Fig. 6: Efficacy of NARA1leukin against spontaneous metastasis.

(a) Experimental scheme. Mice were intradermally injected with 10⁶ LLC cells and treated with PBS, hIL-2/NARA1 complexes (1.5 µg/15 µg, three times weekly), or NARA1leukin (0.5 µg hIL-2 equivalent, twice weekly) from day 4 to 13. On day 14 the intradermal tumor was surgically removed, and mice were observed for 28 days. (b, c) Change in tumor volume in individual mice between day 4 and 14 (b) and tumor growth curves until day 14 (c) are shown. **p = 0.0018, *p = 0.0392. (d, e) Quantification of spontaneous lung nodules on day 28 (d), percentage distribution according to severity of metastasis categorized by nodule counts (e) are shown. ****p < 0.0001, *p = 0.0325. (f) Percentages of metastasis-free and metastasis-bearing mice at endpoint. (g) Experimental scheme. Mice were injected with 4T1 cells within mammary fat pad and treated as described in (a) until day 18. (h, i) Change in tumor volume in individual mice between day 7 and 28 (h) and tumor growth curves until day 28 (i) are shown. *p = 0.0338. (j, k) Quantification of spontaneous lung nodules on day 28 (j), percentage distribution according to severity of metastasis categorized by nodule counts (k) are shown. ****p < 0.0001, **p = 0.0079. (l) Percentage of metastasis-free and metastasis-bearing mice at endpoint. Data are presented as mean ± SD of three independent experiments (two for hIL-2/NARA1 group of 4T1), n = 12 (PBS), n = 11 (hIL-2/NARA1), n = 13 (NARA1leukin) (b–f), n = 13 (PBS), n = 7 (hIL-2/NARA1), n = 15 (NARA1leukin) (h–l) mice/group. Differences between groups at the same time point were analyzed using mixed effects analysis with Greenhouse-Geisser correction followed by Tukey’s multiple comparison test (c, i). Differences in nodule counts between groups were analyzed using Kruskal-Wallis test followed by Dunn’s multiple comparison test (d, j). ns, not significant. Source data are provided as a Source Data file.