ASCO 2024: data on weight loss drugs and a melanoma vaccine, a test that can predict breast cancer relapse, and more

We had research experts on the ground in Chicago at the 2024 American Society of Clinical Oncology (ASCO) annual meeting, the world’s biggest cancer conference. They’ve helped put together this guide to some of the most important announcements.

The studies discussed here aren’t over yet, so we don’t have full peer-reviewed papers explaining all the data and methods behind the findings. It’s best to think of them as waypoints in a continuing journey. They tell us where cancer research could be heading over the coming years, not where cancer prevention or cancer treatment is right now.  

Signs that weight loss drugs could help prevent cancers linked to obesity

Headline-making weight loss drugs like Ozempic and Wegovy could also lower people’s risk of developing cancers linked to obesity, according to US researchers.

“The link between obesity and multiple cancers is proven,” said Professor Charles Swanton, our chief clinician, who has been representing us at ASCO. “While these are effective drugs to manage weight loss, it’s still early days in our understanding of whether they can reduce people’s risk of cancer.”

Ozempic and Wegovy are the best-known examples of drugs called GLP-1 receptor agonists (GLP-1 RAs), which mimic the action of GLP-1, a hormone made by the small intestine. These drugs were originally used to treat type 2 diabetes, but they can also support weight loss by making people feel more full.

Researchers at Case Western Reserve University in Ohio found patients taking the drugs were 19% less likely to develop any of the 13 cancers we know are linked to being overweight. These include ovarian, liver, colorectal, pancreatic, bowel and breast cancer.

“This large, retrospective study suggests a link between weight loss drugs and a reduced risk of obesity related cancer after just one year, but more research is needed to prove this association,” explained Swanton.

Two other studies presented at ASCO suggest that GLP-1 RAs could reduce the risk of breast cancer returning after treatment. Those are exciting signs, but we still don’t know exactly what they mean.

“Well-designed prospective trials with randomised data will provide more clarity on the potential and safety of weight loss drugs to lower people’s risk of cancer,” Swanton said.

A test to predict if breast cancer will return

ASCO also brought news of another tool we might be able to use to tackle breast cancer relapse. A DNA blood test could tell doctors whether the disease will return after surgery, according to results from a proof-of-principle study.

The test works by picking out tiny amounts of cancer-specific DNA (called circulating tumour DNA, or ctDNA) that can escape from a tumour and persist in the blood even after initial treatment.

Although ctDNA can’t be picked up by the scans and tissue samples (biopsies) doctors currently use to look for cancer, it raises the risk of disease returning.

A team led from the Institute of Cancer Research in London have found that the NeXT Personal liquid biopsy test can show whether ctDNA remains after surgery and use that information to predict when breast cancer will relapse.

In a 76-patient study, the new test used ctDNA to correctly identify all 10 women whose breast cancers went to on to relapse – long before these returning cancers became visible on scans. The data released so far also suggests there were no false-negatives: no one the test said was ctDNA-free has seen their cancer return.

Researchers think the test could be used to show which women need preventive therapy after surgery and which can be spared further treatment. The next step is to study how well that works in practice across bigger patient groups.

“Early detection is key to improving cancer survival, so it’s positive that this study lays the foundation for a blood test that predicts the return of cancer in people who have had early breast cancer surgery,” said Dr Catherine Elliot, our director of research.

“Researchers measured circulating tumour DNA (ctDNA) to help find cancer cells that remain after surgery. The results show a strong correlation between ctDNA detection and relapse, with cancer returning around one year after detection.

“Results like this demonstrate how liquid biopsy technology can be used to inform kinder, more targeted treatment for patients based on their risk of recurrence.”

Melanoma cancer vaccine results “extremely impressive”

The first vaccine treatment for the form of skin cancer usually caused by sun damage could halve the risk of patients dying or the disease returning, according to early trial results.

