P1, N=3, Terminated, Institute of Hematology & Blood Diseases Hospital, China | N=18 --> 3 | Recruiting --> Terminated; It did not reach the expected results of clinical trial

P1, N=45, Not yet recruiting, Masonic Cancer Center, University of Minnesota | Initiation date: Oct 2024 --> Jan 2025

P1, N=45, Not yet recruiting, Masonic Cancer Center, University of Minnesota

This work demonstrates that CD33xIL15 fusion proteins are capable of targeting leukemic cells and stimulating local T cells in vitro and of concentrating in the tumour in AML xenografts. It also highlights the importance of 89Zr-immunoPET to guide the development and selection of tumour-targeted antibody-cytokine fusion proteins.

Showing for the first time that a membrane-proximal CAR is superior to a membrane-distal one in the setting of CD33 targeting, our results demonstrate the rationale for targeting membrane-proximal epitopes with high-affinity binders. We also demonstrate the importance of optimizing CAR T cells for functionality in settings of both low antigen density and clinically relevant patient-derived models.

CRS was mitigated with stepwise dosing of AMG 330, prophylactic dexamethasone, and early treatment with tocilizumab. Among 60 evaluable patients, eight achieved complete remission or morphologic leukemia-free state; of the 52 non-responders, 37% had ≥50% reduction in AML bone marrow blasts. AMG 330 is a promising CD33-targeted therapeutic strategy for R/R AML.

In addition to the anti-tumor effects of AMV564 on the clearance of MOLM13CG cells in vivo, similar effects were seen when primary CD33+ human AML cells were engrafted in NSG mice even when the human T cells made up only 2% of the peripheral blood cells and AML cells made up 98%. These studies suggest that AMV564 is a novel and effective bispecific diabody for the targeting of CD33+ AML that may provide long-term survival advantages in the clinic.

While previous CD33-targeting antibody-drug conjugates (ADCs) like gemtuzumab ozogamicin (GO, Mylotarg) have shown efficacy in AML treatment, they have suffered from toxicity and narrow therapeutic window...The development of GLK-33 addresses the limitations of previous ADCs, offering a wider therapeutic window, improved tolerability, and activity against drug-resistant leukemia cells. These findings encourage further exploration of GLK-33 in AML through clinical trials.

T-cell activation following treatment suggested target engagement but did not correlate with clinical activity. Safely reaching the projected exposure level for JNJ-67571244 efficacy was not achieved, thus MTD and RP2D were not determined.

Finally, in patient marrow specimens, CC-96191 eliminated AML cells but not normal monocytes, suggesting selectivity of TriNKET-induced cytotoxicity toward neoplastic cells. Together, these findings support the clinical exploration of CC-96191 as in NCT04789655.

P1, N=1, Terminated, Amgen | Phase classification: P1b --> P1

P1, N=18, Not yet recruiting, Imbioray (Hangzhou) Biomedicine Co., Ltd.

Taken together, these studies demonstrate that CD33 deleted hematopoietic compartment is protected from the CD33 directed immuno-therapy JNJ-67571244 both in in vitro cytotoxicity assays and preclinical xenotransplantation studies, with decreased concentrations of inflammatory cytokines associated with CRS. These findings enable the development of a next-generation AML treatment strategy by pairing trem-cel transplant with a subsequent CD33-directed bispecific compound to potentially improve safety and efficacy while minimizing myelotoxicity.

We propose a novel mechanism by which AMG 330-activated T cells prime and sensitize AML target cells in a forward feedback loop towards STING activation, leading to increased type-I-IFN production and induction of ISGs. The beneficial effect of physiological cGAMP in enhancing AMG 330-mediated cytotoxicity was accompanied by the pronounced expression of effector cytokines and an overall cytotoxic T-cell phenotype. We established a key role for interferon gamma in AMG 330-mediated cytotoxicity of AML cells and in rendering AML cells responsive to STING agonism.

CD33 is widely expressed by myeloid cells and is a validated drug target in acute myeloid leukemia (AML), as shown by the benefit of some patients from the CD33 antibody-drug conjugate gemtuzumab ozogamicin (GO)...In summary, our findings demonstrate that BMS-986357 TriNKET® has potent CD33-dependent cytolytic activity in vitro against human AML cells, supporting the drug's exploration in early phase clinical trials. One such trial (NCT04789655) has opened accrual for adults with relapsed/refractory AML.

CD33-M2T has demonstrated clear advantages over anti-CD33 monoclonal antibodies (e. g. , gemtuzumab, lintuzumab), including the ability to bind to the truncated alternatively spliced version of CD33, long duration of action, and no overt toxicities in mice. Conclusions These experiments demonstrate the preclinical potential of an innovative immunotherapy targeting CD33-positive childhood AML.

