Targeting CD20 Research Articles

Preliminary Results of Nathali-01: A First-in-Human Phase I/IIa Study of UCART20x22, a Dual Allogeneic CAR-T Cell Product Targeting CD20 and CD22, in Relapsed or Refractory (R/R) Non-Hodgkin Lymphoma (NHL)

Background: UCART20x22 is a dual targeted allogeneic CAR T-cell product candidate generated from healthy donor T-cells. Donor-derived T-cells are transduced with a bicistronic lentiviral vector to express CARs targeting CD20 and CD22. TALEN ® gene editing technology is used to inactivate the TRAC and CD52 genes to minimize graft-versus-host disease (GvHD) and allow for the use of alemtuzumab (CLLS52, an anti-CD52 monoclonal antibody) in the lymphodepletion (LD) regimen, respectively. UCART20x22 previously demonstrated robust and sustained activity in vitro and in vivo (Aranda-Orgilles B, et al. Cancer Immunol Res 2023). Here we present the initial preliminary results from the NatHaLi-01 trial (NCT05607420), the first-in-human Phase 1/2a dose-finding and expansion study evaluating UCART20x22 in R/R B-cell NHL. Methods: The primary endpoints are safety, tolerability, and determining the recommended phase 2 dose of UCART20x22. Additional endpoints include anti-lymphoma activity and cellular kinetics of UCART20x22. Key eligibility criteria are age 18-80y, lymphoma expression of CD20 and/or CD22 by local assessment, and ≥ 2 prior treatment regimens including autologous CD19 CAR T-cell therapy (CAR19), if eligible. After LD with FCA (fludarabine 30 mg/m 2 × 3d, cyclophosphamide 0.5g/m 2 × 3d, CLLS52 12 mg on D1, 24 mg on D2, D3), a single infusion of UCART20x22 is administered at a flat dose level ([DL1] 50 x 10 6 cells; [DL2] 150 x 10 6 cells; and [DL3] 450 x 10 6 cells). Results: As of 01 July 2023, 3 pts were enrolled and treated at DL1. Pt 1 is a 76yo female with double-expressor diffuse large B-cell lymphoma (DLBCL) relapsed after R-CHOP, radiation therapy, and polatuzumab vedotin with bendamustine/rituximab (BR) and was considered ineligible for CAR19 due to recent high dose bendamustine. Pt 2 is a 65yo female with R/R triple-hit lymphoma transformed from follicular lymphoma who was previously treated with radiation therapy, BR, dose-adjusted R-EPOCH, and two separate CAR19 treatments. Pt 3 is an 18yo female with R/R DLBCL transformed from marginal zone lymphoma who previously received chemoimmunotherapy, venetoclax, ibrutinib, BR, CAR19, obinutuzumab, glofitamab, tafasitamab, lenalidomide, and an experimental epigenetic modifier. Cytokine release syndrome (CRS) occurred in all patients. Pt 1 had G1 CRS and received tocilizumab (toci) x3 and dexamethasone (dex) x1. Pt 2 had G2 CRS and received toci and dex x1. Pt 3 had G1 CRS and received toci x1. All pts' CRS resolved with treatment. No immune effector cell associated neurotoxicity (ICANS) or GvHD was observed. There were no UCART20x22 dose limiting toxicities (DLTs), and there was 1 CLLS52 SAE and 1 DLT. The SAE was G3 CMV reactivation and was managed with IV antivirals. The DLT was in Pt 2, who entered the study with G1/2 cytopenias and a hypocellular bone marrow and had prolonged bone marrow aplasia after treatment thought to be due to cumulative chemotherapy exposure. This pt proceeded to allogeneic hematopoietic stem cell transplant (HSCT) from a matched donor while in complete remission from UCART20x22 treatment. Responses were assessed per Lugano criteria beginning on D28. At D28, all 3 pts responded with 2 CRs and 1 PR. Host lymphocytes remained suppressed through D28 for all pts. UCART20x22 expansion was observed by flow cytometry in 3/3 pts and was initially detected on D7 followed by peaks between D9-14. Peak expansion ranged from 16-682 cells/μL and was predominantly CD8 T-cells. Ferritin levels and increases in serum cytokines, including IFNγ, TNFα, IL-2, and IL-6, correlated closely with UCART20x22 expansion. Summary: Treatment with UCART20x22 at DL1 has been safe and well-tolerated, with no UCART20x22 DLTs or ICANS, and CRS was <G3 in all pts. There was 1 DLT of prolonged bone marrow aplasia in a pt with impaired hematopoietic reserve at study entry. UCART20x22 was active at DL1, with all 3 pts responding, including 2 CRs in pts who had previously received CAR19. UCART20x22 expansion was observed in all pts. These initial data support the continued study of UCART20x22 in R/R NHL, and updated results will be presented.

Phase 1/2 Study of Donor-Derived Anti-CD33 Chimeric Antigen Receptor Expressing T Cells (VCAR33) in Patients with Relapsed or Refractory Acute Myeloid Leukemia after Allogeneic Hematopoietic Cell Transplantation

Background and Significance: Although allogeneic hematopoietic cell transplantation (alloHCT) is a potentially curative therapy for patients with high-risk acute myeloid leukemia (AML), relapse occurs in 30% to 40% of alloHCT recipients and is associated with a 2-year post-relapse survival rate of less than 20%. Chimeric antigen receptor (CAR) T cells targeting tumor-associated antigens have demonstrated efficacy in relapsed/refractory (R/R) acute lymphoblastic leukemia and other hematologic malignancies, but there is limited clinical experience with CAR T cell therapies for AML. Current challenges for autologous AML CAR T cell therapy include the inability to harvest adequate numbers of functional, undifferentiated T cells as CAR T cell starting material. In addition, the potential presence of AML blasts in an autologous cell collection can interfere with T cell proliferation and function during the manufacturing process. To circumvent these impediments in patients with R/R AML after alloHCT, VCAR33 represents a CD33-directed CAR T cell product generated from lymphocytes from each patient's prior allogeneic stem cell donor. CAR T cell manufacture from HLA-matched donors will likely not only eliminate delays and failures in production due to lymphopenia but also improve T cell function by using healthy starting material. CD33 is a preferential target for AML CAR T cell therapy as it is expressed on the majority (>80%) of AML blasts and because prior clinical experience with gemtuzumab ozogamicin (GO; tradename: Mylotarg TM) has demonstrated the safety and efficacy of targeting CD33. Study Design and Methods: Study NCTxxxxxxxx* is a multi-center phase 1/2 study evaluating the safety and preliminary efficacy of VCAR33, donor-derived allogeneic CAR T cells targeting CD33 (Figure 1). The CAR construct used for the manufacture of VCAR33 contains a lintuzumab-derived binding domain and a CD28 co-stimulatory domain. Key inclusion criteria include adult patients with relapsed or measurable residual disease positive (MRD+) AML after undergoing alloHCT with an 8/8 HLA-matched related or unrelated donor. Patients who have undergone alloHCT with trem-cel, a CD33-deleted allogeneic stem cell product intended to facilitate the post-HCT treatment with CD33-directed therapies by reducing on-target off-tumor hematotoxicity, may also participate. Patients will be assigned to one of two study arms based on their AML disease burden: Arm A for morphologic disease with ≥ 5% blasts in the bone marrow, or Arm B for MRD+ defined as < 5% blasts in the bone marrow with ≥ 0.1% CD33+ leukemia cells by flow cytometry. The patient's prior stem cell donor undergoes apheresis for collection of mononuclear cells, which are used as starting material for VCAR33 manufacturing. Patients will receive lymphodepletion on days -5 to -2 with fludarabine (total 120 mg/m 2) and cyclophosphamide (total 1000 mg/m 2) followed by infusion of VCAR33 on Day 0. Each study arm will enroll and escalate independently according to a standard 3+3 trial design, starting at 1 x 10 6 CAR T cells/kg for Dose Level 1. The dose limiting toxicity monitoring period is 28 days, at which time patients will undergo evaluation of disease response. Secondary endpoints include incidence of cytokine release syndrome, graft-vs-host disease, and clinical response. Exploratory endpoints aim to correlate VCAR33 properties with clinical response by characterizing T cell phenotypes within the VCAR33 product and by examining VCAR33 expansion and persistence after infusion. Follow up on trial will continue for up to 2 years after infusion followed by long term monitoring for up to 15 years. Patients may undergo second alloHCT for consolidation of remission or for rescue of prolonged cytopenia due to on-target off-tumor effects of VCAR33. *NCT number pending. Clinical trial information submitted to CT.gov on July 19, 2023.

