Trastuzumab deruxtecan in patients with metastatic non-small-cell lung cancer (DESTINY-Lung01): primary results of the HER2-overexpressing cohorts from a single-arm, phase 2 trial

BACKGROUND

DESTINY-Lung01 is a multicentre, open-label, phase 2 study evaluating the antitumour activity and safety of trastuzumab deruxtecan, a HER2-directed antibody-drug conjugate, in patients with HER2-overexpressing or HER2 (ERBB2)-mutant unresectable or metastatic non-small-cell lung cancer (NSCLC). The results of the HER2-mutant cohort (cohort 2) have been reported elsewhere. Herein, we report the primary analysis of cohorts 1 and 1A, which aimed to evaluate the activity and safety of trastuzumab deruxtecan 5·4 mg/kg and 6·4 mg/kg in patients with HER2-overexpressing NSCLC.

METHODS

Patients aged 18 years or older with unresectable or metastatic (or both unresectable and metastatic) non-squamous NSCLC who had relapsed following or were refractory to standard treatment or for whom no standard treatment was available, with an HER2 immunohistochemistry score of 3+ or 2+ (without known HER2 mutations) and an Eastern Cooperative Oncology Group performance status score of 0 or 1, were enrolled at 20 specialist hospitals in France, Japan, the Netherlands, Spain, and the USA. Patients were assigned to cohorts sequentially, first to cohort 1, to receive trastuzumab deruxtecan 6·4 mg/kg (cohort 1), then to cohort 1A, to receive trastuzumab deruxtecan 5·4 mg/kg, both administered intravenously once every 3 weeks. The primary endpoint was confirmed objective response rate by independent central review and was assessed in the full analysis set, which included all patients who signed an informed consent form and were enrolled in the study. Safety was assessed in all enrolled patients who received at least one dose of trastuzumab deruxtecan. This trial is registered with ClinicalTrials.gov, NCT03505710, and is ongoing (closed to recruitment).

FINDINGS

Between Aug 27, 2018, and Jan 28, 2020, 49 patients were enrolled in cohort 1 (median age 63·0 years [IQR 58·0-68·0], 30 [61%] male, 19 [39%] female, and 31 [63%] White), and from June 16 to Dec 9, 2020, 41 patients were enrolled in cohort 1A (median age 62·0 years [IQR 56·0-66·0], 22 [54%] male, 19 [46%] female, and 31 [76%] White). As of data cutoff (Dec 3, 2021), the median treatment duration was 4·1 months (IQR 1·4-7·1) in cohort 1 and 5·5 months (1·4-8·7) in cohort 1A, and median follow-up was 12·0 months (5·4-22·4) in cohort 1 and 10·6 months (4·5-13·5) in cohort 1A. Confirmed objective response rate by independent central review was 26·5% (95% CI 15·0-41·1; 13 of 49, all partial responses) in cohort 1 and 34·1% (20·1-50·6; 14 of 41; two complete responses and 12 partial responses) in cohort 1A. The most common treatment-emergent adverse events of grade 3 or worse were neutropenia (12 [24%] of 49 in cohort 1, none in cohort 1A), pneumonia (six [12%] and two [5%], respectively), fatigue (six [12%] and three [7%], respectively), and disease progression (six [12%] and four [10%], respectively). Drug-related treatment-emergent adverse events of grade 3 or worse occurred in 26 (53%) of 41 patients in cohort 1 and nine (22%) of 49 patients in cohort 1A. Drug-related serious adverse events were reported in ten (20%) patients and three (7%) patients, respectively. Deaths due to treatment-emergent adverse events occurred in ten (20%) patients in cohort 1 (disease progression in six (12%) patients and bronchospasm, hydrocephalus, respiratory failure, and pneumonitis in one [2%] patient each), and in seven (17%) patients in cohort 1A (due to disease progression in four (10%) patients and dyspnoea, malignant neoplasm, and sepsis in one (2%) patient each). One death due to a treatment-emergent adverse event was determined to be due to study treatment by the investigator, which was in cohort 1 (pneumonitis). Independent adjudication of interstitial lung disease or pneumonitis found that drug-related interstitial lung disease or pneumonitis occurred in ten (20%) patients in cohort 1 (two [4%] grade 1, five [10%] grade 2, and three [6%] grade 5) and two (5%) patients in cohort 1A (one [2%] grade 2 and one [2%] grade 5). An additional patient in cohort 1A had grade 4 pneumonitis after the data cutoff, which was subsequently adjudicated as drug-related grade 5 interstitial lung disease or pneumonitis.

INTERPRETATION

Given the low antitumour activity of existing treatment options in this patient population, trastuzumab deruxtecan might have the potential to fill a large unmet need in HER2-overexpressing NSCLC. Our findings support further investigation of trastuzumab deruxtecan in patients with HER2-overexpressing NSCLC.

FUNDING

Daiichi Sankyo and AstraZeneca.

Intracranial Efficacy of Adagrasib in Patients From the KRYSTAL-1 Trial With KRASG12C-Mutated Non-Small-Cell Lung Cancer Who Have Untreated CNS Metastases

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.Patients with Kirsten rat sarcoma viral oncogene homolog (KRAS)-mutated non-small-cell lung cancer (NSCLC) and untreated CNS metastases have a worse prognosis than similar patients without KRAS mutations. Adagrasib has previously demonstrated CNS penetration preclinically and cerebral spinal fluid penetration clinically. We evaluated adagrasib in patients with KRASG12C-mutated NSCLC and untreated CNS metastases from the KRYSTAL-1 trial (ClinicalTrials.gov identifier: NCT03785249; phase Ib cohort), in which adagrasib 600 mg was administered orally, twice daily. Study outcomes included the safety and clinical activity (intracranial [IC] and systemic) by blinded independent central review. Twenty-five patients with KRASG12C-mutated NSCLC and untreated CNS metastases were enrolled and evaluated (median follow-up, 13.7 months); 19 patients were radiographically evaluable for IC activity. Safety was consistent with previous reports of adagrasib, with grade 3 treatment-related adverse events (TRAEs) in 10 patients (40%) and one grade 4 (4%) and no grade 5 TRAEs. The most common CNS-specific TRAEs included dysgeusia (24%) and dizziness (20%). Adagrasib demonstrated an IC objective response rate of 42%, disease control rate of 90%, progression-free survival of 5.4 months, and median overall survival of 11.4 months. Adagrasib is the first KRASG12C inhibitor to prospectively demonstrate IC activity in patients with KRASG12C-mutated NSCLC and untreated CNS metastases, supporting further investigation in this population.

