An experimental lung cancer drug from Akeso and Summit Therapeutics reduced the risk of death by 34% in a closely watched late-stage trial, according to results released Sunday.

When combined with chemotherapy, the drug kept people with squamous non-small-cell lung cancer alive for a median of four months longer than the standard combination of immunotherapy and chemotherapy, a result that was statistically significant, according to an abstract released Sunday ahead of a presentation at the American Society of Clinical Oncology’s annual meeting. The Phase 3 trial was conducted in China, and a global Phase 3 study is ongoing.

“The fact that it shows an improvement in overall survival in a difficult-to-treat patient population is very encouraging,” said Dr. Suresh Ramalingam, executive director of the Winship Cancer Institute of Emory University. “I’m mindful of the fact that this trial was done exclusively in China, and that brings up the question of how do these data apply to patient populations outside of China, and that will require future investigations.”

Called ivonescimab, the bispecific antibody targets PD-1 — similar to Merck’s best-selling drug Keytruda —and VEGF — similar to Roche’s Avastin. It’s become the subject of intense debate in the oncology and investment communities. Some say ivonescimab and similar drugs could be a successor to Merck’s wildly successful cancer drug Keytruda, while others warn it’ll disappoint like other once-promising ideas such as drugs targeting TIGIT, an immune receptor.

The dueling narratives are reflected in the stock price of U.S.-based Summit Therapeutics, which licensed the rights to ivonescimab outside of China from Akeso. Shares of Summit have skyrocketed nearly 600% in the two years since Summit said ivonescimab more effectively controlled tumors than Keytruda in a separate China trial. The stock has slid in the past month over concerns the drug won’t be as effective in a global population.

Previous studies have showed ivonescimab can effectively control tumors, an endpoint known as progression-free survival. That’s typically not enough to seek approval from the U.S. Food and Drug Administration, which wants proof that cancer drugs can keep people alive longer. Older VEGF drugs that effectively controlled tumors struggled to improve survival, which raised doubts that ivonescimab’s early promise would hold.

In the Harmoni-6 trial being presented Sunday, ivonescimab combined with chemotherapy kept people alive for a median of 27.9 months versus 23.7 months for people who received a standalone PD-1 drug and chemotherapy, an improvement of four months.

“It’s not clear how meaningful that is,” said Dr. Deborah Doroshow, associate professor of medicine, hematology and medical oncology at the Icahn School of Medicine at Mount Sinai. “It’s certainly, it’s not two months, but it’s also not a huge difference, and I think in terms of whether or not living four months longer is meaningful absolutely depends on the person who is living it.”

People receiving immunotherapy in the control group lived an average of six months longer than expected, raising questions about whether the trial enrolled a representative patient population and whether the advantage of ivonescimab might be better than reported in the study, said Doroshow, who serves on the steering committee for the ongoing Harmoni-3 global trial of ivonescimab.

One possible reason for the discrepancy is that the study was conducted in China, where people have historically responded better to standalone PD-1 and VEGF drugs, said Emory’s Ramalingam. The only way to determine whether combining the two in one molecule produces different results for broader populations is to run additional studies in the West, he said.

Until then, Ramalingam called the trial results “good news” for Chinese patients.

“There is a new approach in squamous cell lung cancer that extends survival by about four months, which is a substantial improvement given that this is a patient population where progress has come in small steps,” he said.

Summit plans to report progression-free survival results from squamous patients in the global Harmoni-3 trial in the second half of this year. It expects to share results from non-squamous patients in the first half of next year.

One purported benefit of PD-1/VEGF-targeting drugs is the ability to give them safely to people with squamous lung cancer, a subset most commonly caused by smoking. These tumors tend to crop up near major blood vessels in the lungs, and blocking VEGF can prevent those blood vessels from repairing themselves, leading to potentially fatal hemorrhaging.

In the trial being presented Sunday, bleeding of any severity occurred in almost one-quarter of people in the ivonescimab group, twice as much as in the control group. Less than 3% of the cases were considered severe versus about 1% of people who received the PD-1 drug tislelizumab, according to slides that will be presented Sunday where the presenter describes ivonescimab’s safety as comparable.

