Obesity Is Associated with Altered Tumor Metabolism in Metastatic Melanoma

PURPOSE

Overweight/obese (OW/OB) patients with metastatic melanoma unexpectedly have improved outcomes with immune checkpoint inhibitors (ICI) and BRAF-targeted therapies. The mechanism(s) underlying this association remain unclear, thus we assessed the integrated molecular, metabolic, and immune profile of tumors, as well as gut microbiome features, for associations with patient body mass index (BMI).

EXPERIMENTAL DESIGN

Associations between BMI [normal (NL < 25) or OW/OB (BMI ≥ 25)] and tumor or microbiome characteristics were examined in specimens from 782 patients with metastatic melanoma across 7 cohorts. DNA associations were evaluated in The Cancer Genome Atlas cohort. RNA sequencing from 4 cohorts (n = 357) was batch corrected and gene set enrichment analysis (GSEA) by BMI category was performed. Metabolic profiling was conducted in a subset of patients (x = 36) by LC/MS, and in flow-sorted melanoma tumor cells (x = 37) and patient-derived melanoma cell lines (x = 17) using the Seahorse XF assay. Gut microbiome features were examined in an independent cohort (n = 371).

RESULTS

DNA mutations and copy number variations were not associated with BMI. GSEA demonstrated that tumors from OW/OB patients were metabolically quiescent, with downregulation of oxidative phosphorylation and multiple other metabolic pathways. Direct metabolite analysis and functional metabolic profiling confirmed decreased central carbon metabolism in OW/OB metastatic melanoma tumors and patient-derived cell lines. The overall structure, diversity, and taxonomy of the fecal microbiome did not differ by BMI.

CONCLUSIONS

These findings suggest that the host metabolic phenotype influences melanoma metabolism and provide insight into the improved outcomes observed in OW/OB patients with metastatic melanoma treated with ICIs and targeted therapies. See related commentary by Smalley, p. 5.

Impact of Aurora kinase A and B expression on response to neoadjuvant chemotherapy and patient outcome in muscle-invasive bladder cancer (MIBC)

393

Background: Identification of robust biomarkers that predict likelihood of benefit from neoadjuvant chemotherapy (NAC) in patients with MIBC remains an unmet need. Previous studies have implicated tumor overexpression of aurora kinases A (AURKA) and B (AURKB) as a mechanism of chemo-resistance. Because overexpression of AURKA has also emerged as a potential biomarker for detection of high-risk urothelial carcinoma, we sought to characterize the expression of AURKA, AURKB with clinical outcomes in MIBC patients who received NAC and to test the hypothesis that tumor overexpression of AURKA and AURKB would predict for residual MIBC. Methods: 47 patients with MIBC who received NAC prior to cystectomy were retrospectively identified. Immunohistochemistry for AURKA and AURKB was performed on pre-treatment diagnostic transurethral resection of bladder tumors and matched cystectomy specimens. Logistic regression models were estimated to determine the impact of pre-NAC expression on pathologic staging at cystectomy. Receiver Operator Characteristic curves (ROC) were calculated to assess diagnostic predictive ability of AURKA and AURKB. AURKA and AURKB were assessed for association with relapse-free survival (RFS) and overall survival (OS) using Kaplan-Meier techniques and Cox proportional hazards models. Results: 22 of 47 [46.8%] patients had residual muscle-invasive (ypT2-4) urothelial carcinoma after NAC. Neither baseline tumor expression of AURKA (ROC = 0.54, p = 0.71) nor AURKB (ROC = 0.46, p = 0.98) predicted for ypT2-4 status. However, baseline expression of AURKA above the 75th percentile for this cohort, determined by the percentage of tumor cells positive, was associated with an inferior RFS, [HR = 3.79, [1.40, 10.26] p = 0.005] and OS, [HR = 5.84, [2.14, 15.98], p < 0.001]. Similar trends for worse survival outcomes were also observed for high AURKB levels. Conclusions: Although baseline tumor AURKA and AURKB expression did not predict for pathologic residual MIBC after NAC, high expression of AURKA and AURKB predicted for inferior RFS and OS. Further evaluation of AURKA and AURKB as potential biomarkers and therapeutic targets in MIBC is warranted.

