*

Oral camizestrant cut risk of breast cancer progression,

death

risk by 56%

*

Approach may offer new treatment paradigm, expert says

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Separate trial of AstraZeneca ( AZN ) immunotherapy Imfinzi shows

promise in early-stage stomach and esophageal cancers

(Adds CEO comments in paragraphs 14-15)

By Julie Steenhuysen

CHICAGO, June 1 (Reuters) - Treating breast cancer

patients with AstraZeneca's ( AZN ) experimental pill

camizestrant at the first sign of resistance to standard

therapies cut the risk of disease progression or death by half,

a finding that could be practice changing, experts said on

Sunday.

The results, presented at the American Society of Clinical

Oncology meeting in Chicago, mark the first use of a blood test

called a liquid biopsy to indicate the need for a change in

treatment in women with a common form of breast cancer, even

before tumor growth can be detected on imaging.

The early switch approach in women with hormone

receptor-positive, HER2-negative breast cancer resulted in a 56%

reduction in the risk of disease progression or death, said Dr.

Eleonora Teplinsky, an oncologist at Valley-Mount Sinai

Comprehensive Cancer Care and an ASCO breast cancer expert.

"When patients progress on scans, we're already behind,"

Teplinsky said at a media briefing. She said an early switch

approach, before disease progression, allows doctors "to

essentially stay ahead of the curve."

Camizestrant is not yet FDA-approved, but Teplinsky said she

believes the data will likely result in a new treatment

paradigm.

The trial involved 3,256 patients with advanced hormone

receptor-positive, HER2-negative breast cancer, the most common

type in which hormones such as estrogen fuel cancer growth.

These cancers lack high levels of HER2, another cancer driver.

Women in the trial had at least six months of treatment with

aromatase inhibitors that block hormones fueling the cancer, as

well as targeted drugs called CDK4/6 inhibitors such as

Novartis' Kisqali, Pfizer's ( PFE ) Ibrance or Eli

Lilly's ( LLY ) Verzenio, which block an enzyme that fuels

cancer growth.

About 40% of patients treated with aromatase inhibitors

develop mutations in the estrogen receptor 1 gene called ESR1

mutations, a sign of early drug resistance.

Camizestrant and similar drugs called selective estrogen

receptor degraders, or SERDS, block estrogen receptor signaling

in cancer cells.

In the trial, researchers used blood tests to look for ESR1

mutations until 315 patients were identified. They were randomly

assigned to either switch to camizestrant plus the CDK4/6

inhibitor or continue with standard treatment plus a placebo.

The researchers found that it took 16 months for the disease

to progress in women who got camizestrant, compared with 9.2

months in those who continued on standard therapy, a

statistically significant difference in a measure known as

progression-free survival.

No new side effects were reported and few patients from

either group dropped out due to side effects.

"This is going to be very impactful for our patients," said

Dr. Hope Rugo, head of breast medical oncology at City of Hope

in Duarte, California. The question, she said, is how do doctors

incorporate the testing into clinical practice.

THE FUTURE OF CANCER TREATMENT

AstraZeneca ( AZN ) Chief Executive Pascal Soriot in a press

briefing acknowledged that monitoring patients for drug

resistance before cancer progresses would require a switch in

practice, but said it represents the future of cancer treatment.

"It will be complicated in the beginning," he said, "but

over time, like everything else, we will manage to simplify it

and it will become part of what people do."

In a separate trial, adding AstraZeneca's ( AZN ) immunotherapy

Imfinzi to standard treatment before and after surgery in

patients with early-stage stomach and esophageal cancers helped

delay cancer progression or recurrence compared to chemotherapy

alone.

The global study of nearly 950 patients tested Imfinzi,

known chemically as durvalumab, in combination with a

chemotherapy regimen called FLOT given around the time of

initial cancer surgery.

The durvalumab plus FLOT combination led to a 29% reduction

in disease recurrence, progression or death, referred to as

event-free survival, compare with those who received the

chemotherapy regimen alone.

"We demonstrate that immunotherapy works in early-stage

disease, which is great," lead study author Dr. Yelena Janjigian

of Memorial Sloan Kettering Cancer Center in New York told

reporters at the meeting.

"We did not see any new safety signals, so this will change

practice for our patients, which is exciting to see."

Both studies were also published on Sunday in the New

England Journal of Medicine.