Consensus recommendations on the management of toxicity associated with CD3×CD20 bispecific antibody therapy

ABSTRACT

Bispecific antibodies (BsAb) that target CD3 and CD20 represent a new milestone in the treatment of patients with B-cell non-Hodgkin lymphoma. These drugs have demonstrated remarkable single-agent activity in patients with heavily pretreated disease, and 3 drugs have so far received regulatory approvals in various countries. However, BsAbs can potentially lead to severe toxicity associated with T-cell activation, particularly cytokine release syndrome (CRS). The anticipated widespread use of these off-the-shelf products poses challenges for implementation and highlights the need for guidance in anticipating, mitigating, and managing adverse events. In clinical trials, guidance for the evaluation and treatment of CRS and neurotoxicity associated with BsAb therapy has been modeled after algorithms originally created for chimeric antigen receptor (CAR) T-cell therapies and other immune effector therapies, yet notable differences in timing, quality, and severity exist between the toxicities of BsAbs and CAR T-cell therapies. We therefore convened an international panel of academic and community practice physicians, advanced practitioners, registered nurses, and pharmacists with experience using CD3×CD20 BsAbs in clinical trial and off-trial settings to provide comprehensive, consensus-based recommendations specific to the assessment and management of CD3×CD20 BsAb-related toxicities.

Mosunetuzumab Safety Profile in Patients With Relapsed/Refractory B-cell Non-Hodgkin Lymphoma: Clinical Management Experience From a Pivotal Phase I/II Trial

BACKGROUND

Mosunetuzumab is a CD20xCD3 T-cell engaging bispecific antibody approved in Europe and the United States for relapsed/refractory (R/R) follicular lymphoma (FL) after ≥ 2 prior therapies.

MATERIALS AND METHODS

We present interim safety data from the mosunetuzumab GO29781 (NCT02500407) phase I/II dose-escalation study in R/R non-Hodgkin lymphoma (NHL), focusing on FL.

RESULTS

Overall, 218 patients with R/R NHL, including 90 with R/R FL, received a median of eight 21-day cycles of intravenous mosunetuzumab with step-up dosing in Cycle (C) 1 (C1 Day [D] 1, 1 mg; C1D8, 2 mg; C1D15/C2D1, 60 mg; C3D1 and onwards, 30 mg). Cytokine release syndrome (CRS) was the most common adverse event (AE), occurring in 39.4% (NHL) and 44.4% (FL) of patients. Events occurred predominantly during C1 at the first loading dose; the majority were grade 1/2. CRS events were managed at the investigator's discretion with supportive care, steroids, and tocilizumab, based on protocol management guidelines. Immune effector cell-associated neurotoxicity syndrome was uncommon, reported in 0.9% (NHL) and 1.1% (FL) of patients. Neutropenia occurred in 27.5% (NHL) and 28.9% (FL) of patients (mostly grade 3/4) and could be effectively managed using granulocyte colony-stimulating factor. Tumor lysis syndrome occurred in 0.9% (NHL) and 1.1% (FL) of patients (all grade 3/4 with CRS; all resolved).

CONCLUSION

Mosunetuzumab monotherapy as treatment for R/R B-cell NHL, including FL, was associated with low rates of severe AEs (including CRS) and is suitable for outpatient administration in the community setting. Adapted protocol guidance for the management of select AEs during mosunetuzumab treatment is included.

Mosunetuzumab monotherapy is active and tolerable in patients with relapsed/refractory diffuse large B-cell lymphoma

As part of a phase 1 or 2 study, this single-arm expansion cohort established the efficacy and safety of mosunetuzumab monotherapy in patients with relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL) (received ≥2 previous lines of therapy). Intravenous mosunetuzumab was administered with cycle (C) 1 step-up dosing for cytokine release syndrome (CRS) mitigation: C1 day (D) 1: 1 mg; C1D8 2 mg; C1D15 and C2D1: 60 mg; C3 + D1: 30 mg. Hospitalization was not mandatory. Patients with complete response (CR) completed treatment after C8; those with partial response or stable disease continued treatment for a total of 17 cycles. The primary end point was CR rate (best response), assessed against a historical control CR rate (20%) by independent review facility. Eighty-eight patients (73.9% de novo DLBCL; 26.1% transformed follicular lymphoma) were enrolled; all had received previous anthracycline and anti-CD20 therapy. Overall response and CR rates were 42.0% (95% confidence interval [CI], 31.6-53.1) and 23.9% (95% CI, 15.4-34.1), respectively; CR rate did not reach statistical significance vs the historical control (P = .36). Median time to first response was 1.4 months. Median progression-free survival was 3.2 months (95% CI, 2.2-5.3). The CR rate in 26 patients who received previous chimeric antigen receptor T-cell (CAR-T) therapy was 12%. CRS was one of the most common adverse events (26.1% of patients); predominantly grade 1 to 2 and primarily in C1. Four patients (4.5%) discontinued mosunetuzumab owing to adverse events. Mosunetuzumab demonstrated notable efficacy and a manageable safety profile in patients with R/R DLBCL, including those previously treated with CAR-Ts. This trial was registered at www.clinicaltrials.gov as #NCT02500407.

Phase I Study of Acalabrutinib Plus Danvatirsen (AZD9150) in Relapsed/Refractory Diffuse Large B-Cell Lymphoma Including Circulating Tumor DNA Biomarker Assessment

PURPOSE

Novel targeted and immunotherapies have improved outcomes in relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL), but toxicities limit widespread use. The selective Bruton tyrosine kinase (BTK) inhibitor acalabrutinib has activity in patients with R/R DLBCL but durable responses are uncommon. STAT3 inhibition has demonstrated clinical activity in DLBCL.

PATIENTS AND METHODS

Final results of the phase I study of acalabrutinib plus STAT3 inhibitor (danvatirsen; AZD9150) in patients with R/R DLBCL are reported. Danvatirsen 200 mg intravenous infusion [Days 1, 3, 5 (Cycle 1); weekly infusions starting Day 8, Cycle 1] was administered in combination with oral acalabrutinib 100 mg twice daily until progressive disease (PD) or unacceptable toxicity. Primary endpoints were safety and tolerability. Secondary endpoints included efficacy, pharmacokinetics, and immunogenicity.

RESULTS

Seventeen patients received combination treatment. One dose-limiting toxicity (Grade 3 liver transaminase) occurred in 1 patient. The most common reason for treatment discontinuation was PD (65%). In evaluable patients (n = 17), objective response rate was 24%; median duration of response was 1.9 months. All responders with available DLBCL cell-of-origin data were either activated B-cell or nongerminal center B-cell like subtype. Genetic subtype did not correlate with response. Baseline and longitudinal plasma cell-free DNA (cfDNA) concentrations were mostly higher in nonresponding patients. cfDNA changes were generally concordant with imaging. Pretreatment circulating B-cell levels were higher in responders versus nonresponders.

CONCLUSIONS

Targeting both STAT3 and BTK in combination is safe and tolerable but efficacy is limited in R/R DLBCL. Results support evaluation of circulating tumor DNA as a biomarker for clinical response.

Pirtobrutinib in Covalent Bruton Tyrosine Kinase Inhibitor Pretreated Mantle-Cell Lymphoma

PURPOSE

Pirtobrutinib is a highly selective, noncovalent (reversible) Bruton tyrosine kinase inhibitor (BTKi). We report the safety and efficacy of pirtobrutinib in patients with covalent Bruton tyrosine kinase inhibitor (cBTKi) pretreated mantle-cell lymphoma (MCL), a population with poor prognosis.