CNS Downstaging: An Emerging Treatment Paradigm for Extensive Brain Metastases in Oncogene-Addicted Lung Cancer

INTRODUCTION

For extensive brain metastases (BrM) presentations arising from oncogene-addicted lung cancer, tyrosine kinase inhibitors (TKIs) with high response rates in the central nervous system (CNS) could potentially downstage the CNS disease burden, allowing for the avoidance of upfront whole-brain radiotherapy (WBRT) and the conversion of some patients into candidates for focal stereotactic radiosurgery (SRS).

METHODS

We describe the outcomes of patients with ALK, EGFR, and ROS1-driven NSCLC with extensive BrM presentations (defined as > 10 BrMs or leptomeningeal disease) treated with upfront newer generation CNS-active TKIs alone, including osimertinib, alectinib, brigatinib, lorlatinib, and entrectinib, from 2012 to 2021 at our institution. All BrMs were contoured at study entry, best CNS response (nadir), and first CNS progression.

RESULTS

Twelve patients met criteria including 6 with ALK, 3 with EGFR, and 3 with ROS1-driven NSCLC. The median number and volume of BrMs at presentation were 49 and 19.6 cm3, respectively. Eleven patients (91.7 %) achieved a CNS response by modified-RECIST criteria to upfront TKI (10 partial responses, 1 complete response, 1 stable disease) with nadir observed at a median of 5.1 months. At nadir, the median number and volume of BrMs were 5 (median 91.7 % reduction per-patient) and 0.3 cm3(median 96.5 % reduction per-patient), respectively. Eleven patients (91.6 %) developed subsequent CNS progression (7 local failures, 3 local + distant, 1 distant) at a median of 17.9 months. At CNS progression, the median number and volume of BrMs were 7 and 0.7 cm3, respectively. Seven patients (58.3 %) received salvage SRS and no patients received salvage WBRT. The median overall survival from initiation of TKI for the extensive BrM presentation was 43.2 months.

CONCLUSION

In this initial case series, we describe CNS downstaging as a promising multidisciplinary treatment paradigm involving the upfront administration CNS-active systemic therapy and close MRI surveillance for extensive BrMs as a strategy to avoid upfront WBRT and to convert some patients into SRS candidates.

Adagrasib in Non-Small-Cell Lung Cancer Harboring a KRASG12C Mutation

BACKGROUND

Adagrasib, a KRAS^G12C inhibitor, irreversibly and selectively binds KRAS^G12C, locking it in its inactive state. Adagrasib showed clinical activity and had an acceptable adverse-event profile in the phase 1-1b part of the KRYSTAL-1 phase 1-2 study.

METHODS

In a registrational phase 2 cohort, we evaluated adagrasib (600 mg orally twice daily) in patients with KRAS^G12C -mutated non-small-cell lung cancer (NSCLC) previously treated with platinum-based chemotherapy and anti-programmed death 1 or programmed death ligand 1 therapy. The primary end point was objective response assessed by blinded independent central review. Secondary end points included the duration of response, progression-free survival, overall survival, and safety.

RESULTS

As of October 15, 2021, a total of 116 patients with KRAS^G12C -mutated NSCLC had been treated (median follow-up, 12.9 months); 98.3% had previously received both chemotherapy and immunotherapy. Of 112 patients with measurable disease at baseline, 48 (42.9%) had a confirmed objective response. The median duration of response was 8.5 months (95% confidence interval [CI], 6.2 to 13.8), and the median progression-free survival was 6.5 months (95% CI, 4.7 to 8.4). As of January 15, 2022 (median follow-up, 15.6 months), the median overall survival was 12.6 months (95% CI, 9.2 to 19.2). Among 33 patients with previously treated, stable central nervous system metastases, the intracranial confirmed objective response rate was 33.3% (95% CI, 18.0 to 51.8). Treatment-related adverse events occurred in 97.4% of the patients - grade 1 or 2 in 52.6% and grade 3 or higher in 44.8% (including two grade 5 events) - and resulted in drug discontinuation in 6.9% of patients.

CONCLUSIONS

In patients with previously treated KRAS^G12C -mutated NSCLC, adagrasib showed clinical efficacy without new safety signals. (Funded by Mirati Therapeutics; ClinicalTrials.gov number, NCT03785249.).

Activity of adagrasib (MRTX849) in patients with KRASG12C-mutated NSCLC and active, untreated CNS metastases in the KRYSTAL-1 trial

LBA9009

Background: CNS metastases (mets) occur in 27–42% of NSCLC harboring KRASG12C mutations and are associated with poor prognosis. Adagrasib (ada), an investigational agent, is a KRASG12C inhibitor that irreversibly and selectively binds KRASG12C, locking it in its inactive state, and is optimized for favorable PK properties, including a long half-life (̃24 h) and dose-dependent PK. Ada has demonstrated dose-dependent CNS penetration and intracranial (IC) tumor regression in preclinical models of CNS mets. Methods: KRYSTAL-1 (NCT03785249) is a multicohort Phase 1/2 study evaluating ada as monotherapy or in combination with selected agents in patients (pts) with advanced solid tumors harboring a KRASG12C mutation. In a Phase 1b cohort, pts with KRASG12C-mutant NSCLC and active, untreated CNS mets were treated with ada 600 mg BID. The objectives for this Phase 1b cohort were to evaluate safety and clinical activity, including systemic and IC objective response rate (ORR) by blinded independent central review (BICR), duration of response (DOR), progression-free survival (PFS), and overall survival (OS). Systemic responses were assessed by RECIST 1.1; IC responses were assessed by modified RANO criteria and IC RECIST. Cerebrospinal fluid (CSF) was collected when feasible and was used to measure ada concentrations for optional evaluation. Results: As of 31 December 2021, 25 pts with NSCLC were enrolled and treated. Median follow-up was 6.6 months at the cutoff date. Median age was 66 years, 52% were female, 28%/72% had ECOG PS 0/1, and median lines of prior systemic therapy was one (range 0–4+). IC ORR per modified RANO criteria by BICR was 31.6% (6/19; 3 CRs, 2 PRs, 1 unconfirmed PR); IC disease control rate (DCR) was 84.2% (16/19, including 10 SDs). Median IC DOR was not reached (95% CI 4.1–NE); median IC PFS was 4.2 months (95% CI 3.8–NE). CSF samples were obtained for two pts for whom regression of CNS mets was observed and ada CSF concentrations exceeded the CNS penetrance partition coefficients observed for other therapies with demonstrated CNS penetration and CNS antitumor activity (Kp,uu 0.47). Systemic ORR by BICR was 35.0% (7/20), DCR was 80.0% (16/20) and median DOR was 9.6 months (95% CI 2.7–9.6); median PFS was 5.6 months (95% CI 3.8–11.0). For all pts enrolled, OS was immature, and the median had not been reached at the time of analysis. Safety was consistent with that previously reported with ada; any grade TRAEs occurred in 96% of pts, grade 3 TRAEs in 36%, and there were no grade 4/5 TRAEs. Further data describing IC activity assessed by IC RECIST will be presented. Conclusions: Ada was well tolerated, and these preliminary data demonstrate CNS penetration and encouraging IC activity in pretreated pts with NSCLC harboring a KRASG12C mutation and active, untreated CNS mets. These are the first clinical data demonstrating CNS-specific activity of a KRASG12C inhibitor in this population. Clinical trial information: NCT03785249.

