March 2026 Research Update

This month added clearer evidence that how and when ADAMTS13 is tested can strongly affect whether TTP is recognized quickly, especially when other illnesses look similar. Two clinical studies focused on real-world testing and showed that a single early result is sometimes not enough, and that turnaround time can be a practical barrier to getting answers quickly. Together, these studies underline that ADAMTS13 testing is not just a lab number; it is also a process that can be faster or slower depending on setting and approach. [1] [2]

In ICU patients with sepsis and low platelets plus signs of red blood cell damage, repeating ADAMTS13 activity over time and combining it with a focused set of clotting and inflammation labs improved the ability to separate immune TTP from sepsis-related clotting problems. The study reported that their stepwise, time-updated approach had much better diagnostic performance than a baseline ADAMTS13 value alone, and it was designed to support a practical rule-out strategy within about 48 hours. This matters because sepsis-associated clotting and immune TTP can look alike early on, but may need different urgent responses, and this work aims to reduce missed or delayed recognition. [1]

Routine laboratory data from the Arabian Gulf and Colombia showed that only about 1 in 4 tested samples had severe ADAMTS13 deficiency, meaning many people tested for suspected TTP end up having other explanations for their symptoms. The same report highlighted that time from sample collection to results differed a lot by region, with longer turnaround times in the Arabian Gulf than in Colombia. In plain language, these data emphasize that access to timely ADAMTS13 results is uneven, and delays can complicate fast decision-making in an illness where time often matters. [2]

For patients and caregivers, these studies mainly add understanding about diagnosis rather than changing treatment choices right now. They support the idea that diagnosing TTP is sometimes a moving target, especially in the ICU or when other conditions cause similar blood test changes, and that repeating ADAMTS13 testing with other lab signals may help clarify what is happening. What remains uncertain is how well the ICU approach will work in other hospitals and health systems, because it was studied at a single center and needs outside confirmation. [1] [2]

This month, human reports largely reinforced a practical picture of TTP: it can appear in many settings, it may not look "classic" at first, and teams often rely on a combination of clinical suspicion, blood smear findings, and ADAMTS13 testing when available. Across case reports and small series, plasma exchange and immune-suppressing treatments were commonly used in immune TTP, while some TTP-like illnesses were shown to have normal ADAMTS13 and improved with supportive care. The shared message is that not every illness that looks like TTP is TTP, and telling them apart matters because the care pathway can look very different. [3] [4] [5] [6] [7]

Several reports focused on pregnancy, where TTP can overlap with other pregnancy-related clotting and blood-pressure conditions and may present without the usual neurologic or kidney symptoms people expect. One pregnant patient was diagnosed after urgent ADAMTS13 testing confirmed low activity, and she improved with plasma exchange and delivered later with a good outcome. Another report described two pregnancies where more than one thrombotic microangiopathy was thought to be happening at the same time, highlighting how difficult it can be to tell these conditions apart based on symptoms alone. [4] [8]

A small pregnancy case series from two hospitals described both congenital TTP and acquired immune TTP, showing that management can involve repeated plasma exchange and sometimes additional immune therapies when relapse occurs. The authors described rituximab use in some situations and caplacizumab use during relapse, with favorable maternal and newborn outcomes reported in these few cases. The report also pointed out real-world challenges, such as ADAMTS13 testing not always being available quickly and the limited experience with some newer drugs during pregnancy. [9]

Outside pregnancy, case reports illustrated that immune TTP can occur after surgery and can also be triggered or mimicked by infections or drugs. One postoperative patient had severe ADAMTS13 deficiency and improved after plasma exchange plus corticosteroids. In contrast, a cocaine-related thrombotic microangiopathy case had normal ADAMTS13 activity and recovered with supportive care, showing how a TTP-like picture does not always mean true TTP. [10] [6]

Other reports highlighted less typical clinical contexts that can still produce a TTP-like blood picture. One patient with Vibrio bacteremia improved rapidly after plasma exchange, but ADAMTS13 testing was not available, so the exact diagnosis could not be fully confirmed. Another case involved hereditary TTP caused by ADAMTS13 gene changes and described recurrent neurologic events along with very low ADAMTS13 activity that rose after plasma treatment and later fell again with relapse. [11] [7]

