Abstract: Rituximab, a monoclonal antibody that targets CD20 on B cells, is now central to the treatment of a variety of malignant and autoimmune disorders. Despite this success, a substantial proportion of B-cell lymphomas are unresponsive or develop resistance, hence more potent anti-CD20 monoclonal antibodies (mAbs) are continuously being sought. Here we demonstrate that type II (tositumomab-like) anti-CD20 mAbs are 5 times more potent than type I (rituximab-like) reagents in depleting human CD20 Tg B cells, despite both operating exclusively via activatory Fcγ receptor–expressing macrophages. Much of this disparity in performance is attributable to type I mAb-mediated internalization of CD20 by B cells, leading to reduced macrophage recruitment and the degradation of CD20/mAb complexes, shortening mAb half-life. Importantly, human B cells from healthy donors and most cases of chronic lymphatic leukemia and mantle cell lymphoma, showed rapid CD20 internalization that paralleled that seen in the Tg mouse B cells, whereas most follicular lymphoma and diffuse large B-cell lymphoma cells were far more resistant to CD20 loss. We postulate that differences in CD20 modulation may play a central role in determining the relative efficacy of rituximab in treating these diseases and strengthen the case for focusing on type II anti-CD20 mAb in the clinic.

Abstract: 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.

Abstract: Background: Contemporary trials in adult Ph+ ALL patients with TKIs continue to show improved outcomes with allogeneic blood or marrow transplantation (alloBMT) in first remission (CR1) (Chalandon. Blood. 2015 AND Ravandi. Blood Adv. 2016). These studies have relied on myeloablative conditioning (MAC) and largely required an HLA-matched donor. Post-transplant survival in Ph+ ALL has been shown to be similar between patients transplanted with reduced-intensity conditioning (RIC) and MAC, but the incidence of relapse after RIC is higher (Bachanova. Leukemia. 2014). Post-transplant TKI maintenance reduces the incidence of relapse (Brissot. Haematologica. 2015), but this strategy has not specifically been investigated after RIC. Additionally, HLA-haploidentical donor transplants using post-transplant cyclophosphamide (PTCy) as a component of graft-versus-host disease (GVHD) prophylaxis have comparable outcomes to HLA-matched transplants (McCurdy. Haematologica. 2017). We analyzed outcomes among patients who universally received PTCy and attempted post-transplant TKI prophylaxis to determine the importance of remission status (CR1 vs. later), conditioning regimen, donor type, and TKI choice. Methods: The bone marrow transplant database at Johns Hopkins was queried for adult patients with de novo Ph+ ALL who received alloBMT using PTCy between January 2008 and August 2018. Characteristics of patients were summarized and compared using the student's T test for continuous variables and Fisher's exact test for categorical variables. Estimators of OS and RFS were reported using the Kaplan-Meier method. Differences in time-to-event outcomes were estimated using Cox proportional hazards model. Results: A total of 81 transplants for Ph+ ALL were performed: 69 (85%) in CR1 and 12 (15%) in second or greater remission (CR2+). The demographics are presented in Table 1 and separated by conditioning regimen [MAC vs. nonmyeloablative (NMAC)] for transplants in CR1. The cumulative incidences of grade 2-4 and grade 3-4 aGVHD at 1 year were 33% (95% CI, 23% to 44%) and 9% (95% CI, 3% to 15%), respectively. The incidence of moderate or severe cGVHD at 2 years was 8% (95% CI, 2% to 13%). Nearly all patients (91.4%) initiated a post-transplant TKI at a median of 56 days. Overall, 44.4% of patients were able to take a TKI on ≥85% of nonrelapse days from day 31-395 post-transplant. AlloBMT in