i-HDMTX and EOT in all pts: 5.2% vs 3.9%, adjusted hazard ratio (HR) 0.92 (95% CI 0.58-1.47), p=0.74, 2y difference -0.2% (-2.0-2.5) or landmark analysis: 2.8% vs 4.1%, HR: 0.93 (0.56-1.55), p=0.79, 2y difference: -0.3% (-1.8-2.2%) (Fig 1a/b). Exploratory analyses focusing on pts with isolated CNS relapse (n=57) demonstrated similar results (2y rates 3.6% vs 3.0%, p=0.99). On multivariable analysis (MVA) of risk factors for CNS relapse, renal/adrenal involvement was the only variable associated with increased CNS relapse risk (adjusted HR 1.74 (1.03-2.92), p=0.038). Notably, IT prophylaxis was not associated with reduction in CNS relapse. In 600 high CNS IPI (4-6) pts, there was no difference in CNS relapse risk between i-HD-MTX and EOT (3y rates 9.4% vs 8.6%, HR 0.92 (95% CI 0.52-1.62)). In a composite high risk group including CNS IPI 4-6 and/or any of the following: ≥3 extranodal sites, renal, adrenal, testicular or breast involvement (n=885) there was no difference in 3y CNS relapse rates between groups (i-HDMTX 7.6% vs EOT 7.4%, HR 0.94 (0.58-1.53)). Progression-free survival (PFS) and overall survival (OS) in the i-HDMTX and EOT groups were as follows: 3y PFS 70.7% vs 76.7% (p=0.098), 3y OS 79.9% vs 87.0% (p=0.0016). However, there were no PFS/OS differences between groups on landmark analysis (n=1259) (Fig 1c). On analysis of pts experiencing ≥1 R-CHOP delay of ≥7 days, use of i-HDMTX was the only factor on MVA associated with increased delays (p Discussion: We found no evidence that EOT delivery increases CNS relapse risk when compared to i-HDMTX in this large analysis of pts treated with 1L R-CHOP. Delays to R-CHOP cycles were increased with i-HDMTX. Findings in a high risk subgroup were unchanged and rates of CNS relapse in this HDMTX treated group were similar to published comparable high risk cohorts receiving infrequent CNS prophylaxis. Where HDMTX prophylaxis is used, delivery could be deferred until R-CHOP completion. Figure 1 Figure 1. Disclosures Wilson: Takeda: Other: Conference fees; Janssen: Other: Conference fees; Abbvie: Honoraria. Eyre: Janssen: Honoraria; Secura Bio: Consultancy, Honoraria; Gilead/KITE: Honoraria, Other: Travel support for conferences, Research Funding, Speakers Bureau; Roche: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria, Other: Travel to conferences; AstraZeneca: Honoraria, Research Funding; Loxo Oncology: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Incyte: Consultancy; Beigene: Honoraria, Research Funding. Ahearne: Pfizer: Research Funding; Takeda: Honoraria; Roche: Honoraria. Schorb: Roche: Research Funding; Riemser Pharma GmbH: Honoraria, Research Funding; AbbVie: Research Funding. Ku: Antegene: Consultancy; Roche: Consultancy; Genor Biopharma: Consultancy. Narkhede: Genentech/Roche: Research Funding; Gilead: Research Funding; Genmab: Other: Medical writing support, Research Funding; TG Therapeautics: Research Funding. Lewis: AstraZeneca: Consultancy, Honoraria; Janssen: Honoraria, Patents & Royalties; Novartis: Patents & Royalties; Roche: Consultancy, Honoraria. Øvlisen: Abbvie: Other: Travel expenses. Santarsiere: Janssen: Honoraria. Shah: Abbvie, Janssen and Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees. Roulin: Janssen: Other: Travel and meetings. Manos: Bristol-Myers Squibb: Other: Travel and meetings. Hamad: Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Lopez-Garcia: Roche: Other: Speaker Honoraria, Travel and accommodation grants; Janssen: Other: Speaker Honoraria, Advisor, Travel and accommodation grants, Research Funding; Abbvie: Other: Speaker Honoraria, Advisor, Travel and accommodation grants; Celgene: Other: Speaker Honoraria; Fresenius: Other: Speaker Honoraria; Novonordisk: Other: Speaker Honoraria. El-Galaly: ROCHE Ltd: Ended employment in the past 24 months; Abbvie: Other: Speakers fee. Cheah: Beigene: Consultancy, Honoraria, Other: advisory; AbbVie: Research Funding; Celgene: Research Funding; AstraZeneca: Consultancy, Honoraria, Other: advisory; Loxo/Lilly: Consultancy, Honoraria, Other: advisory; TG Therapeutics: Consultancy, Honoraria, Other: advisory; Roche: Consultancy, Honoraria, Other: advisory and travel expenses, Research Funding; Janssen: Consultancy, Honoraria, Other: advisory; MSD: Consultancy, Honoraria, Other: advisory, Research Funding; Gilead: Consultancy, Honoraria, Other: advisory; Ascentage pharma: Consultancy, Honoraria, Other: advisory. Ferreri: Gilead, Novartis, Juno, PletixaPharm, Roche, Incyte: Membership on an entity's Board of Directors or advisory committees; BMS, Beigene, Pharmacyclics, Hutchison Medipharma, Amgen, Genmab, ADC Therapeutics, Gilead, Novartis, Pfizer: Research Funding. Fox: Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Other: speaker fees. Cwynarski: Gilead: Consultancy, Speakers Bureau; Incyte: Consultancy, Speakers Bureau; Atara: Consultancy; Celgene: Consultancy; Takeda: Consultancy, Other: travel to scientific conferences, Speakers Bureau; Kite, a Gilead Company: Consultancy, Other: travel to scientific conferences, Speakers Bureau; Janssen: Consultancy, Other: travel to scientific conferences; Roche: Consultancy, Other: travel to scientific conferences, Speakers Bureau; BMS/Celgene: Other: travel to scientific conferences. McKay: Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead: Honoraria, Other: Travel Support; KITE: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel Support; Janssen: Honoraria, Other: Travel Support; Beigene: Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS/Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees.

Introduction Central nervous system relapse (secondary central nervous system lymphoma -SCNS) is an uncommon but devastating complication of aggressive B-cell lymphoma. Patients (Pts) with CNS-IPI 4-6 are at greatest risk (10.2% at 2 years). Intravenous high-dose methotrexate (HD-MTX) is widely used to mitigate SCNS risk but data supporting this practice are limited. Methods We performed a multicentre, retrospective study at 21 sites in Australia, Asia, North America and Europe. Chart or registry review was performed for consecutively diagnosed pts with diffuse large B-cell lymphoma (DLBCL) and CNS-IPI 4-6, high grade B-cell lymphoma (HGBL) with rearrangements of MYC+BCL2 and/or BCL6 and primary breast/testicular DLBCL irrespective of CNS-IPI. Pts were diagnosed between 2000-2020, 18-80 years at diagnosis, and treated with curative intent anti-CD20 based chemo-immunotherapy. Pts with CNS involvement at diagnosis were excluded. HD-MTX was defined as at least one cycle of intravenous MTX at any dose. Time to SCNS was calculated from date of diagnosis (all-pts), and from the end of frontline systemic lymphoma therapy, defined as 6x21 days from diagnosis (complete response (CR-pts)), until SCNS, systemic relapse, death, or censoring, whichever came first. Cumulative risk of SCNS was computed using the Aalen-Johansen estimator treating death and systemic relapses as competing events. Adjusted cumulative risks were obtained by using an inverse probability of treatment weighting approach. The average treatment effect was computed as the difference in adjusted 5-year risk of SCNS. Results - 2300 and 1455 pts were included in the all-pts and CR-pts analyses, respectively. Baseline demographics and details of therapy are summarised in Table 1. Except for a predominance of males, pts ≤60 years and pts with ECOG 0-1 in the HD-MTX vs no HD-MTX groups, the demographics and treatments were well balanced. At a median follow up of 5.9 years (range 0.0-19.1) and 5.5 years from diagnosis (range 0.0-18.7), 201/2300 and 84/1455 pts experienced CNS events in the all-pts and CR-pts analyses respectively. For all-pts(n=2300), CNS-IPI was 4-6 in 2052(89.2%), with R-CHOP-like therapy given to 93.8%. 