Importance of benefit-to-risk assessment for disease-modifying drugs used to treat MS

Benefit-Risk of Therapies for Relapsing-Remitting Multiple Sclerosis: Testing the Number Needed to Treat to Benefit (NNTB), Number Needed to Treat to Harm (NNTH) and the Likelihood to be Helped or Harmed (LHH): A Systematic Review and Meta-Analysis

OBJECTIVE

This study aimed to test the number needed to treat to benefit (NNTB) and to harm (NNTH), and the likelihood to be helped or harmed (LHH) when assessing benefits, risks, and benefit-risk ratios of disease-modifying treatments (DMTs) approved for relapsing-remitting multiple sclerosis (RRMS).

METHODS

In May 2016, we conducted a systematic review using the PubMed and Cochrane Central Register of Controlled Trials databases to identify phase III, randomized controlled trials with a duration of ≥2 years that assessed first-line (dimethyl fumarate [DMF], glatiramer acetate [GA], β-interferons [IFN], and teriflunomide) or second-line (alemtuzumab, fingolimod, and natalizumab) DMTs in patients with RRMS. Meta-analyses were performed to estimate relative risks (RRs) on annualized relapse rate (ARR), proportion of relapse-free patients (PPR-F), disability progression (PP-F-CDPS3M), and safety outcomes. NNTB and NNTH values were calculated applying RRs to control event rates. LHH was calculated as NNTH/NNTB ratio.

RESULTS

The lowest NNTBs on ARR, PPR-F, and PP-F-CDPS3M were found with IFN-β-1a-SC (NNTB 3, 95 % CI 2-4; NNTB 7, 95 % CI 4-18; NNTB 4, 95 % CI 3-7, respectively) and natalizumab (NNTB 2, 95 % CI 2-3; NNTB 4, 95 % CI 3-6; NNTB 9, 95 % CI 6-19, respectively). The lowest NNTH on adverse events leading to treatment discontinuation was found with IFN-β-1b (NNTH 14, 95 % 2-426) versus placebo; a protective effect was noted with alemtuzumab versus IFN-β-1a-SC (NNTB 22, 95 % 17-41). LHHs >1 were more frequent with IFN-β-1a-SC and natalizumab.

CONCLUSIONS

These metrics may be valuable for benefit-risk assessments, as they reflect baseline risks and are easily interpreted. Before making treatment decisions, clinicians must acknowledge that a higher RR reduction with drug A as compared with drug B (versus a common comparator in trial A and trial B, respectively) does not necessarily mean that the number of patients needed to be treated for one patient to encounter one aditional outcome of interest over a defined period of time is lower with drug A than with drug B. Overall, IFN-β-1a-SC and natalizumab seem to have the most favorable benefit-risk ratios among first- and second-line DMTs, respectively.

Integration of PKPD relationships into benefit-risk analysis

AIM

Despite the continuous endeavour to achieve high standards in medical care through effectiveness measures, a quantitative framework for the assessment of the benefit-risk balance of new medicines is lacking prior to regulatory approval. The aim of this short review is to summarise the approaches currently available for benefit-risk assessment. In addition, we propose the use of pharmacokinetic-pharmacodynamic (PKPD) modelling as the pharmacological basis for evidence synthesis and evaluation of novel therapeutic agents.

METHODS

A comprehensive literature search has been performed using MESH terms in PubMed, in which articles describing benefit-risk assessment and modelling and simulation were identified. In parallel, a critical review of multi-criteria decision analysis (MCDA) is presented as a tool for characterising a drug's safety and efficacy profile.

RESULTS

A definition of benefits and risks has been proposed by the European Medicines Agency (EMA), in which qualitative and quantitative elements are included. However, in spite of the value of MCDA as a quantitative method, decisions about benefit-risk balance continue to rely on subjective expert opinion. By contrast, a model-informed approach offers the opportunity for a more comprehensive evaluation of benefit-risk balance before extensive evidence is generated in clinical practice.

CONCLUSIONS

Benefit-risk balance should be an integral part of the risk management plan and as such considered before marketing authorisation. Modelling and simulation can be incorporated into MCDA to support the evidence synthesis as well evidence generation taking into account the underlying correlations between favourable and unfavourable effects. In addition, it represents a valuable tool for the optimization of protocol design in effectiveness trials.

