Reasons for multiple biologic and targeted synthetic DMARD switching and characteristics of treatment refractory rheumatoid arthritis.

OBJECTIVE: Switching biologic and targeted synthetic DMARD (b/tsDMARD) medications occurs commonly in RA patients, however data are limited on the reasons for these changes. The objective of the study was to identify and categorize reasons for b/tsDMARD switching and investigate characteristics associated with treatment refractory RA. METHODS: In a multi-hospital RA electronic health record (EHR) cohort, we identified RA patients prescribed ≥1 b/tsDMARD between 2001 and 2017. Consistent with the EULAR "difficult to treat" (D2T) RA definition, we further identified patients who discontinued ≥2 b/tsDMARDs with different mechanisms of action. We performed manual chart review to determine reasons for medication discontinuation. We defined "treatment refractory" RA as not achieving low disease activity (<3 tender or swollen joints on <7.5 mg of daily prednisone equivalent) despite treatment with two different b/tsDMARD mechanisms of action. We compared demographic, lifestyle, and clinical factors between treatment refractory RA and b/tsDMARD initiators not meeting D2T criteria. RESULTS: We identified 6040 RA patients prescribed ≥1 b/tsDMARD including 404 meeting D2T criteria. The most common reasons for medication discontinuation were inadequate response (43.3 %), loss of efficacy (25.8 %), and non-allergic adverse events (13.7 %). Of patients with D2T RA, 15 % had treatment refractory RA. Treatment refractory RA patients were younger at b/tsDMARD initiation (mean 47.2 vs. 55.2 years, p < 0.001), more commonly female (91.8% vs. 76.1 %, p = 0.006), and ever smokers (68.9% vs. 49.9 %, p = 0.005). No RA clinical factors differentiated treatment refractory RA patients from b/tsDMARD initiators. CONCLUSIONS: In a large EHR-based RA cohort, the most common reasons for b/tsDMARD switching were inadequate response, loss of efficacy, and nonallergic adverse events (e.g. infections, leukopenia, psoriasis). Clinical RA factors were insufficient for differentiating b/tsDMARD responders from nonresponders.

Association of Somatic TET2 Mutations With Giant Cell Arteritis.

OBJECTIVE: Giant cell arteritis (GCA) is an age-related vasculitis. Prior studies have identified an association between GCA and hematologic malignancies (HMs). How the presence of somatic mutations that drive the development of HMs, or clonal hematopoiesis (CH), may influence clinical outcomes in GCA is not well understood. METHODS: To examine an association between CH and GCA, we analyzed sequenced exomes of 470,960 UK Biobank (UKB) participants for the presence of CH and used multivariable Cox regression. To examine the clinical phenotype of GCA in patients with and without somatic mutations across the spectrum of CH to HM, we performed targeted sequencing of blood samples and electronic health record review on 114 patients with GCA seen at our institution. We then examined associations between specific clonal mutations and GCA disease manifestations. RESULTS: UKB participants with CH had a 1.48-fold increased risk of incident GCA compared to UKB participants without CH. GCA risk was highest among individuals with cytopenia (hazard ratio [HR] 2.98, P = 0.00178) and with TET2 mutation (HR 2.02, P = 0.00116). Mutations were detected in 27.2% of our institutional GCA cohort, three of whom had HM at GCA diagnosis. TET2 mutations were associated with vision loss in patients with GCA (odds ratio 4.33, P = 0.047). CONCLUSIONS: CH increases risk for development of GCA in a genotype-specific manner, with the greatest risk being conferred by the presence of mutations in TET2. Somatic TET2 mutations likewise increase the risk of GCA-associated vision loss. Integration of somatic genetic testing in GCA diagnostics may be warranted in the future.

Effectiveness and tolerability of antifibrotics in rheumatoid arthritis-associated interstitial lung disease.

