Pexidartinib Offers Hope for a Rare Tumor—But Its Risks Matter as You Age

You may hear about new cancer or immune-targeting drugs and wonder whether medical breakthroughs truly change what aging and serious illness look like in everyday life. Some treatments do extend life or reduce symptoms, but they can also bring new risks, frequent testing, and long-term care challenges that affect independence.

One medication drawing attention in research and rare-disease care is Pexidartinib (PLX3397) CSF-1R inhibitor. It is approved to treat tenosynovial giant cell tumor (TGCT), a rare condition that affects the lining of joints—most often the knee, hip, ankle, or shoulder.

TGCT can affect adults of many ages, but it is most commonly diagnosed in younger and middle-aged adults, often between their 30s and 50s. It is not considered a disease of aging, yet its impact can become more serious over time, especially if joint damage progresses.

Before pexidartinib was available, treatment relied mainly on surgery, sometimes repeated multiple times, and some people still experienced chronic pain, stiffness, or loss of mobility that interfered with work, daily activities, and quality of life. In severe cases, joint replacement became the only option.

Pexidartinib offers a non-surgical option when surgery is not appropriate or would cause significant disability, but it does not cure the condition and requires close medical monitoring because of safety risks.

The key takeaway is perspective: even conditions that are not primarily age-related can create long-term functional limitations, caregiving needs, and planning challenges later in life.

Tenosynovial Giant Cell Tumor—Life Expectancy and Progression

Tenosynovial giant cell tumor (TGCT) is almost never life-threatening. In the vast majority of cases, people with TGCT have a normal life expectancy.

The condition is considered benign, meaning it does not spread to distant organs as cancer does, and deaths directly caused by TGCT are extremely rare.

That said, TGCT can still be serious and life-altering, and can create a need for help with daily living activities.

TGCT develops in the lining of joints, tendons, or bursae and usually progresses slowly over years, not weeks or months.

There are two main patterns:

• Localized TGCT: Affects a small area, often a finger or wrist. It tends to grow slowly and is usually easier to remove with surgery.
• Diffuse TGCT: Affects larger joints such as the knee, hip, ankle, or shoulder. This form is more aggressive locally and harder to control.

As TGCT progresses, people may experience:

• Increasing joint pain and swelling
• Stiffness and reduced range of motion
• Difficulty walking, standing, or using the affected joint
• Repeated flare-ups after treatment

Over time, ongoing inflammation can damage cartilage and bone, leading to arthritis-like changes.

What Life Looked Like Before New Drug Treatments

Before medications like pexidartinib were available, surgery was often the only option. Many people required:

• Multiple surgeries over several years
• Long recovery periods
• Physical therapy
• Joint replacement in severe cases

Even with treatment, the tumor often came back, especially in the diffuse form. While people still lived full lifespans, their quality of life could decline due to chronic pain, limited mobility, and difficulty working or staying active.

Why This Matters as You Age

Although TGCT is more commonly diagnosed in younger and middle-aged adults, its effects can follow people into later life.

Joint damage accumulated over decades can lead to:

• Reduced independence
• Greater need for assistance with daily activities
• Increased reliance on caregivers
• Higher likelihood of long-term care needs

That’s why TGCT is best understood not as a fatal condition, but as a chronic disease that can quietly shape mobility, independence, and care needs over time.

What is Pexidartinib?

Pexidartinib is an oral prescription drug approved by the U.S. Food and Drug Administration for one specific condition:

• Symptomatic tenosynovial giant cell tumor (TGCT) when surgery is not appropriate or would cause severe loss of function

Pexidartinib is not approved for general cancer treatment. Its use outside TGCT remains experimental and limited to clinical research studies. However, apart from blocking this particular protein, pexidartinib (PLX3397) CSF-1R inhibitor has shown to be effective in affecting some other signaling proteins as well, that is, kinases, which can be involved in certain types of cancer. All of this means that it can be highly important in cancer research, which is exactly why scientists are so interested in understanding it more clearly, in an effort to develop better treatment solutions in the end.

How the Drug Works in the Body

Pexidartinib blocks CSF-1R signaling. When that signal is shut down:

• Macrophages lose survival signals
• Abnormal immune-cell buildup declines
• Inflammation linked to TGCT is reduced
• Tissue damage may slow

Researchers are studying whether this immune-modifying approach could enhance other cancer treatments, such as immunotherapy.

Those uses are investigational only and not standard medical care.

FDA Safety and Warnings You Should Know

This medication carries serious risks that matter even more as you get older.

Boxed Warning: Severe Liver Injury

Pexidartinib includes the FDA’s strongest safety warning for serious and potentially fatal liver toxicity.

Key safety facts from FDA prescribing information:

• Risk of severe liver injury, including liver failure
• Requires baseline and frequent blood tests to monitor liver function
• Not recommended for people with pre-existing liver disease
• Available only through a Risk Evaluation and Mitigation Strategy (REMS) program
• Must be prescribed and monitored by a doctor experienced with the drug’s risks

Source: FDA Prescribing Information and REMS Program, updated labeling

Common Side Effects (Reported in Clinical Trials)

• Elevated liver enzymes
• Fatigue
• Nausea
• Changes in taste
• Hair color changes
• Swelling in the arms or legs

Because macrophages play important roles throughout the immune system, blocking CSF-1R can have system-wide effects, not just effects at the tumor site.

Why This Matters for Older Adults and Caregivers

New treatments can feel hopeful, especially when surgery is not an option. But advanced therapies often bring:

• Ongoing medical monitoring
• Increased fatigue or weakness
• Functional limitations
• Greater reliance on family or paid caregivers

Extending life or controlling disease does not always reduce long-term care needs. In many cases, it increases them.

The Aging Reality

Health insurance and Medicare do not cover long-term care beyond short-term skilled care. If illness or treatment leads to ongoing help with daily activities, families often face difficult decisions quickly.

Many people prepare by:

• Learning early through the LTC News Education Center
• Estimating future extended care expenses using the LTC News Cost of Care Calculator
• Planning ahead by getting quotes and shopping for Long-Term Care Insurance
• Using the LTC News Caregiver Directory to search for caregivers and facilities when care is already needed

Understanding medications like pexidartinib helps clarify how serious illness can affect independence, finances, and family responsibilities.

Bottom Line

Pexidartinib represents an important advance for a specific, rare condition. It also carries significant safety risks, particularly to the liver, and requires careful medical supervision.

If you or a loved one encounters this drug in treatment discussions, ask:

• Why is the drug being recommended
• How will safety be monitored
• What support may be needed if health or mobility declines

Medical Disclaimer

This article is for educational purposes only and does not replace medical advice from your doctor. Always discuss treatment decisions and risks with a qualified healthcare professional.