410 pts (17.8%) received HD-MTX (265 HD-MTX alone, 145 in combination with intrathecal methotrexate (IT-MTX);435 received IT-MTX alone;1455 received neither. There were 32/410 and 169/1890 SCNS events, with median time from diagnosis to SCNS of 8.8 and 6.7 months in the HD-MTX and no HD-MTX groups respectively. 5-year OS was 70% (95% CI, 65-76%) and 55% (95% CI 53-57%) in HD-MTX and no HD-MTX groups respectively. There was no difference in the adjusted 5-year risk of SCNS between the HD-MTX and no HD-MTX groups (8.4% vs 9.1%, adjusted hazard ratio [HR] 0.71, p=0.100) (Figure 1). For CR-pts(n=1455), CNS-IPI was 4-6 in 1267(87.0%), with R-CHOP-like therapy given to 93.3%. 284 pts (19.5%) received HD-MTX (170 HD-MTX alone, 114 with IT-MTX);298 received IT-MTX alone;873 received neither. There were 16/284 and 68/1171 SCNS events, with median time from diagnosis to SCNS of 11.0 and 10.3 months in the HD-MTX and no HD-MTX groups respectively. 5-year OS was 74%(95% CI 67-81%) and 75%(95% CI 72-78%) in the HD-MTX groups and no HD-MTX groups respectively (adjusted HR 1.08, p=0.622). There was no difference in the 5-year risk of CNS relapse between the HD-MTX and no HD-MTX groups 5.0% vs 6.0% (adjusted HR 1.03, p=0.903) (Figure 2). Exploratory analysis of the impact of HD-MTX among the highest risk groups CNS IPI 5 (n=368), CNS-IPI 6 (n=59) and CNS-IPI 6 plus all pts with testicular, renal or adrenal involvement (n=349) did not reveal differences in SCNS rates in HD-MTX treated pts. Additional subgroup analyses will be presented at the meeting. Conclusions To our knowledge, this is the largest study of the efficacy of HD-MTX in reducing SCNS events focusing exclusively on high-risk pts. The overall incidence of CNS relapse observed was consistent with previous reports in similar patient cohorts at 9%. The use of HD-MTX did not lower SCNS rates overall or when analysis was confined to CR pts at completion of curative intent therapy to compensate for potential immortal bias associated with HD-MTX therapy. Despite the limitations of the non-randomized and retrospective design, it appears unlikely that HD-MTX is associated with a clinically meaningful reduction in SCNS rates in pts with high risk for SCNS. Figure 1 Figure 1. Disclosures Lewis: AstraZeneca: Consultancy, Honoraria; Novartis: Patents & Royalties: Conference attendance; Janssen: Honoraria, Patents & Royalties: Conference attendance; Roche: Consultancy, Honoraria. Villa: Janssen: Honoraria; Gilead: Honoraria; AstraZeneca: Honoraria; AbbVie: Honoraria; Seattle Genetics: Honoraria; Celgene: Honoraria; Lundbeck: Honoraria; Roche: Honoraria; NanoString Technologies: Honoraria. Bobillo: F. Hoffmann-La Roche Ltd: Consultancy, Speakers Bureau; Gilead: Speakers Bureau. Ekstroem Smedby: Takeda: Consultancy; Janssen Cilag: Research Funding. Savage: Merck: Consultancy, Honoraria, Other: Institutional clinical trial funding; BMS: Consultancy, Honoraria, Other: Institutional clinical trial funding; AbbVie: Consultancy, Honoraria; Roche: Research Funding; Takeda: Other: Institutional clinical trial funding; Servier: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria; Astra-Zeneca: Consultancy, Honoraria; Beigene: Other: Institutional clinical trial funding; Genentech: Research Funding. Eyre: Beigene: Honoraria, Research Funding; Incyte: Consultancy; Secura Bio: Consultancy, Honoraria; Janssen: Honoraria; Gilead/KITE: Honoraria, Other: Travel support for conferences, Research Funding, Speakers Bureau; Loxo Oncology: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Consultancy, Honoraria, Other: Travel to conferences; AstraZeneca: Honoraria, Research Funding; Roche: Consultancy, Honoraria. Cwynarski: Incyte: Consultancy, Speakers Bureau; Gilead: Consultancy, Speakers Bureau; Atara: Consultancy; Celgene: Consultancy; Takeda: Consultancy, Other: travel to scientific conferences, Speakers Bureau; Kite, a Gilead Company: Consultancy, Other: travel to scientific conferences, Speakers Bureau; Janssen: Consultancy, Other: travel to scientific conferences; Roche: Consultancy, Other: travel to scientific conferences, Speakers Bureau; BMS/Celgene: Other: travel to scientific conferences. Stewart: Teva: Honoraria; Sandoz: Honoraria; Amgen: Honoraria; AstraZeneca: Honoraria; Novartis: Honoraria; Celgene: Honoraria; Gilead: Honoraria; Abbvie: Honoraria; Janssen: Honoraria; Roche: Honoraria. Bishton: Gilead: Honoraria, Other: Travel grants; AbbVie: Honoraria, Other: Travel grants; Celgene/BMS: Honoraria, Other: travel grants; Celltrion: Honoraria, Other: Travel grants; Takeda.: Honoraria, Other: Travel grants . Fox: F. Hoffmann-La Roche Ltd: Consultancy, Membership on an entity's Board of Directors or advisory committees. Joffe: Epizyme: Consultancy; AstraZeneca: Consultancy. Eloranta: Janssen Pharmaceutical NV: Other: NV. Sehn: Genmab: Consultancy; Novartis: Consultancy; Debiopharm: Consultancy. Manos: Bristol-Myers Squibb: Other: Travel and meetings. Hawkes: Specialised Therapeutics: Consultancy; Gilead: Membership on an entity's Board of Directors or advisory committees; Merck Sharpe Dohme: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Antigene: Membership on an entity's Board of Directors or advisory committees; Regeneron: Speakers Bureau; Bristol Myers Squib/Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck KgA: Research Funding; Astra Zeneca: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Roche: Membership on an entity's Board of Directors or advisory committees, Other: Travel and accommodation expenses, Research Funding, Speakers Bureau; Janssen: Speakers Bureau. Minson: Novartis: Research Funding; Hoffman La Roche: Research Funding. Dickinson: Celgene: Research Funding; Amgen: Honoraria; Takeda: Research Funding; Gilead Sciences: Consultancy, Honoraria, Speakers Bureau; MSD: Consultancy, Honoraria, Research Funding, Speakers Bureau; Janssen: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; Roche: Consultancy, Honoraria, Other: travel, accommodation, expenses, Research Funding, Speakers Bureau; Novartis: Consultancy, Honoraria, Research Funding, Speakers Bureau. Øvlisen: Abbvie: Other: Travel expenses. Gregory: Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel fees, Speakers Bureau; Janssen: Consultancy; Novartis: Consultancy. Ku: Roche: Consultancy; Antegene: Consultancy; Genor Biopharma: Consultancy. Talaulikar: Roche: Honoraria, Research Funding; Jansenn: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Takeda: Honoraria, Research Funding; EUSA Pharma: Honoraria, Research Funding. Maurer: Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Research Funding; Genentech: Research Funding; Kite Pharma: Membership on an entity's Board of Directors or advisory committees; Morphosys: Membership on an entity's Board of Directors or advisory committees, Research Funding; Nanostring: Research Funding. El-Galaly: Abbvie: Other: Speakers fee; ROCHE Ltd: Ended employment in the past 24 months. Cheah: Roche: Consultancy, Honoraria, Other: advisory and travel expenses, Research Funding; Janssen: Consultancy, Honoraria, Other: advisory; MSD: Consultancy, Honoraria, Other: advisory, Research Funding; Gilead: Consultancy, Honoraria, Other: advisory; Ascentage pharma: Consultancy, Honoraria, Other: advisory; Beigene: Consultancy, Honoraria, Other: advisory; AbbVie: Research Funding; Celgene: Research Funding; AstraZeneca: Consultancy, Honoraria, Other: advisory; Loxo/Lilly: Consultancy, Honoraria, Other: advisory; TG Therapeutics: Consultancy, Honoraria, Other: advisory.

