– SI-2 hydrochloride (EPH 116 hydrochloride) is a highly promising SRC-3 SMI: SRC-3 inhibitor (PPI), with IC50 values of 3-20 nM for breast cancer cell death. SI-2 hydrochloride (EPH 116 hydrochloride) has a much improved toxicity and pharmacokinetic profile, with acceptable oral availability[1].