Abstract
Purpose:
Cisplatin is a first-line chemotherapeutic for many cancers, but causes neurotoxicity including hearing loss, tinnitus, and peripheral sensory neuropathy. However, no study has comprehensively characterized risk factors for developing multiple (>1) severe neurotoxicities.
Experimental Design:
The relationship between multiple severe neurotoxicities and age, cumulative cisplatin dose, medical history, and lifestyle/behavioral factors was evaluated in 300 cisplatin-treated testicular cancer survivors using logistic regression. Case-control GWAS (cases: 104; controls: 196) was also performed.
Results:
Age at clinical examination (p=6.4x10−16) and cumulative cisplatin dose (p=5.4x10−4) were positively associated with multiple severe neurotoxicity risk, as were high serum platinum levels (p=0.02), tobacco use (ever smoker: p=0.001, current smoker: p=0.002), and hypertension (p=0.01) after adjustment for age and cumulative cisplatin dose. Individuals with multiple severe neurotoxicities were more likely to experience dizziness/vertigo (p=0.01), Raynaud phenomenon (p=3.7x10−9), and symptoms consistent with peripheral motor neuropathy (p=4.3x10−14) after age- and dose-adjustment. These patients also reported poorer overall health (p=2.7x10−5) and a greater use of psychotropic medications (p=0.06). GWAS identified no genome-wide significant SNPs. Gene-based association analysis identified RGS17 (p=3.9x10−5) and FAM20C (p=5.5x10−5) as near genome-wide significant. Decreased FAM20C expression was associated with increased cisplatin sensitivity in tumor cell lines.
Conclusion:
Certain survivors are more susceptible to cisplatin-induced neurotoxicity, markedly increasing likelihood of developing numerous neuro-otological symptoms that affect quality of life. Genome-wide analysis identified genetic variation in FAM20C as a potentially important risk factor.
Introduction
Cisplatin is a widely used anticancer drug implemented as standard-of-care therapy for multiple adult-onset and pediatric malignancies. Although cisplatin-based chemotherapy has resulted in relatively high five-year survival rates for many cancers (1), including testicular cancer (95%), hepatoblastoma (> 80%), medulloblastoma (70-80%), and osteosarcoma (60-80%), it also elicits adverse health outcomes, including ototoxicity, neurotoxicity, nephrotoxicity, cardiometabolic sequelae, and secondary malignancies (2, 3). Neurotoxicities in testicular cancer survivors include hearing loss with approximately 18% classified as severe to profound (4, 5), 15% of patients reporting severe tinnitus (6) and 12.5% noting severe symptoms of peripheral neuropathy (7). Since patients diagnosed with testicular cancer are typically young adults, individuals who develop persistent neurotoxicities will endure the long-term consequences for decades, ultimately reducing productivity and quality of life (8, 9).
Although cisplatin has been in clinical use for over 40 years, it remains difficult to identify those patients who may develop severe, persistent neurotoxicities. Previously, Kerns et al. (10) developed a score to evaluate the cumulative burden of morbidity (CBM) of cisplatin-based chemotherapy in 1,214 testicular cancer survivors, as well as a secondary score (CBM-Pt) that examined a subset of toxicities including peripheral sensory neuropathy, hearing damage, tinnitus, and kidney disease. However, this study did not explicitly identify risk factors and comorbidities associated with the CBM-Pt score.
Due to the high incidence of hearing loss, tinnitus, and peripheral sensory neuropathy in testicular cancer survivors following cisplatin-based chemotherapy and the previously noted associations between tinnitus and hearing loss (6), and tinnitus and sensory neuropathy (6), we propose that a subpopulation may be especially susceptible to developing multiple severe, persistent neurotoxicities. We characterize the incidence of this outcome in testicular cancer survivors enrolled in the Platinum Study (11), evaluating the influence of age, cisplatin-based chemotherapy, medical history, lifestyle/behavioral factors, and other risk factors. We also perform SNP-based and gene-based analyses to identify genetic predisposition to multiple severe cisplatin-induced neurotoxicities.
