Fig. 1: SPHK1 expression inversely correlates with survival after ICI therapy.

a SPHK1 expression in human nevi (n = 17) compared to primary (P) melanoma (n = 45), and in primary melanoma (n = 25) compared to metastatic (M) melanoma (n = 44) based on the Oncomine database. Data were compared using Mann–Whitney test. The bottom-most and topmost horizontal lines, the lower and upper hinges, and the middle line of the boxplots indicate the minimum and maximum values, the 25th and 75th percentiles, and the median, respectively. b Percentages of cancer cells positive for SPHK1 mRNA staining in metastatic melanoma tissues of 32 patients prior anti-PD-1 treatment (Low: ≤ 50% of tumor cells are positive (black points); High: > 50% of tumor cells are negative (red points)). c Representative mRNA staining of low and high SPHK1 expression. Skin (P1,P3) or lymph node (P2,P4) biopsies from patients (P). Percentages (%) indicate the proportion of cancer cells positive for SPHK1 mRNA staining. Large and small blue lines represent 200 and 20 μm, respectively. d Progression-free survival and e overall survival curves of patients with >50% of melanoma cells positive for SPHK1 (red line; n = 11) or <50% (black line; n = 21). Survival times were calculated from the first day of the cycle of anti-PD-1 post biopsy. Statistical significance was determined by log-rank test.