Treating cancer inside the lungs has always been a challenge. Traditional immunotherapies—treatments that help the immune system attack cancer—can be powerful, but they often come with difficult side effects because they circulate throughout the whole body.
A new experimental therapy called KB707 is trying to change that by taking a surprisingly simple route: patients breathe it in.
What Is KB707?
KB707 is a new kind of gene‑based immunotherapy built from a harmless, non‑replicating version of the herpes simplex virus (HSV‑1). But instead of causing infection, it acts like a delivery vehicle. Once inhaled, it brings two immune‑boosting molecules, IL‑12 and IL‑2, directly into the lung tumors, where they can activate the body’s cancer‑fighting cells.
As the study explains, KB707 is “a replication‑defective herpes simplex virus type 1 (HSV‑1)-based vector engineered to deliver human interleukin (IL)-12 and IL-2” to the tumor environment .
How IL‑12 Helps Fight Cancer?
Think of IL‑12 as the “commander” of the immune system.
What it does:
Activates killer T cells and NK cells
These are the immune system’s main cancer‑destroying cells.
Helps T cells see tumors more clearly
IL‑12 increases signals that make tumors more visible to the immune system.
Boosts long‑term immune memory
This means the immune system can stay alert and prevent tumors from coming back.
Why it matters in cancer?
Tumors often create a “cold” environment—quiet, suppressed, and invisible to immune cells.
IL‑12 turns that environment hot, meaning full of immune activity.
How IL‑2 Helps Fight Cancer?
If IL‑12 is the commander, IL‑2 is the “growth booster”.
What it does:
Helps T cells multiply rapidly
More T cells = more soldiers to attack the tumor.
Strengthens T‑cell survival
IL‑2 keeps them alive longer inside the tumor.
Supports NK cells
These cells kill cancer without needing prior training.
Why it matters?
Cancer often exhausts or depletes T cells. IL‑2 brings them back to full strength.
Why Inhalation Matters?
Most cytokine‑based therapies (like IL‑2 or IL‑12) can’t be given in high doses through the bloodstream because they cause severe side effects. By inhaling KB707, the treatment stays mostly in the lungs—where the tumors are—while minimizing exposure to the rest of the body.
The study specifically aimed to see whether inhalation could “deliver efficacious dose to the lung while minimizing systemic exposure” .
What Did the Study Find?
This early‑phase clinical trial included 39 patients with advanced solid tumors affecting the lungs. Many had already gone through several rounds of treatment.
Here are the key takeaways:
1. The treatment was safe and well tolerated
• No severe (Grade 4 or 5) treatment‑related side effects were reported.
• Most side effects were mild or moderate and short‑lived.
• Even at the highest tested dose, the maximum tolerated dose was not reached.
The study notes that “the majority of treatment‑related adverse events have been mild to moderate in severity and transient” .
2. Early signs of effectiveness were encouraging
Among 11 patients with non‑small cell lung cancer (NSCLC) who could be evaluated:
• 27% had their tumors shrink (overall response rate).
• 73% had their disease stabilize or improve (disease control rate).
• Tumors inside the lungs responded particularly well, with a 36% response rate.
• Many patients were older and heavily pre‑treated, making these results even more notable.
What Happens Next?
Because the inhaled therapy showed both safety and early activity, the study is now expanding to test KB707 in combination with pembrolizumab (Keytruda), a widely used immunotherapy. Researchers hope the two treatments together may boost the immune response even further.
Why This Matters?
If future studies confirm these results, inhaled KB707 could represent:
• A new way to deliver immunotherapy directly to lung tumors
• A method that avoids the harsh side effects of systemic cytokine therapy
• A promising option for patients who have already tried multiple treatments
It’s still early days, but the idea of fighting cancer with a therapy you can inhale—one that activates the immune system right where it’s needed—could open a new chapter in lung cancer treatment.