Genetic information is transformed from DNA to RNA and eventually to proteins. The protein phenotype is dependent mainly on the mRNA produced during transcription. Isoform switching is a series of events that occurs after DNA is successfully transcribed into pre-mRNA, which can generate different transcripts from the same gene, leading to both structurally and functionally different and usually pathogenic proteins. Although alternative splicing regulates normal cell stability, it also plays a crucial role in tumor cells under pathological conditions, affecting cancer progression, metastasis, and rapid proliferation by aberrant splicing. Alternative splicing events are linked to at least 15% of all cancers and other fatal diseases. However, reliable quantification of alternative splicing is still hampered by technological constraints, most notably the short read duration. During an RNA-seq experiment, mRNA is taken from tissue, fragmented, and reverse transcribed into cDNA, which is then amplified and sequenced using high-throughput, short-read sequencing techniques.This review provides insights into various alternative splicing events concerning the immune system, immune escape, and immune therapy and how these events can eventually lead to the development of fatal diseases such as cancer. This review may help identify key biomarkers for a disease's potential prognostic, diagnostic, and therapeutic activities.