Chugai Files for Additional Indication of Tecentriq for Adjuvant Treatment of MSI-High Colon Cancer

• If approved, Tecentriq would become the first immune checkpoint inhibitor in Japan for adjuvant treatment of colon cancer
• Filing for an additional indication based on results from the investigator-initiated global Phase III ATOMIC trial

TOKYO, August 14, 2026 -- Chugai Pharmaceutical Co., Ltd. (TOKYO: 4519) today announced that it has filed a regulatory application with the Ministry of Health, Labour and Welfare for the anti-cancer agent/humanized anti-PD-L1 monoclonal antibody Tecentriq^® Intravenous Infusion 840mg [generic name: atezolizumab (genetical recombination)] for an additional indication as adjuvant treatment for adults and pediatric patients with microsatellite instability-high (MSI-High) colon cancer.

“Colorectal cancer is the most commonly diagnosed cancer in Japan, and recurrence after adjuvant chemotherapy remains a significant challenge in patients with pathological Stage III disease. In the ATOMIC trial, the addition of Tecentriq to standard adjuvant chemotherapy demonstrated a reduction in the risk of disease recurrence or death. We will continue our efforts toward obtaining approval so that Tecentriq can be delivered to patients with MSI-High colon cancer as a new standard of care,” said Chugai’s President and CEO, Dr. Osamu Okuda.

This filing is based on the results from the investigator-initiated global Phase III ATOMIC trial (Alliance A021502) in patients with pathological Stage III deficient mismatch repair (dMMR) colon cancer following curative resection^1,2. The trial evaluated the efficacy and safety of adding Tecentriq to standard adjuvant mFOLFOX6 chemotherapy. dMMR is known to lead to MSI-High status in tumor cells.
For the primary endpoint of disease-free survival (DFS), three-year DFS rates were 86.3% (95% CI: 81.8-89.8) in the Tecentriq combination arm and 76.2% (95% CI: 70.9-80.6) in the mFOLFOX6 arm.
The Tecentriq combination arm demonstrated a statistically significant improvement compared with mFOLFOX6 alone, reducing the risk of disease recurrence or death (stratified hazard ratio: 0.50, 95% CI: 0.35-0.73; p<0.001). The most common adverse events were hepatic dysfunction (43.9%), skin disorders (33.8%), and hypothyroidism (18.8%). The safety profile was consistent with the known safety profile of Tecentriq, and no new safety signals were identified.

Chugai Pharmaceutical, a leading company in the oncology field, remains committed to addressing unmet medical needs in cancer treatment with innovative medicines for patients and healthcare professionals.

About the ATOMIC (NCT02912559/Alliance A021502) trial^1,2
ATOMIC is an investigator-initiated overseas Phase III trial being conducted by the Alliance for Clinical Trials in Oncology, a research group supported by the U.S. National Cancer Institute (NCI), in patients with pathological Stage III deficient mismatch repair (dMMR) colon cancer following curative resection. The trial is being conducted as an open-label, randomized trial evaluating the efficacy and safety of a standard adjuvant mFOLFOX6 treatment arm (administered for six months) and a combination treatment arm in which mFOLFOX6 plus Tecentriq is administered for six months, followed by Tecentriq monotherapy for an additional six months (12 months in total). The FDA has granted Priority Review and is expected to make a decision on the approval by 9 October 2026.

About Colorectal Cancer with Deficient Mismatch Repair (dMMR) or Microsatellite Instability-High (MSI-High)
Colorectal cancer is the most commonly diagnosed cancer in Japan, with approximately 154,000 new cases reported in 2023 (approximately 102,000 cases of colon cancer and 52,000 cases of rectal cancer) and approximately 54,000 deaths reported in 2024 (approximately 38,000 cases of colon cancer and 16,000 cases of rectal cancer)³. Among colorectal cancer cases in Japan, approximately 6-7% are reported to have deficient mismatch repair (dMMR)^4,5. dMMR refers to a condition in which the DNA mismatch repair system is impaired, resulting in the development of microsatellite instability-high (MSI-High) tumors. Most tumors with dMMR exhibit MSI-High status. Because these tumors accumulate large numbers of somatic mutations and are therefore highly immunogenic, they are considered likely to respond to treatment with immune checkpoint inhibitors^6,7. However, clinical evidence supporting the use of immune checkpoint inhibitors in the adjuvant treatment of colorectal cancer has been limited to date.
Adjuvant chemotherapy is recommended for patients with pathological Stage III colorectal cancer; however, recurrence is still observed in approximately 30% of patients following treatment^8,9. Furthermore, prognosis remains poor once recurrent colorectal cancer progresses to an unresectable stage. Therefore, there remains a need for new adjuvant treatment options that can help reduce the risk of recurrence following curative resection.

