Overcoming the hurdles: surmounting acquired resistance to anti-EGFR therapy in metastatic colorectal cancer.

Colorectal cancer is the third most prevalent cancer type in the United States, with an alarming incidence and mortality rate, especially among individuals younger than 50 years. The epidermal growth factor receptor (EGFR), essential for cell proliferation and survival, has surfaced as a promising therapeutic target for metastatic colorectal cancer and has demonstrated success in various clinical trials. Monoclonal antibodies such as cetuximab and panitumumab have proven to be effective against EGFR by blocking vital downstream signaling pathways and inhibiting gene transcription and cell proliferation. Despite this promise, most patients eventually develop resistance to anti-EGFR treatment, thereby limiting its long-term efficacy. Genomic alterations, such as mutations in KRAS, NRAS, and BRAF, often bypass the EGFR receptor, promoting resistance to therapy. Although our understanding of primary resistance to anti-EGFR therapy has improved, acquired resistance remains a significant hurdle. This review explores the potential mechanisms underpinning this acquired resistance and strategies to overcome it.

The role of total ankle replacement in patients with haemophilia and end-stage ankle arthropathy: A review.

Haemophilia is the most common X-linked bleeding disorder, affecting over 1 million individuals throughout the world. Patients are subclassified into mild, moderate and severe disease based on per cent factor activity level. Nearly, all patients with haemophilia develop haemophilic arthropathy (HA) by age 30 and HA is known to have a negative impact on physical health subscores in Haem-A-QOL, a validated quality of life scoring system for patients with haemophilia. Unfortunately, many patients progress to end-stage HA of the ankle, which is characterized by pain, contractures, decreased range of motion and muscle atrophy. Ankle arthrodesis (AAD) has been the standard of care in the definitive surgical management of end-stage HA of the ankle. While AAD is a safe surgical procedure known to improve HA-related pain, it decreases functional mobility and has been associated with secondary hindfoot arthritis as well as subtalar degeneration. In recent years, total ankle replacement (TAR) has emerged as an alternative surgical procedure that strives to improve functional mobility, pain and quality of life in end-stage HA of the ankle. However, the safety, durability, and efficacy of this procedure in these patients are unknown. In this review, we analyse the clinical studies investigating TAR in patients with end-stage HA of the ankle. We also discuss important considerations in the perioperative management of patients with haemophilia and compare the risks and benefits of AAD and TAR for patients with end-stage HA of the ankle.

Differences in peripheral neuropathy in xeroderma pigmentosum complementation groups A and D as evaluated by nerve conduction studies.

BACKGROUND: Xeroderma pigmentosum (XP) is a rare autosomal recessive genetic disorder with defective DNA nucleotide excision repair and associated with a high frequency of skin cancer. Approximately 25% of patients develop progressive neurological degeneration. Complementation groups XP-A and XP-D are most frequently associated with neurological disorders. DESIGN/METHODS: This is a retrospective review of patients with XP who were evaluated at NIH from 1986 to 2015 and had nerve conduction studies (NCS). In the complementation groups with peripheral neuropathy, further comparisons of the NCS were made with audiological, brain imaging, neuropsychological assessments that were also performed on most of the patients. Limited neuropathology of XP-A and XP-D patients were examined.. RESULTS: The 33 patients had NCS: XP-A (9 patients), XP-C (7 patients), XP-D (10 patients), XP-E (1 patient), XP-V (4 patients), and XP-unknown (2 patients). Peripheral neuropathy based on nerve conduction studies was documented only in two complementation groups: 78% (7/9) of XP-A patients had a sensorimotor neuropathy while 50% (5/10) of XP-D patients had a sensory neuropathy only. Analysis of sural sensory nerve amplitude in both complementation groups XP-A and XP-D correlated with sensorineural hearing loss (SNHL), MRI/CT severity, and Full-scale Intelligence Quotient (IQ). Analysis of fibular motor nerve amplitude in complementation XP-A correlated with SNHL and MRI/CT severity. Limited follow-up studies showed gradual loss of NCS responses compared to an earlier and more rapid progression of the hearing loss. CONCLUSIONS: Despite similar brain imaging and audiological findings patients, XP-A and XP-D complementation groups differ in the type of neuropathy, sensorimotor versus sensory alone. A few cases suggest that sensorineural hearing loss may precede abnormal NCS in XP and therefore serve as valuable clinical indicators of XP patients that will later develop peripheral neuropathy.