More broadly, drugmakers and investors alike want to know whether PD-1/VEGF drugs will succeed Keytruda and similar drugs like Bristol Myers Squibb’s Opdivo as mainstay treatments. Checkpoint inhibitors like Keytruda have transformed the treatment of lung cancer and are now used in dozens of other cancers. Keytruda alone has 44 indications and generated more than $30 billion in sales for Merck last year.

Replacing Keytruda everywhere it’s used today and potentially expanding into new indications would create “a very large market,” said Leerink Partners analyst Daina Graybosch. That prospect has prompted a rush of dealmaking.

Licensing deals involving PD-1 drugs reached $30 billion last year, nearly doubling the previous peak of $16 billion in 2017, a few years after Keytruda and Opdivo reached the market. Merck and Bristol Myers Squibb were part of the recent rush, with both companies signing potentially multibillion dollar deals for PD-1/VEGF drugs.

But it’s unlikely that ivonescimab and similar drugs will be as broadly used, said Ethan Smith, oncology director at Norstella, especially as they face more competition from other emerging drugs like antibody drug conjugates than Keytruda had when it entered the market more than a decade ago.

Data from one antibody drug conjugate from Merck and partner Kelun is also being presented this weekend at the ASCO meeting. The experimental drug cut the risk of tumor progression by 65% in a study of lung cancer conducted in China, according to an abstract released ahead of the meeting.

While Merck thinks there will be places for PD-1/VEGF drugs and is excited about the one it’s developing, the company doesn’t expect them to become the next Keytruda, said Dr. Marjorie Green, Merck’s head of global oncology clinical development.

“It’s an exciting time in oncology,” said Green. “I never thought that we would be in a position in lung cancer to debate about which of the new therapies is the best because there just have not been a lot of advances. Keytruda has just been a cornerstone therapy and people are like, ‘What’s going to displace it?’ And I think it’s good news for people who are unfortunately diagnosed with lung cancer that we’re in position to say, you know what, there might be multiple options of things that we can do, and then hopefully add them together and help even more.”

Marie Phelan said she had never heard of MDMA before spotting a flyer seeking veterans suffering from post traumatic stress disorder.

Now, she says the psychoactive drug more commonly known as ecstasy or molly has changed the trajectory of her life.

“My experience of MDMA was that it just cracked my heart wide open,” said Phelan who enlisted in the U.S. Army Reserve in 1999 and was deployed to Iraq in 2003.

“I was carrying this big heavy rucksack and I just put it down on the beach and I started unpacking it one little teeny tiny thing at a time and setting each little thing out on the waves,” Phelan said of the release from the treatment.

Phelan isn’t alone turning to alternative treatments for trauma. She is among a small group of Americans who have undergone psychedelic-assisted therapy through clinical trials studying new approaches to mental health treatment.

Now, access to those therapies is closer than ever to being expanded more broadly, bringing new options for patients and opportunities for companies — but also new scrutiny about safety and effectiveness.

In April, President Donald Trump signed an executive order aimed at accelerating research into psychedelic drugs for mental illness. The move came as his administration issued priority review vouchers to three companies developing psychedelic or MDMA-like therapies — Compass Pathways, Usona Institute and Transcend Therapeutics — aimed at speeding up parts of the FDA review process.

The order marks a notable shift in tone from Trump’s first term, when his administration took a harder stance on cannabis and other controlled substances. This time, the White House said psychedelic compounds “show potential in clinical studies to address serious mental illnesses for patients whose conditions persist after after completing standard therapy.”

Investors quickly piled into the sector. Shares of psychedelic drug developers such as Compass Pathways and other rivals tied to the space rallied following the announcement, with Wall Street analysts arguing the order could legitimize an industry long viewed as fringe.

The science, however, remains deeply debated, raising questions about how much room the segment has to grow.