OBJECTIVE: Our aim was to investigate the effectiveness and tolerability of antifibrotics in a real-world cohort of patients with rheumatoid arthritis-associated interstitial lung diseases (RA-ILD). METHODS: In this retrospective cohort study, we identified RA-ILD patients initiating antifibrotics at Mass General Brigham Integrated Health Care System, a large multi-hospital healthcare system in Boston, MA, USA. We used electronic query to identify all patients with at least 2 RA diagnosis codes and a prescription for either nintedanib or pirfenidone (2014-2023). All analyzed patients met 2010 American College of Rheumatology/European Alliance of Associations for Rheumatology classification criteria for RA and had definite RA-ILD according to Bongartz criteria. Data regarding pulmonary function test (PFT) results, adverse events (AEs), tolerability, and clinical data were collected. A linear mixed model with random intercept was used to compare the within-patient trajectory of the percent predicted forced vital capacity (FVCpp) within 18-months before to 18-months after antifibrotic initiation among those with these PFT data. Lung transplant-free survival and drug retention was estimated in a Kaplan-Meier analysis and a Cox regression analysis was performed to identify independent baseline factors associated with lung transplant or mortality. RESULTS: We analyzed 74 patients with RA-ILD that initiated antifibrotics (mean age 67.8 years, 53 % male); 40 patients initiated nintedanib and 34 initiated pirfenidone. Median follow-up was 89 weeks (min 4, max 387). There was a significant improvement in the estimated slope of FVCpp after antifibrotic initiation (-0.3 % per year after initiation compared to -6.2 % per year before antifibrotic initiation, p = 0.03). Nintedanib and pirfenidone had similar FVCpp trajectory. Twenty-six patients (35 %) died and 4 (5 %) had undergone lung transplantation during follow-up. Male sex and heavy smoking were each associated with the composite outcome of lung transplant or mortality. AEs were reported in 41 (55 %) patients, with gastrointestinal (GI) AEs being most common (n = 30). The initial antifibrotic was discontinued in 34 (46 %) patients mostly due to GI AEs (n = 19). The median drug retention time was 142 weeks (95 %CI 56, 262) with no difference between nintedanib and pirfenidone (p = 0.68). CONCLUSION: In this first real-world study of antifibrotic use dedicated to RA-ILD, antifibrotic initiation was associated with a modestly improved trajectory of FVCpp. AEs were frequently reported, particularly GI, and discontinuation was common. However, lung transplant and mortality rates were still high, emphasizing the need for further therapeutic strategies in patients with severe RA-ILD. These real-world data complement previous trial data that investigated efficacy and safety.

Factors Associated With Diagnostic Delay in Axial Spondyloarthritis: Impact of Clinical Factors and Social Vulnerability.

OBJECTIVE: Patients with axial spondyloarthritis (axSpA) often experience significant delay between symptom onset and diagnosis for reasons that are incompletely understood. We investigated associations between demographic, medical, and socioeconomic factors and axSpA diagnostic delay. METHODS: We identified patients meeting modified New York criteria for ankylosing spondylitis (AS) or 2009 Assessment of Spondyloarthritis International Society criteria for axSpA in the Mass General Brigham health care system between December 1990 and October 2021. We determined the duration of diagnostic delay, defined as the duration of back pain symptoms reported at diagnosis, as well as disease manifestations and specialty care prior to diagnosis from the electronic health record. We obtained each patient's Social Vulnerability Index (SVI) by mapping their address to the US Centers for Disease Control SVI Atlas. We examined associations among disease manifestations, SVI, and diagnostic delay using ordinal logistic regression. RESULTS: Among 554 patients with axSpA who had a median diagnostic delay of 3.8 years (interquartile range 1.1-10), peripheral arthritis (odds ratio [OR] 0.65, 95% confidence interval [CI] 0.45-0.93) and older age at symptom onset (OR 0.83, 95% CI 0.78-0.88 per five years) were associated with shorter delay. AS at diagnosis (OR 1.85, 95% CI 1.30-2.63), a history of uveitis prior to diagnosis (OR 2.77, 95% CI 1.73-4.52), and higher social vulnerability (defined as national SVI 80th to 99th percentiles; OR 1.99, 95% CI 1.06-3.84) were associated with longer diagnostic delay. CONCLUSION: Older age at back pain onset and peripheral arthritis were associated with shorter delay, whereas uveitis was associated with longer diagnostic delay. Patients with higher socioeconomic vulnerability had longer diagnostic delay independent of clinical factors.

Rheumatoid arthritis, quantitative parenchymal lung features, and mortality among smokers.