Discordance of high PD-L1 expression in primary and metastatic urothelial carcinoma lesions

Immune checkpoint inhibitors (ICI) targeting PD-(L)1 are effective in select patients with advanced urothelial carcinoma (UC). High PD-L1 expression enriches for response to ICIs; however, the predictive value of PD-L1 expression is limited, which may be due in part to dynamic expression of PD-L1 in the tumor environment. We sought to characterize PD-L1 expression in primary UC and paired metastatic lesions to gain insight into the potential discordance of tumor PD-L1 expression during the metastatic process.

MATERIALS AND METHODS

Immunohistochemical staining for PD-L1 using the SP-142 antibody was performed on primary tumors and matched metastatic specimens in 77 evaluable subjects with advanced UC. Immunohistochemical staining was scored for the percentage of cells positive (<5%, ≥5%) in tumor cell (TC) and immune cell (IC) compartments. Correlation of PD-L1 expression in TCs and ICs was estimated using Spearman's correlation coefficients (rho, ρ). Cohen's kappa statistics (κ) were utilized to assess the agreement in PD-L1 expression between groups.

RESULTS

High (≥5%) PD-L1 expression in primary and metastatic biopsies, respectively, was observed in 6.0% and 7.7% of TCs and in 14.5% and 11.5% of ICs. IC PD-L1 expression in primary tumors was not correlated with IC PD-L1 expression in paired metastatic lesions (ρ = 0.05, P = 0.67) and there was poor agreement in high expression rates between primary and metastatic lesions in the IC compartment (κ= 0.086).

CONCLUSION

High PD-L1 IC expression is temporally and spatially discordant between primary and metastatic UC lesions. Future studies of PD-(L)1 targeted therapies in patients with metastatic UC may benefit from use of fresh biopsies of metastatic lesions to define PD-L1 expression when feasible.

The Feasibility of Repetitive Courses of High-Dose Continuous Intravenous Infusion Interleukin-2 and Subcutaneous Alpha-Interferon with Polychemotherapy in Advanced Malignant Melanoma

Aims and background

A Phase I study of repetitive courses of chemotherapy (carmustine, cis-platinum, dacarbazine) and immunotherapy (continuous intravenous infusion recombinant interleukin-2 (rIL-2) and subcutaneous (sc) alpha-interferon 2b) plus tamoxifen was performed in order to establish a more efficaciuous way to sequence this kind of treatment for advanced malignant melanoma.

Study design

Patients who had measurable metastatic melanoma, a Karnofsky performance status ≥ 80, and no clinically significant hematologic or cardiac disfunction were considered eligible. Treatment consisted of BCNU, 150 mg/m2 i.v. day 1 in alternating cycles; DTIC, 220 mg/m2 i.v. days 1, 2 and 3; CDDP, 25 mg/m2 i.v. days 1, 2 and 3; tamoxifen 10 mg twice/day per os continuously; rIL-2, 18 × 106 IU/m2/day continuous i.v. infusion days 5-8 (96 h) and days 19-22 (96 h); alpha-interferon (IFN) s.c. 3 × 106 U day 12, 6 × 106 U day 14, 9 × 106 U days 16, 19, 21, 23, 26, and 28 (from cycle 2, 9 × 106 U days 2, 5, 7, 9, 12, 14, 16, 19, 21, 23, 26, and 28). Two consecutive cycles were planned until response evaluation.

Results

Three patients were treated according with the protocol; none of them was able to respect the planned dose-intensity schedule. The given dose intensity/planned dose intensity ratios were as follows: DTIC, 0.74 (range, 0.70-0.80); CDDP, 0.77 (0.72-0.80); BCNU, 0.77 (0.72-0.80); rIL-2, 0.65 (0.36-0.80); alpha-IFN, 0.01 (0-0.03); tamoxifen, 1.0. Systemic side effects of rIL-2 and myelotoxicity were the main reasons for treatment delay and/or dose-reduction, and for the long period of hospital care.

Conclusions

We conclude that the treatment schedule is not feasible. However, since we believe that combined chemo-immunotherapy is a potentially active treatment in metastatic malignant melanoma, we have modified it in order to make it more feasible and consequently efficacious.

