Nanrilkefusp alfa (SOT101), an IL-15 receptor βγ superagonist, as a single agent or with anti-PD-1 in patients with advanced cancers

Abstract

Nanrilkefusp alfa (nanril; SOT101) is an interleukin (IL)-15 receptor βγ superagonist that stimulates natural killer (NK) and CD8⁺ T cells, thereby promoting an innate and adaptive anti-tumor inflammatory microenvironment in mouse tumor models either in monotherapy or combined with an anti-programmed cell death protein 1 (PD-1) antibody. In cynomolgus monkeys, a clinical schedule was identified, which translated into the design of a phase 1/1b clinical trial, AURELIO-03 (NCT04234113). In 51 patients with advanced/metastatic solid tumors, nanril increased the proportions of CD8⁺ T cells and NK cells in peripheral blood and tumors. It had a favorable safety profile when administered subcutaneously on days 1, 2, 8, and 9 of each 21-day cycle as monotherapy (0.25-15 μg/kg) or combined (1.5-12 μg/kg) with the anti-PD-1 pembrolizumab (200 mg). The most frequent treatment-emergent adverse events were pyrexia, injection site reactions, and chills. Furthermore, early clinical efficacy was observed, including in immune checkpoint blockade-resistant/refractory patients.

Keywords: SOT101; anti-tumor efficacy; nanril; nanrilkefusp alfa; pembrolizumab combination; solid tumors.

Graphical abstract

Figure 1

Nanril as monotherapy or combined with an anti-PD-1 antibody induces strong NK and CD8⁺ T cell-dependent anti-tumor efficacy and induces an inflammatory tumor microenvironment (A) 3×10⁴ TC-1 cells were implanted s.c. in C57BL/6 mice on day 0. TC-1 tumor-bearing mice were treated s.c. with nanril at 2 mg/kg once daily on days 4–7 and 10–13 post inoculation. Antibodies to deplete NK/CD8⁺/CD4⁺ T cells were administered intraperitoneally (i.p.) on days −7, −4, −2, 4, 11, and 18. Depletion of NK cells markedly accelerated TC-1 tumor growth (there were no tumor-free mice at day 7). (B) 3×10⁴ TC-1 cells were implanted s.c. in C57BL/6 mice on day 0. Mice were treated s.c. with nanril at 2 mg/kg once daily on days 25–28 and 32–35 (day 25 randomization ∼0.1 cm²). Antibodies to deplete NK/CD8⁺/CD4⁺ T cells were administered i.p. on days 21, 24, 26, and 33. (C) 1×10⁶ TRAMP-C2 cells were implanted s.c. in C57BL/6 mice on day 0. Mice were treated s.c. with nanril at 1 mg/kg once daily on days 36–39 and 50–53 (day 36 randomization ∼0.1 cm²) or with vehicle alone as a control. (D) Gene Ontology enrichment analysis of the differentially expressed genes in the tumors, spleens, and lymph nodes collected 5 days after the start of treatment with nanril was determined by NanoString nCounter analysis (n = 5, 2 independent experiments). (E) Fold change in the relative percentage of specific immune cell populations, as detected by flow cytometry, in the tumors, spleens, and lymph nodes collected 5 days after starting nanril treatment. Values in control untreated samples were set to 1, and the relative percentage for untreated tumors was set to 1 (samples spleen, lymph nodes, and tumors n = 3–5, 2 independent experiments). (F) TRAMP-C2-bearing mice were treated s.c. with nanril at 1 mg/kg once daily on days 4–7 and 18–21 either alone or combined with an anti-PD-1 antibody at 12.5 mg/kg i.p. on days 10, 13, and 16. Nanril combined with an anti-PD-1 antibody significantly delayed tumor development in cured mice after re-challenge with TRAMP-C2 tumor cells on day 106 post treatment (6–10 mice/group). (G) TRAMP-C2-tumor bearing mice were treated s.c. as in (F). Antibodies for depleting NK/CD8⁺/CD4⁺ T cells were administered on days −7, −4, −2, 4, 11, and 18. Data represent the mean ± SEM of n = 2–3 or one representative experiment (8–10 mice per group). ∗p < 0.05, ∗∗p < 0.01, ∗∗∗p < 0.001, and ∗∗∗∗p < 0.0001 (one-way ANOVA or unpaired Mann-Whitney test). DCs, dendritic cells; M-MDSCs, monocytic myeloid-derived suppressor cells; ns, not significant; PMN-MDSCs, polymorphonuclear myeloid-derived suppressor cells. See also Figures S1 and S2.

