ALLOGENEIC NK CELL THERAPY SHOWS PROMISE FOR NHL
Results of a Phase 1 Trial of Gda-201, Nicotinamide-Expanded Allogeneic Natural Killer (NK) Cells in Patients with Refractory Non-Hodgkin Lymphoma (NHL) and Multiple Myeloma
Veronika Bachanova, MD, PhD (University of Minnesota) discussed a trial of allogeneic NK cell therapy in patients with non-Hodgkin lymphoma and multiple myeloma. NK cells (GDA-201) were obtained from donors, expanded in vitro using nicotinamide and IL-15, and then infused into patients who had undergone lymphodepleting chemotherapy. Patients also received low-dose IL-2 and either rituximab (NHL) or elotuzumab (MM).
Thirty-five patients were treated in this trial, 19 of whom had non-Hodgkin lymphoma, in a dose-escalation/expansion format. Median dose was 14.3 x 107 cells/kg, and no dose-limiting toxicities were observed throughout the trial, including no report of neurotoxicity, cytokine release syndrome (CRS), or other serious adverse events. After a median follow up of 10 months, the overall response rate in patients with NHL was 74%, including 13/19 patients with a complete response. This led to a median duration of response of 10 months. Transferred NK cells were observed in peripheral blood for 7-10 days after infusion. Four patients were re-treated with GDA-201 without lymphodepleting chemotherapy, and the NK cells were still found to persist and likely helped deepen responses in these patients. This study indicates a potential new avenue for treatment of patients with refractory hematologic malignancies.
Read more about the role of NK cells in cancer in this recent article from the Journal for ImmunoTherapy of Cancer (JITC).
NANOPLASMID ENGINEERING MAY ENHANCE CAR T THERAPY FOR MULTIPLE MYELOMA
Phase 1/2 Study of the Safety and Response of P-BCMA-101 CAR-T Cells in Patients with Relapsed/Refractory (r/r) Multiple Myeloma (MM) (PRIME) with Novel Therapeutic Strategies
A phase 1/2 trial of autologous BCMA CAR T cells, P-BCMA-101, was presented by Caitlin L. Costello, MD (University of California-San Diego). Patients in this trial have relapsed/refractory multiple myeloma and have been treated previously with an IMiD and proteasome inhibitor. After apheresis to collect T cells, P-BCMA-101 is developed and then administered to patients following lymphodepletion. A novel manufacturing technique utilizing a nanoplasmid to engineer the T cells was also tested.
Fifty-five heavily pretreated patients have been treated to date. Patients received single infusions of P-BCMA-101 at escalating doses from 0.75-15x106 cells/kg. Subsequently, patients were divided into cohorts that received biweekly infusions and administration of rituximab or lenalidomide, which prevents anti-CAR T antibody production. To evaluate efficacy of nanoplasmid-engineered cells, separate cohorts received T cells manufactured using that process. Throughout the entire study, the safety profile was favorable, with 17% of patients experiencing CRS and one instance of potential neurotoxicity. The investigators attribute the relative safety of P-BCMA-101 to the high proportion of stem cell memory T cells, which results in a more gradual expansion of the cells in vivo. Indeed, peak concentrations of P-BCMA-101 were noted 2-3 weeks after infusion, relative to 3-7 days with some other products, and were found to persist up to 1.5 years. The ORR in all patients using the traditional manufacturing approach was between 40-75%, depending on the dose of CAR T cells. At the 0.75x106 cells/kg dose, patients treated with the nanoplasmid-engineered cells had higher response rates than those with the traditional approach, at 67% compared to 50%. The investigators are only moving forward with the nanoplasmid-engineered cells at this point as a result.
Learn about the Society for Immunotherapy of Cancer’s recommendations for treatment of multiple myeloma in a recently published clinical practice guideline.
TRISPECIFIC T CELL ENGAGER DEMONSTRATES PRECLINICAL EFFICACY
Preclinical Study of a Novel Tri-Specific Anti-CD3/CD19/CD20 T Cell-Engaging Antibody As a Potentially Better Treatment for NHL
Jie Zhang, PhD (Chimagen Biosciences) outlined a preclinical investigation of CMG1A46, a T cell engaging antibody that binds to CD3, CD20 and CD19. The investigators hypothesized that targeting both CD19 and CD20 would help bypass potential antigen loss as a means of therapy resistance and conducted murine and monkey studies to test efficacy and safety of the agent.