CR1 (compared to CR2+) improved RFS (HR=0.25, p=0.0002) and pre-transplant minimal residual disease (MRD) by flow cytometry (MFC) was associated with decreased RFS (HR=2.57, p=0.039). The presence of pre-transplant MRD by PCR did not confer an increased risk of relapse (HR 1.12, p=0.84). Among the 69 patients transplanted in CR1, the 5-year OS was 77.6% (95% CI, 64.8% to 86.2%) and RFS was 67% (95% CI, 52.4-76.5%). As shown in Figure 1, the use of NMAC versus MAC (HR 0.37, p=0.02) and dasatinib versus imatinib at diagnosis (HR 0.21, p=0.007) led to improved relapse-free survival (RFS) in univariate analyses. Neither donor type (with the majority being haploidentical) nor recipient age ≥60 affected RFS. Post-transplant TKI prophylaxis was discontinued prior to relapse in 20 patients among whom 12 remain in an MRD-negative remission, 4 died of non-relapse causes, 3 relapsed, and 1 developed recurrent MRD controlled by a TKI. The median duration of post-transplant TKI prophylaxis prior to discontinuation was 46.5 months in those who remain in treatment-free remission versus 15.6 months in those who relapsed (p=0.01). Eighteen relapses occurred on maintenance therapy, and 90% of tested cases were positive for a kinase domain mutation conferring resistance to the TKI in use at relapse. No significant difference in the median time to TKI initiation post-transplant was noted between those who relapsed on maintenance and those who did not (70 days vs. 55 days, p=0.6). All patients in ongoing remission were MRD-negative by PCR at their most recent evaluation. Conclusions: AlloBMT with PTCy in Ph+ ALL was most effective when performed in CR1 with negative MFC for MRD. The initiation of post-transplant TKI prophylaxis was nearly universal. Among patients transplanted in CR1, the best results were achieved in patients treated with dasatinib at diagnosis (5-year RFS 83%) and NMAC (5-year RFS 73.1%). Thus post-transplant TKI prophylaxis appeared to overcome any relapse control advantage for MAC, yielding better outcomes with NMAC. Disclosures Webster: Amgen: Consultancy; Pfizer: Consultancy. Luznik:WindMil Therapeutics: Patents & Royalties: Patent holder; Genentech: Research Funding; Merck: Research Funding, Speakers Bureau; AbbVie: Consultancy. DeZern:Abbvie: Consultancy; Astex: Research Funding; MEI: Consultancy; Celgene: Consultancy, Honoraria. Pratz:Jazz Pharmaceutical: Consultancy; Millennium: Research Funding; Daiichi Sankyo: Research Funding; Agios: Other: Scientific Advisory Board, Research Funding; Celgene: Other: Scientific Advisory Board; Boston BioMedical: Consultancy; Astellas: Other: Scientific Advisory Board, Research Funding; AbbVie: Other: Scientific Advisory Board, Research Funding. Levis:Astellas: Honoraria, Research Funding; Menarini: Honoraria; Amgen: Honoraria; FujiFilm: Honoraria, Research Funding; Daiichi-Sankyo: Honoraria. Gojo:Amgen: Research Funding; Merck: Research Funding; Genentech: Research Funding; BMS: Membership on an entity's Board of Directors or advisory committees; Amphivena: Research Funding. Bolanos-Meade:Incyte: Other: DSMB Fees. Dalton:Eli Lilly: Research Funding; AbbVie: Research Funding. Jain:Takeda: Consultancy, Honoraria; Bristol Myer Squibb: Other: for advisory board participation; CareDx: Other: Advisory Board. Ali:Celgene: Membership on an entity's Board of Directors or advisory committees. Borrello:Celgene: Research Funding; Aduro: Patents & Royalties; WindMIL Therapeutics: Other: Founder , Research Funding. Wagner-Johnston:ADC Therapeutics, Regeneron, CALIB-R, Verastem: Membership on an entity's Board of Directors or advisory committees. Smith:Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Agios: Consultancy, Membership on an entity's Board of Directors or advisory committees; Jazz: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees.

