New data show three-parent IVF does not always keep a mother's faulty mitochondria out of her baby

The stories

16 stories on this beat today.

Every story told the same way: what happened, who is involved, why it matters, how it works, the truth and the good news.

1. 01

   New data show three-parent IVF does not always keep a mother's faulty mitochondria out of her baby

   2 of 6

   children tested at a Ukrainian clinic who carried their mother's mitochondria back

   one at up to 72%, in data not yet published [1]

   3 of 8

   British children born by MRT with some of the mother's mitochondria

   at 5% to 16%, below the 50% level where symptoms are expected [1]

   75% to 100%

   less faulty DNA passed on, in Newcastle's patients

   Mary Herbert's count; she calls it lowering risk, not prevention [1]

   What happened

   • New data show babies made with three-parent IVF can carry back some of their mother's faulty mitochondria. [1]
   • Mitochondria are the tiny power plants inside cells. [1] They carry their own DNA, which children get from their mother. [1]
   • At a clinic in Ukraine, 2 of 6 children tested carried their mother's mitochondria back. [1] In one child it was up to 72%. [1]
   • The method is called mitochondrial replacement, or MRT. [1] It puts the parents' genes into a donor's egg that has healthy mitochondria. [1]
   • It was built to stop mothers passing on diseases caused by faulty mitochondria, some of them fatal. [1]
   • Britain and Australia are the only two countries whose laws plainly allow it, and the US bans it. [1]
   • Last year Newcastle University in Britain reported 8 children born this way, with no signs of disease. [1]
   • But 3 of those 8 carried some of their mother's mitochondria, at 5% to 16%. [1]
   • A study in Greece, published in 2023, used a second version of MRT. [1] Two of its 7 children carried 51% and 35% of their mother's mitochondria. [1]
   • The Greek and Ukrainian studies used MRT to treat infertility, not disease. [1] The Ukrainian mothers carried no known harmful faults. [1]
   • Disease symptoms are expected once faulty mitochondria pass about 50% of a cell's total. [1] The British children stayed below that line. [1]
   • The scientist Shoukhrat Mitalipov named the problem reversion in 2016. [1] His paper suggested it could make MRT fail in about 15% of cases. [1]
   • Britain still gave Newcastle a licence to use MRT in 2017. [1]
   • Jacques Cohen, a New York embryologist, wants MRT paused for families with mitochondrial disease. [1]
   • "To do it in a family affected by mitochondrial disease is to take a very big risk," he said. [1]
   • Mary Herbert, once head of the Newcastle team, says MRT cut passing on faulty DNA by 75% to 100%. [1]
   • She says it should be described as lowering the risk of disease, not preventing it. [1]

   Highest British child16%

   Greek child51%

   Ukrainian child72%

   Who is involved

   • Britain allows it
   • Australia allows it
   • United States bans it
   • Newcastle University the only British clinic licensed to offer MRT; it reported 8 children last year
   • Mary Herbert a scientist who once led the Newcastle team and now works at Monash University in Melbourne; she is preparing an Australian trial
   • Jacques Cohen a New York embryologist, an expert on early embryos; he wants MRT paused for families with mitochondrial disease
   • Nadiya Clinic a fertility clinic in Ukraine; it shared unpublished data on 6 children

   How it unfolded

   1. 2016 reversion described
   2. 2017 Newcastle licensed
   3. 2016 Mitalipov's team describes reversion [1]
   4. 2017 Newcastle gets a licence to use MRT [1]
   5. 2023 a Greek study finds 2 of 7 children with the mother's mitochondria [1]
   6. Last year Newcastle reports 8 children; 3 with some reversion [1]
   7. Now Australia and Belgium prepare their own studies [1]

   Why it matters

   Australia is preparing its own national test of MRT. [1] These results arrive as its regulators and researchers prepare to launch it. [1]

   How it works

   Biologists call this reversion: a few faulty mitochondria left in the egg take over as its cells divide. [1]

   Mitalipov's lab in Oregon swapped up to 99% of an egg's faulty mitochondria. [1] Yet with each round of cell division, the faulty share kept rising. [1]

   Seen it before

   Clear a garden but leave a few weed roots, and by summer the weeds can cover the bed again.

