Purpose: Chimeric antigen receptor (CAR) and T-cell receptor (TCR) T-cell therapies are effective in a subset of patients with solid tumors, but new approaches are needed to universally improve patient outcomes. Here, we developed a technology to leverage the cooperative effects of IL15 and IL21, two common cytokine-receptor gamma chain family members with distinct, pleiotropic effects on T cells and other lymphocytes, to enhance the efficacy of adoptive T cells. Experimental Design: We designed vectors that induce the constitutive expression of either membrane-tethered IL15, IL21, or IL15/IL21. We used clinically relevant preclinical models of transgenic CARs and TCRs against pediatric and adult solid tumors to determine the effect of the membrane-tethered cytokines on engineered T cells for human administration. Results: We found that self-delivery of these cytokines by CAR or TCR T cells prevents functional exhaustion by repeated stimulation and limits the emergence of dysfunctional natural killer (NK)-like T cells. Across different preclinical murine solid tumor models, we observed enhanced regression with each individual cytokine but the greatest antitumor efficacy when T cells were armored with both. Conclusions: The coexpression of membrane-tethered IL15 and IL21 represents a technology to enhance the resilience and function of engineered T cells against solid tumors and could be applicable to multiple therapy platforms and diseases. See related commentary by Ruffin et al., p. 1431

Despite good responses to first-line treatment with platinum-based combination chemotherapy, most ovarian cancer patients will relapse and eventually develop platinum-resistant disease with poor prognosis. Although reports suggest that integrin-linked kinase (ILK) is a potential target for ovarian cancer treatment, identification of ILK downstream effectors has not been fully explored. The purpose of this study was to investigate the molecular and biological effects of targeting ILK in cisplatin-resistant ovarian cancer. Western blot analysis showed that phosphorylation levels of ILK were higher in cisplatin-resistant compared with cisplatin-sensitive ovarian cancer cells. Further immunohistochemical analysis of ovarian cancer patient samples showed a significant increase in phosphorylated ILK levels in the tumor tissue when compared to normal ovarian epithelium. Targeting ILK by small-interfering RNA (siRNA) treatment reduced cisplatin-resistant cell growth and invasion ability, and increased apoptosis. Differential gene expression analysis by RNA sequencing (RNA-Seq) upon ILK-siRNA transfection followed by Ingenuity Pathway Analysis (IPA) and survival analysis using the Kaplan–Meier plotter database identified multiple target genes involved in cell growth, apoptosis, invasion, and metastasis, including several non-coding RNAs. Taken together, results from this study support ILK as an attractive target for ovarian cancer and provide potential ILK downstream effectors with prognostic and therapeutic value.

Neuroblastoma is a highly aggressive childhood solid tumor with poor outcomes. Chimeric antigen receptor (CAR) T cells have shown limited efficacy in neuroblastoma, with the best outcomes reported in patients with a low tumor burden, highlighting the need for further CAR optimization. One approach to addressing the high tumor burden involves engineering CAR T cells to release or express transgenic cytokines. However, its systemic toxicity remains an important therapeutic challenge. In this study, we evaluated the efficacy of IL15- and IL21-enhanced glypican 2 (GPC2)–targeted CAR T cells (GPC2-CAR T cells) in targeting high-burden neuroblastoma. Three strategies for expressing the cytokines were evaluated: constitutive secretion (GPC2-CAR + sol.IL15.IL21), constitutive membrane-tethered expression (GPC2-CAR + teth.IL15.IL21), and NFAT-inducible membrane-tethered expression (GPC2-CAR + NFAT.IL15.IL21). Engineered GPC2-CAR T cells were tested in vitro and in vivo using high neuroblastoma burden xenograft models. Additionally, single-cell RNA sequencing was used to profile the effector cells in the tumor microenvironment. All three versions of GPC2-CAR T cells significantly enhanced killing against a high neuroblastoma burden, both in vitro and in vivo, relative to control GPC2-CAR T cells. Mice treated with GPC2-CAR + NFAT.IL15.IL21 exhibited significantly lower anorexia-associated morbidity/mortality. Supporting these data, tumor-infiltrating GPC2-CAR + NFAT.IL15.IL21 developed an immunosuppressive transcriptional profile upon tumor regression, leading to prolonged survival in treated mice. In contrast, GPC2-CAR + teth.IL15.IL21 maintained a proinflammatory transcriptional signature despite near tumor clearance, resulting in hypercytokinemia and death. NFAT-inducible co-expression of tethered IL15/IL21 enhanced GPC2-CAR T-cell function against a high neuroblastoma burden with acceptable tolerability in mice. Further studies are required to validate these findings.