Abstract: Background: Reduced-intensity induction (RII) with imatinib yields comparable outcomes to HyperCVAD with imatinib with fewer induction deaths and an improved CR rate in Ph+ ALL (Chalandon. Blood. 2015). Dasatinib with steroids also produces excellent responses with little toxicity (Foa. Blood. 2011). Allogeneic bone marrow transplant (AlloBMT) remains the goal of therapy in Ph+ ALL based on contemporary trials with TKIs demonstrating improved survival in patients transplanted in CR1, and we have shown that transplant following induction with dasatinib yields better outcomes than with imatinib. Thus we implemented RII with dasatinib for the treatment of Ph+ ALL and compared to patients who received HyperCVAD with a 2nd generation TKI. Methods: Patients with newly diagnosed Ph+ ALL admitted to Johns Hopkins Hospital from September 2017-June 2020 underwent a 4-week RII with: vincristine 2 mg/d weekly, dexamethasone 40 mg PO weekly on days 1 and 2, and dasatinib 100 mg PO daily. CNS prophylaxis with IT MTX was given on day 8. Dexamethasone and vincristine were reduced by 50% for patients over age 70. Filgrastim was started on day 15 for patients without ANC recovery. Patients who received HyperCVAD with dose adjustments for age (Rausch et al. Cancer. 2020) from July 2011-June 2020 were included for comparison. Dasatinib 100 mg PO daily or nilotinib 400 mg PO BID were given with HyperCVAD at the discretion of the treating physician. Rituximab 375 mg/m^2 on days 1 and 8 was given based on CD20 status. Subsequent therapy after induction was not specifically mandated. Results: 21 patients received RII and 24 received HyperCVAD. The cohorts were comparable in terms of gender (38.1% female vs. 50%, p=0.55), age (median 49.8 vs. 50.3, p=0.33), age & gt;60 (33.3% vs. 29.2%, p & gt;0.99), median WBC at diagnosis (19 vs. 23.5, p=0.56), and the presence of decompensated DIC (fibrinogen & lt;150) prior to treatment initiation (4.8% vs. 8.3%, p & gt;0.99). Among the patients treated with HyperCVAD, 15 received dasatinib (62.5%) and 9 received nilotinib (37.5%). Rituximab use was balanced between the cohorts (61.9% vs. 58.3%, p & gt;0.99). Table 1 compares the time to ANC recovery & gt;500, transfusion requirements within 30 days of chemotherapy initiation, rates of decompensated DIC following treatment initiation, and the duration of inpatient hospitalization for induction. While the rates of decompensated DIC were similar in each cohort, patients treated with RII required fewer platelet and pRBC transfusions. ANC recovery was faster following RII, and only 5 patients (23.8%) received growth factor support. All patients achieved a hematologic response. There was one induction death with HyperCVAD (4.2%). Most patients received a subsequent cycle of high-dose (HD) MTX and Ara-C with TKI (76.2% following RII and 91.7% following HyperCVAD). The remaining patients treated with RII subsequently received HD MTX (14.2%) or blinatumomab (9.5%) with TKI due to co-morbidities. Among those patients treated with HD MTX and Ara-C, blinatumomab was given with TKI to 6 patients (37.5%) who initially received RII and 1 patient (4.5%) after HyperCVAD (p=0.03) due to persistent MRD. As shown in Figure 1, the incidence of MRD-negativity by multi-color flow cytometry (MFC) with a sensitivity of 10-4 at day 120 after treatment initiation was similar for RII (85.4%, 95% CI 64.8-97.1) versus HyperCVAD (86.7%, 95% CI 69.8-96.6). Among patients subsequently treated with HD MTX and Ara-C, 62.5% proceeded to alloBMT after RII with an additional 12.5% currently undergoing transplant evaluation, while 86.4% proceeded to alloBMT after HyperCVAD. The 1-year RFS and OS following RII were 87.9% (95% CI 59.6-96.8) and 100% compared to 87.5% (95% CI 66.1-95.8) and 95.8% (95% CI 73.9-99.4) following