Selective modulation of T-cell responses in autoimmunity and cancer

Assessment of malignancy risk in patients with multiple sclerosis treated with intramuscular interferon beta-1a: retrospective evaluation using a health insurance claims database and postmarketing surveillance data

Background

Intramuscular interferon beta-1a (IFNβ-1a), a multiple sclerosis (MS) therapy that has been commercially available for over a decade, provides a unique opportunity to retrospectively assess postmarketing data for evidence of malignancy risk, compared with relatively limited data available for more recently approved therapies. Postmarketing and claims data were analyzed to determine the risk of malignancy in MS patients treated with intramuscular IFNβ-1a.

Materials and methods

The cumulative reporting rates of suspected adverse drug reactions coded to malignancy in the intramuscular IFNβ-1a global safety database were compared with malignancy incidence rates in the World Health Organization GLOBOCAN database. In addition, using data from a large US claims database, the cumulative prevalence of malignancy in MS patients treated with intramuscular IFNβ-1a was compared with non-MS population controls, MS patients without intramuscular IFNβ-1a use, and untreated MS patients. Mean follow-up was approximately 3 years for all groups, ie, 3.1 years for the intramuscular IFNβ-1a group (range 0.02–6.0 years), 2.6 years for non-MS population controls (range 0–6.0 years), 2.6 years for the intramuscular IFNβ-1a nonuse group (range 0.01–6.0 years), and 2.4 years for the untreated MS group (range 0.01–6.0 years).

Results

An estimated 402,250 patients received intramuscular IFNβ-1a during the postmarketing period. Cumulative reporting rates of malignancy in this population were consistent with GLOBOCAN incidence rates observed within the general population. The claims database included 12,894 MS patients who received intramuscular IFNβ-1a. No significant difference in malignancy prevalence was observed in intramuscular IFNβ-1a users compared with other groups.

Conclusion

Results from this evaluation provide no evidence of an increased risk of malignancy with intramuscular IFNβ-1a use.

Cancer incidence in multiple sclerosis and effects of immunomodulatory treatments

Multiple sclerosis (MS) has been linked to reduced rates of cancer prior to the era of immunomodulating treatments. We assessed the incidence of cancer in a cohort of 1338 MS patients and evaluated the effect of exposure to immunomodulatory treatment. Cancer incidence in the MS population was compared with the expected age- and gender-matched incidence rates in the Israeli population for the period 1960-2003. Time-dependant Cox model analysis was used to estimate hazard ratios for glatiramer acetate, beta-interferons (1a and 1-b) and intravenous immunoglobulins (IVIg). Among 892 female MS patients, 15 (1.7%) developed breast cancer, and 31 (3.5%) developed cancers of any type. Seventeen of 446 (3.8%) male MS patients developed cancer. The standardized incidence ratios (SIRs) computed until the time of first immunomodulatory treatment were 0.60 (95% CI, 0.38-0.92, p = 0.02) for all female cancer, and 1.11 (95% CI, 0.64-1.91) for all male cancer. Time-dependent covariate analyses for female breast cancer yielded a relative risk for glatiramer acetate of 3.10 (95% CI, 0.86-11.1) and 0.52 (95% CI, 0.07-4.05) for beta-interferons. For IVIg, the analyses were uninformative. Our findings indicate that cancer incidence is significantly lower in female MS patients than in the general population. Female MS patients treated with glatiramer acetate showed an elevated rate of breast cancer and all MS patients treated with beta-interferons showed an elevated risk of non-breast cancers though not statistically significant (p = 0.122 and 0.072, respectively). Further study is needed to assess possible associations between long-term exposure to the novel immunomodulatory treatments in MS and rate of cancer.