Non-Small Cell Lung Cancer, Version 3.2022, NCCN Clinical Practice Guidelines in Oncology

NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for Non-Small Cell Lung Cancer (NSCLC) provide recommended management for patients with NSCLC, including diagnosis, primary treatment, surveillance for relapse, and subsequent treatment. Patients with metastatic lung cancer who are eligible for targeted therapies or immunotherapies are now surviving longer. This selection from the NCCN Guidelines for NSCLC focuses on targeted therapies for patients with metastatic NSCLC and actionable mutations.

Trastuzumab Deruxtecan in HER2-Mutant Non-Small-Cell Lung Cancer

BACKGROUND

Human epidermal growth factor receptor 2 (HER2)-targeted therapies have not been approved for patients with non-small-cell lung cancer (NSCLC). The efficacy and safety of trastuzumab deruxtecan (formerly DS-8201), a HER2 antibody-drug conjugate, in patients with HER2-mutant NSCLC have not been investigated extensively.

METHODS

We conducted a multicenter, international, phase 2 study in which trastuzumab deruxtecan (6.4 mg per kilogram of body weight) was administered to patients who had metastatic HER2-mutant NSCLC that was refractory to standard treatment. The primary outcome was objective response as assessed by independent central review. Secondary outcomes included the duration of response, progression-free survival, overall survival, and safety. Biomarkers of HER2 alterations were assessed.

RESULTS

A total of 91 patients were enrolled. The median duration of follow-up was 13.1 months (range, 0.7 to 29.1). Centrally confirmed objective response occurred in 55% of the patients (95% confidence interval [CI], 44 to 65). The median duration of response was 9.3 months (95% CI, 5.7 to 14.7). Median progression-free survival was 8.2 months (95% CI, 6.0 to 11.9), and median overall survival was 17.8 months (95% CI, 13.8 to 22.1). The safety profile was generally consistent with those from previous studies; grade 3 or higher drug-related adverse events occurred in 46% of patients, the most common event being neutropenia (in 19%). Adjudicated drug-related interstitial lung disease occurred in 26% of patients and resulted in death in 2 patients. Responses were observed across different HER2 mutation subtypes, as well as in patients with no detectable HER2 expression or HER2 amplification.

CONCLUSIONS

Trastuzumab deruxtecan showed durable anticancer activity in patients with previously treated HER2-mutant NSCLC. The safety profile included interstitial lung disease that was fatal in two cases. Observed toxic effects were generally consistent with those in previously reported studies. (Funded by Daiichi Sankyo and AstraZeneca; DESTINY-Lung01 ClinicalTrials.gov number, NCT03505710.).

Abstract LB054: Confirmation of target inhibition and anti-tumor activity of the SHP2 inhibitor RMC-4630 via longitudinal analysis of ctDNA in a phase 1 clinical study

RMC-4630 is a potent, selective, orally bioavailable allosteric inhibitor of SHP2, a central node in the RAS signaling pathway. Preclinical data have demonstrated that RMC-4630 can shrink tumors carrying certain mutations in the RAS pathway such as KRASG12C, NF1LOF, and BRAFClass3. Longitudinal circulating tumor DNA (ctDNA) was isolated from blood using GuardantOMNI in 80 patients with relapsed/refractory solid tumors in the phase 1 dose-escalation trial of RMC-4630 (NCT03634982) to characterize and confirm RAS pathway mutations and to evaluate molecular responses in patients receiving RMC-4630 monotherapy. Safety, PK and efficacy findings from this study are reported in a separate abstract. 78 of 80 patients had baseline somatic mutations detected in plasma, of which 60 were either KRASG12X, NF1LOF, or BRAFClass3; 48 of these 60 patients also had on-treatment ctDNA assessments and these patients constitute the population reported here. 9 of 48 patients (19%) had KRASG12C detected at baseline, available scan results and a ctDNA sample after 4 weeks of receiving RMC-4630. A decrease in KRASG12C variant allele frequency (VAF) was detected in 5/9 patients (56%) with clearance in 1 patient with a partial response. Decrease in KRASG12C VAF was associated with change in tumor volume (PCC=0.85, p=0.008), preceding scan results by approximately 1 month, suggesting that change in KRASG12C VAF may be an early measure of drug activity or possibly response. 5 of 48 patients (10%) had NF1LOF detected at baseline. A decrease, or stability in NF1LOF VAF on treatment compared to baseline was detected in 4 (80% of all NF1LOF patients). The decrease in NF1LOF VAF was not associated with change in tumor volume and may represent effects of RMC-4630 on a subclone harboring NF1LOF. One patient had a detectable BRAFClass3 mutation at baseline, which decreased in VAF on treatment compared to baseline. Of the remaining patients there were 12 KRASG12D, 9 KRASG12V and other KRASG12X. The majority progressed with an increase in VAF of all mutations including KRASG12X, suggesting that the KRASG12X-containing clone is responsible for escape from single agent RMC-4630. In most instances the increase in KRASG12X VAF in blood preceded determination of clinical progression. Longitudinal assessment of ctDNA indicates that some patients with RAS-addicted tumors undergo a molecular response on treatment with the SHP2 inhibitor RMC-4630.

Citation Format: Josie L. Hayes, Marianna Koczywas, Sai-Hong Ignatius Ou, Pasi A. Janne, Jose M. Pacheco, Susanna Ulahannan, Judy S. Wang, Howard A. Burris, Jonathan W. Riess, Caroline McCoach, Michael S. Gordon, Anna Capasso, Ariel Chen, Richa Dua, Bojena Bitman, Martha Guerra, Hongfang Wang, Xiaolin Wang, Eric Haura. Confirmation of target inhibition and anti-tumor activity of the SHP2 inhibitor RMC-4630 via longitudinal analysis of ctDNA in a phase 1 clinical study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB054.

Mobocertinib: A Potential Treatment for NSCLC with EGFR Exon 20 Insertions

Amivantamab is the only FDA-approved therapy for non-small cell lung cancer (NSCLC) with EGFR exon 20 insertions. Unfortunately, patients eventually develop progression of disease on this therapy, and most do not respond to this treatment. In this issue of Cancer Discovery, Gonzalvez and colleagues and Riely and colleagues highlight preclinical and early clinical data supporting mobocertinib as a potentially efficacious agent for NSCLC with EGFR exon 20 insertions.See related article by Riely et al., p. 1688.See related article by Gonzalvez et al., p. 1672.