Background: Novel strategies are needed to improve upon the 60% cure rate of upfront R-CHOP in advanced DLBCL. Single-agent immune checkpoint inhibition (ICI) has limited efficacy in heavily pre-treated DLBCL (response rate Avelumab (Av) is an anti-PDL1 monoclonal antibody with antibody dependent cell cytotoxicity (ADCC) activity which acts synergistically with rituximab (R) in vitro. We report the results of a phase II single arm study assessing safety of 1st line sequential AvR induction, R-CHOP & Av maintenance for DLBCL. Methods: Patients aged ≥18 years, ECOG 0-2 with untreated stage II-IV DLBCL and no active autoimmune disease were treated with AvR induction x2 cycles q2-weekly (Av 10mg/kg IV + R 375mg/m2 IV), followed by R-CHOP21 x 6 cycles then Av 10mg/kg x 6 cycles q2-weekly if in complete metabolic response (CMR) post R-CHOP. The primary endpoint was the rate of grade 3/4 immune-related adverse events (irAE). Secondary endpoints included overall response rate (ORR), failure free survival (FFS), overall survival (OS) and overall toxicity. Response was determined centrally by PET-CT (Lugano 2014 criteria). CMR rates by PET-CT post AvR induction and post C2 R-CHOP were exploratory endpoints. Genomic analysis was performed including next generation sequencing (NGS) based sequence variant detection, copy number analysis and structural variant detection. Results: 28 pts were enrolled from Dec 2017 to Oct 2019. Key baseline characteristics included median age 54 yrs (range 20-79); stage III/IV disease 68%; elevated LDH 61%; IPI ≥2 25%. Histology included 21 DLBCL NOS (75%; 14 GCB, 7 non-GCB by Hans algorithm), 6 primary mediastinal B-cell lymphoma (PMBCL; 21%) and 1 EBV positive DLBCL (4%). The study met its pre-specified primary endpoint of G3/4 irAE ORR post R-CHOP was 89% (all CR) (Figure 1). The ORR to 2 cycles of induction AvR was 60%, including 6 CMR (21%) across all diagnostic/histologic subgroups (n=1 PMBCL, n=2 non-GCB DLBCL, n=3 GCB DLBCL; Figures 1 and 2). Six pts (21%) progressed during AvR induction (with 1 pt completing only 1 x AvR cycle); all subsequently responded to R-CHOP. With a median follow-up of 16 months, 1-year FFS was 76% and OS 89%. Treatment was discontinued early in 5 pts; 2 during R-CHOP due to progressive disease and 3 during Av maintenance (n=1 immune hepatitis; n=1 pulmonary embolism initially reported as pneumonitis; n=1 progressive disease). Alterations in the CD274/PDCDLG2 locus were identified by NGS in 3 of 27 evaluable pts (n=2 PMBCL, n=1 EBV+ DLBCL). Full genomic analysis to identify factors associated with response will be presented. Conclusion: Sequential AvR induction, R-CHOP and Av maintenance in pts with newly diagnosed DLBCL is feasible with a manageable toxicity profile and a high CR rate. Responses to AvR alone were higher than expected based on the relapsed/refractory population and may suggest superior efficacy of ICI in the frontline setting. These results support ongoing sequential studies of immune priming with PD1/PDL1 inhibition prior to R-CHOP in DLBCL. Acknowledgements: Merck KgA for avelumab plus funding. Tour de Cure Scott Canning Early Career Grant (E Hawkes) and Wilson Centre for Lymphoma Genomics for biomarker testing. Disclosures Hawkes: Astra Zeneca: Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees, Other: Travel, Research Funding, Speakers Bureau; BMS celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Janssen-Cilag: Membership on an entity's Board of Directors or advisory committees, Other: Travel, Speakers Bureau; Merck Sharpe &Dohme: Membership on an entity's Board of Directors or advisory committees, Research Funding; takeda: Speakers Bureau; Merck KgA: Research Funding. Chong:Merck Serono: Research Funding; Bristol-Myers Squibb: Research Funding; Hutchison Medipharma: Research Funding; Bayer: Research Funding; Pharmacyclics LLC, an AbbVie Company: Research Funding; Servier: Research Funding; Isofol: Research Funding. Blombery:Novartis: Consultancy; Janssen: Honoraria; Amgen: Consultancy; Invivoscribe: Honoraria. Barraclough:Roche: Other: Conference sponsorship. Keane:Celgene: Honoraria, Other: Travel; BMS: Research Funding; Roche: Honoraria, Other: Travel, Speakers Bureau; MSD Oncology: Honoraria, Other: Travel; Gilead: Honoraria, Other: Travel, Speakers Bureau. Fong:Pfizer: Honoraria; Astellas: Honoraria; Amgen: Honoraria, Research Funding, Speakers Bureau; Novartis: Honoraria; AbbVie: Honoraria. Manos:Bristol-Myers Squibb: Other: Conference sponsorship. OffLabel Disclosure: Avelumab is an anti-PDL1 monoclonal antibody. Inhibition of the PD1/PDL1 pathway stimulates anti-tumour immunity.

Introduction Plasmablastic lymphoma (PBL) is a rare, aggressive large cell lymphoma, first described in 1997. PBL is strongly associated with immunodeficient states, such as HIV infection and solid organ transplantation, but up to one third of cases are reported to occur in immunocompetent patients. The pathogenesis of PBL is incompletely understood, though the oncogenic impact of EBV, in particular in the context of dysregulated immune surveillance, together with acquired abnormalities in the MYC pathway appear to play key roles in many cases. Plasma cell markers such as CD138 and CD38 are typically positive, as well as CD30 in a significant subset. Classical B cell markers such as CD20, CD19 and PAX5 are typically absent. The literature on clinical outcomes in PBL is generally limited to small, single-centre case series. Reports describe an aggressive disease of poor prognosis, with median survival of 8 to 15 months, with one series reporting a longer median survival of 32 months. Methods We retrospectively identified patients diagnosed with PBL between 1999 and 2019 from 16 sites across Australia, the United Kingdom and Canada. Patients aged ≥18 years with confirmed tissue diagnosis of PBL at their local treating centre were included. Factors associated with overall survival (OS) were analysed using Cox regression, stratified by site to account for heterogeneity across sites. Risk time for mortality began on the date of diagnosis and ended on the date of death. Patients who were alive, lost to follow-up or transferred to another centre for care, were censored on the date of last follow-up. Risk factors analysed included age, year of diagnosis, HIV status, MYC rearrangement status, CD30 status, lactate dehydrogenase level, disease stage by Lugano consensus criteria, and bone marrow involvement. Results We identified 197 patients with PBL (Table 1). The median age at diagnosis was 55 years (range 18-95) and there was a male predominance (69%). 37% of patients were HIV positive, 56% were HIV negative and 7% were either not tested or had missing results. Other immunosuppressive risk factors included solid organ transplant, allogeneic stem cell transplant (SCT), and immunosuppressive medication. No immunodeficient state was detected in 44%. Fifty per cent of patients were stage IV at diagnosis. Fifty-four per cent were staged using PET/CT. The median follow-up time from diagnosis was 1.36 years, with the longest follow up out to 18.4 years. There were 87 deaths (44%). For patients receiving first-line treatment with curative intent, the rate of complete remission was 57% (103 of 181 patients). Most patients (53%) received CHOP (cyclophosphamide, doxorubicin, vincristine, prednisolone)-based chemotherapy as first line, and 27% treatment of higher intensity than CHOP. Rituximab was administered to 20% and 10% were exposed to proteasome inhibitors as part of first line therapy. Five percent of patients underwent autologous SCT in first remission, and a further 5% after first relapse or later. The median survival time was 4.8 years, with a 5-year OS of 49% and 10-year OS of 45% (figure 1). In multivariate analysis the only adverse factors associated with OS were bone marrow involvement and stage IV disease. Patients without bone marrow involvement at diagnosis had improved OS, compared to those who did (hazard ratio (HR) 0.36, 95%CI 0.18-0.72, p=0.004) (figure 2). There was an increasing trend for mortality with higher disease stages (p-trend=0.002). The median survival was 14.1 years for stage I, 10.7 years for stage II, 5.1 years for stage III and 1.2 years for stage IV. However, only stage IV disease was independently associated with inferior OS in multivariate analysis (HR 2.93, 95%CI 1.43-6.00, p=0.003) (figure 3). OS did not change depending upon year of diagnosis. Conclusion We report a multinational retrospective cohort of patients diagnosed with PBL and to our knowledge the largest single series of PBL to date. OS was longer than previously published data, particularly in patients with early-stage disease. However, patients with stage IV disease and baseline bone marrow involvement had inferior OS. HIV infection did not affect outcome. These findings suggest that baseline bone marrow biopsy and PET staging are useful prognostic tools. There is also an ongoing need for the evaluation of the predictive value of PET imaging and novel agents in PBL, especially in higher-risk disease. Disclosures Di Ciaccio: Jansen: Honoraria, Other: travel and accomodation grant. Cwynarski:Takeda: Consultancy, Other: Conference/travel support; Roche: Consultancy, Other: Conference/travel support. Burton:Celgene: Honoraria; Leeds Teaching Hospitals NHS Trust: Current Employment; Takeda: Honoraria, Other: Travel Support; BMS: Honoraria; Roche: Honoraria, Other: Travel Support. Kuruvilla:Antengene: Honoraria; Janssen: Honoraria, Research Funding; Roche: Consultancy, Honoraria, Research Funding; Seattle Genetics: Consultancy, Honoraria; Karyopharm: Consultancy, Honoraria; Gilead: Consultancy, Honoraria; AbbVie: Consultancy; AstraZeneca Pharmaceuticals LP: Honoraria, Research Funding; Merck: Consultancy, Honoraria; Celgene Corporation: Honoraria; Amgen: Honoraria; TG Therapeutics: Honoraria; Pfizer: Honoraria; Novartis: Honoraria; Bristol-Myers Squibb Company: Consultancy. McKay:Greater Glasgow and Clyde Health Board: Current Employment; Roche, Gilead, Takeda, Janssen: Other: For lectures etc; Roche: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BeiGene: Membership on an entity's Board of Directors or advisory committees; Janssen: Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company), Speakers Bureau; TAKEDA: Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company), Speakers Bureau. Linton:BeiGene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Conference/travel support; Roche: Consultancy, Speakers Bureau; Gilead: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company), Patents & Royalties; Janssen: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Hartley-Taylor: Honoraria; The Christie NHS Foundation Trust and The University of Manchester: Current Employment. Manos:Bristol-Myers Squibb: Other: Conference sponsorship. Hamad:Abbvie: Honoraria; Novartis: Honoraria.

