Tethered IL-15 augments antitumor activity and promotes a stem-cell memory subset in tumor-specific T cells.

Adoptive immunotherapy retargeting T cells to CD19 via a chimeric antigen receptor (CAR) is an investigational treatment capable of inducing complete tumor regression of B-cell malignancies when there is sustained survival of infused cells. T-memory stem cells (TSCM) retain superior potential for long-lived persistence, but challenges exist in manufacturing this T-cell subset because they are rare among circulating lymphocytes. We report a clinically relevant approach to generating CAR+ T cells with preserved TSCM potential using the Sleeping Beauty platform. Because IL-15 is fundamental to T-cell memory, we incorporated its costimulatory properties by coexpressing CAR with a membrane-bound chimeric IL-15 (mbIL15). The mbIL15-CAR T cells signaled through signal transducer and activator of transcription 5 to yield improved T-cell persistence independent of CAR signaling, without apparent autonomous growth or transformation, and achieved potent rejection of CD19+ leukemia. Long-lived T cells were CD45ROnegCCR7+CD95+, phenotypically most similar to TSCM, and possessed a memory-like transcriptional profile. Overall, these results demonstrate that CAR+ T cells can develop long-term persistence with a memory stem-cell phenotype sustained by signaling through mbIL15. This observation warrants evaluation in clinical trials.

Bispecific T-cells expressing polyclonal repertoire of endogenous γδ T-cell receptors and introduced CD19-specific chimeric antigen receptor.

Even though other γδ T-cell subsets exhibit antitumor activity, adoptive transfer of γδ Tcells is currently limited to one subset (expressing Vγ9Vδ2 T-cell receptor (TCR)) due to dependence on aminobisphosphonates as the only clinically appealing reagent for propagating γδ T cells. Therefore, we developed an approach to propagate polyclonal γδ T cells and rendered them bispecific through expression of a CD19-specific chimeric antigen receptor (CAR). Peripheral blood mononuclear cells (PBMC) were electroporated with Sleeping Beauty (SB) transposon and transposase to enforce expression of CAR in multiple γδ T-cell subsets. CAR(+)γδ T cells were expanded on CD19(+) artificial antigen-presenting cells (aAPC), which resulted in >10(9) CAR(+)γδ T cells from <10(6) total cells. Digital multiplex assay detected TCR mRNA coding for Vδ1, Vδ2, and Vδ3 with Vγ2, Vγ7, Vγ8, Vγ9, and Vγ10 alleles. Polyclonal CAR(+)γδ T cells were functional when TCRγδ and CAR were stimulated and displayed enhanced killing of CD19(+) tumor cell lines compared with CAR(neg)γδ T cells. CD19(+) leukemia xenografts in mice were reduced with CAR(+)γδ T cells compared with control mice. Since CAR, SB, and aAPC have been adapted for human application, clinical trials can now focus on the therapeutic potential of polyclonal γδ T cells.

Improving systemic therapy selection for inflammatory skin diseases: A clinical need survey.

Background: Empirical decisions to select therapies for psoriasis (PSO) and atopic dermatitis (AD) can lead to delays in disease control and increased health care costs. However, routine molecular testing for AD and PSO are lacking. Objective: To examine (1) how clinicians choose systemic therapies for patients with PSO and AD without molecular testing and (2) to determine how often the current approach leads to patients switching medications. Methods: A 20-question survey designed to assess clinician strategies for systemic treatment of AD and PSO was made available to attendees of a national dermatology conference in 2022. Results: Clinicians participating in the survey (265/414, 64% response rate) ranked "reported efficacy" as the most important factor governing treatment choice (P < .001). However, 62% (165/265) of clinicians estimated that 2 or more systemic medications were typically required to achieve efficacy. Over 90% (239/265) of respondents would or would likely find a molecular test to guide therapeutic selection useful. Limitations: To facilitate ease of recall, questions focused on systemic therapies as a whole and not individual therapies. Conclusion: Clinicians want a molecular test to help determine the most efficacious drug for individual patients.