HyperCVAD. Conclusion: RII with dasatinib results in fewer transfusions and less myelosuppression compared to HyperCVAD with a 2nd generation TKI. More patients treated with RII received blinatumomab following high-dose MTX and Ara-C, but the rates of MRD-negativity were comparable between the two regimens. Thus RII with dasatinib followed by MRD-guided follow-up therapy facilitates MRD negative remissions with less toxicity than HyperCVAD. The vast majority of fit patients were able to proceed to alloBMT following either regimen. Transplant outcomes following dasatinib with induction are presented in our concurrent abstract demonstrating a 5-year RFS of 83% (95% CI 59.8-93.5). Disclosures Webster: Amgen: Consultancy; Pfizer: Consultancy. Jain:Bristol Myer Squibb: Other: for advisory board participation; CareDx: Other: Advisory Board; Takeda: Consultancy, Honoraria. Dalton:AbbVie: Research Funding; Eli Lilly: Research Funding. DeZern:Abbvie: Consultancy; Astex: Research Funding; Celgene: Consultancy, Honoraria; MEI: Consultancy. Gojo:Genentech: Research Funding; Amphivena: Research Funding; Merck: Research Funding; BMS: Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding. Bolanos-Meade:Incyte: Other: DSMB Fees. Luznik:WindMil Therapeutics: Patents & Royalties: Patent holder; AbbVie: Consultancy; Merck: Research Funding, Speakers Bureau; Genentech: Research Funding. Ali:Celgene: Membership on an entity's Board of Directors or advisory committees. Borrello:Celgene: Research Funding; Aduro: Patents & Royalties; WindMIL Therapeutics: Other: Founder , Research Funding. Wagner-Johnston:ADC Therapeutics, Regeneron, CALIB-R, Verastem: Membership on an entity's Board of Directors or advisory committees. Smith:Jazz: Consultancy, Membership on an entity's Board of Directors or advisory committees; Agios: 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; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees. Levis:Menarini: Honoraria; Amgen: Honoraria; Daiichi-Sankyo: Honoraria; FujiFilm: Honoraria, Research Funding; Astellas: Honoraria, Research Funding.

Abstract: Allogeneic blood or marrow transplantation (alloBMT) is standard of care for adults with Philadelphia chromosome–positive acute lymphoblastic leukemia (Ph+ ALL) in first complete remission (CR1). The routine pretransplant and posttransplant use of tyrosine kinase inhibitors (TKIs) has dramatically improved outcomes, but the optimal conditioning regimen, donor type, and TKI remain undefined. The bone marrow transplant database at Johns Hopkins was queried for adult patients with de novo Ph+ ALL who received alloBMT using posttransplantation cyclophosphamide (PTCy) as a component of graft-versus-host disease (GVHD) prophylaxis from 2008 to 2018. Among transplants for Ph+ ALL, 69 (85%) were performed in CR1, and 12 (15%) were performed in second or greater remission (CR2+). The majority of transplants (58%) were HLA haploidentical. Nearly all patients (91.4%) initiated TKI posttransplant. For patients in CR1, the 5-year relapse-free survival (RFS) was 66%. The use of nonmyeloablative conditioning, absence of measurable residual disease (MRD) according to flow cytometry at transplant, and the use of dasatinib vs imatinib at diagnosis were associated with improved overall survival (OS) and RFS. Neither donor type nor recipient age ≥60 years affected RFS. When analyzing all transplants, alloBMT in CR1 (vs CR2+) and the absence of pretransplant MRD were associated with improved RFS. Most relapses were associated with the emergence of kinase domain mutations. The cumulative incidence of grade 3 to 4 acute GVHD at 1 year was 9%, and moderate to severe chronic GVHD at 2 years was 8%. Nonmyeloablative alloBMT with PTCy for Ph+ ALL in an MRD-negative CR1 after initial treatment with dasatinib yields favorable outcomes.

