Proteus syndrome is an exceptionally rare genetic condition that causes certain parts of the body to grow in ways that are difficult to predict and control. The approach to managing this complex disorder involves both established medical care aimed at preventing complications and emerging experimental therapies being tested in clinical trials, offering new hope for those affected by this challenging condition.

Managing a Rare and Unpredictable Condition

Proteus syndrome presents unique challenges because it affects each person differently and changes over time. The main goal of treatment is not to cure the condition, but to help individuals live more comfortably and safely despite its effects. Treatment focuses on preventing serious complications, maintaining mobility and function, and addressing specific problems as they arise. Because the overgrowth can affect bones, skin, blood vessels, and other tissues in unpredictable patterns, each person needs a care plan tailored to their specific situation.^[1]

The condition requires lifelong monitoring because new areas of overgrowth can appear over time, and existing overgrowth tends to worsen, especially during childhood. Medical teams must watch carefully for complications that can become life-threatening, such as blood clots forming in the legs or lungs. The asymmetric nature of the overgrowth, meaning one side of the body may be affected more than the other, creates additional challenges for movement, balance, and daily activities.^[2]

Treatment decisions depend heavily on which parts of the body are affected, how severe the overgrowth is, and what functional problems or health risks are present. A multidisciplinary team of specialists works together to address the many different aspects of the syndrome. This team-based approach is essential because Proteus syndrome can impact so many body systems simultaneously.^[6]

Standard Medical and Surgical Management

The foundation of Proteus syndrome treatment involves careful monitoring and timely intervention to prevent or address complications. There is currently no cure for the condition, so medical care focuses on managing symptoms and maintaining the best possible quality of life. Regular check-ups with various specialists allow doctors to track changes and respond quickly when problems develop.^[6]

One of the most critical aspects of standard care involves preventing and treating deep vein thrombosis, which means blood clots forming in the deep veins of the legs. These clots are particularly dangerous because they can break loose and travel to the lungs, causing a potentially fatal condition called pulmonary embolism. This is one of the leading causes of death in people with Proteus syndrome. Doctors may recommend anticoagulation therapy, which are medications that help prevent blood clot formation, especially before and after surgical procedures. The decision to use these medications must be made carefully for each individual, weighing the risk of dangerous clots against the risk of excessive bleeding.^[1][14]

Surgical intervention plays a major role in managing Proteus syndrome when overgrowth creates functional problems or health risks. Orthopedic surgeons may perform procedures to address leg length discrepancies, which occur when one leg grows significantly longer than the other, making walking difficult and causing secondary problems like joint pain and muscle strain. Progressive curvature of the spine, called scoliosis, may require surgical correction to prevent further complications. Early recognition and monitoring of spinal problems can sometimes allow for non-surgical approaches to slow progression.^[14]

When fingers or toes become extremely enlarged through a condition called macrodactyly, surgical reduction or, in severe cases, amputation may be necessary to allow the person to wear shoes, hold objects, or perform daily activities. These are difficult decisions that must balance functional improvement against the risks and consequences of surgery. Similarly, when bone overgrowth affects the face or tongue, causing problems with breathing, eating, or severe misalignment of the teeth, surgical intervention by a craniofacial team may be required.^[14]

Skin lesions and overgrowths require ongoing attention from dermatologists who specialize in skin conditions. Thick, raised skin growths called cerebriform connective tissue nevi, which have a characteristic brain-like appearance with deep grooves, often form on the soles of the feet. These can make walking painful and difficult. While these lesions are almost never seen in other conditions, making them a hallmark of Proteus syndrome, they are challenging to treat. Various approaches have been tried with limited success, including laser treatments, surgical removal, and other techniques.^[4][14]

Physical therapy and occupational therapy are invaluable for helping people with Proteus syndrome maintain mobility and independence. These therapists work on exercises to strengthen muscles, improve balance, and maintain joint flexibility despite asymmetric growth. They also help with adaptations such as custom footwear, orthotics, and assistive devices that make daily activities easier and safer. The goal is to maximize function and prevent secondary problems like muscle weakness or joint contractures.^[6]

People with Proteus syndrome need regular imaging studies to monitor internal organs and detect problems early. Magnetic resonance imaging (MRI) and computed tomography (CT) scans can reveal internal overgrowths such as fatty tumors called lipomas, lung cysts, or other structural abnormalities that may not cause symptoms initially but could lead to serious complications if left undetected. These imaging studies guide treatment decisions and help doctors intervene before problems become severe.^[14]

Some individuals with Proteus syndrome have an increased risk of developing certain tumors, although most are benign, meaning they are not cancerous. These include ovarian cysts in females, which can grow very large and cause serious complications. Regular ultrasound monitoring of the ovaries is important for detecting and addressing these cysts before they cause problems. Other tumors that may develop include growths in the salivary glands and membranes covering the brain. While the overall risk of these tumors is increased compared to the general population, they remain relatively uncommon.^[1][4]

Innovative Treatments Being Tested in Clinical Trials

The discovery in 2011 that Proteus syndrome is caused by a specific mutation in the AKT1 gene opened the door to developing targeted treatments. This genetic mutation causes cells to grow and divide excessively because the normal signals that control cell growth are disrupted. Understanding this molecular basis led researchers to investigate whether drugs that could block this abnormal AKT1 activity might help control the overgrowth seen in Proteus syndrome.^[5]