The EC50 of CMG1A46 was 0.3 pM. In vitro studies indicated that CMG1A46 was more cytotoxic toward CD19+/CD20+ tumor cells than a monotargeted therapy, but less effective when only one antigen was present on tumor cells. Mice engrafted with either CD19+/CD20+ or CD19+CD20- tumors responded to treatment with CMG1A46, and this therapy could be administered at doses of >6 times higher levels than other T cell engagers without an appreciable increase in toxicity. In cynomolgus monkeys, the serum half-life of CMG1A46 at 0.5 mg/kg was calculated at 130 hours. Thus, after an induction regimen, weekly dosing of CMG1A46 was sufficient to maintain serum concentration. B cells were depleted within 24 hours of the first administration and depletion was sustained for >28 days after the last dose. T cells transiently decreased, and cytokine levels were elevated for 4-8 hours after the first administration. Based on these preclinical studies, the investigators plan to initiate a phase 1 trial of the agent in the coming year.
CELL-FREE DNA TCR PROFILING MONITORS T CELL DYNAMICS
Profiling T-Cell Receptor Diversity and Dynamics during Lymphoma Immunotherapy Using Cell-Free DNA (cfDNA)
Navika D. Shukla, BS (Stanford University) described a novel method known as SABER (Sequence Affinity capture and analysis By Enumeration of cell-free Receptors) for monitoring cell-free DNA (cfDNA) with the primary goal of examining T cell receptor diversity and dynamics. The technique maps sequencing reads from fragmented cfDNA in order to assign V gene, CDR3, and V genes, after a de-duplication error correction.
When compared to traditional hybrid-capture or amplicon-based MiXCR techniques, SABER TCR analysis detected more TCR clonotypes than either method. In patients with diffuse large B-cell lymphoma, immune cell dynamics following CAR T therapy were analyzed. While the number of CAR T cells found in the blood did not correlate with response, the presence of cfDNA from CAR T cells did. Additionally, TCR repertoire analysis indicated that a more clonal TCR pool after CAR T treatment (evidenced by a higher Gini coefficient) indicated a higher likelihood of response to therapy. Thus, the total T cell dynamics may have a greater impact than just the CAR T cell dynamics in determining therapeutic efficacy, a hypothesis that merits future investigation.
SAFETY AND PRELIMINARY EFFICACY OF BMCA X CD3 BISPECIFIC REVEALED
REGN5458, a BCMA x CD3 Bispecific Monoclonal Antibody, Induces Deep and Durable Responses in Patients with Relapsed/Refractory Multiple Myeloma (RRMM)
A phase 1 trial of REGN5458 was presented by Deepu Medduri, MD (Icahn School of Medicine at Mount Sinai). The trial tested the BCMA x CD3 bispecific in patients with heavily pretreated multiple myeloma with the goal of determining safety and tolerability. A total of 49 patients have been treated on trial, all of whom were CD38-refractory.
Two dose-limiting toxicities were recorded on the trial: one instance of acute kidney injury and a case of elevated AST/ALT. Cytokine release syndrome (CRS) occurred in 39% of patients, and 84% of these patients experienced CRS of grade 1, while the rest were grade 2. Other notable toxicity rates included 12% grade 1-2 neurotoxicity and 47% of patients having an infection of any grade. Across the study, the overall response rate was 39%. Of those patients that were evaluable, 4/7 patients achieved MRD-negativity. The median duration of response was six months, with 74% of responders still on treatment. Quality-of-life analysis indicated improvement beginning at week 4 and continuing on through week 24. As a result of this study, a phase 2 trial is now recruiting.
HEAVY-CHAIN-ONLY BCMA CAR T THERAPY INVESTIGATED
Deep and Durable Remissions of Relapsed Multiple Myeloma on a First-in-Humans Clinical Trial of T Cells Expressing an Anti-B-Cell Maturation Antigen (BCMA) Chimeric Antigen Receptor (CAR) with a Fully-Human Heavy-Chain-Only Antigen Recognition Domain
A novel BCMA-targeted CAR T therapy was discussed by Lekha Mikkilineni, MD (National Cancer Institute). This cellular therapy employs a gamma-retrovirus-encoded, fully human, heavy-chain-only BCMA binding domain rather than a traditional scFv platform. The therapy, FHVH-BCMA-T, was used to treat 20 patients with heavily pretreated multiple myeloma.
