Why is MMP13 a drug target?
Because it acts at the step reviews call irreversible. MMP13 is the main enzyme cutting type II collagen in damaged cartilage, and that collagen renews very slowly. Mice without MMP13 had less cartilage erosion after injury. Broad MMP-blocking drugs caused joint and muscle side effects in people, so research turned to blocking MMP13 selectively. No MMP13 drug has reached patients.
The case for targeting it
Three findings make MMP13 attractive. It has the highest activity against type II collagen of the MMPs and is the major collagenase in damaged cartilage (Li 2011). Type II collagen loss is considered irreversible, unlike the early, reversible loss of aggrecan (Li 2011). And the collagen renews very slowly in adults, with a half-life estimated at 117 years (Verzijl 2000). A 2021 review called MMP13 the primary MMP in cartilage breakdown and an attractive target for that reason (Hu 2021).
The mouse evidence
Genetic experiments back this up. Mice engineered to make an always-active human MMP13 in their cartilage developed cartilage erosion and excessive cutting of type II collagen, which the authors took as evidence that excessive MMP13 activity can cause cartilage breakdown and joint damage (Neuhold 2001). Mice lacking MMP13 had less cartilage erosion eight weeks after a knee injury, even with aggrecan depleted. The authors saw this as support for blocking MMP13 even after damage is under way (Little 2009).
Why the first drugs failed
The first MMP-blocking drugs weren't selective. They blocked many MMPs at once, and the clinical use of these broad inhibitors was restricted by musculoskeletal side effects that depended on dose and duration (Li 2011).
One placebo-controlled trial shows what that looked like. 401 people with mild to moderate knee osteoarthritis took a broad MMP inhibitor, PG-116800, at 25, 50, 100 or 200 mg twice daily, or placebo, for 12 months (Krzeski 2007). The 200 mg dose was stopped early because of musculoskeletal side effects. After a year there was no significant difference from placebo in joint space width or in pain, stiffness and function scores. Joint pain was the most common side effect, at 35%. Some 13% of people reported hand problems, half of them in the 200 mg group, and loss of shoulder movement was more common at the two highest doses (Krzeski 2007). The authors concluded the side effect profiles of MMP inhibitors in general made them unsuitable for this use.
Selective inhibitors
The answer has been to aim at MMP13 alone. A 2011 review traced selective MMP13 inhibitor work from the late 1990s, covering compounds built to grip the enzyme's zinc site and others designed to bind elsewhere, as well as dual inhibitors of MMP13 and aggrecanase (Li 2011). The 2021 review looked at how MMP13 is controlled at the gene and epigenetic level, and at the strategies used against it (Hu 2021).
Natural compounds are being compared with these drugs too. In rats with a cut knee ligament, curcumin monoglucuronide, a curcumin metabolite, protected cartilage better than BI-4394, a specific MMP13 inhibitor (Roy 2025). The authors argued for blocking MMP-8 as well as MMP13.
Martin Lotz doubts that hitting any one enzyme will be enough.
There are probably 40 or more enzymes that are at play to destroy the joint cartilage. And these trials actually have just picked one out of those many enzymes and made inhibitors for them, and they didn't succeed in clinical trials.
Where things stand
No drug that blocks MMP13 has reached patients. None of the papers here reports an approved MMP13 medicine, and a 2021 review said there were currently no interventions available to restore degraded cartilage (Hu 2021). The wider record is no better. In a 2021 lecture Martin Lotz said a few hundred drugs had been tested as disease-modifying treatments for osteoarthritis, and every one of those trials had failed to show efficacy.
Prakash Jayabalan said the same in 2024 about drugs aimed at the MMP family.
There are a number of medications that are being targeted towards MMPs, which are those cartilage degradative enzymes within the joint, and those are not currently available on the market.
Other questions people ask
Why not just block every MMP?
That was tried. A 12-month trial of a broad MMP inhibitor in 401 people showed no benefit over placebo and caused joint, shoulder and hand side effects.
Is there an approved MMP13 drug?
No. No drug that blocks MMP13 has reached patients, and a 2021 review said no interventions were available to restore degraded cartilage.
What is a selective MMP13 inhibitor?
A compound designed to block MMP13 without blocking the other MMPs, to avoid the musculoskeletal side effects seen with broad inhibitors.
Sources
- Li NG, Shi ZH, Tang YP et al. New hope for the treatment of osteoarthritis through selective inhibition of MMP-13. Curr Med Chem 2011.
- Verzijl N, DeGroot J, Thorpe SR et al. Effect of collagen turnover on the accumulation of advanced glycation end products. J Biol Chem 2000.
- Hu Q, Ecker M. Overview of MMP-13 as a Promising Target for the Treatment of Osteoarthritis. Int J Mol Sci 2021.
- Neuhold LA, Killar L, Zhao W et al. Postnatal expression in hyaline cartilage of constitutively active human collagenase-3 (MMP-13) induces osteoarthritis in mice. J Clin Invest 2001.
- Little CB, Barai A, Burkhardt D et al. Matrix metalloproteinase 13-deficient mice are resistant to osteoarthritic cartilage erosion but not chondrocyte hypertrophy or osteophyte development. Arthritis Rheum 2009.
- Krzeski P, Buckland-Wright C, Bálint G et al. Development of musculoskeletal toxicity without clear benefit after administration of PG-116800, a matrix metalloproteinase inhibitor, to patients with knee osteoarthritis: a randomized, 12-month, double-blind, placebo-controlled study. Arthritis Res Ther 2007.
- Roy HS, Kulkarni C, Neethu KM et al. Curcumin monoglucuronide protects cartilage from progressive degeneration by blocking MMP-13. Arch Pharm Res 2025.
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