Figure 2

Nanril administered s.c. on days 1, 2, 8, and 9 was selected as the optimal clinical schedule based on cynomolgus monkey studies (A) s.c. administration of nanril for 4 consecutive days induced greater proliferation of NK and CD8⁺ T cells on day 5 compared with i.v. administration (infusion over 60 min). No CD4⁺ T cell or Treg proliferation was detected by flow cytometry of peripheral blood mononuclear cells from cynomolgus monkeys. (B) qPCR analysis of immune cells expressing CD3⁻- and CD8a-related genes from skin biopsies. The skin biopsy was collected at the injection site and at a distant site from 8 days after the last dose (group s.c. 4×/w at 15 μg/kg and i.v. 4×/w at 40 μg/kg) and 2 days after the last dose (group s.c. 2×/w at 15 μg/kg). Biopsies from untreated (NT) monkeys not related to the study were used as the control. (C) PK profiles of nanril upon s.c. and i.v. administration. Serum was collected at the indicated time points and analyzed by ELISA. (D) Four (days 1–4; 4×/w) or two (days 1, 2; 2×/w) s.c. doses of nanril at 15 μg/kg induced similar proliferation of NK and CD8⁺ T cells on day 5, exceeding that achieved by a single (day 1; 1×/w) s.c. administration. (E) Immune cell activation during 3 weeks of nanril administration (days 22, 23, 29, 30, 36, and 37). An additional s.c. dose of nanril at 15 μg/kg at days 36 and 37 did not further increase the proliferation of NK or CD8⁺ T cells, regardless of the previous nanril treatment. Arrows represent dosing schedule; colors correspond to the immune cells in the graph and the dosing. (F) s.c. administration of nanril at 40 μg/kg in 21-day cycles (days 1, 2, 8, and 9 + 1 week off-treatment) (red dosing schedule below graphs) induced greater proliferation of NK cells, but not CD8⁺ T cells, compared with two administrations every week (days 1, 2, 8, 9, 15, 16 etc.) (black dosing schedule below graphs) in a 10-week scheduling study in cynomolgus monkeys. The magnitude of cell proliferation did not differ when nanril was administered with a 1-week (red dosing schedule below graphs) or 2-week (black dosing schedule below graph) off-treatment period during the course of the study. Treatment days/schedule are represented by bars; line color corresponds to treatment schedule. (G) The proliferation of human and cynomolgus monkey NK and CD8⁺ T cells in vitro showed similar patterns (Ki67⁺) to that observed in vivo in cynomolgus monkeys, as determined by flow cytometry. Cell counts were determined by using the percentages of a population within CD45⁺ cells obtained by flow cytometry and the white blood cell count from hematologic analysis. All studies comprised a mean ± SEM of 2 animals per group. See also Figure S3; Table S1.

Figure 3

Anti-tumor efficacy of nanril in patients with advanced/metastatic solid tumors (A and B) Swimmer plots of time on treatment in the monotherapy part (A) and in the combination part (B). (C and D) Waterfall plots of the best percent change in tumor size from baseline in the monotherapy part (C) and in the combination part (D).

Figure 4

Example of responses observed with nanril as monotherapy or combined with pembrolizumab (A and B) Confirmed partial response after treatment with nanril as monotherapy and combined with pembrolizumab. A patient with skin squamous cell carcinoma, previously refractory to the immune checkpoint blocker cemiplimab (anti-PD-1), was treated with nanril at 6 μg/kg and achieved confirmed PR. After relapse, the patient crossed over to the combination part of the trial (nanril 1.5 μg/kg in combination with pembrolizumab) and again developed a confirmed and durable clinical benefit. (A) Clinical and radiological evolution over time. (B) Positron emission tomography/computed tomography (PET/CT) imaging at baseline and 1 year later. (C) Complete response observed in a patient with mesothelioma with nanril as combined with pembrolizumab. Baseline and on-treatment (week 6) MRI scans showing CR in a patient with mesothelioma. The arrow indicates the target lesion (perihepatic peritoneal nodule). See also Figure S7.

Figure 5

Nanril induces PD changes in line with its mode of action in peripheral blood and tumor tissue PD in peripheral blood during cycle 1 and in paired tumor tissues prior to and during therapy in patients treated with nanril as monotherapy (A‒C, G and H) or in combination with pembrolizumab (D‒F, I and J). (A, B D, and E) (A, D) The percentage of proliferating (Ki67⁺) and (B, E) absolute numbers of NK, NKT, CD8⁺ T cells, memory CD8⁺ T cells, CD4⁺ T cells, and Tregs were evaluated by flow cytometry using peripheral blood samples collected pre-dose and at 6 days (Ki67⁺) or 15 days (absolute count) after starting treatment. (C and F) Maximal fold change in peripheral blood IFN-γ concentrations from baseline. Boxplots show the lower quartile, median, and upper quartile; whiskers represent the minimum and maximum values. (G–J) (G and I) Immune cell infiltration and (H, J) Immunosign21 gene score evaluated using paired tumor biopsies for 16 patients in the monotherapy part and 10 patients in the combination part. Biopsies were collected before treatment and on-treatment (cycle 2 or in week 20) and subjected to immunohistochemistry and NanoString gene analysis. Patients were divided into two groups according to their clinical response. Group 1 includes patients with confirmed PR (labeled #) or SD. Group 2 includes patients with progressive disease (unconfirmed and confirmed). ∗p < 0.05, ∗∗p < 0.01, ∗∗∗p < 0.001, and ∗∗∗∗p < 0.0001 (Wilcoxon-Mann-Whitney test). ns, not significant; PR, partial response; SD, stable disease; PD, progressive disease. See also Figures S8, S9, and S10.