FDA Approves Pimicotinib (Pimjetmi) for Tenosynovial Giant Cell Tumor
In this article
One Tablet a Day for a Benign Tumour That Limits the Joint: What Does the Pimicotinib Approval Change?
On 10 November 2026, the US Food and Drug Administration (FDA) approved pimicotinib (Pimjetmi) for the treatment of symptomatic tenosynovial giant cell tumour (TGCT). The approval covers adult patients in whom surgery may worsen loss of function or cause severe morbidity. In the registration trial MANEUVER, the proportion of patients whose tumour shrank markedly at week 25 was 56% with pimicotinib and 3.2% with placebo; joint movement, pain and daily function also improved significantly. Pimicotinib is the third CSF1R inhibitor approved for this disease and the first option taken once a day. In this article I explain what TGCT is, how the drug works, the trial results, the side effects and the situation in Türkiye. You can find the basics of benign and malignant tumours in my article on cancer biology.
- Approval: On 10 November 2026, the FDA approved pimicotinib (Pimjetmi) for adults with symptomatic TGCT in whom surgery may cause loss of function or severe morbidity. The drug had been approved in China in December 2025.
- Efficacy: In MANEUVER (94 patients, placebo-controlled), the response rate at week 25 was 56% versus 3.2% (FDA analysis; 54% in the Lancet publication). In 77% of responders the response lasted at least 12 months; joint movement, pain and physical function improved significantly.
- Safety: Common side effects are itching, rash, swelling of the face and around the eyes, and fatigue; blood tests show increases in CK and liver enzymes. There are warnings for hepatotoxicity and embryo-fetal toxicity. Only 1.6% of patients stopped treatment because of side effects.
- Türkiye: At the time of writing, I could not verify that pimicotinib or the other CSF1R inhibitors are licensed in Türkiye; access may be possible through importation of unlicensed medicines (named-patient import) with Ministry of Health approval.
Why does this matter?
TGCT is a rare, benign tumour of the membrane (synovium) that lines the joints and tendon sheaths. It does not spread to distant organs and does not shorten life expectancy; but, especially in the diffuse type, it can wear down the joint over the years and lead to pain, swelling, restricted movement and permanent loss of function. Most patients are working, active people in their 20s to 40s (types of tumour).
Surgery is the mainstay of treatment. In the diffuse type, however, the tumour spreads throughout the joint and is difficult to remove completely; the recurrence rate after arthroscopic surgery can reach around 40%. Repeated operations wear the joint down further, and some patients end up needing a joint replacement or more extensive procedures. For this reason, an effective, safe drug treatment that can be used for a long time has long been needed for patients in whom surgery is risky or insufficient (pain treatment).
What is tenosynovial giant cell tumour (TGCT)?
Tenosynovial giant cell tumour is a rare, benign tumour that develops in the membrane lining the joints, bursae and tendon sheaths. It does not spread to distant organs, but it can cause pain, swelling, locking and restricted movement in the joint. There are two types, localised and diffuse; the diffuse type used to be called pigmented villonodular synovitis (PVNS).
The localised type usually appears as a single, well-defined nodule in the hand and fingers and can generally be removed completely with surgery. The diffuse type appears as widespread thickening of the synovium, most often in the knee, followed by the ankle and hip; about three quarters of diffuse-type tumours are in the knee. According to US data, about 11 new cases occur per million people each year. The diagnosis is made with MRI of the joint and, if needed, a biopsy (what is a biopsy?).
Figure 1 · Two types: localised and diffuse
Differences in site, extent and surgery
How does pimicotinib work?
TGCT has an interesting biology: the true tumour cells are a minority within the mass. Because of a genetic change, these cells overproduce a signalling molecule called CSF1, and CSF1 recruits large numbers of immune cells called macrophages to the site. As a result, most of the mass is made up of these recruited macrophages. Pimicotinib is a kinase inhibitor that selectively blocks the CSF1R receptor on the surface of macrophages. When the signal is cut off, macrophage accumulation decreases, the mass shrinks and the swelling and pain in the joint subside (targeted therapies).
Figure 2 · How the disease and the drug work
Few tumour cells, many macrophages
What did the MANEUVER trial show?