METHODS

Patients with cBTKi pretreated relapsed/refractory (R/R) MCL received pirtobrutinib monotherapy in a multicenter phase I/II trial (BRUIN; ClinicalTrials.gov identifier: NCT03740529). Efficacy was assessed in the first 90 consecutively enrolled patients who met criteria for inclusion in the primary efficacy cohort. The primary end point was overall response rate (ORR). Secondary end points included duration of response (DOR) and safety.

RESULTS

The median patient age was 70 years (range, 46-87), the median prior lines of therapy was 3 (range, 1-8), 82.2% had discontinued a prior cBTKi because of disease progression, and 77.8% had intermediate- or high-risk simplified MCL International Prognostic Index score. The ORR was 57.8% (95% CI, 46.9 to 68.1), including 20.0% complete responses (n = 18). At a median follow-up of 12 months, the median DOR was 21.6 months (95% CI, 7.5 to not reached). The 6- and 12-month estimated DOR rates were 73.6% and 57.1%, respectively. In the MCL safety cohort (n = 164), the most common treatment-emergent adverse events (TEAEs) were fatigue (29.9%), diarrhea (21.3%), and dyspnea (16.5%). Grade ≥3 TEAEs of hemorrhage (3.7%) and atrial fibrillation/flutter (1.2%) were less common. Only 3% of patients discontinued pirtobrutinib because of a treatment-related adverse event.

CONCLUSION

Pirtobrutinib is a first-in-class novel noncovalent (reversible) BTKi and the first BTKi of any kind to demonstrate durable efficacy after prior cBTKi therapy in heavily pretreated R/R MCL. Pirtobrutinib was well tolerated with low rates of treatment discontinuation because of toxicity.

The impact of early versus late tocilizumab administration in patients with cytokine release syndrome secondary to immune effector cell therapy

INTRODUCTION

Cytokine release syndrome is a life-threatening hyper-inflammatory state induced by immune effector cell therapy. Anti-interleukin 6-(IL-6) therapy, such as tocilizumab, is the standard treatment for cytokine release syndrome since it reverses symptoms without compromising immune effector cell therapy efficacy. Glucocorticoids are reserved for refractory or severe cytokine release syndrome due to concern for attenuating antitumor activity. Optimizing the timing of tocilizumab could avoid glucocorticoid use and improve outcomes. This study assesses tocilizumab timing on patient outcomes and healthcare resource utilization.

METHODS

This is a retrospective single-institution analysis of 28 patients who received tocilizumab for cytokine release syndrome secondary to immune effector cell therapy. Patients were categorized into two groups: Early Tocilizumab (within 24 h) or Late Tocilizumab groups (more than 24 h) from fever onset. The composite primary endpoint was glucocorticoid use, intensive care unit admission, or inpatient mortality. Secondary outcomes include comparing the various presentations of cytokine release syndrome, need for vasopressors, length of stay, rates of neurotoxicity, and C-reactive protein and ferritin trends.

RESULTS

The Early Tocilizumab group presented with more rapid fever onset (35 vs.113 h, P = 0.017) and higher maximum cytokine release syndrome grade (Median, Grade 2 vs. Grade 1, P = 0.025). Additionally, the Early Tocilizumab group required more doses of tocilizumab (Median, 2 vs. 1, P = 0.037). Despite the difference in cytokine release syndrome presentation, the primary composite endpoint was not statistically different between groups.

CONCLUSION

Earlier onset of fever appears to be associated with more severe, progressive cytokine release syndrome requiring multiple doses of anti-interleukin-6 therapy. Prompt and aggressive tocilizumab treatment could be protective against the negative consequences of cytokine release syndrome.

Abstract CT125: A phase 1/2 randomized study of IGM-2323 in relapsed/refractory non-Hodgkin lymphomas

Background: Recent advances in the treatment of non-Hodgkin lymphoma (NHL) have transformed the landscape and provided significant benefits to patients. Novel agents that target CD19 and CD20 on B cells, such as bispecific T-cell engagers and chimeric antigen receptor (CAR) T cell therapy, have demonstrated benefit for patients in the relapsed and refractory setting. However, these agents can often be associated with significant toxicity and there is a need for new therapies that can provide clinical benefit while providing an improved safety profile.IGM-2323 is a novel CD20 x CD3 bispecific antibody utilizing an IgM backbone. This allows targeting of up to 10 CD20 binding sites for every CD3 site. In preclinical models, IGM-2323 demonstrated excellent antitumor activity with controlled T-cell activation. IGM-2323 is able to stimulate T cells at a more physiologic level than IgG-based antibodies, which may reduce adverse events typically associated with T-cell engagers and CAR-T, such as CRS and neurotoxicity.

Methods: This study is a phase 1/2, multicenter, single-arm clinical trial of IGM-2323 monotherapy for patients with relapsed/refractory NHL. The Phase 1 component consists of a dose escalation and limited dose expansion evaluating multiple titration dose levels. As part of the titration dosing regimen, subjects receive weekly dosing on Day 1, 8, and 15 of each 21- day cycle. Dosing begins at 15 mg and is increased weekly for 3-4 weeks to reach the plateau dose. Patients then stay at the plateau dose until disease progression or unacceptable toxicity. Patients who achieve a response by Week 12 may switch to a less frequent dosing interval of every 3 weeks. The Phase 2 component will randomize patients at two different dose levels (100 mg and 300 mg plateau dose) in two separate indications (R/R DLBCL and R/R FL). Primary endpoints include frequency and severity of adverse events and objective response rate (ORR) based on Lugano criteria. Correlative biomarker studies will evaluate the correlation of clinical benefit with blood and tissue biomarkers. In Phase 2, there will be a formal analysis after 30 subjects are evaluable at each dose level and the best dose for each indication will be selected for further evaluation. The study is currently open with 47 patients enrolled at time of submission. Phase 2 is expected to begin enrollment in the first quarter of 2022. Clinical trial information: NCT04082936.

Citation Format: Loretta Nastoupil, Elizabeth Budde, Won Seog Kim, Ajay Gopal, Chan Cheah, Ian Flinn, Gareth Gregory, Matthew Matasar, Catherine Diefenbach, Matthew Ku, Sung-Soo Yoon, Ibrahim Qazi, Rachel Wei, Maya Leabman, Genevive Hernandez, Iris Sison, Bruce Keyt, Thomas Manley, Phillipe Armand. A phase 1/2 randomized study of IGM-2323 in relapsed/refractory non-Hodgkin lymphomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT125.

Second-Line Tisagenlecleucel or Standard Care in Aggressive B-Cell Lymphoma

BACKGROUND

Patient outcomes are poor for aggressive B-cell non-Hodgkin's lymphomas not responding to or progressing within 12 months after first-line therapy. Tisagenlecleucel is an anti-CD19 chimeric antigen receptor T-cell therapy approved for diffuse large B-cell lymphoma after at least two treatment lines.

METHODS

We conducted an international phase 3 trial involving patients with aggressive lymphoma that was refractory to or progressing within 12 months after first-line therapy. Patients were randomly assigned to receive tisagenlecleucel with optional bridging therapy (tisagenlecleucel group) or salvage chemotherapy and autologous hematopoietic stem-cell transplantation (HSCT) (standard-care group). The primary end point was event-free survival, defined as the time from randomization to stable or progressive disease at or after the week 12 assessment or death. Crossover to receive tisagenlecleucel was allowed if a defined event occurred at or after the week 12 assessment. Other end points included response and safety.