Materials and methods
Patient Selection
All patients were enrolled in the Platinum Study, a clinical investigation including eight centers in the U.S., Canada, and United Kingdom (2). Eligibility criteria were previously outlined (5, 7). Briefly, during routine follow-up, eligible testicular cancer survivors underwent extensive audiometry, physical examination/phlebotomy and completed validated questionnaires. Data relating to germ cell tumor diagnosis and treatment were abstracted from medical records using standardized forms described previously (10). All abstractors participated in centralized, in-person training (10). Study procedures were approved by the Human Subjects Review Board at each institution, with all patients providing written consent. The studies were conducted in accordance with recognized ethical guidelines (U.S. Common Rule).
Identifying Patients with Severe Hearing Loss, Tinnitus, or Peripheral Sensory Neuropathy
Hearing loss was assessed using American Speech-Language-Hearing Association (ASHA) criteria. Audiometry data from 4-12 kHz were included in the analysis, since hearing thresholds at each of these frequencies shows significant dose-response relationships with cumulative cisplatin dose (4), and were previously used in our GWAS of cisplatin-induced hearing loss (5). Patients with moderate (41-55 dB), moderately severe (56-70 dB), severe (71-90 dB), or profound (> 90 dB) hearing loss at frequencies between 4-12 kHz were designated as cases, while patients with no (< 20 dB) or mild (21-40 dB) hearing loss were designated as controls.
Using the Scale for Chemotherapy-Induced Long-Term Neurotoxicity (SCIN) (12), testicular cancer survivors were dichotomized to tinnitus cases/controls as previously described (6) based on responses to the question: “have you had in the last 4 weeks: Ringing or buzzing in the ears?” Cases responded “Quite a bit/very much”, and controls responded “Not at all”. Those answering “A little” were not included to establish a more rigorous phenotype. Testicular cancer survivors were also asked: “Do you have: ringing and buzzing in the ears?” Any tinnitus cases from the previous question that then responded “No” to this question were excluded from analysis.
Peripheral sensory neuropathy was evaluated as previously described (7) using nine items in the validated EORTC-CIPN20 (13). Briefly, an ordinal (0-3) scale was constructed after taking the mean of symptom severity: 0 for “None”, 1 for “A little”, 2 for “Quite a bit”, and 3 for “Very much.” Groups 2 and 3 were combined to denote cases, while those in category 1 were eliminated to establish a more rigorous phenotype.
Establishment of the Multiple Severe Cisplatin-Induced Neurotoxicities Phenotype
Evaluation of tinnitus, audiometrically-defined hearing loss, and peripheral sensory neuropathy revealed that all toxicities were highly associated (Figure 1). Given the association and the biological plausibility, we theorized that one common phenotype may confer a common risk to all three phenotypes. We defined a single case-control phenotype based on the presence or absence of the three toxicities. Subjects who were classified as cases in 2 or 3 of the 3 toxicities constituted the cases of the multiple severe neurotoxicity phenotype. Those who were controls in all three phenotypes constituted the controls. Subjects who were cases in only one of the three phenotypes were excluded from the analysis. Patients with missing responses were also eliminated with demographics described in Supplemental Table 1. Application of the above criteria resulted in 104 cases and 196 controls. Of 104 cases, 38 had all three severe neurotoxicities (Supplemental Table 2).
Figure 1. Relationships Between Cisplatin-Induced Hearing Loss, Tinnitus, and Peripheral Sensory Neuropathy (PSN) in Testicular Cancer Survivors.
Associations between A) hearing loss and tinnitus (p<2x10−16), B) hearing loss and peripheral sensory neuropathy (p=3.94x10−12), and C) peripheral sensory neuropathy and tinnitus (p<2x10−16) are highly significant, forming the basis for combining the most severe forms of all three toxicities into a single phenotype. Statistical significance was assessed through ordinal logistic regression.
Additional Patient-Reported Outcomes and Medical Records Data Abstraction
Patients completed questionnaires ascertaining adverse events, lifestyle habits, comorbidities, and medication use, as previously described (4, 10). Peripheral motor neuropathy was evaluated using a summary score similar to peripheral sensory neuropathy as previously described (7) and Raynaud phenomenon was evaluated using SCIN as previously described (12). For self-reported health, patients were asked the following question: “Would you rate your health as: 1) Excellent; 2) Very good; 3) Good; 4) Fair; 5) Poor?” Responses of “Fair” and “Poor” were combined. Hypogonadism was defined as testosterone levels ≤ 3 ng/mL based on crude measurement or whether the patient was on testosterone therapy. All patients with testosterone levels > 3 ng/mL and were not on testosterone therapy were labeled as normal, and were grouped together as controls for the logistic regression analysis, as previously described (14).
