(Esophageal/Gastric Cancer) ASCO-GI 2018: Second-Line Pembrolizumab Plus Margetuximab Shows Efficacy in HER2-Positive Advanced Gastric and GEJ Adenocarcinoma

• April 6, 2018
• Reading time: 1 minute

At the Gastrointestinal Cancers Symposium (ASCO-GI 2018) held in San Francisco, California, January 18–20, 2018, Dr. Daniel V.T. Catenacci of the University of Chicago Pritzker School of Medicine presented Phase 1b/2 clinical trial results (NCT02689284) evaluating pembrolizumab (Keytruda) plus the anti-HER2 antibody margetuximab as second-line therapy in patients with HER2-positive gastric or gastroesophageal junction (GEJ) adenocarcinoma previously treated with trastuzumab.

Trial Design

This trial evaluated second-line treatment in patients with HER2-positive gastric or GEJ adenocarcinoma who had received prior trastuzumab. The regimen consisted of a 21-day cycle with pembrolizumab 200 mg plus margetuximab at either 10 mg/kg or 15 mg/kg. The primary endpoint was response rate.

Two dosing cohorts were evaluated: 9 patients received 10 mg/kg, and the higher-dose 15 mg/kg cohort included 48 patients.

Efficacy Results

Of the 48 patients in the 15 mg/kg cohort, 38 were evaluable:

• Partial response (PR): 18.4% (N=7)
• Stable disease (SD): 28.9% (N=11)

Subgroup analysis of PR patients:

• North American patients (N=30): Response rate 8.3%
• Asian patients (N=18): Response rate 35.7%

By tumor location:

• Gastric cancer patients: 80%
• GEJ adenocarcinoma: 53%

Safety

Among all patients, one serious adverse event (AE) occurred. All other patients tolerated the combination of pembrolizumab plus margetuximab without that level of reaction, indicating a relatively high tolerability profile.

Conclusions

Based on these results, Dr. Daniel V.T. Catenacci concluded that second-line pembrolizumab plus margetuximab demonstrated meaningful antitumor activity and confirmed tolerability in HER2-positive advanced gastric and GEJ adenocarcinoma patients.

Source: Phase 1b/2 study of margetuximab (M) plus pembrolizumab (P) in advanced HER2+ gastroesophageal junction (GEJ) or gastric (G) adenocarcinoma (GEA). (ASCO-GI 2018, Abstract No. 140)

Tags: #GastricCancer #EsophagealCancer

• Clinical trial drug

Medical Supporter was formerly certified as an international medical visa guarantor by Japan's Ministry of Foreign Affairs and the Ministry of Economy, Trade and Industry (B-066).

Figure 1

Figure 2

Figure 3

Figure 4