Radiopharmaceutical therapy (RPT) is a promising approach to treating solid tumors, but therapeutic advances are impeded by the lack of broadly expressed targets and shared molecular vulnerability across different tumor types. Here, we evaluate VLA-4 (integrin α4β1) as a potential target for RPT in solid tumors and use radiolabeled copper-64 ([64Cu]Cu-) and copper-67 ([67Cu]Cu-CB-TE1A1P-PEG4-LLP2A) LLP2A, a peptidomimetic ligand of VLA-4, for preclinical imaging and RPT testing. Expression of ITGA4, the gene encoding the alpha 4 subunit (CD49d) of VLA-4, was evaluated in a variety of cancer tissues from publicly available datasets. VLA-4 protein expression was determined by flow cytometry in 22 different human and murine cancer cell lines. We used orthotopic syngeneic (i.e., B16-F10, B78, 4T1, GL261, TH-MYCN, and E2A-PBX1) and human (i.e., SK-MEL-37, 143B, and IMR-5) cancer models for in vivo PET/CT imaging and biodistribution studies. Selected models were used for dosimetry calculations with [64Cu]Cu-LLP2A. To assess in vivo tolerability and efficacy, we performed studies of [67Cu]Cu-LLP2A in tumor-free and B16-F10–bearing C57BL/6J mice (activity range, 0–74 MBq [0–2 mCi]), respectively. We found ITGA4 is overexpressed in hematological malignancies and a variety of solid tumors compared with healthy tissue. VLA-4 was expressed at medium to high levels in 17/22 (77%), at low levels in 4/22 (18%), and negative in 1/22 (5%) tested cell lines. PET/CT imaging with [64Cu]Cu-LLP2A showed tracer uptake in tumors and on-target off-tumor uptake in lymphoid tissues. [67Cu]Cu-LLP2A administered at an activity range of 37 to 74 MBq (1–2 mCi) was tolerated and did not cause long-term hematological or tissue toxicity, except for thymic atrophy. We observed tumor dose response to the activity administered to mice with B16-F10 melanoma. In summary, VLA-4 is broadly expressed across a variety of different cancer tissues and preclinical cancer cell lines, making it a promising target for [67Cu]Cu-LLP2A RPT. With proven on-target on-tumor effect, acceptable toxicity profile, and favorable dosimetry in preclinical models, further investigation of [67Cu]Cu-LLP2A as an RPT agent is warranted.

Species of the genus Simarouba have been studied because of their antimalarial and antileukemic activities. A group of oxygenated terpenes called quassinoids have been isolated from species of the Simarouba genus, and are responsible for its therapeutic properties. We hypothesized that Simarouba tulae, an endemic plant from Puerto Rico, is a natural source rich in quassinoid compounds with anticancer activity. The leaves were processed and extracted with solvents of different polarities. The extracts were screened for their antiproliferative activity, and it was shown that the chloroform extract was the most active extract. This extract was purified using different chromatographic techniques to afford the quassinoid simalikalactone D (SKD). This compound was further characterized using NMR and X-ray diffraction analysis. A reassessment of original structural assignments for SKD is proposed. SKD showed high cytotoxicity activity, with an IC₅₀ of 55, 58, and 65 nM in A2780CP20 (ovarian), MDA-MB-435 (breast), and MDA-MB-231 (breast) cell lines, respectively. Exposure to SKD led to 15% inhibition of the migration of MDA-MB-231 cells.

Body weights from mice with orthotopic neuroblastoma that were treated with adoptive T-cells.