BACKGROUND Bendamustine and Rituximab (BR) therapy is recommended in international consensus guidelines for treatment of Waldenström Macroglobulinaemia (WM) in both frontline and relapsed settings. The optimal dose and schedule of Bendamustine is not well established. Dose options include 90mg/m2 or 70mg/m2 on days 1&2 of each of 6 cycles (total Bendamustine dose of 1080mg/m2 and 840mg/m2, respectively) +/- reduction from 6 to 4 cycles. AIMS Determine response rates (IWWM criteria), PFS and toxicity following BR in frontline and relapsed settings Determine the impact of depth of response and Bendamustine dose on PFS METHODS A multicentre, retrospective cohort analysis was undertaken of consecutive WM patients treated with BR in the frontline or relapsed settings. Data were collected from 17 sites across 4 countries, including UK centres participating in the Rory Morrison Registry. RESULTS Data from Sep 2010 to May 2020 were collected for 250 patients. Frontline (n=139, 55.6%) and relapsed (n=111, 44.4%) cohorts were matched in terms of sex, age at commencement of BR, ECOG score, and baseline parameters including: haemoglobin, platelet count, bone marrow infiltration, and presence of adenopathy, splenomegaly and extranodal disease. At a median follow up of 37 months, disease progression had occurred in 25 frontline patients (18.0%) and 48 relapsed patients (43.2%; p Major responses (≥PR) differed significantly between frontline and relapsed cohorts (91.4% vs 73.9%, respectively; p Best response significantly impacted on PFS and OS. Two-year predicted PFS rates for those achieving CR/VGPR vs PR were 96% vs 82%, respectively (p=0.002, Fig. 1A). Median OS was 83 months after achieving CR/VGPR, 65 months after achieving PR/MR and 28 months after achieving SD/PD (p Relapsed patients had received 1 (n=53, 47.7%), 2 (n=28, 25.2%) or ≥3 (n=30, 27.0%) prior therapies. PFS was significantly longer in the frontline cohort compared with recipients of ≥2 prior lines of treatment, but not between cohorts treated frontline vs after 1 prior therapy line (Fig. 1B). Rates of toxicity-related treatment truncation were significantly lower in the frontline setting (17.3% vs 35.1%; p Frontline patients received higher total Bendamustine doses than relapsed patients (median total dose 1080mg/m2 vs 720mg/m2; p Age did not significantly affect tolerated dose in the frontline cohort, with similar median total Bendamustine doses in the CONCLUSION Outcomes for WM patients following BR are excellent. Frontline patients tolerate higher doses of Bendamustine, and achieve deeper responses and longer PFS than relapsed patients. In both settings, attaining CR/VGPR results in superior PFS and OS. Our data clearly delineate the Bendamustine doses required to achieve optimum PFS. At frontline, 6 cycles of 90mg/m2 on days 1&2 is superior to lower doses with respect to response and PFS. In the relapsed cohort, maximum response and PFS benefit are seen with 4 cycles of 90mg/m2 on days 1&2; a starting dose of 70mg/m2 on days 1&2 is also sufficient provided 5-6 cycles are administered. Disclosures Menne: Kyowa Kirin: Other: Travel expenses; AstraZeneca: Research Funding; Pfizer: Honoraria, Other; Atara: Honoraria; Novartis: Honoraria, Research Funding; Kite/Gilead: Honoraria, Other: Travel expenses; Celgene: Honoraria, Other: Travel expenses; Daiichi Sankyo: Honoraria; Amgen: Honoraria, Other: Travel expenses; Janssen: Honoraria, Research Funding; Takeda: Honoraria; Bayer: Other: Travel expenses; Roche: Honoraria. Talaulikar:Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Research Funding. Pratt:Binding Site Ltd: Other: Personal fees; Amgen: Other: Personal fees; Janssen: Other: Personal fees; Celgene: Other: Personal fees; Takeda: Other: Personal fees; Gilead: Other: Personal fees; Sanofi-Genzyme: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Beigene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharm: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Manos:Bristol-Myers Squibb: Other: Conference sponsorship. Gavriatopoulou:Genesis Pharma: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Karyopharm: Consultancy, Honoraria. Minnema:Kite, a Gilead Company: Speakers Bureau; Celgene: Other: travel support, Research Funding; Servier: Consultancy; Amgen: Consultancy. El-Sharkawi:Roche: Other: Conference fees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees. Kersten:Kite, a Gilead Company: Consultancy, Honoraria, Other: travel support; Novartis: Consultancy, Honoraria, Other: travel support; Miltenyi: Consultancy, Honoraria, Other: travel support; Roche: Research Funding; Takeda: Research Funding; Celgene: Research Funding. McCarthy:Abbvie: Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria. Bishton:Janssen: Consultancy; Takeda: Other: Travel/accommodations/expenses, Research Funding; Roche: Other: Travel/accommodations/expenses, Research Funding; Gilead: Other: Travel/accomodations/expenses, Research Funding; AbbVie: Research Funding. Follows:Roche: Consultancy, Other: Paid lecturing; Karyopharm: Consultancy, Other: Paid lecturing; Janssen: Consultancy, Other: Paid lecturing; Abbvie: Consultancy, Other: Paid lecturing; Bristol Myers Squibb: Consultancy, Other: Paid lecturing; Astrazeneca: Consultancy, Other: Paid lecturing. Wechalekar:Janssen, Takeda, Caelum, Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees. D'Sa:BeiGene: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Sanofi: Honoraria.

Mantle cell lymphoma (MCL) is an uncommon and typically aggressive form of lymphoma. Although often initially chemosensitive, relapse is common. Several induction and conditioning regimens are used in transplant-eligible patients, and the optimal approach remains unknown. We performed an international, retrospective study of transplant-eligible patients to assess impact of induction chemoimmunotherapy and conditioning regimens on clinical outcomes. We identified 228 patients meeting inclusion criteria. Baseline characteristics were similar among the induction groups except for some variation in age. The type of induction chemoimmunotherapy received did not influence overall response rates (ORRs) (0.43), progression-free survival (PFS) (P > .67), or overall survival (OS) (P > .35) on multivariate analysis (PFS and OS). Delivery of autologous stem cell transplant (ASCT) was associated with favorable PFS and OS (0.01) on univariate analysis only; this benefit was not seen on multivariate analysis-PFS (0.36) and OS (0.21). Compared with busulfan and melphalan (BuMel), the use of the carmustine, etoposide, cytarabine, melphalan (BEAM)-conditioning regimen was associated with inferior PFS (HR = 2.0 [95% CI 1.1-3.6], 0.02) but not OS (HR = 1.1 [95% CI 0.5-2.3], 0.81) on univariate analysis only. Within the limits of a retrospective study and modest power for some comparisons, type of induction therapy did not influence ORR, PFS, or OS for transplant-eligible patients with MCL. International efforts are required to perform randomized clinical trials evaluating chemoimmunotherapy induction regimens.

Background: Most DLBCL & FL responds well to first line treatment, yet relapsed disease outcomes are poor. Immune checkpoint inhibition (ICI) with PD/PD1 inhibitors (PD1i) yield high response rates in some lymphomas; though single agent PD1i yields a disappointing ORR of 10% in heavily pre-treated DLBCL, some responses are durable. RT stimulates anti-tumour immunity through several mechanisms and may enhance response to ICI. Concurrent ICI & RT is synergistic in preclinical studies & solid tumours, improving local & distant (abscopal) response. RT to multiple disease sites may broaden the spectrum of tumour antigen release and overcome clonal variation between disease sites to further augment the immune response. A dose-response relationship between RT and antigen release has yet to be established. This phase I dose escalation study aims to determine the safety profile of RT in combination with durvalumab, an anti-PD-L1 monoclonal antibody, in relapsed/refractory DLBCL and FL. Study Design and Methods: RaDD (NCT03610061) is a phase I dose escalation study to determine the safety profile of escalating dose and number of sites of RT in combination with durvalumab in relapsed/refractory (RR) DLBCL & FL. Eligible patients (pts) have received ≥ 1 prior line of therapy and are ineligible for or relapsed after autologous stem cell transplant (auto-SCT). Pts with active autoimmune disease, CNS involvement, prior allogeneic-SCT or chronic steroid use are excluded. RT dose and site escalation proceeds according to a 3+3 design with 6 dose levels (cohorts 1-6). Treatment comprises external beam RT to target site(s) daily for 5 days (Cohorts 1-5); Cohort 6 receives a further 5 daily fractions (max 30Gy). Durvalumab 1500mg IV commences day 2 of RT and continues 4-weekly until disease progression. Pts can continue until a second radiological progression if clinical benefit is ongoing. The dose limiting toxicity period is 28 days from start of RT. The primary endpoint is the toxicity, drug pharmacokinetics, maximum tolerated dose (MTD) and recommended phase two dose (RP2D) of simultaneous RT and durvalumab. Secondary endpoints include response rates, progression-free survival and overall survival. Correlative studies will examine the tumour-immune system interaction; an exploratory PET substudy with novel tracers for durvalumab (89Zr-Durvalumab) & CD8+ T cells (89Zr -Df-IAB22M2C) will also be performed. Projected enrolment for determination of the MTD and RP2D is 6-30 pts pending toxicity. Recruitment will continue to 36 pts for secondary endpoint analysis. 22 pts are enrolled to date in the main study, with 2 patients enrolled in the PET-substudy. Acknowledgements: Victorian Cancer Agency (grant funding - TRP16006), Astra Zeneca (durvalumab and funding), Celgene (funding), Imaginab (89Zr -Df-IAB22M2C). Citation Format: Kate Manos, Richard Khor, Geoffrey Chong, Jodie Palmer, Michael MacManus, Colm Keane, Andrew M. Scott, Jake Shortt, David Ritchie, Leonid Churilov, Laura Johnston, Tom Witkowski, Allison Barraclough, Sze Ting Lee, Wendi Lin, Rachel Koldej, Eliza Hawkes. Phase I Dose Escalation Study of Radiotherapy and Durvalumab (MEDI4736) in Relapsed or Refractory Diffuse Large B-cell Lymphoma (DLBCL): The RaDD Study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT208.