We defined lifestyle habits based on patient responses to the Platinum Study questionnaire, as previously described (7). Briefly, alcohol consumption was assessed as the response to the question “During the past year, how many drinks of alcoholic beverage have you consumed on average? (1 drink = 12 oz. beer [1 can or bottle], 4 oz. glass of wine, 1 mixed drink or shot of liquor)” with the following options: Rarely/never (0), 1-3/month (1), 1/week (2), 2-4/week (3), 5-6/week (4), 1/day (5), 2-3/day (6), 4-5/day (7), and 6+/day (8). Excessive drinking was defined as those who consumed ≥ 2-3 alcoholic drinks per day. Tobacco use was assessed as the response to the following two questions: “Have you ever smoked cigarettes?” and “Do you currently smoke cigarettes?” with “Yes” (1) and “No” (0) options.
In addition to evaluating cumulative cisplatin dose, we examined whether serum platinum levels assessed after treatment completion (measured as residual platinum values) were associated with multiple severe neurotoxicities. Residual platinum values were calculated from a bi-exponential model adjusted for follow-up time and cumulative cisplatin dose, as previously described (15). From these calculated residual platinum values, we ascertained an ordinal version of serum platinum by stratifying values based on their deviation from the mean to create three levels: “medium” (regression residuals=0±1 standard deviation [SD]), “low” (residuals<−1 SD), and “high” (residuals>1 SD).
Phenotype Association Analysis
To investigate important phenotypic correlations between multiple severe cisplatin-induced neurotoxicities and responses from the Platinum Study questionnaire, univariate and multivariable logistic regressions were used to evaluate statistical significance. Where indicated, associations were adjusted for age at clinical examination and cumulative cisplatin dose. Analyses were performed in R 3.3.2, with statistical significance set at p<0.05.
Genotyping and Genome-Wide Analyses
DNA was extracted from peripheral blood at the time of clinical evaluation. Genotyping was performed on the Infinium Global Screening Array-24 chip (GSA-24v1-0_A1; Illumina, San Diego, CA) at Regeneron Pharmaceuticals (Tarrytown, NY). A genome-wide association study (GWAS) of multiple severe cisplatin-induced neurotoxicities was performed in PLINK v1.9 (16, 17) with logistic regression assuming additive effects. Cumulative cisplatin dose, age at clinical examination, and the first 20 genetic principal components (SMARTPCA; (18) were included as covariates. Sample-level QC criteria included: sample call rate>0.99, pairwise identity by descent<0.185, coefficient of inbreeding F<6 standard deviations from the mean, and genetically European as determined by principal components analysis (performed using SMARTPCA). Single nucleotide polymorphism (SNP)-level QC consisted of the following inclusion criteria: call rate>0.99, MAF>0.05, and Hardy-Weinberg equilibrium (HWE) Chi-squared p>1x10−6. Imputation was done on the University of Michigan Imputation Server. SNPs and samples passing QC criteria comprised the input set for imputation with EAGLE phasing using the Haplotype Reference Consortium (19-21). SNPs with imputation R2<0.8, MAF<0.05, HWE p<1x10−6, and INFO scores>1.05 or <0.6 were excluded. Only subjects who passed QC were included in the GWAS (Supplemental Figure 1). Significance was set to p≤5x10−8. The GWAS included 300 subjects with 5,385,324 SNPs. Summary statistics for the GWAS were then uploaded to FUMA (22) to run a gene-based association analysis and for region-based plotting. Inputted SNPs were mapped to 18,404 protein coding genes, producing a significance threshold of p=2.7x10−6. For the gene-based association analysis, the aggregated effect of all SNPs within a gene was analyzed simultaneously in FUMA using MAGMA based on a multiple linear principal components regression (23).
