A groundbreaking vaccine, known as iVAC (intratumoural vaccination chimera), holds significant promise for boosting survival rates in individuals afflicted with hard-to-treat cancers. This innovative, one-off jab is administered directly into tumours, operating through a dual mechanism that re-engineers cancer cells to become fully visible to the body’s immune system, thereby prompting the release of disease-fighting T-cells to eradicate the tumour.

Initial testing has yielded compelling results. In studies involving mice with bowel cancer, the iVAC vaccine achieved 100 percent effectiveness, leading to the complete eradication of tumours. Furthermore, separate laboratory tests conducted on human breast cancer cells demonstrated similar success, with the vaccine resulting in their total destruction.

For many decades, the primary approach to cancer treatment relied on established techniques such as chemotherapy and radiotherapy. Chemotherapy employs powerful drugs to halt the reproduction of malignant cells, but its effectiveness diminishes when cancer has metastasized, and it carries significant side-effects, including nausea, hair loss, and heart palpitations, due to its impact on both healthy and cancerous cells. Radiotherapy, which uses high-energy radiation to damage tumour DNA, eradicates approximately 40 percent of cancers on its own but can cause localized side-effects such as skin irritation.

The past 10 to 15 years have witnessed a transformation in the treatment of some cancers with the advent of immunotherapy drugs. This new generation of medicines, including pembrolizumab (used for advanced skin, lung, bladder, breast, and bowel cancers) and nivolumab (for kidney, head, and neck tumours), functions by unleashing the immune system, allowing it to detect and destroy rogue cancer cells. These drugs were developed in response to cancer cells' ability to 'hide' from the body's defences by releasing a protein called PD-L1, which binds to immune cells and instructs them not to attack. Immunotherapy drugs prevent this protein from binding, thus enabling immune cells to identify cancer cells as foreign and launch an aggressive assault.

The impact of existing immunotherapy treatments has been substantial, particularly in cancers like malignant melanoma, a form of skin cancer that was historically difficult to treat. Studies indicate that the five-year survival rate for melanoma patients receiving these drugs (typically via weekly or fortnightly infusions) has improved by around 50 percent since their introduction. Many melanoma patients are now surviving ten years post-diagnosis, a stark contrast to the average six-month survival time in the 1990s.

Despite these dramatic effects for some patients, current immunotherapy drugs do not benefit everyone; only about 40 percent of patients respond fully. In others, tumours may shrink temporarily only to resume growth weeks or months later. This limited efficacy is believed to occur because T-cells, the immune system's 'killer' cells, can become over-stimulated by a tumour's continuous presence, which can weaken their ability to attack effectively.

The new iVAC vaccine directly addresses these limitations. According to results published in February in the journal Nature, iVAC functions like standard immunotherapy by blocking the PD-L1 protein, preventing cancer cells from evading immune detection. Crucially, it simultaneously chemically reprogrammes cancer cells to proactively attract the attention of killer T-cells. It achieves this by inducing tumour cells to produce an antigen – typically a protein or fat – that is normally found on the surface of foreign invaders like viruses or bacteria. This antigen acts as a 'red flag,' effectively inviting the immune system to dispatch its soldier cells to attack and destroy the cancer.

While cancer cells already produce antigens, their signal is often weak, enabling tumours to escape the full force of the immune system. Developed by scientists at Peking University in China, the iVAC vaccine significantly amplifies this antigen response, allowing the body’s defences to react much more aggressively. The developers intend to test the vaccine on patients in the coming years, aiming to improve survival rates for the most challenging tumours, though the specific cancers to be targeted and potential side-effects remain under investigation.

Experts in the field are optimistic about this new approach. Professor Tim Elliott, an immuno-oncology specialist at the University of Oxford, highlights the immense promise of drugs that both prevent immune evasion and compel cancer cells to attract killer T-cells. He notes, 'It combines two mechanisms in one drug and is generating a lot of excitement,' adding that similar intravenous approaches are already being explored in trials. However, challenges persist. Professor Karl Peggs, a professor of cancer immunotherapy at University College London Hospitals NHS Foundation Trust, acknowledges the scientific elegance of delivering these two elements of treatment for mice experiments but points out the clinical difficulties. Direct tumour injection is feasible for single large masses, but it becomes considerably more challenging when cancer is widely disseminated in numerous tiny tumours, or when tumours are small, inaccessible, or hard to locate.