New studies elucidate mechanisms driving cancer immune responses and chemoresistance, including how regulatory T cells amplify pro-inflammatory Th17 cells via IL-2, metabolic rewiring by androgens in polycystic ovary syndrome, and serine synthesis impairment due to respiration defects in lung cancer. Additionally, CD40 agonist antibodies show promise despite systemic toxicity concerns. These findings advance precision oncology and immune modulation strategies.