Selection of a standard culture medium for primary culture of limulus polyphemus amebocytes.

This study provides information relevant to future research aimed at producing Limulus Amebocyte Lysate (LAL) in vitro, which would potentially reduce the need to harvest and bleed horseshoe crabs as in the current methods of LAL production. To address the need for primary culture of horseshoe crab amebocytes, this study tested the effects of a variety of standard insect cell culture media on amebocyte morphology and viability after 7 d of maintenance. Amebocyte morphology was least altered from in vivo form in Grace's Modified Insect Medium, with no observed degranulation of cells, as compared to the other media tested. There were significant differences in amebocyte viability among the six insect cell culture media tested. Grace's Modified Insect Medium sustained viability of 77.2 +/- 5.1% (mean +/- standard deviation) of amebocytes, followed distantly by Grace's Insect Medium with 35.1 +/- 8.7% amebocyte viability. Results indicate that Grace's Modified Insect Medium with horseshoe crab serum supplementation was the best candidate of the six media tested for future medium optimization for Limulus amebocyte requirements.

Tuning Sensitivity of CAR to EGFR Density Limits Recognition of Normal Tissue While Maintaining Potent Antitumor Activity.

Many tumors overexpress tumor-associated antigens relative to normal tissue, such as EGFR. This limits targeting by human T cells modified to express chimeric antigen receptors (CAR) due to potential for deleterious recognition of normal cells. We sought to generate CAR(+) T cells capable of distinguishing malignant from normal cells based on the disparate density of EGFR expression by generating two CARs from monoclonal antibodies that differ in affinity. T cells with low-affinity nimotuzumab-CAR selectively targeted cells overexpressing EGFR, but exhibited diminished effector function as the density of EGFR decreased. In contrast, the activation of T cells bearing high-affinity cetuximab-CAR was not affected by the density of EGFR. In summary, we describe the generation of CARs able to tune T-cell activity to the level of EGFR expression in which a CAR with reduced affinity enabled T cells to distinguish malignant from nonmalignant cells.

Sleeping Beauty Transposition of Chimeric Antigen Receptors Targeting Receptor Tyrosine Kinase-Like Orphan Receptor-1 (ROR1) into Diverse Memory T-Cell Populations.

T cells modified with chimeric antigen receptors (CARs) targeting CD19 demonstrated clinical activity against some B-cell malignancies. However, this is often accompanied by a loss of normal CD19+ B cells and humoral immunity. Receptor tyrosine kinase-like orphan receptor-1 (ROR1) is expressed on sub-populations of B-cell malignancies and solid tumors, but not by healthy B cells or normal post-partum tissues. Thus, adoptive transfer of T cells specific for ROR1 has potential to eliminate tumor cells and spare healthy tissues. To test this hypothesis, we developed CARs targeting ROR1 in order to generate T cells specific for malignant cells. Two Sleeping Beauty transposons were constructed with 2nd generation ROR1-specific CARs signaling through CD3ζ and either CD28 (designated ROR1RCD28) or CD137 (designated ROR1RCD137) and were introduced into T cells. We selected for T cells expressing CAR through co-culture with γ-irradiated activating and propagating cells (AaPC), which co-expressed ROR1 and co-stimulatory molecules. Numeric expansion over one month of co-culture on AaPC in presence of soluble interleukin (IL)-2 and IL-21 occurred and resulted in a diverse memory phenotype of CAR+ T cells as measured by non-enzymatic digital array (NanoString) and multi-panel flow cytometry. Such T cells produced interferon-γ and had specific cytotoxic activity against ROR1+ tumors. Moreover, such cells could eliminate ROR1+ tumor xenografts, especially T cells expressing ROR1RCD137. Clinical trials will investigate the ability of ROR1-specific CAR+ T cells to specifically eliminate tumor cells while maintaining normal B-cell repertoire.

Activating and propagating polyclonal gamma delta T cells with broad specificity for malignancies.