   The truth

   • What is really going on Separately, new data show three-parent IVF can let a mother's faulty mitochondria come back in some children, the people it was built to protect. [1]
   • Why it works on people A story about one child at 72% feels like a verdict on the whole method, though those mothers carried no known disease and the British children stayed below the 50% level where symptoms are expected. [1]
   • The Ukrainian figures are unpublished. [1] One outside embryologist, Jacques Cohen, has reviewed them. [1]
   • Who pays Families with mitochondrial disease — MRT was built for them, so if it reverts, they carry the risk that a child still gets the disease. [1]
   • Nobody knows yet

     Whether the reversion seen so far will harm any of the children.

     The British children are still being followed to see whether the faulty share grows, and the Ukrainian data have not been published. [1]

   What comes next

   Herbert's team at Monash University in Melbourne is preparing to ask Australia's government to allow a clinical trial. [1]

   In Belgium, Ghent University has approval to start with 7 patients in each of 2 groups. [1]

1. 02

   Servier's $1.55bn muscle drug fails

   What happened

   • Servier, a French drugmaker, said on Tuesday that its drug sevasemten failed to slow Becker muscular dystrophy. [2]
   • Becker is a rare form of muscular dystrophy, a muscle disease, and patients with it have no approved treatment. [2]
   • Servier bought the drug in June from Edgewise Therapeutics for $1.55 billion in cash. [2]
   • It also agreed to pay about $1 billion more if the drug reached set goals. [2]
   • Servier announced the failure of its final, long trial about 5 months after the purchase. [2] Some patients in it got a dummy drug. [2]
   • A smaller, earlier trial of sevasemten had shown promising results. [2]

   How it unfolded

   1. June Servier buys the drug
   2. November the final trial fails

   Why it matters

   STAT, a US health news site, called the failure a surprising setback for Servier and for patients. [2]

   How it works

   Drug developers call the final big test a phase 3 trial: the one an approval would rest on. [2]

   Sevasemten's phase 3 tested whether the promise of the smaller study would hold, and it did not. [2]

   Seen it before

   Doing well on one short quiz does not mean you will pass the full exam.

   The truth

   • Who gains Edgewise Therapeutics — It sold the drug to Servier for cash in June, before the final trial failed. [2]
   • Who pays People with Becker muscular dystrophy — With sevasemten failed, they remain without any approved treatment. [2]
   • Nobody knows yet

     Why Servier's drug failed its final trial after a smaller study looked promising.

     Servier says it is still analysing the full data, together with the earlier trials. [2]

1. 03

   Pfizer cuts six drug programs

   What happened

   • Pfizer stopped work on 6 drug programs in its latest 3-month update. [3]
   • The furthest along was a phase 2 drug for a lung disease called pulmonary arterial hypertension. [3]
   • It grew from a surprise finding: blocking a protein called BMP9 protected rodents from the disease. [3]
   • Pfizer ended its study for business reasons, not because of safety or how well it worked. [3]
   • Two of the cut programs were early obesity drugs, one of them a pair Pfizer got from Metsera. [3]
   • Within 3 months, Pfizer has dropped two opposite ways to act on GIPR, a body receptor linked to weight. [3]
   • The other cuts included 2 early cancer drugs that block a protein called KRAS. [3]

   Why it matters

   Rivals carry on: Eli Lilly sells a drug that uses one approach, and Amgen is testing one using the other. [3]

   How it works

   Drugmakers call this managing a pipeline: dropping projects for business reasons, as Pfizer did with its lung drug. [3]

   Seen it before

   A family with money for one holiday drops a trip they liked for one they like more.

   Why a big drugmaker ranks its medicines and cuts the lowest

   Drug companies' portfolio managers rank each medicine by its chance of approval times its likely sales, minus the cost still to come.

   The twist

   A safe medicine can be stopped because the same money looks more likely to pay off on another medicine in the same company.

   The picture

   6 of 6

   drug programs Pfizer stopped in one 3-month update

   Step by step

   1. 1 A drugmaker tests more medicines than it can afford to finish
   2. 2 Each gets a value: its chance of approval, times its likely sales, minus the cost still to come
   3. 3 New results or a stronger rival drug lower that value
   4. 4 The medicines at the bottom are stopped, even when they were safe
   5. 5 Their money moves to the medicines at the top

   The same force, elsewhere today

   Where this chain is also running, in today's other stories.