Brentuximab Vedotin in Frontline Therapy of Hodgkin Lymphoma in Patients with Significant Comorbidities Ineligible for Standard Chemotherapy (SGN35-015 Part E)

Brentuximab vedotin (BV) is approved for the treatment of adults with treatment-naïve stage III or IV classical Hodgkin lymphoma (cHL) combined with doxorubicin, vinblastine, and dacarbazine (AVD) and targets CD30, a receptor expressed on the Reed Sternberg cells. Treatment with BV plus AVD has demonstrated improved overall survival (OS) (6-year OS estimate of 93.9% vs 89.4%; HR, 0.59; 95% CI, 0.40-0.88; P=0.009) compared with the standard chemotherapy combination of doxorubicin, bleomycin, vinblastine, and dacarbazine (Ansell 2022). For patients (pts) newly diagnosed with cHL, current treatment options have improved pt outcomes in recent years, but survival rates are still very low for those with significant comorbidities. Pts with comorbid conditions can have poor outcomes due to decreased ability to tolerate dose intensity, increased treatment-related toxicity, and cHL relapse. This study is evaluating the efficacy and safety of single-agent BV as frontline therapy in cHL pts who are ineligible for conventional combination chemotherapy because of comorbidities. SGN35-015 Part E (NCT01716806) was a phase 2, open-label study of BV as frontline cHL therapy. Eligible pts (≥18 years) were unfit for initial conventional combination chemotherapy for cHL as documented by a modified Cumulative Illness Rating Scale score ≥10 or because they required or depended on others for instrumental activities of daily living. Pts received BV (1.8 mg/kg) on Day 1 of each 3-week cycle for up to 16 cycles. Granulocyte colony-stimulating factor prophylaxis was not required. The primary endpoint, objective response rate (ORR), was assessed by Blinded Independent Central Review (BICR) according to the Modified Lugano Criteria (Cheson 2014). Key secondary endpoints included safety, duration of response (DOR), complete response (CR) rate using the Lugano Criteria (Cheson 2014), duration of CR, progression-free survival (PFS), and OS. Thirty pts with cHL received BV and the median age was 76 years (range, 54 to 93 years). Most pts were female (53%) and had a disease stage of II (37%) or III (37%), an Eastern Cooperative Oncology Group (ECOG) performance status of ≥2 (50%; 10 pts [33%] and 5 pts [17%] had an ECOG performance status of 2 and 3, respectively). The median treatment duration was 18 weeks (range, 1 to 50 weeks). Per BICR, the ORR was 60% (18/30) (95% CI: 40.6%, 77.3%), including 33% (10/30) with a CR and 27% (8/30) with a partial response. Six pts (20%) did not respond to treatment: 1 (3%) with progressive disease and 5 (17%) with stable disease; one pt (3%) was not evaluable and the remaining 5 pts (17%) did not have postbaseline responses, either because of death before first scheduled response assessment or not yet reaching the first scheduled response assessment. Median DOR was 7.4 months (95% CI: 7.4 months, not estimable) and median PFS was 8.7 months (95% CI: 5.1 months, not estimable). Median duration of CR was not estimable (95% CI: 7.4 months, not estimable). With a median follow-up of 14.6 months (range, 0 to 44 months), the 2-year OS rate was 70% (95% CI: 48%, 84%). A total of 18 pts (60%) experienced grade ≥3 treatment-emergent adverse events (TEAEs). The most common grade ≥3 TEAEs were fatigue (n=3; 10%), acute kidney injury, anemia, atrial fibrillation, back pain, gait disturbance, hypoxia, neutrophil count decreased, pneumonia, sepsis, syncope, and vomiting (n=2 each; 7%). Nine pts (30%) discontinued treatment because of a TEAE; 1 death due to a TEAE (failure to thrive) was considered treatment-related. Thirteen percent (n=4) of pts experienced grade ≥3 peripheral neuropathy. In pts with cHL who are unfit for initial conventional chemotherapy due to comorbidities, BV monotherapy as frontline treatment appears effective, has an acceptable safety profile, and despite the small sample size could be considered as an option for pts with cHL who are unfit for conventional chemotherapy.

Integrated Preclinical Data Analysis of ISB 2001 Enables Optimal Starting Dose Selection for a First-in-Class Trispecific T Cell Engager Phase1 Study in Multiple Myeloma

Despite significant clinical benefit achieved by targeted immunotherapies in recent years, durable responses are still limited in multiple myeloma (MM) 1,2 potentially due to expansion of clones with low target expression 3,4,5. We have previously reported ISB 2001 as a first in class trispecific T cell engager (TCE) targeting BCMA and CD38 with a superior potency to a single Tumor Associated Antigen TCE 6,7. TCEs are often not fully cross reactive with preclinical species for conducting GLP toxicology. For TCEs, a MABEL approach is often used to derive a starting dose 9, generally requiring multiple dose escalations with low probability of patient benefit before an efficacious dose is reached. As ISB 2001 lacks cynomolgus cross reactivity, we could have used a MABEL approach to derive the starting dose. Instead, we generated datasets employing in vitro and in vivo models for ISB 2001 and teclistamab (possessing a similar mode of action). A quantitative systems pharmacology (QSP) model 8 incorporating in vitro and in vivo data was developed and used to predict clinically efficacious doses for both molecules. The QSP model demonstrated that inclusion of in vivo data was key to the best prediction of actual clinical efficacy for teclistamab. Based on this benchmarking, the ISB 2001 efficacious dose range and minimal pharmacologically active dose (MPAD) were derived. Further refinement of the starting dose was performed by introducing step-up dose administration to mitigate the risk of cytokine release syndrome and to reduce the concentration of the first administration of ISB 2001 below the threshold of cytokine release in vitro. This strategy led to the first full dose, which was approximately two-fold lower than the MPAD but 60-fold greater than the MABEL-based starting dose, and therefore significantly reduced patient exposure to sub-therapeutic doses. This approach for the selection of the starting dose for the First-in-Human clinical study was accepted by the U.S. FDA and the Human Research Ethics Committee in Australia. The utility of QSP modelling in the development of trispecific TCEs has been demonstrated before 10,11. However, to our knowledge this is the first time that a starting dose in clinical studies of a trispecific TCE, lacking species cross-reactivity and therefore a GLP toxicology preclinical package, has been derived based on integrated preclinical data analysis utilizing a QSP model. Clinical evaluation of ISB 2001 is ongoing in a phase I dose escalation and dose expansion study in subjects with relapsed/refractory MM (NCT05862012).