Incomplete penetrance for isolated congenital asplenia in humans with mutations in translated and untranslated RPSA exons.

Isolated congenital asplenia (ICA) is the only known human developmental defect exclusively affecting a lymphoid organ. In 2013, we showed that private deleterious mutations in the protein-coding region of RPSA, encoding ribosomal protein SA, caused ICA by haploinsufficiency with complete penetrance. We reported seven heterozygous protein-coding mutations in 8 of the 23 kindreds studied, including 6 of the 8 multiplex kindreds. We have since enrolled 33 new kindreds, 5 of which are multiplex. We describe here 11 new heterozygous ICA-causing RPSA protein-coding mutations, and the first two mutations in the 5'-UTR of this gene, which disrupt mRNA splicing. Overall, 40 of the 73 ICA patients (55%) and 23 of the 56 kindreds (41%) carry mutations located in translated or untranslated exons of RPSA. Eleven of the 43 kindreds affected by sporadic disease (26%) carry RPSA mutations, whereas 12 of the 13 multiplex kindreds (92%) carry RPSA mutations. We also report that 6 of 18 (33%) protein-coding mutations and the two (100%) 5'-UTR mutations display incomplete penetrance. Three mutations were identified in two independent kindreds, due to a hotspot or a founder effect. Finally, RPSA ICA-causing mutations were demonstrated to be de novo in 7 of the 23 probands. Mutations in RPSA exons can affect the translated or untranslated regions and can underlie ICA with complete or incomplete penetrance.

Magnetic Resonance Imaging-Based Screening for Asymptomatic Brain Tumors: A Review.

Brain tumors comprise 2% of all cancers but are disproportionately responsible for cancer-related deaths. The 5-year survival rate of glioblastoma, the most common form of malignant brain tumor, is only 4.7%, and the overall 5-year survival rate for any brain tumor is 34.4%. In light of the generally poor clinical outcomes associated with these malignancies, there has been interest in the concept of brain tumor screening through magnetic resonance imaging. Here, we will provide a general overview of the screening principles and brain tumor epidemiology, then highlight the major studies examining brain tumor prevalence in asymptomatic populations in order to assess the potential benefits and drawbacks of screening for brain tumors. IMPLICATIONS FOR PRACTICE: Magnetic resonance imaging (MRI) screening in healthy asymptomatic adults can detect both early gliomas and other benign central nervous system abnormalities. Further research is needed to determine whether MRI will improve overall morbidity and mortality for the screened populations and make screening a worthwhile endeavor.

Diminution of signal transducer and activator of transcription 3 signaling inhibits vascular permeability and anaphylaxis.

BACKGROUND: During IgE-mediated immediate hypersensitivity reactions, vascular endothelial cells permeabilize in response to mast cell mediators. We have demonstrated previously that patients and mice with signal transducer and activator of transcription 3 (STAT3) mutations (autosomal dominant hyper-IgE syndrome [AD-HIES]) are partially protected from anaphylaxis. OBJECTIVES: We sought to study the mechanism by which STAT3 contributes to anaphylaxis and determine whether small-molecule inhibition of STAT3 can prevent anaphylaxis. METHODS: Using unaffected and STAT3-inhibited or genetic loss-of-function samples, we performed histamine skin prick tests, investigated the contribution of STAT3 to animal models of anaphylaxis, and measured endothelial cell permeability, gene and protein expression, and histamine receptor-mediated signaling. RESULTS: Although mouse mast cell degranulation was minimally affected by STAT3 blockade, mast cell mediator-induced anaphylaxis was blunted in Stat3 mutant mice with AD-HIES and in wild-type mice subjected to small-molecule STAT3 inhibition. Histamine skin prick test responses were diminished in patients with AD-HIES. Human umbilical vein endothelial cells derived from patients with AD-HIES or treated with a STAT3 inhibitor did not signal properly through Src or cause appropriate dissolution of the adherens junctions made up of the proteins vascular endothelial-cadherin and ß-catenin. Furthermore, we found that diminished STAT3 target microRNA17-92 expression in human umbilical vein endothelial cells from patients with AD-HIES is associated with increased phosphatase and tensin homolog (PTEN) expression, which inhibits Src, and increased E2F transcription factor 1 expression, which regulates ß-catenin cellular dynamics. CONCLUSIONS: These data demonstrate that STAT3-dependent transcriptional activity regulates critical components for the architecture and functional dynamics of endothelial junctions, thus permitting vascular permeability.