The approval is based on MANEUVER, an international, double-blind, placebo-controlled phase 3 trial published in the Lancet in 2026. At 40 centres in Asia, Europe and North America, 94 patients with symptomatic TGCT, at least one measurable tumour of 2 cm or more, and in whom surgery could cause loss of function or severe morbidity were randomised 2:1 to pimicotinib (63 patients) or placebo (31 patients). The primary endpoint was the objective response rate at week 25, assessed on MRI by independent radiologists (what is a clinical trial?).
Figure 3 · Design of the MANEUVER trial
Double-blind, placebo-controlled, international
The results are clear: at week 25, the proportion of patients whose tumour shrank markedly was 56% (95% CI 42-68) with pimicotinib and 3.2% with placebo (FDA analysis; in the Lancet publication 34 of 63 patients, i.e. 54%). The absolute difference is about 51 percentage points. The responses appear durable: the median duration of response has not yet been reached; among the 35 responders, the response lasted at least 6 months in 91% and at least 12 months in 77%. In the longer follow-up data shared by the company (median 14.3 months), the response rate rose to 76.2%.
The response deepens and lasts over time
Patients treated with pimicotinib; MANEUVER.
Long-term follow-up data may include patients who switched from placebo to pimicotinib and are taken from a company statement. The median duration of response has not yet been reached.
From my point of view, what matters even more is how tumour shrinkage translates into the patient's daily life. At week 25, compared with placebo, the pimicotinib arm showed an increased range of joint motion, less worst pain, less joint stiffness and a significant improvement in patient-reported physical function. In a benign disease, this is exactly the real goal of treatment: a joint that moves freely and without pain (exercise and movement).
Can it be compared with the other CSF1R inhibitors?
There is no head-to-head comparison. In the registration trials, the response rate at week 25 was reported as 39% with pexidartinib (ENLIVEN), 40% with vimseltinib (MOTION) and 54-56% with pimicotinib (MANEUVER); in all trials, responses in the placebo arm were almost non-existent. Although the trial designs are similar, the patient populations and time periods differ, so it would not be right to rank the drugs on these numbers. The real differences lie in dosing frequency and side-effect profile: pexidartinib requires close monitoring because of the risk of serious hepatotoxicity, whereas vimseltinib is taken twice a week and pimicotinib once a day (reading research results correctly).
Response rate in the registration trials of drugs approved for TGCT
Objective response at week 25 by independent radiology review; each trial with a placebo arm.
Comparisons across different studies are indirect; patient populations, prior treatments and follow-up times differ. Although response criteria and patient characteristics were similar across the trials, the drugs have not been compared directly with each other. The Lancet publication reported a rate of 54% for MANEUVER; the FDA analysis reported 56%.
Figure 4 · Approved CSF1R inhibitors
Same target, different profile
Side effects and precautions
According to the FDA announcement, the side effects seen in more than 20% of patients are itching, rash, swelling of the face and around the eyes, fatigue, nausea, headache and swelling of the legs (oedema, fatigue). In blood tests, the muscle enzyme creatine phosphokinase (CK), lactate dehydrogenase, liver enzymes, lipase, amylase and cholesterol are frequently raised; most of these cause no symptoms but need to be monitored. In MANEUVER, the only grade 3 or 4 side effect exceeding 10% was raised CK (13%); dose reduction was needed in 8% and discontinuation in 1.6% (liver enzymes, cholesterol).
The product information contains three warnings: hepatotoxicity, embryo-fetal toxicity and an increase in serum creatinine without affecting kidney function. This last point is an important detail: a rise in creatinine does not by itself mean kidney damage; it is related to the drug's effect on creatinine excretion. Unlike with pexidartinib, no cholestatic liver injury or serious drug-related liver injury was reported in the trial; even so, liver tests need to be monitored regularly. The drug is taken at 50 mg once daily, with or without food.
Figure 5 · Side effects and warnings
According to the FDA announcement
Who does this approval cover?
The approval covers adults with symptomatic TGCT in whom surgery may worsen loss of function or cause severe morbidity. In other words, for tumours that can be removed easily and completely, mostly of the localised type, surgery remains the first option. For small tumours that cause no symptoms, monitoring may also be an option. I think the decision should be made jointly by orthopaedic, radiology and oncology specialists.
Figure 6 · Who does this approval cover?