P1, N=102, Not yet recruiting, Institute of Hematology & Blood Diseases Hospital

T-cell fitness was assessed by T-cell function assays in co-cultures and immune synapse formation by applying a CD33 BiTE molecule (AMG 330). The addition of the immunomodulatory drug (IMiD) lenalidomide to co-cultures led to stabilization of immune synapses and improved subsequent T-cell responses. We conclude that target cells modulate CD33 BiTE molecule-dependent T-cell activation and hence, combinatorial strategies might contribute to enhanced efficacy.

P1, N=3, Terminated, Y-mAbs Therapeutics | N=36 --> 3 | Trial completion date: Sep 2024 --> Dec 2022 | Active, not recruiting --> Terminated | Trial primary completion date: Aug 2024 --> Dec 2022; Study terminated due to business priorities

In this study, we demonstrate CD33 ARC alpha targeted radiotherapy depletes human CD33 positive immune suppressing MDSCs present in multiple cancer types, to enhance antitumor immunity. These findings present a translatable strategy that supports further evaluation of 225Ac lintuzumab as a MDSC targeting agent to improve the efficacy of antitumor therapies.

P1, N=19, Recruiting, Zhejiang University

Immune cell therapy has become a cornerstone in cancer therapy. When administered in combination with daratumumab, QN-023a demonstrated superior ADCC compared to unmodified iPSC-derived NK cells against primary AML blasts from patients. Together, we have engineered iPSC-derived QN-023a NK cells as promising clinical drug candidates for treatment of AML.

In the initial study, the iNK cell backbone (iNK cells without the α3 MICA/B CAR) induced potent activity against the AML cell line HL60, and displayed further enhancement of activity with the addition of anti-CD33 TriKE (GTB-3650), representing combined effects of natural cytotoxicity and antibody-dependent cellular cytotoxicity. Studies with primary AML targets, +/- preincubation of decitabine and all-trans retinoic acid, known to upregulate NKG2D ligands in AML, are in progress and will be discussed. In summary, dual-targeting strategies using off-the-shelf CAR NK cells targeting α3 MICA/B in combination with antigen-specific TriKE targeting CD33 represent an ideal clinical strategy to enhance efficacy and durability of treatment in advanced AML.

P1, N=18, Recruiting, Institute of Hematology & Blood Diseases Hospital

We hypothesized that combining the CD33 BiTE construct AMG 330 with a cGAS-STING agonist has the potential to reverse immunosuppressive mechanisms and augment anti-leukemic activity...This leads to pronounced expression of effector cytokines and an overall cytotoxic T-cell phenotype, contributing to the beneficial effect of cGAMP in enhancing BiTE construct-mediated lysis. Ethics Approval Peripheral blood or bone marrow samples were collected from healthy donors and patients with acute myeloid leukemia at initial diagnosis, relapse, or complete remission after written informed consent was received in accordance with the Declaration of Helsinki and approval was granted by the Institutional Review Board of the Ludwig-Maximilian-Universität (Munich, Germany, reference number: 216-08).

P1, N=36, Terminated, AvenCell Europe GmbH | Trial completion date: Dec 2020 --> Jun 2022 | Unknown status --> Terminated | Trial primary completion date: Jul 2020 --> Jun 2022; The actions and measures to be taken to restart the trial could not be implemented which made the premature termination inevitability.

As proof of concept, a clinical trial of GTB-3550 (a CD33-targeted Tri-specific Killer Engager [TriKE] in AML) induced endogenous NK cell expansion and activation in refractory AML patients. Here we developed GTB-5550 (a B7H3 TriKE) as a novel dual camelid (cam) TriKE containing WT IL-15 and comprised of two cam engagers: targeting CD16 on NK cells and B7H3 on multiple solid tumors...Conclusions B7H3 TriKE delivers an NK cell specific IL-15 signal to expand NK cells and is highly specific against a broad array of cancers. Clinical manufacturing is underway with an IND planned to open clinical trials in 2023 in a number of solid tumors and multiple myeloma.

P1, N=68, Completed, Janssen Research & Development, LLC | Active, not recruiting --> Completed | Trial completion date: Oct 2022 --> Mar 2022

An I-labeled CD45 antibody (Iomab-B [apamistamab-I131]) is currently studied in the registration-type phase 3 SIERRA trial (NCT02665065) for this purpose...Clinical efforts with At-labeled CD45 antibodies and Ac-labeled CD33 antibodies (e.g. Ac-lintuzumab [Actimab-A]) are ongoing. A first anti-AML RIT may soon become available. This might propel further work to develop RIT-based treatments for AML, with many such efforts already ongoing.

ECM-targeted IL-2 combined with anti-CD33 immunotherapy represents an innovative approach associated with acceptable safety and encouraging biologic and clinical activity in posttransplant AML relapse. This trial was registered at EudraCT (2015-004763-37).

