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Highlights from

American College of Rheumatology

annual meeting 2018

Chicago, Illinois 19-24 October 2018

Intra-articular TPX-100 for knee tibiofemoral osteoarthritis: recent data from TPX-100-1

Take-home messages
  • TPX-100 demonstrated statistically significant and clinically meaningful improvements in knee function and other clinical parameters in patients with tibiofemoral as well as patellofemoral knee osteoarthritis
  • Results were seen at 6 and 12 months after a single series of 4 weekly intra-articular injections
  • Intra-articular injections of TPX-100 were well tolerated by patients and no likely or drug-related severe adverse events were observed
“These findings support TPX-100 as a candidate disease and structure-modifying osteoarthritis drug.”

Dr Dawn McGuire Chief Medical Officer, OrthoTrophix Incorporated, Oakland, US

Post hoc analysis data from the TPX-100-1 study focusing on the subset of patients with tibiofemoral osteoarthritis (n=68/93) was presented at the recent 2018 American College of Rheumatology/ Association of Rheumatology Health Professionals (ACR/ARHP) Annual Meeting. The data showed that approximately 65% of TPX-100-treated tibiofemoral osteoarthritis knees met responder criteria at 6 or 12 months or both.

Responder knees also demonstrated statistically significant improvement in cartilage thickness in both medial and lateral tibiofemoral compartments at 12 months as compared with the non-responders.

Dr Dawn McGuire, Chief Medical Officer, OrthoTrophix Incorporated, Oakland, US, who presented the data, said “These findings of the linkage between functional improvement and cartilage thickness increases support for TPX-100 as a candidate disease and structure-modifying osteoarthritis drug.”

Knee function and tibiofemoral cartilage structure changes at 12 months were analysed in 68 patients with MRI-confirmed bilateral tibiofemoral osteoarthritis (International Cartilage Repair Society (ICRS) grade 2-4) after a single series of 4 weekly intra-articular injections of TPX-100.

Responder criteria was increase in knee function as measured by knee injury and osteoarthritis outcome scores (KOOS) improvement from baseline of ≥8 points.

The TPX-100-1 study was a phase II double-blind, randomised, 12-month clinical trial originally in patients with bilateral mild-to-moderate patellofemoral osteoarthritis, across 18 US sites.

Among patients enrolled, one knee was randomly assigned to receive intra-articular TPX-100 via 4 weekly injections (20-200 mg/ injection), while the contralateral knee received identical placebo injections. The use of the contralateral knee as an internal control was designed to lessen bias due to inter-subject variation (eg: age, sex, BMI, genetic factors and activity levels).

Among TPX-100-treated patellofemoral osteoarthritis knees, n=61 (66%) met pre-defined responder criteria, with significantly more TPX-100-treated knees than placebo-exposed knees showing functional improvement at 6 or 12 months or both (p≤0.02). Overall analgesic use, including NSAIDs, declined by 68%.

Knee function improvement in knees treated with TPX-100 in the subset of patients with bilateral tibiofemoral osteoarthritis population (n=68) was similar to that in TPX-100-treated knees in all subjects (N=93), significantly in favour of TPX-100 versus placebo at 6 months, 12 months, and combined 6- and/or 12-month time points.

Intra-articular injections of up to 200 mg/ shot of TPX-100 was well tolerated by knee osteoarthritis subjects. No likely or drug-related severe adverse events were observed.

TPX-100, a peptide derived from matrix extracellular phosphoglycoprotein, has been shown to induce articular cartilage regeneration after cartilage injury in animal models and is currently being developed by OrthoTrophix, Inc.

Based on McGuire D, Segal N et al. Intra-articular TPX-100 in knee osteoarthritis: robust functional response at 6 and 12 months is associated with increased tibiofemoral cartilage thickness (abstract L18). Presented on Tuesday 23 October 2018.

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