Evaluation of Cisplatin Sensitivity Based on Gene Expression In Silico
Gene expression data in central nervous system (CNS) and other tumor cell lines was obtained from the Cancer Cell Line Encyclopedia (24). Cisplatin sensitivity, measured as the area under the dose-response curve, was obtained from the Genomics of Drug Sensitivity in Cancer Project (25). Spearman correlation and linear regression were performed between normalized expression and sensitivity of cancer cell lines with non-missing expression data in R 3.3.2.
Results
Cohort Characteristics
Demographic and clinical characteristics for testicular cancer survivors included in the GWAS of multiple severe cisplatin-induced neurotoxicities are provided in Table 1 and Supplemental Table 3. Median age at diagnosis for all patients was 28 years (range: 15-54 years), while age at clinical examination was 35 years (range: 18-68 years). Patients were treated with the following regimens: BEP (bleomycin, etoposide, and cisplatin; 53%), EP (etoposide and cisplatin; 38%), VIP (etoposide, ifosfamide, and cisplatin; 1.7%), VeIP (vinblastine, ifosfamide, and cisplatin; 0.3%), and other (unspecified cisplatin-based chemotherapy; 7%). Multiple severe neurotoxicity controls received a median cumulative cisplatin dose of 300 mg/m2 (range: 100-1,000 mg/m2), while cases received a median cumulative cisplatin dose of 400 mg/m2 (range: 100-800 mg/m2).
Table 1.
Clinical and Sociodemographic Characteristics for Testicular Cancer Survivors Based on the Occurrence of Multiple Severe Neurotoxicities.
| Status: Multiple Severe Neurotoxicities | |||
|---|---|---|---|
| Characteristic | All Patients | Controls (No Severe Neurotoxicities) |
Cases (2-3 Severe Neurotoxicities) |
| n | 300 | 196 | 104 |
| Age at Clinical Examination (years) | |||
| Median (range) | 35 (18-68) | 32 (18-58) | 45 (22-68) |
| < 20 | 3 (1.0%) | 3 (1.5%) | 0 (0%) |
| 20-29 | 80 (26.7%) | 73 (37.2%) | 7 (6.7%) |
| 30-39 | 108 (36.0%) | 84 (42.9%) | 24 (23.1%) |
| 40-49 | 67 (22.3%) | 28 (14.2%) | 39 (37.5%) |
| 50-59 | 38 (12.7%) | 8 (4.1%) | 30 (28.8%) |
| ≥ 60 | 4 (1.3%) | 0 (0%) | 4 (3.8%) |
| Treatment Regimen | |||
| BEP | 159 (53.0%) | 110 (56.1%) | 49 (47.1%) |
| EP | 114 (38.0%) | 71 (36.2%) | 43 (41.3%) |
| VIP | 5 (1.7%) | 2 (1.0%) | 3 (2.9%) |
| VeIP | 1 (0.3%) | 1 (0.5%) | 0 (0%) |
| Other (includes cisplatin) | 21 (7.0%) | 12 (6.1%) | 9 (8.7%) |
| Cumulative Cisplatin Dose (mg/m2) | |||
| Median (range) | 400 (100-1,000) | 300 (100-1,000) | 400 (100-800) |
| < 300 | 18 (6.0%) | 14 (7.1%) | 4 (3.8%) |
| 300 | 122 (40.7%) | 92 (47.0%) | 30 (28.8%) |
| > 300 and < 400 | 9 (3.0%) | 5 (2.6%) | 4 (3.8%) |
| 400 | 136 (45.3%) | 80 (40.8%) | 56 (53.8%) |
| > 400 | 15 (5.0%) | 5 (2.6%) | 10 (9.6%) |
| Peripheral Motor Neuropathy | |||
| None | 192 (64.0%) | 167 (85.2%) | 25 (24.0%) |
| A Little | 86 (28.7%) | 29 (14.8%) | 57 (54.8%) |
| Quite a Bit/Very Much | 22 (7.3%) | 0 (0%) | 22 (21.2%) |
| Raynaud Phenomenona | |||
| None | 217 (72.6%) | 172 (87.8%) | 45 (43.7%) |
| A Little | 33 (11.0%) | 16 (8.1%) | 17 (16.5%) |
| Quite a Bit/Very Much | 49 (16.4%) | 8 (4.1%) | 41 (39.8%) |
| Self-Reported Healthb | |||
| Excellent | 55 (18.4%) | 43 (22.1%) | 12 (11.7%) |
| Very Good | 131 (44.0%) | 96 (49.2%) | 35 (34.0%) |
| Good | 91 (30.5%) | 53 (27.2%) | 38 (36.9%) |
| Fair/Poor | 21 (7.0%) | 3 (1.5%) | 18 (17.5%) |
Abbreviations: BEP: bleomycin, etoposide, and cisplatin; EP: etoposide and cisplatin; VIP: etoposide, ifosfamide, and cisplatin; VeIP: vinblastine, ifosfamide, and cisplatin
1 patient did not report Raynaud phenomenon status.