   • Pfizer cuts six drug programs

     Pfizer stopped its lung-disease drug for business reasons, not safety or results, in the same update that cut 5 other programs.

   • AbbVie drops a cancer antibody

     AbbVie judged the drug unlikely to beat the treatments patients already get, which lowered its likely sales, so it was stopped.

   • Teva stops a brain-disease trial early

     A midway check found little chance of success, which cut the drug's value, and Teva stopped the trial.

   • Lonza buys five US drug factories

     Merck KGaA sold its factory business to spend the money on the science work it ranks higher.

   Where you've seen this

   Film studios

   a studio shelves a half-made film when another project looks likelier to sell tickets

   Farms

   a farmer ploughs in a healthy crop when another crop would pay more for the same field

   School budgets

   a school drops a club that works because the same money buys more teaching elsewhere

   The catch

   The ranking rests on guesses about chances and sales that companies do not publish, so a drug cut for business reasons might have worked.

   And the whole of it

   The patients in Pfizer's lung study and Teva's trial had no part in these rankings. Each company ranks only its own medicines, so nobody decides what all the cuts add up to for people with one disease.

   The truth

   • Who pays Patients in Pfizer's lung-disease study — Their study, due to run until 2028, ended early for business reasons, not because the drug was unsafe. [3]

1. 04

   Novartis ends a brain-drug deal early

   What happened

   • Novartis, a Swiss drugmaker, ended an $800 million deal with BioArctic, a Swedish company, after 14 months. [4]
   • BioArctic announced the end on Monday afternoon. [4] Novartis had paid $30 million at the start, in August 2025. [4]
   • BioArctic's technology, BrainTransporter, is designed to help large drug molecules pass into the brain. [4]
   • The brain is guarded by the blood-brain barrier. [4] It has kept large drugs from reaching diseases like Alzheimer's and Parkinson's. [4]
   • BioArctic also helped develop Leqembi, an Alzheimer's drug, with the company Eisai. [4]

   Who is involved

   • BioArctic helped make Leqembi
   • Eisai its partner

   Why it matters

   The ending follows failed final trials for two Novartis drugs, one for a muscle-wasting disease and one for the heart. [4]

   How it works

   Dealmakers call these milestone payments: money paid only when the work hits set goals, as in this deal. [4]

   So when Novartis walked away, the $772 million BioArctic could have earned stopped with it. [4]

   Seen it before

   A builder paid for each finished floor gets nothing more once the owner cancels the house.

   The truth

   • BioArctic said the decision had nothing to do with its technology. [4] Novartis gave no reason in Fierce Biotech's report. [4]
   • Who gains BioArctic — It keeps the money Novartis paid at the start, and its other brain-drug deals with Bristol Myers Squibb and Eli Lilly. [4]
   • Nobody knows yet

     Why Novartis ended the BioArctic deal.

     BioArctic says the reason had nothing to do with its technology, and Novartis gave no reason in Fierce Biotech's report. [4]

2. 05

   AbbVie drops a cancer antibody

   What happened

   • AbbVie, a big drugmaker, has stopped developing livmoniplimab, a cancer drug, Fierce Biotech reported. [5]
   • AbbVie said the drug's benefit looked limited next to treatments patients already get, in bowel and lung cancer. [5]
   • It is an antibody, a lab-made protein, meant to block a signal called TGF-beta that holds back the immune system. [5]
   • In 2024, a first study gave it with a second AbbVie drug to 12 liver-cancer patients. [5] Tumours shrank in 42%. [5]
   • A bigger trial against Keytruda, Merck's best-selling cancer drug, was due to report in 2031. [5]

   Why it matters

   AbbVie's cancer pipeline now leans on drugs that carry a poison straight to tumour cells. [5]

   How it works

   Drug developers call the best treatment patients get now the standard of care, which a new drug must beat. [5]

   AbbVie judged livmoniplimab unlikely to beat it, so it stopped years before the big trial would end. [5]

   Seen it before

   A new phone has to be better than the one people already own, or nobody switches.

   AbbVie judged the drug unlikely to beat the treatments patients already get, which lowered its likely sales, so it was stopped.

