July 2026 Research Update

Across these case reports, the main pattern was that thrombotic thrombocytopenic purpura (TTP) can be difficult to diagnose correctly because several other illnesses can closely mimic it. The reports highlighted that testing for the ADAMTS13 enzyme helped clarify the picture, but results could be normal, borderline, or low in different settings, so context and additional testing still mattered. [1] [2] [3] [4] [5]

One report from a rural emergency department described a woman whose illness was ultimately confirmed as TTP when ADAMTS13 deficiency testing came back low after transfer to a tertiary hospital, reinforcing how definitive enzyme testing may depend on access to specialized labs. She then received plasma exchange and corticosteroids and was discharged with hematology follow-up. [2]

Two reports showed how similar TTP-like features can occur even when ADAMTS13 is not severely low. In a young man with influenza A, ADAMTS13 activity was normal, yet he had a thrombotic microangiopathy (TMA) picture on blood smear and recovered after plasma exchange plus high-dose steroids; complement activation markers were also elevated. [1]

Other reports focused on look-alikes driven by another underlying disease, where sorting out the cause changed how the team interpreted the TMA picture. In a man with metastatic squamous cell carcinoma and kidney failure, a kidney biopsy showed thrombotic microangiopathy and ADAMTS13 was not severely deficient, supporting malignancy-associated TMA rather than primary TTP. [4]

A separate case described prosthetic valve endocarditis (a heart valve infection) presenting like TTP or severe clotting illness, with ADAMTS13 activity reported as 7% and no inhibitor detected, but blood cultures and heart ultrasound identified infection as a central driver. Despite multidisciplinary care, the patient developed catastrophic brain bleeding and died, underscoring how severe infection can overlap with TTP-type lab patterns. [5]

Finally, a toddler with isolated low platelets was diagnosed with hereditary TTP after very low ADAMTS13 activity and targeted ADAMTS13 gene testing found two disease-causing variants. The report noted that initial whole-exome sequencing was negative and missed key changes, showing that broad genetic tests may not always capture the specific gene changes relevant to hereditary TTP. [3]

For patients and caregivers, these reports are mainly background about why getting the diagnosis right can take more than one test, especially when infection, cancer, or a viral illness is present, or when a child has unexplained low platelets. They also show that the ADAMTS13 result alone did not look the same in every TMA situation (normal in one influenza-triggered case, severely low in hereditary TTP, low in a severe infection case, and not severely deficient in a cancer-associated kidney-predominant case). Because these are single-patient reports, they cannot tell how often each scenario happens or which approach works best overall, but they illustrate common ways TTP and its mimics can overlap.

These reports highlight that a TTP-like illness can occur in several different settings, including autoimmune disease (lupus), viral infections, advanced HIV, and during certain cancer drug combinations. A key pattern was that some patients had very low ADAMTS13 activity (supporting immune-mediated TTP), while another had preserved ADAMTS13 activity (suggesting a different type of thrombotic microangiopathy that can still look like TTP). Because these are case reports, they cannot show how often any trigger causes TTP-like illness, but they illustrate the range of real-world situations where it has been seen. [6] [7] [8] [9]

In two lupus (systemic lupus erythematosus) cases, the TTP-like presentation initially overlapped with other autoimmune blood problems, but ADAMTS13 testing later confirmed severe deficiency consistent with immune-mediated TTP. One patient also had evidence of a recent Epstein-Barr virus infection, which the authors discussed as a possible trigger for anti-ADAMTS13 antibodies in the context of lupus. Both patients improved after TTP-directed care. [6] [7]

A separate case linked a TTP-like syndrome to advanced HIV infection with other viral activity (Epstein-Barr virus and HHV-8 viremia), but ADAMTS13 activity was preserved, pointing away from classic immune-mediated TTP despite a high-risk clinical picture. The patient died during hospitalization, underscoring that TTP-like syndromes can be severe even when the underlying biology differs from ADAMTS13-related TTP. [8]

Another case described acquired TTP with an ADAMTS13 inhibitor occurring during a multiple myeloma treatment combination (bortezomib, lenalidomide, and dexamethasone). ADAMTS13 activity was undetectable and later recovered as the inhibitor became undetectable, which the authors interpreted as consistent with drug-induced acquired TTP in that setting. The patient improved with prednisolone and rituximab, without plasma exchange because the low platelet count did not keep worsening. [9]

For patients and caregivers, this set of reports mainly serves as background about possible contexts where a TTP-like illness has been reported: lupus (sometimes with other autoimmune blood conditions), certain viral infections, advanced HIV, and during specific cancer drug regimens. It also shows why ADAMTS13 testing matters for sorting true immune-mediated TTP from other look-alike clotting and blood-cell breakdown syndromes, since the same symptoms and lab patterns can have different causes. What remains uncertain from these papers is how common any of these triggers are, and which patient factors increase risk, because each report describes only one person.