7560 Background: Standard of care immunochemotherapy in front-line (1L) follicular lymphoma (FL) is highly efficacious but not without significant toxicity. High rates of grade 3-5 adverse events (AEs), primarily infection and bone marrow suppression, are experienced in up to 75% of patients. A more tolerable but equally effective approach is required. PD-1 inhibition, in combination with rituximab (R), increases T cell anti-tumour effect & enhances NK cell antibody dependent cell cytotoxicity, with proven efficacy in relapsed FL. The concept of ‘priming’ the immune system with nivolumab (N) prior to tumour-directed therapy has rationale and evidence, but the safety of this approach in 1L FL is not described. Methods: ‘1st FLOR’ (NCT03245021) is an open-label, multi-centre, phase 2, Simon’s 2-stage study of N + R (N = 39). Key eligibility were stage III-IV grade 1-3A FL requiring 1L systemic therapy; ECOG ≤2; adequate organ function. All patients (pts) receive induction N 240mg IV 2-weekly for 4 cycles. Pts with complete response (CR) receive 4 further cycles of 240mg IV N monotherapy then 12 cycles of maintenance N 480mg IV 4-weekly. Pts with < CR had 240mg N plus 375mg/m2 IV R 2-weekly for 4 cycles followed by maintenance N+R (N 480mg 4 weekly for 12 cycles; R 12 weekly for 8 cycles). Primary endpoint (EP) was ≥ G3 toxicity rate during induction. Secondary EPs; response rate by Lugano response criteria, overall toxicity, PFS, OS. Results: Between September 2017 to March 2020, 39 pts were enrolled. Baseline characteristics included median age of 54 (range: 28-79). stage IV disease in 67%, B Symptoms & bulk (≥7cm) in 23% each, intermediate-high risk FLIPI in 74%. The primary EP was met, with only 16 pts (41%) having ≥G3 toxicity at end of induction. Non-immune AEs were predominantly G1-2; most commonly infection (67%) & fatigue (64%). G3-4 Immune-related AEs were infrequent and included pancreatitis plus hepatitis (N = 1), pancreatitis alone (N = 1), rash (N = 1), transaminitis (N = 2), hypocortisolism (N = 1), hyperglycaemia (N = 3) and asymptomatic lipase/amylase increase (N = 3). Median follow-up was 17.5 months (range: 7-39). Overall response rate was 92% (36/39) with CR in 54% (21/39). Median time to CR was 5 months (m) (range: 2-25). Nine pts (23%) discontinued treatment; 7 due to progressive disease (1 pt died of transformed FL), 2 developed constitutional symptoms (1 stable disease, 1 partial response). In 25 evaluable pts, 12m PFS & OS is 72% (CI 51-88) & 96% (CI 80-100). Biomarker analysis is in progress. Conclusions: Immune-priming with single-agent N, then combination N+R in 1L FL is associated with favourable toxicity and high ORR & CR rates potentially providing an alternative to chemotherapy. Acknowledgements: Bristol-myers Squibb provided funding and nivolumab for this study. Clinical trial information: NCT03245021.

TPS8075 Background: Most DLBCL & FL responds well to first line treatment, yet relapsed disease outcomes are poor. PD1/PDL1 inhibitors yield high response rates in some lymphomas, but single agent therapy in heavily pre-treated pts are disappointing. RT stimulates anti-tumor immunity through several mechanisms and may enhance response to immune checkpoint inhibition (ICI). Concurrent ICI & RT is synergistic in preclinical studies & solid tumors, improving local & distant (abscopal) response. RT to multiple disease sites may broaden the spectrum of tumor antigen release and overcome clonal variation between disease sites to further augment the immune response. Methods: RaDD (NCT03610061) is a phase I, 3+3 dose escalation study to determine the safety profile of escalating dose & number of sites of RT in combination with Durvalumab (anti-PD-L1 antibody) in RR DLBCL & FL. Eligible pts (i.e. ≥1 prior therapy, ineligible for auto-SCT, no contraindication to PDL1i) receive 5 fractions of external beam RT to target site(s). 5 RT dose & site levels are included (dose range 2.5Gy-20Gy to 1-3 sites). Durvalumab 1500mg IV commences day 2 of RT and continues 4-weekly until confirmed disease progression. The DLT period is 28 days from start of RT. Primary endpoint is the recommended phase two dose (RP2D) of RT in combination with durvalumab. Secondary endpoints include response rates, PFS & OS. Correlative studies will examine the tumour-immune system interaction; an exploratory PET substudy with novel tracers for durvalumab (89Zr-Durvalumab) & CD8+ T cells (89Zr -Df-IAB22M2C) will also be performed. Projected enrollment for determination of maximum tolerated dose (MTD) & RP2D is 6-30 pts pending toxicity. Recruitment will continue to 36 pts for secondary endpoint analysis. 9 pts are enrolled across cohorts 1-3 to date. Clinical trial information: NCT03610061 .

Background: Although ~60% of patients with DLBCL are cured with frontline therapy, outcomes for those with relapsed/refractory disease remain poor. Tumour cells exploit immune checkpoint pathways, including the PD1/PDL1 axis, to evade and inhibit host anti-tumour immune responses. PD1/PDL1 expression and cytogenetic 9p24 alterations in some DLBCL subtypes provide additional rationale for PDL1 inhibition (PD-L1i) in DLBCL. Though single agent PD1i yields a disappointing ORR of 10-30% in heavily pre-treated DLBCL, some responses are durable.1 Radiotherapy (RT) is an established mechanism of stimulating anti-tumour immunity via increased circulating tumour antigen, immunogenic cell death and T-cell recruitment and activation in the tumour microenvironment. Synergy between concomitant immune checkpoint inhibition (ICI) and RT has been demonstrated in preclinical studies2 and solid tumours; a recent study in non-small cell lung cancer demonstrated an ORR of 36% with pembrolizumab + RT compared with 18% with pembrolizumab alone.3 RT hypofractionation appears critical to the abscopal effect when used with ICI,4 and concurrent RT and PD-L1i is more successful than sequential treatment.5 RT to multiple sites may broaden the spectrum of tumour antigen released and overcome clonal variation between disease sites; a dose-response relationship between RT and antigen release has yet to be established. This phase I study aims to determine the safety profile of escalating dose and number of sites of RT in combination with Durvalumab (MEDI4736), an anti-PD-L1 monoclonal antibody, in relapsed/refractory DLBCL, including primary refractory DLBCL and transformed follicular lymphoma. Study Design and Methods: RaDD (NCT03610061) includes eligible pts who have received ≥1 prior line of therapy and are ineligible for or relapsed after autologous stem cell transplantation (SCT). Pts with active autoimmune disease, CNS involvement, prior allogeneic SCT or chronic steroid use are excluded. Treatment comprises external beam RT to target site(s) daily for 5 days (Fig 1). Durvalumab 1500mg IV commences on day 2 of RT and continues 4-weekly until disease progression. Pts can continue until a second radiological progression if clinical benefit is ongoing. The primary endpoint is the toxicity, drug pharmacokinetics, maximum tolerated dose (MTD) and recommended phase two dose (RP2D) of simultaneous RT plus durvalumab. Secondary endpoints are response rates; progression free survival; and overall survival. An exploratory PET substudy will employ novel tracers to characterise the local and systemic immune response via assessment of the biodistribution of durvalumab (with 89Zr-Durvalumab) and CD8+ T cells (with 89Zr -Df-IAB22M2C). Biomarker sample collection is synchronised with PET response assessment. A comprehensive translational substudy will apply high throughput technologies to tissue and sequential blood samples to characterise the tumour-immune system interaction and correlate novel host, tumour and tumour microenvironment factors with treatment responses and toxicity. Findings may inform the RP2D. RT dose and site escalation will proceed according to a 3+3 design with 5 dose levels (cohorts 1-5, Fig 2). The dose limiting toxicity assessment window is the first 28 days. Projected enrolment for determination of MTD and RP2D is 6-30 pts pending toxicity. Recruitment will continue to a total of 36 pts to allow for secondary endpoint analysis. 5 pts have been enrolled to date. Acknowledgements: Victorian Cancer Agency (funding), Astra Zeneca (durvalumab and funding), Celgene (funding), Imaginab (89Zr -Df-IAB22M2C) References: 1. Ansell SM et al. Nivolumab for Relapsed/Refractory Diffuse Large B-Cell Lymphoma in Patients Ineligible for or Having Failed Autologous Transplantation. J Clin Oncol. 2. Deng L et al. Irradiation and anti-PD-L1 treatment synergistically promote antitumor immunity in mice. J Clin Invest. 