RESULTS

A total of 322 patients underwent randomization. At baseline, the percentage of patients with high-grade lymphomas was higher in the tisagenlecleucel group than in the standard-care group (24.1% vs. 16.9%), as was the percentage with an International Prognostic Index score (range, 0 to 5, with higher scores indicating a worse prognosis) of 2 or higher (65.4% vs. 57.5%). A total of 95.7% of the patients in the tisagenlecleucel group received tisagenlecleucel; 32.5% of the patients in the standard-care group received autologous HSCT. The median time from leukapheresis to tisagenlecleucel infusion was 52 days. A total of 25.9% of the patients in the tisagenlecleucel group had lymphoma progression at week 6, as compared with 13.8% of those in the standard-care group. The median event-free survival in both groups was 3.0 months (hazard ratio for event or death in the tisagenlecleucel group, 1.07; 95% confidence interval, 0.82 to 1.40; P = 0.61). A response occurred in 46.3% of the patients in the tisagenlecleucel group and in 42.5% in the standard-care group. Ten patients in the tisagenlecleucel group and 13 in the standard-care group died from adverse events.

CONCLUSIONS

Tisagenlecleucel was not superior to standard salvage therapy in this trial. Additional studies are needed to assess which patients may obtain the most benefit from each approach. (Funded by Novartis; BELINDA ClinicalTrials.gov number, NCT03570892.).

Ibrutinib Plus Venetoclax for First-Line Treatment of Chronic Lymphocytic Leukemia: Primary Analysis Results From the Minimal Residual Disease Cohort of the Randomized Phase II CAPTIVATE Study

PURPOSE

CAPTIVATE (NCT02910583), a randomized phase II study, evaluates minimal residual disease (MRD)-guided treatment discontinuation following completion of first-line ibrutinib plus venetoclax treatment in patients with chronic lymphocytic leukemia (CLL).

METHODS

Previously untreated CLL patients age < 70 years received three cycles of ibrutinib and then 12 cycles of combined ibrutinib plus venetoclax. Patients in the MRD cohort who met the stringent random assignment criteria for confirmed undetectable MRD (Confirmed uMRD) were randomly assigned 1:1 to double-blind placebo or ibrutinib; patients without Confirmed uMRD (uMRD Not Confirmed) were randomly assigned 1:1 to open-label ibrutinib or ibrutinib plus venetoclax. Primary end point was 1-year disease-free survival (DFS) rate with placebo versus ibrutinib in the Confirmed uMRD population. Secondary end points included response rates, uMRD, and safety.

RESULTS

One hundred sixty-four patients initiated three cycles of ibrutinib lead-in. After 12 cycles of ibrutinib plus venetoclax, best uMRD response rates were 75% (peripheral blood) and 68% (bone marrow). Patients with Confirmed uMRD were randomly assigned to receive placebo (n = 43) or ibrutinib (n = 43); patients with uMRD Not Confirmed were randomly assigned to ibrutinib (n = 31) or ibrutinib plus venetoclax (n = 32). Median follow-up was 31.3 months. One-year DFS rate was not significantly different between placebo (95%) and ibrutinib (100%; arm difference: 4.7% [95% CI, -1.6 to 10.9]; P = .15) in the Confirmed uMRD population. After ibrutinib lead-in tumor debulking, 36 of 40 patients (90%) with high tumor lysis syndrome risk at baseline shifted to medium or low tumor lysis syndrome risk categories. Adverse events were most frequent during the first 6 months of ibrutinib plus venetoclax and generally decreased over time.

CONCLUSION

The 1-year DFS rate of 95% in placebo-randomly assigned patients with Confirmed uMRD suggests the potential for fixed-duration treatment with this all-oral, once-daily, chemotherapy-free regimen in first-line CLL.

A phase 1/2 study of the combination of acalabrutinib and vistusertib in patients with relapsed/refractory B-cell malignancies

In a phase 1b study of acalabrutinib (a covalent Bruton tyrosine kinase (BTK) inhibitor) in combination with vistusertib (a dual mTORC1/2 inhibitor) in patients with relapsed/refractory diffuse large B-cell lymphoma (DLBCL), multiple ascending doses of the combination as intermittent or continuous schedules of vistusertib were evaluated. The overall response rate was 12% (3/25). The pharmacodynamic (PD) profile for acalabrutinib showed that BTK occupancy in all patients was >95%. In contrast, PD analysis for vistusertib showed variable inhibition of phosphorylated 4EBP1 (p4EBP1) without modulation of AKT phosphorylation (pAKT). The pharmacokinetic (PK)/PD relationship of vistusertib was direct for TORC1 inhibition (p4EBP1) but did not correlate with TORC2 inhibition (pAKT). Cell-of-origin subtyping or next-generation sequencing did not identify a subset of DLBCL patients with clinical benefit; however, circulating tumor DNA dynamics correlated with radiographic response. These data suggest that vistusertib does not modulate targets sufficiently to add to the clinical activity of acalabrutinib monotherapy. Clinicaltrials.gov identifier: NCT03205046.

Preliminary results of the phase 2 study of zanubrutinib in patients with previously treated B-cell malignancies intolerant to ibrutinib and/or acalabrutinib

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Background: Many patients (pts) with B-cell malignancies require continuous treatment with Bruton tyrosine kinase inhibitors (BTKi). Adverse events (AEs) are a common reason for ibrutinib (ibr) or acalabrutinib (acala) discontinuation. Early data from BGB-3111-215 showed zanubrutinib (zanu) was well tolerated in pts with B-cell malignancies intolerant to ibr or acala. We report preliminary results with a median follow-up of 4.2 mo. Methods: Pts meeting protocol criteria for intolerance to ibr, acala or both (without documented progressive disease) were given zanu monotherapy (160 mg twice daily or 320 mg once daily). Recurrence of AEs that led to intolerance of prior BTKi and additional safety measures were assessed based on the Common Terminology Criteria for AEs v5.0. Investigators determined responses using disease status at study entry as baseline. Results: As of November 1, 2020 (cutoff), 44 pts (n=34 chronic lymphocytic leukemia/small lymphocytic lymphoma, n=6 Waldenström macroglobulinemia, n=2 mantle cell lymphoma, n=2 marginal zone lymphoma) were enrolled, received ≥1 dose of zanu, and analyzed for safety. Median age was 70.5 y (range, 49-91); median duration of treatment was 4.2 mo (range, 0.1-12.6). Median number of prior regimens was 2 (range, 1-12). Regarding prior BTKi, 39 pts received ibr only, 4 received ibr and acala, and 1 received acala only. The median number of ibr- or acala-intolerant AEs per pt was 2 (range, 1-5). 83% of ibr and 78% of acala intolerant events did not reccur on zanu; Table. At data cutoff, 43 pts remained on treatment; 1 withdrew consent due to zanu-unrelated grade 3 syncope. Overall, 34 pts (77.3%) reported any AE; most commonly reported AEs were myalgia (n=9; 20.5%), contusion (n=8; 18.2%), dizziness (n=7; 15.9%), fatigue (n=7; 15.9%), and cough (n=5; 11.4%). Grade ≥3 AEs were reported in 6 pts (13.6%), serious AEs in 1 pt (2.3%, febrile neutropenia and salmonella infection), AEs requiring dose interruptions in 6 pts (13.6%), and AEs leading to dose reduction in 2 pts (4.5%). No AEs led to zanu discontinuation. No deaths were reported. All efficacy evaluable pts (26/26 [100%]) maintained (10 [38.5%]) or achieved deepening (16 [61.5%]) of their response. Conclusions: Zanu provides an additional treatment option after intolerance to other BTKi, demonstrating tolerability and sustained or improved efficacy. Updated results will be presented. Recurrence and Severity Change of AEs Leading to Ibr or Acala Intolerance. Clinical trial information: NCT04116437. [Table: see text]

