Long term safety, efficacy, and patient acceptability of hyaluronic acid injection in patients with painful osteoarthritis of the knee

Interventional Radiology for Rheumatic Diseases

Imaging plays a key role in the management of rheumatological pathologies, also as guidance for diagnostic and therapeutic interventional procedures, as it can provide better accuracy and safety compared to palpation-guided interventions. Inflammatory and degenerative conditions nonresponsive to systemic treatment may benefit from intra-articular and periarticular administration of drugs, with therapeutic and symptomatic actions or providing a bridge for surgery. Desired effects include reduction of inflammation and pain and improvement of physical function of patients. Training and knowledge of indications, appropriate procedures, contraindications, and side effects are necessary to obtain maximum accuracy and safety in performing interventional procedures.

Recent Updates of Diagnosis, Pathophysiology, and Treatment on Osteoarthritis of the Knee

Osteoarthritis (OA) is a degenerative and chronic joint disease characterized by clinical symptoms and distortion of joint tissues. It primarily damages joint cartilage, causing pain, swelling, and stiffness around the joint. It is the major cause of disability and pain. The prevalence of OA is expected to increase gradually with the aging population and increasing prevalence of obesity. Many potential therapeutic advances have been made in recent years due to the improved understanding of the underlying mechanisms, diagnosis, and management of OA. Embryonic stem cells and induced pluripotent stem cells differentiate into chondrocytes or mesenchymal stem cells (MSCs) and can be used as a source of injectable treatments in the OA joint cavity. MSCs are known to be the most studied cell therapy products in cell-based OA therapy owing to their ability to differentiate into chondrocytes and their immunomodulatory properties. They have the potential to improve cartilage recovery and ultimately restore healthy joints. However, despite currently available therapies and advances in research, unfulfilled medical needs persist for OA treatment. In this review, we focused on the contents of non-cellular and cellular therapies for OA, and briefly summarized the results of clinical trials for cell-based OA therapy to lay a solid application basis for clinical research.

Therapeutic Single Compounds for Osteoarthritis Treatment

Osteoarthritis (OA) is an age-related degenerative disease for which an effective disease-modifying therapy is not available. Natural compounds derived from plants have been traditionally used in the clinic to treat OA. Over the years, many studies have explored the treatment of OA using natural extracts. Although various active natural extracts with broad application prospects have been discovered, single compounds are more important for clinical trials than total natural extracts. Moreover, although natural extracts exhibit minimal safety issues, the cytotoxicity and function of all single compounds in a total extract remain unclear. Therefore, understanding single compounds with the ability to inhibit catabolic factor expression is essential for developing therapeutic agents for OA. This review describes effective single compounds recently obtained from natural extracts and the possibility of developing therapeutic agents against OA using these compounds.

Long-term effects of intra-articular oxygen-ozone therapy versus hyaluronic acid in older people affected by knee osteoarthritis: A randomized single-blind extension study

BACKGROUND

There is little evidence on intra-articular (IA) treatment in knee osteoarthritis (KOA) and there is a lack of long-term follow-up studies.

OBJECTIVE

To assess the long-term effectiveness and safety of IA oxygen-ozone (O2O3) and hyaluronic acid (HA) in terms of functioning in KOA patients over a 31-week period.

METHODS

Patients aged ⩾ 60 years with KOA were randomly allocated to receive 4 IA knee injections (1/week) of O2O3 or HA (T0-T3) and a follow-up visit 4 weeks after the fourth injection (T4). In this extension study we assessed VAS and safety in patients with Visual Analogue Scale (VAS) ⩾ 4 at the at 6-month follow-up visit (T5), undergoing a second treatment cycle (T5-T8) and 1-month follow-up visit (T9).

RESULTS

Forty-two patients (aged 70.5 ± 5.8 years) were randomly allocated to O2O3 (n= 22) or HA group (n= 20). Twenty-three underwent another IA cycle: 12 (54.6%) in the O2O3 group and 11 (55.0%) in the HA group. Both groups showed significant reduction in VAS (p< 0.013) compared to baseline during both cycles. At follow-up visits (T4 and T9), VAS was significantly lower in the HA group (p< 0.013). There were no differences in adverse events occurrence between groups.

CONCLUSIONS

IA O2O3 might be comparable to HA in terms of effectiveness and safety in reducing pain in KOA patients, although at both follow-up visits (T4 and T9) VAS was significantly lower in the HA group.

