Efficacy of hydroxychloroquine in the prevention of thromboembolic events: A systematic review and meta-analysis

OBJECTIVE

To estimate the risk ratio (RR) of thromboembolic events in chloroquine and hydroxychloroquine users compared to non-users.

METHODS

We systematically reviewed randomized controlled trials (RCTs), using MEDLINE and EMBASE databases from inception to the present, reporting thromboembolic events in chloroquine and hydroxychloroquine users compared to non-users. Four authors independently screened all the records obtained through our search strategy and later revised the selected full-text articles for eligibility, according to our inclusion criteria. The same four authors independently extracted relevant data through a customized data collection form while two other authors assessed the quality of the included RCTs using the Cochrane risk-of-bias tool (Version 2.0). All the disagreements were resolved through discussions among the authors. We calculated the risk ratio (RR) and its respective standard error of developing thromboembolic events in hydroxychloroquine users and non-users for each individual study and pooled the results using a random effects model meta-analysis. We assessed Heterogeneity using the Tau² and I², and publication bias using funnel plotting and Egger's regression. The protocol for this systematic review is registered at the PROSPERO database (CRD42021247902).

RESULTS

Thirteen RCTs met our eligibility criteria and were included in our analysis (2663 patients). We found that hydroxychloroquine-no study on chloroquine was found-reduced the risk of thromboembolic events by 49% (RR 0.51[IC 95% 0.31-0.84]) with a medium heterogeneity (I² = 67% and T² = 0.4948). We did find some asymmetry in the inspection of the funnel plot, which was ruled out through an Egger's regression (p-value = 0.1025).

CONCLUSION

Our data reinforce the idea that hydroxychloroquine reduces the risk of thromboembolic events.

Safety of treatment with chloroquine and hydroxychloroquine: A ten-year systematic review and meta-analysis

OBJECTIVE

To estimate the incidence rate ratio (IRR) of adverse events (AE) in chloroquine or hydroxychloroquine users.

METHODS

We systematically reviewed randomized controlled trials (RCTs), using MEDLINE (2010-2020) and EMBASE (2010-2020) databases, reporting AE in chloroquine or hydroxychloroquine users during treatment for lupus, rheumatoid arthritis, malaria and COVID-19. The protocol for this systematic review is registered at the PROSPERO database (CRD42020197938). The quality of the included studies was assessed using the Cochrane risk-of-Bias tool and relevant data were extracted though a customized data collection form, independently, by two authors. The IRR of AE was estimated using a random-effect model meta-analysis and heterogeneity was evaluated by T² and I². Subgroup analysis was performed, and publication bias was assessed by funnel-plot.

RESULTS

Forty-six RCTs met our eligibility criteria and were included in our analysis (23132 patients). There was not a single death attributed to chloroquine or hydroxychloroquine use in the included RCTs. The IRR of general AE during antimalarial use was 1.15 [CI 95% 1.01-1.31]. COVID-19 patients treated with either antimalarial presented an 83% and 165% higher risk of developing general and gastrointestinal AE, respectively, in comparison with controls. The use of antimalarial increased the risk of developing dermatological AE by 92% in malarial studies and reduced by 65% in lupus studies. We did not find a significatively higher risk of cardiovascular nor ophthalmological AE in antimalarial users.

CONCLUSIONS

Our data reinforces that chloroquine and hydroxychloroquine have a good safety profile though caution is advised when using higher than usual doses in hospitalized COVID-19 patients.

Hydroxychloroquine in rheumatic autoimmune disorders and beyond

Initially used as antimalarial drugs, hydroxychloroquine (HCQ) and, to a lesser extent, chloroquine (CQ) are currently being used to treat several diseases. Due to its cost‐effectiveness, safety and efficacy, HCQ is especially used in rheumatic autoimmune disorders (RADs), such as systemic lupus erythematosus, primary Sjögren's syndrome and rheumatoid arthritis. Despite this widespread use in the clinic, HCQ molecular modes of action are still not completely understood. By influencing several cellular pathways through different mechanisms, CQ and HCQ inhibit multiple endolysosomal functions, including autophagy, as well as endosomal Toll‐like receptor activation and calcium signalling. These effects alter several aspects of the immune system with the synergistic consequence of reducing pro‐inflammatory cytokine production and release, one of the most marked symptoms of RADs. Here, we review the current knowledge on the molecular modes of action of these drugs and the circumstances under which they trigger side effects. This is of particular importance as the therapeutic use of HCQ is expanding beyond the treatment of malaria and RADs.