Development of a Phase 1 Study Evaluating the Activity of Modular CAR T for Multiple Myeloma (MCARTY) Targeting BCMA and CD19 for Improved Persistence

CONCLUSION BCMA directed CAR T cell therapy for multiple myeloma (MM) shows promise, but very long-term survival may be limited. Notably, BCMA CAR T persistence in MM is shorter than that seen in with CD19 CAR T cells in B cell malignancies where long-term CD19 CAR T persistence is associated with durable responses. Shorter BCMA CAR T persistence may be explained by the lower surface density of BCMA on tumour compared with that of CD19. Alternatively, CD19 CAR T persistence may be driven by recognition of continuous emergence of newly differentiated B cells. We sought to improve BCMA CAR T persistence by (a) developing a BCMA CAR with high sensitivity to BCMA, and (b) co-expression with a CD19 CAR. Notably, while CD19 is absent or expressed at low level on myeloma cells, CD19 may be expressed on a subpopulation of myeloma stem cells, providing an additional rationale for co-targeting CD19 in MM. We performed functional screening of several mid to high affinity BCMA binders in CAR format. We additionally explored whether a more stable CAR format would improve sensitivity. We explored co-expression of the new BCMA CAR with the CD19 CAR from obecabatagene autoleucel (also known as CAT19), which is known to drive long-term persistence. We also designed and started a clinical study (MCARTY, NCT04795882) testing the BCMA CAR alone or co-expressed with a CD19 CAR in patients with refractory Myeloma. The binding affinity for BCMA was determined for 13 antibody clones from a rat library, before being assessed functionally in single chain variable fragment (scFv) and fragment antigen-binding (Fab) formats in a second generation (41bbζ) CAR backbone. Noting superior target binding, functional efficacy and minimal basal activation of effector cells expressing the D8 binder in Fab format we then assessed this construct against standard BCMA targeting CARs based on the bb2121 and LCAR-B38M binders used in Ide-Cel and Cilta-Cel respectively. Compared to these competitor CARs, D8 demonstrated improved sensitivity to BCMA with improved activation, target kill, and cytokine release in a series of cocultures with plate bound antigen and cell targets expressing low level BCMA. Successful manufacture in an academic setting of dual targeting CAR T cells was achieved by double transduction of autologous CD4/CD8 selected T cells with separate lentiviral vectors titrated for equal transduction. Manufacture by CliniMACS Prodigy included AKT inhibitor VIII to reduce T cell differentiation and LentiBoost, a polaxamer-based transduction enhancer, in a protocol lasting 6-8 days. This resulted in 3 populations of CAR T cells (D8+CAT19-, D8-CAT19+, D8+CAT19+) which can be individually tracked in treated patients. The MCARTY trial is a single centre, Phase 1 dose escalation trial uniquely designed with two cohorts to evaluate the safety of D8 CAR T cells (Cohort 1) and D8/CAT19 CAR T cells (Cohort 2) in patients with relapsed/refractory MM at a dose of 50 or 150x10^6 CARs. Inclusion criteria are: progression or stable disease to last treatment, 3 or more previous lines of therapy, exposure to proteasome inhibitors (PI), immunomodulatory drugs (IMID) and CD38 antibodies, ECOG 0/1. There was no selection based on previous exposure to BCMA targeting agents or tumour BCMA expression. As of 11 July, 8 patients have been treated, 6 patients with D8 CAR alone (n=3 at each dose level) and 2 patients with the lower dose of dual targeting D8/CAT19 CAR T cells. Median age was 57 (range 33-66), high risk cytogenetics in 4 of 7 patients (57%), previous lines of therapy 4 (range 3-8). Doses were well tolerated with no cases of ICANS or CRS≥ grade 3. At a median follow up of 4.5 months (range 1-12), clinical responses ≥PR were seen in all patients (ORR: 100%). Of 6 patients, 5 (83%) CR/sCR, 1 (17%) PR at 3 months. We observed robust expansion of D8 CAR in Cohort 1, and of dual and single targeting CARs in Cohort 2. We report a unique approach to prolong CAR persistence in MM by developing a CAR T cell co-expressing a sensitive BCMA CAR construct and CD19 CAR with proven durability. We report feasibility of double transduction, the first clinical use of a FabCAR and a unique trial design allowing comparison of treatment with single vs dual targeting CAR constructs.

Updated Results of a Phase I Open-Label Single-Arm Study of Dual Targeting BCMA and CD19 Fastcar-T Cells (GC012F) As First-Line Therapy for Transplant-Eligible Newly Diagnosed High-Risk Multiple Myeloma

Background High-risk (HR) newly-diagnosed multiple myeloma (NDMM) has poor outcomes with standard first-line therapies, even in transplant-eligible (TE) patients (pts). A CAR-T therapy with high efficacy and manageable safety profile would be a potential solution to this significant unmet need. GC012F is an autologous B cell maturation antigen (BCMA) and CD19 dual-targeting CAR-T cells therapy developed on the novel FasTCAR-T enabling next-day manufacturing platform [J Clin Oncol 41, 2023 (suppl; abstr 8005)]. The phase I single-arm study has been conducted in frontline setting for TE high-risk NDMM pts to characterize the safety and feasibility of GC012F CAR-T cell therapy (NCT04935580). The data was presented at ASH 2022 for initial 13 pts (Blood (2022) 140 (Supplement 1): 889-890.). Here we present updated data with longer follow up and 9 additional pts treated (total N=22) in this study. Methods This is a single arm, open-label phase I investigator-initiated study (NCT04935580). TE NDMM pts, aged between 18-70, and with one or more of the following features were considered eligible for the study: R-ISS-II or-III; del17p, t (4;14), t (14;16), or 1q21amp ≥ 4 copies; extramedullary disease (EM); IgD or IgE subtype; LDH > the upper limit of normal; or any of the high-risk definition of mSMART3.0. As of the data cutoff date, 22 evaluable pts (median age 59, range 43-69) are reported here. The median time from diagnosis to infusion was 100 days (range 63-152). All patients had one or more high-risk features including 91% R-ISS stage II or III, 55% with EM, 32% 1q21≥4 copies, and 9% IgD type. Of the 22 pts, 21 pts received 2 cycles induction therapy of bortezomib, lenalidomide and dexamethasone (VRd), and one patient received 1 cycle bortezomib, epirubicin, and dexamethasone (PAD) and 1 cycle VRd prior to the infusion. GC012F was administered as a single infusion at 3 doses levels (DL) of 1x10 5/kg (n=1), 2x10 5/kg (n=4), or 3x10 5/kg (n=17), after a standard 3-day lymphodepletion consisting of cyclophosphamide and fludarabine . Results As of June 9 th, 2023 data cutoff, 22 patients were enrolled and evaluable for safety and efficacy. Median follow-up was 13.6 months (range 2.1-23.9 months). Overall response rate (ORR) was 100% and stringent complete response (sCR) rate was 95.5%. All treated pts (100%) across all dose levels achieved minimal residual disease (MRD) negativity assessed by Euroflow (sensitivity of 10 -6). All evaluable pts achieved MRD negativity at Month 1, and maintained MRD- at landmark analysis of Month 6 and Month 12. Median duration of response (DOR) and progression-free survival (PFS) were not reached. Only 6 pts (27%) experience low-grade cytokine release syndrome (CRS), including 23% grade 1 (n=5) and 4% grade 2 (n=1). No treatment-related grade ≥3 CRS, nor ICANS of any grade, and nor deaths occurred in the study. Robust CAR T-cell expansion was observed in all pts; the median peak expansion (Cmax) was 62,131 (range: 8,754-331,159) copies /μg DNA with a median Tmax of 10 days (range 9-14 d). Conclusion Consistent with the previous RRMM cohort treated with GC012F, initial data from this phase I study demonstrated that BCMA-CD19 dual-targeting FasTCAR-T GC012F resulted in deep and durable response in transplant-eligible newly-diagnosed high-risk pts with a very favorable safety profile. All three dose groups achieved 100% MRD negativity and 100% ORR and sCR. The promising preliminary results achieved with GC012F demonstrate potential of CAR-T therapy in newly-diagnosed MM pts. Further research with larger patient population and longer follow-up shall bring the hope to this unmet medical need.