Transplant Eligible and Ineligible Elderly Patients with AML-A Genomic Approach and Next Generation Questions.

The management of elderly patients diagnosed with acute myelogenous leukemia (AML) is complicated by high relapse risk and comorbidities that often preclude access to allogeneic hematopoietic cellular transplantation (allo-HCT). In recent years, fast-paced FDA drug approval has reshaped the therapeutic landscape, with modest, albeit promising improvement in survival. Still, AML outcomes in elderly patients remain unacceptably unfavorable highlighting the need for better understanding of disease biology and tailored strategies. In this review, we discuss recent modifications suggested by European Leukemia Network 2022 (ELN-2022) risk stratification and review recent aging cell biology advances with the discussion of four AML cases. While an older age, >60 years, does not constitute an absolute contraindication for allo-HCT, the careful patient selection based on a detailed and multidisciplinary risk stratification cannot be overemphasized.

Evolving Standards of Care in the Management of Localized Colorectal Cancer.

The treatment of patients with localized rectal cancer is complex and requires input from a multidisciplinary team. Baseline local staging and mismatch repair protein testing are vital to develop individualized treatment plans. There are multiple options in terms of treatment modalities and sequencing, including transanal excision, short-course radiation, long-course chemoradiation, chemotherapy doublet or triplet, nonoperative management, and immune checkpoint blockade for patients with mismatch repair deficient tumors. While localized colon cancer is typically treated with surgical resection and consideration of adjuvant chemotherapy, emerging data suggest that neoadjuvant chemotherapy may be beneficial in patients with higher-risk disease. Quality-of-life considerations are imperative to prevent potential chronic effects on psychosocial health, neuropathy, fertility, and bowel, bladder, and sexual function. The omission of radiation or surgery can mitigate these toxicities without diminishing oncologic outcomes. The optimal treatment plan and sequence is not a one-size-fits-all approach but rather should be personalized to the patient's disease burden, tumor location, comorbidities, and preferences.

A Multicenter Retrospective Chart Review of Clinical Outcomes Among Patients With KRAS G12C Mutant Non-Small Cell Lung Cancer.

BACKGROUND: On May 28, 2021, the United States Food and Drug Administration (FDA) granted accelerated approval to sotorasib for second-line or later treatment of patients with locally advanced or metastatic KRAS G12C mutant non-small cell lung cancer (NSCLC). This was the first FDA-approved targeted therapy for this patient population. Due to a paucity of real world data describing clinical outcomes in patients with locally advanced or metastatic KRAS G12C mutated NSCLC in the second-line or later, we sought to compile a large, academic medical center-based historical dataset to clarify clinical outcomes in this patient population. MATERIALS AND METHODS: The clinical outcomes of 396 patients with stage IV (n = 268, 68%) or recurrent, metastatic (n = 128, 32%) KRAS G12C mutant NSCLC were evaluated in this multicenter retrospective chart review conducted through the Academic Thoracic Oncology Medical Investigator's Consortium (ATOMIC). Patients treated at 13 sites in the United States and Canada and diagnosed between 2006 and 2020 (30% 2006-2015, 70% 2016-2020) were included. Primary outcomes included real-world PFS (rwPFS) and overall survival (OS) from time of stage IV or metastatic diagnosis, with particular interest in patients treated with second-line docetaxel-containing regimens, as well as clinical outcomes in the known presence or absence of STK11 or KEAP1 comutations. RESULTS: Among all patients with stage IV or recurrent, metastatic KRAS G12C mutant NSCLC (n = 201 with KRAS G12C confirmed prior to first line systemic therapy), the median first-line rwPFS was 9.3 months (95% CI, 7.3-11.8 months) and median OS was 16.8 months (95% CI, 12.7-22.3 months). In this historical dataset, first line systemic therapy among these 201 patients included platinum doublet alone (44%), PD-(L)1 inhibitor monotherapy (30%), platinum doublet chemotherapy plus PD-(L)1 inhibitor (18%), and other regimens (8%). Among patients with documented second-line systemic therapy (n = 123), the second-line median rwPFS was 8.3 months (95% CI, 6.1-11.9 months), with median rwPFS 4.6 months (95% CI, 1.4-NA) among 10 docetaxel-treated patients (9 received docetaxel and 1 received docetaxel plus ramucirumab). Within the total study population, 49 patients (12%) had a co-occurring STK11 mutation and 3 (1%) had a co-occurring KEAP1 mutation. Among the 49 patients with a co-occurring KRAS G12C and STK11 mutation, median rwPFS on first-line systemic therapy (n = 23) was 6.0 months (95% CI, 4.7-NA), and median OS was 14.0 months (95% CI, 10.8-35.3 months). CONCLUSION: In this large, multicenter retrospective chart review of patients with KRAS G12C mutant NSCLC we observed a relatively short median rwPFS of 4.6 months among 10 patients with KRAS G12C mutant NSCLC treated with docetaxel with or without ramucirumab in the second-line setting, which aligns with the recently reported CodeBreak 200 dataset.

