Pioglitazone: are rumours of its death exaggerated?

Pioglitazone, Bladder Cancer and the Presumption of Innocence

BACKGROUND

Thiazolidinediones are potent exogenous agonists of PPAR-γ, which augment the effects of insulin to its cellular targets and mainly at the level of adipose tissue. Pioglitazone, the main thiazolidinedione in clinical practice, has shown cardiovascular and renal benefits in patients with type 2 diabetes, durable reduction of glycated hemoglobulin levels, important improvements of several components of the metabolic syndrome and beneficial effects of non-alcoholic fatty liver disease.

OBJECTIVE

Despite all of its established advantages, the controversy for an increased risk of developing bladder cancer, combined with the advent of newer drug classes that achieved major cardiorenal effects have significantly limited its use spreading a persistent shadow of doubt for its future role.

METHODS

Pubmed, Google and Scope databases have been thoroughly searched and relevant studies were selected.

RESULTS

This paper explores thoroughly both in vitro and in vivo (animal models and humans) studies that investigated the possible association of pioglitazone with bladder cancer.

CONCLUSION

Currently the association of pioglitazone with bladder cancer cannot be based on solid evidence. This evidence cannot justify its low clinical administration, especially in the present era of individualised treatment strategies. Definite clarification of this issue is imperative and urgently anticipated from future high quality and rigorous pharmacoepidemiologic research, keeping in mind its unique mechanism of action and its significant pleiotropic effects.

Canagliflozin, dapagliflozin and empagliflozin monotherapy for treating type 2 diabetes: systematic review and economic evaluation

BACKGROUND

Most people with type 2 diabetes are overweight, so initial treatment is aimed at reducing weight and increasing physical activity. Even modest weight loss can improve control of blood glucose. If drug treatment is necessary, the drug of first choice is metformin. However, some people cannot tolerate metformin, which causes diarrhoea in about 10%, and it cannot be used in people with renal impairment. This review appraises three of the newest class of drugs for monotherapy when metformin cannot be used, the sodium-glucose co-transporter 2 (SGLT2) inhibitors.

OBJECTIVE

To review the clinical effectiveness and cost-effectiveness of dapagliflozin (Farxiga, Bristol-Myers Squibb, Luton, UK), canagliflozin (Invokana, Janssen, High Wycombe, UK) and empagliflozin (Jardiance, Merck & Co., Darmstadt, Germany), in monotherapy in people who cannot take metformin.

SOURCES

MEDLINE (1946 to February 2015) and EMBASE (1974 to February 2015) for randomised controlled trials lasting 24 weeks or more. For adverse events, a wider range of studies was used. Three manufacturers provided submissions.

METHODS

Systematic review and economic evaluation. A network meta-analysis was carried out involving the three SGLT2 inhibitors and key comparators. Critical appraisal of submissions from three manufacturers.

RESULTS

We included three trials of dapagliflozin and two each for canagliflozin and empagliflozin. The trials were of good quality. The canagliflozin and dapagliflozin trials compared them with placebo, but the two empagliflozin trials included active comparators. All three drugs were shown to be effective in improving glycaemic control, promoting weight loss and lowering blood pressure (BP).

LIMITATIONS

There were no head-to-head trials of the different flozins, and no long-term data on cardiovascular outcomes in this group of patients. Most trials were against placebo. The trials were done in patient groups that were not always comparable, for example in baseline glycated haemoglobin or body mass index. Data on elderly patients were lacking.

CONCLUSIONS

Dapagliflozin, canagliflozin and empagliflozin are effective in improving glycaemic control, with added benefits of some reductions in BP and weight. Adverse effects are urinary and genital tract infections in a small proportion of users. In monotherapy, the three drugs do not appear cost-effective compared with gliclazide or pioglitazone, but may be competitive against sitagliptin (Januvia, Boehringer Ingelheim, Bracknell, UK).

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

An updated meta-analysis of pioglitazone exposure and bladder cancer and comparison to the drug's effect on cardiovascular disease and non-alcoholic steatohepatitis

AIM

We performed a meta-analysis of epidemiological studies evaluating exposure to pioglitazone and the risk for bladder cancer and compared these results to the drug's effects on cardiovascular disease (CVD) and non-alcoholic steatohepatitis (NASH).

METHODS

Pubmed and Embase were searched for cohort and case control studies for all years through 2016.

RESULTS

Data from 17 papers were analyzed. In cohort studies, 822 of 357,888 pioglitazone-exposed patients (0.23%) developed bladder cancer while 7691 of 2,898,682 unexposed (0.26%) did. In case control studies, 3219 of 1,146,916 patients (0.28%) developed bladder cancer. A random effects model showed no significant association between ever vs never use or with cumulative doses of pioglitazone. However, there was a significant association with 1-2 years (HR = 1.28 [1.08-1.55]) and >2 years (HR = 1.42 [1.14-1.77]) of exposure. The numbers needed to treat for one additional case of bladder cancer ranged from 899 to 6380 while to benefit CVD and NASH, 4-256 and 2-12, respectively.

CONCLUSIONS

Given the very small prevalence of bladder cancer in diabetic patients exposed (or not) to pioglitazone (<0.3%) and the much greater beneficial effects of the drug on CVD and NASH, the use of pioglitazone should be resurrected.

Pioglitazone use and risk of bladder cancer: population based cohort study

OBJECTIVE

To determine whether pioglitazone compared with other antidiabetic drugs is associated with an increased risk of bladder cancer in people with type 2 diabetes.

DESIGN

Population based cohort study.

SETTING

General practices contributing data to the United Kingdom Clinical Practice Research Datalink.

PARTICIPANTS

A cohort of 145,806 patients newly treated with antidiabetic drugs between 1 January 2000 and 31 July 2013, with follow-up until 31 July 2014.

MAIN OUTCOME MEASURES

The use of pioglitazone was treated as a time varying variable, with use lagged by one year for latency purposes. Cox proportional hazards models were used to estimate adjusted hazard ratios with 95% confidence intervals of incident bladder cancer associated with pioglitazone overall and by both cumulative duration of use and cumulative dose. Similar analyses were conducted for rosiglitazone, a thiazolidinedione not previously associated with an increased risk of bladder cancer.

RESULTS

The cohort generated 689,616 person years of follow-up, during which 622 patients were newly diagnosed as having bladder cancer (crude incidence 90.2 per 100,000 person years). Compared with other antidiabetic drugs, pioglitazone was associated with an increased risk of bladder cancer (121.0 v 88.9 per 100,000 person years; hazard ratio 1.63, 95% confidence interval 1.22 to 2.19). Conversely, rosiglitazone was not associated with an increased risk of bladder cancer (86.2 v 88.9 per 100,000 person years; 1.10, 0.83 to 1.47). Duration-response and dose-response relations were observed for pioglitazone but not for rosiglitazone.

CONCLUSION

The results of this large population based study indicate that pioglitazone is associated with an increased risk of bladder cancer. The absence of an association with rosiglitazone suggests that the increased risk is drug specific and not a class effect.