Talquetamab + Pomalidomide in Patients with Relapsed/Refractory Multiple Myeloma: Safety and Preliminary Efficacy Results from the Phase 1b MonumenTAL-2 Study

Introduction: Talquetamab (tal) is a T-cell redirecting bispecific antibody (BsAb) targeting GPRC5D and CD3. GPRC5D is a novel antigen that is highly expressed on malignant plasma cells but has low expression on B cells and normal plasma cells. Tal has demonstrated deep and durable responses, including in high-risk populations, and a clinically manageable safety profile in patients (pts) with relapsed/refractory multiple myeloma (RRMM) in the MonumenTAL-1 study (NCT03399799/NCT04634552). Pomalidomide (pom) is an established immunomodulatory drug (IMiD) that has direct on-tumor apoptotic activity and enhances immune activity. Combining pom with T-cell redirection therapy may lead to synergistic antimyeloma effects. We report initial efficacy and safety results of tal + pom from the MonumenTAL-2 study. Methods: MonumenTAL-2 (NCT05050097) is a multi-arm, phase 1b study of tal in combination with antimyeloma agents in pts with MM. Pts received the recommended phase 2 doses of subcutaneous tal 0.4 mg/kg weekly (QW) or 0.8 mg/kg every other week (Q2W), with step-up dosing, + oral pom 2 mg daily (dose escalation to 4 mg daily permitted) starting in cycle 2. Pts received ≥2 prior lines of therapy (LOT) including a proteasome inhibitor and an IMiD; prior T-cell redirection therapies including BsAbs and chimeric antigen receptor (CAR)-T along with prior pom exposure were permitted. CRS and ICANS were graded by ASTCT criteria; all other adverse events (AEs) were graded by CTCAE v5.0. Response was assessed by IMWG criteria. Efficacy endpoints are presented as individual cohorts (QW and Q2W); safety is presented across both cohorts. Results: As of June 5, 2023, 35 patients were enrolled with a median follow-up of 11.4 months (range, 1.2-14.9) in the QW cohort (N=16) and 7.7 months (range, 1.6-10.8) in the Q2W cohort (N=19). Median ages were 69.5 years (range, 49-78) and 63.0 years (range, 43-76), respectively; 41.7% and 33.3% of pts had high-risk cytogenetics (del[17p], t[4;14], or t[14;16]) and 12.5% and 10.5% of pts had extramedullary disease, respectively. Median prior LOT were 3 in both cohorts; 25.0% and 21.1% were triple-class refractory, respectively, and 6.3% were penta-drug refractory (all in QW cohort). Prior treatments included CAR-T (18.8% and 0%), BsAb (6.3% and 0% [0% refractory]), and anti-CD38 Ab (75.0% and 73.7% [56.3% and 36.8% refractory]) in the QW and Q2W cohorts, respectively; 31.3% and 15.8% had prior pom exposure (18.8% and 5.3% refractory). All pts had ≥1 AE; most common were dysgeusia (77.1%), CRS (74.3%; most grade 1/2, 2.9% grade ≥3), and neutropenia (60.0%). Grade 3/4 AEs occurred in 88.6% of pts; most common were neutropenia (48.6%), anemia (25.7%), and thrombocytopenia (20.0%). Nail, skin, and rash toxicities occurred in 65.7%, 40.0%, and 20.0% of pts (majority grade 1/2 with no discontinuations), respectively. ICANS occurred in 2 pts (both grade 1). Infections occurred in 71.4% of pts (22.9% grade 3/4); most common were pneumonia (20.0%) and COVID-19 (14.3%). AEs led to dose reduction or schedule change of tal in 34.3% of pts and dose reduction of pom in 31.4% of pts. Two pts (5.7%) in the Q2W cohort had AEs, myocardial infarction and pulmonary embolism (PE), that led to treatment discontinuation (not drug related). One death due to PE occurred (same pt who discontinued treatment). ORR was 86.7% and 83.3% in the QW and Q2W cohorts, respectively, with ≥CR in 60.0% and 44.4% and ≥VGPR in 86.7% and 77.8%, respectively. ORRs were consistent across pt subgroups (>80% independent of prior pom or CAR-T exposure). Median time to first response was 1.0 month (range, 0.9-2.1) in the QW cohort and 1.3 months (range, 0-4.8) in the Q2W cohort. At 6 months, 100% of responders were still responding in both cohorts. Median DOR and PFS were not reached, with 6-month PFS rates of 93.3% (QW) and 88.9% (Q2W). Conclusions: In this first reported combination of a GPRC5D-targeted therapy and an IMiD, tal + pom showed rapid, deep responses in pts with RRMM and ≥2 prior LOT. The safety profile of the combination, including grade 3/4 hematologic toxicity, was consistent with the individual agents, with no evidence of additive hematologic toxicities; additionally, there were low rates of treatment discontinuation due to AEs. The promising efficacy and manageable safety profile of this combination further supports tal as a versatile combination partner and warrants further evaluation of this regimen.

Correlation Revealed between Gemtuzumab-Ozogamicin Efficacy and CD33+ Expression in AML Primary Samples through a Novel AML in Vitro Model

Acute myeloid leukemia (AML) is one of the most difficult blood cancers to treat with increasing incidence in recent years. The disease is characterized by a clonal hematopoietic aggressive disorder of progenitor and stem cells. The prognosis for patients with AML is generally poor. After the first remission, most patients will develop recurrent disease, often within the first year 1. Recent molecular deconvolution of the mechanisms underlying AML disease have impacted the way AML patients are managed in the clinic, going from chemotherapy to the implementation of monoclonal antibodies and antibody-drug conjugates (ADC) 2. One of the limitations to ADC development for AML patients is the lack of AML-specific antigens. CD33 is a recent target which, although being expressed by other normal hematopoietic cells, is also strongly expressed in 80-90% of all AML cells. For these reasons gemtuzumab-ozogamicin (Mylotarg), a monoclonal antibody targeting CD33 covalently linked to the toxin calicheamicin, is the only FDA approved ADC for AML treatment 2. Although these treatments have had an impact on patient care, new therapeutic strategies are required to succeed in effectively treating AML. To date, several AML models have been exploited to predict patients' response 3. The model portfolio comprises in vivo and ex vivo models; however, the difficulties in culturing AML primary cells while maintaining clonal heterogeneity often limit the ability of the assay to recapitulate the disease. The development of a functional experimental model capable of mimicking the heterogeneity and complexity of AML with translational potential is still a major challenge. To overcome the lack of clinically relevant translational models that can stratify sensitive and resistant tumors across different treatments, we developed our proprietary assay, Champions AML VitroScreen ®, to test therapeutic candidates in primary AML samples 4. Our bank of primary, deeply characterized AML samples recapitulates the diversity of multiple AML subtypes from a phenotypic and molecular standpoint. This assay allows for evaluation of cell viability, proliferation, and clonal composition in response to therapeutic intervention using a variety of validated endpoint analyses. To challenge the robustness of the assay, we used the VitroScreen platform to test Mylotarg, in primary AML samples used as models for the different AML subtypes including M1, M2, M3, M4 and M5. To select appropriate AML models, we evaluated the expression of CD33 in AML blasts by high complexity flow cytometry. CD33+ high, intermediate, and low expressing models were included in the study. We measured the IC50 for Mylotarg in more than 20 AML models and correlated the marker expression with drug efficacy. Dose-dependent responses to Mylotarg were observed across multiple models by evaluating cell growth and viability using the CellTiter-Glo ® assay. As additional endpoints cell proliferation, apoptosis, and phenotyping by flow cytometry were included to better interpret Mylotarg mechanism of action. Based on the assay results, primary AML models were classified into different categories, respectively responder, low responder and resistant, based on the IC50 value, and a strong positive correlation between sensitivity to Mylotarg and CD33+ expression was found. The use of deeply characterized AML patient primary samples within the AML VitroScreen ® platform allowed for high throughput drug testing, which represents the ideal clinical translational setting in preclinical research. The use of this innovative system for patient selection and drug screening will support the development of new and tailored therapeutic strategies for patients with primary or recurrent AML, leading to improved patient outcomes.