The maximum feasible dose of FHVH-BCMA-T was determined to be 6x106 cells/kg, which will be tested in future additional cohorts. CAR+ cells in the blood peaked at a median of 12 days post-infusion. All but one treatment was followed by cytokine release syndrome, all of grade 3 or lower. Neurologic toxicities occurred in 38% of patients, mostly low-grade. The objective response rate across all evaluable patients was 90%, which included 7/8 patients with high-risk cytogenics and 6/8 with extramedullary disease, as well as patients with TP53 mutations and t(4;14) translocations. At the highest dose levels of 6 or 12x106 cells/kg, 7/8 patients have ongoing responses with a median duration of 20 weeks. Notably, upon relapse, 3/6 analyzed patients demonstrated BCMA negativity, indicating clonal selection, tumor immune evasion, or another concerning relapse mechanism. The investigators have future studies planned, given the responses seen in this initial trial.
CAR T THERAPY WITH TCR-MIMIC ANTIBODY DEMONSTRATES SPECIFICITY FOR HLA-PEPTIDE-POSITIVE CELLS
A TCR Mimic Antibody-Directed CAR T Cell Specific for Intracellular NDC80 Is Broadly Cancer Reactive and Displays High Activity Against Hematological Malignancies
Martin G. Klatt, MD (Memorial Sloan Kettering Cancer Center) described a novel CAR T therapy that employs a TCR mimic antibody as the antigen recognition domain. By identifying peptides that are presented by HLA-A*02:01 in tumor cells and not healthy tissues, the investigators identified an NDC80-derived peptide as a potential target for cell therapy.
NDC80 was associated with poor outcomes in many cancers, without any reported expression on healthy tissues, making it a good target for CAR T therapy. A phage library screening was employed to identify an antibody that recognized the HLA-peptide complex, which was then used to develop a CAR T therapy. In vitro tests verified the sensitivity of the NDC80-directed CAR T cells, wherein many antigen-positive cancer cell lines were successfully killed without activity toward healthy PBMCs or target-negative cells. The highest activity was noted against hematological malignancies, hypothesized to be the result of higher antigen expression. This technique not only showed efficacy for NDC80-positive cell killing, but also points to a method for targeting intracellular antigens through adoptive cell therapies.
CD5 KNOCK-OUT MAY BOOST EFFICACY OF CAR T THERAPY
CRISPR-Cas9 Knock out of CD5 Enhances the Anti-Tumor Activity of Chimeric Antigen Receptor T Cells
The differing roles of CD5 in malignant cells and T cells were exploited by Marco Ruella, MD (University of Pennsylvania) and colleagues to develop a CD5-knockout CAR T therapy. CD5 is a promising target on cancer cells as it is expressed by many hematologic malignancies; however, its expression by T cells inhibits their activation. A CAR T product was therefore designed that lacked intrinsic CD5 expression and targeted CD5; this CD5 knock out approach was applied to other CAR constructs as well.
First, a CD5-directed CAR T therapy was developed and modified through CRISPR-Cas9 deletion of CD5 expression by the T cells. CD5 KO CAR T cells contained a higher proportion of central T memory cells as well as lower expression of exhaustion/activation markers at the end of manufacturing, potentially indicating lessened fratricide. Murine studies with the CD5 KO and WT CAR T cells showed tumor control with both entities but enhanced CAR T expansion with the CD5 KO version, leading to longer overall survival for mice with leukemia treated with this construct. The impact of CD5 knockout was further investigated in CD19-targeted CAR T cells and once again showed improved efficacy and outcomes over WT cells. The investigators found that CD5 KO CAR T cells displayed higher phosphorylation of signaling proteins associated with T cell activation and survival compared to WT, indicating a potential mechanism for the benefit of CD5 KO. The group proposes initiating early-phase clinical trials of CD5 KO CAR T therapy based upon the findings of this study.
