Combination immunotherapy for kidney cancer — why two drug classes are started together

Combination immunotherapy means two medicines that work on different parts of the same problem are started together rather than one after the other. In advanced kidney cancer this takes two forms. In the first, two immune checkpoint drug classes are paired - a PD-1 inhibitor with a CTLA-4 inhibitor - so the immune response is released at two different points. In the second, a PD-1 inhibitor is paired with a VEGF-targeted tablet that acts on the blood supply the tumour builds for itself. Both are given as first treatment for disease that has spread, and both are set out in NCCN guidance. Which pairing is put forward depends on the pathology, the IMDC risk group, your other medical conditions and what you are able to tolerate.

Because the two agents do different jobs. A PD-1 inhibitor releases a brake that tumour cells use to switch off immune cells that have already found them. A CTLA-4 inhibitor acts earlier, where immune cells are first trained to recognise the cancer at all. A VEGF-targeted drug works on the tumour rather than the immune system, cutting back the new blood vessels it depends on, and in doing so it can make the tumour easier for immune cells to reach. Pairing two mechanisms is intended to give a better chance that the treatment does something, and to make the effect last longer. It also means two side-effect profiles at once, which is the trade-off your oncologist weighs with you.

Dual immunotherapy pairs two checkpoint drug classes, a PD-1 inhibitor and a CTLA-4 inhibitor. Both are given by infusion, usually as a short combined phase and then the PD-1 inhibitor alone. Everything it does is through your own immune system, so its side effects are immune-related and can appear weeks or months later. Immunotherapy with a targeted drug pairs a PD-1 inhibitor infusion with a daily VEGF-targeted tablet. The tablet acts on the tumour directly, so tumours often start shrinking sooner, but the tablet has its own day-to-day effects - blood pressure, sore hands and feet, mouth soreness, loose motions - and is taken continuously. Neither is a better option in the abstract. The choice is made case by case.

Checkpoint inhibitors work by removing a restraint on the immune system, so their side effects come from immune activity in normal organs. The thyroid, the skin, the bowel, the liver, the lungs and the pituitary and adrenal glands are the usual sites. Most are manageable when they are picked up early, which is why bloods are checked before each cycle and why new symptoms should be reported the same day rather than at the next visit. Treatment is often held and steroids started while things settle. When a VEGF-targeted tablet is part of the pairing, add raised blood pressure, hand and foot soreness, mouth ulcers, loose motions and fatigue. Side-effect management at CION is handled in-house by the medical oncology team.

Not routinely. In some other cancers PD-L1 staining on the tumour helps decide who is offered immunotherapy. In kidney cancer it has not proved reliable enough for that, and immune-based combinations are considered without it. What does guide the decision is the tumour type on your pathology report, whether sarcomatoid features are present, the IMDC risk group worked out from routine bloods and how long ago you were diagnosed, your kidney and liver function, your thyroid and heart status, and any autoimmune condition or long-term steroid or immunosuppressant use. If a PD-L1 result already appears on your report it is not wrong, and your oncologist will read it alongside everything else rather than treating it as the deciding factor.

There is no single answer, but the shape of a course is predictable. Where two checkpoint classes are paired, the combined phase is short - a few infusions given some weeks apart - and then the PD-1 inhibitor is continued on its own. Where a checkpoint drug is paired with a VEGF-targeted tablet, the infusions continue on a cycle and the tablet is taken daily. Treatment then carries on while it is working and while you are tolerating it, with scans at planned intervals to check. Many protocols set a maximum duration for the immunotherapy component, after which it stops even if things are going well. Pauses for side effects are common and do not mean the treatment has failed.