3. Theelen W et al. Effect of Pembrolizumab After Stereotactic Body Radiotherapy vs Pembrolizumab Alone on Tumor Response in Patients With Advanced Non-Small Cell Lung Cancer. JAMA oncology. 4. Golden EB et al. An abscopal response to radiation and ipilimumab in a patient with metastatic non-small cell lung cancer. Cancer Immunol Res. 5. Sharabi AB et al. Radiation and checkpoint blockade immunotherapy: radiosensitisation and potential mechanisms of synergy. Lancet Oncology. Disclosures Hawkes: Janssen-Cilag: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck Sharp & Dohme: Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Research Funding, Speakers Bureau; Roche: Research Funding; Takeda: Speakers Bureau; Astra Zeneca: Research Funding; Merck KgA: Research Funding; Mundi pharma: Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche/Genentech: Membership on an entity's Board of Directors or advisory committees, Other: Travel expenses, Speakers Bureau. Manos:Janssen: Honoraria; Novo Nordisk Pharmaceuticals: Other: Travel. Chong:Merck Serono: Research Funding; Hutchison Medipharma: Research Funding; Pharmacyclics: Research Funding; Novartis: Research Funding; Bayer: Research Funding; BMS: Research Funding. MacManus:National Health and Medical Research Council Australia: Research Funding. Keane:MSD: Consultancy; Celgene: Consultancy; Gilead: Consultancy; BMS: Research Funding; Roche: Consultancy, Other: Travel Grant. Scott:Cancer Council Victoria: Research Funding; Cancer Australia: Research Funding; Avipep: Consultancy; IBA: Consultancy; Paracrine Therapeutics: Equity Ownership, Patents & Royalties; Life Science Pharmaceuticals: Equity Ownership; NHMRC: Research Funding; Abbvie: Consultancy, Patents & Royalties; Cure Brain Cancer: Research Funding; Medimmune: Consultancy; Humanigen: Patents & Royalties. Shortt:Celgene: Consultancy, Speakers Bureau; BMS: Consultancy, Speakers Bureau; Novartis: Consultancy, Speakers Bureau; Astex: Research Funding; Amgen: Research Funding; Gilead: Speakers Bureau; Takeda: Speakers Bureau. Ritchie:Amgen: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy; BMS: Research Funding; Takeda: Research Funding; Beigene: Research Funding; Imago: Research Funding; Novartis: Honoraria; Sanofi: Honoraria. Lee:Australian Nuclear Science and Technology Organisation: Membership on an entity's Board of Directors or advisory committees. Koldej:NanoString Technologies: Other: Travel grant. OffLabel Disclosure: Durvalumab is an anti-PD-L1 monoclonal antibody.

Background: The effectiveness of anti-tumour T and NK cells in malignancy is mitigated by the engagement of the immune check point pathway with PD-1/PDL-1 interaction.1,2 Immune manipulation with PD-1 inhibition, in combination with rituximab, can increase T cell anti-tumour effect and enhance NK cell antibody dependent cell cytotoxicity (ADCC), with this combination proving efficacious in rituximab-refractory follicular lymphoma (FL).3 The concept of 'priming' the immune system with nivolumab, a PD-1 inhibitor, prior to tumour-directed therapy has rationale and evidence, but the safety of this approach in previously untreated FL is not described.4 We are conducting a phase II Simon's two stage study to assess the feasibility and safety of combination nivolumab and rituximab in these patients and present the pre-planned interim analysis results. Methods: The 1st FLOR study (NCT03245021) is an ongoing open-label, multi-centre, phase 2 study of nivolumab and rituximab in patients with previously untreated stage III-IV grade 1-3A FL requiring systemic therapy. Eligible patients are ECOG ≤ 2 and do not require urgent debulking therapy. All patients receive induction nivolumab 240mg intravenously (IV) every 2 weeks for 4 cycles. Patients achieving complete response (CR) based on PET/CT Lugano criteria receive a further 4 cycles of 240mg IV nivolumab monotherapy then maintenance nivolumab 480mg IV every 4 weeks for 12 cycles. Patients achieving less than CR received 240mg nivolumab plus 375mg/m2 IV rituximab every 2 weeks for 4 cycles. Those achieving a response at the end of 8 cycles of nivolumab and rituximab continue maintenance nivolumab 480mg IV every 4 weeks for 12 cycles PLUS rituximab 375mg/m2 every 12 weeks for 8 cycles. PET/CT assessment is performed at baseline, after 4 cycles of nivolumab, after 8 cycles of nivolumab +/-rituximab and prior to maintenance cycle 6. The primary end point is safety, with a pre-planned analysis after the first 19 patients completed induction treatment with 8 cycles of nivolumab +/- rituximab. Secondary endpoints included response rates and time to treatment failure (TTF). The planned total study population is 39 patients, with a Simon's two-stage design. We report the results of the pre-planned interim analysis. Results: Baseline characteristics are summarised in Table 1. Treatment-related adverse events (AEs) were predominantly grade 1-2 with fatigue (74%), infection (59%), nausea/vomiting (36%) and abdominal pain (36%) being the most common (Table 2). Immune-related (IR) AEs were reported in 79% of all patients. Grade 3-4 IRAEs were uncommon and included; pancreatitis plus hepatitis (1 patient); transaminitis (n=1), hyperglycaemia (n=2) and asymptomatic lipase increase (n=2) (Table 3). Median follow-up was 17 months. The overall response rate (ORR) was 84% (16/19) with 47% (9/19) achieving CR, 37% (7/19) partial response (PR), 5% (1/19) stable disease and 11% (2/19) progressive disease (PD) as best response (Figure 1A and 1B). Median time to CR was 5 months. Median TTF was 3.4 months. Three pts (16%) discontinued study treatment; 2 due to early disease progression (1 with suspicion of transformation in cycle 2) and 1 due to development of constitutional symptoms with stable disease. Conclusion: In this planned interim analysis, the combination of nivolumab and rituximab in treatment naive follicular lymphoma is associated with a favourable toxicity profile and high overall and complete response rates potentially providing patients an alternative to traditional chemotherapy. Acknowledgements: Bristol-myers Squibb provided funding and nivolumab for this study. References: 1. Salmaninejad A, et al. PD-1/PD-L1 pathway: Basic biology and role in cancer immunotherapy. J Cell Physiol. 2. Ferris RL, et al. Rationale for combination of therapeutic antibodies targeting tumor cells and immune checkpoint receptors: Harnessing innate and adaptive immunity through IgG1 isotype immune effector stimulation. Cancer Treat Rev. 3. Nastoupil LJ, et al. Response rates with pembrolizumab in combination with rituximab in patients with relapsed follicular lymphoma: Interim results of an on open-label, phase II study. J Clin Oncol. 4. Park SE, et al. Increased Response Rates to Salvage Chemotherapy Administered after PD-1/PD-L1 Inhibitors in Patients with Non-Small Cell Lung Cancer. J Thorac Oncol. Disclosures Chong: Novartis: Research Funding; Hutchison Medipharma: Research Funding; Pharmacyclics: Research Funding; Bayer: Research Funding; Merck Serono: Research Funding; BMS: Research Funding. Gilbertson:Roche: Speakers Bureau; Roche: Honoraria. Grigg:Janssen: Membership on an entity's Board of Directors or advisory committees; MSD: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; Roche: Other: Travel. Ritchie:Amgen: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy; BMS: Research Funding; Takeda: Research Funding; Beigene: Research Funding; Imago: Research Funding; Novartis: Honoraria; Sanofi: Honoraria. Koldej:NanoString Technologies: Other: Travel grant. Manos:Novo Nordisk Pharmaceuticals: Other: Travel; Janssen: Honoraria. Hawkes:Astra Zeneca: Research Funding; BMS: Research Funding, Speakers Bureau; Merck KgA: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen-Cilag: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Mundi pharma: Research Funding; Roche/Genentech: Membership on an entity's Board of Directors or advisory committees, Other: Travel, Speakers Bureau; Merck Sharpe & Dohme: Membership on an entity's Board of Directors or advisory committees; Roche: Research Funding; Takeda: Speakers Bureau; Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding. OffLabel Disclosure: Nivolumab is a fully human IgG4 monoclonal antibody against programmed cell death 1 (PD-1). The PD-1 pathway is an immune system checkpoint that may be exploited by tumour cells to escape immune surveillance. By blocking the binding of the PD-1 receptor to the PD-1 and PD- 2 ligands, nivolumab reactivates tumour-specific cytotoxic T-lymphocytes in the tumour microenvironment to restimulate anti-tumour immunity.