About Tecentriq¹⁰
Tecentriq is an immune checkpoint inhibitor designed to target PD-L1 (programmed death-ligand 1) expressed on tumor cells or tumor-infiltrating immune cells. PD-L1 binds to PD-1 and B7.1 receptors on T cells and suppresses T-cell function. By inhibiting this interaction, Tecentriq is considered to restore T-cell activity and promote immune response against tumor cells. In Japan, Tecentriq was launched in April 2018 and has obtained approval for 7 tumor types (extensive-stage small cell lung cancer, non-small cell lung cancer, breast cancer, hepatocellular carcinoma, alveolar soft part sarcoma, extranodal natural killer/T-cell lymphoma nasal type, and thymic carcinoma).

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Sources:

1. ClinicalTrials.gov. Combination Chemotherapy With or Without Atezolizumab in Treating Patients With Stage III Colon Cancer and Deficient DNA Mismatch Repair [Internet; cited August 2026] Available from: https://clinicaltrials.gov/study/NCT02912559
2. Sinicrope FA, Ou FS, Arnold D, Peters WR, Behrens RJ, Lieu CH, Matin K, Cohen DJ, Potter SL, Nixon AB, Kottschade LA, Kathol E, Frankel WL, Shergill A, Hsu D, Reinacher-Schick A, Mehan P, Gold PJ, Khalil MF, Zemla T, Gatten C, O’Reilly EM, Meyerhardt JA. Atezolizumab plus FOLFOX for Stage III Mismatch Repair-Deficient Colon Cancer. N Engl J Med. 2026 Mar 26;394(12):1155-1166. doi: 10.1056/NEJMoa2507874. [Internet; cited August 2026] Available from: https://pubmed.ncbi.nlm.nih.gov/41880612/
3. Cancer Information Service, National Cancer Center, Japan. [Internet; cited August 2026] Available from: https://ganjoho.jp/reg_stat/statistics/stat/cancer/67_colorectal.html (Japanese only)
4. Shin-ichi A, Yoshiko A, Yoji N, et al.: Microsatellite instability-low colorectal cancer acquires a KRAS mutation during the progression from Dukes’ A to Dukes’ B. Carcinogenesis 2009; 30: 494-499 [Internet; cited August 2026] Available from: https://pubmed.ncbi.nlm.nih.gov/19147861/
5. Tsutomu I, Yoji N, Kensei Y, et al.: The clinical features of rectal cancers with high-frequency microsatellite instability (MSI-H) in Japanese males. Cancer Lett. 2004; 216: 55-62 [Internet; cited August 2026] Available from: https://pubmed.ncbi.nlm.nih.gov/15500949/
6. Japanese Society for Cancer of the Colon and Rectum. JSCCR Guidelines for the Treatment of Colorectal Cancer 2024 [Internet; cited August 2026] Available from: https://link.springer.com/article/10.1007/s10147-025-02899-8 (Summary in English)
7. Japan Society of Clinical Oncology. Clinical Practice Guideline for Genomic Medicine: dMMR Solid Tumors [Internet; cited August 2026] Available from: http://www.jsco-cpg.jp/precision-medicine/guideline/ (Japanese only)
8. Romain C, Julien T, Jack F, et al.: Microsatellite Instability in Patients With Stage III Colon Cancer Receiving Fluoropyrimidine With or Without Oxaliplatin.: An ACCENT Pooled Analysis of 12 Adjuvant Trials. J Clin Oncol. 2021; 39: 642-651 [Internet; cited August 2026] Available from: https://pubmed.ncbi.nlm.nih.gov/33356421/
9. Axel G, Alberto FS, Anthony FS, et al.: Duration of Adjuvant Chemotherapy for Stage III Colon Cancer. N Engl J Med 2018; 378: 1177-1188 [Internet; cited August 2026] Available from: https://pubmed.ncbi.nlm.nih.gov/29590544/
10. Tecentriq Intravenous Infusion 840mg / 1200mg. Electronic Package Insert Information (Revised December 2025, 12th Edition)