Discordance rate of PD-L1 expression between primary and metastatic lesions in urothelial carcinoma (UC)

493

Background: Immune checkpoint inhibitors (ICI) targeting PD-1 or PD-L1 are effective in select patients with advanced UC. High PD-L1 expression enriches for response to ICIs; however, the predictive value of PD-L1 expression is limited, which may be due in part to dynamic expression of PD-L1 in the tumor environment. We sought to characterize PD-L1 expression in primary UC and paired metastatic lesions to gain insight into the potential temporal discordance of tumor PD-L1 expression during the metastatic process. Methods: Immunohistochemical (IHC) staining for PD-L1 using the SP-142 antibody was performed on primary tumors and matched metastatic specimens in 83 patients with advanced UC. IHC staining was scored for the percentage of cells positive ( < 5%, ≥5%) in tumor cell (TC) and immune cell (IC) compartments. Correlation of PD-L1 expression in TCs and ICs was estimated using Spearman’s correlation coefficients (ρ). Cohen’s kappa statistics (κ) were utilized to assess the agreement in PD-L1 expression between groups. Results: High (≥5%) PD-L1 expression in primary and metastatic biopsies, respectively, was observed in 6.1% and 14.6% of TCs and in 7.8% and 11.7% of ICs. High co-expression of PD-L1 in both TC and IC compartments was infrequent in primary and metastatic lesions (3.6% and 2.6%, respectively). PD-L1 expression in TCs was positively correlated with PD-L1 expression in ICs in primary tumors (ρ = 0.47) and in metastatic lesions (ρ = 0.27). TC PD-L1 expression in primary tumors was correlated with TC PD-L1 expression in paired metastatic lesions (ρ = 0.44) but there was minimal agreement in high expression rates between primary and metastatic lesions in the TC compartment (κ = 0.147). IC PD-L1 expression in primary tumors was not correlated with IC PD-L1 expression in paired metastatic lesions (ρ = 0.05) and there was poor agreement in high expression rates between primary and metastatic lesions in the IC compartment (κ = 0.086). Conclusions: High PD-L1 IC expression is temporally discordant between primary and metastatic UC lesions. Future studies of PD-1/PD-L1 targeted therapies in patients with metastatic UC should utilize recent biopsies of metastatic lesions to define PD-L1 expression when feasible.

Duvelisib treatment is associated with altered expression of apoptotic regulators that helps in sensitization of chronic lymphocytic leukemia cells to venetoclax (ABT-199)

Duvelisib, an oral dual inhibitor of PI3K-δ and PI3K-γ, is in phase III trials for the treatment of chronic lymphocytic leukemia (CLL) and indolent non-Hodgkin's lymphoma. In CLL, duvelisib monotherapy is associated with high iwCLL (International Workshop on Chronic Lymphocytic Leukemia) and nodal response rates, but complete remissions are rare. To characterize the molecular effect of duvelisib, we obtained samples from CLL patients on the duvelisib phase I trial. Gene expression studies (RNAseq, Nanostring, Affymetrix array and real-time RT-PCR) demonstrated increased expression of BCL2 along with several BH3-only pro-apoptotic genes. In concert with induction of transcript levels, reverse phase protein arrays and immunoblots confirmed increase at the protein level. The BCL2 inhibitor venetoclax induced greater apoptosis in ex vivo-cultured CLL cells obtained from patients on duvelisib compared with pre-treatment CLL cells from the same patients. In vitro combination of duvelisib and venetoclax resulted in enhanced apoptosis even in CLL cells cultured under conditions that simulate the tumor microenvironment. These data provide a mechanistic rationale for testing the combination of duvelisib and venetoclax in the clinic. Such combination regimen (NCT02640833) is being evaluated for patients with B-cell malignancies including CLL.

Abstract 2657: Elevated level of BCL-2 is the primary target for inhibition during duvelisib (IPI-145) therapy: ABT-199 neutralizes the resistance mechanism in chronic lymphocytic leukemia