Scope and situations that are not a priority
Figure 7 · Treatment pathway
Five steps from diagnosis to follow-up
Open questions
- How long should treatment last? CSF1R inhibitors shrink the tumour but do not eradicate it. Earlier experience shows that, in some patients, the tumour can grow again after the drug is stopped. The optimal duration of treatment and follow-up after stopping have not yet been established.
- Long-term safety: We are talking about a treatment that may last for years in young, active patients; how the effects on the liver, muscles and cholesterol evolve over the long term needs to be monitored.
- Use alongside surgery: Using the drug to shrink the tumour before surgery or to prevent recurrence after surgery is not yet a proven approach (the drug approval process).
- Pregnancy: A substantial proportion of patients are women of childbearing age; effective contraception is needed throughout treatment, and for patients planning a pregnancy the decision needs to be discussed separately.
The situation in Türkiye
- Licence: At the time of writing, I could not verify that pimicotinib, vimseltinib or pexidartinib is licensed in Türkiye. The worldwide commercial rights to pimicotinib are held by Merck KGaA (EMD Serono in the US); application processes in Europe and other countries are ongoing (access to FDA-approved drugs in Türkiye).
- Access route: For unlicensed drugs, importation of unlicensed medicines (named-patient import, through TEB) with Ministry of Health approval may be an option; the conditions of this route and the reimbursement status vary by drug and by patient (importation of unlicensed medicines, SGK reimbursement conditions).
- Team approach: TGCT is a rare disease; it is important that diagnosis and treatment are planned jointly at centres with experience in orthopaedic oncology, musculoskeletal radiology, pathology and medical oncology.
- Rehabilitation: After drug treatment or surgery, physiotherapy plays a decisive role in regaining joint movement and muscle strength (exercise is a medicine).
Questions you can ask your doctor
- Is my tumour localised or diffuse; can it be removed completely with surgery?
- How much damage would surgery do to my joint, and what is the risk of recurrence?
- Is CSF1R inhibitor treatment suitable in my case; which drug could I access, and how?
- Which blood tests should I have during treatment, and how often?
- How long will I take the treatment, and what will happen when I stop?
- "TGCT is a type of cancer and it spreads." No. It is a benign tumour and does not spread to distant organs; however, it can damage the joint.
- "Surgery is no longer needed." No. For tumours that can be removed easily, surgery remains the first option; the drug is for patients in whom surgery is risky or insufficient.
- "The drug makes the tumour disappear completely." In most patients the tumour shrinks and symptoms subside; however, regrowth may occur in some patients when the drug is stopped.
- "If my creatinine has gone up, my kidneys are damaged." A creatinine increase due to pimicotinib can occur without impairing kidney function; your doctor should make the assessment.
- "Itching and rash are not a serious problem, so there is no need to mention them." These side effects are usually mild, but they are easily managed when reported early (skin side effects, common misconceptions).
Frequently Asked Questions
- What is tenosynovial giant cell tumour (TGCT)?
- It is a rare, benign tumour that develops in the membrane lining the joints and tendon sheaths. It does not spread to distant organs, but it can cause pain, swelling and restricted movement in the joint. There are two types: localised and diffuse.
- What is pimicotinib and how does it work?
- Pimicotinib is a CSF1R inhibitor taken by mouth once a day. It shrinks the mass by blocking the CSF1R receptor on the macrophages recruited by the tumour. The FDA approved it on 10 November 2026.
- How effective is pimicotinib?
- In the MANEUVER trial, the proportion of patients whose tumour shrank markedly at week 25 was 56% with pimicotinib and 3.2% with placebo. In 77% of responders the response lasted at least 12 months; joint movement, pain and daily function also improved.
- Is pimicotinib available in Türkiye?
- At the time of writing, it could not be verified that it is licensed in Türkiye. Access may be possible through importation of unlicensed medicines with Ministry of Health approval; ask your treatment team for details.
Glossary
- Tenosynovial giant cell tumour (TGCT)
- A rare, benign tumour arising from the lining of joints and tendon sheaths.
- Synovium
- The thin membrane lining the inner surface of joints and tendon sheaths.
- Localised type
- TGCT in the form of a single, well-defined nodule; mostly in the hand and fingers.
- Diffuse type
- Widespread involvement of the synovium; mostly in the knee and ankle, formerly called PVNS.
