Plus Therapeutics begins Part B of Phase 1/2a trial for leptomenin metastase

Plus Therapeutics announced treatment of the first patient in Part B of the ReSPECT-LM Phase 1/2a dose escalation clinical trial of rhenium obisbemeda for the treatment of leptomeningeal metastases – LM – from solid tumors. The maximum total radiation activity administered in Phase 1/Part A was 26.4 mCi. In Phase 1/Part B the maximum administered total radiation activity will be 110.0 mCi in cohort 7. The findings in the Phase 1/Part A showed: ten patients were treated with a maximum absorbed dose of 85 Gray and up to 26.4 mCi of radiation activity; no dose limiting toxicities have been observed and a maximum tolerated dose or maximum feasible dose has not been reached in Part A; cerebrospinal fluid tumor cell counts, evaluated using a molecular diagnostic assay, decreased an average of 53% measured at 28 days post-treatment; in addition, five of the 10 treated patients in Part A remain alive with a median overall survival of 10 months.The FDA has granted Fast Track designation to rhenium obisbemeda for the treatment of LM. The ReSPECT-LM clinical trial is funded, in part, by a 3-year, $17.6M grant by the Cancer Prevention & Research Institute of Texas. LM is a rare complication of cancer in which the primary cancer spreads to the cerebrospinal fluid and leptomeninges surrounding the brain and spinal cord. The incidence of LM is on the rise, partly because cancer patients are living longer and partly because many standard chemotherapies cannot reach sufficient concentrations in the spinal fluid to kill the tumor cells, yet there are no FDA-approved therapies specifically for LM patients.