Background: Whilst up to 60% of DLBCL patients (pts) are cured with frontline R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone), outcomes remain poor for those with relapsed or refractory disease. 1 New strategies to improve frontline cure rates are needed. Tumour cells exploit immune checkpoint pathways, including the PD1/PDL1 axis, to evade the host immune system. PD1/PDL1 over-expression and cytogenetic 9p24 alterations in some DLBCL subtypes provide additional rationale for immune checkpoint inhibition (ICI) in this disease. Although single agent PD1 inhibition yields an overall response rate (ORR) of only 10%-30% in heavily pre-treated unselected DLBCL, many responses are durable.2 Immunosuppressive effects of prior therapy may contribute to the modest response to ICI in relapsed disease. A number of considerations influence the incorporation of ICI into upfront DLBCL treatment. Although concurrent PD1/PDL1 inhibition and R-CHOP is safe,3 corticosteroid-related immunosuppression may negate PDL1-inhibitor efficacy. Evidence supporting host immune priming with ICI prior to chemotherapy is promising,4 and maintenance ICI post chemotherapy may assist with immune reconstitution and enhance the anti-tumour immune response. Additionally, avelumab (Av, an anti-PDL1 monoclonal antibody with antibody dependent cellular cytotoxicity activity) acts synergistically with rituximab (R) in vitro (unpublished data, Pfizer 2016). Thus, we present our phase II study assessing the safety of sequential Av+R induction, R-CHOP and Av maintenance as upfront therapy for DLBCL. Methods: AvR-CHOP (NCT03244176) is a phase II multicentre single-arm trial of Av induction + maintenance with R-CHOP in newly-diagnosed adult pts with DLBCL. Pts aged >18 years, ECOG 0-2, stage II-IV and with no active autoimmune disease are eligible. Exclusion criteria include the necessity for urgent cytoreduction, grade 3B or transformed follicular lymphoma, CNS involvement, chronic steroid use, prior transplantation or pneumonitis. Treatment (Fig 1) comprises R (375mg/m2 IV) + Av (10mg/kg IV) x 2 cycles q2-weekly, followed by R-CHOP21 x 6 cycles. Maintenance Av x 6 cycles q2-weekly is given to patients achieving a complete metabolic response by PET/CT at the end of R-CHOP. PET/CT is performed after R+Av 2 cycles, cycle 2 R-CHOP, end of R-CHOP and end of Av maintenance. The primary endpoint is immune-related toxicity within 30 days post-treatment. Secondary endpoints include ORR, failure free survival (FFS), overall survival (OS) and toxicity of treatment. Complete metabolic response rates by PET-CT after R-Av induction and after C2 R-CHOP are exploratory endpoints. Biomarker sample collection is synchronised with PET response assessment. A comprehensive translational substudy will apply high throughput technologies to tissue and sequential blood samples to characterise the tumour-immune system interaction and correlate novel host, tumour and tumour microenvironment factors with treatment responses and toxicity. Planned enrolment is 28 pts across 3 sites in Australia. The study follows a Simon 1 stage design, with an 80% power and a 1-sided alpha of 0.05 to rule out an Av-related toxicity rate of 30% (p0=70%), assuming an expected immune related toxicity rate of 10% [p1=90%]. 23 pts are enrolled to date. Acknowledgements: Merck KgA (avelumab and funding) References: 1. Cunningham D et al. Rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisolone in patients with newly diagnosed diffuse large B-cell non-Hodgkin lymphoma: a phase 3 comparison of dose intensification with 14-day versus 21-day cycles. Lancet (London, England). 2013;381(9880):1817-26. 2. Ansell SM et al. Nivolumab for Relapsed/Refractory Diffuse Large B-Cell Lymphoma in Patients Ineligible for or Having Failed Autologous Transplantation: A Single-Arm, Phase II Study. J Clin Oncol. 2019;37(6):481-9. 3. Nowakowski GS et al. Safety and efficacy of PD-L1 inhibitor durvalumab with R-CHOP or R2-CHOP in subjects with previously untreated, high-risk DLBCL. Journal of Clinical Oncology. 2019;37(15_suppl):7520-. 4. Park SE et al. Increased Response Rates to Salvage Chemotherapy Administered after PD-1/PD-L1 Inhibitors in Patients with Non-Small Cell Lung Cancer. Journal of thoracic oncology : official publication of the International Association for the Study of Lung Cancer. 2018;13(1):106-11. Disclosures Hawkes: Roche/Genentech: Membership on an entity's Board of Directors or advisory committees, Other: Travel expenses, Speakers Bureau; Bristol-Myers Squibb: Research Funding, Speakers Bureau; Astra Zeneca: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck KgA: Research Funding; Janssen-Cilag: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Mundi pharma: Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Research Funding; Takeda: Speakers Bureau; Merck Sharp & Dohme: Membership on an entity's Board of Directors or advisory committees. Manos:NovoNordisk Pharmaceuticals: Other: Travel; Janssen: Honoraria. Renwick:Celgene: Consultancy; Roche: Honoraria. Grigg:MSD: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Roche: Other: Travel. Scott:Medimmune: Consultancy; Abbvie: Consultancy, Patents & Royalties; IBA: Consultancy; Avipep: Consultancy; Life Science Pharmaceuticals: Equity Ownership; Paracrine Therapeutics: Equity Ownership, Patents & Royalties; NHMRC: Research Funding; Cancer Australia: Research Funding; Cancer Council Victoria: Research Funding; Cure Brain Cancer: Research Funding; Humanigen: Patents & Royalties. Lee:Australian Nuclear Science and Technology Organisation: Membership on an entity's Board of Directors or advisory committees. Fong:Astellas: Consultancy; Amgen: Consultancy, Research Funding, Speakers Bureau; Pfizer: Consultancy, Speakers Bureau; Novartis: Speakers Bureau. Rooney:GenesisCare: Employment. Wight:Janssen: Honoraria; Takeda: Honoraria; Abbvie: Honoraria; BMS: Other: Travel; Amgen: Other: Travel. Chong:BMS: Research Funding; Merck Serono: Research Funding; Bayer: Research Funding; Novartis: Research Funding; Hutchison Medipharma: Research Funding; Pharmacyclics: Research Funding. OffLabel Disclosure: Avelumab is an anti-PDL1 monoclonal antibody.

