While ESMO 2023 is just about to begin, Amgen is all geared up to showcase its findings from the interim analysis of a Phase I study evaluating Amgen's bispecific antibody, AMG 509 in metastatic castration-resistant prostate cancer. Prostate cancer is the most common cancer in males affecting a large segment of the population in the US, with ~3,692,300 prevalent cases in 2022. 

Early-Stage Results for AMG 509 (xaluritamig) Illustrate Expanding Potential of Amgen's T-Cell Engagers in mCRPC

• Abstract Number – 1765O
• Abstract Type - Proffered Paper Session
• Indication – Metastatic Castration-resistant Prostate Cancer
• Technology - Bispecific Immune therapy

Interim results from a Phase I study of AMG 509 (xaluritamig), a novel bispecific STEAP1 x CD3 XmAb 2+1 bispecific antibody, demonstrates positive benefit/risk profile with robust anti-tumor activity in heavily pretreated patients with mCRPC. 

Bispecific antibodies are next generation monoclonal antibodies (mAbs). Bispecific antibodies recognize two antigens and have the potential to simultaneously inhibit different proteins, this inhibition process plays a very vital role in cancer progression.

Six-transmembrane epithelial antigen of prostate 1 (STEAP1) is highly expressed in prostate cancers, representing an attractive target for treating mCRPC. AMG 509 is a bispecific XmAb 2+1 T-cell engager that simultaneously binds to STEAP1 on tumor cells and the CD3 complex on T cells resulting in T-cell mediated lysis of STEAP1-expressing cells. The drug demonstrated significant antitumor activity in preclinical prostate cancer models.

Amgen is all set to present interim results from the Phase I study of AMG 509 in heavily pretreated patients with mCRPC in the upcoming ESMO conference. As per the Amgen’s recent update, a total of 67 RECIST-evaluable patients showed promising preliminary efficacy, with 16 (24%) having confirmed partial responses (PR) and 32 (48%) having stable disease (SD). At higher dosing levels (n=37), 15 patients (41%) achieved confirmed PR, and 14 (38%) had SD. The most frequent treatment-related adverse events included cytokine release syndrome (CRS; 72%, mostly low grade), fatigue (45%), myalgia (34%), and pyrexia (32%).

Apart from Amgen, other key players such as Xencor, Merus, Regeneron, and LAVA Therapeutics are also evaluating their bispecific antibody candidates for the treatment of mCRPC. However, these products are not the direct competitors to Amgen’s AMG 509, but have the potential to significantly impact the therapeutic space of prostate cancer.

Table represents the competitive landscape of bispecific antibodies in prostate cancer treatment