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ASCO GI 2026 Begins: 10 Studies and Results to Watch

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ASCO GI 2026 Begins: 10 Studies and Results to Watch
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10 Scientific Studies to Watch at ASCO GI 2026

A New Era in Oncology

Taking place in San Francisco on 8-10 January 2026, the ASCO Gastrointestinal Cancers Symposiumcould become a historic turning point that reshapes treatment paradigms, beyond announcing new drugs.

Longstanding questions such as "Is immunotherapy alone sufficient?", "Can we breach the KRAS fortress in pancreatic cancer?" and "Is chemotherapy-free treatment possible in gastric cancer?" will receive clear answers from Phase 3 results presented at the meeting.

The meeting brings together 5,100 oncology professionals. From 1037 scientific abstracts, we selected the 10 most critical studies likely to affect clinical practice, examining their designs, objectives and striking reported findings.

1. HERIZON-GEA-01: Changing Standards in Gastric Cancer

Title: First-Line Treatment in HER2-Positive Gastroesophageal Adenocarcinoma: Zanidatamab Combinations

Study Design
  • Type: Phase 3, randomized, global, open-label.
  • Patient Population: Previously untreated advanced/metastatic HER2-positive gastric or GEJ cancer.
  • Arms:
    1. Zanidatamab + Chemotherapy (CAPOX/FP)
    2. Zanidatamab + Chemotherapy + Tislelizumab (PD-1 Inhibitor)
    3. Control: Trastuzumab + Chemotherapy
Endpoints
  • Primary: Progression-Free Survival (PFS) and Overall Survival (OS).
  • Secondary: Objective Response Rate (ORR), Duration of Response (DoR), Safety.
Results
  • PFS: 12.4 months in the zanidatamab arms vs 8.1 months with trastuzumab (HR ~0.65).
  • OS: Median OS reached 26.4 months with the triple combination (control: 19.2 months).
  • Safety: Diarrhea (40%) was the most common side effect, but was manageable.

DROZDOGAN Commentary: Zanidatamab, with a structure binding HER2 at two different sites, is challenging trastuzumab's dominance. Survival beyond 2 years is a historic achievement in gastric cancer.

2. ILUSTRO: A New Gastric Cancer Target, "CLDN18.2"

Title: In CLDN18.2-Positive Gastric Cancer: Zolbetuximab Combinations

Study Design (Phase 2, Multicohort):

Patients with CLDN18.2-positive (over 75% staining), HER2-negative metastatic gastric cancer.
Cohort 2 (1st Line): Zolbetuximab + mFOLFOX6.

Results

In untreated patients, adding zolbetuximab significantly improved both tumor response rates (ORR) and time to progression (PFS). This provides strong evidence supporting the Phase 3 SPOTLIGHT and GLOW studies.

3. COMMIT (NRG-GI004): Single or Combination Therapy in MSI-H Colorectal Cancer?

Title: In MSI-H Metastatic Colorectal Cancer: Atezolizumab Monotherapy vs. Combination Therapy

Study Design (Phase 3, Randomized):
  • Patient Population: Previously untreated dMMR/MSI-H metastatic colorectal cancer.
  • Arm A: Atezolizumab (Single Agent).
  • Arm B: Atezolizumab + mFOLFOX6 + Bevacizumab (Combination).
  • Primary Endpoint: Progression-Free Survival (PFS).
Results
  • PFS Difference: In the combination arm, 30.0 months versus only 4.3 months. (HR: 0.44)
  • ORR: Response rates were 80.6% with the combination and 46% with monotherapy.

DROZDOGAN Commentary: This is a striking result. While pembrolizumab alone is highly effective (KEYNOTE-177), atezolizumab's poor monotherapy performance (4.3 months PFS), as a PD-L1 inhibitor, challenges chemotherapy-free treatment in this population or highlights differences between drugs (PD-1 vs PD-L1).

4. BREAKWATER: Reducing Chemotherapy in BRAF-Mutant Cancer

Title: In BRAF V600E-Mutant mCRC: First-Line Encorafenib + Cetuximab + Chemotherapy

Study Design (Phase 3):

In BRAF V600E-mutated disease, targeted drugs (Encorafenib + Cetuximab) combined with lighter chemotherapy (FOLFIRI) were compared with standard chemotherapy.

Results

The targeted combination produced a much higher response rate (64.4% vs 39.2%) and a survival advantage (OS HR: 0.49) over standard treatment. It establishes a new standard of care in BRAF-mutant disease, the most aggressive colorectal cancer subtype.

5. PT886-101: Dual-Target Hope in Pancreatic Cancer

Title: The Bispecific Antibody PT886 in Metastatic Pancreatic Cancer

  • Mechanism: PT886 binds simultaneously to tumor-cell Claudin 18.2and the immune-suppressing target CD47, acting as a bispecific antibody.
  • Design: Phase 1/2 dose escalation, combined with standard chemotherapy (Gem/Nab-Pac).
Results

Early findings show tolerability and tumor shrinkage even in chemotherapy-resistant pancreatic tumors. It could make pancreatic cancer, a cold tumor, more responsive to immunotherapy.

5 Other Critical Studies to Follow

Study Cancer Type Mechanism / Innovation Summary of Findings
6. ASP3082-001 Pancreatic and Solid Tumors KRAS G12D Degrader (A molecule that degrades the mutant protein). First-in-human study. Safe, with early antitumor activity.
7. TIGeR-PaC Locally Advanced Pancreatic Cancer (LAPC) Intra-Arterial Gemcitabine (RenovoTAMP). Delivery directly into the tumor's blood vessels. Fewer systemic side effects and higher intratumoral drug concentrations.
8. ALTAIR Colorectal Cancer (After Surgery) ctDNA Positive (MRD+) patients treated with Lonsurf (FTD/TPI). Substantial increase in disease-free survival (DFS): 9.23 months vs 5.55 months.
9. CHALLENGE-CRC Colorectal Cancer Survivors Structured Exercise Program. Regular exercise reduces cancer mortality risk.
10. DISCO-NET Neuroendocrine Tumors (NET) Next-generation PET Imaging Agents. Superior to existing methods, particularly for detecting liver metastases.
DROZDOGAN Academy Commentary: What Does the Future Hold?

ASCO GI 2026 signals the arrival of "Personalized Treatment 2.0" . We no longer simply say gastric cancer: specifying CLDN18.2-positive or HER2-positive gastric cancer allows precise treatment tailoring.

In particular, ALTAIR is critical because it demonstrates that postoperative blood ctDNA monitoring is ending blind chemotherapy and ushering in treatment only for patients who need it.

These advances may take time to reach patients in Turkey, but the scientific direction is clear: less toxicity, more targeted treatment and longer lives.

This report is based on the ASCO Gastrointestinal Cancers Symposium 2026 program and released abstracts.
Date: 8-10 January 2026 | Location: Moscone Center, San Francisco
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