Cancer
New insights into the origins of ovarian cancer

Researchers have identified a novel trigger of a deadly form of ovarian cancer: a subset of progenitor cells that reside in fallopian tube supportive tissue, or stroma.
The discovery of these high-risk cells could pave the way for better approaches to prevent and detect high-grade serous ovarian cancer (HGSOC), the most common form of ovarian cancer, which kills more than 12,000 women in the U.S. each year.
“Ovarian cancer is the leading cause of death from gynaecologic cancer in the Western world, but we currently have no way to detect it early and no prevention strategies apart from surgical castration, which is only indicated in high-risk women,” said co-senior author Lan Coffman, associate professor at the Pitt School of Medicine and member of Magee-Womens Research Institute and UPMC Hillman Cancer Center.
“Understanding the underlying biology of how ovarian cancer forms is critical to improving outcomes for our patients.”
HGSOC begins in the fallopian tubes when healthy epithelial cells transform into precursor lesions known as serous tubal intraepithelial carcinoma (STIC). Similar to how precancerous colon polyps can become colorectal cancer, STIC lesions often develop into HGSOC tumours.
But why do healthy cells become STIC? To find out, Coffman and her team turned to the stroma, the non-cancerous connective tissue that helps cancer grow.
“Most researchers have been focused on the epithelial cells that turn into these STIC lesions and eventually into cancer,” said Coffman. “Until now, no one has really looked at the surrounding stromal microenvironment of these lesions.”
In the stroma of ovarian cancer, a type of progenitor cell normally involved in growth and repair of healthy tissue, mesenchymal stem cells (MSCs), become reprogrammed by tumour cells to support cancer growth. Coffman started by asking when these cancer-associated MSCs form and how early they play a role in cancer formation.
When she and her team profiled MSCs in the fallopian tubes of patients who did not have cancer, they were surprised to find cells that looked like cancer-associated MSCs in these healthy women.
These cells, which the researchers named high-risk MSCs, were more common in women with higher risk of ovarian cancer, those of older age or with mutations in the BRCA gene, suggesting that they play a role in cancer initiation.
When the researchers introduced these high-risk MSCs into organoids, or mini organs, derived from patient fallopian tube tissue, healthy epithelial cells transformed into cancerous cells.
“High-risk MSCs promote DNA damage in epithelial cells and then help those mutated cells survive,” explained Coffman.
“It’s the perfect storm for cancer initiation.”
High-risk MSCs also promoted tumour cell growth and increased resistance to a chemotherapy drug.
In search of a mechanism for why high-risk MSCs drive ovarian cancer, the researchers found that these cells have loss of an antioxidant called AMP kinase. Lower levels of AMP kinase led to higher levels of a protein called WT1, which in turn drove formation of compounds that cause DNA damage.
“This is the first report that stromal changes in the fallopian tube actually have a causative role in ovarian cancer initiation,” said Coffman.
“It also points to a path where we might be able to intervene.”
For example, already existing drugs that upregulate AMP kinase could potentially prevent or reverse early changes in the stroma that lead to ovarian cancer.
The findings could also inform approaches for early detection, which are sorely lacking for ovarian cancer. According to Coffman, compounds secreted by high-risk MSCs that are detectable in the bloodstream could act as biomarkers for early-stage ovarian cancer.
Diagnosis
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Diagnosis
FDA delays ruling on ‘game-changer’ breast cancer drug

The FDA has delayed approval of camizestrant while it reviews new analyses submitted by AstraZeneca after advisers voted against the breast cancer drug.
The US regulator had been considering whether to approve the oral treatment after a phase 3 switching study in a specific group of breast cancer patients.
Camizestrant is an oral SERD, or selective oestrogen receptor degrader. These drugs are designed to block and break down oestrogen receptors that can help some breast cancers grow.
AstraZeneca filed for approval based on the phase 3 Serena-6 trial, which tested a treatment-switching approach.
Patients in the study received an aromatase inhibitor and a CDK4/6 inhibitor. Aromatase inhibitors lower oestrogen levels, while CDK4/6 inhibitors are targeted cancer drugs that help slow cancer cell growth.
After detecting an ESR1 mutation, investigators switched the aromatase inhibitor to camizestrant.
An ESR1 mutation is a change in a gene linked to the oestrogen receptor. It can make some breast cancers less responsive to standard hormone treatments.
AstraZeneca said switching to camizestrant was linked to a 56 per cent increase in progression-free survival.
Progression-free survival measures how long a patient lives without their disease getting worse.
However, the FDA raised questions about the study design.
An FDA advisory committee later voted six to three that AstraZeneca had failed to show camizestrant provides a clinically meaningful benefit.
The vote was a setback for the company’s hopes of approval, although the FDA can go against advisory committee recommendations.
After the setback, AstraZeneca submitted additional analyses requested by the FDA.
The company said the analyses include data on circulating tumour DNA clearance linked to longer-term efficacy outcomes.
Circulating tumour DNA refers to fragments of genetic material from cancer cells that can be found in the blood.
AstraZeneca is expected to share the data next week at the American Society of Clinical Oncology annual meeting.
The FDA has now delayed its ruling while it reviews the additional information. AstraZeneca did not provide a new decision date.
Three-month delays are typical and, during the second Trump administration, have been common.
After budget cuts reduced its workforce, the FDA delayed rulings on assets including Bayer’s Lynkuet, Biohaven’s troriluzole and Sanofi’s tolebrutinib. The FDA reportedly blamed a “heavy workload and limited resources” for one delay.
The agency has continued to delay rulings this year, with Biogen, Savara and Travere Therapeutics among the companies to say the FDA has extended reviews of their drugs.
Like AstraZeneca, those three companies faced delays after submitting additional information that the agency needed time to review.
If the additional analyses address the regulator’s concerns, AstraZeneca could still secure approval for a drug it has estimated could generate peak sales of more than US$5bn.
Guggenheim Securities analysts recently described the Serena-6 study as “a limited commercial opportunity in our and [AstraZeneca’s] view”.
AstraZeneca is also running two adjuvant studies and a trial in a first-line setting as it seeks to position camizestrant across different stages of breast cancer care.
Adjuvant treatment is given after primary treatment, such as surgery, to reduce the risk of cancer returning. First-line treatment is the first therapy given for a disease.
Roche reported the failure of its rival oral SERD in first-line breast cancer in March, but AstraZeneca executives have argued that their trial designs and drug candidate are different.
Last week, Europe’s Committee for Medicinal Products for Human Use issued a positive opinion on camizestrant.
The drug is expected to be marketed as Etcamah in Europe.
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