An innovative new treatment for tackling some of the toughest stomach cancers has shown promise in a phase 2 clinical trial, leading to noticeable improvements in tumor shrinkage and survival rates.

The treatment is a form of CAR T cell immunotherapy, where the body's own immune cells are sampled and then trained to better target cancer cells, before being reintroduced into the blood.

This specific therapy is called satricabtagene autoleucel, or satri-cel, and it targets the CLDN18.2 protein that certain tumors can use to grow. Patients given satri-cel in the trial lived around 40 percent longer, on average.

Other positive signs from the trial, carried out by researchers from institutions across China, were that in satri-cel patients, the cancer was more likely to shrink and take longer to worsen, compared with patients on standard cancer drugs.

The trial involved 156 participants with either gastric or gastroesophageal junction cancer, who hadn't responded to at least two existing treatments – essentially, people who were running out of options before the trial.

"In patients with heavily pretreated, advanced gastric or gastroesophageal junction cancer who have extremely limited treatment options and poor prognosis, satri-cel has demonstrated breakthrough efficacy with significant clinical benefits, including much improved progression-free survival, overall survival, and tumor response rates," says oncologist Lin Shen, from Beijing Cancer Hospital.

In the satri-cel group, patients lived a median average of 7.92 months compared to 5.49 months in the control group. In 22 percent of satri-cel patients, there was significant tumor shrinkage, compared to just 4 percent of the control patients.

The median time before the cancer worsened was 3.25 months with satri-cel, and 1.77 months without. These are impressive results, across a range of different measurements, and demonstrate the treatment can work.

"This brings new hope to patients with otherwise medically untreatable conditions," says Shen.

It's not all good news though: the satri-cel treatment almost always led to significant side effects, including a drop in blood cell counts. However, these side effects are manageable, the researchers suggest.

CAR T cell therapy has already been shown to be effective at treating blood cancers, and exciting results are beginning to appear for solid tumors such as brain cancer and pancreatic cancer. It looks as though we can soon add these gut cancers to the list as well.

It's more evidence that in general we're getting better at tackling cancer, and the growth of solid tumors. In the last year or two, researchers have been able to discover new ways of destroying cancer cells, and even turn cancer cells back into healthy ones.

What this isn't, however, is a cure – though this research might eventually lead to one. Rather, it helps to manage the cancer tumor, making the body's own immune cells better at fighting back against the malignant growth.

"We are further exploring satri-cel's potential in adjuvant settings and as first-line sequential therapies, aiming to intervene earlier in the disease course, extend patients' survival, and ultimately pursue potential cures," says Shen.

The research has been published in The Lancet.