OBJECTIVES: There have been limited investigations of the prevalence and mortality impact of quantitative computed tomography (QCT) parenchymal lung features in rheumatoid arthritis (RA). We examined the cross-sectional prevalence and mortality associations of QCT features, comparing RA and non-RA participants. METHODS: We identified participants with and without RA in COPDGene, a multicentre cohort study of current or former smokers. Using a k-nearest neighbor quantifier, high resolution CT chest scans were scored for percentage of normal lung, interstitial changes, and emphysema. We examined associations between QCT features and RA using multivariable linear regression. After dichotomizing participants at the 75th percentile for each QCT feature among non-RA participants, we investigated mortality associations by RA/non-RA status and quartile 4 vs quartiles 1-3 of QCT features using Cox regression. We assessed for statistical interactions between RA and QCT features. RESULTS: We identified 82 RA cases and 8820 non-RA comparators. In multivariable linear regression, RA was associated with higher percentage of interstitial changes (ß = 1.7 ± 0.5, p= 0.0008) but not emphysema (ß = 1.3 ± 1.7, p= 0.44). Participants with RA and >75th percentile of emphysema had significantly higher mortality than non-RA participants (HR 5.86, 95%CI 3.75-9.13) as well as RA participants (HR 5.56, 95%CI 2.71-11.38) with ≤75th percentile of emphysema. There were statistical interactions between RA and emphysema for mortality (multiplicative p= 0.014; attributable proportion 0.53, 95%CI 0.30-0.70). CONCLUSIONS: Using machine learning-derived QCT data in a cohort of smokers, RA was associated with higher percentage of interstitial changes. The combination of RA and emphysema conferred >5-fold higher mortality.

Prevalence and mortality associations of interstitial lung abnormalities in rheumatoid arthritis within a multicentre prospective cohort of smokers.

OBJECTIVE: To investigate the prevalence and mortality impact of interstitial lung abnormalities (ILAs) in RA and non-RA comparators. METHODS: We analysed associations between ILAs, RA, and mortality in COPDGene, a multicentre prospective cohort study of current and past smokers, excluding known interstitial lung disease (ILD) or bronchiectasis. All participants had research chest high-resolution CT (HRCT) reviewed by a sequential reading method to classify ILA as present, indeterminate or absent. RA cases were identified by self-report RA and DMARD use; non-RA comparators had neither an RA diagnosis nor used DMARDs. We examined the association and mortality risk of RA and ILA using multivariable logistic regression and Cox regression. RESULTS: We identified 83 RA cases and 8725 non-RA comparators with HRCT performed for research purposes. ILA prevalence was 16.9% in RA cases and 5.0% in non-RA comparators. After adjusting for potential confounders, including genetics, current/past smoking and other lifestyle factors, ILAs were more common among those with RA compared with non-RA [odds ratio 4.76 (95% CI 2.54, 8.92)]. RA with ILAs or indeterminate for ILAs was associated with higher all-cause mortality compared with non-RA without ILAs [hazard ratio (HR) 3.16 (95% CI 2.11, 4.74)] and RA cases without ILA [HR 3.02 (95% CI 1.36, 6.75)]. CONCLUSIONS: In this cohort of smokers, RA was associated with ILAs and this persisted after adjustment for current/past smoking and genetic/lifestyle risk factors. RA with ILAs in smokers had a 3-fold increased all-cause mortality, emphasizing the importance of further screening and treatment strategies for preclinical ILD in RA.

Migraine and the risk of cervical artery dissection: A systematic review and meta-analysis.

INTRODUCTION: Migraine is a common, disabling chronic pain condition possibly related to changes in endothelial and vascular structure and function. Several observational studies have suggested an elevated risk of cervical artery dissection (CeAD) in patients with a history of migraine. We aimed to investigate this potential association using systematic review and meta-analytic methods. PATIENTS AND METHODS: We utilized a pre-defined search protocol to identify and screen studies related to migraine and CeAD in PubMed, Embase, and the Web of Science Core Collection. We assessed the risk of bias and performed a meta-analysis of selected studies to assess the association between migraine and CeAD. We also performed subgroup analyses by migraine subtype, biological sex, and the use of stroke versus non-stroke controls. RESULTS: We identified 11 studies (N = 9857 patients) for inclusion in the meta-analysis. Meta-analysis showed an association between migraine and CeAD with an odds ratio of 1.74 (95%CI 1.38-2.19). There was high heterogeneity among the included studies (I2 = 61%). Publication bias was present but the Trim-Fill imputation suggested that the impact on results was likely minimal. Subgroup analyses revealed an association between migraine without aura and CeAD (OR 1.86, 95%CI 1.55-2.24) but not migraine with aura and CeAD (OR 1.15, 95%CI 0.71-1.88). There was no difference in the association between migraine and CeAD in men compared to women. DISCUSSION AND CONCLUSION: A history of migraine is associated with an increased risk of CeAD. Further studies are needed to elucidate the potential pathophysiologic mechanisms underlying this association.