2 patients did not report their overall health.
Associations with Risk Factors and Comorbidities
Both age at diagnosis (OR/10 years=3.2, 95% CI: 2.4-4.5, p<0.0001) and age at clinical examination (OR/10 years=3.9, 95% CI: 2.8-5.5, p<0.0001) were associated with multiple severe cisplatin-induced neurotoxicities (Table 2). Cumulative cisplatin dose was significantly associated with multiple severe neurotoxicities (age-adjusted OR/100 mg/m2=1.9, 95% CI: 1.3-3.0, p=0.003; Figure 2A). Patients who received 400 mg/m2 cisplatin had a notably increased likelihood of developing multiple severe neurotoxicities when compared to patients who received 300 mg/m2 (41.2% vs. 24.6%, p=0.007). Residual platinum values were also associated with multiple severe neurotoxicites (age and dose-adjusted OR=3.0, 95% CI: 1.3-7.7, p = 0.01; Figure 2B). Patients with high residual platinum values had a significantly greater incidence of multiple severe neurotoxicities (58.8%) than those with medium (31.3%) or low (16.7%) serum platinum levels (p=0.02).
Table 2.
Risk of Multiple Severe Neurotoxicities According to Sociodemographic Features, Clinical Characteristics, Lifestyle Factors, Medication Use, and Other Variables.
| Clinical Characteristic | n | OR (95% CI) | p-value | Age and Dose- Adjusted OR (95% CI) |
Age and Dose- Adjusted p-value |
|---|---|---|---|---|---|
| Age at Cancer Diagnosis | 300 | 3.2 (2.4, 4.5) | <0.0001 | N/A | N/A |
| Age at Clinical Examination | 300 | 3.9 (2.8,5.5) | <0.0001 | N/A | N/A |
| Excessive Drinking | 298 | 1.1 (0.5, 2.2) | 0.91 | 1.1 (0.4, 2.8) | 0.82 |
| Ever Smokers | 299 | 2.0 (1.2, 3.4) | 0.006 | 2.8 (1.5, 5.2) | 0.001 |
| Current Smokers | 290 | 2.5 (0.96, 6.8) | 0.06 | 6.0 (1.9, 19.3) | 0.002 |
| Prescription Antihypertensive Medication | 289 | 10.2 (4.5, 26.4) | <0.0001 | 3.4 (1.3, 9.8) | 0.02 |
| Prescription High Cholesterol Medication | 291 | 4.0 (1.9, 8.6) | 0.0003 | 1.1 (0.5, 2.7) | 0.81 |
| Prescription Psychotropic Drugs | 172 | 2.5 (1.1, 5.7) | 0.03 | 2.7 (0.97, 7.6) | 0.06 |
| Persistent Dizziness or Vertigo | 289 | 4.9 (1.6, 18.4) | 0.01 | 6.1 (1.5, 27.1) | 0.01 |
Figure 2. Effects of Cumulative Cisplatin Dose and Residual Platinum Value on Proportion of Patients with Multiple Severe Cisplatin-Induced Neurotoxicities.
