The purpose of this study is to find the highest dose of the investigational drug CA-4948 that can be given safely and to evaluate its preliminary anticancer effectiveness in patients with non-Hodgkin lymphoma that has come back or continued to grow despite prior therapy. CA-4948 works by blocking a protein in normal and cancerous B cells (a type of immune cell) called IRAK4, which may promote the growth and survival of B cells in lymphoma. CA-4948 is designed to fight cancer by blocking IRAK4, thereby stopping or reducing the signals that promote lymphoma B-cell survival.