Antiacid medicines (i.e., proton pump inhibitors, H2 histamine receptor blockers, antacids) are among the most commonly prescribed and used ones. These medicines are involved in pharmacokinetic and pharmacodynamic drug-drug interactions, which is especially important in the case of drugs with a narrow therapeutic window, such as systemic cancer treatments.
This systematic review summarizes studies that investigated the association between the use of antiacids and outcomes of systemic cancer treatment in patients with advanced solid tumours. The review was conducted according to the PRISMA guideline for systematic reviews. Based on inclusion and exclusion criteria, 48 analyses were included, involving patients treated with immunotherapy (19 analyses), targeted therapies (18 analyses), and chemotherapy (11 analyses). General data and effectiveness outcomes, namely overall survival, progression-free survival and objective response rate, were collected.
Most of the included analyses were retrospective observational analyses (31/48, 65 %), with most involving patients with non-small cell lung cancer (18/48, 38 %). Among the investigated anti-acids, proton pump inhibitors predominated (33/48, 69 %), and definitions of concurrent treatment varied widely, making comparisons between findings challenging.
Antiacids were most prominently associated with worse outcomes in the case of treatment with immune checkpoint inhibitors, specifically with shorter overall survival (9/17, 53 %), shorter time to disease progression (8/16, 50 %), and poorer objective response rates (5/11, 45 %). Concurrent treatment with antiacids was also associated with poorer outcomes in targeted therapy in some analyses, particularly with shorter overall survival in nearly half of cases (4/9, 44 %), in all of these 4 analyses patients received different tyrosine kinase inhibitors. Analyses involving cytostatics yielded the most diverse results. In half of the analyses (2/4, 50 %) that included capecitabine as the only oral cytostatic agent alongside other cytostatics, patients had poorer outcomes.
Concurrent treatment with anti-acids may worsen outcomes of certain systemic cancer treatments. These results demand the careful evaluation of the potential risks and benefits of introducing a new drug, even in those with a favourable toxicity profile as in the case of antiacid medicines.
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