Mutational Profile Evaluates Response and Survival to First-Line Chemotherapy in Lung Cancer

Evaluating the therapeutic response and survival of lung cancer patients receiving first-line chemotherapy has always been difficult. Limited biomarkers for evaluation exist and as a result histology represents an empiric tool to guide therapeutic decision making. In this study, molecular signatures associated with response and long-term survival of lung cancer patients receiving first-line chemotherapy are discovered. Whole-exome sequencing is performed on pretherapeutic tissue samples of 186 patients [145 non-small cell lung cancer (NSCLC) and 41 small cell lung cancer (SCLC)]. On the basis of genomic alteration characteristics, NSCLC patients can be classified into four subtypes (C1-C4). The long-term survival is similar among different subtypes. SCLC patients are also divided into four subtypes and significant difference in their progression free survival is revealed (P < 0.001). NSCLC patients can be divided into three subtypes (S1-S3) based on TMB. A trend of worse survival associated with higher TMB in subtype S3 than in S1+S2 is found. In contrast, no significant correlations between molecular subtype and therapeutic response are observed. In conclusion, this study identifies several molecular signatures associated with response and survival to first-line chemotherapy in lung cancer.

Immune-related adverse event profile of combination treatment of PD-(L)1 checkpoint inhibitors and bevacizumab in non-small cell lung cancer patients: data from the FDA adverse event reporting system

Background

Immune checkpoint inhibitors (ICIs) and bevacizumab-based therapy are a promising treatment approach to significantly improving overall survival (OS) of non-small cell lung cancer (NSCLC) patients. However, the incidence of adverse events induced by a combination treatment with programmed cell death-1 or programmed death ligand 1 [PD-(L)1] inhibitor and bevacizumab remains unknown. The current evidence from prospective studies is limited. Thus, efforts using real-world data to further improve our understanding of the potential adverse events will be necessary.

Methods

The present study included 15,872 participants with NSCLC in the FDA Adverse Event Reporting System (FAERS) database from April 2013 to September 2019. The definition of adverse events (AEs) relied on the Medical Dictionary for Regulatory Activities (MedDRA). Statistical analysis was performed, and odds ratio (ORs) with 95% confidence intervals (CIs) were calculated.

Results

Of the 15,872 participants with NSCLC, 15,463 cases were treated with the PD-(L)1 inhibitor monotherapy, while 409 cases were treated with both PD-(L)1 inhibitor and bevacizumab. Compared with monotherapy, combination therapy had lower risks of pneumonitis, respiratory failure, edema, disease progression, and death; however, combination therapy was also associated with significantly higher risks of pyrexia, general physical health deterioration, stomatitis, dehydration, thrombocytopenia, peripheral neuropathy, nephritis, bone marrow failure, immune thrombocytopenic purpura, neutropenia, and serious AEs. The results of the multivariate analysis suggested that combination therapy was the independent risk factor for pyrexia, neutropenia, nephritis, ITP, and the independent protective factor for respiratory failure.

Conclusions

We observed that the spectrum and risk of irAEs differed widely between therapeutic regimens, and irAEs involved multiple organ systems both in monotherapy or combination therapy. Deepening our understanding of irAEs has a great clinical value for improving individualized clinical patient management and the safety of medication use.

Systemic therapy options following first-line chemoimmunotherapy in small-cell lung cancer

Nearly all patients with extensive-stage small-cell lung cancer (ES-SCLC) relapse following first-line etoposide plus platinum (EP) with or without immune checkpoint inhibition. Topotecan and amrubicin are chemotherapies approved for these patients. The toxicities of these chemotherapies are significant and survival when treated with these regimens is minimal. The programmed death-1 (PD-1) inhibitors nivolumab and pembrolizumab are unlikely to be effective for patients who develop progressive disease on first-line chemoimmunotherapy. Newer systemic therapies (e.g., lurbinectedin and temozolomide plus poly-ADP ribose polymerase inhibition) have demonstrated greater response rates than topotecan, amrubicin or PD-1 inhibitors. The data on these newer systemic therapies and other agents that may soon enter clinic are reviewed in this manuscript. Additionally, some of the key questions arising following clinical trials of these newer agents are highlighted.

Immunotherapy for extensive stage small cell lung cancer

Small cell lung cancer (SCLC) is an aggressive malignancy. Until recently the standard of care for newly diagnosed patients with extensive-stage disease was chemotherapy consisting of etoposide plus a platinum (EP). The median overall survival (OS) was only about 10 months with this systemic therapy. Immune checkpoint inhibitors were first evaluated as second or subsequent line treatments in extensive stage disease and later in combination with EP in the first-line setting. Recently two randomized phase III trials have demonstrated statistically improved OS with addition of a programmed death ligand-1 (PD-L1) inhibitor to EP. As a result, the standard of care for newly diagnosed patients with extensive-stage SCLC has changed for the first time in decades. However, many patients do not derive benefit from the addition of a PD-L1 inhibitor to EP. In this review we discuss first-line trials of chemoimmunotherapy in extensive stage SCLC and summarize data on second and subsequent line treatment with immune checkpoint inhibitors in immunotherapy-naïve patients. Additionally, we discuss potential biomarkers that could be utilized to select for which patients derive benefit from addition of a PD-L1 inhibitor to EP and propose ways to improve on first-line chemoimmunotherapy.

Cecal Volvulus as a Rare Complication of Osimertinib Dosed at 160 mg in Patients With EGFR-Mutant Non-small Cell Lung Cancer

Background: Osimertinib is a 3rd-generation tyrosine kinase inhibitor (TKI) that blocks the epidermal growth factor receptor (EGFR) in non-small lung cancer (NSCLC) and has dramatically improved outcomes for patients with EGFR mutations. While gastrointestinal complications such as diarrhea have been reported with EGFR inhibitors (due to off-target interactions with EGFR receptors within the gut lining), cecal volvulus is an extremely rare complication in advanced malignancy. To date, there are no reported cases associating cecal volvulus with any EGFR TKIs.

Case Presentation: In this case series, we present three cases of cecal volvulus among patients with EGFR-positive NSCLC patients treated with osimertinib dosed at double the standard 80 mg dose (160 mg daily). No patient was receiving concurrent chemotherapy or bevacizumab at the time of this described complication. In two cases where pathology was available for review, peritoneal carcinomatosis or intra-abdominal spread was not observed. In a retrospective evaluation of 101 patients treated with osimertinib in our institution, there was a statistically significant difference in the incidence of cecal volvulus among patients receiving osimertinib at 160 mg vs. patients receiving the 80 mg dose (27 vs. 0%; p < 0.001).

Conclusions: To our knowledge, these are the first cases to highlight a potentially important and serious gastrointestinal complication associated with the 160 mg dose of osimertinib.