Inhibition of BTK by ibrutinib, PI3K-delta with idelalisib, or PI3K-delta and gamma with duvelisib (IPI-145), all components of B-cell receptor (BCR) pathway, has significantly improved the treatment outcome in chronic lymphocytic leukemia (CLL) via disrupting the interactions with microenvironment. Though BCR network inhibitors induce durable remission in the majority of CLL patients, a proportion of patients that initially respond to treatment develop resistance or some show maintained lymphocytosis in the blood. Identifying and overcoming resistance mechanisms will be crucial for the most effective combinatorial use of these agents. Duvelisib is an orally bioavailable, highly potent small molecule inhibitor of p110δ and p110γ with KD values of 0.023 nM and 0.24 nM, respectively. Preclinical investigations with duvelisib overcame signals from PI3K/AKT/S6 pathway and promoted apoptosis in primary CLL cells (Balakrishnan et al, ASH 2013). Duvelisib is currently in a phase III trial in CLL. During first phase I study, we performed molecular investigations. PBMCs collected from CLL patients from Phase I study of duvelisib treatment (Pre/Day 0 and Post/Day 28) were subjected to RPPA analysis (n = 7). Interestingly, of the 141 proteins analyzed, Bcl-2 was maximally and significantly elevated in Day 28 samples (mean fold + SEM: 1.7 + 0.2; p = 0.015), suggesting that this could be in part the mechanism involved in resistance during therapy. Further analysis of protein expression by immunoblotting confirmed that Bcl-2 protein was elevated in post-treatment samples (1.3 + 0.1; p = 0.086; n = 7). This was in conjunction with elevated levels of Bcl-2 transcripts analyzed by mRNA array (TaqMan Human Apoptosis - 93 genes) assay (3.0 + 0.4; p = 0.002) and RT-PCR (1.9 + 0.2; p = 0.003), while other anti-apoptotic genes (Bfl-1, Mcl-1, Bcl-w Bcl-g, Bcl-b, Bcl-xL) were unchanged. Importantly, ex-vivo incubations of pre- and post- duvelisib samples with 3 nM ABT-199, a highly selective clinically promising Bcl-2 protein antagonist, induced significantly greater apoptosis in post-therapy samples (79%) in comparison to pre-treatment (58%) samples suggesting that Bcl-2 is the primary target for inhibition during duvelisib intake (n = 5; p = 0.041). In addition, duvelisib induced sensitivity on ex-vivo post- duvelisib clinical samples (n = 15) was specifically towards ABT-199 and produced significantly more apoptosis in the presence of ABT-199 (45%, p&lt;0.0001; 3 nM) compared to other clinically-relevant agents such as ibrutinib (1%, p = 0.10; 10 μM), idelalisib (4% p = 0.05; 10 μM) or ABT-737 (16%, p = 0.0002; 10 nM). We report that elevated Bcl-2 level is the primary target for inhibition during duvelisib therapy and thereby combination with ABT-199 could be a rational approach to overcome the resistance mechanism.

Citation Format: Viralkumar M. Patel, Kumudha Balakrishnan, Renato Guerrieri, William Wierda, Susan O'Brien, Varsha Gandhi. Elevated level of BCL-2 is the primary target for inhibition during duvelisib (IPI-145) therapy: ABT-199 neutralizes the resistance mechanism in chronic lymphocytic leukemia. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2657. doi:10.1158/1538-7445.AM2015-2657

Effectiveness of the photochemical reflectance index to track photosynthetic activity over a range of forest tree species and plant water statuses

In this study, we investigated the potential of the photochemical resistance index (PRI) to track photosynthetic activity under water stress conditions by measuring PRI, leaf fluorescence, the xanthophyll cycle and photosynthetic activity in different forest tree species subjected to progressive drought. The PRI declined with pre-dawn water potential and a significant relationship between PRI and the xanthophyll de-epoxidation state (DEPS) was observed, although with large interspecific variability in the sensitivity of PRI to changes in DEPS. For single tree species, a strong relationship was observed on either PRI light saturated photosynthesis or PRI maximum photochemical efficiency of PSII (ΔF/Fm'); a larger variability in both relationships was apparent when data from different species were pooled together. However, an improved correlation was shown only in the former relationship by plotting the ΔPRI (dawn PRI minus the midday PRI values). Thus, we conclude that PRI is able to provide a good estimate of maximum CO2 assimilation at saturating light and ΔF/Fm' for single tree species, despite the severe drought conditions applied. PRI should be applied more cautiously when dealing with multispecific forests because of confounding factors such as the strong interspecific differences in the initial value of PRI and in the sensitivity of PRI to changes in DEPS in response to drought.

alpha-Tocopheryl succinate promotes selective cell death induced by vitamin K3 in combination with ascorbate

Background:

A strategy to reduce the secondary effects of anti-cancer agents is to potentiate the therapeutic effect by their combination. A combination of vitamin K3 (VK3) and ascorbic acid (AA) exhibited an anti-cancer synergistic effect, associated with extracellular production of H₂O₂ that promoted cell death.