Autophagy inhibition enhances vorinostat-induced apoptosis via ubiquitinated protein accumulation

Autophagy is an evolutionarily conserved cell survival pathway that enables cells to recoup ATP and other critical biosynthetic molecules during nutrient deprivation or exposure to hypoxia, which are hallmarks of the tumour microenvironment. Autophagy has been implicated as a potential mechanism of resistance to anticancer agents as it can promote cell survival in the face of stress induced by chemotherapeutic agents by breaking down cellular components to generate alternative sources of energy. Disruption of autophagy with chloroquine (CQ) induces the accumulation of ubiquitin-conjugated proteins in a manner similar to the proteasome inhibitor bortezomib (BZ). However, CQ-induced protein accumulation occurs at a slower rate and is localized to lysosomes in contrast to BZ, which stimulates rapid buildup of ubiquitinated proteins and aggresome formation in the cytosol. The histone deacetylase (HDAC) inhibitor vorinostat (VOR) blocked BZ-induced aggresome formation, but promoted CQ-mediated ubiquitinated protein accumulation. Disruption of autophagy with CQ strongly enhanced VOR-mediated apoptosis in colon cancer cells. Accordingly, knockdown of the essential autophagy gene Atg7 also sensitized cells to VOR-induced apoptosis. Knockdown of HDAC6 greatly enhanced BZ-induced apoptosis, but only marginally sensitized cells to CQ. Subsequent studies determined that the CQ/VOR combination promoted a large increase in superoxide generation that was required for ubiquitinated protein accumulation and cell death. Finally, treatment with the CQ/VOR combination significantly reduced tumour burden and induced apoptosis in a colon cancer xenograft model. Collectively, our results establish that inhibition of autophagy with CQ induces ubiquitinated protein accumulation and VOR potentiates CQ-mediated aggregate formation, superoxide generation and apoptosis.

Lucanthone is a novel inhibitor of autophagy that induces cathepsin D-mediated apoptosis

Cellular stress induced by nutrient deprivation, hypoxia, and exposure to many chemotherapeutic agents activates an evolutionarily conserved cell survival pathway termed autophagy. This pathway enables cancer cells to undergo self-digestion to generate ATP and other essential biosynthetic molecules to temporarily avoid cell death. Therefore, disruption of autophagy may sensitize cancer cells to cell death and augment chemotherapy-induced apoptosis. Chloroquine and its analog hydroxychloroquine are the only clinically relevant autophagy inhibitors. Because both of these agents induce ocular toxicity, novel inhibitors of autophagy with a better therapeutic index are needed. Here we demonstrate that the small molecule lucanthone inhibits autophagy, induces lysosomal membrane permeabilization, and possesses significantly more potent activity in breast cancer models compared with chloroquine. Exposure to lucanthone resulted in processing and recruitment of microtubule-associated protein 1 light chain 3 (LC3) to autophagosomes, but impaired autophagic degradation as revealed by transmission electron microscopy and the accumulation of p62/SQSTM1. Microarray analysis, qRT-PCR, and immunoblotting determined that lucanthone stimulated a large induction in cathepsin D, which correlated with cell death. Accordingly, knockdown of cathepsin D reduced lucanthone-mediated apoptosis. Subsequent studies using p53(+/+) and p53(-/-) HCT116 cells established that lucanthone induced cathepsin D expression and reduced cancer cell viability independently of p53 status. In addition, lucanthone enhanced the anticancer activity of the histone deacetylase inhibitor vorinostat. Collectively, our results demonstrate that lucanthone is a novel autophagic inhibitor that induces apoptosis via cathepsin D accumulation and enhances vorinostat-mediated cell death in breast cancer models.

New concepts in antimalarial use and mode of action in dermatology

ABSTRACT:  Although chloroquine, hydroxychloroquine and quinacrine were originally developed for the treatment of malaria, these medications have been used to treat skin disease for over 50 years. Recent clinical data have confirmed the usefulness of these medications for the treatment of lupus erythematosus. Current research has further enhanced our understanding of the pharmacologic mechanisms of action of these drugs involving inhibition of endosomal toll‐like receptor (TLR) signaling limiting B cell and dendritic cell activation. With this understanding, the use of these medications in dermatology is broadening. This article highlights the different antimalarials used within dermatology through their pharmacologic properties and mechanism of action, as well as indicating their clinical uses. In addition, contraindications, adverse effects, and possible drug interactions of antimalarials are reviewed.

Old and new drugs used in rheumatoid arthritis: a historical perspective. Part 1: the older drugs

Rheumatoid arthritis is the paradigmatic immune-mediated inflammatory arthropathy and may be of comparatively recent, New World origin. Apart from the symptom-relieving nonsteroidal anti-inflammatory drugs, whose natural congeners have been in use since antiquity for musculoskeletal pain and inflammation, only a dozen drugs or drug classes--the disease-modifying antirheumatic drugs--are currently in common use in rheumatoid arthritis. Development of these drugs has been a notable achievement of the 20th century. Some were developed serendipitously (glucocorticoids, antimalarials), some were the product of faulty reasoning (gold, D-penicillamine), and others were applied for plausible reasons but whose mechanism remains unproven (sulfasalazine, methotrexate, minocycline). A minority were originally applied on the basis of actions that remain germane to the pathophysiology of rheumatoid arthritis as currently understood (azathioprine, cyclosporine, leflunomide, infliximab, etanercept). Among the latter are the more recently introduced and effective agents. The practical use of these drugs is determined by efficacy-toxicity considerations, which have also driven the recent development of the cyclooxygenase-2-selective nonsteroidal anti-inflammatory drugs.