Targeted therapies for ROS1-rearranged non-small cell lung cancer

ROS1 gene fusions account for approximately 1-2% of all cases of non-small cell lung cancer (NSCLC). Similarly to anaplastic lymphoma kinase (ALK)-positive NSCLC, patients with ROS1+ NSCLC tend to have minimal smoking and be of the female sex. In most cases, adenocarcinoma is the dominant histology. The ROS1 gene has homology to ALK and this structural similarity formed the basis for utilizing ALK inhibitors for ROS1+ NSCLC. On the basis of impressive progression-free survival of 19.2 months from the PROFILE 1001 trial, crizotinib obtained Food and Drug Administration (FDA) approval as first-line therapy for treatment of ROS1+ NSCLC. Since then, there has been a growing appreciation of the incidence of brain metastases in ROS1+ NSCLC and rates of central nervous system progression on crizotinib. Additionally, appreciation of novel resistance mechanisms to crizotinib has led to the development of newer tyrosine kinase inhibitors (TKIs). In this review, we highlight known and emerging TKIs for the management of ROS1+ NSCLC.

Clinicopathologic Characteristics, Treatment Outcomes, and Acquired Resistance Patterns of Atypical EGFR Mutations and HER2 Alterations in Stage IV Non-Small-Cell Lung Cancer

BACKGROUND

The clinicopathologic characteristics, acquired resistance patterns, and outcomes among patients with atypical EGFR mutations and HER2 alterations remain underexplored.

PATIENTS AND METHODS

A single-center retrospective review was conducted. Oncogenes assessed include typical EGFR (t-EGFR; exon 19 del and L858R), atypical EGFR (a-EGFR; G719X, exon 20, L861Q), HER2 (exon 19, exon 20, amplifications), gene fusions (ALK, ROS1, RET), RAS (KRAS, NRAS), and RAF (BRAF V600E). Progression-free survival (PFS), overall survival (OS), disease control rate, and objective response rate (Response Evaluation Criteria in Solid Tumors 1.1) were collected.

RESULTS

Among 570 patients, we found 55 a-EGFR mutations (13 G719X, 38 exon 20, 4 L861Q) and 31 HER2 alterations (2 exon 19 mutations, 27 exon 20 insertions, 2 amplifications). Patients with EGFR and HER2 alterations had increased lung and bone metastases relative to patients with gene fusions, RAS/RAF mutations, and no identified driver oncogenes (P < .001). Patients with EGFR exon 20 insertions had a median PFS to EGFR tyrosine kinase inhibitors (TKIs) of 5 months and an OS of 16 months-significantly worse than exon 19 del and L858R (Bonferroni correction; P < .001), but not G719X or L861Q. Relative to t-EGFR mutations, T790M and MET amplification occurred less frequently as acquired resistance mechanisms among a-EGFR samples (P < .001). Ten patients with a-EGFR mutations and HER2 alterations received single-agent immune checkpoint inhibitors (ICIs) with no radiographic responses and a median PFS of 2 months.

CONCLUSION

EGFR and HER2-mutated NSCLC have a high rate of synchronous lung and bone metastases. Patients with a-EGFR mutations have inferior responses to EGFR-directed therapies with lower rates of acquired T790M and MET amplification. Responses to ICIs are uniformly poor. Novel therapeutic approaches are needed.

Temozolomide plus PARP Inhibition in Small-Cell Lung Cancer: Could Patient-Derived Xenografts Accelerate Discovery of Biomarker Candidates?

Effective options are limited for patients with small-cell lung cancer who develop progressive disease during or after etoposide plus platinum-based therapy. In this issue of Cancer Discovery, Farago and colleagues highlight the data for temozolomide plus olaparib in this patient population and demonstrate the potential to accelerate biomarker discovery through co-clinical trials utilizing patient-derived xenografts.See related article by Farago et al., p. 1372.

A Changing of the Guard: Immune Checkpoint Inhibitors With and Without Chemotherapy as First Line Treatment for Metastatic Non-small Cell Lung Cancer

Inhibitory antibodies targeting programmed death protein 1 (PD-1) and programmed death ligand 1 (PD-L1) have resulted in improved outcomes for many patients with metastatic non-small cell lung cancer in (NSCLC) in the second-line setting due to their ability to lead to prolonged anti-tumor immune responses. Combining these immunotherapies with platinum-based chemotherapy as first-line treatment has resulted in improved response rates and increased survival when compared to platinum-based chemotherapy alone. Certain patient populations may even benefit from immune checkpoint inhibitors as monotherapy in the first-line setting. The PD-1 inhibitor pembrolizumab is approved as monotherapy or in combination with platinum + pemetrexed for most newly diagnosed patients with metastatic NSCLC, excluding those with a targetable oncogene such as ALK and EGFR. The PD-L1 inhibitor atezolizumab is also approved in combination with bevacizumab + carboplatin + paclitaxel for the same population, with some parts of the world also approving this regimen for patients with ALK rearrangements or EGFR activating mutations. However, there are many other chemo-immunotherapy regimens that have been evaluated as initial treatment in metastatic NSCLC. Additionally, combinations of PD-1 axis inhibitors with cytotoxic T lymphocyte antigen-4 inhibitors have been examined, although none are yet approved. Here we review the clinical data in support of the current first-line approaches across histologies and biomarker subtypes, as well as highlight future research directions revealed by the current data.

Natural History and Factors Associated with Overall Survival in Stage IV ALK-Rearranged Non-Small Cell Lung Cancer

INTRODUCTION

Clinical variables describing the natural history and longitudinal therapy outcomes of stage IV anaplastic lymphoma kinase gene rearrangement positive (ALK-positive) NSCLC and their relationship with long-term overall survival (OS) have not previously been described in detail.

METHODS

Patients with stage IV NSCLC treated with an ALK inhibitor at the University of Colorado Cancer Center from 2009 through November 2017 were identified retrospectively. OS curves were constructed by using Kaplan-Meier methods. Multivariate Cox proportional hazard analysis was used to determine the relationship of variables with OS.

RESULTS

Of the 110 patients with ALK-positive NSCLC who were identified, 105 received crizotinib as their initial ALK inhibitor. With a median follow-up time of 47 months, the median OS time from diagnosis of stage IV disease was 81 months (6.8 years). Brain metastases at diagnosis of stage IV disease (hazard ratio = 1.01, p = 0.971) and year of stage IV presentation (p = 0.887) did not influence OS. More organs with tumor at diagnosis of stage IV disease was associated with worse OS (HR = 1.49 for each additional organ with disease, including the CNS [p = 0.002]). Each additional month of pemetrexed-based therapy was associated with a 7% relative decrease in risk of death.