P1/2, N=12, Terminated, GT Biopharma, Inc. | N=60 --> 12 | Trial completion date: Aug 2025 --> Sep 2021 | Active, not recruiting --> Terminated | Trial primary completion date: Feb 2024 --> Aug 2021; Development of GTB-3550 halted due to development of the second generation camelid nanobody TriKE drug product, GTB-3650.

NK cell degranulation and IFN-gamma production of GTB-3550-treated samples were higher compared to that of control samples treated with B7H3 single domain or IL-15 alone. Ongoing experiments will evaluate functionality of GTB-5550 on FA patient samples as well as in spheroid assays. Taken together, this data shows that a GTB-5550 is able to drive NK cell activity against B7H3-expressing HNSCC cells, which presents potential for a B7H3-targeted TriKE to be used to be implemented clinically to treat HNSCC or FA-HNSCC patients.

AMV564 was active in vivo in a leukemia xenograft model when co-administered with healthy donor PBMC. Our findings provide a strong rationale for clinical investigation of AMV564 as both a single agent or in combination with anti-PD1 antibody, and in particular, for the treatment of cancers resistant to checkpoint inhibitors.

Using antibody single-chain variable region (scFv) sequences derived from amatuximab-recognizing MSLN, and from either blinatumomab or AMG330 targeting CD3, we engineered and expressed two MSLN/CD3-targeting BsAbs: MSLN-CD3 and MSLN-CD3, respectively. These data validate the in vivo efficacy and specificity of MSLN-targeting BsAbs. Because prior MSLN-directed therapies appeared safe in humans, MSLN-targeting BsAbs could be ideal immunotherapies for MSLN-positive pediatric AML patients.

P1, N=68, Active, not recruiting, Janssen Research & Development, LLC | Recruiting --> Active, not recruiting | N=180 --> 68

Currently, two CD33xCD3 BiTE ® antibody constructs (AMG 330 & AMG 673) are being investigated in phase I dose escalation trials in patients with relapsed/refractory Acute Myeloid Leukemia (AML) with early evidence of acceptable safety and anti-leukemic activity (Ravandi et al., ASH 2020; Subklewe et al., EHA 2020). They support the notion that T cell co-signaling receptors like CD86 and PD-L1 modulate T-cell response in an early event manner. Prospective analyses in clinical trials are needed to validate the relevance of checkpoint molecule expression on target cells as a potential predictive biomarker for response.

In this novel-novel combination dose-escalation phase 1 trial, we enrolled patients with AML relapse after allogeneic hematopoietic stem cell transplantation (HSCT) to evaluate the safety, pharmacokinetics, pharmacodynamics, and preliminary activity of F16IL2, an antibody-cytokine fusion protein composed of the human antibody fragment scFv(F16) in diabody format and two molecules of human IL-2, in combination with the Fc-optimized, ADCC-mediating anti-CD33 monoclonal antibody BI 836858. In the difficult-to-treat situation of posttransplant AML relapse, responses were observed at higher DL, even in patients with extramedullary disease. The antibody-mediated targeted delivery of IL-2 to the ECM combined with anti-CD33 immunotherapy represents an innovative experimental approach associated with acceptable safety and encouraging biologic and clinical activity in posttransplant AML relapse.

Jain, et al; Blood 2019; 134 (Supplement_1): 2885. doi: https://doi.org/10.1182/blood-2019-131041

Antibody single-chain variable region (scFv) sequences derived from amatuximab recognizing MSLN and from either blinatumomab or AMG330 targeting CD3 were used to engineer and express two MSLN/CD3-targeting BsAbs: MSLN AMA -CD3 L2K and MSLN AMA -CD3 AMG respectively...Chemotherapy (DA) consisted of 3 doses of 1.5 mg/kg daunorubicin iv and 5 doses of 50 mg/kg cytarabine ip...Conclusion These data validate the efficacy of MSLN-targeting BsAbs in PDX models with endogenous MSLN expression. Because prior MSLN-directed therapies appeared safe in humans, MSLN-targeting BsAbs could be ideal immunotherapies for MSLN-positive pediatric AML patients.

Additionally, T-cell function was assessed after stimulation with 1) CD3/CD28 beads; 2) AMG 330, a CD33/CD3 specific BiTE ® construct, after incubation with OCI-AML3 target cells; or 3) AMG 330 in an autologous ex vivo long-term culture system after incubation with primary AML cells (pAML)...These observations may highlight the significant role of the AML target cells in shaping a T-cell response. To this end, we will further analyze the longitudinal communication between T cells and their corresponding AML blasts.

P1/2, N=60, Active, not recruiting, GT Biopharma, Inc. | Recruiting --> Active, not recruiting

CD33 is a critical antigen for potential immunotherapeutic targeting in patients with AML. Based on this rigorous preclinical evaluation, our validated clinical grade lintuzumab-CD28/CD3ζ CD33CART immunotherapy is now under evaluation in a first-in-child/first-in-human phase 1 clinical trial for children and adolescents/young adults with relapsed/refractory AML.