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DEAR DR. ROACH: I was really interested in reading your recent columns on rheumatoid arthritis (RA) and other inflammatory arthritic conditions. I’ve taken most medications that you mentioned in your column. However, there’s a product called PS372424 that’s been in research since 2014, yet no medical rheumatology departments have even involved patients in taking it. This is a nontoxic alternative to all the medications that are given to children and adults for inflammatory arthritic diseases.
I’m in the United Kingdom, but I’d be really interested to hear what our American doctor friends think about pursuing the use of PS372424. -- M.T.
ANSWER: PS372424 is a small molecule that modulates the effect of a receptor called CXCR3, which has complex actions on the movement and activity of immune cells. This especially goes for T4 and T8 cells, but many other cells as well.
PS372424 itself never entered clinical trials, as it was designed as a tool to study the CXCR3 system — not as a drug for clinical use. (PS372424 stimulates CXCR3, and the drugs that have entered clinical trials block the effect of CXCR3.) Only one of the compounds that block the effect of CXCR3 entered clinical trials (AMG487), but unfortunately, it didn’t show enough of a clinical benefit to get beyond early trials.
It’s common for new discoveries (like the CXCR3 receptor’s effects on the chemokine system) to lead to optimism about major medical advances. Unfortunately, the path from basic science knowledge to new clinical treatments is longer and more arduous than we’d like it to be. It can still be hoped that a better understanding of this incredibly complex system with multiple redundancies could lead to effective treatments.
There are currently many effective treatments for RA that are much safer than they used to be and less dangerous than leaving RA untreated.
DEAR DR. ROACH: I recently read that in order to have calcium absorbed by the bones (and not deposited in our arteries), one needs to take a vitamin D3 supplement that also includes K2. Is this correct? I’ve been taking a 2,000 IU D3 pill four to five times a week, and I’ve been making sure that there’s some healthy fat in the same meal to increase the absorption of the calcium. I can’t tolerate calcium supplements and want to ensure that my bones are receiving calcium. -- D.M.
ANSWER: In theory, K2 helps direct calcium that gets absorbed from your intestines into your bones (where you want it), not into the blood vessels (where you don’t, as this can accelerate blockages). Unfortunately, clinical trials from Japan only showed a very modest benefit (1%) in bone density improvement and no reduction in the risk of fractures. Trials performed in the United States didn’t show a benefit at all.
A very recent study on vitamin K2 showed a reduction in coronary artery calcium, but no reduction in heart attacks, strokes, or the risk of death. It may be that larger trials are needed to show a benefit, but the available evidence suggests that whatever benefit there might be is likely to be small.
You’re quite right that a small amount of healthy fat improves the absorption of calcium, but large amounts of unhealthy fat (saturated fats like palm oil or those found in meat) actually decrease absorption.
Many people are intolerant of the standard calcium supplement, calcium carbonate. Calcium citrate (Citracal and others) tends to be better tolerated, especially when taken several times a day in smaller doses. Dietary calcium (dairy products, fortified juices, and small fish with bones) is still generally preferred to reduce the risk of kidney stones.
Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu. (c) 2026 North America Syndicate Inc.
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