CONCLUSION

Patients with stage IV ALK-positive NSCLC can have prolonged OS. Brain metastases at diagnosis of stage IV disease does not influence OS. Having more organs involved with tumor at stage IV presentation is associated with worse outcomes. Prolonged benefit from pemetrexed is associated with better outcomes.

Antibody drug conjugates in thoracic malignancies

Antibody drug conjugates (ADCs) have the potential to alter the efficacy: toxicity ratio of cytotoxic therapy utilizing surface markers on cancer cells as antibody targets to preferentially deliver toxic payloads to tumor cells while limiting systemic toxicity. Multiple ADCs, differing in their antibody targets, cytotoxic payloads and linker molecules are currently being evaluated in non-small-cell lung cancer, small-cell lung cancer and malignant pleural mesothelioma. Here we review the available data in thoracic malignancies and the potential issues influencing the efficacy and toxicity of these approaches.

Efficacy of a high potency O1 Manisa monovalent vaccine against heterologous challenge with foot-and-mouth disease virus of O/SEA/Mya-98 lineage in sheep

Potency tests for commercial oil-adjuvanted foot-and-mouth disease (FMD) vaccines are usually carried out in cattle, using a full dose (2 ml) of vaccine and homologous virus challenge. However, in sheep the recommended vaccine dose is half of the cattle dose (1 ml) and most vaccines have not been potency tested for this species, especially with heterologous viruses. To determine the efficacy of a high potency (>6PD₅₀) FMD virus (FMDV) O1Manisa vaccine in sheep, we carried out a study using a heterologous FMDV (FMDV O/SKR/2010 - Mya-98 strain) challenge. Groups of seven animals each were vaccinated with 2×, 1×, 1/2× or 1/4× dose (2 ml, 1 ml, 0.5 ml or 0.25 ml respectively) and challenged at 7 days post vaccination (dpv). Only 3 of the 7 sheep in the group vaccinated with 2 ml were protected. With 2 additional groups, receiving double or single doses and challenged at 14 dpv, 4 of 7 sheep were protected in each group. None of the sheep had measurable neutralising antibodies against the vaccine or challenge virus at 7 dpv. However, all vaccinated animals challenged at 14 dpv had a homologous neutralising response against FMDV O1 Manisa on the day of challenge and all but one animal also had a heterologous response to FMDV O/SKR/2010. Infectious FMDV and viral RNA could be found in nasal swabs between 1 and 6 days post challenge (dpc) in most vaccinated sheep, but those vaccinated with higher doses or challenged at 14 dpv showed significant decreases in the level of FMDV detection. Intermittent virus shedding was noticed between 1 and 35 dpc in all vaccinated groups, but persistent infection could be demonstrated only in 4 sheep (20%). This study showed that at the recommended dose, a high potency (>6 PD₅₀) FMDV O1Manisa vaccine does not protect sheep against a heterologous challenge at 7 dpv. However, partial protection was observed when a double dose was used at 7 dpv or when double or single dose vaccinated sheep were challenged at 14 dpv.

Infection Dynamics of Foot-and-Mouth Disease Virus in Cattle Following Intranasopharyngeal Inoculation or Contact Exposure

For the purpose of developing an improved experimental model for studies of foot-and-mouth disease virus (FMDV) infection in cattle, three different experimental systems based on natural or simulated natural virus exposure were compared under standardized experimental conditions. Ante-mortem infection dynamics were characterized in cattle exposed to FMDV through a novel, simulated natural intranasopharyngeal (INP) inoculation system or through standardized and controlled systems of within- or between-species direct contact exposure (cattle-to-cattle or pig-to-cattle). All three systems were efficient in causing synchronous, generalized foot-and-mouth disease in cattle exposed to one of three different strains of FMDV representing serotypes O, A and Asia1. There was more within-group variation in the timing of clinical infection following natural and simulated natural virus exposure systems when compared with the conventionally used system of needle inoculation (intraepithelial lingual inoculation). However, the three optimized exposure systems described herein have the advantage of closely simulating field conditions by utilizing natural routes of primary infection, thereby facilitating engagement of mucosal host defence mechanisms. Overall, it is concluded that INP inoculation and standardized systems of direct contact exposure provide effective alternatives to conventional (needle) inoculation systems for studies in which it is desirable to simulate the natural biology of FMDV infection.

Early Detection of Foot-And-Mouth Disease Virus from Infected Cattle Using A Dry Filter Air Sampling System

Foot-and-mouth disease (FMD) is a highly contagious livestock disease of high economic impact. Early detection of FMD virus (FMDV) is fundamental for rapid outbreak control. Air sampling collection has been demonstrated as a useful technique for detection of FMDV RNA in infected animals, related to the aerogenous nature of the virus. In the current study, air from rooms housing individual (n = 17) or two groups (n = 4) of cattle experimentally infected with FDMV A24 Cruzeiro of different virulence levels was sampled to assess the feasibility of applying air sampling as a non-invasive, screening tool to identify sources of FMDV infection. Detection of FMDV RNA in air was compared with first detection of clinical signs and FMDV RNA levels in serum and oral fluid. FMDV RNA was detected in room air samples 1-3 days prior (seven animals) or on the same day (four animals) as the appearance of clinical signs in 11 of 12 individually housed cattle. Only in one case clinical signs preceded detection in air samples by one day. Overall, viral RNA in oral fluid or serum preceded detection in air samples by 1-2 days. Six individually housed animals inoculated with attenuated strains did not show clinical signs, but virus was detected in air in one of these cases 3 days prior to first detection in oral fluid. In groups of four cattle housed together, air detection always preceded appearance of clinical signs by 1-2 days and coincided more often with viral shedding in oral fluid than virus in blood. These data confirm that air sampling is an effective non-invasive screening method for detecting FMDV infection in confined to enclosed spaces (e.g. auction barns, milking parlours). This technology could be a useful tool as part of a surveillance strategy during FMD prevention, control or eradication efforts.

