Effect of Loratadine in Lymphangioleiomyomatosis

Overview

INTRODUCTION: LAM is a rare and lethal disease characterized by progressive cystic lung destruction. Inhibition of mTOR with rapamycin is the current standard of care (SOC), which can slow-down disease. Plasma major histamine metabolite (Methylimidazoleacetic acid \[MIAA\]) is increased in LAM. Loratadine is a histamine receptor antagonist (HR1), which inhibits LAM cell proliferation. Therefore, a novel phase-II clinical trial for assessing safety and potential benefits of loratadine in LAM has been initiated. METHODS: LORALAM clinical trial, phase-II, double-blind, randomized, placebo controlled, parallel-group, multicentre study initiates recruitment in July 2020. Enrollment plan includes 62 subjects with LAM on treatment with rapamycin ≥3 months, randomized 1:1 to add oral loratadine 10mg/day or placebo, once daily, for 52 weeks. Recruitment will end in June 2021. The primary endpoints are 1) to assess the safety profile of loratadine associated with rapamycin, 2) lung function decline after 52 weeks of treatment. The secondary endpoints are a) quality of life and progression free-survival time, b) changes in the established LAM serum biomarker VEGFD, c) the utility of MIAA for monitoring disease progression and biological treatment effect. ETHICS AND DISSEMINATION: The study will be carried out in accordance with Good Clinical Practice guidelines, Declaration of Helsinki principles, and each ethical committee. This clinical trial contemplates the possibility of increasing the number of centers and including patients from patient support groups (LAM foundation, AELAM)

Lymphangioleiomyomatosis (LAM) is a rare and lethal lung disease affecting almost exclusively women of childbearing age and characterized by progressive cystic lung destruction. LAM results from germline and somatic loss-of-function mutations in the tuberous sclerosis complex 1 and 2 genes (TSC1/2), and therefore diseased cells show abnormal activation of the mechanistic target of rapamycin (mTOR). Inhibition of mTOR with rapamycin (also known as sirolimus) is the current standard of care. However, this therapy does not fully kill LAM cells, shows variable tolerability and treatment answer. Therefore, sirolimus has slowed-down disease progression but young patients still need lung transplantation despite treatment. In addition, LAM diagnosis and clinical monitoring is also challenging due to the heterogeneity of symptoms and insufficiency of non-invasive tests. Here, guided by comprehensive preclinical data obtained in the context of a Spanish research network for LAM, and with the support of the national Association of LAM patients (AELAM), the investigators propose a phase-II clinical trial for assessing if the tricyclic antihistamine loratadine is effective in slowing the progression of lung disease in LAM. Loratadine is an histamine receptor 1 (HR1) antagonist, widely used for allergic process, that also acts through different intracellular signaling, including Akt/MITF and PKCBII-tyrosine kinase. Recent studies have demonstrated that co-treatment with loratadine sensitize KBV20C resistant cells to vincristine, which improve the onco-therapeutical effect. The primary study objective is to assess the safety profile of loratadine 10 mg/day associated with the current standard treatment (sirolimus) and its potential benefit abrogating the lung function decline after 52 weeks of treatment. The secondary objectives include; a) an assessment of quality of life and progression free-survival time, and, b) to determine the clinical usefulness of the major histamine-derived metabolite methylimidazoleacetic acid (MIAA) for monitoring of disease progression and biological treatment effect.