Outcomes with KTE-X19 in patients (pts) with relapsed/refractory (R/R) mantle cell lymphoma (MCL) in ZUMA-2 who had progression of disease within 24 months of diagnosis (POD24)

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Background: KTE-X19 is an autologous anti-CD19 CAR T-cell therapy approved in the US and EU for the treatment of R/R MCL. In the ZUMA-2 study of KTE-X19 in R/R MCL, the objective response rate (ORR) at a median 17.5-mo follow-up was 92% (67% complete responses [CR]; Wang et al. ASH 2020 #1120). Here, we report results in pts with or w/o POD24, an indicator of poor outcomes (Visco et al. Br J Haematol 2019). Methods: Eligible pts with R/R MCL underwent leukapheresis and conditioning chemotherapy followed by a single infusion of KTE-X19. Efficacy results are reported for the 60 treated pts with ≥1 y of follow-up (median 17.5 mo); safety results are presented for all 68 treated pts. Results: High-risk disease characteristics were common in pts with (n=33) and w/o POD24 (n=35), although pts with POD24 had higher tumor burden and lactate dehydrogenase (LDH) levels, and more had blastoid type MCL (Table). ORR in pts with (n=28) and w/o POD24 (n=32) was 93% and 91%, with CR rates of 61% and 72%. In pts with and w/o POD24, median progression-free survival (PFS) was 11.3 mo (range, 0.9–30.3) and 29.3 mo (range, 0–35.9). Medians for duration of response (DOR) and overall survival (OS) were not reached in either group. Most common Grade ≥3 adverse events (AEs) in pts with vs w/o POD24 were neutropenia (91% vs 80%), thrombocytopenia (61% vs 46%), and anemia (55% vs 51%); Grade ≥3 cytokine release syndrome (CRS) and neurologic events occurred in 9% vs 20% and 27% vs 34%, respectively. There were no cases of Grade 5 CRS, KTE-X19–related secondary cancers, or replication-competent retrovirus in either group. In pts with vs w/o POD24, median peak CAR T-cell levels and median area under the curve were 53.4 cells/µL (range, 0.2–2566) and 583.4 cells/µL (range, 1.8–27,743.6) vs 112.4 cells/µL (range, 0.2–2589) and 1588.3 cells/µL (range, 3.8–27,238.7); by 12 mo, B cells were detectable in 8/11 (73%) vs 7/15 pts (47%) in ongoing response. Conclusions: KTE-X19 provided a high CR rate across all pts, with median DOR and OS not reached. Pts with POD24 had more aggressive high-risk disease characteristics (tumor burden, LDH levels, and blastoid MCL) and generally lower CAR T-cell expansion and PFS vs pts w/o POD24. Earlier intervention with CD19-directed CAR T-cell therapy may benefit pts with MCL with known high-risk factors. Clinical trial information: NCT02601313. [Table: see text]

Effect of adding ublituximab to ibrutinib on PFS, ORR, and MRD negativity in previously treated high-risk chronic lymphocytic leukemia: Final results of the GENUINE phase III study

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Background: The BTK inhibitor ibrutinib (IB) has advanced the treatment for patients (pts) with CLL, however, among pts with high-risk CLL, disease control with IB is less durable. Ublituximab (UTX) is a glycoengineered mAb with enhanced ADCC. The GENUINE study evaluated the addition of UTX to IB vs. IB alone in high-risk rel/ref CLL. With a median follow up now 3.5+ yrs, we present the final results. Methods: Eligible pts having rel/ref CLL with centrally confirmed del17p, del11q, and/or a TP53 mutation, were randomized 1:1 to IB (420 mg QD) alone or with UTX (900 mg on D1, 8, 15 of Cy 1, D1 of Cy 2-6, and Q3 Cy thereafter). No limit on # of prior Tx; prior IB excluded. Primary endpoint was overall response rate (ORR) by iwCLL 2008 (excludes PR-L); secondary endpoints were CR rate, peripheral blood MRD negativity (analyzed centrally), PFS, and safety. Response was by blinded independent review. Results: 117 pts were treated (59 in UTX + IB arm; 58 in IB arm). Med age was 66 yrs and med # of prior Tx was 1 (range 1-5) for each arm. Baseline features were relatively balanced including ECOG, gender, and med time since diagnosis (6+ yrs). 17p del was greater in the IB arm (50% vs 44%); bulky disease was greater in UTX + IB arm (47% vs 28%); IGHV-unmut was 83% for both arms. At data-cutoff of Sep 1, 2019, AEs were comparable between the arms, except infusion reactions (UTX + IB: All G 53% / G 3/4 3%) and neutropenia (All G 36% vs 21%, G 3/4 19% vs. 12%) which were higher for UTX + IB. At a med follow up of 42 mos, all efficacy endpoints were in favor of UTX + IB (see Table). Conclusions: In contrast to prior studies adding rituximab to IB, GENUINE is the first randomized trial to demonstrate a PFS benefit with the addition of an anti-CD20 to IB. Increasing depth of response (CR rate, MRD-neg) post first year of Tx supports maintenance therapy with UTX. Clinical trial information: NCT02301156 . [Table: see text]

Trial in progress: a phase II, multicenter, single-arm study of zanubrutinib (BGB-3111) in patients with previously treated chronic lymphocytic leukemia/small lymphocytic lymphoma intolerant of prior treatment with ibrutinib

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Background: Ibrutinib (ibr), a Bruton tyrosine kinase inhibitor (BTKi), was shown to improve patient outcomes in chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL); however, adverse events (AEs) were the most common reason for discontinuing ibr (50% and 63% of discontinuations in relapse/refractory (R/R) and frontline patients, respectively; Haematologica. 2018:103:874). Zanubrutinib, an approved BTKi for mantle cell lymphoma, was specifically engineered to optimize selectivity. Pooled clinical data from 6 zanubrutinib monotherapy trials in B-cell malignancies (N=682 patients; R/R CLL/SLL [n=91]) suggested that zanubrutinib monotherapy was well tolerated and demonstrated a low rate of treatment discontinuation from AEs (9%; Tam, EHA 2019). Presented here is a trial-in-progress that will evaluate whether zanubrutinib monotherapy may serve as a therapeutic option for patients with CLL/SLL who have become ibr intolerant. Methods: The ongoing phase II, multicenter, US, single-arm, open-label study (NCT04116437, BGB-3111-215) will evaluate zanubrutinib monotherapy (160mg twice daily) as a treatment option for patients with CLL/SLL intolerant to prior ibr treatment. Approximately 60 patients will be enrolled from ~30 community medical centers. Key inclusion criteria include CLL/SLL requiring treatment per International Workshop on CLL criteria ( Blood. 2018;131:2745) before ibr therapy, intolerance to ibr (defined as an unacceptable AE for which, per investigator’s opinion, ibr treatment should be discontinued despite optimal supportive therapy), resolution of ibr-related AEs to grade ≤1 or baseline, and an ECOG PS 0-2. Key exclusion criteria include having an intervening cancer therapy between ibr and zanubrutinib, a documented disease progression during ibr treatment up to the time of enrollment, and a history of central nervous system (CNS) hemorrhage. The primary endpoint is frequency and severity of protocol-specified treatment-emergent AEs (diarrhea, myalgia, muscle spasm, arthralgia, hypertension, fatigue, rash, atrial fibrillation, and hemorrhage excluding CNS hemorrhage). The secondary endpoints include overall response rate, progression-free survival, and patient-reported outcomes. An exploratory endpoint was added to evaluate clinical effects (physical activity, treatment-related symptoms, and quality of life) using a smartphone app. Recruitment is ongoing. Clinical trial information: NCT04116437 .