Composition and Dynamic Evolution of the Bone Marrow Microenvironment in AL Amyloidosis during Daratumumab Based Therapy

Background: Immunoglobulin light chain (AL) amyloidosis is caused by clonal B or plasma cells proliferating in the bone marrow that produce immunoglobulin (MIg) proteins that misfold and aggregate in tissue(s), leading to multi-organ failure. The monoclonal antibody targeting CD38, daratumumab is an approved and very efficient treatment in multiple myeloma and AL Amyloidosis by inducing plasma cell death through immune mediated mechanisms including complement and antibody-dependent cytotoxicity, direct apoptosis and T cell subsets modifications. While the role of the bone marrow microenvironment (BME) as a major oncogenic actor in multiple myeloma (MM) is well established, the BME composition and role in AL Amyloidosis is largely undefined. Here, we used single-cell RNA-seq combined with CITE-seq and TCR sequencing to characterize the immune ecosystem and microenvironment in AL amyloidosis in comparison to healthy donors, as well as in comparison to other plasma cell disorders including monoclonal gammopathy of undetermined significance (MGUS), smoldering multiple myeloma (SMM) and multiple myeloma (MM). Methods: BM aspirates from 6 AL amyloidosis patients were collected at diagnosis or before treatment with daratumumab based therapy and 12 months post-treatment, alongside samples from 13 healthy donors, 5 MGUS, 9 SMM and 8 MM patients at diagnosis. We performed unbiased mRNA profiling (5' sequencing) and feature barcoding for cell surface proteins (CITE-seq) of bone marrow mononuclear cells using 10x Genomics. We processed data via the Cell Ranger pipeline, which grouped T cells into clonotypes based on shared TCR α/β sequences. Further data processing was done with Seurat, scRepertoire and Immunarch. Overall, 83703 cells were sequenced from 45 samples, including 3065 plasma cells and 80639 BME cells. Results: Compared to other plasma cell disorders (PCD) at diagnosis, AL BME had more cellular diversity and its plasma cells were more similar to normal plasma cells. They also had more TCR diversity than other PCD samples. When compared to healthy samples, AL BME had a trend towards more CD8+ T cells (p value = 0.078) at diagnosis, which became more pronounced 12 months post-treatment (p value = 0.012), and a trend towards fewer monocytes (p value = 0.036). When compared to PCD samples, AL BME tended to have more hematopoietic stem cells (p value = 0.018 vs MGUS, 0.052 vs SMM and 0.02 vs MM) and fewer NK cells (p values respectively 0.03, 0.059, 0.05) and CD4+ T cells (p values respectively 0.05, 0.018, 0.02) (Figure 1). The number of memory T cells and exhausted T cells were similar. Importantly, AL samples were significantly enriched in early/young CD4 memory T cells (p value < 2.6e-16) and NK/T like CD8+ T cells (p value = 7.99e-11) suggesting an ongoing and active T cell mediated immune response. We next analyzed serial samples from 4 AL patients at diagnosis and ~12 months after Daratumumab-based therapy, with half the patients achieving complete hematologic and organ responses (CR) and half with incomplete responses. We found broad changes in the BME, but in particular, there were more CD4+ and CD8+ T cells at 12 months expressing cytokine signaling genes (p value 1.19e-35) and adaptive immune system pathway genes (p value = 2.59e-33). Importantly, the distributions of CD8+ cells and T cell clonotypes were different between patients achieving CR and those who did not, underlying the role of the immune microenvironment and especially CD8+ T cells in the pathogenesis of the disease and response to Daratumumab based treatment. Conclusion: We identified unique characteristics of the BME in AL amyloidosis and dynamic changes within the T cell compartment following Daratumumab based therapy. Further validations are needed to evaluate the potential of BME profiling to diagnose the disease, predict treatment response and potentially develop new therapeutic strategies in AL Amyloidosis.

Daratumumab, Bortezomib, and Dexamethasone (D-Vd) Versus Bortezomib and Dexamethasone (Vd) Alone in Chinese Patients with Relapsed/Refractory Multiple Myeloma: Final Analysis of the Phase 3 Lepus Study

Introduction: Daratumumab is a human IgGκ monoclonal antibody targeting CD38 with a direct on-tumor and immunomodulatory mechanism of action. D-Vd prolonged progression-free survival (PFS) and induced deeper and more durable responses versus Vd alone in patients with relapsed/refractory multiple myeloma (RRMM) in the global phase 3 CASTOR study. A prior updated analysis of the phase 3 LEPUS study (median follow-up, 25.1 months) showed significant clinical benefit for D-Vd versus Vd in Chinese patients who have RRMM, and a safety profile generally consistent with that observed in CASTOR. Here, we report results from the final analysis of LEPUS with an extended median follow-up of >3 years. Methods: In the randomized, multicenter, phase 3 LEPUS study (ClinicalTrials.gov Identifier: NCT03234972), Chinese patients with RRMM who had received ≥1 prior line of therapy were randomized 2:1 to 8 cycles (21 days/cycle) of Vd (bortezomib 1.3 mg/m 2 SC on Days 1, 4, 8, and 11; dexamethasone 20 mg PO/IV on Days 1, 2, 4, 5, 8, 9, 11, and 12) ± daratumumab (16 mg/kg IV weekly in Cycles 1-3, every 3 weeks in Cycles 4-8, and every 4 weeks thereafter until disease progression). Per a protocol amendment, on Day 1 of any cycle patients receiving daratumumab IV were permitted to switch to daratumumab SC 1800 mg (same schedule as IV). The primary endpoint was PFS. Results: A total of 211 patients were randomized to D-Vd (n = 141) or Vd (n = 70). At a median follow-up of 37.1 months, D-Vd continued to prolong PFS versus Vd alone (median, 14.9 vs 6.3 months; hazard ratio [HR], 0.36; 95% confidence interval [CI], 0.25-0.52; P <0.00001; Figure 1). Time to progression (median, 15.7 vs 6.8 months; HR, 0.34; 95% CI, 0.23-0.51; P <0.00001) and overall survival (median, not reached vs 40.7 months; HR, 0.76; 95% CI, 0.50-1.17; P = 0.21; Figure 2) were longer with D-Vd versus Vd. The duration of response among patients who achieved a partial response or better was also longer with D-Vd versus Vd (median, 16.8 vs 9.0 months). The measurable residual disease-negativity rate (10 -5) was higher with D-Vd versus Vd (32.6% vs 4.3%; odds ratio, 10.81; 95% CI, 3.23-36.23; P <0.0001). The safety profile of D-Vd observed at the final analysis was generally consistent with that observed for the prior updated analysis. Grade 3/4 treatment-emergent adverse events (TEAEs) were primarily hematologic events. Grade 3/4 infections were reported for 77 (55.0%) patients who received D-Vd and 28 (41.2%) patients who received Vd; lung infection (30.7% vs 22.1%, respectively) was the only nonhematologic grade 3/4 TEAE reported in ≥20% of patients. For patients who received D-Vd and Vd, respectively, TEAEs were classified as serious for 76 (54.3%) and 27 (39.7%) patients, led to treatment discontinuation in 7 (5.0%) and 2 (2.9%) patients, and led to death in 6 (4.3%) and 7 (10.3%) patients. None of the 123 patients in the D-Vd group who had appropriate immunogenicity samples were positive for antibodies to daratumumab. A total of 31 patients in the D-Vd group switched from daratumumab IV to daratumumab SC during the study (after completion of bortezomib and dexamethasone); among these patients, 24 (77.4%) preferred SC administration, 2 (6.5%) preferred IV administration, and 5 (16.1%) had no preference. For the 24 patients who indicated they preferred daratumumab SC administration, key reasons for their preference included treatment administration time (83.3%), more comfortable administration process (70.8%), fewer administration-related reactions (45.8%), and less caregiver burden (25.0%). Among the 31 patients who switched to daratumumab SC, 6 (19.4%) patients experienced grade 3 TEAEs (most commonly hyperglycemia and hypokalemia, n = 2 each) and 2 (6.5%) patients experienced serious AEs (pyrexia and hyperglycemia, n = 1 each). Conclusions: In this final analysis of LEPUS with a median follow-up of >3 years, D-Vd continued to demonstrate substantial efficacy benefits versus Vd and the safety profile of D-Vd remained stable, with no new safety concerns identified. In addition, several patients switched their daratumumab administration from IV to SC, which was preferred by most patients who switched. These results further support the feasibility of daratumumab SC administration and the use of D-Vd as a standard of care in Chinese patients with RRMM who have received ≥1 prior line of therapy.

