Sequential CD19 and CD22 chimeric antigen receptor T-cell therapy for childhood refractory or relapsed B-cell acute lymphocytic leukaemia: a single-arm, phase 2 study.

BACKGROUND: Relapses frequently occur following CD19-directed chimeric antigen receptor (CAR) T-cell treatment for relapsed or refractory B-cell acute lymphocytic leukaemia in children. We aimed to assess the activity and safety of sequential CD19-directed and CD22-directed CAR T-cell treatments. METHODS: This single-centre, single-arm, phase 2 trial, done at Beijing GoBroad Boren Hospital, Beijing, China, included patients aged 1-18 years who had relapsed or refractory B-cell acute lymphocytic leukaemia with CD19 and CD22 positivity greater than 95% and an Eastern Cooperative Oncology Group performance status of 0-2. Patients were initially infused with CD19-directed CAR T cells intravenously, followed by CD22-directed CAR T-cell infusion after minimal residual disease-negative complete remission (or complete remission with incomplete haematological recovery) was reached and all adverse events (except haematological adverse events) were grade 2 or better. The target dose for each infusion was 0·5 × 106 to 5·0 × 106 cells per kg. The primary endpoint was objective response rate at 3 months after the first infusion. Secondary endpoints were duration of remission, event-free survival, disease-free survival, overall survival, safety, pharmacokinetics, and B-cell quantification. The prespecified activity analysis included patients who received the target dose and the safety analysis included all treated patients. This study is registered with ClinicalTrials.gov, NCT04340154, and enrolment has ended. FINDINGS: Between May 28, 2020, and Aug 16, 2022, 81 participants were enrolled, of whom 31 (38%) were female and 50 (62%) were male. Median age was 8 years (IQR 6-10), all patients were Asian. All 81 patients received the first infusion and 79 (98%) patients received sequential infusions, CD19-directed CAR T cells at a median dose of 2·7 × 106 per kg (IQR 1·1 × 106 to 3·7 × 106) and CD22-directed CAR T cells at a median dose of 2·2 × 106 per kg (1·1 × 106 to 3·7 × 106), with a median interval of 39 days (37-41) between the two infusions. 62 (77%) patients received the target dose, including two patients who did not receive CD22 CAR T cells. At 3 months, 60 (97%, 95% CI 89-100) of the 62 patients who received the target dose had an objective response. Median follow-up was 17·7 months (IQR 11·4-20·9). 18-month event-free survival for patients who received the target dose was 79% (95% CI 66-91), duration of remission was 80% (68-92), and disease-free survival was 80% (68-92) with transplantation censoring; overall survival was 96% (91-100). Common adverse events of grade 3 or 4 between CD19-directed CAR T-cell infusion and 30 days after CD22-directed CAR T-cell infusion included cytopenias (64 [79%] of 81 patients), cytokine release syndrome (15 [19%]), neurotoxicity (four [5%]), and infections (five [6%]). Non-haematological adverse events of grade 3 or worse more than 30 days after CD22-directed CAR T-cell infusion occurred in six (8%) of 79 patients. No treatment-related deaths occurred. CAR T-cell expansion was observed in all patients, with a median peak at 9 days (IQR 7-14) after CD19-directed and 12 days (10-15) after CD22-directed CAR T-cell infusion. At data cutoff, 35 (45%) of 77 evaluable patients had CAR transgenes and 59 (77%) had B-cell aplasia. INTERPRETATION: This sequential strategy induced deep and sustained responses with an acceptable toxicity profile, and thus potentially provides long-term benefits for children with this condition. FUNDING: The National Key Research & Development Program of China, the CAMS Innovation Fund for Medical Sciences (CIFMS), and the Non-Profit Central Research Institute Fund of Chinese Academy of Medical Sciences. TRANSLATION: For the Chinese translation of the abstract see Supplementary Materials section.

CD22-targeted CD28 bispecific antibody enhances antitumor efficacy of odronextamab in refractory diffuse large B cell lymphoma models.

Although many patients with diffuse large B cell lymphoma (DLBCL) may achieve a complete response to frontline chemoimmunotherapy, patients with relapsed/refractory disease typically have poor outcomes. Odronextamab, a CD20xCD3 bispecific antibody that provides "signal 1" through the activation of the T cell receptor/CD3 complex, has exhibited early, promising activity for patients with highly refractory DLBCL in phase 1 trials. However, not all patients achieve complete responses, and many relapse, thus representing a high unmet medical need. Here, we investigated whether adding a costimulatory "signal 2" by engaging CD28 receptors on T cells could augment odronextamab activity. We demonstrate that REGN5837, a bispecific antibody that cross-links CD22-expressing tumor cells with CD28-expressing T cells, enhances odronextamab by potentiating T cell activation and cytolytic function. In preclinical DLBCL studies using human immune system-reconstituted animals, REGN5837 promotes the antitumor activity of odronextamab and induces intratumoral expansion of reprogrammable T cells while skewing away from a dysfunctional state. Although REGN5837 monotherapy shows limited activity and no toxicity in primate studies, it augments T cell activation when dosed in combination with odronextamab. In addition, analysis of non-Hodgkin lymphoma clinical samples reveals an increase in CD28+CD8+ T cells after odronextamab treatment, demonstrating the presence of a population that could potentially be targeted by REGN5837. Collectively, our data demonstrate that REGN5837 can markedly enhance the antitumor activity of odronextamab in preclinical NHL models, and the combination of these two bispecific antibodies may provide a chemotherapy-free approach for the treatment of DLBCL.

