Mirati to focus adagrasib/Keytruda study in low PDL1 lung cancer patients (updated)

Mirati Therapeutics

06/12/2022 06:42

(Adds analyst comment, share price; clarifies details of Amgen
studies)
    By Deena Beasley
       Dec 5 (Reuters) - Early trial data shows that a
combination of Mirati Therapeutics  MRTX.O  experimental drug
adagrasib and Merck & Co's  MRK.N  immunotherapy Keytruda helped
about half of previously untreated metastatic lung cancer
patients, with manageable side effects, Mirati said on Monday.
    The company expects the largest advantage in patients with
lower levels of PDL1, the protein targeted by Keytruda, and 
plans to launch a phase-three trial enrolling only those
patients soon, Mirati chief executive officer David Meek told
Reuters.
    Wall Street analysts called the early results encouraging, 
but shares of Mirati were down more than 8% at $84.50 after
hours on Monday. More trial details will be presented on
Wednesday.
        "We believe the data continue to support the regimen's
differentiated positioning relative to standard of care and are
far more favorable than that of Lumakras plus (immunotherapy),"
JP Morgan analyst Eric Joseph said in a research note on Monday,
referring to a rival drug sold by Amgen Inc  AMGN.O . 
  
        Both drugs target a mutated form of a gene known as KRAS
that occurs in about 13% of non-small cell lung cancers (NSCLC),
the most common form of the disease.
    Mirati's phase-three trial will compare adagrasib and
Keytruda with chemotherapy plus Keytruda. The initial treatment
for patients with higher levels of PDL1 is Keytruda alone, and
Mirati will likely begin planning next year for a combination
study in those patients, Meek said.
    Recent data shows that 19% of NSCLC patients treated with
Keytruda plus chemotherapy were alive after five years, compared
with 11% of patients treated with a placebo and chemotherapy.   
    Out of seven phase-two trial patients given the adagrasib
combination, four (57%) had tumor shrinkage, and none had tumor
growth, Mirati said.
    A preliminary analysis of 53 patients showed that 49% of
them had responded to the combination treatment.
    Serious side effects occurred in 44% of patients, including
increased levels of pancreatic enzymes in 11% and higher liver
enzymes in 8% to 9%. 
    Amgen earlier this year said more study was needed after a
trial of Lumakras in combination with immunotherapies found that
high numbers of patients experienced liver toxicity.   
    Mirati expects a U.S. Food and Drug Administration decision
by Dec. 14 on its application to sell adagrasib for advanced
NSCLC patients who have stopped responding to other drugs.
    Meek declined to comment on takeover speculation that had
pushed shares of Mirati up nearly 40% since mid-November.
    "We're laser-focused on crossing the finish line with the
approval and then we have to launch the drug .... We're so busy
right now," he said.
 (Reporting by Deena Beasley in Los Angeles; Editing by Matthew
Lewis and Bradley Perrett)
 ((deena.beasley@thomsonreuters.com; 213 955 6746; Reuters
Messaging: deena.beasley.thomsonreuters.com@reuters.net))