A pediatric series of immune TTP described severe ADAMTS13 deficiency with inhibitors in all four patients, with neurologic involvement in most and links to autoimmune or immune conditions in some. The authors noted that high clinical probability scores helped support early diagnosis and that treatment included plasma exchange, corticosteroids, and additional immune-modulating therapies. While small, this report adds to the picture that pediatric immune TTP often needs coordinated evaluation for possible underlying immune disease. [5]

For patients, these reports mainly matter as context: they show the range of situations where TTP or TTP-like illness can appear, including pregnancy, after surgery, in childhood, and alongside infections or drug exposure. They also reinforce that ADAMTS13 results (low versus normal) often help separate immune TTP from look-alike conditions, which can lead to very different hospital courses. Because most of this evidence is from individual cases or very small series, it cannot tell how common any specific presentation is or predict what will happen for a particular person. [4] [6] [5]

This month included early signals pointing toward two future directions: improving immune TTP outcomes with targeted add-on drugs, and designing next-generation approaches that might avoid or overcome autoantibodies. The human evidence for add-on drugs came from small real-world reports, while the most novel ideas were laboratory studies that tested mechanisms rather than patient benefit. Together, these studies expand the "how could we treat this" toolkit, but most of it remains early-stage. [12] [13] [14] [15]

In small clinical reports of acquired immune TTP, caplacizumab (a drug that blocks von Willebrand factor from grabbing platelets) was described as an add-on to plasma exchange and steroids, with patients reaching remission. One case report described a person with lupus-associated TTP who did not improve with plasma exchange and glucocorticoids but then had rapid platelet recovery and durable remission after caplacizumab plus rituximab (an immune therapy that targets B cells). These reports align in showing how clinicians may combine fast-acting clot-prevention (caplacizumab) with immune-directed therapy (such as rituximab) in difficult situations, but they do not prove how well this works in broader groups. [12] [13]

Laboratory work explored how changing the ADAMTS13 enzyme might make it more active and harder for immune TTP antibodies to block. An engineered ADAMTS13 variant (R1206K) showed higher activity against von Willebrand factor in vitro and was less strongly inhibited by antibodies from immune TTP, consistent with a more open enzyme shape. If findings like this hold up, they could eventually support designing ADAMTS13-based therapies that perform better in the presence of inhibitors, but this study did not test outcomes in people. [14]

Another lab study tested a tolerance strategy aimed at the immune cause of iTTP by using red blood cells as a delivery system to present a key ADAMTS13 piece to immune cells. The authors showed that macrophages could process this red-blood-cell-bound material and present ADAMTS13 epitope variants on HLA-DR, with stronger presentation in donors with certain HLA types. This is a feasibility step toward turning down the misdirected immune response, but it has not yet shown whether it reduces harmful T cells or prevents relapse in patients. [15]

Basic biology studies also refined the map of how von Willebrand factor and ADAMTS13-related problems might unfold at the molecular and organism level. One study assigned the structure signals of the human von Willebrand factor A2 domain and found local differences from mouse that could affect stability and unfolding, which matters because unfolding helps control where cleavage happens. A new rat model missing ADAMTS13 developed features resembling congenital TTP, including large von Willebrand factor multimers, low platelets, organ microthrombi, and kidney dysfunction, and it raised questions about the role of fetal-placental ADAMTS13 in perinatal survival. [16] [17]

For patients and caregivers, the add-on drug reports (caplacizumab, rituximab) may matter now as examples of how care is evolving in some centers, but they are based on very small numbers and cannot predict individual results. The laboratory studies are mainly future-facing: they help explain how researchers are trying to make ADAMTS13 work better despite autoantibodies, or to retrain the immune system to stop attacking ADAMTS13. What remains uncertain is which of these approaches will be safe and effective in real patients, since this month’s mechanistic studies were not clinical trials. [12] [13] [14] [15] [17]