Researchers led by a team at New York University combined a vaccine using the same mRNA technology as many COVID jabs with an established immunotherapy called pembrolizumab. It was given to patients after they had surgery to remove stage 3 or stage 4 melanoma.

After three years, 75% of those who had the vaccine and pembrolizumab were still cancer-free, compared to 56% of people who only received pembrolizumab.

Iain Foulkes, our executive director of research and innovation explained that the results “show positive signs of the mRNA vaccine’s long-lasting effectiveness”, although larger and longer trials are still needed.

Unlike traditional vaccines, which are used to prevent disease, cancer vaccines are used to treat cancers. The vaccine used in this trial, mRNA-4157 (created by Moderna), is different for every patient. Scientists personalise it to help people’s immune system identify their specific cancer cells. Pembrolizumab, a type of immunotherapy called a checkpoint inhibitor, supports this by effectively taking the brakes off of immune cells called T cells.

Speaking to journalists at ASCO, Swanton called the results “extremely impressive”.

“The new vaccine approach is another piece of the puzzle that will allow more patients to be cured, hopefully, or fewer patients to suffer disease relapse. Ultimately it will contribute to survival rates improving continually over the next decades and more.”

Immunotherapy before surgery clears 10 times more bowel cancers with a specific mutation than chemo

On its own, pembrolizumab is much more effective than chemotherapy for people whose bowel cancers have a particular genetic profile, according to interim results from the phase 2 NEOPRISM-CRC trial.

Pembrolizumab, also known by the brand name Keytruda, is already used to treat non-small cell lung cancer, Hodgkin lymphoma and bladder cancer, as well as melanoma. A research team led from University College London (UCL) tested it before surgery in stage two and three bowel cancer patients with a mismatch repair (MMR) deficiency that limits cancer cells’ ability to fix DNA damage.

The results presented at ASCO indicate that more than half of the 32 people on the trial treated with pembrolizumab prior to surgery had no signs of cancer after their operations. Other studies have shown that the same is true for just 4% of people treated with chemotherapy.

The approach also meant that patients didn’t need follow-up chemotherapy after their operations, protecting them from potentially difficult side effects.

“This small single arm study adds to established evidence that checkpoint inhibitor drugs help to treat bowel cancer before surgery by activating the immune system’s anti-cancer functions in patients with a specific DNA repair abnormality,” explained Swanton.

In total, around 10-15% of patients with stage two or three bowel cancer have MMR deficient cancer cells. That suggests the treatment could one day be an option for around 2,000-3,000 people in the UK every year.

As the trial continues, researchers based at the Cancer Research UK and UCL Cancer Trials Centre will assess whether patients treated with pembrolizumab remain cancer free over a longer period of time.

“More work needs to be done to assess pembrolizumab before it could be considered standard treatment, but given the quality of the outcomes in this trial I think it’s possible that we could see it in the clinic within a couple of years if subsequent trials are similarly successful,” said Dr Marnix Jansen, a clinician and scientist working from the UCL Cancer Institute and University College London Hospital.

Lorlatinib stops some lung cancers for longer than any other drug

Remarkable results from the CROWN trial suggest a targeted drug called lorlatinib could stop a form of advanced non-small cell lung cancer “in its tracks”.

CROWN’s researchers are comparing lorlatinib to a similar drug called crizotinib as treatments for the 3% to 5% of non-small cell lung cancers with ALK (anaplastic lymphoma kinase) mutations. So far, the trial has shown that lorlatinib can stop these advanced cancers from growing or spreading for longer than any lung cancer drug in history.

“Showcasing the power of cancer growth blocker drugs, this study could present us with an effective way of stopping cancer in its tracks and preventing it from spreading to the brain,” explained Swanton, who leads our flagship lung cancer study, TRACERx.

“The groundbreaking results show that over half of the patients who took lorlatinib did not suffer a progression in their disease after five years. In contrast, over half of the patients who took crizotinib experienced disease progression after just nine months.”