A phase I study of inotuzumab ozogamicin as a single agent in pediatric patients in Japan with relapsed/refractory CD22-positive acute lymphoblastic leukemia (INO-Ped-ALL-1).

Inotuzumab ozogamicin (InO) is a CD22-directed antibody conjugated with calicheamicin approved for adult relapsed or refractory CD22-positive acute lymphoblastic leukemia (ALL). This phase 1 study primarily aimed to determine the pediatric recommended doses of InO through the standard 3 + 3 design, and to evaluate the safety, tolerability, pharmacokinetic (PK) profile, immunogenicity and efficacy of InO. Dose level 1 (DL1) was 1.8 mg/m2 (days 1, 8, and 15: 0.8, 0.5, and 0.5 mg/m2, respectively). Six of the seven registered patients were eligible [median age, 7.5 (2-17) years]. Although all six patients started DL1, only five completed the dose. No dose-limiting toxicity was observed. All patients experienced adverse events (AEs), including increased alanine aminotransferase and aspartate aminotransferase in four patients. Three patients experienced serious AEs, which were hepatic veno-occlusive disease (VOD), ALL, and fever. Five patients achieved complete remission (CR) or CR with incomplete blood cell recovery (CRi), among whom 3 (60%) were negative for minimal residual disease. PK findings were similar to those in adults. No patient had anti-drug antibodies to InO. In conclusion, InO was well tolerated in children and promoted similar antileukemic efficacy as in adults. Nonetheless, the risk for VOD requires attention.

Splicing-Mediated Antigen Escape from Immunotherapy for B-cell Malignancies.

SUMMARY: In this issue of Blood Cancer Discovery, Zheng and colleagues identify that alternative RNA splicing of CD22 within B-cell acute lymphoblastic leukemia can result in antigen escape from CD22-targeted immunotherapies. Drug-resistant isoforms of CD22 exist within leukemic cells pretreatment and can influence response to the CD22-directed antibody-drug conjugate inotuzumab ozogamicin, the immunotoxin moxetumomab pasudotox, as well as anti-CD22 chimeric antigen receptor T cells. See related article by Zheng et al., p. 103 (7).

SM03, an anti-human CD22 monoclonal antibody, for active rheumatoid arthritis: a phase II, randomized, double-blind, placebo-controlled study.

OBJECTIVE: SM03, a novel chimaeric mAb specific to B cell-restricted antigen CD22, has been developed to treat RA and other B-cell-related diseases. This 24-week phase II randomized, double-blind, multi-dose, placebo-controlled study aimed to evaluate the efficacy and safety of SM03 in moderately-to-severely active RA patients in China. METHODS: One hundred and fifty-six patients on background MTX were randomized in a 1:1:1 ratio to receive a cumulative dose of 3600 mg (high dose, 600 mg × 6 infusions at weeks 0, 2, 4, 12, 14 and 16) or 2400 mg SM03 (low dose, 600 mg × 4 infusions at weeks 0, 2, 12 and 14) or the placebo. The primary outcome was the 24-week ACR 20% improvement criteria (ACR20) response rate. Safety was also assessed. RESULTS: The 24-week ACR20 response rate was significantly higher with high- (65.3%, P = 0.002) and low-dose SM03 (56.9%, P = 0.024) than with placebo (34.0%), but comparable between the high- and low-dose group. The rate of adverse events was not statistically different among the high-dose group (35.3%), the low-dose group (51.9%) and the placebo group (34.6%). Thirteen (12.6%) patients receiving SM03 reported treatment-emergent infections, including 3.9% patients in the high-dose group. No patients reported severe treatment-emergent infections or malignancies. CONCLUSIONS: In active RA Chinese patients receiving background MTX, SM03 at a cumulative dose of both 2400 mg and 3600 mg is efficacious and well-tolerated throughout the 24 weeks of treatment. Moreover, SM03 has demonstrated a good safety profile. TRIAL REGISTRATION: ClinicalTrials.gov, https://clinicaltrials.gov, NCT04192617.