Biologics in the Treatment of Psoriasis: Clinical and Economic Overview

Background:

The use of biologic medications for psoriasis is a recent therapeutic advance.

Objective:

To review clinical and economic data for biologic therapies in the treatment of chronic plaque psoriasis.

Methods:

Published meta-analyses and additional literature review identified randomized controlled trials. Analyses included the number needed to treat (NNT), the cost in Canadian dollars for the first year of treatment per the Canadian product monograph, and the estimated cost per responder achieving a 75% reduction in Psoriasis Area and Severity Index score (PASI 75).

Results:

Pooled NNTs were 1.3 (infliximab), 1.5 (ustekinumab 90 mg), 1.6 (adalimumab and ustekinumab 45 mg), 2.3 (etanercept), 4.1 (efalizumab), and 5.6 (alefacept). The annual treatment cost per patient was $19,825 to $37,600. The cost per patient achieving a PASI 75 response at 12 weeks ranged from $8,330 (adalimumab) to $71,371 (alefacept).

Conclusion:

This analysis suggests favorable cost and benefits of biologic psoriasis therapies, particularly adalimumab, infliximab, and ustekinumab.

High-dose, high-frequency recombinant interferon beta-1a in the treatment of multiple sclerosis

BACKGROUND

There is at present no cure for multiple sclerosis (MS), and existing therapies are designed primarily to prevent lesion formation, decrease the rate and severity of relapses and delay the resulting disability by reducing levels of inflammation.

OBJECTIVE

The aim of this review was to assess the treatment of relapsing MS with particular focus on subcutaneous (s.c.) interferon (IFN) beta-1a.

METHOD

The literature on IFN beta-1a therapy of MS was reviewed based on a PubMed search (English-language publications from 1990) including its pharmacodynamics and pharmacokinetics, clinical efficacy in relapsing MS as shown in placebo-controlled studies and in comparative trials, efficacy in secondary progressive MS, safety and tolerability, and the impact of neutralizing antibodies.

CONCLUSION

The literature suggests that high-dose, high-frequency s.c. IFN beta-1a offers an effective option for treating patients with relapsing MS, with proven long-term safety and tolerability, and has a favourable benefit-to-risk ratio compared with other forms of IFN beta.

Comparison of subcutaneous interferon beta-1a with glatiramer acetate in patients with relapsing multiple sclerosis (the REbif vs Glatiramer Acetate in Relapsing MS Disease [REGARD] study): a multicentre, randomised, parallel, open-label trial

BACKGROUND

Interferon beta-1a and glatiramer acetate are commonly prescribed for relapsing-remitting multiple sclerosis (RRMS), but no published randomised trials have directly compared these two drugs. Our aim in the REGARD (REbif vs Glatiramer Acetate in Relapsing MS Disease) study was to compare interferon beta-1a with glatiramer acetate in patients with RRMS.

METHODS

In this multicentre, randomised, comparative, parallel-group, open-label study, patients with RRMS diagnosed with the McDonald criteria who had had at least one relapse within the previous 12 months were randomised to receive 44 mug subcutaneous interferon beta-1a three times per week or 20 mg subcutaneous glatiramer acetate once per day for 96 weeks to assess the time to first relapse. A subpopulation of 460 patients (230 from each group) also had serial MRI scans to assess T2-weighted and gadolinium-enhancing lesion number and volume. Treatments were assigned by a computer-generated randomisation list that was stratified by centre. Analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00078338.

FINDINGS

Between February and December, 2004, 764 patients were randomly assigned: 386 to interferon beta-1a and 378 to glatiramer acetate. After 96 weeks, there was no significant difference between groups in time to first relapse (hazard ratio 0.94, 95% CI 0.74 to 1.21; p=0.64). Relapse rates were lower than expected: 258 patients (126 in the interferon beta-1a group and 132 in the glatiramer acetate group) had one or more relapses (the expected number was 460). For secondary outcomes, there were no significant differences for the number and change in volume of T2 active lesions or for the change in the volume of gadolinium-enhancing lesions, although patients treated with interferon beta-1a had significantly fewer gadolinium-enhancing lesions (0.24 vs 0.41 lesions per patient per scan, 95% CI -0.4 to 0.1; p=0.0002). Safety and tolerability profiles were consistent with the known profiles for both compounds. The overall number and severity of adverse events were similar between the treatments and were not an important cause for discontinuation of the trial during the 96 weeks.