A report on the use of a single intra-articular administration of autologous platelet therapy in a naturally occurring canine osteoarthritis model - a preliminary study

Background

Osteoarthritis (OA) represents a significant burden to societies, as it affects quality of life, performance and poses a large healthcare cost. We aimed to describe the use of a single intra-articular (IA) injection of an autologous platelet therapy in the management of osteoarthritis (OA) in a naturally occurring canine model.

Methods

Fifteen police working dogs with bilateral hip OA were treated with 3 ml of platelet concentrate per hip joint, produced with the V-PET kit. Response to treatment was measured by the Canine Brief Pain Inventory (CBPI, divided in pain interference score – PIS, and Pain Severity Score - PSS), Liverpool Osteoarthritis in Dogs (LOAD), Canine Orthopedic Index (COI, divided in four dimensions: function, gait, stiffness and quality of life - QOL) and the Hudson Visual Analogue Scale (HVAS). Seven different time points were considered: T0 (before treatment), T1 (after 15 days), T2, T3, T4, T5 and T6 (after 1, 2, 3, 4 and 5 months respectively). Results from each evaluation moment were compared with T0 with a Paired Samples T-Test, and a p < 0.05 was set.

Results

Significant differences were observed at T1 (p < 0.01 for HVAS, PSS, COI, Gait and QOL; p = 0.01 for PIS; p = 0.02 for Function; and p < 0.05 for Stiffness), T2 (p < 0.01 for PSS, PIS and Gait; p = 0.01 for COI; p = 0.02 for HVAS, Function and QOL; and p = 0.04 for Stiffness), T3 (p < 0.01 for HVAS, PSS, PIS, Function and Gait; p = 0.01 for COI; and p = 0.02 for QOL), T4 (p < 0.01 for PSS; p = 0.03 for PIS and Gait), T5 (p < 0.01 for COI, Function and Gait; p = 0.03 for PSS, PIS and Stiffness), T6 (p < 0.01 for PSS, Function and Gait; p = 0.04 for PIS; p < 0.05 for COI) and T7 (p < 0.01 for PSS, Function and Gait; p = 0.01 for COI; and p < 0.05 for PIS).

Conclusions

Autologous platelet therapy was used without apparent harm in the subjects. A single administration produced significant improvements, which lasted several months, and therefore warrants further study.

Single- and double-dose of platelet-rich plasma versus hyaluronic acid for treatment of knee osteoarthritis: A randomized controlled trial

BACKGROUND

Platelet-rich plasma (PRP) and hyaluronic acid have been shown to be useful in the treatment of knee osteoarthritis. However, investigations comparing the efficacy of these two drugs together are insufficient.

AIM

To compare the outcomes of PRP vs hyaluronic acid injections in three groups of patients with bilateral knee osteoarthritis.

METHODS

This randomized controlled trial study involved 95 patients. Thirty-one subjects received a single injection of PRP (group PRP-1), 33 subjects received two injections of PRP at an interval of 3 wk (group PRP-2) and 31 subjects received three injections of hyaluronic acid at 1-wk intervals (group hyaluronic acid). The patients were investigated prospectively at the enrollment and at 4-, 8- and 12-wk follow-up with the Western Ontario and McMaster Universities Arthritis Index (WOMAC) and Visual Analogue Scale questionnaires.

RESULTS

Percentages of patients experiencing at least a 30% decrease in the total score for the WOMAC pain subscale from baseline to wk 12 of the intervention were 86%, 100% and 0% in the groups PRP-1, PRP-2 and hyaluronic acid, respectively (P < 0.001). The mean total WOMAC scores for groups PRP-1, PRP-2 and hyaluronic acid at baseline were 63.71, 61.57 and 63.11, respectively. The WOMAC scores were significantly improved at final follow-up to 42.5, 35.32 and 57.26, respectively. The highest efficacy of PRP was observed in both groups at wk 4 with about 50% decrease in the symptoms compared with about 25% decrease for hyaluronic acid. Group PRP-2 had higher efficacy than group PRP-1. No major adverse effects were found during the study.

CONCLUSION

PRP is a safe and efficient therapeutic option for treatment of knee osteoarthritis. It was demonstrated to be significantly better than hyaluronic acid. We also found that the efficacy of PRP increases after multiple injections.