CAR-NK CELLS SHOW ACTIVITY AGAINST AML
Engineered Memory-like NK CARs Targeting a Neoepitope Derived from Intracellular NPM1c Exhibit Potent Activity and Specificity Against Acute Myeloid Leukemia
Han Dong, PhD (Dana-Farber Cancer Institute) presented a study of engineered natural killer (NK) cells for adoptive cellular therapy of acute myeloid leukemia. The CAR was developed to target an intracellular neoepitope of NPM1c presented by HLA-A2, which is found in around 30% of AMLs. Cytokine-induced memory-like NK cells were employed and engineered using an unconventional pseudotyped lentivirus.
Before using NK cells, the group tested CAR T cells targeting the same peptide-HLA complex. These studies indicated the specificity of the targeting scFv, but transient anti-tumor effects and notable toxicities. They hypothesized that NK cells would result in lower toxicity and less incidence of tumor resistance. The lentiviral approach used in this study demonstrated enhanced transduction efficiency over traditional methods. Additionally, engineering the NK cells to express either secreted or membrane-bound IL-15 led to engineered NK cells with higher survival and viability. These effects combined led to notable anti-tumor capabilities for cancer cells expressing the peptide-HLA-A2 complex without activity toward target-negative cells. This and future studies will certainly help optimize new cell therapies for the fight against aggressive hematologic malignancies.
You can read about current guidelines for the treatment of acute leukemia in the recently published SITC clinical practice guideline in JITC.
IN-DEPTH ANALYSIS OF AML MICROENVIRONMENT POINTS TOWARD FUTURE THERAPEUTIC INTERVENTIONS
Single-Cell Characterization of Acute Myeloid Leukemia (AML) and Its Microenvironment Identifies Signatures of Resistance to PD-1 Blockade Based Therapy
Hussein A. Abbas, MD, PhD (MD Anderson Cancer Center) and colleagues characterized AML tumor and microenvironment cells using single-cell RNA sequencing to analyze features associated with response and resistance to PD-1 therapy. They studied samples from AML patient aspirates as well as bone marrow samples from healthy donors.
Samples from AML tissues tended to cluster by individual patient, regardless of response or treatment. However, in an aggregate analysis, pre-treatment samples from patients who responded to nivolumab + azacitidine tended to have lower leukemia stemness scores, evidenced by LSC17, compared to patients without responses. In addition, inferred copy number loss of chromosome 7/7q was associated with resistance to this therapy and was further explored in a cohort of patients treated only with azacitidine. In these patients, no correlation was found between deletion of 7/7q and response, indicating that this alteration resulted in immunotherapy-specific resistance, hypothesized to be the result of interferon gamma-responsive genes in the vicinity of 7/7q. Comparison of healthy and AML cells indicated that T cells in the AML TME had lower diversity and more oligoclonal dominance; additionally, responders to PD-1 treatment demonstrated increased novel and expanded clones after treatment compared to non-responders. In-depth studies such as this will certainly lead to invaluable insights into the tumor microenvironment, leading the way to future therapeutic interventions.
A recent study in JITC investigated ways to overcome the heterogeneity of leukemia, such as was seen in this study.
IMPORTANCE OF NK CELLS IN CML INVESTIGATED
Single-Cell Roadmap of Immune Cell Response in Chronic Myeloid Leukemia
Immune responses to tyrosine kinase inhibitors (TKI) were analyzed by Jani Huuhtanen (University of Helsinki) and colleagues in order to determine the mechanisms for relapse and long-term treatment-free remission. Cells from 25 AML samples at various points in treatment were analyzed using single-cell RNA sequencing and TCR ab sequencing.
NK cells were found to be more abundant in CML patient samples compared to other malignancies, particularly including a more heterogeneous NK cell repertoire and an exhausted NK population expressing TIGIT and HAVCR2. Cessation of TKI therapy was found to upregulate NK cell exhaustion in all patients; however, patients with long treatment-free remission had fewer changes in their immune profiles than patients who quickly relapsed. Patients who relapsed >6 months after cessation of TKIs had pronounced regulatory T cell activity, hinting at a potential point for therapeutic intervention. Further analysis of CML cells found LGALS9, which interacts with many NK cell receptors including TIM-3, to be expressed on cancerous cells, and the tumor antigen PR1 also was expressed by CML cells with high BCR-ABL1 scores. T cell responses to PR1 varied between long-term remissions and early relapses as well. This detailed look at the CML immune environment may provide insight into future therapeutic interventions.