   The idea, in story 03: Why a big drugmaker ranks its medicines and cuts the lowest →
3. 06

   Teva stops a brain-disease trial early

   What happened

   • Teva, long known for cheap copies of medicines, stopped a trial of its pill emrusolmin on Monday. [6]
   • Emrusolmin was being tested in multiple system atrophy, a rare disease in which brain cells die. [6]
   • The trial was meant to have 350 patients, began in 2024 and was due to finish next year. [6]
   • An independent panel checking the results midway found little chance the trial would meet its main goal. [6]
   • No safety problems were seen. [6] Teva is developing the drug with Modag, a German company. [6]
   • Teva will study the data before deciding the drug's future. [7]

   How it unfolded

   1. 2024 the trial starts
   2. Monday the trial is stopped
   3. Next Teva reviews the data

   Why it matters

   Emrusolmin was once a key part of Teva's move from copies into new medicines. [6]

   How it works

   Statisticians call this futility: a midway check finds a trial has little chance to succeed, as Teva's did. [7]

   Seen it before

   If you are 10 marks short with one easy question left, you stop hoping to pass.

   A midway check found little chance of success, which cut the drug's value, and Teva stopped the trial.

   The idea, in story 03: Why a big drugmaker ranks its medicines and cuts the lowest →

   The truth

   • Who pays People with multiple system atrophy — A medicine being tested for them was stopped before the trial finished. [6]
   • Nobody knows yet

     Whether Teva will keep developing emrusolmin at all.

     Teva says it will review the trial data before deciding. [7]

4. 07

   Vertex awaits a kidney-drug decision

   What happened

   • The FDA, the US drug regulator, could approve Vertex's kidney drug povetacicept by the end of November. [8]
   • The drug treats IgA nephropathy, a rare disease that gets worse over time. [8]
   • Vertex says the team that will sell it is "fully hired, trained and ready to go". [8]
   • A petition in late October asked the FDA to require regular antibody checks on people taking it, for safety. [8]
   • Two similar medicines are already on sale. [8] Vertex wants to sell its drug as a monthly shot people give at home. [8]

   Why it matters

   Last quarter, more than 95% of Vertex's sales came from cystic fibrosis drugs. [8] Its kidney drugs are its next big test. [8]

   The truth

   • Nobody knows yet

     Whether the FDA will approve Vertex's kidney drug by the end of November, and with what safety checks.

     A petition asks for regular antibody checks, and the FDA has not yet decided. [8]

5. 08

   Lonza buys five US drug factories

   What happened

   • Lonza, a Swiss company that makes medicines for other drug firms, is buying 5 US sites from Merck KGaA. [9]
   • Merck KGaA is a science company based in Darmstadt, Germany. [9]
   • The deal takes Lonza from 4 to 9 US sites. [9] About 1,100 staff will join it. [9]
   • The sites make parts for newer medicines, such as the virus shells that carry gene therapies into cells. [9]
   • Lonza gave no exact price, only "low- to mid-triple-digit millions" of Swiss francs. [9]

   How it unfolded

   1. This week deal signed
   2. Mid-2027 deal completed

   Why it matters

   Lonza says the US is the biggest market for new medicines, so the sites bring it closer to its customers. [9]

   How it works

   Economists call this outsourcing: drug firms pay a specialist like Lonza to make their medicines. [9]

   Merck KGaA says selling lets it put its money into its main science business. [9]

   Seen it before

   A bakery can sell its delivery vans, spend more on ovens, and pay a courier instead.

   Merck KGaA sold its factory business to spend the money on the science work it ranks higher.

   The idea, in story 03: Why a big drugmaker ranks its medicines and cuts the lowest →

   The truth

   • Who gains Lonza — It gets US factories for newer medicines in the market it calls the biggest for them. [9]
   • Nobody knows yet

     What Lonza is paying for the five sites.

     Lonza gave only a range, in the low to mid hundreds of millions of Swiss francs. [9]

   What comes next

   The sale should be completed in mid-2027. [9]

6. 09

   A Chinese psoriasis pill passes its final trial

   What happened

   • InventisBio, a drug company in Shanghai, said its pill nomelcitinib passed a final-stage trial in the skin disease psoriasis. [10]
   • The trial gave 391 people in China one of 2 doses of the pill, or a dummy pill. [10]
   • After 16 weeks, more than 70% of those on the pill had skin at least 90% clearer. [10]
   • Rival pills from Takeda and Alumis reached that mark in about 52% to 61% of patients, in their own trials. [10]

   Why it matters

   Pills of this kind fetch high prices: Takeda paid $4 billion upfront for its rival in 2022. [10]

   The truth

   • Comparing trials run in different places can mislead, Fierce Biotech warns. [10] InventisBio has not yet shared the dummy-pill results. [10]
   • Nobody knows yet

     How well InventisBio's pill did against a dummy pill.