A placebo-controlled study comparing the efficacy of intra-articular injections of hyaluronic acid and a novel hyaluronic acid-platelet-rich plasma conjugate in a canine model of osteoarthritis

Background

The objective of this study was to assess the efficacy of intra-articular injections of hyaluronic acid (HA) and a novel, on-site conjugate of HA with autologous fibrinogen in platelet-rich plasma (HA-PRP) in a canine model of osteoarthritis (OA)

Methods

Twelve beagle dogs underwent a unilateral resection of the cranial cruciate ligament (CrCL) of the stifle joint. Clinical and radiographic signs of OA were confirmed in all dogs 8 weeks following CrCL resection and prior to treatment. The dogs were randomized into three groups: saline (n = 4), HA (n = 4), and HA-PRP (n = 4). Each dog received intra-articular injections of the respective substance into the affected joint at pre-determined time points. The dogs were assessed for adverse effects for 3 days after each injection and for lameness, pain, range of motion, kinetics, and radiographic OA severity prior to treatment and 3 months after injection. OA severity as determined by radiographic examination was not significantly different among the groups at any time point. The dogs were then humanely euthanatized and the stifle joint assessed by gross and histological examinations.

Results

Dogs treated with four weekly injections of HA or two biweekly injections of HA-PRP were significantly (p < 0.05) better than dogs treated with four weekly injections of saline at 2-, 4-, and 12-week time points based on a comfortable range of motion (CROM) and clinical lameness score. Gait analysis measuring symmetry and weight distribution on pressure sensor walkway showed significantly (p < 0.05) improved limb function for dogs treated with HA and HA-PRP compared with dogs treated with saline yet with better clinical outcome for the HA-PRP-treated group at 12 and 20 weeks follow-up. Gross and histological analysis of synovium and articular cartilage demonstrated significant (p < 0.05) improvement by both treatments groups compared to controls. There was however significantly (p < 0.05) less damage to the cartilage in the HA-PRP group compared to the HA-treated group.

Conclusions

These data suggest that while injection of HA and HA-PRP may be sufficient for short-term amelioration of the symptoms associated with OA, treatment with HA-PRP conjugates may be superior, providing significantly better long-term cartilage preservation.

Intra-articular, single-shot co-injection of hyaluronic acid and corticosteroids in knee osteoarthritis: A randomized controlled trial

The aim of the present study was to investigate whether the co-injection of hyaluronic acid (HA) and corticosteroids (CS) was superior to HA alone in the treatment of knee OA. A total of 120 participants with symptomatic knee OA were recruited and formed the intention-to-treat population for a 6-month follow-up. In the HA group, patients received a single-shot injection of 4 ml HA. In the HA&CS group, patients received a co-injection of 3 ml compound betamethasone solution and 4 ml HA. Visual analog scale (VAS), Western Ontario and McMaster University Osteoarthritis Index (WOMAC) and knee flexion motion were assessed as primary outcomes. Patients in the HA&CS group exhibited better pain relief and knee function at the time points of week 1, month 1 and month 3 (P<0.05). For the last follow-up at month 6, the values did not differ significantly between these two groups. Patients in both groups exhibited improvement in pain, knee function, and range of motion following injection. For the final follow-up at month 6, the mean VAS score, WOMAC score and knee flexion motion were still superior to that prior to treatment, but the values did not differ significantly. The co-injection of HA and CS provided a rapid improvement in pain relief, knee function, and range of motion, but did not differ significantly from that of HA alone in the long term effect.

Hyaluronic Acid

In recent times, the field of tissue engineering and regenerative medicine (TERM) has considerably increased the extent of therapeutic strategies for clinical application in orthopedics. However, TERM approaches have its rules and requirements, in the respect of the biologic response of each tissue and bioactive agents which need to be considered, respected, and subject of ongoing studies. Different medical devices/products have been prematurely available on the market and used in clinics with limited success. However, other therapeutics, when used in a serious and evidence-based approach, have achieved considerable success, considering the respect for solid expectations from doctors and patients (when properly informed).Orthobiologics has appeared as a recent technological trend in orthopedics. This includes the improvement or regeneration of different musculoskeletal tissues by means of using biomaterials (e.g., hyaluronic acid), stem cells, and growth factors (e.g., platelet-rich plasma). The potential symbiotic relationship between biologic therapies and surgery makes these strategies suitable to be used in one single intervention.However, herein, the recent clinical studies using hyaluronic acid (HA) in the treatment of orthopedic conditions will mainly be overviewed (e.g., osteochondral lesions, tendinopathies). The possibilities to combine different orthobiologic agents as TERM clinical strategies for treatment of orthopedic problems will also be briefly discussed.