Across these papers, the overall direction was consistent: immune-mediated thrombotic thrombocytopenic purpura (iTTP) care is commonly described as a combination of plasma exchange and steroids, sometimes with added medicines that target the immune system (rituximab) and clot formation (caplacizumab). The strongest support for caplacizumab in this set came from analyses of clinical trial data showing rapid effects on a blood-clotting marker, while individual case reports illustrated how multi-drug treatment and lab monitoring can track response. Important uncertainties in this group were about real-world access and reimbursement, and how much single-patient experiences apply to others. [10] [11] [12]

A Korean expert consensus described first-line treatment as prompt plasma exchange plus corticosteroids, with rituximab recommended as an add-on in immune-mediated TTP but limited by reimbursement in Korea. It also noted caplacizumab trial results showing shorter time to platelet recovery and fewer relapses, while emphasizing that caplacizumab was not available in Korea at the time of the document. The consensus highlighted bleeding of the skin and mucous membranes as an important side effect reported with caplacizumab. [10]

A post hoc pharmacodynamic (drug effect) analysis using data from the TITAN and HERCULES iTTP trials showed caplacizumab rapidly suppressed von Willebrand factor activity, a blood marker tied to platelet clumping. In the combined trial datasets, the drop in this marker by day 2 was larger with caplacizumab than with placebo, and the suppression persisted during the initial treatment period before returning toward baseline after stopping the drug. This helps explain how caplacizumab can act quickly during an acute iTTP episode, although this analysis focused on a biomarker rather than patient symptoms. [12]

One adult case report described a 46-year-old man with severe iTTP and a very high level of ADAMTS13 inhibitor antibodies who received plasma exchange, steroids, caplacizumab, and rituximab, followed by rapid blood count recovery. Repeated lab testing showed ADAMTS13 activity and inhibitor levels changing over time, supporting the idea that monitoring can document both blood recovery and immune response. Because this was one person, it cannot show that the same outcome will happen for others. [11]

For patients and caregivers, these papers mainly reinforce what is already used in many centers: plasma exchange and steroids are often described as the starting point, with other medicines sometimes added to speed recovery and reduce early complications. The trial-based analysis adds background on how caplacizumab works quickly on a clotting-related blood marker, while the case report shows how doctors may track ADAMTS13 activity and inhibitors to follow response. What remains uncertain from this set is how widely these options are available in different health systems, and how well single-patient reports predict outcomes for larger groups.

This group of papers focused on unusual or less-established approaches used in individual patients, mostly in the setting of relapse or special circumstances. The common thread was attempting to control iTTP by reducing the immune attack on ADAMTS13, measured by whether inhibitor antibodies were still detectable. Because both papers are case reports, the evidence is limited and results may not generalize. [13] [14]

In a 26-year-old man with multiple iTTP relapses, repeated episodes were managed with fresh frozen plasma transfusions plus corticosteroids without plasma exchange, and later rituximab was followed by the ADAMTS13 inhibitor becoming undetectable. The report stated the patient remained in remission for three years after rituximab, linking inhibitor clearance with longer-term disease control in this single person. The paper also noted that inhibitor testing was not straightforward in one relapse, with later testing confirming an inhibitor despite an initial negative result. [13]

A separate pediatric case report described using daratumumab as a novel therapy for acquired TTP in a child. The summary available here did not provide specific outcome numbers or side effects, so it mainly signals that some centers are exploring additional immune-targeting treatments in rare situations. As a single pediatric case, it is early and cannot define how well the approach works or how safe it is in broader use. [14]

For patients, these reports are best viewed as background on what doctors may consider in uncommon situations such as repeated relapses or when standard options are difficult to use. They suggest that tracking ADAMTS13 inhibitors over time can be one way clinicians document whether an immune-targeting medicine is having its intended effect. What remains uncertain is how often these strategies work, what risks they carry across different ages, and which patients might benefit, because the evidence here comes from only two individuals.