Clinical research around some of these compounds has shown promising results. In late-stage trials sponsored by the nonprofit psychedelic research advocacy group Multidisciplinary Association for Psychedelic Studies, roughly 71% of participants with severe PTSD no longer met diagnostic criteria for the disorder after MDMA-assisted therapy sessions.

The FDA rejected a previous application for MDMA-assisted therapy in 2024, citing concerns around the design of that same late-stage study and the need for additional data. Some psychedelic researchers viewed that decision as evidence the agency remains cautious despite mounting public enthusiasm.

Countries outside the United States have already begun loosening restrictions. Australia became the first country to allow authorized psychiatrists to prescribe MDMA and psilocybin for certain mental health conditions in 2023. Researchers in Canada, Switzerland and the United Kingdom have also expanded clinical studies examining psychedelic-assisted therapies.

Even so, Weiss cautions that not all psychedelic compounds carry the same risks — or the same amount of evidence supporting their use.

“Psychedelic compounds, they have different safety profiles, different risks,” said Weiss. “Ibogaine has particularly high cardiovascular risks, and so what needs to be done is a very measured, methodical weighting of the safety and the efficacy between ibogaine and other compounds.”

The White House executive order specifically referenced accelerating research of ibogaine. But unlike psilocybin or MDMA-assisted therapy, ibogaine has not undergone large-scale clinical trials in the United States and has been linked to potentially serious cardiovascular side effects.

Weiss said the real worry among some researchers is not that psychedelic therapies are ineffective, but that political momentum could outpace the scientific process.

“My biggest concern would be that FDA standards are relaxed for politically motivated reasons,” he said. “It’s not clear that that is the case, but what’s required is a lot more scientific research and a very objective interpretation of the risks and benefits.”

Kabir Nath, Compass Pathways CEO, said his company is adhering to the same standards the FDA holds for all drugs. He said the company would not have started the process of submitting its drug, COMP360 Psilocybin, for approval in the first place if it felt the data was insufficient.

Even supporters of psychedelics used as treatment acknowledge the therapies are far more complex than taking a prescription pill at home. Most psychedelic-assisted therapy trials involve hours of preparation with clinicians, supervised treatment sessions and follow-up integration therapy afterward.

The treatments also come with risks. Patients can experience panic attacks, paranoia, elevated heart rates or psychological distress during sessions. In some clinical environments, doctors use so called “rescue drugs” like benzodiazepines or antipsychotic medications to calm patients experiencing severe adverse reactions or overwhelming hallucinations.

Phelan said her own experience with MDMA-assisted therapy felt less like intoxication and more like confronting years of trauma in a controlled setting.

For veterans’ advocates like Juliana Mercer, executive director of nonprofit Healing Breakthrough, the administration’s order represents validation for patients who have spent years pushing for broader access to alternative mental health treatments. Mercer, a U.S. Marine Corps veteran, said psychedelic-assisted therapy “completely changed” her life after she struggled with trauma.

“One of the things that this experience was able to give me was that permission to heal,” said Mercer.

As the Trump administration pursues VA staffing cuts and deeper military involvement with Iran, some veterans are increasingly questioning the prioritization of their care.

Thus, some critics of the Trump administration have said that the executive order’s timing is of particular importance as the president attempts to gain back veteran support ahead of the midterm elections.

Phelan, however, rejected the idea that backing for psychedelic therapies will translate into into political support for Trump.

“They’d made so many cuts to veteran benefits and medical services,” Phelan said. “Great, you did a good thing. You did a right thing … I can’t speak for how other people will react, but if that’s the intention, I doubt it’s effective.”

Some industry executives also argue the executive order may have less immediate impact than headlines suggest. Companies like Compass Pathways were already nearing the final stage of Phase 3 trials before the White House announcement, meaning FDA approval submissions were likely coming regardless.

Nath, CEO or Compass Pathways, said the order primarily signals broader political acceptance of the field.

“It certainly gives a significant tailwind, encouragement and validation,” Nath said.

— CNBC’s Ryan Baker contributed to this report