Can DNA damage response inhibitors overcome drug resistance in pancreatic cancer?
Pancreatic cancer is notoriously resistant to standard treatments. DNA damage response (DDR) inhibitors target a vulnerability in cancer cells with certain genetic mutations, such as BRCA1/2. However, using them alone often leads to resistance. Research now focuses on combining DDR inhibitors with other drugs to overcome this resistance and extend benefits to more patients.
What the research says
A 2024 review highlights that while DDR inhibitors have moved from research to clinical practice for pancreatic cancer, single-agent therapy faces major hurdles: a narrow group of patients who benefit, primary and acquired resistance, and dose-limiting toxicities 1. To address this, researchers are developing combination strategies, such as the PAD/PADtal triple regimen, dual-target inhibitors, and combinations with immunotherapy or KRAS inhibitors 1.
A 2026 study identified a new mechanism: the ATM-TGS1-BRCA1 axis. In pancreatic cancer, TGS1 is overexpressed and helps repair DNA damage, leading to therapy resistance. Blocking TGS1 made cancer cells more sensitive to DNA-damaging drugs and PARP inhibitors, suggesting a way to overcome resistance 9.
Another 2025 study found that combining a KRAS inhibitor (MRTX1133) with an FDA-approved drug (bedaquiline) disrupted the DNA helicase CMG complex, which is essential for DNA replication. This combination showed enhanced cell-killing effects in lab models, though it also triggered survival signals that need further targeting 10.
Additionally, a 2023 study showed that combining a CDK4/6 inhibitor with an ERK-MAPK inhibitor synergistically suppressed growth of KRAS-mutant pancreatic cancer cells, leading to a clinical trial 8. These findings collectively show that DDR inhibitors, when used in rational combinations, can overcome resistance mechanisms.
What to ask your doctor
- Could I benefit from DNA damage response inhibitors, such as PARP inhibitors, based on my tumor's genetic profile?
- Are there clinical trials testing combination therapies with DDR inhibitors for pancreatic cancer that I might be eligible for?
- How do doctors monitor for resistance when using DDR inhibitors, and what options exist if resistance develops?
- What are the potential side effects of DDR inhibitor combinations, and how are they managed?
- Is there a role for testing TGS1 or other DNA repair markers in my tumor to guide treatment?
This question is drawn from common patient questions about Oncology and answered using cited medical research. We do not provide individualized advice.