Abstract: Introduction DLBCL is the most common lymphoid neoplasm in adults (Swerdlow 2016). While durable CRs are achieved in approximately 70% of patients (pts) with frontline RCHOP therapy (Pfreundschuh 2008), pts with high-risk features often experience disease resistance or relapse. In Part 1 of an ongoing study, pts with high-intermediate or high risk DLBCL by international prognostic index (IPI) scores, regardless of CD30 expression by IHC, were treated with 1.2 or 1.8 mg/kg brentuximab vedotin (BV) combined with RCHOP. After 3 of the first 10 pts treated at 1.8 mg/kg BV+RCHOP developed Grade 3 peripheral neuropathy (per Standardized MedDRA Query [SMQ]), all pts enrolled subsequently received treatment with 1.2 mg/kg BV+RCHOP. Following completion of enrollment in Part 1, the protocol was amended to enroll a non-randomized portion of the study (Part 2) evaluating the safety and efficacy of 1.8 mg/kg BV+RCHP (Yasenchak 2015), followed by an open-label, randomized portion comparing BV+RCHP to RCHOP (Part 3). Initial results from Part 2 and updated results from Part 1 are reported here. Methods For Part 2 of the study, pts with CD30-expressing high-intermediate and high-risk DLBCL were treated with up to 6 cycles of 1.8 mg/kg BV+RCHP (NCT01925612). Key inclusion criteria were CD30 expression by IHC performed by a local pathology lab and standard IPI scores of 3-5 or age-adjusted IPI (aaIPI) scores of 2-3 (high-intermediate/high risk). CD30 expression was confirmed by a central pathology lab, although CD30 expression by local pathology lab was required for eligibility. Disease response was evaluated with PET/CT per Cheson 2007. Results At the time of analysis for this ongoing study, 11 pts in Part 2 were treated with BV+RCHP (7 male, 4 female; 22-78 yrs). Of these pts, 9 had high-intermediate risk (IPI 3, aaIPI 2) and 2 had high risk disease (IPI 4-5, aaIPI 3), 6 had Stage IV disease, and 6 had an ECOG score of 2. At the end of treatment, the overall response rate was 91% (9 CR, 1 PR); 1 pt had PD after Cycle 4. The most frequent ( 〉 20%) treatment-emergent adverse events (AEs) were alopecia and nausea (73% each); fatigue (64%); constipation and peripheral sensory neuropathy (55% each); neutropenia and throat irritation (36% each); and chills, diarrhea, headache, and stomatitis (27% each). Grade 3 or 4 AEs occurred in 8 pts and 5 pts had serious AEs, which included febrile neutropenia, bacteremia, nausea, pneumocystis jiroveci pneumonia, pulmonary embolism, and vomiting. Peripheral sensory neuropathy occurred in 6 pts and all were Grade 1 or 2 events; no peripheral motor neuropathy AEs were reported. No AEs were fatal or led to discontinuation. One pt discontinued treatment after Cycle 4 due to disease progression. For the first 51 pts in Part 1, the progression-free survival (PFS) at 18 months for pts with CD30 expression (25 pts) or without detectable CD30 expression (24 pts) by IHC was 79% (95% CI: 57%, 91%) versus 58% (95% CI: 36%, 75%), respectively. Overall survival for pts was 92% (95% CI: 71%, 98%) versus 71% (95% CI: 48%, 85%), respectively. Ten pts had pre-existing peripheral neuropathy (per SMQ) at study entry. Treatment-emergent peripheral neuropathy (per SMQ) was observed in 75% of pts (38/51) who received BV+RCHOP; 55% of these pts (21/38) had resolution of all or some peripheral neuropathy events. Conclusions 1.8 mg/kg BV+RCHP is active as frontline treatment in CD30-expressing, high-intermediate/high risk DLBCL. When combined with RCHP, 1.8 mg/kg BV appears to be well-tolerated. The PFS and OS for pts with CD30-expression who received BV+RCHOP appear promising. The study is currently ongoing in pts with CD30-expressing high-intermediate/high risk DLBCL to assess the safety and activity of 1.8 mg/kg BV+RCHP versus standard RCHOP. Disclosures Halwani: Bristol Myers-Squibb: Research Funding; Kyowa