- CSF1
- A signalling molecule that recruits macrophages and makes them multiply.
- CSF1R
- The receptor on the surface of macrophages that recognises CSF1; the target of pimicotinib.
- Macrophage
- An immune system cell that settles in tissues and clears debris.
- Objective response rate
- The proportion of patients whose tumour shrinks by a defined amount.
- Kinase inhibitor
- A group of drugs that suppress enzymes involved in signalling inside the cell.
- Project Orbis
- An international programme in which the FDA reviews cancer drugs concurrently with other countries' authorities.
DROZDOGAN Academy Commentary
Although benign, TGCT is a disease that can seriously restrict young people's lives. The pimicotinib approval broadens the options for patients for whom surgery is not the answer.
⚡ Why it matters
It is the third drug aimed at the same target, but it stands out with once-daily dosing, marked and durable responses, real improvement in function and a very low discontinuation rate. A well-tolerated drug that can be used for a long time is very valuable for this disease.
✅ Strengths
International, double-blind, placebo-controlled design; independent radiology review; measurement not only of tumour shrinkage but also of outcomes patients feel, such as movement, pain and function.
⚠️ Limitations
A relatively small number of patients (94); a short double-blind period (25 weeks); about half of the patients were from China; long-term safety and the course after stopping treatment are not yet known; no head-to-head comparison with the other CSF1R inhibitors.
🩺 In practice
In my patients with diffuse or recurrent TGCT, or where surgery would put joint function at risk, I see CSF1R inhibitors as a strong option. When starting treatment, I make a monitoring plan for liver tests, CK and cholesterol, and I discuss contraception and treatment duration openly with the patient.
❓ Open questions
How long should treatment last, and what happens when it is stopped? Does use alongside surgery reduce recurrence? Among the three CSF1R inhibitors, which one suits which patient best?
Bottom line: Pimicotinib is a new, well-tolerated option that provides effective, durable responses in symptomatic TGCT where surgery is risky. For patients in Türkiye, the real question will be access.
- This article was prepared in November 2026.
- The information is taken from the FDA approval announcement of 10 November 2026, the Lancet publication of the MANEUVER trial, statements from Merck KGaA, and FDA and European approval information for the other CSF1R inhibitors.
- The response rate was reported as 56% in the FDA analysis and 54% in the Lancet publication; the difference may stem from differences in data cut-off and methods between the analyses. The long-term follow-up data are taken from a company statement and have not yet been reported in detail in a peer-reviewed publication.
- The licensing and reimbursement status of the drugs in Türkiye could not be verified. Cross-trial comparisons are indirect. The illustrations are simplified. The Academy commentary is my own.
- This article is not medical advice; make your health decisions together with your doctor.
References
- U.S. Food and Drug Administration. FDA approves pimicotinib for symptomatic tenosynovial giant cell tumor. 10 November 2026. fda.gov
- Pimicotinib versus placebo for tenosynovial giant cell tumour (MANEUVER): an international, randomised, placebo-controlled, phase 3 trial. Lancet 2026. doi:10.1016/S0140-6736(25)02602-9. abstract
- Merck KGaA, Darmstadt, Germany. Pimicotinib approved as systemic treatment in China for tenosynovial giant cell tumor. 22 December 2025. emdgroup.com
- U.S. Food and Drug Administration. FDA approves vimseltinib for symptomatic tenosynovial giant cell tumor. 14 February 2025. fda.gov
- Deciphera. European Commission approval of ROMVIMZA (vimseltinib) for TGCT. September 2025. businesswire.com
- Tap WD, Gelderblom H, Palmerini E, et al. Pexidartinib versus placebo for advanced tenosynovial giant cell tumour (ENLIVEN): a randomised phase 3 trial. Lancet 2019;394:478-487. doi.org
- West RB, Rubin BP, Miller MA, et al. A landscape effect in tenosynovial giant-cell tumor from activation of CSF1 expression by a translocation in a minority of tumor cells. Proc Natl Acad Sci USA 2006;103:690-695. doi.org
- Giustini N, Bernthal NM, Bukata SV, Singh AS. Tenosynovial giant cell tumor: case report of a patient effectively treated with pexidartinib (PLX3397) and review of the literature. Clin Sarcoma Res 2018;8:14. pmc.ncbi.nlm.nih.gov
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