PURPOSE: To activate and propagate populations of γδ T cells expressing polyclonal repertoire of γ and δ T-cell receptor (TCR) chains for adoptive immunotherapy of cancer, which has yet to be achieved. EXPERIMENTAL DESIGN: Clinical-grade artificial antigen-presenting cells (aAPC) derived from K562 tumor cells were used as irradiated feeders to activate and expand human γδ T cells to clinical scale. These cells were tested for proliferation, TCR expression, memory phenotype, cytokine secretion, and tumor killing. RESULTS: γδ T-cell proliferation was dependent upon CD137L expression on aAPC and addition of exogenous IL2 and IL21. Propagated γδ T cells were polyclonal as they expressed TRDV1, TRDV2-2, TRDV3, TRDV5, TRDV7, and TRDV8 with TRGV2, TRGV3F, TRGV7, TRGV8, TRGV9*A1, TRGV10*A1, and TRGV11 TCR chains. IFNγ production by Vδ1, Vδ2, and Vδ1(neg)Vδ2(neg) subsets was inhibited by pan-TCRγδ antibody when added to cocultures of polyclonal γδ T cells and tumor cell lines. Polyclonal γδ T cells killed acute and chronic leukemia, colon, pancreatic, and ovarian cancer cell lines, but not healthy autologous or allogeneic normal B cells. Blocking antibodies demonstrated that polyclonal γδ T cells mediated tumor cell lysis through combination of DNAM1, NKG2D, and TCRγδ. The adoptive transfer of activated and propagated γδ T cells expressing polyclonal versus defined Vδ TCR chains imparted a hierarchy (polyclonal>Vδ1>Vδ1(neg)Vδ2(neg)>Vδ2) of survival of mice with ovarian cancer xenografts. CONCLUSIONS: Polyclonal γδ T cells can be activated and propagated with clinical-grade aAPCs and demonstrate broad antitumor activities, which will facilitate the implementation of γδ T-cell cancer immunotherapies in humans.

Membrane-bound IL-21 promotes sustained ex vivo proliferation of human natural killer cells.

NK cells have therapeutic potential for a wide variety of human malignancies. However, because NK cells expand poorly in vitro, have limited life spans in vivo, and represent a small fraction of peripheral white blood cells, obtaining sufficient cell numbers is the major obstacle for NK-cell immunotherapy. Genetically-engineered artificial antigen-presenting cells (aAPCs) expressing membrane-bound IL-15 (mbIL15) have been used to propagate clinical-grade NK cells for human trials of adoptive immunotherapy, but ex vivo proliferation has been limited by telomere shortening. We developed K562-based aAPCs with membrane-bound IL-21 (mbIL21) and assessed their ability to support human NK-cell proliferation. In contrast to mbIL15, mbIL21-expressing aAPCs promoted log-phase NK cell expansion without evidence of senescence for up to 6 weeks of culture. By day 21, parallel expansion of NK cells from 22 donors demonstrated a mean 47,967-fold expansion (median 31,747) when co-cultured with aAPCs expressing mbIL21 compared to 825-fold expansion (median 325) with mbIL15. Despite the significant increase in proliferation, mbIL21-expanded NK cells also showed a significant increase in telomere length compared to freshly obtained NK cells, suggesting a possible mechanism for their sustained proliferation. NK cells expanded with mbIL21 were similar in phenotype and cytotoxicity to those expanded with mbIL15, with retained donor KIR repertoires and high expression of NCRs, CD16, and NKG2D, but had superior cytokine secretion. The mbIL21-expanded NK cells showed increased transcription of the activating receptor CD160, but otherwise had remarkably similar mRNA expression profiles of the 96 genes assessed. mbIL21-expanded NK cells had significant cytotoxicity against all tumor cell lines tested, retained responsiveness to inhibitory KIR ligands, and demonstrated enhanced killing via antibody-dependent cell cytotoxicity. Thus, aAPCs expressing mbIL21 promote improved proliferation of human NK cells with longer telomeres and less senescence, supporting their clinical use in propagating NK cells for adoptive immunotherapy.