Fostamatinib for the treatment of diffuse large B-cell lymphoma

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Background: Diffuse large B-cell lymphoma (DLBCL) is an aggressive and common form of non-Hodgkin’s lymphoma, characterized by marked genetic heterogeneity. The disease is difficult to treat, and patients with relapsed/refractory DLBCL often have poor outcomes. Some subsets of DLBCL have an increased reliance on B-cell receptor (BCR) activity. Spleen tyrosine kinase (SYK) is a signaling molecule essential for BCR activation. Fostamatinib, an oral SYK inhibitor, was evaluated for treatment of relapsed/refractory DLBCL in a phase 2 randomized, placebo-controlled trial1(NCT01499303), and 9 patients had clinical benefit (1 complete response, 1 partial response, and 7 stable disease). The patients with clinical benefit from fostamatinib treatment had DLBCL of germinal center B-cell (GCB) or intermediate cell of origin. We present the clinical outcomes of 2 patients from this trial who continued to benefit from fostamatinib treatment for over 6 years. Methods: Medical records for the 2 patients were retrospectively reviewed for dose regimen, clinical response, and safety data. Results: Patient A, a 63-year-old male patient with DLBCL of GCB origin, had been diagnosed with follicular lymphoma in 1996, transformation in 2002. He had undergone 1 line of treatment for follicular lymphoma and 5 treatments for DLBCL prior to fostamatinib treatment. He started fostamatinib at 100mg BID in Dec 2012, which was reduced to 100mg daily in Apr 2013, and patient continues at 100 mg QD. Patient A has maintained a complete response (CR) for > 5 years. An isolated infra-centimetric suspicious lesion was noted in Patient A in May 2019, which is stable as of January 2020 with a progressive decrease of metabolic activity. Patient B, a male with DLBCL of an intermediate cell of origin, was 69 years old at baseline with 2 DLBCL treatments prior to fostamatinib treatment since his diagnosis in Aug 2012. He started fostamatinib in May 2013 at 200 mg BID with no dose changes over the last 7 years. Patient B had a partial response (PR) per Chesson criteria since December 2014, with a sustained improved metabolic response continuing since ( > 6 years), with all but a single metastatic site no longer visible. The only serious adverse event in these 2 patients was a ventricular fibrillation and grade 4 cardiac arrest at Day 90 in Patient B, necessitating defibrillation insertion. This was deemed unrelated to treatment and resolved. Conclusions: Fostamatinib may provide durable benefit to a small subset of patients with relapsed/refractory DLBCL. 1. Flinn, I.W., et al., Eur J. Cancer 2016; 54:11-17

Brentuximab vedotin in combination with nivolumab, doxorubicin, and dacarbazine in newly diagnosed patients with advanced-stage Hodgkin lymphoma (Trial in Progress)

TPS8068

Background: Brentuximab vedotin (BV, ADCETRIS) is approved for the treatment of adults with treatment-naïve Stage III or IV cHL in combination with AVD (Connors 2017). Nivolumab is approved for treatment of adults with relapsed/refractory cHL. Both agents have been well tolerated with promising activity when combined with multi-agent chemotherapy. The combination of BV plus nivolumab was evaluated as a frontline treatment option for patients (pts) with cHL who are over 60 years and ineligible for or declined conventional combination chemotherapy (Friedberg, 2018). The ongoing study reported an ORR of 82% in 11 pts and appears well tolerated in this population. In another trial in 93 patients in the first salvage setting, the combination produced a 67% CR rate (Herrera 2018, Moskowitz 2019) and the majority of patients were able to undergo subsequent stem cell transplant. It is reasonable to expect that the combination of BV, nivolumab, A, and D (AN + AD) will result in high response rates and be well tolerated, with potentially less toxicity. Methods: SGN35-027 (NCT03646123) is a phase 2 study designed to evaluate the efficacy and safety of A+AVD when administered with growth factor prophylaxis in pts with stage III/IV cHL (Part A). Part B will evaluate the combination of AN + AD in a similar patient population. The primary objective of Part B is to estimate the CR rate at EOT in pts with treatment-naïve advanced cHL. Patients in Part B will have Ann Arbor Stage IIB/III/IV cHL or Stage IIA cHL with bulky mediastinal disease. Enrollment is ongoing in both parts of the study. Approximately 50 pts will be enrolled in Part B. All pts will be treated with BV 1.2 mg/kg, nivolumab 240 mg, doxorubicin 25 mg/m2, and dacarbazine 375 mg/m2, administered separately by IV infusion on Days 1 and 15 of each 28-day cycle for up to 6 cycles. Efficacy will be assessed by PET/CT scans at C2 and EOT. Disease assessments will be performed periodically during follow up. Disease response and progression will be assessed using Lugano with the incorporation of LYRIC (Cheson 2016). Clinical trial information: NCT03646123 .

Effect of dose modifications on response to duvelisib in patients with relapsed/refractory (R/R) CLL/SLL in the DUO trial

7523

Background: Duvelisib (DUV), a first-in-class oral dual PI3K-δ,γ inhibitor, is approved for treatment (tx) of R/R CLL/SLL after ≥ 2 prior therapies. In the phase 3 DUO trial, DUV 25 mg BID significantly improved efficacy vs ofatumumab (OFA; mPFS, 13.3 vs 9.9 mo; HR, 0.52 [ P < .0001]; ORR, 74% vs 45% [ P < .0001]) in pts with R/R CLL/SLL. Tx-emergent AEs (TEAEs) of special interest (AESIs) such as infections, diarrhea, colitis, neutropenia, rash, ALT/AST elevation, and pneumonitis, were moderate and manageable with early intervention and dose modification. We examined dose-modification patterns and their impact on response to DUV in the DUO trial. Methods: Dose interruptions (DI) or reductions (DR) to 15, 10, or 5 mg BID were permitted per study protocol to manage TEAEs. Responses were assessed by IRC. Results: Among 158 DUV-treated pts, median duration of DUV exposure was 11.6 mo (vs 5.3 mo, OFA). DI and DR occurred in 80% (126/158) and 27% (43/158) of pts, respectively. The most common cause of DI was diarrhea (23%), followed by neutropenia (12%) and pneumonia or colitis (11% each). Among responders (n = 118), median time to first response on DUV was 1.9 mo and estimated median duration of response was 11.1 mo. Median time to first DI was 3.9 mo and median duration of DI was 15 d (range, 1-133 d). Response to DUV was improved or maintained in most pts evaluated for response who had ≥ 1 DI for > 1 wk (84% [42/50]) or > 2 wk (82% [31/38]) followed by ≥ 3 wk on DUV. In a landmark analysis, median PFS was similar in pts with DI and those without DI for > 1 wk (17.8 vs 16.3 mo) or > 2 wk (17.8 vs 16.3 mo) within the first 3 mo. The median time to DR after CR/PR was 5.6 mo (n = 25) and median duration was 3.4 mo. Median time to onset across AESIs after starting DUV ranged from 2.2 to 4.3 mo; median time to resolution was within 4 wk across AESIs. Proportions of pts experiencing AESIs were stable or decreased over time after 3-6 mo: 0-3 mo, 64% (101/158); > 3-6 mo, 63% (86/137); > 6-9 mo, 47% (54/114); > 9-12 mo, 52% (52/100), and seldom led to discontinuation of DUV (≤ 10%). Conclusions: DI/DR can contribute to the effective management of TEAEs with DUV. These findings suggest that DI of > 1-2 weeks or more do not appear to significantly impact response to DUV or PFS. Clinical trial information: NCT02004522.