Across postmarketing safety reports, the overall pattern was that most reported side effects with caplacizumab were not serious, and many started soon after treatment began. Bleeding-related events were commonly reported and were consistent with what is already listed for the medicine, while some additional signals involved skin or injection-site symptoms and bruising. Because these data come from spontaneous reports, they can highlight possible problems but cannot prove how often they happen or whether the drug caused them. [15]

In a review of 1,144 US Food and Drug Administration Adverse Event Reporting System (FAERS) reports, 40.4% of the 401 reports with timing information described an event within 7 days. The most frequent reported issues included bleeding problems (such as nosebleeds, gum bleeding, stomach or intestinal bleeding, heavy menstrual bleeding, and vaginal bleeding) and these matched the product labeling. [15]

The same analysis noted additional safety signals including bruising (contusions), injection-site pain, injection-site bruising or redness, injection-site bleeding, itching, and rash. The authors also noted that decreases in the blood marker ADAMTS13 activity and platelet count were considered more likely related to the underlying acquired thrombotic thrombocytopenic purpura rather than a drug side effect, which matters because the disease itself can drive these changes. [15]

For patients and caregivers, this kind of postmarketing research mainly serves as background safety monitoring: it suggests that the most discussed risks in real-world reports are bleeding and injection-site or skin reactions, and that many reports describe early onset. What remains uncertain is how common each event truly is and how directly caplacizumab caused it, because FAERS reports do not include all treated patients and do not capture complete medical details for every report. [15]

Across these studies, outcomes in thrombotic thrombocytopenic purpura (TTP) and related clotting disorders were most strongly linked to early treatment response, kidney function after treatment, and certain early supportive care choices. Complications involved infections (including bloodstream infection) and heart problems, and the evidence ranged from moderate-sized retrospective cohorts to single-patient case reports. [16] [17] [18] [19]

In a single-center retrospective study of 47 adults hospitalized with thrombotic microangiopathy (a group of conditions that includes TTP), in-hospital mortality was 25.5%. Two factors independently pointed to higher risk of death: not achieving a treatment response and having a lower kidney filtration rate after treatment. [16]

In the same hospital study, sepsis was a major cause of death, and catheter-related bloodstream infections were noted among sepsis-related deaths. This highlights that, beyond the clotting disorder itself, severe infection can be a key complication during hospitalization. [16]

In a larger retrospective multicenter study using the TriNetX network (693 adults with lab-confirmed immune TTP defined by very low ADAMTS13 activity who received plasma exchange quickly), receiving a platelet transfusion in the first 24 hours was linked to higher 30-day mortality and more myocardial infarction (heart attack). After propensity matching, 30-day mortality was 30.0% with platelet transfusion vs 13.3% without. [17]

Two case reports add context about less obvious complications and overlap syndromes. One patient with congenital TTP (an inherited form due to ADAMTS13 gene changes) had heart imaging signs of myocardial scarring and reduced blood flow reserve without typical stress-induced blockage, suggesting possible "silent" heart involvement in some situations. [18]

Another single-patient report described a 19-year-old woman with Sjogren's syndrome who developed immune TTP and later macrophage activation syndrome (a severe inflammatory condition), emphasizing that TTP can occur alongside other immune-driven emergencies. Because this is one case, it cannot show how often this happens or reliably predict risk in others. [19]

For patients and caregivers, this set of studies suggests that near-term outcomes in TTP are closely tied to how well the illness responds early and whether kidney function improves after treatment, and that serious complications can include infection and heart events. The platelet transfusion study is most directly about short-term risk (first month) in confirmed immune TTP treated urgently, while the case reports mainly provide background about possible hidden heart involvement in congenital TTP and about rare but serious immune overlap conditions. Important uncertainties remain because two papers are single-patient reports, and the hospital cohort reflects a setting and time period with limited access to certain specialized tests and newer targeted therapies. [16] [17] [18] [19]

Across these papers, pregnancy-related clotting and low-platelet illnesses were shown to be complex, with several look-alike conditions that can affect the kidneys, placenta, and overall maternal health. A national expert conference model in France frequently changed care plans, most often by reducing or stopping treatments when the group felt true thrombotic microangiopathy was not present, while targeted treatments were reserved for a smaller subset where thrombotic thrombocytopenic purpura (TTP) or a flare of inherited TTP was suspected. [20]

