Rheum in Review: Tocilizumab and Malignancy, Vitamin B and Hip Fracture Risk, Rituximab for RA Prevention, and More

Here are the top stories covered by DocWire News this week in the Rheumatology section. In this edition, learn the impact of biologic drugs on malignancy, why women should not take more than the recommended dose of vitamin B, the top reasons older patients discontinue arthritis medication, and rituximab’s effect on seropositive palindromic rheumatism. 

A recent study found no difference in risk of malignancy (excluding non-melanoma skin cancer) among rheumatoid arthritis (RA) patients initiating tocilizumab compared to tumor necrosis factor inhibitor (TNFi) or abatacept. Researchers collected data from Medicare, PharMetrics Plus (IMS), and Truven (MarketScan) databases on adult RA patients who recently started tocilizumab or a TNFi after failing a different TNFi, abatacept, or tofacitinib. Tocilizumab initiators were propensity-score matched 1:3 to TNFi initiators within each database. The analysis included a total of 13,102 patients starting tocilizumab treatment and 26,727 TNFi patients. Malignancy rates per 1,000 person-years varied among databases, but the rates were similar for both cohorts: the low estimates were 8.27 (IMS) in the tocilizumab group and 9.64 (MarketScan) in the TNFi group; the high rates were 23.18 (Medicare) and 21.46 (Medicare), respectively. The combined hazard ratio (HR) for all three databases for malignancy risk in tocilizumab compared to TNFi was 0.98 (95% confidence interval [CI] 0.80-1.19). A secondary analysis compared tocilizumab to abatacept and had a combined HR of 0.97 (95% CI 0.74-1.27). 

Too much of a good thing? Women who take the higher recommended daily allowance (RDA) for vitamin B6 and vitamin B12 may be heightening their risk for hip fracture. Data from the Nurses’ Health Study were gathered on 75,864 postmenopausal women. Patients completed a survey with information regarding their medical history, lifestyle, and disease risk factors. They repeated the survey every two years and were followed until May 2014. A total of 2,304 hip fractures were recorded. In adjusted analyses, compared to a reference group, the highest vitamin B6 overall intake (diet and supplements) group had a relative risk (RR) for hip fracture of 1.29 (95% CI, 1.04-1.59; P = .06 for linear trend). When comparing groups based on vitamin B6 intake from supplements only, the highest intake group’s RR was 1.41 (95% CI, 1.10-1.80; P = .09 for linear trend). Increased vitamin B12 intake was insignificantly associated with an increased risk compared to the reference group, but the risk increased linearly with the dosage. For reference, the National Institutes for Health’s RDA  for vitamin B6 is 1.5 mg for women over the age of 50, and for vitamin B12 recommendation is 2.4 μg for women aged 14 years and older. 

Patients with seropositive palindromic rheumatism (PR) experience episodes of joint pain similar to symptoms in RA, but between incidents are symptom-free. PR is a rare condition, but patients with PR frequently progress to RA. According to new findings featured in Clinical Rheumatology, PR patients may benefit from rituximab (Rituxan) if they have not responded to conventional synthetic disease-modifying antirheumatic drugs (DMARDs). PR patients (n = 33) received an initial 500 mg dose of rituximab and subsequently received more if adequate disease control was not achieved; the majority of patients (88%) were on combination DMARDs. Complete disease control was achieved in the whole cohort. Less than half of patients relapsed, and those who did achieved remission after repeat rituximab infusions. No serious adverse events occurred. No patients progressed to RA until the end of the follow-up period. 

Researchers recently questioned why RA patients aged ≥ 65 years may discontinue their biological DMARDs. They looked specifically at abatacept (ABT, n = 272), tocilizumab (TCZ, n = 234), etanercept (ETN, n = 184), golimumab (GLM, n = 159), infliximab (IFX, n = 101), adalimumab (ADA, n = 97), and certolizumab pegol (CZP, n = 51); data were gathered from the Kansai Consortium for Well-being of Rheumatic Disease Patients, which included RA patients from seven institutes in Japan. Data were included for 661 patients (1,098 biological DMARDs treatment courses). Mean age at baseline was 71.7 years, and the majority of the cohort was female. At 36 months, just over half (51.2%) of treatment courses were discontinued: lack of effectiveness, 25.1%; toxic adverse events, 11.8%; non-toxic reasons, 9.7%; and remission, 4.6%. Retention rates due to lack of effectiveness were: ABT (81.6%), TCZ (78.0%), GLM (76.5%), IFX (68.0%), ADA (67.3%), CZP (60.9%), and ETN (55.4%) (Cox P<0.001); retention rates attributed to toxic events were: ABT (95.4%), CZP (92.9%), ETN (89.5%), ADA (86.3%), TCZ (86.3%), GLM (85.0%), and IFX (79.3%) (Cox P = 0.043); and retention rates due to remission were: CZP (100.0%), GLM (97.7%), ADA (97.5%), ABT (96.8%), IFX (94.8%), ETN (94.4%), and TCZ (94.2%) (Cox P = 0.58).