Efficacy and time to next treatment following lenalidomide/rituximab (R2) or rituximab/placebo in patients with R/R indolent NHL (AUGMENT)

7514

Background: Relapse is expected in treated indolent lymphoma patients, and an unmet need exists to prolong remission with effective therapies. Lenalidomide + rituximab (R2) may improve the efficacy of next treatment by their unique mechanisms. Methods: The AUGMENT phase III study evaluated patients with R/R FL gr 1-3a (82%) and MZL (18%) after ≥ 1 prior systemic therapy (not rituximab refractory). Randomization was 1:1 to R2 (lenalidomide PO 20 mg/d, d1-21/28 X12 cycles [c] + rituximab [R] IV 375 mg/m2/wk, c1, d1, 8, 15, 22 and c2-5, d1) and R/placebo (same dosing schedule). The primary endpoint was PFS by 2007 IWG; secondary/exploratory analyses were time to next antilymphoma/chemotherapy treatment (TTNLT/TTNCT) and response to next treatment. Per regulatory guidance, PFS2 was defined as time from randomization to first PD or death from any cause after next antilymphoma treatment, or initiation of a third antilymphoma treatment. Results: Median PFS was superior for R2 over R/placebo (39.4 vs 14.1 mo; HR = 0.46; P < 0.0001). As of 22June2018, median TTNLT, TTNCT, and PFS2 were not reached for R2, and were significantly longer than R/placebo (HR = 0.54, 0.50, and 0.52, respectively). For 49/178 (28%) R2 and 80/180 (44%) R/placebo patients receiving next antilymphoma therapy, response was generally higher with R2 (57% ORR; 31% CR) than R/placebo (36% ORR; 16% CR; Table). Conclusions: These analyses suggest that R2 (vs R/placebo) prolonged time to subsequent treatment and is associated with longer PFS2, enabling greater response to next therapy. Although patient numbers were modest, it is hypothesized that patients who received R2 were generally more sensitive to subsequent therapy than those treated with R/placebo. Clinical trial information: NCT01938001. [Table: see text]

Managing cytokine release syndrome (CRS) and neurotoxicity with step-fractionated dosing of mosunetuzumab in relapsed/refractory (R/R) B-cell non-Hodgkin lymphoma (NHL)

7518

Background: T-cell directed therapies (e.g., CAR-T, blinatumomab) are associated with significant risk of Grade (Gr) ≥3 neurotoxicity and CRS/infusion-related reaction (IRR). Mosunetuzumab is a CD20/CD3 bispecific antibody that directs T-cells to engage and eliminate malignant B-cells. We report safety results from an ongoing phase 1/1b study of mosunetuzumab in patients (pts) with R/R B-cell NHL. Methods: Pts received ascending doses on Day 1, Day 8, and Day 15 of Cycle 1 (step-fractionation), then a fixed dose on Day 1 of every 21-day cycle thereafter, up to a maximum of 17 cycles. Primary outcome measures included safety and efficacy. Results: As of October 23, 2018, 114 pts who received step-fractionated dosing of mosunetuzumab were evaluable for safety (Table). The majority of adverse events (AE) occurred during Cycle 1 and 2. Neurologic AEs (NAE), defined from Nervous System or Psychiatric System Organ Classes, were mostly low grade, transient (median duration 4 days) and reversible; most common ones were headache (14%) and dizziness (8%). Gr ≥3 NAEs occurred in 4 pts (4%) with only 1 treatment-related event (hepatic encephalopathy). CRS/IRR was reported in 25% of pts, with only 1 Gr 3 event. Most common CRS symptoms were pyrexia (86%), chills (38%), and tachycardia and headache (14% each). There were no Gr 5 events related to CRS or NAEs. No apparent dose toxicity relationship was observed with step-fractionation in these pts, despite escalation of the Cycle 1 Day 15 dose to 20 mg, consistent with observed peak IL-6 levels after a low Cycle 1 Day 1 dose. In these pts, objective responses were observed in 24/73 (33%; complete response [CR], 13 [18%]) aggressive NHL and 17/32 (53%; CR, 10 [31%]) indolent NHL pts. Conclusions: Step-fractionation has enabled continued dose escalation of mosunetuzumab with no apparent increases in toxicity, exhibiting a promising risk-benefit profile. Clinical trial information: NCT02500407; GO29781. [Table: see text]

ZUMA-8: A phase 1/2 multicenter study evaluating KTE-X19 in patients (pts) with relapsed/refractory (R/R) chronic lymphocytic leukemia (CLL)

TPS7566

Background: Despite treatment advances, CLL is largely incurable. First-line targeted therapy with ibrutinib mostly produces durable remissions, but high-risk disease or many prior therapies increases relapse risk (Ghia P, et al. Haematologica. 2014). Relapse after ibrutinib is associated with a poor outcome (Maddocks KJ, et al. JAMA Oncol. 2015). Allogeneic stem cell transplantation potentially offers long-term remissions but has a high risk of morbidity/mortality (Shustik C, et al. Ann Hematol. 2017). Autologous T cells expressing a CD19-specific chimeric antigen receptor (CAR) with a CD28 costimulatory domain may be efficacious against CLL (Kochenderfer JN, et al. Blood. 2012). KTE-X19 is an autologous anti-CD19 CAR T cell therapy under investigation for R/R hematologic malignancies and may offer longer durable remissions with manageable safety in pts with R/R CLL. ZUMA-8 is a Phase 1/2 multicenter study for pts with R/R CLL. Methods: Adult pts must have R/R CLL with ≥ 2 prior treatment regimens, disease progression on ibrutinib, ECOG 0-1, and adequate organ function. Phase 1 will enroll 12-18 pts to assess dose-limiting toxicities (DLTs) with a 6 + 3 dose escalation/de-escalation design; 30 more pts may be enrolled to further assess safety. Phase 2 will enroll ≈60 pts to evaluate efficacy and safety. Pts will undergo leukapheresis followed by optional bridging therapy. Cyclophosphamide (500 mg/m2) and fludarabine (30 mg/m2) conditioning chemotherapy will be given on Days -5, -4 and -3. KTE-X19 will be given on Day 0 at 0.5, 1 or 2 × 106 KTE-X19 cells/kg. The primary endpoint is incidence of DLTs for Phase 1 and independent review committee-assessed objective response rate (ORR) per iwCLL 2018 criteria for Phase 2. Secondary endpoints include complete remission (CR) rate, investigator-assessed ORR, minimal residual disease (MRD) negativity rate, MRD-negative CR rate, duration of response, progression-free survival, overall survival, safety, and patient-reported outcomes (Phase 2). Serum cytokine and blood KTE-X19 cell levels over time and level of anti-KTE-X19 antibodies are exploratory endpoints. Accrual is ongoing. Clinical trial information: NCT03624036.