The CD22-IGF2R interaction is a therapeutic target for microglial lysosome dysfunction in Niemann-Pick type C.

Lysosome dysfunction is a shared feature of rare lysosomal storage diseases and common age-related neurodegenerative diseases. Microglia, the brain-resident macrophages, are particularly vulnerable to lysosome dysfunction because of the phagocytic stress of clearing dying neurons, myelin, and debris. CD22 is a negative regulator of microglial homeostasis in the aging mouse brain, and soluble CD22 (sCD22) is increased in the cerebrospinal fluid of patients with Niemann-Pick type C disease (NPC). However, the role of CD22 in the human brain remains unknown. In contrast to previous findings in mice, here, we show that CD22 is expressed by oligodendrocytes in the human brain and binds to sialic acid­dependent ligands on microglia. Using unbiased genetic and proteomic screens, we identify insulin-like growth factor 2 receptor (IGF2R) as the binding partner of sCD22 on human myeloid cells. Targeted truncation of IGF2R revealed that sCD22 docks near critical mannose 6-phosphate­binding domains, where it disrupts lysosomal protein trafficking. Interfering with the sCD22-IGF2R interaction using CD22 blocking antibodies ameliorated lysosome dysfunction in human NPC1 mutant induced pluripotent stem cell­derived microglia-like cells without harming oligodendrocytes in vitro. These findings reinforce the differences between mouse and human microglia and provide a candidate microglia-directed immunotherapeutic to treat NPC.

Preclinical to Clinical Translation of Antibody-Drug Conjugates Using PK/PD Modeling: a Retrospective Analysis of Inotuzumab Ozogamicin.

A mechanism-based pharmacokinetic/pharmacodynamic (PK/PD) model was used for preclinical to clinical translation of inotuzumab ozogamicin, a CD22-targeting antibody-drug conjugate (ADC) for B cell malignancies including non-Hodgkin's lymphoma (NHL) and acute lymphocytic leukemia (ALL). Preclinical data was integrated in a PK/PD model which included (1) a plasma PK model characterizing disposition and clearance of inotuzumab ozogamicin and its released payload N-Ac-γ-calicheamicin DMH, (2) a tumor disposition model describing ADC diffusion into the tumor extracellular environment, (3) a cellular model describing inotuzumab ozogamicin binding to CD22, internalization, intracellular N-Ac-γ-calicheamicin DMH release, binding to DNA, or efflux from the tumor cell, and (4) tumor growth and inhibition in mouse xenograft models. The preclinical model was translated to the clinic by incorporating human PK for inotuzumab ozogamicin and clinically relevant tumor volumes, tumor growth rates, and values for CD22 expression in the relevant patient populations. The resulting stochastic models predicted progression-free survival (PFS) rates for inotuzumab ozogamicin in patients comparable to the observed clinical results. The model suggested that a fractionated dosing regimen is superior to a conventional dosing regimen for ALL but not for NHL. Simulations indicated that tumor growth is a highly sensitive parameter and predictive of successful outcome. Inotuzumab ozogamicin PK and N-Ac-γ-calicheamicin DMH efflux are also sensitive parameters and would be considered more useful predictors of outcome than CD22 receptor expression. In summary, a multiscale, mechanism-based model has been developed for inotuzumab ozogamicin, which can integrate preclinical biomeasures and PK/PD data to predict clinical response.

Therapeutic potential of CD22-specific antibody-targeted chemotherapy using inotuzumab ozogamicin (CMC-544) for the treatment of acute lymphoblastic leukemia.

CMC-544 (inotuzumab ozogamicin) is a CD22-specific cytotoxic immunoconjugate of calicheamicin intended for the treatment of B-lymphoid malignancies. This preclinical study investigated antitumor activity of CMC-544 against CD22+ acute lymphoblastic leukemia (ALL). CMC-544 inhibited in vitro growth of ALL cell lines more potently than that of Ramos B-lymphoma cells. When administered to nude mice with established sc xenografts of REH ALL, CMC-544 caused dose-dependent inhibition of xenograft growth producing complete tumor regression and cures in tumor-bearing mice at the highest dose of 160 microg/kg of conjugated calicheamicin. In contrast, a nonbinding control conjugate was 16-fold less effective than CMC-544 in inhibiting growth of REH ALL xenografts. When REH cells were injected intravenously in scid mice and allowed to disseminate systemically, mice developed hind-limb paralysis that was effectively prevented by treatment with CMC-544. Flow cytometric analysis of cells recovered from the bone marrow from mice with disseminated disease verified the presence of engrafted ALL cells. Significantly reduced numbers of ALL cells were recovered from the bone marrow of CMC-544-treated mice than from vehicle-treated mice with disseminated disease. The anti-leukemia activity of CMC-544 demonstrated here further supports clinical evaluation of CMC-544 for the treatment of CD22+ leukemia.