The overall proportion of testicular cancer survivors with multiple severe cisplatin-induced neurotoxicities is shown based on A) cumulative cisplatin dose and B) residual platinum value. Cumulative cisplatin dose (age-adjusted OR/100 mg/m2=1.9, 95% CI: 1.3-3.0, p=0.003) and residual platinum values (age and dose-adjusted OR=3.0, 95% CI: 1.3-7.7, p = 0.01) were significantly associated with multiple severe neurotoxicities. Patients who received 400 mg/m2 cisplatin had a notably increased likelihood of developing multiple severe neurotoxicities when compared to patients who received 300 mg/m2 (41.2% vs. 24.6%, p=0.007). Patients with high residual platinum values also had a significantly greater incidence of multiple severe neurotoxicities (58.8%) than those with medium (31.3%) or low (16.7%) serum platinum levels (p=0.02). Statistical significance is based on the two-proportions z-test, and sample sizes for each group are indicated within each panel on the x-axis.
Ever smoking (age and dose-adjusted OR=2.8, 95% CI: 1.5-5.2, p=0.001) and current smoking (age and dose-adjusted OR=6.0, 95% CI: 1.9-19.3, p=0.002) were associated with multiple severe neurotoxicities (Table 2), while excessive drinking was not (age and dose-adjusted OR=1.1, 95% CI: 0.4-2.8, p=0.82). Patients with multiple severe neurotoxicities were also more likely to have been prescribed antihypertensive medication (age and dose-adjusted OR=3.4, 95% CI: 1.3-9.8, p=0.02), while an association with cholesterol medication was not statistically significant (age and dose-adjusted OR=1.1, 95% CI: 0.5-2.7, p=0.81; Table 2).
Patients with multiple severe neurotoxicities were also more likely to experience both Raynaud phenomenon (age and dose-adjusted OR=3.5, 95% CI: 2.4-5.5, p<0.0001; Figure 3A) and report symptoms of peripheral motor neuropathy (age and dose-adjusted OR=14.3, 95% CI: 7.4-29.0, p<0.0001; Figure 3B). Notably, there was a much higher proportion of patients with severe Raynaud phenomenon or peripheral motor neuropathy in cases when compared to controls who had no severe neurotoxicities. The association between multiple severe neurotoxicities and Raynaud phenomenon remained statistically significant after adjusting for cumulative bleomycin dose (bleomycin dose-adjusted OR=3.5, 95% CI: 2.2-5.8, p < 0.0001), and there was no significant association between multiple severe neurotoxicities and cumulative bleomycin dose (p = 0.5).
Figure 3. Distributions of Comorbidities in Testicular Cancer Survivors Based on Multiple Severe Cisplatin-Induced Neurotoxicities.
The overall distribution of A) Raynaud phenomenon, B) peripheral motor neuropathy, and C) self-reported health in testicular cancer survivors based on the occurrence of multiple severe neurotoxicities is provided. Patients with multiple severe neurotoxicities were more likely to experience Raynaud phenomenon (age and dose-adjusted OR=3.5, 95% CI: 2.4-5.5, p<0.0001), report symptoms of peripheral motor neuropathy (age and dose-adjusted OR=14.3, 95% CI: 7.4-29.0, p<0.0001), and report poorer overall health (age and dose-adjusted OR=2.2, 95% CI: 1.5-3.3, p<0.0001). All three comorbidities are divided into different degrees of severity, as indicated in the legend. Patients with multiple severe neurotoxicities reported more severe forms of Raynaud phenomenon (p<0.0001), peripheral motor neuropathy (PMN; p <0.0001), and self-reported health (p<0.0001). Sample sizes for each group are indicated within each panel on the x-axis. Differences between the proportions of toxicity severity observed for cases and controls were evaluated for statistical significance through the Cochran-Armitage-Mantel 1df chi-squared trend test (38).
Persistent dizziness or vertigo was also significantly associated with multiple severe cisplatin-induced neurotoxicities (age and dose-adjusted OR=6.1, 95% CI: 1.5-27.1, p=0.01; Table 2). Cases also reported higher psychotropic drug use that was marginally significant (age and dose-adjusted OR=2.7, 95% CI: 0.97-7.6, p=0.06; Table 2). Self-reported health was significantly poorer in patients with multiple severe neurotoxicities than in controls (age and dose-adjusted OR=2.2, 95% CI: 1.5-3.3, p<0.0001; Figure 3C). Notably, 17.5% of cases reported their overall health as fair/poor compared to only 1.5% of controls.