Abstract A003: Safety and preliminary efficacy of ACTR707, autologous T lymphocytes expressing an antibody-coupled T-cell receptor, in combination with rituximab in subjects with relapsed or refractory CD20-positive B-cell lymphoma

Background: Autologous T cells engineered to express a universal ACTR chimeric receptor kill tumors through interactions with tumor-targeting antibodies [Kudo, Cancer Res 2014]. ACTR707 was identified through rigorous preclinical screening of more than 100 different ACTR variants. It is composed of the extracellular domain of CD16, the cytoplasmic signaling domain of CD3ζ, and the costimulatory domain of CD28. Study ATTCK-20-03 (NCT03189836) is the first clinical trial of ACTR707. ACTR707 in combination with rituximab is being studied in subjects with relapsed or refractory CD20+ B-cell lymphoma previously treated with anti-CD20 monoclonal antibody (mAb) therapy. Herein we report data from the first dose level of ACTR707, where 6 subjects have been enrolled and treated.Methods: ATTCK-20-03 is a first-in-human, multicenter phase 1 dose escalation study of ACTR707 in combination with rituximab. The primary objective is to evaluate the safety of ACTR707 in combination with rituximab, and secondary objectives include evaluation of antitumor activity, assessment of T-cell expansion and persistence, cytokine levels, and rituximab pharmacokinetics. Eligible subjects must have histologically confirmed relapsed or refractory aggressive CD20+ B-cell lymphoma of DLBCL, MCL, PMBCL, Gr3b FL, or transformed FL subtype and have received prior anti-CD20 mAb therapy in combination with chemotherapy. Subjects received lymphodepleting chemotherapy (cyclophosphamide 400 mg/m2 and fludarabine 30 mg/m2) for 3 days, followed by rituximab (375 mg/m2) and a single infusion of ACTR707. Additional doses of rituximab are administered, one dose every 3 weeks in the absence of disease progression. The study is separated into two sequential phases, a dose escalation and a safety expansion phase. During dose escalation, ACTR707 will be tested at increasing doses in combination with rituximab. Results: Six subjects received ACTR707 in combination with rituximab at the first dose level: 5 diagnosed with DLBCL (83%) and 1 with Gr3b FL (17%). Median age was 61 years (range: 57-76), 83% were male, 50% were treated with ≥ 3 lines of prior therapy, and 67% had no response to or progression within 6 months of immediate prior therapy. ACTR707 was successfully manufactured for all subjects. ACTR+ T cells demonstrated expansion and were detectable at D28 post-ACTR707 infusion for all subjects tested. There were no dose-limiting toxicities observed in the 4 subjects evaluable for DLTs (2 subjects were not DLT-evaluable due to early disease progression). There were no serious adverse events of cytokine release syndrome, neurotoxicity, or autoimmune events and no deaths on study. Grade 3 or higher AEs included neutropenia (n=2), febrile neutropenia (n=2), and thrombocytopenia (n=1). Antitumor activity was assessed in all 6 subjects. Three subjects experienced disease progression and 3 subjects demonstrated investigator-reported complete responses at the first disease response assessment (D42). Responses are ongoing at the time of the data cut-off. Conclusions: In the first dose level studied in subjects with relapsed or refractory aggressive CD20+ B-cell lymphoma, ACTR707 in combination with rituximab induced complete responses in 3 out of 6 treated subjects, with no serious events of cytokine release syndrome or neurotoxicity. ACTR+ T-cells were detectable in all subjects and ACTR+ T-cells persisted in the presence of continued rituximab administration. These results support the continued dose escalation of ACTR707 in combination with rituximab.

Citation Format: Veronika Bachanova, Jonathon Cohen, Luke Akard, Samantha Jaglowski, Jessica Sachs, Ann Ranger, Patricia Harris, Kathleen McGinness, Greg Motz, Ian Flinn. Safety and preliminary efficacy of ACTR707, autologous T lymphocytes expressing an antibody-coupled T-cell receptor, in combination with rituximab in subjects with relapsed or refractory CD20-positive B-cell lymphoma [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr A003.

CD47 Blockade by Hu5F9-G4 and Rituximab in Non-Hodgkin's Lymphoma

BACKGROUND

The Hu5F9-G4 (hereafter, 5F9) antibody is a macrophage immune checkpoint inhibitor blocking CD47 that induces tumor-cell phagocytosis. 5F9 synergizes with rituximab to eliminate B-cell non-Hodgkin's lymphoma cells by enhancing macrophage-mediated antibody-dependent cellular phagocytosis. This combination was evaluated clinically.

METHODS

We conducted a phase 1b study involving patients with relapsed or refractory non-Hodgkin's lymphoma. Patients may have had diffuse large B-cell lymphoma (DLBCL) or follicular lymphoma. 5F9 (at a priming dose of 1 mg per kilogram of body weight, administered intravenously, with weekly maintenance doses of 10 to 30 mg per kilogram) was given with rituximab to determine safety and efficacy and to suggest a phase 2 dose.

RESULTS

A total of 22 patients (15 with DLBCL and 7 with follicular lymphoma) were enrolled. Patients had received a median of 4 (range, 2 to 10) previous therapies, and 95% of the patients had disease that was refractory to rituximab. Adverse events were predominantly of grade 1 or 2. The most common adverse events were anemia and infusion-related reactions. Anemia (an expected on-target effect) was mitigated by the strategy of 5F9 prime and maintenance dosing. Dose-limiting side effects were rare. A selected phase 2 dose of 30 mg of 5F9 per kilogram led to an approximate 100% CD47-receptor occupancy on circulating white and red cells. A total of 50% of the patients had an objective (i.e., complete or partial) response, with 36% having a complete response. The rates of objective response and complete response were 40% and 33%, respectively, among patients with DLBCL and 71% and 43%, respectively, among those with follicular lymphoma. At a median follow-up of 6.2 months among patients with DLBCL and 8.1 months among those with follicular lymphoma, 91% of the responses were ongoing.

CONCLUSIONS

The macrophage checkpoint inhibitor 5F9 combined with rituximab showed promising activity in patients with aggressive and indolent lymphoma. No clinically significant safety events were observed in this initial study. (Funded by Forty Seven and the Leukemia and Lymphoma Society; ClinicalTrials.gov number, NCT02953509 .).