Hakko Kirin: Research Funding; Takeda: Research Funding; Genentech: Research Funding; AbbVie: Consultancy, Other: Travel Expenses, Research Funding; Seattle Genetics: Consultancy, Research Funding; Immune Design: Research Funding; Miragen: Research Funding; Pharmacyclics: Consultancy; Amgen: Research Funding. Yasenchak:Seattle Genetics: Research Funding. Farber:Seattle Genetics: Research Funding. Burke:Pfizer: Consultancy; Janssen: Consultancy; Incyte: Consultancy; TG Therapeutics: Other: Travel Expenses; Millenium: Consultancy. Fayad:Seattle Genetics: Consultancy, Research Funding. Holkova:Seattle Genetics: Research Funding. Knapp:Insys Therapeutics, Inc.: Consultancy, Other: Travel, Accommodations, Expenses; Pharmacyclics, LLC, an AbbVie Company: Consultancy, Other: Travel, Accommodations, Expenses, Research Funding. Kolibaba:Gilead: Consultancy, Research Funding; Celgene: Research Funding; TG Therapeutics: Research Funding; Takeda Pharmaceuticals International Co.: Research Funding; Seattle Genetics: Research Funding; Pharmacyclics: Research Funding; janssen: Research Funding; GSK: Research Funding; Genentech: Research Funding; Acerta: Research Funding. Patel-Donnelly:Seattle Genetics: Research Funding. Yimer:Ariad Pharmaceuticals: Consultancy; Biotheranostics: Consultancy; Bluebird Bio: Equity Ownership; Kite Pharma: Equity Ownership; Clovis Oncology: Equity Ownership; Juno Therpeutics: Equity Ownership; Seattle Genetics: Research Funding. Smith:Celgene: Consultancy, Speakers Bureau; Seattle Genetics: Research Funding. Levy:Janssen: Speakers Bureau; Amgen: Speakers Bureau; Takeda Pharmaceuticals International Co.: Speakers Bureau; Seattle Genetics: Research Funding; Actinium Pharmaceuticals, Inc.: Research Funding. Seetharam:Seattle Genetics: Research Funding. Belada:Seattle Genetics: Research Funding. Brooks:Seattle Genetics: Research Funding. Kingsley:Gilead: Equity Ownership; Pharmacyclics LLC, an AbbVie Company: Equity Ownership. Wagner-Johnston:Seattle Genetics: Research Funding. Ruffner:Forma Therapeutics: Consultancy; Sydnax: Consultancy; Seattle Genetics: Employment, Equity Ownership; Array Biopharma: Employment; Medivation: Employment. Bartlett:Gilead: Consultancy.

Abstract: Background: The benefit of allogeneic blood or marrow transplantation (alloBMT) following myeloablative conditioning (MAC) in first complete remission (CR1) compared to chemotherapy has been demonstrated in a randomized trial for adults with acute lymphoblastic leukemia (ALL). Persistence of measurable residual disease (MRD) prior to alloBMT confers an increased risk of relapse. Blinatumomab eradicates persistent or recurrent MRD at levels ≥10 -3 in 78% of B ALL. However, post-hoc analyses of patients who have undergone alloBMT following blinatumomab for MRD demonstrate non-relapse mortality (NRM) of 36.5%. NRM following nonmyeloablative (NMAC) alloBMT with high-dose post-transplantation cyclophosphamide (PTCy) is just 11%. Given broadly similar outcomes between HLA-matched MAC alloBMT and HLA-haploidentical NMAC alloBMT following PTCy, we have shifted to using exclusively NMAC alloBMT with PTCy and sought to explore outcomes depending on receipt of pre-transplant blinatumomab. Methods: The bone marrow transplant database at Johns Hopkins was queried for adult patients with Ph-negative B-ALL who received NMAC alloBMT in CR1 using PTCy between January 2008 and July 2020. Characteristics of patients were summarized and compared using the student's T test for continuous variables and Fisher's exact test for categorical variables. Estimators of OS and RFS were reported using the Kaplan-Meier method. Differences in time-to-event outcomes were estimated using Cox proportional hazards model for OS and RFS, and Fine and Gray's model for cumulative incidence of relapse (CIR)/NRM considering competing events. Results: Among the 50 identified