Phase I Study of FT538 + Daratumumab for Treatment of r/r AML

Introduction: Relapsed and refractory (r/r) acute myeloid leukemia (AML) remains an unmet need with immune-therapy based treatments such as hematopoietic stem cell transplantation (HSCT) providing the longest relapse-free survival (RFS). Natural Killer (NK cells) have been shown to effect lysis of AML cells, both in vitro and in vivo across multiple platforms. In particular, “adaptive” NK cells induced in vivo in HSCT recipients after CMV reactivation have been shown to confer an RFS advantage. These cells are characterized phenotypically by the expression of NKG2C, CD57, KIR and downregulation of CD38. CD38 is an ectoenzyme broadly expressed on hematopoietic cells, including approximately 60% of AML. It catalyzes the conversion of nicotinamide-adenine dinucleotide (NAD+) and nicotinamide-adenine dinucleotide phosphate (NADP+) to cyclic adenosine diphosphate (cADP) ribosyl. CD38 knock-out NK cells have increased persistence by having enhanced metabolic fitness and resistance to oxidative stress via a reduction of reactive oxygen species. FT538 is an iPSC-derived NK cell product with a non-cleavable CD16 receptor to augment antibody-dependent cytotoxicity (ADCC), IL-15/IL-15R fusion to increase activation and persistence, and CD38 knockout to enhance its metabolic fitness and avoid fratricide when combined with CD38 monoclonal antibodies. Daratumumab (Dara) is a monoclonal antibody targeting CD38 on the surface of AML cells as well as activated lymphocytes. We hypothesized that the addition of Dara to fludarabine and cyclophosphamide would enhance lymphodepletion and augment ADCC for CD38+ AML leading to better response rates when combined with FT538. Methods: This (NCT04714372) is a phase I, dose-escalation study, utilizing FT538 in combination with fludarabine, cyclophosphamide, and Dara for the treatment of r/r AML. A study schema is presented in Figure 1A. Patients received 5 weekly doses of Dara starting day -12, 2 doses of fludarabine and cyclophosphamide at day -4, and 3 weekly doses of FT538. They were followed for DLT for 28 days after FT538 infusion. Patients with r/r AML after 2 or more lines of therapy and good organ function were enrolled. The primary objective was the safety of this combination, and the endpoints were the incidence of dose-limiting toxicities (DLTs) and incidence of adverse events. Secondary endpoint was the efficacy and predictors of efficacy. Patients evaluable for safety are those who received at least one dose of FT538. Patients evaluable for efficacy are those who completed all doses. Fast-track enrollment was utilized where one patient per dosing level (DL) was enrolled as long as no DLTs were seen with cohort expansion in the event of DLTs or related severe adverse events. Results: Six patients were enrolled on 4 DLs with increasing dose of FT538 from 1x10 8 - 1.5x10 9 cells. Median age was 70 years. Median number of prior lines is 3.5 (3-4). All patients were refractory to most recent therapy. One patient was enrolled on each DL1, DL2, and DL3. Three enrolled on DL4 with 1 completing therapy. Five patients are evaluable for safety and 4 for efficacy. There were no DLTs and we were able to enroll one patient per cohort. Eighty percent (4/5) experienced febrile neutropenia and infections. One patient with a prior biliary stent had choledocholithiasis requiring a complicated intervention. No prolonged cytopenias attributable to FT538 were seen. One patient experienced a G1 CRS lasting 1 day. There were no neurotoxicity events. One patient on DL2 achieved stable disease and one patient on DL4 achieved a CR for an ORR of 50% (2/4). Both went on to receive HSCT and continue to be alive and well without disease with a median follow up of 5 months. This is summarized in Figure 1.B. Macrochimerism (donor cells) was detected for up to 8 days post-infusion. Macrochimerism did not correlate with response but did show that Ki67 expression was present on donor cells suggesting proliferation. Conclusions: FT538 in combination with daratumumab has been tolerated in a highly pre-treated cohort of patients with expected toxicities and a signal of efficacy.

Real-World Analysis of Treatment Patterns and the Effectiveness and Safety Profile of Daratumumab-Based Regimens in Chinese Patients with Newly Diagnosed or Relapsed/Refractory Multiple Myeloma

Introduction: Daratumumab (DARA) is a human IgGκ monoclonal antibody targeting CD38 with a direct on-tumor and immunomodulatory mechanism of action. Several clinical trials have established DARA-based treatment as a standard of care globally for patients with newly diagnosed or relapsed/refractory multiple myeloma (MM). However, clinical trials do not always reflect routine clinical practice, and real-world (RW) studies thus provide an important complement to conventional clinical trials. Herein, we report results from an observational study that described RW treatment patterns and outcomes in routine clinical practice among patients with MM who were treated with DARA in China. This is possibly the first study to enroll a large population of Chinese patients with MM who were treated with DARA in the RW setting. Methods: This ongoing, multicenter, noninterventional, observational registry study is enrolling Chinese patients who have been diagnosed with symptomatic newly diagnosed or relapsed/refractory MM and either (1) started DARA treatment after August 1, 2019, and were expected to continue ongoing DARA at the time of study initiation (November 3, 2021) or (2) started DARA treatment after study initiation. Patients were excluded from the study if they had received ≥4 prior lines of MM therapy before starting DARA-based treatment or had a diagnosis of other cancers prior to their MM diagnosis. The decision to treat with DARA must have been made prior to and independently of the patient's inclusion in the study, and treatment was administered in accordance with local clinical practice. For patients who started DARA after August 1, 2019, but before study initiation, data were collected both retrospectively through medical chart review and prospectively after enrollment. RW baseline disease characteristics, treatment patterns, response rates, measurable residual disease (MRD), and safety are presented. Outcome and safety analyses were based on the DARA treatment period. Results: As of the cutoff date (April 30, 2023) for this analysis, 210 patients who received ≥1 dose of DARA have been enrolled in the study from 13 participating sites in China. At baseline (last status prior to the first DARA dose), patients had a median age of 64 y (range, 29-89) and a median time since MM diagnosis of 1 y (range, 0-12); the majority of patients had an ECOG performance status of 0 or 1 (82.4%) and a Durie-Salmon MM stage of III (74.4%). Most (83.8%) patients had received ≥1 prior line of therapy before initiating DARA, including 82.4% who had received prior protease inhibitors (PIs) and 58.1% who had received prior immunomodulatory drugs (IMiDs). A summary of prior therapies is provided in Table 1. DARA-based therapy included DARA monotherapy (n = 22) or combination with dexamethasone only (n = 21), PIs ± dexamethasone (n = 57), IMiDs ± dexamethasone (n = 71), PIs and IMiDs ± dexamethasone (n = 29), and other combinations (n = 10). The median DARA exposure time was 5.39 mo (interquartile range [IQR], 2.56-9.69), and the median follow-up time was 10.48 mo (IQR, 7.23-15.31). Of the 179 patients evaluable for response, a best overall response of partial response (PR) or better was achieved by 130 (72.6%) patients and a best response of very good partial response (VGPR) or better was achieved by 93 (52.0%) patients, with responses observed across DARA treatment regimens ( Table 2). MRD results were available for 53/179 (29.6%) patients, with 31/53 (58.5%) patients achieving MRD negativity. Adverse drug reactions were reported for 40 (19.0%) patients overall; events reported in ≥5% of patients included leukopenia (6.2%), thrombocytopenia (5.7%), and neutropenia (5.2%). Serious treatment-emergent adverse events were reported for 29 (13.8%) patients, with pneumonia (n = 10, 4.8%) the only serious event reported in ≥5 patients. Twenty-five patients died as of the cut-off date, regardless of timing (with/without DARA treatment period). Conclusions: This noninterventional, observational study provides RW insights into physician treatment decisions for patients with MM in China and the characteristics of patients who are selected for DARA-based treatment. In addition, the RW effectiveness, duration of therapy, and safety results support the use of DARA-based treatment as a standard of care in Chinese patients with newly diagnosed or relapsed/refractory MM. This study is ongoing, with a total planned enrollment of ~220 patients.