Gene-respiratory disease interactions for rheumatoid arthritis risk.

OBJECTIVE: We aimed to identify gene by respiratory tract disease interactions that increase RA risk. METHODS: In this case-control study using the Mass General Brigham Biobank, we matched incident RA cases, confirmed by ACR/EULAR criteria, to four controls on age, sex, and electronic health record history. Genetic exposures included a validated overall genetic risk score (GRS) for RA, a Human Leukocyte Antigen (HLA) GRS for RA, and the MUC5B promoter variant, an established risk factor for RA-associated interstitial lung disease (ILD). Preceding respiratory tract diseases came from diagnosis codes (positive predictive value 86%). We estimated attributable proportions (AP) and multiplicative odds ratios (OR) with 95% confidence intervals (CI) for RA for each genetic and respiratory exposure using conditional logistic regression models, adjusting for potential confounders. RESULTS: We identified 653 incident RA cases and 2,607 matched controls (mean 54 years, 76% female). The highest tertile of the overall GRS and the HLA GRS were both associated with increased RA risk (OR 2.28, 95% CI 1.89,2.74; OR 2.02, 95% CI 1.67-2.45). ILD and the HLA GRS exhibited a synergistic relationship for RA risk (OR for both exposures 4.30, 95% CI 1.28,14.38; AP 0.51, 95% CI-0.16,1.18). Asthma and the MUC5B promoter variant also exhibited a synergistic interaction for seropositive RA (OR for both exposures 2.58, 95% CI 1.10,6.07; AP 0.62, 95% CI 0.24,1.00). CONCLUSION: ILD-HLA GRS and asthma-MUC5B promoter variant showed synergistic interactions for RA risk. Such interactions may prove useful for RA prevention and screening.

Autoantibodies against citrullinated and native proteins and prediction of rheumatoid arthritis-associated interstitial lung disease: A nested case-control study.

Background: To identify fine specificity anti-citrullinated protein antibodies (ACPA) associated with incident rheumatoid arthritis-associated interstitial lung disease (RA-ILD). Methods: This nested case-control study within the Brigham RA Sequential Study matched incident RA-ILD cases to RA-noILD controls on time of blood collection, age, sex, RA duration, and rheumatoid factor status. A multiplex assay measured ACPA and anti-native protein antibodies from stored serum prior to RA-ILD onset. Logistic regression models calculated odds ratios (OR) with 95% confidence intervals (CI) for RA-ILD, adjusting for prospectively-collected covariates. We estimated optimism-corrected area under the curves (AUC) using internal validation. Model coefficients generated a risk score for RA-ILD. Findings: We analyzed 84 incident RA-ILD cases (mean age 67 years, 77% female, 90% White) and 233 RA-noILD controls (mean age 66 years, 80% female, 94% White). We identified six fine specificity antibodies that were associated with RA-ILD. The antibody isotypes and targeted proteins were: IgA2 to citrullinated histone 4 (OR 0.08 per log-transformed unit, 95% CI 0.03-0.22), IgA2 to citrullinated histone 2A (OR 4.03, 95% CI 2.03-8.00), IgG to cyclic citrullinated filaggrin (OR 3.47, 95% CI 1.71-7.01), IgA2 to native cyclic histone 2A (OR 5.52, 95% CI 2.38-12.78), IgA2 to native histone 2A (OR 4.60, 95% CI 2.18-9.74), and IgG to native cyclic filaggrin (OR 2.53, 95% CI 1.47-4.34). These six antibodies predicted RA-ILD risk better than all clinical factors combined (optimism-corrected AUC=0·84 versus 0·73). We developed a risk score for RA-ILD combining these antibodies with the clinical factors (smoking, disease activity, glucocorticoid use, obesity). At 50% predicted RA-ILD probability, the risk scores both without (score=2·6) and with (score=5·9) biomarkers achieved specificity ≥93% for RA-ILD. Interpretation: Specific ACPA and anti-native protein antibodies improve RA-ILD prediction. These findings implicate synovial protein antibodies in the pathogenesis of RA-ILD and suggest clinical utility in predicting RA-ILD once validated in external studies. Funding: National Institutes of Health.