Duvelisib, an oral dual PI3K-δ,γ inhibitor, shows clinical and pharmacodynamic activity in chronic lymphocytic leukemia and small lymphocytic lymphoma in a phase 1 study

Duvelisib (IPI-145), an oral, dual inhibitor of phosphoinositide-3-kinase (PI3K)-δ and -γ, was evaluated in a Phase 1 study in advanced hematologic malignancies, which included expansion cohorts in relapsed/refractory (RR) chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) and treatment-naïve (TN) CLL. Per protocol, TN patients were at least 65 years old or had a del(17p)/TP53 mutation. Duvelisib was administered twice daily (BID) in 28-day cycles at doses of 8-75 mg in RR patients (n = 55) and 25 mg in TN patients (n = 18.) Diarrhea was the most common nonhematologic AE (TN 78%, RR 47%); transaminase elevations the most frequent lab-abnormality AE (TN 33.3%, RR 30.9%); and neutropenia the most common ≥grade 3 AE (RR 44%, TN 33%). The overall response rates were 56.4% for RR patients (1.8% CR, 54.5% PR) and 83.3% for TN patients (all PRs); median response duration was 21.0 months in RR patients but was not reached for TN patients. Based upon phase 1 efficacy, pharmacodynamics, and safety, duvelisib 25 mg BID was selected for further investigation in a phase 3 study in RR CLL/SLL.

Abstract LB-018: ARQ 531, a novel and reversible inhibitor of Bruton's tyrosine kinase, displays favorable oral bioavailability and exposure in patients with B-cell malignancies

Background: ARQ 531 is a novel, ATP competitive reversible inhibitor Bruton's tyrosine kinase (BTK). BTK is a key regulator of the B cell receptor (BCR) signaling pathway that mediates signaling from the cell surface to the cytoplasm and into the nucleus. ARQ 531 is not metabolized by any of the major drug metabolizing CYP450 enzymes. Here we report pharmacokinetic profile of ARQ 531 in a phase I study evaluating safety, pharmacokinetics and pharmacodynamics activity and clinical activity of ARQ 531 in selected subjects with relapsed/refractory B-cell malignancies. Preclinical studies in rats, dogs and monkeys are also described.

Methods: Oral and intravenous single dose pharmacokinetic studies of ARQ 531 were conducted in rats, dogs, and monkeys to determine oral bioavailability and drug exposure. In a standard ‘3+3' dose-escalation study design, ARQ 531 was given orally once per day beginning at 5 mg/dose and escalating for 4 weeks [NCT03162536]. Plasma samples were collected to determine ARQ 531 concentrations and whole blood / PBMCx to quantify pBTK inhibition. Plasma samples from each species were analyzed by liquid chromatography-mass spectrometry/ mass spectrometry (LC-MS/MS).

Results: Consistent with preclinical studies, patients enrolled in the phase I study showed favorable exposures, the steady state peak to trough ratio was generally 3:1 or lower. ARQ 531 had an elimination half-life at steady state of ~24 hr and Cmax occurred 2 to 3 hours after dosing. Pharmacodynamic changes included suppression of BTK phosphorylation. No drug related AEs or DLTs have been observed thus far in the study.

Conclusions: ARQ 531 demonstrates a favorable PK profile in humans supporting once daily dosing. Sufficient plasma levels are attained and high levels of pBTK inhibition in peripheral blood can be achieved following oral dosing. Additional dose and schedule evaluations continue, and updated clinical and biomarker results will be presented.

Citation Format: Terence Hall, Yi Yu, Sudharshan Eathiraj, Deborah Stephens, Ian Flinn, Jennifer Woyach, Brian Schwartz, Ronald E. Savage. ARQ 531, a novel and reversible inhibitor of Bruton's tyrosine kinase, displays favorable oral bioavailability and exposure in patients with B-cell malignancies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-018.

CUDC-907 in relapsed/refractory diffuse large B-cell lymphoma, including patients with MYC-alterations: results from an expanded phase I trial

CUDC-907 is a first-in-class, oral small molecule inhibitor of both HDAC (class I and II) and PI3K (class Iα, β, and δ) enzymes, with demonstrated anti-tumor activity in multiple pre-clinical models, including MYC-driven ones. In this report, we present the safety and preliminary activity results of CUDC-907, with and without rituximab, in patients with relapsed/refractory diffuse large B-cell lymphoma (DLBCL), with a particular focus on those with MYC-altered disease. Thirty-seven DLBCL patients were enrolled, 14 with confirmed MYC-altered disease. Twenty-five patients received monotherapy treatment, and 12 received the combination of CUDC-907 with rituximab. CUDC-907 monotherapy and combination demonstrated similar safety profiles consisting primarily of Grade 1/2 hematologic and gastrointestinal events. The most frequently reported Grade ≥3 treatment-related events were thrombocytopenia, neutropenia, diarrhea, fatigue, and anemia. Eleven responses (5 complete responses and 6 partial responses) were reported, for a response rate of 37% (11 out of 30) in evaluable patients [30% (11 out of 37) including all patients]. The objective response rate in evaluable MYC-altered DLBCL patients was 64% (7 out of 11; 4 complete responses and 3 partial responses), while it was 29% (2 out of 7) in MYC unaltered, and 17% (2 out of 12) in those with unknown MYC status. Median duration of response was 11.2 months overall; 13.6 months in MYC-altered patients, 6.0 months in MYC unaltered, and 7.8 months in those with MYC status unknown. The tolerable safety profile and encouraging evidence of durable anti-tumor activity, particularly in MYC-altered patients, support the continued development of CUDC-907 in these populations of high unmet need. (clinicaltrials.gov identifier: 01742988).

Obinutuzumab or Rituximab Plus Cyclophosphamide, Doxorubicin, Vincristine, and Prednisone in Previously Untreated Diffuse Large B-Cell Lymphoma

Purpose Rituximab (R) plus CHOP (cyclophosphamide, doxorubicin, vincristine, prednisone) chemotherapy is the standard of care in previously untreated diffuse large B-cell lymphoma (DLBCL). Obinutuzumab (G) is a glycoengineered, type II, anti-CD20 monoclonal antibody. GOYA was a randomized phase III study that compared G-CHOP with R-CHOP in patients with previously untreated advanced-stage DLBCL. Methods Patients (N = 1,418) were randomly assigned to receive eight 21-day cycles of G (n = 706) or R (n = 712), plus six or eight cycles of CHOP. Primary end point was investigator-assessed progression-free survival (PFS). Results After median observation of 29 months, the number of investigator-assessed PFS events was similar between G (201; 28.5%) and R (215; 30.2%), stratified hazard ratio was 0.92 (95% CI, 0.76 to 1.11; P = .39), and 3-year PFS rates were 70% and 67%, respectively. Secondary end points of independently reviewed PFS, other time-to-event end points, and tumor response rates were similar between arms. In exploratory subgroup analyses, patients with germinal-center B cell-like subtype had a better PFS than did patients with activated B cell-like subtype, irrespective of treatment. Frequencies of grade 3 to 5 adverse events (AEs; 73.7% v 64.7%, respectively) and serious AEs (42.6% v 37.6%, respectively) were higher with G-CHOP compared with R-CHOP. Fatal AE frequencies were 5.8% for G-CHOP and 4.3% for R-CHOP. The most common AEs were neutropenia (G-CHOP, 48.3%; R-CHOP, 40.7%), infusion-related reactions (G-CHOP, 36.1%; R-CHOP, 23.5%), nausea (G-CHOP, 29.4%; R-CHOP, 28.3%), and constipation (G-CHOP, 23.4%; R-CHOP, 24.5%). Conclusion G-CHOP did not improve PFS compared with R-CHOP in patients with previously untreated DLBCL. AEs reported with G were consistent with the known safety profile. Biomarker analyses may help define a future role for G in DLBCL.