Efficacy and Safety of Daratumumab (DARA) Monotherapy in Patients with Intermediate-Risk or High-Risk Smoldering Multiple Myeloma (SMM): Final Analysis of the Phase 2 Centaurus Study

Introduction: SMM is a precursor disorder to multiple myeloma (MM) (Rajkumar SV, et al. Blood. 2015;125[20]:3069-3075). Current guidelines for SMM recommend active monitoring, with treatment initiation only upon progression to MM. However, therapeutic intervention at the SMM stage may help delay the progression to MM (Lonial S, et al. J Clin Oncol. 2020;38[11]:1126-1137; Mateos MV, et al. ASH 2022. Abstract 118). DARA is a human IgGκ monoclonal antibody targeting CD38 with a direct on-tumor and immunomodulatory mechanism of action. Given the deep and durable responses and favorable safety profile of DARA monotherapy in patients (pts) with relapsed/refractory MM (Usmani SZ, et al. Blood. 2016;128[1]:37-44), we hypothesized that DARA could delay the progression of SMM to MM. In the primary analysis of the phase 2 CENTAURUS study (NCT02316106), after a 15.8-month median follow-up, DARA monotherapy showed activity and was well tolerated in pts with intermediate- or high-risk SMM (Landgren CO, et al. Leukemia. 2020;34[7]:1840-1852). Activity and tolerability of DARA monotherapy were also observed in CENTAURUS after an additional 10 months of median follow-up (Landgren CO, et al. ASH 2018. Abstract 1994). Here, we present the final analysis of the CENTAURUS study, with a median follow-up of 85.2 months (~7 years). Methods: Eligible pts had a diagnosis of intermediate-risk or high-risk SMM for <5 years. Pts were randomized (1:1:1) to receive 8-week cycles of DARA 16 mg/kg intravenously (IV) on 1 of 3 dosing schedules. In the Intense dosing arm, pts received DARA QW (Cycle 1), Q2W (Cycles 2-3), Q4W (Cycles 4-7), and Q8W (Cycles 8-20). In the Intermediate dosing arm, pts received DARA QW (Cycle 1) and Q8W (Cycles 2-20). In the Short dosing arm, pts received 1 cycle of DARA QW. For pts in the Intense and Intermediate arms, there was an option to extend treatment (Extension phase) with DARA IV or with subcutaneous DARA (DARA SC; DARA 1,800 mg co-formulated with recombinant human hyaluronidase PH20 [2,000 U/mL; Halozyme, Inc.]) Q8W after the end of Cycle 20 per investigator discretion if there was a positive benefit/risk ratio, no grade ≥3 treatment-related toxicity, and at least stable disease had been achieved. Rate of complete response or better (≥CR) was a primary endpoint. Secondary endpoints included overall response rate (ORR) and overall survival (OS). Results: A total of 123 pts (41 pts per arm) were randomized. Median (range) age was 61 (31-81) years. Median duration of study treatment overall during the study was 44.0 months in the Intense arm, 35.2 months in the Intermediate arm, and 1.6 months in the Short arm. A total of 36 pts (21 pts in the Intense arm and 15 pts in the Intermediate arm) continued to receive DARA Q8W in the Extension phase (Cycles 21+). During the Extension phase, median duration of study treatment was 45.2 months in the Intense arm and 46.1 months in the Intermediate arm ( Table 1). 16 pts in the Intense arm and 10 pts in the Intermediate arm switched from DARA IV to DARA SC during the Extension phase. Efficacy results are summarized in Table 2. At a median (range) follow-up of 85.2 (0-94.3) months, ORR and ≥CR rate were higher in the Intense and Intermediate arms than in the Short arm. In the Intense and Intermediate arms combined, the ≥CR rate was 8.5%. Median OS was not reached in any dosing arm; the 84-month OS rate was 81.3%, 89.5%, and 88.1% in the Intense, Intermediate, and Short arms, respectively. Safety results are summarized in Table 1. Grade 3/4 treatment-emergent adverse events (TEAEs) occurred in 65.9%, 41.5%, and 15.0% of pts in the Intense, Intermediate, and Short arms, respectively; grade 3/4 TEAEs were reasonably related to DARA in 12.2%, 2.4%, and 5.0% of pts, respectively. TEAEs that led to discontinuation of DARA occurred in 7.3%, 2.4%, and 5.0% of pts in the Intense, Intermediate, and Short arms, respectively. Conclusions: Findings from this final analysis of CENTAURUS continue to demonstrate the clinical activity of DARA monotherapy in pts with intermediate- or high-risk SMM after a median follow-up of ~7 years. A high proportion (44%) of pts in the Intense and Intermediate arms completed 20 cycles and remained on DARA monotherapy per investigator discretion, with a median duration of additional treatment of 46.0 months (~4 years) in the Extension phase. No new safety concerns were observed with extended follow-up.

Dose Escalation of HLA-A2-WT1 CD3 T-Cell Bispecific Antibody in a Phase I Study in Patients with Relapsed/Refractory Acute Myeloid Leukemia (AML)

Background: RO7283420 (RG6007) is a 2+1 TCR-like (TCR-L) T-cell bispecific (TCB) antibody targeting CD3 and the RMFPNAPYL peptide of Wilms Tumor 1 (WT1) protein presented by the major histocompatibility complex-I HLA-A*02 on acute myeloid leukemia (AML) blasts and other antigen presenting cells. The pre-clinical evaluation of RO7283420 in our in vivo humanized AML xenografts and ex vivo AML co-culture models showed strong T-cell mediated AML cell killing (Augsberger C, et al. Blood 2021). A Phase 1 dose-escalation (DE) study (NCT04580121) evaluated the safety, tolerability, pharmacokinetics, anti-drug antibodies (ADAs), and anti-leukemic activity of RO7283420 in patients with relapsed/refractory (R/R) AML. Methods: In this open-label, multi-center study, DE was performed using a 3+3 design. Patients received RO7283420 every 3 weeks (Q3W, n=46), or every week (QW, n=4) as intravenous (IV) infusions. Preliminary anti-leukemic activity included response assessment according to European Leukemia Net (ELN) response categories (adapted from Döhner H, et al. Blood 2017). Results: As of 13 April 2023, 50 HLA-A2+ R/R AML patients received at least one dose of RO7283420. Patients had a median age of 65.5 years (range 35-84), presented with ECOG of 0 (56%) or 1 (38%) or 2 (6%), and 58% were male. Median prior line of therapy was 2 (range 1-5). Overall, 58% of patients had relapsed and 42% had primary refractory disease. According to the ELN 2017 risk stratification, patients were of adverse (48%), intermediate (38%) or favorable (8%) risk category, for 6% of patients the risk category missing. The most common genetic abnormalities reported were RUNX1 (21%), ASXL1 (17%), TP53 (10.6%), FLT3-ITD (6.4%) and NPM1 (6.4%) of the 47 patients tested. Median bone marrow blast percentage at baseline was 35% (range 3-90%), while the median of circulating blast was 17% (range 0-88%). Study patients received RO7283420 IV at 13 different dose levels, ranging from a Minimum Anticipated Biological Effect Level (MABEL) of 0.15 mg (flat) to 18 mg Q3W (with a preceding weekly 1/3 mg ‘double step-up’ during Cycle 1) and one QW dose level with 9 mg preceded by a 1/3 mg step-up. Maximum tolerated dose was reached at 1/3/12 mg double step-up Q3W. Explored alternative QW schedule was not tolerable at 1/3/9 mg. The most common (≥20%) adverse events (AEs) were cytokine release syndrome (CRS) occurring in 34 (68%), pneumonia 14 (28%), pyrexia 13 (26%), febrile neutropenia 13 (26%), hyperglycemia 12 (24%), hypokalemia 11 (22%), and nausea 10 (20%) of patients. Eight dose limiting toxicities (DLTs) were reported: five G3 CRS (at 1/3, 2/12, 1/6/12 mg dose levels), G3 stomatitis (at 1/3/12 mg), G3 myositis (at 1/3/18 mg), and G4 thrombocytopenia (at 1/3/18 mg). Eleven patients (22%) experienced Grade 5 AEs with pneumonia, sepsis, and hemophagocytic lymphohistiocytosis (HLH) reported in >1 patient; all Grade 5 events were considered unrelated to RO728342 except 1 (at 1/3/9 mg) of 2 HLH events. IV PK has been overall dose-linear and characterized by a terminal half-life of 29 to 84 hours and a clearance of 58 to 92 mL/h. Preliminary ADA incidence within the study population was 19%. In the dose ranges tested, a trend for study drug exposure-dependent blast reduction was observed in blood, while a clear exposure-response relationship could not be established with BM blast reduction. Furthermore, our preliminary pharmacodynamic analysis identified expansion of naive and memory CD8 T cells in blood and activated CD8+ T cells in bone marrow, in line with the expected mode of action (MoA) of RO7283420. Preliminary efficacy signals were observed with 3 complete responses (CR), including 1 CR with incomplete blood count recovery. Conclusions: RO7283420 is the first TCR-L TCB antibody evaluated in AML. We observed pharmacodynamic evidence of T-cell activation and expansion in the clinic, in line with the expected MoA of TCBs, however, at the explored doses, no clear exposure-response relationship and only a modest clinical activity were observed. The safety profile was shown to be consistent with the other TCBs and R/R AML population. Based on the totality of data, the study was discontinued.

