The prescribing information for lomitapide in the United States and the European Union and in other countries in which lomitapide is approved contains significant limitations on use and other important warnings and precautions, including, but not limited to, a boxed warning in the Juxtapid U.S. labeling, additional monitoring which is identified by a black inverted triangle in the product information for Lojuxta in the European Union, warnings in the prescribing information for Lojuxta citing concerns over liver toxicity associated with use of lomitapide and a U.S. Risk Evaluation Mitigation Strategy ("REMS") program. The prescribing information for metreleptin in the United States and European Union contains important warnings and precautions, including but not limited to, a boxed warning on the Myalept label in the United States, citing the risk of anti-metreleptin antibodies with neutralizing activity, risk of lymphoma and a U.S. REMS program. As with the U.S. label, the Myalepta Summary of Product Characteristics in the European Union notes that the consequences of neutralizing antibodies with respect to the loss of efficacy or serious or severe infections is not well characterized but could reduce how well the leptin found naturally in the body works or how well Myalepta works.
Patients reported various adverse reactions in the Phase 3 study of lomitapide, including reports of gastrointestinal events by 93% of patients, and in the HoFH clinical trial, including diarrhea, nausea, vomiting, dyspepsia, abdominal pain, weight loss, abdominal discomfort, abdominal distension, constipation, flatulence, increased alanine aminotransferase, chest pain, influenza, nasopharyngitis, and fatigue. Elevations in liver enzymes and hepatic (liver) fat were also observed.
GL patients in the Phase 3 study of metreleptin reported various adverse drug reactions, including weight loss, hypoglycemia, decreased appetite, fatigue, neutralizing antibodies and alopecia. Additionally, although none were assessed as drug related, there were four reported treatment-emergent deaths over the course of the 14-year study duration. Upon further investigation, these reports were consistent with the underlying morbidity of lipodystrophy and included renal failure, cardiac arrest (with pancreatitis and septic shock), progressive end-stage liver disease (chronic hepatic failure), and hypoxic-ischemic encephalopathy. In the open-label, long-term, investigator-sponsored study of metreleptin for the treatment of metabolic disorders associated with lipodystrophy syndromes (initiated in 2000 and conducted at the National Institutes of Health ("NIH")), there were two cases of peripheral T-cell lymphoma and one case of a localized anaplastic lymphoma (kinase-positive anaplastic large cell lymphoma, which is a type of T-cell lymphoma). Both of the cases of peripheral T-cell lymphoma were reported in patients with acquired GL, and both had evidence of pre-existing lymphoma and/or bone marrow/hematologic abnormalities before metreleptin therapy. A third case of anaplastic large cell lymphoma occurred in the context of a specific chromosomal translocation.
These adverse events, coupled with the boxed warnings and other label restrictions, could cause healthcare providers, regulators and patients or potential patients to view the risks associated with our products as outweighing the benefits. This could cause patients to discontinue use and limit the number of new patients, thereby negatively affecting our business, financial condition, results of operations and prospects. In addition, as part of the post-marketing commitment to the FDA for both lomitapide and metreleptin, we are conducting post-marketing registries to better understand their long-term safety and effectiveness. For lomitapide, we are conducting an observational cohort study to better understand the long-term safety, patterns of use, compliance and long-term effectiveness of controlling LDL levels. For metreleptin, we are conducting a long-term, prospective, observational study (product exposure registry) to identify and better understand any serious risks related to the use of the product. Finally, we are conducting sequential programs to expand the understanding of metreleptin immunogenicity and manufacturing. The final program regarding the immunogenicity of metreleptin was initiated in 2018, and the final post-marketing study related to the manufacturing of metreleptin is expected to be completed by the deadlines set by the FDA. In addition, we are working to implement post-marking commitments in the European Union for metreleptin, including a pediatric study in GL patients, an immunogenicity program, a post-approval study in PL and a European product exposure registry. A failure to meet post-marketing commitments to the FDA, the EMA or other regulatory authorities could impact the ability to continue to market lomitapide or metreleptin, respectively, in countries where we are unable to meet such commitments. A Phase 3, randomized, multicenter, double-blind, placebo-controlled study of metreleptin in patients with partial lipodystrophy (PL) will commence at the end of Q4 2021 with registration intent to include this population in the US label.
In the course of conducting observational cohort studies, additional clinical studies (such as pursuant to a pediatric investigation plan ("PIP") in the European Union), post-marketing surveillance, or re-evaluation of any completed clinical study data could identify, additional safety information on known or unknown side effects or new undesirable side effects caused by our products or product candidates, or the data may raise other issues with respect to the products. In such instances, a number of potentially significant negative consequences could result, including:
- we may experience a negative impact on market acceptance and increased dropout rates;- regulatory authorities may suspend, withdraw or alter their approval of the relevant product;- regulatory authorities may require the addition of labeling statements, such as warnings or contraindications or distribution and use restrictions such as, for example, the modifications to the Juxtapid label to include language instructing patients to cease therapy upon the occurrence of severe diarrhea;- regulatory authorities may issue, or require us to issue additional specific communications such as safety alerts, field alerts, or "Dear Doctor" letters to healthcare professionals;- regulatory authorities may require us to recall, withdraw, or stop selling a product or take other enforcement action;- we may receive negative publicity;- we may be required to change the way the relevant product is administered, conduct additional preclinical studies or clinical trials or restrict the distribution or use of the relevant product;- patients could suffer harm, and we could be sued and held liable for harm caused to patients;- the regulatory authorities may require us to amend the relevant REMS program, Risk Management Plan or comparable equivalent; and - our reputation may suffer.
Any known safety concerns for our products or product candidates, or any unknown safety issues that may develop or be discovered, including drug interaction problems or an increase in the severity or frequency of known adverse events or the discovery of previously unknown adverse events, or the evaluation or reevaluation of study data, could prevent us from achieving or maintaining market acceptance of the respective product, affect our ability to obtain or retain regulatory marketing approval of the respective product in one or more countries, result in onerous restrictions on such approval or the implementation or modification of the REMS programs (if applicable) or risk management plans for our products, or any other enforcement actions, result in claims, lawsuits and increased regulatory scrutiny, and affect our ability to achieve our financial goals.