Methods:

The redox-silent vitamin E analogue α-tocopheryl succinate (α-TOS) was used in combination with VK3 and AA to evaluate their effect on prostate cancer cells.

Results:

Prostate cancer cells were sensitive to α-TOS and VK3 treatment, but resistant to AA upto 3.2 mM. When combined, a synergistic effect was found for VK3–AA, whereas α-TOS–VK3 and α-TOS–AA combination showed an antagonist and additive effect, respectively. However, sub-lethal doses of AA–VK3 combination combined with a sub-toxic dose of α-TOS showed to induce efficient cell death that resembles autoschizis. Associated with this cell demise, lipid peroxidation, DNA damage, cytoskeleton alteration, lysosomal–mitochondrial perturbation, and release of cytochrome c without caspase activation were observed. Inhibition of lysosomal proteases did not attenuate cell death induced by the combined agents. Furthermore, cell deaths by apoptosis and autoschizis were detected.

Conclusion:

These finding support the emerging idea that synergistic combinations of some agents can overcome toxicity and other side-effects associated with high doses of single drugs creating the opportunity for therapeutically relevant selectivity.

Dielectrophoretic trapping in microwells for manipulation of single cells and small aggregates of particles

In this work we present a novel concept of active microwells based on cylindrical wells able to vertically trap and control single particles by means of negative dielectrophoresis. The device is fabricated by drilling through holes on a polyimide substrate with copper-gold or aluminum metals, forming three annular electrodes within the well. A channel under the device provides a fluid flow filling the microwell by capillarity. Particles are delivered from the top by a microdispenser and applying sinusoidal signals to the electrodes at frequencies ranging from 100kHz to 1.5MHz and amplitudes between 2V and 7V they are successfully trapped and levitated at the level of the central electrode in the middle of microwells with a diameter of 125mum. By changing signal phases, other configurations are also enabled to load particles in the well or eject them from the bottom. The extension to an array of microwells is presented and design rules are described for routing electrode connections and setting signal parameters. K562 cells cultured with Ara-C 1000nM were successfully trapped and controlled in physiological media. Polystyrene beads were also levitated in water and were used for experimental measurements on minimum amplitudes and phase differences in the signals required to levitate beads, confirming the results obtained by simulation.

Microfluidic channel fabrication in dry film resist for production and prototyping of hybrid chips

Microfluidic networks are patterned in a dry film resist (Ordyl SY300/550) that is sandwiched in between two substrates. The technique enables fabrication of complex biochips with active elements both in the bottom and the top substrate (hybrid chips). The resist can be double bonded at relatively low temperatures without the use of extra adhesives. A postbake transfers the resist into a rigid structure. The resist is qualified in terms of resolution, biocompatibility and fluidic sealing. Fabrication in both a fully equipped cleanroom setting as well as a minimally equipped laboratory is described. The technique is applied for dielectrophoresis-based cell separation systems and a fuel cell reaction chamber with micropillars. The dry film resist can be considered a cheap and fast alternative to SU-8.

Levitation and movement of human tumor cells using a printed circuit board device based on software-controlled dielectrophoresis

In this study we describe an original, efficient, and innovative printed circuit board (PCB) device able to generate dielectrophoresis-based, software-controlled cages that can be moved to any place inside a microchamber. Depending on their dielectrophoretic properties, eukaryotic cells can be "entrapped" in cages and moved under software control. The main conclusion gathered from the experimental data reported is that the PCB device based on dielectrophoresis permits levitation and movement of different tumor cells at different dielectrophoresis conditions. The results presented herein are therefore the basis for experiments aimed at forced interactions or separation of eukaryotic cells using "lab-on-a-chip." In fact, because many cages can be controlled at the same time, and two or more cages can be forced to share the same or a different location, it is possible, in principle, either to bring in contact cells of a differing histotype or to separate them.