An Integrative Analysis of Foot-and-Mouth Disease Virus Carriers in Vietnam Achieved Through Targeted Surveillance and Molecular Epidemiology

Foot-and-mouth disease (FMD) is a major constraint to transboundary trade in animal products, yet much of its natural ecology and epidemiology in endemic regions is still poorly understood. To address this gap, a multidisciplinary, molecular and conventional epidemiological approach was applied to an investigation of endemic FMD in Vietnam. Within the study space, it was found that 22.3% of sampled ruminants had previously been infected with FMD virus (FMDV), of which 10.8% were persistent, asymptomatic carriers (2.4% of the total population). Descriptive data collected from targeted surveillance and a farm questionnaire showed a significantly lower prevalence of FMDV infection for dairy farms. In contrast, farms of intermediate size and/or history of infection in 2010 were at increased risk of FMD exposure. At the individual animal level, buffalo had the highest exposure risk (over cattle), and there was spatial heterogeneity in exposure risk at the commune level. Conversely, carrier prevalence was higher for beef cattle, suggesting lower susceptibility of buffalo to persistent FMDV infection. To characterize virus strains currently circulating in Vietnam, partial FMDV genomic (VP1) sequences from carrier animals collected between 2012 and 2013 (N = 27) and from FMDV outbreaks between 2009 and 2013 (N = 79) were compared by phylogenetic analysis. Sequence analysis suggested that within the study period, there were two apparent novel introductions of serotype A viruses and that the dominant lineage of serotype O in Vietnam shifted from SEA/Mya-98 to ME-SA/PanAsia. FMDV strains shared close ancestors with FMDV from other South-East Asian countries indicating substantial transboundary movement of the predominant circulating strains. Close genetic relationships were observed between carrier and outbreak viruses, which may suggest that asymptomatic carriers of FMDV contribute to regional disease persistence. Multiple viral sequences obtained from carrier cattle over a 1-year period had considerable within-animal genetic variation, indicating within-host virus evolution.

Virus-host interactions in persistently FMDV-infected cells derived from bovine pharynx

Foot-and-mouth disease virus (FMDV) produces a disease in cattle characterized by vesicular lesions and a persistent infection with asymptomatic low-level production of virus in pharyngeal tissues. Here we describe the establishment of a persistently infected primary cell culture derived from bovine pharynx tissue (PBPT) infected with FMDV serotype O1 Manisa, where surviving cells were serially passed until a persistently infected culture was generated. Characterization of the persistent virus demonstrated changes in its plaque size, ability to grow in different cell lines, and change in the use of integrins as receptors, when compared with the parental virus. These results demonstrate the establishment of persistently infected PBPT cell cultures where co-adaptation has taken place between the virus and host cells. This in vitro model for FMDV persistence may help further understanding of the molecular mechanisms of the cattle carrier state.

Detection of Foot-and-mouth Disease Virus RNA and Capsid Protein in Lymphoid Tissues of Convalescent Pigs Does Not Indicate Existence of a Carrier State

A systematic study was performed to investigate the potential of pigs to establish and maintain persistent foot-and-mouth disease virus (FMDV) infection. Infectious virus could not be recovered from sera, oral, nasal or oropharyngeal fluids obtained after resolution of clinical infection with any of five FMDV strains within serotypes A, O and Asia-1. Furthermore, there was no isolation of live virus from tissue samples harvested at 28-100 days post-infection from convalescent pigs recovered from clinical or subclinical FMD. Despite lack of detection of infectious FMDV, there was a high prevalence of FMDV RNA detection in lymph nodes draining lesion sites harvested at 35 days post-infection, with the most frequent detection recorded in popliteal lymph nodes (positive detection in 88% of samples obtained from non-vaccinated pigs). Likewise, at 35 dpi, FMDV capsid antigen was localized within follicles of draining lymph nodes, but without concurrent detection of FMDV non-structural protein. There was a marked decline in the detection of FMDV RNA and antigen in tissue samples by 60 dpi, and no antigen or viral RNA could be detected in samples obtained at 100 dpi. The data presented herein provide the most extensive investigation of FMDV persistence in pigs. The overall conclusion is that domestic pigs are unlikely to be competent long-term carriers of infectious FMDV; however, transient persistence of FMDV protein and RNA in lymphoid tissues is common following clinical or subclinical infection.

Body mass index, diabetes, and triple-negative breast cancer prognosis

Higher body mass index (BMI) and diabetes are associated with worse breast cancer prognosis. However, few studies have focused on triple-negative breast cancer (TNBC). The goal of this study is to examine this association in a cohort of patients with TNBC. We retrospectively reviewed 501 consecutive patients with TNBC seen at the Washington University Breast Oncology Clinic. Cox proportional hazard models were used to determine the relationship between BMI and diabetes at diagnosis with overall survival (OS) and disease free survival (DFS). Four hundred and forty-eight patients had BMI recorded and 71 patients had diabetes. The median age at diagnosis was 53 (23-98) years and follow-up was 40.1 months (IQR 25.2-62.9). Baseline BMI and diabetes were not associated with OS or DFS. OS hazard ratios (HRs) for patients who were overweight (BMI 25.0-29.99), with class I obesity (BMI 30-34.99), or BMI ≥35 were 1.22 (CI 0.78-1.91), 0.92 (CI 0.59-1.43), and 1.16 (CI 0.70-1.90), respectively. The HRs for DFS in patients who were overweight, with class I obesity, or BMI ≥35 were 1.01 (CI 0.65-1.56), 0.94 (CI 0.60-1.47), and 0.99 (CI 0.63-1.57), respectively. Similarly, the HRs for diabetics were 1.27 (CI 0.82-1.96) for OS and 0.98 (CI 0.64-1.51) for DFS. Obesity and diabetes did not significantly affect survival for patients with TNBC in this study.

Racial differences in outcomes of triple-negative breast cancer

African American (AA) women have a higher incidence of triple-negative breast cancer (TNBC: negative for the expression of estrogen receptor, progesterone receptor, and HER2 gene amplification) than Caucasian (CA) women, explaining in part their higher breast cancer mortality. However, there have been inconsistent data in the literature regarding survival outcomes of TNBC in AA versus CA women. We performed a retrospective chart review on 493 patients with TNBC first seen at the Washington University Breast Oncology Clinic (WUBOC) between January 2006 and December 2010. Analysis was done on 490 women (30 % AA) for whom follow-up data was available. The median age at diagnosis was 53 (23-98) years and follow-up time was 27.2 months. There was no significant difference between AA and CA women in the age of diagnosis, median time from abnormal imaging to breast biopsy and from biopsy diagnosis to surgery, duration of follow-up, tumor stage, grade, and frequency of receiving neoadjuvant or adjuvant chemotherapy and pathologic complete response rate to neoadjuvant chemotherapy. There was no difference in disease free survival (DFS) and overall survival (OS) between AA and CA groups by either univariate or multivariate analysis that included age, race, and stage. The hazard ratio for AA women was 1.19 (CI 0.80-1.78, p = 0.39) and 0.91 (CI 0.62-1.35, p = 0.64) for OS and DFS, respectively. Among the 158 patients who developed recurrence or presented with stage IV disease (AA: n = 36, CA: n = 122), no racial differences in OS were observed. We conclude that race did not significantly affect the clinical presentation and outcome of TNBC in this single center study where patients received similar therapy and follow-up.

