On 27 May, the US Food and Drug Administration’s (FDA) Endocrinologic and Metabolic Drugs Advisory Committee voted 10-7 in favour of Provention Bio ’s teplizumab to delay the onset of type 1 diabetes (T1D). With a Prescription Drug User Fee Act (PDUFA) date of 2 July, it is likely that the first preventative treatment for T1D could be available by the end of the year.

Teplizumab is an Fc receptor-nonbinding anti-CD3 monoclonal antibody that works to modulate the response of the T-lymphocytes that mediate the destruction of the insulin-producing beta cells in the islets of the pancreas. GlobalData expects that teplizumab’s approval will be paradigm-changing for T1D, as it will place a greater emphasis on screening for the disease and drive the market towards precision medicine, but its limited accessibility will greatly affect its market success.

Provention based its application on results from the pivotal TN-10 study. Results from that study showed a single 14-day course of teplizumab delayed insulin-dependent, clinical-stage disease by a median of at least two years in presymptomatic patients with stage II T1D compared to placebo. Since the trial’s completion, extension studies have extended that median delay to three years, and teplizumab’s protection may last even longer as studies continue.

As T1D screening is not clinical practice in the US, the trial criteria focused on the subset of patients who have relatives with T1D. According to key opinion leaders (KOLs) interviewed by GlobalData, only 10–15% of T1D patients have a first or second-degree relative who also has the disease. Unless T1D antibody screening becomes standard of care, the eligible patient population for teplizumab remains quite small.

KOLs have also noted that a barrier to mass screening is the lack of a preventative therapeutic. Even after teplizumab’s approval, however, screening panels can be costly and, according to interviewed payers, are not likely to be reimbursed unless preventative screening for T1D is incorporated into the US Task Force of Preventive Services as a recommendation.

Despite screening expenses, payers remain hopeful that teplizumab will be reimbursed, but reimbursement is contingent on developing a large enough patient population and a long enough delay of T1D. In addition, the reimbursement criteria will likely be limited to the trial patient population, leaving out the 85–90% of newly diagnosed T1D patients who do not have a first or second-degree relative with the disease.

KOLs have been divided on the applications of teplizumab, uncertainty about its longevity and subsequent cost. Many are cautious about the psychological impacts of delaying T1D, and the long-term toll teplizumab may have. Committee members said that there needed to be more safety data, in particular regarding long-term malignancies and severe adverse events such as the risk of diabetic ketoacidosis and the three deaths documented in the study.

While the FDA committee agreed that the benefits of teplizumab outweigh the risks, committee concerns over the use of the drug are shared across the diabetes space. For example, the Provention study did not meet its enrolment goal and thus was assessed in only 44 patients. Given the issues with enrolment, it will likely be difficult to identify a clear patient population in practice.

Teplizumab is also being investigated as a treatment at the early onset of T1D, as it was shown to significantly reverse the decline of C-peptide levels. This suggests that teplizumab can not only delay the destruction of beta cells but also restore insulin production in dysfunctional beta cells. Among KOLs, there is more excitement for teplizumab as an immunotherapy to offer to patients who have been diagnosed with T1D than for the drug as just a preventative therapy. The efficacy of teplizumab as a first-line therapeutic for the disease, however, remains to be seen.

In the 8MM (the US, France, Germany, Italy, Spain, UK, Japan and Canada), GlobalData believes the number of diagnosed prevalent cases of T1D will grow at an annual growth rate (AGR) of 1.78% from 3,329,294 cases in 2019 to 3,921,695 cases by 2029. As these cases increase, there is still no approved disease-modifying treatment for T1D. Increased screening and early treatments like teplizumab are a first step to drive preventative and patient-specific care in T1D. Increased innovation in the space, however, is a critical need to address the underlying causes of T1D and advance care for all T1D patients, not just those at risk of developing the disease.