Genome-Wide Association Study
GWAS of multiple severe cisplatin-induced neurotoxicities identified no genome-wide significant SNPs (Supplemental Table 4; Supplemental Figure 2). Gene-based association analysis identified RGS17 (p=3.9x10−5) and FAM20C (p=5.5x10−5) as near genome-wide significant (significance threshold p=2.7x10−6) (Figure 4). In addition, the normalized expression of FAM20C marginally correlated with cisplatin sensitivity in CNS tumor cell lines in silico (Spearman Rho=0.3, p=0.06; R2=0.04, p=0.2; Figure 4), indicative of a protective function against cisplatin-induced damage. Normalized RGS17 expression was not significantly associated with cisplatin sensitivity in CNS tumor cell lines in silico.
Figure 4. Gene-Based Genome-Wide Association Analysis of Multiple Severe Cisplatin-Induced Neurotoxicities.
Summary statistics for SNP-based GWAS were uploaded to FUMA to run a gene-based association analysis based on a multiple linear principal components regression to determine the aggregated effect of all SNPs within a gene. Inputted SNPs were mapped to 18,404 protein coding genes, producing a significance threshold of p=0.05/18,404 (2.7x10−6). A) Manhattan plot of the gene-based association analysis identified RGS17 (p=3.9x10−5) and FAM20C (p=5.5x10−5) as near genome-wide significant. B) Quantile-Quantile plot of results from the gene-based association analysis. C) Scatter plot of cisplatin sensitivity as a function of normalized FAM20C expression are provided for CNS (ρ=0.29, p=0.06; R2=0.04, p=0.20). Cisplatin sensitivity, measured as the area under the cisplatin dose-response curve, for all CNS tumor cell lines was extracted from CancerRX, and gene expression data were downloaded from the Cancer Cell Line Encyclopedia. Expression data were ranked normalized to fit a normal distribution prior to analysis. Correlation was assessed nonparametrically using the Spearman rank method, as well as by linear regression.
Discussion
The current study evaluated associations between non-genetic and genetic factors with severe neurotoxicities in testicular cancer survivors. Our analyses revealed that older patients at diagnosis and clinical examination were more susceptible to developing multiple severe neurotoxicities consistent with previous studies indicating older adults often experience each toxicity: hearing loss, tinnitus, and neuropathies (26). Although the exact mechanisms of this association have not been explicitly studied, renal clearance typically decreases with age (27), which not only makes cisplatin more difficult to eliminate, but also exacerbates its nephrotoxicity. Therefore, older patients likely have a reduced ability to excrete platinum from the body, increasing their likelihood of developing cisplatin-induced toxicities. Accordingly, high serum platinum levels have been associated with age and reduced kidney function (15) and an increased susceptibility to developing multiple severe neurotoxicities. Further, older adults often experience age-related hearing loss, tinnitus, and neuropathies (26). In addition to age, patients who received cumulative cisplatin doses ≥400 mg/m2 are more likely to develop multiple severe neurotoxicities.
Modifiable lifestyle factors also appeared to influence susceptibility to multiple severe cisplatin-induced neurotoxicities. Smoking was significantly associated with multiple severe neurotoxicities, particularly if patients were current smokers. We previously found no association between smoking and hearing loss (4), and only an association with long-term smoking and tinnitus (6), while peripheral sensory neuropathy was associated with ever smoking and long-term smoking (7). However, our previous studies did not evaluate the association between smoking and severe forms of the toxicities, particularly multiple severe toxicities. Hypertension has previously been associated with cisplatin-induced hearing loss (4), tinnitus (6), and peripheral sensory neuropathy in testicular cancer survivors (7), and our analysis showing an association with multiple severe neurotoxicities is in accord with these data.