Race & sex disparities related to low-dose computed tomography lung cancer screening eligibility criteria: A lung cancer cases review.

INTRODUCTION: The United States Preventive Services Task Force (USPSTF) recommendations do not account for race and sex differences in lung cancer risk. We compared the sensitivity for finding lung cancer cases eligible for lung cancer screening (LCS) by USPSTF 2013 recommendations versus the PLCOm2012 model at an equivalent threshold. METHODS: Using Georgetown University Hospital tumor registry, we identified lung cancer cases (≥55 years old) between 2014 and 2018. Medical chart review collected age, sex, race, education, smoking, and clinical characteristics. We compared the percentage meeting eligibility criteria overall, and by race and sex. RESULTS: The cases (N = 447) were 36.6% Black and 52.6% female. The PLCOm2012 and USPSTF 2013 criteria identified 71.4% and 45.6% of cases, respectively (p < 0.0001). This difference was consistent across race and sex sub-groups (p < 0.0001). The PLCOm2012 was more sensitive than the USPSTF in Blacks (69.9% vs. 46.6%, p < 0.0001) and in women (69.8% vs. 41.3%, p < 0.0001). The USPSTF had poor sensitivity for both race groups (Black 46.6%, White 45.9%, p = 0.886) and had lower sensitivity in women vs. men (41.3% vs. 51.4%, p = 0.032). The PLCOm2012 had higher sensitivities in women and men, and difference between sexes was not significant (69.8% vs. 72.6%, p = 0.506). CONCLUSIONS: Compared to the USPSTF 2013 recommendations, the PLCOm2012 model selected a larger proportion of lung cancer cases in all race-sex strata and removed the sex disparity observed for the USPSTF. The PLCOm2012 risk model could be used to identify those who will benefit from LCS.

Comprehensive Analysis of R-Spondin Fusions and RNF43 Mutations Implicate Novel Therapeutic Options in Colorectal Cancer.

PURPOSE: Gene fusions involving R-spondin (RSPOfp) and RNF43 mutations have been shown to drive Wnt-dependent tumor initiation in colorectal cancer. Herein, we aimed to characterize the molecular features of RSPOfp/RNF43 mutated (mut) compared with wild-type (WT) colorectal cancers to gain insights into potential rationales for therapeutic strategies. EXPERIMENTAL DESIGN: A discovery cohort was classified for RSPOfp/RNF43 status using DNA/RNA sequencing and IHC. An independent cohort was used to validate our findings. RESULTS: The discovery cohort consisted of 7,245 colorectal cancer samples. RSPOfp and RNF43 mutations were detected in 1.3% (n = 94) and 6.1% (n = 443) of cases. We found 5 RSPO fusion events that had not previously been reported (e.g., IFNGR1-RSPO3). RNF43-mut tumors were associated with right-sided primary tumors. No RSPOfp tumors had RNF43 mutations. In comparison with WT colorectal cancers, RSPOfp tumors were characterized by a higher frequency of BRAF, BMPR1A, and SMAD4 mutations. APC mutations were observed in only a minority of RSPOfp-positive compared with WT cases (4.4% vs. 81.4%). Regarding RNF43 mutations, a higher rate of KMT2D and BRAF mutations were detectable compared with WT samples. Although RNF43 mutations were associated with a microsatellite instability (MSI-H)/mismatch repair deficiency (dMMR) phenotype (64.3%), and a tumor mutation burden ≥10 mt/Mb (65.8%), RSPOfp was not associated with MSI-H/dMMR. The validation cohort replicated our genetic findings. CONCLUSIONS: This is the largest series of RSPOfp/RNF43-mut colorectal cancers reported to date. Comprehensive molecular analyses asserted the unique molecular landscape associated with RSPO/RNF43 and suggested potential alternative strategies to overcome the low clinical impact of Wnt-targeted agents and immunotherapy.

