p-fluorobenzonitrile, also known as 4-fluorobenzonitrile, is a pharmaceutical intermediate that can be used in the preparation of afatinib. Afatinib maleate was approved in the United States in 2013 for the treatment of metastatic non-small cell lung cancer (NSCLC) with epidermal growth factor receptor (EGFR) exon 19 deletion or exon 21 (L858R) replacement mutation.