     The company has not yet shared the dummy-pill group's results. [10]

   Good news

   • More than 80% of patients on the pill had clear or almost clear skin by week 16. [10]

   What comes next

   InventisBio is also comparing its pill directly with Sotyktu, a rival from Bristol Myers Squibb, in China. [10]

7. 10

   Recursion's pill shrinks gut growths

   What happened

   • Recursion, a company that uses AI to find drugs, reported results for its pill REC-4881 on Monday. [11]
   • It is being tested in FAP, a rare inherited disease that fills the gut with growths called polyps. [11]
   • Many people with FAP have their colon removed to prevent cancer. [11] No drug for it is approved in the US. [11]
   • After 12 weeks on the pill, 13 of 15 patients had a smaller total of polyps. [11] The median cut was 47%. [11]

   Who is involved

   • Recursion uses AI to find drugs
   • Takeda made the pill

   How it unfolded

   The pill was first made by Takeda, a drugmaker, and Recursion's AI found where it might work. [11]

   Why it matters

   Doctors still send people with FAP for major surgery and frequent scopes, said Bryson Katona, a study doctor. [11]

   How it works

   Drug developers call this repurposing: giving an existing drug a new disease, as Recursion did with Takeda's. [11]

   Seen it before

   An old spare phone can become a baby monitor once someone finds a new job for it.

   The truth

   • The study was small, and Recursion warned that its best result was not typical. [11]
   • Who gains Takeda — Recursion owes it payments and a share of sales if REC-4881 reaches the market. [11]

   Good news

   • In a small study, 13 of 15 people with FAP, an inherited disease that fills the gut with growths, had a smaller total of polyps after 12 weeks on Recursion's pill.

   What comes next

   Recursion plans its larger, final-stage trial for the second half of 2027. [11]

8. 11

   England tests blood tests for many cancers

   What happened

   • About 200 family doctors' surgeries in England will offer a trial of blood tests that look for many cancers. [12]
   • More than 20,000 patients aged 45 or over, with signs like pain or lasting bloating, can take part. [12]
   • The tests look for proteins or bits of DNA in the blood that may signal cancer. [12]
   • The trial, STRIDE-RCT, is led by the University of Birmingham. [12] It will check whether the tests are accurate enough for wider use. [12]
   • About 71,000 people in England get 5 of these cancers each year, and nearly 35,000 die of them. [12]

   How it unfolded

   An earlier NHS trial of another test, Galleri, missed its main goal of cutting late-stage cancers. [12]

   Why it matters

   These cancers in the belly are often found only after they have spread. [12] Finding them earlier gives patients a much better chance. [12]

   How it works

   Doctors call this triage: deciding which patients with vague symptoms need tests first, as these blood tests aim to. [12]

   Seen it before

   A school nurse sends the pupils who look worst to the doctor first.

   The truth

   • A positive result does not always mean cancer. [12] A negative one is not a guaranteed all-clear. [12]
   • Nobody knows yet

     Whether the new blood tests are accurate enough for wider NHS use.

     That is what the STRIDE-RCT trial is set up to find out. [12]

9. 12

   Kenya sends five Ebola patients home

   What happened

   • Kenya discharged 5 Ebola patients on 3 November, after each tested negative 5 times. [13]
   • Another 46 people finished 21 days of watching for symptoms. [13]
   • Kenya has had 9 confirmed cases and 2 deaths, all linked to one person who brought the virus in. [13]
   • Saudi Arabia has put travel limits on Kenya because of Ebola. [13]
   • Africa CDC, the African Union's public health agency, asked Saudi Arabia to lift them. [13] Its head said "Africa needs partnership, not punishment". [13]

   How it unfolded

   The virus came from Congo, where more than 10,300 cases have been confirmed since May. [14]

   Why it matters

   Africa CDC warns that limits like these can stop countries reporting outbreaks quickly. [13]

   How it works

   Epidemiologists call this contact tracing: following each case's contacts for 21 days, as Kenya did with 46 people. [13]

   Seen it before

   When one pupil gets nits, the school checks everyone in that class.