INTERPRETATION

There was no significant difference between interferon beta-1a and glatiramer acetate in the primary outcome. The ability to predict clinical superiority on the basis of results from previous studies might be limited by a trial population with low disease activity, which is an important consideration for ongoing and future trials in patients with RRMS.

The potential role for cladribine in the treatment of multiple sclerosis: clinical experience and development of an oral tablet formulation

BACKGROUND

Disease-modifying drugs available for multiple sclerosis (MS) require chronic, regular, parenteral administration. Effective oral MS therapies may improve long-term adherence. A number of oral therapies are in development, including cladribine--a preferential lymphocyte-depleting therapy with a well-established safety profile across other indications.

OBJECTIVE

To review information available on the safety and efficacy of cladribine in the treatment of MS, in the context of the ongoing development of an oral tablet formulation.

METHODS

An electronic search was performed to identify publications in which 'cladribine' was listed as a major index term. Results of the literature search were supplemented by other relevant secondary references and publications.

FINDINGS

The majority of published data on cladribine describe its use in diseases other than MS. However, three major, industry-sponsored, double-blind, placebo-controlled trials of parenteral cladribine were identified, involving 262 patients with relapsing or progressive forms of MS. Patients received cumulative doses of 0.7-2.8 mg/kg of cladribine over 4-6 months and were followed-up for at least 6-12 months thereafter. Individual results of these studies of parenteral cladribine indicate that it can reduce: (i) the number and volume of T1 gadolinium-enhancing lesions; (ii) the accumulation of T2 lesion volume; (iii) relapse rate; and (iv) disability progression. A dose-dependent increase in adverse events was observed, leading to selection of low doses for use in an ongoing clinical development program of an oral tablet formulation. Efficacy and safety data from four independent studies/case reports have also supported the potential benefits of cladribine in MS. While parenteral cladribine (at doses of 0.7-2.1 mg/kg) is associated with a good short-term safety and tolerability profile, additional long-term data are required--and the safety profile of the oral tablet formulation is yet to be established. To this end, the efficacy and safety of oral cladribine tablets are now being assessed as monotherapy and add-on therapy to interferon-beta-1a in two, 96-week, double-blind clinical trials of relapsing forms of MS. These ongoing studies will utilize newer diagnostic criteria and more sensitive evaluation techniques than were available at the time of the parenteral studies of cladribine.

CONCLUSION

Preliminary data indicate that cladribine is effective for the treatment of MS and has a promising safety and tolerability profile. The sustained immunologic effects of cladribine make it suitable for intermittent oral dosing, which is expected to offer benefits for patient satisfaction and therapeutic adherence.

Integrating an evidence-based assessment of benefit and risk in disease-modifying treatment of multiple sclerosis

BACKGROUND

As results from an increasing number of clinical trials with disease-modifying drugs (DMDs) in multiple sclerosis (MS) become available, the challenge for the treating neurologist is how to decide on the appropriate therapy for an individual patient.

OBJECTIVE

An International Working Group for Treatment Optimization in MS met to consider how the principles of evidence-based medicine (EBM) should be used to assess the current best evidence regarding the treatment of MS. This report summarizes the outcome from the workshop at which this topic was addressed.

RESULTS

Class I evidence from head-to-head studies provides the best tool for direct comparisons of DMDs. However, other EBM approaches to data analysis from placebo-controlled trials can be used to help determine the benefits and risks of a particular DMD relative to placebo by calculating the number needed to treat to achieve a positive outcome, such as avoiding a relapse, and the number needed to harm to produce an additional adverse event, such as having a therapy-related dropout. This provides a structured basis for comparisons between DMDs.

CONCLUSION

While such comparisons have their limitations, particularly when drugs with substantially different side-effect profiles are to be compared, they can provide useful information to guide treatment decisions.