A Fatal Sepsis Caused by Hyaluronate Knee Injection: How Much the Medical History and the Informed Consent Might Be Important?

The incidence of Osteoarthritis (OA) is gradually increasing worldwide due to two main reasons: longer life expectation and increased functional demand. Several treatment options have been proposed for this disease. Conservative treatment has the goal to improve the quality of life, reduce pain, and prevent the progression of the disease. Hyaluronate viscosupplementation is one of the most used infiltrative treatments for OA, but, despite its common use, clinical efficacy is still under question. Though adverse reactions for this medical option are actually rare, septic arthritis is a very scaring complication. We present a case report of a 59-year-old man who has been submitted to only one knee hyaluronate injection and consequently reported a severe septic arthritis and systemic sepsis, which lead to the death of the patient. We recommend producing correct guidelines for a clean aseptic procedure of injection to obtain proper consensus from the patient and to pay attention to his clinical history and comorbidities before acting any kind of invasive treatment, including joint injection.

Anaesthetics, steroids and platelet-rich plasma (PRP) in ultrasound-guided musculoskeletal procedures

This review aims to evaluate the role of anaesthetics, steroids and platelet-rich plasma (PRP) employed with ultrasound-guided injection in the management of musculoskeletal pathology of the extremities. Ultrasound-guided injection represents an interesting and minimally invasive solution for the treatment of tendon and joint inflammatory or degenerative diseases. The availability of a variety of new drugs such as hyaluronic acid and PRP provides expansion of the indications and therapeutic possibilities. The clinical results obtained in terms of pain reduction and functional recovery suggest that the use of infiltrative procedures can be a good therapeutic alternative in degenerative and inflammatory joint diseases.

Hyaluronic acid compared with corticosteroid injections for the treatment of osteoarthritis of the knee: a randomized control trail

Background

Osteoarthritis (OA) is the most common chronic condition of the joints that takes place when the cartilage or a low friction surface between joints breaks down which leads to pain, stiffness and swelling. The purpose of the present study was to evaluate the therapeutic effect of intra-articular hyaluronic acid (HA) in comparison to corticosteroids (CS) for knee osteoarthritis.

Methods

140 patients with knee osteoarthritis, who were followed for 3 months, were randomized to receive intra-articular injection of either hyaluronic acid or corticosteroid. By receiving one injection of drug during the enrollment in the study, the patients were treated. With the Western Ontario and McMaster University Osteoarthritis Index (WOMAC), Knee injury and Osteoarthritis Outcome Score (KOOS), and the visual analog pain scale, an independent, blinded evaluator assessed the patients three times.

Results

The mean age of the patients in the corticosteroid group were 57 ± 1.9 years and in Hyaluronic acid group were 58.5 ± 8.3 years. WOMAC score represented that pain and stiffness did not improve in neither groups at any time points after intervention (P > 0.05). KOOS score suggested that symptoms improved after 3 months in both CS and HA groups. Besides, daily activity improved in both groups (P < 0.05).

Conclusions

As a conclusion, it is argued that the most important difference between the two intervention groups is the duration of effectiveness. HA is suggested to be superior in the duration of pain relief when compared to CS. We can propose that HA can be administered every 3 months intra-articular for knee joint OA. Therefore, when CS has to be injected every 2 months, it will be more convenient to use HA.

Hyaluronic Acid Injections Are Associated with Delay of Total Knee Replacement Surgery in Patients with Knee Osteoarthritis: Evidence from a Large U.S. Health Claims Database

BACKGROUND

The growing prevalence of osteoarthritis (OA) and the medical costs associated with total knee replacement (TKR) surgery for end-stage OA motivate a search for agents that can delay OA progression. We test a hypothesis that hyaluronic acid (HA) injection is associated with delay of TKR in a dose-dependent manner.