The most promising experimental treatment currently being studied is a drug called miransertib, also known by its research code ARQ 092. This medication was originally developed for treating certain types of cancer that involve the same AKT pathway, but researchers realized it might also help people with Proteus syndrome. Miransertib works by blocking the overactive AKT1 protein, potentially slowing or stopping the abnormal cell growth that causes the characteristic overgrowth of the syndrome.^[12]

Clinical trials of miransertib have been conducted primarily at the National Institutes of Health in Bethesda, Maryland, in the United States. The first studies, called Phase I trials, focused on determining the correct dose and establishing that the medication was safe for people with Proteus syndrome. These early trials included both adults and children. Researchers found that much lower doses than those used in cancer treatment were effective and well tolerated in Proteus syndrome patients.^[12]

The initial dose-finding study showed encouraging results. Participants experienced fewer side effects than expected, with the most common being dry mouth, mouth inflammation called gingivostomatitis, and some dental problems in people who already had gum disease. These side effects generally resolved on their own without requiring treatment to be stopped. Importantly, the drug appeared safe even in children, which is crucial since Proteus syndrome typically causes the most rapid growth during childhood.^[12]

More detailed reports from patients taking miransertib have documented improvements in several areas. One twenty-year-old patient who took the medication for an entire year showed measurable reductions in the size of skin lesions and fatty overgrowths. The cerebriform connective tissue nevi on his feet, which had been thick and bothersome, became noticeably thinner and flatter. Large fatty masses decreased in volume. Perhaps most importantly, the patient reported significant pain reduction, which greatly improved his quality of life. The medication was well tolerated throughout the year-long treatment period.^[13]

The mechanism of action of miransertib is quite specific. The drug is what scientists call an allosteric inhibitor of AKT, meaning it binds to the AKT1 protein at a location different from where the protein normally becomes activated, changing its shape and preventing it from working. This is important because the goal is not to kill cells as in cancer treatment, but rather to reduce their abnormal growth while keeping both normal and affected cells functioning. In Proteus syndrome, only some cells in the body carry the AKT1 mutation, a pattern called mosaicism, so completely eliminating all affected cells would damage or destroy entire organs and tissues. Instead, the drug aims to “turn down” the overactive growth signal to more normal levels.^[12]

Following the promising initial results, researchers began Phase II clinical trials, which are designed to more rigorously evaluate whether miransertib actually provides clinical benefit. These studies compare patients’ conditions before and after treatment, measuring changes in the size of overgrowths, pain levels, functional abilities, and quality of life. The Phase II trials are ongoing, with the goal of determining whether miransertib should move forward to larger Phase III studies that would compare it against standard care and potentially lead to regulatory approval.^[12]

The trials have revealed important considerations about treatment timing and patient selection. Some evidence suggests that miransertib may be more effective when started earlier in life, when overgrowth is actively progressing, rather than in older patients where overgrowth has stabilized. Researchers are carefully studying whether there might be critical windows of time when treatment would be most beneficial. They also need to ensure that doses strong enough to control overgrowth do not interfere with normal growth and development in children.^[18]

Long-term safety remains an important question. While short-term use of miransertib appears safe, the AKT pathway is involved in many normal cellular functions, including immune system function, metabolism, and normal tissue repair. Researchers are monitoring trial participants carefully for any unexpected effects that might emerge with prolonged use. The balance between benefit and risk will be crucial in determining whether miransertib becomes an approved treatment for Proteus syndrome.^[12]

Patient experiences with miransertib vary considerably. Some individuals report noticeable improvements in pain, reduction in the size of overgrowths, and better overall function. Others, particularly older adults whose overgrowth had already stabilized, have not experienced dramatic benefits. This variation suggests that treatment response may depend on factors such as age, the severity and pattern of overgrowth, and the specific tissues affected.^[18]

Beyond miransertib, researchers continue to explore other potential therapeutic approaches. Because the AKT pathway is part of a larger signaling network called the PI3K/AKT/mTOR pathway, other drugs that target different points in this network might also prove useful. Some experimental therapies being studied in other overgrowth syndromes or cancers involving similar genetic changes could potentially be adapted for Proteus syndrome if they show promise.^[9]

Gene therapy, which would involve correcting or compensating for the AKT1 mutation at the genetic level, represents a theoretical future approach. However, the mosaic nature of Proteus syndrome, with the mutation present in only some cells scattered throughout the body, makes gene therapy technically challenging with current technology. Researchers continue to develop new gene-editing tools that might eventually make this approach feasible.^[2]

Most Common Treatment Methods

• Surgical Interventions
  • Orthopedic surgery to correct leg length discrepancies and bone deformities
  • Spinal surgery for progressive scoliosis
  • Reduction or amputation of excessively enlarged digits
  • Craniofacial surgery for facial overgrowth or tongue enlargement
  • Removal of problematic skin lesions
• Medical Management
  • Anticoagulation therapy to prevent blood clots
  • Regular monitoring with imaging studies (MRI, CT, ultrasound)
  • Screening for tumors and ovarian cysts
  • Management of neurological complications
• Rehabilitation Therapies
  • Physical therapy to maintain mobility and strength
  • Occupational therapy for daily living activities
  • Custom orthotics and adaptive footwear
  • Assistive devices for mobility and function
• Experimental Treatments in Clinical Trials
  • Miransertib (ARQ 092): an AKT inhibitor drug being tested in Phase II trials
  • Other targeted therapies affecting the PI3K/AKT/mTOR pathway
  • Clinical trials conducted primarily at the National Institutes of Health in the United States
• Supportive Care
  • Dermatological treatment for skin overgrowths
  • Dental and orthodontic care
  • Pain management
  • Psychological support for coping with visible differences