PEN-221

PEN-221 is a peptide-drug conjugate designed to selectively target somatostatin receptor 2 (SSTR2), which is overexpressed in various solid tumors, including neuroendocrine tumors (NETs) and small cell lung cancer (SCLC)[1][3][4]. The drug consists of a highly selective SSTR2-binding somatostatin analog linked via a cleavable disulfide linker to the cytotoxic payload DM1, a maytansinoid microtubule inhibitor[1][3][5]. Upon binding to SSTR2 on tumor cells, PEN-221 is internalized, leading to intracellular release of DM1, resulting in cell cycle arrest and apoptosis[5]. Preclinical studies demonstrated potent anti-tumor activity in SSTR2-expressing models. Clinical trials have evaluated its safety and efficacy primarily in patients with advanced NETs and SCLC[2][8].