METHODS AND FINDINGS

We retrospectively evaluated records in an administrative claims database of ~79 million patients, to identify all patients with knee OA who received TKR during a 6-year period. Only patients with continuous plan enrollment from diagnosis until TKR were included, so that complete medical records were available. OA diagnosis was the index event and we evaluated time-to-TKR as a function of the number of HA injections. The database included 182,022 patients with knee OA who had TKR; 50,349 (27.7%) of these patients were classified as HA Users, receiving ≥1 courses of HA prior to TKR, while 131,673 patients (72.3%) were HA Non-users prior to TKR, receiving no HA. Cox proportional hazards modelling shows that TKR risk decreases as a function of the number of HA injection courses, if patient age, gender, and disease comorbidity are used as background covariates. Multiple HA injections are therefore associated with delay of TKR (all, P < 0.0001). Half of HA Non-users had a TKR by 114 days post-diagnosis of knee OA, whereas half of HA Users had a TKR by 484 days post-diagnosis (χ2 = 19,769; p < 0.0001). Patients who received no HA had a mean time-to-TKR of 0.7 years; with one course of HA, the mean time to TKR was 1.4 years (χ2 = 13,725; p < 0.0001); patients who received ≥5 courses delayed TKR by 3.6 years (χ2 = 19,935; p < 0.0001).

CONCLUSIONS

HA injection in patients with knee OA is associated with a dose-dependent increase in time-to-TKR.

Oral intake of a liquid high-molecular-weight hyaluronan associated with relief of chronic pain and reduced use of pain medication: results of a randomized, placebo-controlled double-blind pilot study

The goal for this study was to evaluate the effects of daily oral intake of a consumable liquid fermentate containing high-molecular-weight hyaluronan, as well as to perform a basic evaluation of safety and tolerability. A randomized, double-blind placebo-controlled study design was used to examine the effects of oral intake of hyaluronan on chronic pain conditions. Safety assessment included a complete blood count with differential, blood chemistry and electrocardiogram. The study duration was 4 weeks, where three tablespoons (45 mL) product or placebo was ingested during the first 2 weeks, and two tablespoons (30 mL) was consumed during the last 2 weeks. Seventy-eight people between the age of 19 and 71 years enrolled, and 72 people completed the study. Statistical analysis was performed using the two-tailed independent t-test for between-group significance and using the paired t-test for within-group significance. A reduction in pain scores was seen after 2 weeks of consumption of both placebo (P<.1) and active (P<.065) product; the reduction was more pronounced in the group consuming the active test product. Using "within-subject" analysis, a highly significant reduction in chronic pain scores was seen after 2 weeks of consumption of three tablespoons of active product (P<.001), whereas only a mild nonsignificant reduction in pain scores was seen in the placebo group. During the reduced intake for the last 2 weeks of study participation, pain scores showed a slight increase. During the last 2 weeks, a significant increase in the quality of sleep (P<.005) and level of physical energy (P<.05) was seen. The pain reduction during the initial 2 weeks was associated with significant reduction in the use of pain medication (P<.05). Consumption of an oral liquid formula containing high-molecular-weight hyaluronan was associated with relief of chronic pain.

Knee Osteoarthritis Injection Choices: Platelet- Rich Plasma (PRP) Versus Hyaluronic Acid (A one-year randomized clinical trial)

INTRODUCTION

Knee osteoarthritis (OA) is the most common articular disease. Different methods are used to alleviate the symptoms of patients with knee OA, including analgesics, physical therapy, exercise prescription, and intra-articular injections (glucocorticoids, hyaluronic acid [HA], etc). New studies have focused on modern therapeutic methods that stimulate cartilage healing process and improve the damage, including the use of platelet-rich plasma (PRP) as a complex of growth factors. Due to the high incidence of OA and its consequences, we decided to study the long-term effect of intraarticular injection of PRP and HA on clinical outcome and quality of life of patients with knee OA.

METHOD

This non-placebo-controlled randomized clinical trial involved 160 patients affected by knee OA, grade 1-4 of Kellgren-Lawrence scale. In the PRP group (n = 87), two intra-articular injections at 4-week interval were applied, and in the HA group (n = 73), three doses of intra-articular injection at 1-week interval were applied. All patients were prospectively evaluated before and at 12 months after the treatment by Western Ontario and McMaster Universities Arthritis Index (WOMAC) and SF-36 questionnaires. The results were analyzed using SPSS 16.1 software (RCT code: IRCT2014012113442N5).