In the French multidisciplinary care conference experience (76 pregnancy-associated cases), severe kidney injury was common, and TTP made up a minority of discussions (13 women, 17%), including immune-mediated and suspected inherited forms. The conference changed management in 26% of cases, with many changes described as de-escalation, and a few cases receiving recommendations for more targeted therapy, including recombinant ADAMTS-13 for suspected inherited TTP flares and one refractory immune-mediated case. [20]

One case report described a pregnant woman with suspected TTP who had refractory cardiac arrest and was supported with extracorporeal cardiopulmonary resuscitation using venoarterial ECMO as a bridge to plasma exchange, despite very low platelets. The report describes rapid improvement in heart and kidney function and full neurologic recovery with discharge home. [21]

Another case report described a woman with congenital (inherited) TTP who had limited access to repeated ADAMTS-13 testing during pregnancy, so her team used more widely available blood tests (complete blood counts and lactate dehydrogenase) to help monitor for relapse while continuing preventive plasma infusions. In that pregnancy, increasing the frequency of fresh frozen plasma later in pregnancy was paired with a healthy term delivery and no reported TTP relapse. [22]

For patients and caregivers, this set of papers mainly adds background on how pregnancy-related TTP decisions may be made in real life: many situations require sorting TTP from other pregnancy-linked clotting and blood-pressure related conditions, and kidney injury can be a major part of the picture. The strongest data here come from a real-world program showing that expert review can lead both to stepping down treatment when TTP seems unlikely and to considering ADAMTS-13-focused options when inherited or immune TTP is suspected, but it does not prove that the conference model improves outcomes. The individual case reports show what was done for one person in a severe emergency and for one person in a resource-limited setting, but they cannot predict what will happen for others. [20] [21] [22]

Across these papers, complement inhibition (such as eculizumab) was used in situations where doctors suspected complement-driven clotting injury in small blood vessels (often called atypical hemolytic uremic syndrome, aHUS) or when it was initially unclear whether the problem was aHUS versus thrombotic thrombocytopenic purpura (TTP). These are all case reports (one patient each), so they show how complement inhibition was considered in real-world situations, but they cannot prove what will happen for most people. Results were mixed: some patients improved quickly, while one child did not improve despite multiple treatments. [23] [24] [25] [26]

In a 49-year-old man with systemic lupus erythematosus who developed thrombotic microangiopathy (TMA) with features suggesting aHUS, eculizumab was followed by rapid blood count improvement within days and improvement in symptoms like shortness of breath and swelling. The report also described blood testing that supported strong activation of the complement system and showed ADAMTS13 activity was not low, which helped argue against TTP in that situation. [25]

In a 32-year-old woman with a CFH gene mutation (a complement-regulating gene) and aHUS complicated by posterior reversible encephalopathy syndrome (PRES), early eculizumab given along with plasma exchange and intensive supportive care was followed by complete neurologic recovery and later ongoing treatment with another complement inhibitor (ravulizumab). The case highlights that complement inhibition may be used urgently when aHUS causes severe complications affecting the brain, alongside other hospital-based supportive treatments. [23]

Not every suspected aHUS case improved with complement inhibition. A five-year-old boy with aHUS-like TMA and an unusually low-cell bone marrow (aplastic anemia) did not improve after plasma exchange, steroids, intravenous immunoglobulin, and eculizumab, and he died from a massive lung bleed; testing did not find anti-CFH antibodies or known complement gene changes. This single case suggests that some complex or overlapping presentations may not respond as expected, and the reasons can remain unclear. [24]

One report shows how complement inhibition can be started when the cause of TMA is uncertain, but later testing may point to TTP instead. A 55-year-old man was initially treated with eculizumab for presumed complement-mediated TMA, but later had very low ADAMTS13 activity without an inhibitor, supporting hereditary TTP; fresh frozen plasma led to blood and neurologic improvement, while long-term kidney outcome was limited by severe underlying kidney disease. This case underlines why measuring ADAMTS13 activity can matter when deciding whether complement inhibition is the right fit. [26]

For patients and caregivers, these reports mainly provide background on when doctors may consider complement inhibition: when small-vessel clotting injury appears to be driven by the complement system (including in lupus-related TMA), when genetic findings suggest complement regulation problems, or when the situation initially resembles TTP but testing later clarifies the cause. Because all evidence here is from single-patient stories, it is still uncertain how often these outcomes occur, how to predict who will respond, and what the best treatment duration is in different real-life scenarios. [23] [24] [25] [26]