Pembrolizumab-induced cytokine release syndrome in a patient with metastatic lung adenocarcinoma: a case report.

Cytokine release syndrome (CRS) is a well-described immune-related adverse event following chimeric antigen receptor T-cell therapy, but has rarely been reported following anti-programmed death ligand-1 therapy. We report the case of a 55-year-old man with metastatic lung adenocarcinoma who presented with fever, chills and hypotension. Initial labs were notable for highly elevated serum ferritin levels and mildly elevated triglyceride levels. He was ultimately diagnosed with pembrolizumab-induced CRS complicated by multiorgan failure. The patient was treated with steroids and tocilizumab with normalization of inflammatory markers and resolution of renal failure. This case not only highlights the importance of considering CRS in patients who have developed multiorgan failure after immune checkpoint inhibitor therapy, but also demonstrates clinical similarities between CRS and other hyperinflammatory states such as hemophagocytic lymphohistiocytosis.

A Prospective Cohort Study of Factors Associated With Place of Death Among Patients With Late-Stage Cancer in Southern Africa.

CONTEXT: Identifying factors that affect terminally ill patients' preferences for and actual place of death may assist patients to die wherever they wish. OBJECTIVE: The objective of this study was to investigate factors associated with preferred and actual place of death for cancer patients in Johannesburg, South Africa. METHODS: In a prospective cohort study at a tertiary hospital in Johannesburg, South Africa, adult patients with advanced cancer and their caregivers were enrolled from 2016 to 2018. Study nurses interviewed the patients at enrollment and conducted postmortem interviews with the caregivers. RESULTS: Of 324 patients enrolled, 191 died during follow-up. Preferred place of death was home for 127 (66.4%) and a facility for 64 (33.5%) patients; 91 (47.6%) patients died in their preferred setting, with a kappa value of congruence of 0.016 (95% CI = -0.107, 0.139). Factors associated with congruence were increasing age (odds ratio [OR]: 1.03, 95% CI: 1.00-1.05), use of morphine (OR: 1.87, 95% CI: 1.04-3.36), and wanting to die at home (OR: 0.44, 95% CI: 0.24-0.82). Dying at home was associated with increasing age (OR 1.03, 95% CI 1.00-1.05) and with the patient wishing to have family and/or friends present at death (OR 6.73, 95% CI 2.97-15.30). CONCLUSION: Most patients preferred to die at home, but most died in hospital and fewer than half died in their preferred setting. Further research on modifiable factors, such as effective communication, access to palliative care and morphine, may ensure that more cancer patients in South Africa die wherever they wish.

Epidemiologic trends in neuroendocrine tumors: An examination of incidence rates and survival of specific patient subgroups over the past 20 years.

INTRODUCTION: Neuroendocrine tumors (NETs) represent a small proportion of cancers, but are increasing in incidence due to incidental diagnosis. We examined NET incidence and survival over time in a population-based registry. MATERIALS/METHODS: We identified all NET cases diagnosed between 1995 and 2014 in the Surveillance, Epidemiology, and End Results database, November 2016 submission. We determined incidence rates and calculated overall and cancer-specific survival curves in different subgroups stratified by grade, stage, and age at diagnosis. RESULTS: We identified 85,133 patients with a diagnosis of NET between 1995 and 2014. Patients with grade 1, localized NETs had the best median overall survival (233 months, 95% confidence intervals [CI] not estimable) and 5-year cancer-specific survival (97.6%; 95% CI, 97.4%, 97.8%). The median overall survival decreased with age across the entire spectrum of ages, with patients >70 years having a particularly poor prognosis (28.0 months; 95% CI, 26.5, 29.5). Patients >70 years old often had distant (34.3%) or grade 3 disease (40.8%), but even elderly patients with lower grade and/or stage disease had worse median overall survival compared with younger subjects. CONCLUSIONS: Age appears to be associated with a worse prognosis independent of NET stage, and grade at the time of diagnosis. Patients with grade 1, localized NETs have an excellent long-term prognosis. Further research is warranted on reducing intensity of surveillance in these patients.