RESULTS

At the 12-month follow-up, WOMAC pain score and bodily pain significantly improved in both groups; however, better results were determined in the PRP group compared to the HA group (P < 0.001). Other WOMAC and SF-36 parameters improved only in the PRP group. More improvement (but not statistically significant) was achieved in patients with grade 2 OA in both the groups.

CONCLUSION

This study suggests that PRP injection is more efficacious than HA injection in reducing symptoms and improving quality of life and is a therapeutic option in select patients with knee OA who have not responded to conventional treatment.

Intraarticular injections (corticosteroid, hyaluronic acid, platelet rich plasma) for the knee osteoarthritis

Osteoarthritis (OA) is a complex “whole joint” disease pursued by inflammatory mediators, rather than purely a process of “wear and tear”. Besides cartilage degradation, synovitis, subchondral bone remodeling, degeneration of ligaments and menisci, and hypertrophy of the joint capsule take parts in the pathogenesis. Pain is the hallmark symptom of OA, but the extent to which structural pathology in OA contributes to the pain experience is still not well known. For the knee OA, intraarticular (IA) injection (corticosteroids, viscosupplements, blood-derived products) is preferred as the last nonoperative modality, if the other conservative treatment modalities are ineffective. IA corticosteroid injections provide short term reduction in OA pain and can be considered as an adjunct to core treatment for the relief of moderate to severe pain in people with OA. IA hyaluronic acid (HA) injections might have efficacy and might provide pain reduction in mild OA of knee up to 24 wk. But for HA injections, the cost-effectiveness is an important concern that patients must be informed about the efficacy of these preparations. Although more high-quality evidence is needed, recent studies indicate that IA platelet rich plasma injections are promising for relieving pain, improving knee function and quality of life, especially in younger patients, and in mild OA cases. The current literature and our experience indicate that IA injections are safe and have positive effects for patient satisfaction. But, there is no data that any of the IA injections will cause osteophytes to regress or cartilage and meniscus to regenerate in patients with substantial and irreversible bone and cartilage damage.

A Patient with Fatal Necrotizing Fasciitis following the Use of Intra-Articular Sodium Hyaluronate Injections: A Case Report

Introduction. Osteoarthritis, a degenerative joint disease, is a key cause of disability around the world and an ever-growing public health concern. Intra-articular hyaluronic acid viscosupplementation is used as a conservative option for osteoarthritis knee pain relief (McArthur et al., 2012; Hootman and Helmick, 2006; Huang el al., 2011). In general, the literature has shown an excellent safety profile for this treatment modality (McArthur et al., 2012; Clegg et al., 2013; Hammesfahr et al., 2003; Neustadt et al., 2005; Cohen et al., 2008; Neustadt, 2003; Jüni et al., 2007; Peterson and Hodler, 2011). Case Presentation. In this report, we describe a case of a woman who had received multiple sodium hyaluronate injections and developed severe necrotizing fasciitis near the injection site. Conclusion. We recommend that clear guidelines for clean technique be put in place for use with sodium hyaluronate injections and consideration of full sterile technique in immunosuppressed patients.

A posteriori comparison of natural and surgical destabilization models of canine osteoarthritis

For many years Canis familiaris, the domestic dog, has drawn particular interest as a model of osteoarthritis (OA). Here, we optimized the dog model of experimental OA induced by cranial cruciate ligament sectioning. The usefulness of noninvasive complementary outcome measures, such as gait analysis for the limb function and magnetic resonance imaging for structural changes, was demonstrated in this model. Relationships were established between the functional impairment and the severity of structural changes including the measurement of cartilage thinning. In the dog model of naturally occurring OA, excellent test-retest reliability was denoted for the measurement of the limb function. A criterion to identify clinically meaningful responders to therapy was determined for privately owned dogs undergoing clinical trials. In addition, the recording of accelerometer-based duration of locomotor activity showed strong and complementary agreement with the biomechanical limb function. The translation potential of these models to the human OA condition is underlined. A preclinical testing protocol which combines the dog model of experimental OA induced by cranial cruciate ligament transection and the Dog model of naturally occurring OA offers the opportunity to further investigate the structural and functional benefits of disease-modifying strategies. Ultimately, a better prediction of outcomes for human clinical trials would be brought.