The US Food and Drug Administration (FDA) is currently reassessing the approval of Roche’s flagship drug, ocrelizumab (marketed as Ocrevus), specifically for its use in treating primary progressive multiple sclerosis (PPMS). PPMS, a debilitating subtype of multiple sclerosis affecting roughly 15% of individuals with the disease, has posed significant clinical challenges due to the limited efficacy of available therapies. Ocrelizumab initially garnered attention as a pioneering treatment following its 2017 approval, but emerging concerns are now prompting critical scrutiny of its benefit-risk profile, particularly regarding its effectiveness in female patients and potential cancer risks.
Internal FDA review documents and testimonies from agency scientists reveal a striking divergence from the agency’s final decision to approve the drug. Several FDA evaluators voiced alarm over what they described as “near zero efficacy” in certain patient subsets and an “unusual imbalance” in incidence rates of breast cancer among women treated with ocrelizumab. These findings stem from clinical trial data that suggested limited therapeutic gains in women with PPMS, alongside a troubling signal that breast cancer occurrences were disproportionately elevated, warranting caution. Moreover, issues with data integrity at some clinical trial sites, coupled with manufacturing quality concerns, further compounded doubts about the robustness of the evidence supporting approval.
The unfolding saga intensified after MS patient advocate Kaylin Bower uncovered the FDA’s internal review memos. Bower expressed profound shock at the degree of skepticism expressed by the agency’s own scientists, many of whom recommended against approving ocrelizumab for PPMS on grounds that effectiveness was insufficient and the safety profile raised red flags. Her efforts catalyzed the FDA’s decision to formally revisit the drug’s approval status, underscoring the critical role of patient advocates in regulatory oversight and transparency.
Despite these warnings, in 2017 the then-head of neuroscience at the FDA, Billy Dunn, greenlit ocrelizumab approval without convening the agency’s external advisory committee, bypassing a standard step in controversial drug endorsements. Dunn’s directive mandated labeling updates to highlight breast cancer risk and called for an observational study to investigate long-term safety post-approval. Yet this safety study is not expected to report until the late 2030s, leaving a protracted period during which safety signals linked to cancer risk remain unresolved, fueling ongoing debate within the medical community.
Critics argue that the approval of ocrelizumab for PPMS has been oversold in terms of its clinical utility, particularly when long-term data remain scant and benefits appear limited to patients exhibiting active disease progression. Without compelling evidence supporting widespread long-term treatment, some experts suggest reining in its use to shorter courses or strictly in those showing demonstrable benefit. Such recommendations underscore the wider issue of stratifying treatment indications based on rigorous, sex-disaggregated clinical outcomes—an imperative often overlooked in drug development and approval processes.
Roche, the pharmaceutical giant behind ocrelizumab, staunchly defends the drug’s safety profile and therapeutic value. The company cites unpublished interim analyses that purportedly refute claims of sex-based disparities in efficacy and downplay the breast cancer risk as an incidental finding unrelated to the drug. However, Roche has declined to make this data publicly available, referencing publication embargoes, which has bred skepticism among independent researchers and clinicians who call for full transparency to enable objective risk-benefit assessment.
This controversy surrounding ocrelizumab is not an isolated regulatory embarrassment for the FDA. Billy Dunn, who authorized its approval, also oversaw the contentious approvals of Alzheimer’s drugs aducanumab in 2021 and lecanemab in 2023. Both approvals faced intense criticism from expert reviewers and investigators, with aducanumab’s approval process being subject to Congressional inquiry for “rife irregularities.” These cases collectively reveal fractures in the FDA’s accelerated approval frameworks, which are intended for breakthrough drugs addressing unmet medical needs but have increasingly been questioned for possible lowered evidentiary standards and compromised scientific rigor.
Moreover, the revolving door between regulatory agencies and the pharmaceutical industry raises ethical concerns. Dunn’s departure from the FDA in 2023 to join Prothena, a biotech firm developing Alzheimer’s therapies, exemplifies the complex interplay between drug regulators and industry stakeholders. This transition underscores possible conflicts of interest and challenges in ensuring unbiased drug evaluation amid career incentives linked to private sector opportunities.
At the heart of the ongoing FDA review is the fundamental question of whether current approval mechanisms adequately safeguard patient health while fostering innovation. The case of ocrelizumab underscores the tension between expedited access to potentially life-altering medications and the necessity for stringent, transparent evidence on efficacy and safety—especially for chronic, disabling conditions with limited options like PPMS. As more data become available and regulatory agencies reassess previously granted approvals, stakeholders hope for recalibrated policies that elevate patient safety without stifling therapeutic advancements.
As the scientific community awaits forthcoming data from long-term safety studies, the spotlight remains firmly on Roche and the FDA’s handling of this high-profile treatment. The outcome of this review process may well influence future regulatory frameworks, calling for heightened post-market surveillance, improved trial designs incorporating sex-specific analyses, and a more cautious approach to balancing benefits and risks in vulnerable patient populations. Meanwhile, patients, clinicians, and advocates continue to demand clarity and accountability to ensure that therapeutic promises translate into genuine, equitable health gains.
In summary, the case of ocrelizumab for primary progressive multiple sclerosis exposes deep fissures in the nexus of pharmaceutical innovation, regulatory oversight, and patient advocacy. It highlights the urgent need for robust, sex-disaggregated clinical evidence and unwavering transparency when evaluating breakthrough therapies intended for unmet medical needs. As scrutiny intensifies, the hope remains that regulatory reforms will emerge stronger and more patient-centric, safeguarding public trust and optimizing therapeutic impact in complex neurological diseases.
Subject of Research: Primary Progressive Multiple Sclerosis, Ocrelizumab (Ocrevus), Drug Safety and Efficacy, FDA Drug Approval Process
Article Title: Multiple sclerosis: Could Roche’s bestselling drug Ocrevus be doing more harm than good in women with primary progressive MS?
News Publication Date: 15-Apr-2026
Web References:
http://dx.doi.org/10.1136/bmj.s666
References:
BMJ Investigations Unit
Keywords: Multiple sclerosis, primary progressive MS, ocrelizumab, FDA approval, breast cancer risk, drug safety, sex-based efficacy, neurological disorders, clinical trials, regulatory science, pharmaceutical oversight, autoimmune disorders
