By Puyaan Singh

Sept 19 (Reuters) - Regeneron said on Friday

its experimental therapy showed either a complete or partial

disappearance of a precancerous disorder, which manifests into

blood cancer, in all patients in a mid-stage trial.

The bispecific antibody therapy, Lynozyfic, showed a 100%

overall response rate in a study with 24 patients with high-risk

smoldering multiple myeloma. The data was presented at the

annual meeting of the International Myeloma Society in Toronto.

SMM is a disorder characterized by abnormal plasma cells in

the bone marrow and an abnormal protein in the blood, but

without the symptoms or organ damage of active multiple myeloma,

a type of blood cancer. The disorder can progress into multiple

myeloma.

Regeneron estimates that there are around 4,900 new SMM

cases in the United States annually, with its high-risk form

accounting for about 1,300 to 1,600 of those cases.

In the first part of the study the disease disappeared

completely in 83.3% of patients after over a year of treatment.

In total, 36.8% of patients saw a complete response, however

with a median of 3.9 months of treatment.

"We know that (responses) will deepen over time," said

Andres Sirulnik, Regeneron's clinical development head for

hematology.

Earlier this year, Lynozyfic was approved for patients with

multiple myeloma that has recurred, and who had received at

least four other therapies earlier.

Sirulnik said testing the therapy in earlier lines of

treatment such as in the SMM trial is based on a hypothesis that

"we potentially start talking about not just treating cancer,

but potentially changing the treatment paradigm in curing a

percentage of those patients."

Currently there are no approved treatments for the disease

in the U.S. Earlier this year, the U.S. Food and Drug

Administration's Oncologic Drugs Advisory Committee voted in

favor of Johnson & Johnson's ( JNJ ) Darzalex Faspro for the

treatment of SMM, indicating a potential approval.