patients undergoing 1 st transplant in CR1 with NMAC, all received conditioning with fludarabine and cyclophosphamide followed by total body irradiation (TBI). In addition to PTCy, all patients received mycophenolate mofetil and either tacrolimus or sirolimus as GVHD prophylaxis. Sixteen patients (32%) received blinatumomab in CR1 or achieved CR1 following blinatumomab and proceeded to transplant without intervening therapy, while 34 patients (68%) did not. At the time of treatment with blinatumomab; 3 patients had & gt;5% blasts after chemotherapy, 8 had persistent or recurrent MRD & gt;10 -4 after chemotherapy, and 5 had no evidence of MRD at a sensitivity of 10 -4. Among the 5 MRD- patients treated with blinatumomab; 1 had been refractory to their first course of chemotherapy (67% blasts), 3 had MRD & gt;10 -4 at the first MRD response assessment following chemotherapy, and 1 had CNS involvement at diagnosis. The demographics of these two groups are presented in Table 1 and separated by pre-transplant blinatumomab status. The groups were well balanced in terms of gender, age, WBC at diagnosis, CNS involvement at diagnosis, and donor type. Patients who received blinatumomab were more likely to have been refractory to their initial course of chemotherapy and were transplanted later after their initial diagnosis than those who did not. All patients who received blinatumomab were MRD-negative at a sensitivity of 10 -4 prior to their transplant, while 11.8% of patients who did not receive blinatumomab were MRD-positive. Relapse-free and overall survival, cumulative incidence of relapse, and non-relapse mortality by receipt of blinatumomab prior to transplant are shown in Figure 1. Non-relapse mortality was not increased among patients who received pre-transplant blinatumomab (HR=1.06, p=0.94). The causes of non-relapse mortality included GVHD (1) and secondary malignancy (1) in patients who received blinatumomab; and infection (1), bleeding (1), secondary malignancy (1), and other (1) in patients who did not receive blinatumomab. Receipt of pre-transplant blinatumomab was associated with a decreased cumulative incidence of relapse (HR=0.15, p=0.07) and improved relapse-free survival (HR=0.32, p=0.07). Overall survival (HR=0.63, p=0.5) between the two groups was similar, likely reflecting the efficacy of salvage therapies such as CD19 CAR T cells; blinatumomab; and inotuzumab in the relapsed, post-transplant population. Conclusions: Treatment with blinatumomab prior to NMAC alloBMT with PTCy in CR1 for Ph-negative B ALL did not increase NRM and produced a 3-year RFS of 81%. The low CIR and NRM of NMAC alloBMT in an MRD-negative CR1 following blinatumomab suggest it could be a viable alternative to MAC. Figure 1 Figure 1. Disclosures Webster: AmGen: Consultancy; Pfizer: Consultancy. DeZern: Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees; Taiho: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Consultancy, Membership on an entity's Board of Directors or advisory committees. Levis: Takeda: Honoraria; BMS: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy, Honoraria; Jazz: Consultancy, Honoraria; Astellas and FujiFilm: Research Funding; Amgen, Astellas Pharma, Daiichi-Sankyo, FujiFilm, and Menarini: Honoraria; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Ghiaur: Syros Pharmaceuticals: Consultancy; Menarini Richerche: Research Funding. Hourigan: Sellas: Research Funding. Jain: Syneos Health: Research Funding; CTI Biopharma: Research Funding; CareDx: Other: for advisory board participation; Bristol Myers Squibb: Other: for advisory board participation; Targeted Healthcare Communications: Consultancy. Ali: Janssen: Consultancy; BMS: Consultancy; Oncopeptides: Consultancy; Sanofi: Consultancy; Amgen: Consultancy; Aduro: Consultancy; Poseida: Research Funding; Aduro: Research Funding; BMS: Research Funding.