   The truth

   • By Africa CDC's count, donors have paid about 1 billion of the 3 billion they pledged for the outbreak. [13]
   • Who pays Travellers and traders from Kenya — Saudi Arabia's travel limits stay in place while Africa CDC asks for them to be lifted. [13]

   Good news

   • No new case has been confirmed in Kenya since 19 October. [13]
10. 13

    A study will test 80,000 blood samples for brain disease

    What happened

    • Two companies will measure hundreds of blood proteins in 80,000 samples from UK Biobank, a big health study. [15]
    • Alamar Biosciences makes the test. [15] Nightingale Health will run it in its own labs. [15]
    • The aim is to find signs of Alzheimer's and Parkinson's years before symptoms appear. [15]
    • Many of these proteins are so scarce that standard tests barely pick them up. [15]
    • Dementias affect more than 55 million people worldwide, and Parkinson's more than 12 million, the companies say. [15]
    • The Michael J Fox Foundation, Alzheimer's Research UK and LifeArc are paying for it. [15]

    Who is involved

    • Alamar Biosciences makes the test
    • Nightingale Health runs it

    How it unfolded

    1. End of 2027 the study finishes
    2. After the data open to researchers

    Why it matters

    It rests on a growing view that these diseases begin years before they are diagnosed. [15]

    How it works

    Scientists call such a blood sign a biomarker: a measure that flags a disease, as these proteins might. [15]

    Seen it before

    A smoke alarm can warn of a fire before anyone sees flames.

    What comes next

    The work should finish by the end of 2027. [15] Researchers around the world can then apply to use the data. [15]

11. 14

    Worms show how the brain forgets on purpose

    What happened

    • Scientists at Kyushu University found how a tiny worm deliberately forgets a smell it learned. [16]
    • The worm, C. elegans, has only 302 nerve cells, and each one has been identified. [16]
    • A small protein called NLP-47 starts the forgetting, passing a signal along a chain of nerve cells. [16]
    • When worms learned 2 smells at once, the system erased only one of them. [16]
    • Worms with the system switched off held on to their smell memories longer. [16]
    • The study was published in the journal Current Biology. [16]

    Why it matters

    Humans have similar receptors, and in rodents they sit in the brain's memory centre. [16]

    How it works

    Neuroscientists call this active forgetting: the brain erasing a memory on purpose, as the worm's circuit does. [16]

    Seen it before

    Clearing old photos from a full phone makes room, and you choose which ones go.

    The truth

    • This is a worm study, and the authors only suggest the system may work the same in other animals. [16]
12. 15

    A gene-editing start-up raises $35 million for ALS

    What happened

    • Specific Biologics, a gene-editing company in Toronto, raised $35 million, more than it first planned. [7]
    • Hatteras Venture Partners led the round. [7] A fund run by the Business Development Bank of Canada also joined. [7]
    • The money will pay for an early trial in people with ALS, a nerve disease, who carry certain gene faults. [7]
    • The trial will use markers in the body to check the therapy works as intended. [7]

    Who is involved

    • Hatteras Venture Partners led the round
    • Business Development Bank of Canada joined

    Why it matters

    The extra money lets the company take its most advanced therapy into people. [7]

13. 16

    A new company tests drugs for heart and lung disease

    What happened

    • CinRx Pharma and Graviton BioScience formed a joint company, CinRock Pharma, on Monday. [7]
    • CinRock will test 2 drugs that block ROCK2, an enzyme, in a lung disease and other heart and blood-vessel diseases. [7]

    Who is involved

    • CinRx Pharma pays for it
    • Graviton BioScience brings the drugs

    How it unfolded

    CinRx created a biotech that AstraZeneca bought in 2023. [7]

    Graviton, led by Sam Waksal, worked on ROCK2 drugs for rare brain disorders with Ovid Therapeutics. [7]

    1. 2023 AstraZeneca buys a CinRx biotech
    2. Monday CinRock is formed

    Why it matters

    The lung disease, pulmonary arterial hypertension, is the one Pfizer's dropped drug was meant for. [3][7]