Emergence of fairness in repeated group interactions

Often groups need to meet repeatedly before a decision is reached. Hence, most individual decisions will be contingent on decisions taken previously by others. In particular, the decision to cooperate or not will depend on one's own assessment of what constitutes a fair group outcome. Making use of a repeated N-person prisoner's dilemma, we show that reciprocation towards groups opens a window of opportunity for cooperation to thrive, leading populations to engage in dynamics involving both coordination and coexistence, and characterized by cycles of cooperation and defection. Furthermore, we show that this process leads to the emergence of fairness, whose level will depend on the dilemma at stake.

The early pathogenesis of foot-and-mouth disease in cattle after aerosol inoculation. Identification of the nasopharynx as the primary site of infection

To characterize the early events of foot-and-mouth disease virus (FMDV) infection in cattle subsequent to simulated natural exposure, 16 steers were aerosol inoculated with FMDV and euthanized at various times. Samples were collected from each steer antemortem (serum, nasal swabs, and oral swabs) and postmortem (up to 40 tissues per animal) and screened for FMDV by virus isolation and for FMDV RNA by real-time reverse transcription polymerase chain reaction. Tissues that tested positive for FMDV or viral RNA were examined by immunohistochemistry and multichannel immunofluorescence microscopy. In previremic steers, FMDV was most consistently localized to nasopharyngeal tissues, thereby indicating this region as the most important site of primary viral replication. The earliest site of microscopic localization of FMDV antigens was the lymphoid follicle-associated epithelium of the pharyngeal mucosa-associated lymphoid tissue of the nasopharynx at 6 hours postaerosolization. At early time points after aerosol inoculation, viral antigens colocalized with cytokeratin-positive pharyngeal epithelial cells; intraepithelial FMDV-negative, MHCII/CD11c-double-positive dendritic cells were present in close proximity to FMDV-positive cells. Onset of viremia coincided with marked increase of viral loads in pulmonary tissues and with substantial decrease of viral detection in nasopharyngeal tissues. These data indicate that subsequent to aerogenous exposure to FMDV, the temporally defined critical pathogenesis events involve (1) primary replication in epithelial cells of the pharyngeal mucosa-associated lymphoid tissue crypts and (2) subsequent widespread replication in pneumocytes in the lungs, which coincides with (3) the establishment of sustained viremia.

Bulk materials made of silicon cage clusters doped with Ti, Zr, or Hf

We investigate the feasibility of assembling the exceptionally stable isovalent X@Si(16) (X = Ti, Zr and Hf) nanoparticles to form new bulk materials. We use first-principles density functional theory. Our results predict the formation of stable, wide band-gap materials crystallizing in HCP structures in which the cages bind weakly, similar to fullerite. This study suggests new pathways through which endohedral cage clusters may constitute a viable means toward the production of synthetic materials with pre-defined physical and chemical properties.

Progenitor cell self-renewal and cyclic neutropenia

OBJECTIVES

Cyclic neutropenia (CN) is a rare genetic disorder where patients experience regular cycling of numbers of neutrophils and various other haematopoietic lineages. The nadir in neutrophil count is the main source of problems due to risk of life-threatening infections. Patients with CN benefit from granulocyte colony stimulating factor therapy, although cycling persists. Mutations in neutrophil elastase gene (ELA2) have been found in more than half of patients with CN. However, neither connection between phenotypic expression of ELA2 and CN nor the mechanism of cycling is known.

MATERIALS AND METHODS

Recently, a multicompartment model of haematopoiesis that couples stem cell replication with marrow output has been proposed. In the following, we couple this model of haematopoiesis with a linear feedback mechanism via G-CSF.

RESULTS

We propose that the phenotypic effect of ELA2 mutations leads to reduction in self-renewal of granulocytic progenitors. The body responds by overall relative increase of G-CSF and increasing progenitor cell self-renewal, leading to cell count cycling.

CONCLUSION

The model is compatible with available experimental data and makes testable predictions.

Reacting differently to adverse ties promotes cooperation in social networks

We investigate how diversity in individual responses to unwanted interactions affects the evolution of cooperation modeled as a 2-person prisoner's dilemma. We combine adaptive networks and evolutionary game theory, showing analytically how the coevolution of social dynamics, network dynamics, and behavioral differences benefit the entire community even though myopic individuals still act in their own interest. As defectors are wiped out, surviving cooperators maintain the full diversity of behavioral types, establishing cooperation as a robust evolutionary strategy. The present framework can be used in other problems where the feedback between topology and dynamics affects the overall behavior of the system.

The evolution of norms

We develop a two-level selection model in the framework of evolutionary game theory, in which fitness selection at different levels is related to different games. We consider an archipelago of communities, such that selection operates at an individual level inside each community and at a group level whenever evolution of communities is at stake. We apply this model to the evolution of social norms, an open problem of ubiquitous importance in social science. Extensive statistical analysis of our results lead to the emergence of one common social norm, of which the evolutionary outcomes in different communities are simple by-products. This social norm induces reputation-based cooperative behavior, and reflects the evolutionary propensity to promote simple, unambiguous norms, in which forgiveness and repent are welcome, while punishment is implacable.

A new route to the evolution of cooperation

The Prisoner's Dilemma (PD) constitutes a widely used metaphor to investigate problems related to the evolution of cooperation. Whenever evolution takes place in well-mixed populations engaged in single rounds of the PD, cooperators cannot resist invasion by defectors, a feature, which is somewhat alleviated whenever populations are spatially distributed. In both cases the populations are characterized by a homogeneous pattern of connectivity, in which every individual is equivalent, sharing the same number of neighbours. Recently, compelling evidence has been accumulated on the strong heterogeneous nature of the network of contacts between individuals in populations. Here we describe the networks of contacts in terms of graphs and show that heterogeneity provides a new mechanism for cooperation to survive. Specifically, we show that cooperators are capable of exploring the heterogeneity of the population structure to become evolutionary competitive. As a result, cooperation becomes the dominating trait in scale-free networks of contacts in which the few highly connected individuals are directly inter-connected, in this way contributing to self-sustain cooperation.

Epidemic spreading and cooperation dynamics on homogeneous small-world networks

We introduce a class of small-world networks--homogeneous small-worlds--which, in contrast with the well-known Watts-Strogatz small-worlds, exhibit a homogeneous connectivity distribution, in the sense that all nodes have the same number of connections. This feature allows the investigation of pure small-world effects, detached from any associated heterogeneity. Furthermore, we use at profit the remarkable similarity between the properties of homogeneous small worlds and the heterogeneous small-worlds of Watts-Strogatz to assess the separate roles of heterogeneity and small-world effects. We investigate the dependence on these two mechanisms of the threshold for epidemic outbreaks and also of the coevolution of cooperators and defectors under natural selection. With respect to the well-studied regular homogeneous limits, we find a subtle interplay between these mechanisms. While they both contribute to reduce the threshold for an epidemic outburst, they exhibit opposite behavior in the evolution of cooperation, such that the overall results mask the true nature of their individual contribution to this process.