We monitored his serum‐soluble interleukin‐2 receptor (sIL‐2R) levels, the number of tumour cells in the blood using flow cytometric analysis (small‐sized tumour cells; CD30‐5‐8+, large‐sized tumour cells; CD30+), and the expression levels of NPM‐ALK mRNA transcripts in the tumour cells by droplet digital polymerase chain reaction (ddPCR) over time as markers of treatment efficacy (Figure S1). This evidence concerns the gene ALK and neoplasm.