As the name implies, a rare disease is an illness that affects far fewer people than more common conditions, like breast cancer or heart disease. Today, however, 7,000 rare conditions have been identified, and these affect more than 350 million people worldwide, a figure roughly equal to the U.S. population.
Clearly, both the individual burden and the collective health impact of rare diseases are significant.
Legacy of enzyme replacement therapy fuels innovation
Sanofi has a long-standing commitment to rare diseases. That work began some 35 years ago when the biotech pioneer Genzyme, now a part of Sanofi, discovered its first rare disease treatments. The scientific approach that they apply to rare diseases is a simple one: in order to devise effective therapies, disease biology must first be fully scrutinized and understood. Such deep, mechanistic knowledge can help to reveal what is missing molecularly, as well as to point to ways in which science can help.
This powerful approach yielded the first enzyme replacement therapy for Gaucher disease — a rare, inherited lysosomal storage disorder, in which the lack of a specific enzyme causes substances to accumulate abnormally within cells. Remarkably, many lysosomal storage disorders can now be treated based on this principle, with biopharmaceuticals that supply the relevant missing enzyme.
Today, Sanofi is working to extend this legacy to cover even more rare diseases.
“There are millions of patients who are in need,” said Dr. Dietmar Berger, global head of development at Sanofi. “That is why we and our colleagues are creating therapies for the rare diseases that lack them.”
One example is Niemann-Pick disease types A, B, and A/B (also known as acid sphingomyelinase deficiency or ASMD). This condition causes fat to build-up in cells throughout the body. Dietary restrictions do not change the course of the disease. Tragically, ASMD can be fatal. Effective therapies that can meaningfully improve patients’ lives are urgently needed. “Our hope is that these potential new treatments will help a broader swath of people with rare diseases,” Berger said.
While a deep understanding of disease biology has helped fuel these new therapies, so, too, have state-of-the-art biotechnology platforms.
“We’re bringing a variety of technologies to bear on rare diseases,” said Dr. Yong-Jun Liu, head of research at Sanofi. “Those range from novel antibody-based technologies to gene therapy and genomic medicine, which are particularly exciting, as the vast majority of rare diseases are due to inherited defects in a single gene.”
When rare becomes more common
Drug discovery in rare disease demonstrates the power of molecularly-defined therapies — a principle that has also been applied in common diseases, especially recently, as new details emerge about the molecular drivers of conditions ranging from certain types of cancers to heart disease to neurodegeneration. This knowledge is also leading to an increased appreciation of disease heterogeneity. For example, breast cancer is now recognized not as one homogeneous illness, but rather a multitude of different subtypes, each with distinct molecular profiles. In this way, many common diseases can, in fact, be viewed as a collection of molecularly distinct conditions, each of which is much more rare than the broader catch-all category of breast cancer, for example.
Just as this deep understanding of disease biology can highlight previously unknown differences, it can also uncover intriguing areas of overlap. For example, Sanofi is now pursuing an experimental therapy that targets molecular vulnerabilities shared across multiple conditions, including Gaucher disease — a rare disease — and a specific subtype of Parkinson’s disease, a much more common condition. This kind of molecularly-tailored therapy represents a real paradigm shift in Parkinson’s disease treatment.
So, as we recognize Rare Disease Day this February, it is important to celebrate the remarkable progress that has been made for people living with a rare disease. At the same time, let us also stay focused on bringing even more innovation to rare disease research and drug development, because those efforts promise to benefit not just one patient, but the many. It’s the patients who inspire Sanofi scientists to persevere in their efforts.