Isolated left ventricular filling abnormalities may predict interleukin-2-induced cardiovascular toxicity

Interleukin-2 (IL-2) is a cytokine with proven activity against metastatic renal cell carcinoma (RCC) and malignant melanoma (MM). The intravenous administration of high-dose IL-2 is limited by important cardiovascular side effects such as hypotension, fluid retention, arrhythmias, and myocardial ischemia, which often cause dose reduction and/or treatment withdrawal. The occurrence of these toxic events is not predicted by routine pretreatment examinations. The aim of the present study was to test the reliability of serial echocardiography in predicting subsequent cardiac adverse effects in patients undergoing IL-2 administration. In 19 patients (15 men, 4 women; median age: 51 years, range 27-71 years; 10 affected by metastatic RCC and 9 affected by MM) we performed two-dimensional and Doppler echocardiography before and immediately after 28 continuous intravenous infusions (CIVI) of IL-2 at the dose of 18 MIU/m2/day for 4 days. Left ventricular systolic function and the diastolic transmitral flow pattern were assessed before and after IL-2 administration. Significant changes of two indexes of left ventricular filling were noted: a decrease of the ratio of maximal flow velocity in early diastole to that in late diastole (E/A) (basal: 1.12 +/- 0.46, mean +/- SD; posttreatment: 0.83 +/- 0.27; p < 0.01) and an increase of the percentage of the atrial contribution to left ventricular filling (basal: 37.75 +/- 11.58%; posttreatment: 49.43 +/- 16.48%; p < 0.01). Eight major cardiovascular events causing IL-2 infusion withdrawal were observed (two ischemic electrocardiographic modifications, three grade III-IV hypotension, one atrial fibrillation, one pericardial effusion, one acute heart failure). These major cardiovascular events were observed more often when an abnormal basal E/A ratio < 1.0 (p < 0.05) was found. We conclude that Doppler transmitral flow pattern analysis before and subsequent to IL-2 infusion is a useful and easily available procedure for the monitoring of cardiac modifications during CIVI IL-2 administration. It might also predict a major cardiovascular event during IL-2 administration. Patients with basal E/A ratio < 1.0 should be more carefully monitored during treatment and/or should be treated with lower IL-2 doses to avoid cardiovascular toxicity.

Highly constrained neural networks for industrial quality control

In this work we investigate techniques for embedding domain-specific spatial invariances into highly-constrained neural networks. This information is used to drastically reduce the number of weights which have to be determined during the learning phase, thus allowing us to apply artificial neural networks to problems characterized by a relatively small number of available examples. As an application of the proposed methodology, we study the problem of optical inspection of machined parts. More specifically, we have characterized the performance of a network created according to this strategy, which accepts images of parts under inspection at its input and issues a flag at its output which states whether the part is defective. The results obtained so far show that the proposed methodology provides a potentially relevant approach for the quality control of industrial parts, as it offers both accuracy and short software development time, when compared with a classifier implemented using a standard approach.

Adaptive Voting Rules for k-Nearest Neighbors Classifiers

A simple form of cooperation between the k-nearest neighbors (NN) approach to classification and the neural-like property of adaptation is explored. A tunable, high level k-nearest neighbors decision rule is defined that comprehends most previous generalizations of the common majority rule. A learning procedure is developed that applies to this rule and exploits those statistical features that can be induced from the training set. The overall approach is tested on a problem of handwritten character recognition. Experiments show that adaptivity in the decision rule may improve the recognition and rejection capability of standard k-NN classifiers.

[Sea-blue histiocytosis. I. Cytological study]

Traumatic blindness is a well recognized entity with a guarded prognosis. Previous studies have variously reported the incidence of concomitant optic canal fractures and response to surgical therapy. With the advent of CT scanning, a new technique for study of these severely injured patients has become available. Over a period of 20 months, optic foramen fractures were demonstrated in 10 such patients using finely collimated, high-resolution CT scans. Fractures were easily classified by location, relation to the optic nerve assessed, and associated facial injuries imaged. The technique is easy, rapid, and superior to polytomography in this setting. Possible implications for therapy are discussed.

[Incidence and clinical aspects of Meckel's diverticulum and its complications]

Meckel's diverticulum is usually discovered at laparatomy and the AA. ful that it should be removed regardless of its pathology because of the difficulty in making a diagnosis and the significant mortality rate associated with its complications.