Introduction Anaplastic large-cell lymphoma (ALCL) is a rare subtype of T-cell non-Hodgkin lymphoma, characterized by uniformly strong CD30 expression and further delineated by expression of the Alk protein. Standard first-line (1L) therapy is CHOP-based chemotherapy, with or without consolidative autologous stem cell transplant (ASCT) (Schmitz, Blood, 2010). Despite intensive chemotherapy approaches, 40-65% of patients experience relapsed/refractory disease, for which brentuximab vedotin (BV) as monotherapy has established efficacy (Pro, Blood, 2017) Recent results from ECHELON-2 (E2), led to FDA approval of BV in combination with CHP (CHP+A) as first-line treatment for CD30+ PTCL, based on a 34% reduction in risk of death compared to CHOP, an effect only demonstrable in ALCL (70% of the E2 cohort) (Horwitz, Lancet, 2019). Given this renewed treatment landscape, we investigated outcomes of unselected patients with ALCL treated in routine clinical practice. Methods/Study Population Consecutively diagnosed patients with systemic ALCL from 6 UK and Australian centres (n=166) were studied (Dec 2004-Dec 2018). Patients ≥16 years with ALCL were included irrespective of Alk status. Treatment allocation was clinician choice and included best supportive care (BSC). Post-mortem diagnosis and 10 patients treated on E2 were excluded. Principal outcomes were PFS and OS following 1L treatment. Additional outcome measures included frequency of ASCT and use of BV for r/r ALCL. Data were retrospectively collected following GDPR guidelines and in accordance with the declaration of Helsinki. Results Median age at diagnosis was 57.5 years (range 16-93), 62% were male, 19% had ECOG ≥3 and 53 (35%) patients were ALK positive. Median lines of therapy was 1 (range 0-6). Baseline patient characteristics are shown in table 1. The most frequent 1L treatment regimen was CHOP in 104 pts (67%), 26 (18%) received intensified regimens (CHOEP, CHOP/IVE/MTX, CODOX-M, ALCL99), 4 received other regimens (2.6%) and 14 had best supportive care (9%). Treatment-related mortality was 5.6% (8/142). 12 (8%) patients underwent ASCT in first response, of whom 10 had received intensified induction regimens. Of 141 evaluable pts, ORR was 71% and CR rate was 52%. Median follow up of all patients was 40 months, 3-year PFS and OS for 1L of treatment were 46% and 58% respectively. For the CHOP-treated cohort (n=104), 3-year PFS and OS were 47% and 57%. Outcomes for ALK-negative patients treated with CHOP (n=78) were inferior to ALK-positive; 3-year PFS, OS of 35% and 44% vs 66% and 82% respectively (p=0.003 for both, figure 1). BV was given to 24 pts (15%), mostly for second (16/24) line of therapy. Median doses received were 5 (range 1-14). ORR to BV was 11/24 (45%) and CR rate was 7/24 (30%). Median follow up after BV was 18 months, at which point the PFS and OS rates were 33% and 35% respectively (Figure 1). Bridging to ASCT or alloSCT occurred in 3 and 4 pts respectively, of whom 6 remain alive at data cutoff. 41 patients were staged with both CT and PET-CT, with concordant staging in 63%. 9/41 patients were upstaged by PET, 3 of which resulted in upgraded IPI score (extranodal sites not found on CT). 52 patients had PET-CT after first-line therapy. At data cutoff, 26/35 patients did not progress after PET-defined CR (74%), whereas 6/12 patients progressed after PET-defined PR (50%). Conclusions This study describes a large unselected cohort of ALCL treated in routine clinical practice prior to publication of the E2 study, observing a comparable baseline Alk pos/neg distribution. Notably, survival outcomes of our CHOP-treated cohort are similar to those in the E2 control arm, notwithstanding 28% of our patients with ECOG ≥3 (an E2 exclusion criterion) and also comparable to data from the prospective international T-cell lymphoma project (Shustov, Haematol Oncol, 2019). A minority of pts received intensified regimens and only 8% underwent ASCT consolidation. Achievement of CMR by PET-CT was still associated with a significant proportion of relapses. Outcomes of r/r ALCL treated with single-agent BV were inferior in our cohort as compared to the pivotal Phase 2 data (Pro, Blood, 2017). Our data represent an important benchmark as an unselected ALCL population treated with conventional chemotherapy in routine clinical practice; future studies of CHP+A in the real-world setting will be crucial in assessing the wider impact of the E2 study. Disclosures Martinez-Calle: ABBVIE: Other: Travel support. Manos:Janssen: Honoraria; Novo Nordisk Pharmaceuticals: Other: Travel. Bishton:Takeda: Other: Travel support, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees; Celgene: Research Funding; AbbVie: Research Funding; Celltrion: Membership on an entity's Board of Directors or advisory committees, Other: travel support; Roche: Other: Travel support, Research Funding. Hawkes:Bristol-Myers Squibb: Research Funding, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Mundi pharma: Research Funding; Merck Sharp & Dohme: Membership on an entity's Board of Directors or advisory committees; Roche/Genentech: Membership on an entity's Board of Directors or advisory committees, Other: Travel expenses, Speakers Bureau; Roche: Research Funding; Astra Zeneca: Research Funding; Merck KgA: Research Funding; Janssen-Cilag: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Speakers Bureau. Osborne:Gilead: Consultancy; Pfizer: Honoraria, Speakers Bureau; Takeda: Consultancy, Honoraria, Other: Travel, Speakers Bureau; Novartis: Other: Travel; Servier: Consultancy; MSD: Consultancy; Roche: Consultancy, Honoraria, Other: Travel, Speakers Bureau. Collins:Gilead: Consultancy, Honoraria. Burton:Celgene: Membership on an entity's Board of Directors or advisory committees; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees. Fox:AbbVie: Consultancy; Gilead: Consultancy; Janssen: Consultancy; Celgene: Consultancy; Sunesis: Consultancy; Takeda Pharmaceuticals: Consultancy; Atara Biotherapeutics: Consultancy; Adienne: Other: Travel Support.

Background Primary and secondary central nervous system lymphoma (PCNSL/SCNSL) are rare brain malignancies with an aggressive clinical course and dismal outcomes. The BTK inhibitor ibrutinib has activity in a range of B-cell lymphomas. Phase I and II studies of ibrutinib monotherapy in relapsed/refractory PCNSL have demonstrated promising results, with response rates of up to 81%. Response rates of up to 69% have also been seen in SCNSL. Ibrutinib has been combined with other systemic agents (e.g. rituximab and methotrexate) in phase 1 trials with promising results (Grommes et al Blood 2019); combination with more intensive combination chemotherapy regimens also appears efficacious but has exhibited a potentially limiting toxicity profile, in particular invasive fungal infections. (Lionakis et al Cancer Cell 2017). However, data for ibrutinib in PCNSL and SCNSL outside the clinical trial setting are scarce. Methods We performed a national, multicentre, retrospective study of the clinical outcomes and safety of patients (pts) with PCNSL and SCNSL who received ibrutinib between December 2015 and June 2019. Results The baseline characteristics of the 16 eligible pts are summarised in the table (Figure 1a). 88% (n=14) had relapsed/refractory disease, with two patients receiving ibrutinib as a component of multiagent frontline therapy. The most common target daily dose was 560mg (range 420-840mg); this was reached in all pts. Among all pts, the objective response rate (ORR) was 69%, with a complete remission (CR) rate of 63%. Both patients receiving ibrutinib in combination frontline therapy achieved a CR. ORR in PCNSL pts was 50% (n=4) and SCNSL pts was 88% (n=7), (P=0.28). ORR was 80% (n=4) when ibrutinib was administered as monotherapy, 80% (n=4) when administered with chemotherapy and 75% (n=3) when administered concomitant with whole brain radiotherapy. MYD88L265P mutation at time of starting ibrutinib was only tested in two patients with PCNSL and none with SCNSL. The mutation was detected in both PCNSL cases, and both later attained a CR. With a median follow up of 14 months, calculated using median observation period among patients alive at last follow-up, median progression free survival (PFS) and overall survival (OS) were not reached. 12 month PFS was 56% for the entire cohort (95% confidence interval [CI] 29-76); 50% for PCNSL (95% CI 15-77) and 60% for SCNSL (95% CI 20-85%) (Figure 1b). 12 month OS was 66% for the entire cohort (95% CI 36-85) ; 50% for PCNSL (95% CI 15-77) and 80% for SCNSL (95% CI 20-97%) (Figure 1c). Ten pts had PFS >6 months (longest 41.3 months), and 11 pts (69%) remained alive, with 9/11 being free from disease progression. Seven pts remain on ibrutinib at time of data analysis, 3 with PCNSL and 4 with SCNSL. Nine pts (56%) have discontinued therapy; 6 due to progressive disease (PD), 1 due to atrial fibrillation with hypotension requiring inotropic support and 2 in remission, one of whom subsequently underwent autologous stem cell transplant. Dose interruptions or reductions were required in 6 pts (37%), due to bleeding (n=2), infection (n=3) and neutropenia (n=1). Grade 3/4 adverse events were infection (31%, n=5), neutropenia (25%, n=4), febrile neutropenia (12%, n=2) and one each (6%, n=1) of atrial fibrillation, thrombocytopenia, and anaemia. No invasive fungal infections were observed, despite use of 8-16mg daily dexamethasone immediately prior to or during ibrutinib therapy in 10 pts (62%). Conclusions In this small real-world, majority methotrexate-refractory population, ibrutinib demonstrates encouraging efficacy and durable responses despite doses lower than used in clinical trials. No unexpected adverse events were observed. Invasive fungal infections were not seen, despite most patients receiving concurrent dexamethasone and/or chemotherapy. We observed substantial variety in additional therapy during ibrutinib treatment, and the optimal way to use ibrutinib in this heterogenous patient group remains unclear. Disclosures Manos: NovoNordisk Pharmaceuticals: Other: Travel; Janssen: Honoraria. Ho:Celgene: Consultancy, Other: Advisory role. Grigg:Abbvie: Membership on an entity's Board of Directors or advisory committees; MSD: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Roche: Other: Travel. Gandhi:Amgen: Honoraria; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Honoraria, Research Funding; Roche: Honoraria, Other: Travel Support; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Membership on an entity's Board of Directors or advisory committees. Hawkes:Astra Zeneca: Research Funding; Mundi pharma: Research Funding; Janssen-Cilag: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck KgA: Research Funding; Merck Sharpe & Dohme: Membership on an entity's Board of Directors or advisory committees; Takeda: Speakers Bureau; Bristol-Myers Squibb: Research Funding, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche/Genentech: Membership on an entity's Board of Directors or advisory committees, Other: Travel Expenses, Research Funding, Speakers Bureau. Cheah:Roche: Other: Travel expenses; Roche, Janssen, MSD, Gilead, Loxo Oncology, AstraZeneca, TG Therapeutics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene, Roche, Abbvie: Research Funding. OffLabel Disclosure: Ibrutinib is not currently approved for use in DLBCL/CNS lymphoma.