Risk of severe COVID-19 outcomes associated with rheumatoid arthritis and phenotypic subgroups: a retrospective, comparative, multicentre cohort study.

Background: Rheumatoid arthritis has been associated with severe COVID-19, but few studies have investigated how phenotypes of rheumatoid arthritis affect these associations. We aimed to investigate the associations between rheumatoid arthritis and phenotypes of interstitial lung disease, serostatus, and bone erosions with COVID-19 severity. Methods: We did a retrospective, comparative, multicentre cohort study at two large health-care systems (Mayo Clinic [19 hospitals and affiliated outpatient centres] and Mass General Brigham [14 hospitals and affiliated outpatient centres]) in the USA. Consecutive patients with rheumatoid arthritis meeting the 2010 American College of Rheumatology/European League Against Rheumatism classification criteria and who had COVID-19 between March 1, 2020, and June 6, 2021, were matched 1:5 on age, sex, and calendar date with patients without rheumatoid arthritis (comparators). Data were received from electronic health records from Mayo Clinic and Mass General Brigham. We examined subgroups of patients with rheumatoid arthritis by phenotypic features: rheumatoid arthritis-associated interstitial lung disease, seropositivity (for anti-cyclic citrullinated peptide, rheumatoid factor, or both), and bone erosions. Severe COVID-19 was a composite of hospitalisation or death. We used Cox regression to estimate hazard ratios (HR) for severe COVID-19, comparing rheumatoid arthritis and subgroups to the comparator group. Findings: We identified 582 patients with rheumatoid arthritis and 2875 matched comparators, all of whom had COVID-19 within the study dates. The mean age of those with rheumatoid arthritis was 62 [SD 14] years, 421 (72%) of 582 were women and 161 (28%) were men, 457 (79%) were White, 65 (11%) were Hispanic or Latino, and 41 (7%) were Black. Among patients with rheumatoid arthritis, 50 (9%) of 582 had interstitial lung disease, 388 (68%) of 568 were seropositive, and 159 (27%) of 582 had bone erosions. Severe COVID-19 occurred in 126 (22%) of 582 patients with rheumatoid arthritis versus 363 (13%) 2875 in the comparator group. Patients with rheumatoid arthritis had an HR of 1·75 (95% CI 1·45-2·10) for severe COVID-19 versus the comparator group. Patients with rheumatoid arthritis-associated interstitial lung disease had an HR of 2·50 (1·66-3·77) versus the comparator group for severe COVID-19. The risk for severe COVID-19 was also higher in patients with rheumatoid arthritis who were seropositive (HR 1·97 [95% CI 1·58-2·46]) or had erosive disease (1·93 [1·41-2·63]) than for those in the comparator group. Interpretation: Patients with rheumatoid arthritis have an increased risk of severe COVID-19 across phenotypic subgroups, especially among patients with interstitial lung disease. These findings suggest that rheumatoid arthritis with interstitial lung disease, or its treatment, might be a substantial contributor to severe COVID-19 outcomes for patients with rheumatoid arthritis. Funding: None.

Interstitial lung disease throughout the rheumatoid arthritis disease course.

PURPOSE OF REVIEW: To summarize the current understanding of rheumatoid arthritis-associated interstitial lung disease (RA-ILD) throughout the rheumatoid arthritis (RA) disease course from preclinical to established disease. RECENT FINDINGS: ILD is a serious extra-articular manifestation of RA. Multiple studies have demonstrated a high prevalence of both subclinical and clinical ILD throughout the RA disease course. Investigations of patients without RA have demonstrated an association between RA-related autoantibodies like anticitrullinated protein antibodies (ACPA) and interstitial abnormalities on lung imaging. A significant proportion of RA-ILD patients develop ILD prior to articular manifestations, suggesting that the lung plays a central role in RA development, perhaps through ACPA production. RA-ILD also occurs in early RA, when exuberant autoantibody production and systemic inflammation may propagate pulmonary disease activity. In patients with established RA, a high burden of subclinical and clinical ILD results in significant morbidity, mortality, and healthcare expenditure. Multiple epidemiologic and genetic risk factors, as well as serum biomarkers, have been associated with RA-ILD. SUMMARY: Subclinical and clinical ILD occur frequently in preclinical, early, and established RA and may play a key role in RA-related autoantibody production and disease progression. Further studies are needed to better understand the risk factors, prognosis, and potential therapies for RA-ILD.