Antibody and immunotherapy in diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) is the most common lymphoma and a heterogeneous B-cell disease. The majority of patients with newly diagnosed disease are cured with first-line combination immunochemotherapy treatment however, those who experience treatment failure have dismal outcomes. Antibody therapies and immunotherapy have provided the single most major advance in the treatment of DLBCL in the last 4 decades. Rituximab, the first immunotherapy, and a monoclonal antibody targeting CD20, improved DLBCL overall survival when added to chemotherapy 2 decades ago. Since then, the advent of further "naked" monoclonal antibodies that target malignant B-cells or stimulate the immune system to kill cancer, as well as antibody-drug conjugates and bispecific antibodies have all entered the DLBCL armamentarium; with 5 antibody therapy approvals in the last 6 years alone. Here we review the literature on antibodies and immunotherapies for DLBCL and the future directions involving this successful group of drugs.

Talquetamab in multiple myeloma.

Initial results of the phase I trial of talquetamab, a bispecific antibody targeting GPRC5D and CD3, were reported in December of 2022 for the treatment of relapsed or refractory multiple myeloma in the fourth line or later setting. It demonstrated a similar efficacy profile and durability of response to teclistamab, the first bispecific antibody therapy to be approved in multiple myeloma. Additionally, it has less infections than teclistamab but demonstrates unique class-specific side effects including skin, oral, and nail-related adverse events. Despite this, it is still a highly efficacious and well-tolerated therapy that will add to the armamentarium of therapeutics against heavily pretreated multiple myeloma.

Immune reconstitution following alemtuzumab therapy is characterized by exhausted T cells, increased regulatory control of proinflammatory T cells and reduced B cell control.

Alemtuzumab is a monoclonal antibody targeting CD52 on the surface of immune cells, approved for the treatment of active relapsing-remitting multiple sclerosis (RRMS). The purpose of this study was to analyze the repopulation of peripheral lymphocytes following alemtuzumab-induced lymphocyte depletion and investigate associations with disease activity and development of secondary autoimmunity. For this, blood samples were collected two years after initiation of alemtuzumab treatment and lymphocytes were subjected to a comprehensive flow cytometry analysis. Included in the study were 40 patients treated with alemtuzumab and 40 treatment-naïve patients with RRMS. Disease activity and development of secondary autoimmune disease was evaluated after three years of treatment. Our study confirms that alemtuzumab treatment profoundly alters the circulating lymphocyte phenotype and describes a reconstituted immune system characterized by T cell activation/exhaustion, an increased regulatory control of IL-17 producing effector T cells and CD20+ T cells, and a reduced control of B cells. There were no obvious associations between immune cell subsets and disease activity or development of secondary autoimmune disease during treatment with alemtuzumab. Our results indicate that the reconstituted immune response is skewed towards a more effective regulatory control of MS-associated proinflammatory T cell responses. Also, the enlarged pool of naïve B cells together with the apparent decrease in control of B cell activity may explain why alemtuzumab-treated patients retain the ability to mount a humoral immune response towards new antigens.

P-136 Phase I open-label single-arm study of dual targeting BCMA and CD19 FasTCAR-T cells (GC012F) as first-line therapy for transplant-eligible newly diagnosed high-risk multiple myeloma

P-136 Phase I open-label single-arm study of dual targeting BCMA and CD19 FasTCAR-T cells (GC012F) as first-line therapy for transplant-eligible newly diagnosed high-risk multiple myeloma

Knowing Your Target: Altered Mental Status From an Unsuspected Source

Daratumumab is a human monoclonal antibody targeting CD38 that is used in the treatment of multiple myeloma. In addition to being a target for cancer-related treatment, CD38 also plays a significant role in the immune response to infection. CD38 deficiency can increase susceptibility to several bacterial infections. This article discusses the case of a 52-year-old female with a history of IgG multiple myeloma status post autologous stem cell transplant with relapse who was receiving therapy with daratumumab, lenalidomide, and dexamethasone. She presented to the emergency department with a history of 3 to 4 days of generalized weakness, poor appetite, nausea, vomiting, watery stools, and fevers. Her symptoms did not improve with initial fluid resuscitation and broad-spectrum antimicrobials; instead, she experienced progressive neurological decline. This case illustrates how utilizing targets for cancer-directed treatments can also affect immune function, which may leave patients susceptible to unique infections that may not otherwise be commonly encountered. Therefore, advanced practitioners must understand the functional role of these targets and the sequelae that could occur when expression is altered by pharmacological therapies to allow for expeditious recognition and management.

Mechanisms and Clinical Research Progress of Rituximab in the Treatment of Adult Minimal Change Disease

Introduction: Minimal change disease (MCD) is a common subtype of primary nephrotic syndrome in adults. The pathogenesis of MCD is still not well understood, but some studies suggest that MCD is a T cell-mediated disease related to podocyte dysfunction. Previous research has also indicated the crucial role of B cells in the pathogenesis of MCD. Rituximab (RTX) is a recombinant chimeric mouse/human antibody targeting CD20 antigen. In recent years, RTX has been increasingly used in adult MCD patients. Methodology: We searched the PubMed database using the keywords “Minimal change disease”, “Nephrotic syndrome”, and “Rituximab” and obtained a total of 140 articles. We will now provide a literature review based on these 140 articles, according to our research topic. Discussion: This article provides an overview of the mechanisms and clinical research progress of RTX in the treatment of adult MCD. We have also discussed the current treatment methods for MCD, exploring the potential of using RTX as a first-line therapy for refractory adult MCD. Conclusion: MCD is a common pathological type of nephrotic syndrome, and the exact mechanisms are still not fully understood. Although RTX as a treatment of adult MCD has shown promising clinical results in patients with refractory adult MCD, the safety and efficacy of RTX still lack high-quality clinical evidence. Further research is needed to explore the pathogenesis of MCD and the RTX treatment for MCD.