Informal Caregiver Challenges for Advanced Cancer Patients During End-of-Life Care in Johannesburg, South Africa and Distinctions Based on Place of Death.

CONTEXT: In sub-Saharan Africa, late diagnosis with cancer is common. Many dying patients rely on family members for care; little is known about the challenges African informal caregivers face. OBJECTIVES: To better understand the challenges of informal caregivers at the end of life in South Africa, both at home and in inpatient facilities. METHODS: We included advanced cancer patients and caregivers from a public hospital in Johannesburg, South Africa. Study nurses interviewed patients and caregivers about their experiences. Using univariate and multivariate analyses, we determined the factors associated with greater caregiver difficulty, focusing on patients dying at home vs. in inpatient facilities. RESULTS: Among 174 informal caregivers, 62 (36%) reported "a lot" of challenges. These caregivers struggled most with keeping the patient clean (16%) and with patient interactions (34%). Symptoms associated with greater difficulty included pain (odds ratio [OR] 2.4 [95% CI 1.2-4.7]), urinary incontinence (OR 2.3 [95% CI 1.1-4.9]), fecal incontinence (OR 2.4 [95% CI 1.0-5.7]), insomnia (OR 2.9 [95% CI 1.3-6.9]), fatigue (OR 6.3 [95% CI 1.8-21.6]), extremity weakness (OR 2.9 [95% CI 1.3-6.9]), shame (OR 4.2 [95% CI 1.5-12.0]), and sadness (OR 2.3 [95% CI 1.1-4.8]). Caregivers of patients dying at home reported the greatest difficulty with patients' physical symptoms; caregivers of those dying in facilities reported the greatest difficulty with emotional symptoms. CONCLUSION: Informal caregivers of patients dying at home reported challenges with practical functional care; this effect was reduced in the inpatient setting. Skills training for these caregivers could relieve some of this burden.

FOXP3+ Tregs require WASP to restrain Th2-mediated food allergy.

In addition to the infectious consequences of immunodeficiency, patients with Wiskott-Aldrich syndrome (WAS) often suffer from poorly understood exaggerated immune responses that result in autoimmunity and elevated levels of serum IgE. Here, we have shown that WAS patients and mice deficient in WAS protein (WASP) frequently develop IgE-mediated reactions to common food allergens. WASP-deficient animals displayed an adjuvant-free IgE-sensitization to chow antigens that was most pronounced for wheat and soy and occurred under specific pathogen-free as well as germ-free housing conditions. Conditional deletion of Was in FOXP3+ Tregs resulted in more severe Th2-type intestinal inflammation than that observed in mice with global WASP deficiency, indicating that allergic responses to food allergens are dependent upon loss of WASP expression in this immune compartment. While WASP-deficient Tregs efficiently contained Th1- and Th17-type effector differentiation in vivo, they failed to restrain Th2 effector responses that drive allergic intestinal inflammation. Loss of WASP was phenotypically associated with increased GATA3 expression in effector memory FOXP3+ Tregs, but not in naive-like FOXP3+ Tregs, an effect that occurred independently of increased IL-4 signaling. Our results reveal a Treg-specific role for WASP that is required for prevention of Th2 effector cell differentiation and allergic sensitization to dietary antigens.

Ribosomal protein SA haploinsufficiency in humans with isolated congenital asplenia.

Isolated congenital asplenia (ICA) is characterized by the absence of a spleen at birth in individuals with no other developmental defects. The patients are prone to life-threatening bacterial infections. The unbiased analysis of exomes revealed heterozygous mutations in RPSA in 18 patients from eight kindreds, corresponding to more than half the patients and over one-third of the kindreds studied. The clinical penetrance in these kindreds is complete. Expression studies indicated that the mutations carried by the patients-a nonsense mutation, a frameshift duplication, and five different missense mutations-cause autosomal dominant ICA by haploinsufficiency. RPSA encodes ribosomal protein SA, a component of the small subunit of the ribosome. This discovery establishes an essential role for RPSA in human spleen development.