A Retrospective Evaluation of Vemurafenib as Treatment for BRAF-Mutant Melanoma Brain Metastases.

BACKGROUND: RAF inhibitors are an effective therapy for patients with BRAF-mutant melanoma and brain metastasis. Efficacy data are derived from clinical studies enriched with physiologically fit patients; therefore, it is of interest to assess the real-world experience of vemurafenib in this population. Tumor-specific genetic variants that influence sensitivity to RAF kinase inhibitors also require investigation. METHODS: Records of patients with BRAF-mutant melanoma and brain metastases who were treated with vemurafenib were reviewed. Clinical data were extracted to determine extracranial and intracranial objective response rates, progression-free survival (PFS), overall survival (OS), and safety. A bait-capture, next-generation sequencing assay was used to identify mutations in pretreatment tumors that could explain primary resistance to vemurafenib. RESULTS: Among patients with intracranial disease treated with vemurafenib, 27 were included in survival analyses and 22 patients were assessable for response. The extracranial and intracranial objective response rates were 71% and 50%, respectively. Discordant responses were observed between extracranial and intracranial metastatic sites in 4 of 19 evaluable patients. Median PFS was 4.1 months (95% confidence interval [CI]: 2.6-7.9); median intracranial PFS was 4.6 months (95% CI: 2.7-7.9), median OS was 7.5 months (95% CI: 4.3-not reached), with a 30.4% 1-year OS rate. Outcomes were influenced by performance status. Vemurafenib was tolerable, although radiation-induced dermatitis occurred in some patients who received whole-brain radiotherapy. Adequate samples for next-generation sequencing analysis were available for seven patients. Melanomas categorized as "poorly sensitive" (≥20% tumor growth, new lesions, or ≤50% shrinkage for <4 months) harbored co-occurring mutations in genes predicted to activate the phosphatidylinositol 3-kinase-AKT (PI3K-AKT) pathway. CONCLUSION: Vemurafenib is highly active in BRAF-mutant melanoma brain metastases but has limited activity in patients with poor performance status. The safety and efficacy of concurrent radiotherapy and RAF inhibition requires careful clinical evaluation. Combination strategies blocking the MAPK and PI3K-AKT pathway may be warranted in a subset of patients. IMPLICATIONS FOR PRACTICE: Vemurafenib is active for BRAF-mutant intracranial melanoma metastases in an unselected patient population typical of routine oncologic practice. Patients with poor performance status appear to have poor outcomes despite vemurafenib therapy. Preliminary data indicate that co-occurring or secondary alterations in the phosphatidylinositol 3-kinase-AKT (PI3K-AKT) pathway are involved in resistance to RAF inhibition, thus providing a rationale for dual MAPK and PI3K-AKT pathway inhibition in this patient population.

Synthetic lethality in ATM-deficient RAD50-mutant tumors underlies outlier response to cancer therapy.

UNLABELLED: Metastatic solid tumors are almost invariably fatal. Patients with disseminated small-cell cancers have a particularly unfavorable prognosis, with most succumbing to their disease within two years. Here, we report on the genetic and functional analysis of an outlier curative response of a patient with metastatic small-cell cancer to combined checkpoint kinase 1 (CHK1) inhibition and DNA-damaging chemotherapy. Whole-genome sequencing revealed a clonal hemizygous mutation in the Mre11 complex gene RAD50 that attenuated ATM signaling which in the context of CHK1 inhibition contributed, via synthetic lethality, to extreme sensitivity to irinotecan. As Mre11 mutations occur in a diversity of human tumors, the results suggest a tumor-specific combination therapy strategy in which checkpoint inhibition in combination with DNA-damaging chemotherapy is synthetically lethal in tumor cells but not normal cells with somatic mutations that impair Mre11 complex function. SIGNIFICANCE: Strategies to effect deep and lasting responses to cancer therapy in patients with metastatic disease have remained difficult to attain, especially in early-phase clinical trials. Here, we present an in-depth genomic and functional genetic analysis identifying RAD50 hypomorphism as a contributing factor to a curative response to systemic combination therapy in a patient with recurrent, metastatic small-cell cancer.