Company: AZN
Filing Date: 2025-03-07
Form Type: 6-K
Source: 0001654954-25-002412
Chunk: 2

Company: ASTRAZENECA PLC
Filing Date: 2025-03-07
Form: 6-K
Chunk 2
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CR rate compared to neoadjuvant chemotherapy alone (19% versus 7%, odds ratio 3.08; p<0.00001). 4

Data will be presented at a forthcoming medical meeting and shared with global regulatory authorities.

#### Notes

#### Gastric and gastroesophageal junction cancers
Gastric (stomach) cancer is the fifth most common cancer worldwide and the fifth-highest leading cause of cancer mortality. 1 In many regions, its incidence has been increasing in patients younger than 50 years old, along with other gastrointestinal (GI) malignancies. 5 Nearly one million new patients were diagnosed with gastric cancer in 2022, with approximately 660,000 deaths reported globally. 1

GEJ cancer is a type of gastric cancer that arises from and spans the area where the oesophagus connects to the stomach. 6

Disease recurrence is common in patients with resectable gastric cancer despite undergoing surgery with curative intent and treatment with neoadjuvant/adjuvant chemotherapy. Approximately one in four patients with gastric cancer who undergo surgery develop recurrent disease within one year, and one in four patients do not survive beyond two years, reflecting high unmet medical need. 7-8 Additionally, the five-year survival rate remains poor, with less than half of patients alive at five years. 9

#### MATTERHORN
MATTERHORN is a randomised, double-blind, placebo-controlled, multi-centre, global Phase III trial evaluating Imfinzi as perioperative treatment for patients with resectable Stage II-IVA gastric and GEJ cancers. Perioperative therapy includes treatment before and after surgery, also known as neoadjuvant/adjuvant therapy. In the trial, 948 patients were randomised to receive a 1500mg fixed dose of Imfinzi plus FLOT chemotherapy or placebo plus FLOT chemotherapy every four weeks for two cycles prior to surgery. This was followed by Imfinzi or placebo every four weeks for up to 12 cycles after surgery (including two cycles of Imfinzi or placebo plus FLOT chemotherapy and 10 additional cycles of Imfinzi or placebo monotherapy).

In the MATTERHORN trial, the primary endpoint is EFS, defined as the time from randomisation until progression that precludes surgery or requires non-protocol therapy, local or distant recurrence or progression of disease, or death due to any cause as assessed by blinded independent central review (BICR) according to RECIST