Testicular cancer survivors with multiple severe cisplatin-induced neurotoxicities were also more likely to report numerous comorbidities. The association between multiple severe neurotoxicities and persistent dizziness or vertigo is in accord with previous studies that indicate both hearing loss and tinnitus are associated with this disorder (28, 29), and can likely be attributed to the intimate relationship between the auditory and vestibular systems of the inner ear. There was also a highly significant association between multiple severe neurotoxicities and Raynaud phenomenon which remained statistically significant after adjusting for cumulative bleomycin dose, a drug known to induce this adverse event (30, 31). The purported association between multiple severe neurotoxicities and reported symptoms consistent with a peripheral motor neuropathy is particularly intriguing because cisplatin typically only induces peripheral sensory neuropathy (32). It is likely that these patients have sensory neuropathy so severe that it perturbs motor functions, subsequently influencing responses to motor neuropathy-specific questions such as problems holding a pen, difficulty manipulating small objects with their fingers, etc. In support of this notion, controls without severe sensory neuropathy had no symptoms of moderate to severe motor neuropathy. These data suggest that the neurotoxicity of cisplatin is highly potent in certain individuals, markedly increasing their likelihood of developing numerous neuro-otological symptoms that affect quality of life. As expected, individuals with multiple severe neurotoxicities reported higher use of antidepressants and poorer overall health. Therefore, this cohort is ideally suited to evaluate modifiable risk factors and genetic variants in an effort to advise patients, and for potential drug development to prevent severe toxicities.
Gene-based association analysis of multiple severe cisplatin-induced neurotoxicities identified FAM20C as near genome-wide significant (p=5.5x10−5), which was also correlated with cisplatin sensitivity in CNS tumor cell lines in silico. FAM20C encodes for a secreted protein kinase that binds calcium and phosphorylates proteins involved in bone mineralization (33, 34). It has been recently demonstrated that high levels of platinum are stored in long bones (35), which can be slowly released over time due to its binding interaction with collagen (36). We have previously estimated that serum platinum levels remain elevated in cisplatin-treated testicular cancer survivors for an excess of 30 years, and are associated with multiple cisplatin-induced toxicities, including kidney damage, tinnitus, and Raynaud phenomenon (15). Consequently, the genetic architecture of bone modeling may play a significant role in platinum retention, which ultimately increases susceptibility to persistent toxicities. Further, the observation that FAM20C expression is inversely correlated with cisplatin sensitivity in CNS cancer cell lines suggests that the gene exerts a protective effect in tissues relevant to neurotoxicity. If lower FAM20C expression influences the ability of bone to release platinum into circulation, elevated platinum levels would likely persist in long-term survivors, potentiating the neurotoxicity of cisplatin.
Major strengths of our study include the comprehensiveness of the Platinum Study questionnaire and clinical evaluation (including audiometry) that enabled us to evaluate whether patients had multiple severe neurotoxicities following cisplatin-based chemotherapy. Our study marks the first evaluation of non-genetic and genetic risk factors contributing to multiple severe cisplatin-induced neurotoxicities, and provides a framework by which to examine other antineoplastic agents that elicit multiple persistent adverse reactions. An inherent limitation of our study is the small sample size used to evaluate genetic predisposition to multiple severe neurotoxicities (cases: 104; controls: 196) as a consequence of our strict criteria used to define cases and controls, which may have not been sufficiently powered to identify individual genetic variants. However, we were able to increase the overall power of our genetic analysis by examining the aggregated effect of SNPs in an individual gene for their association with the phenotype, and identified FAM20C as near genome-wide significant. Further, FAM20C expression was inversely associated with cisplatin sensitivity in silico. Therefore, the incorporation of gene-based analyses in pharmacogenomic studies can be highly advantageous, particularly when using a relatively small patient cohort.
Our study demonstrates the utility of examining patients with severe hearing loss, tinnitus, and/or peripheral sensory neuropathy following cisplatin-based chemotherapy, three of the most common and persistent toxicities experienced by testicular cancer survivors. Individuals who do develop multiple severe neurotoxicities are likely to experience concurrent dizziness or vertigo, Raynaud Phenomenon, and/or symptoms of peripheral motor neuropathy. Accordingly, these patients report higher use of antidepressants, and have a poorer quality of life when compared to patients who do not develop multiple severe neurotoxicities. In view of our results, health care providers can improve management of cancer survivors by informing patients of their risk to multiple severe cisplatin-induced neurotoxicities and associated comorbidities that may persist years after completion of therapy, particularly older patients, and those who received cumulative doses of cisplatin equivalent to or exceeding 400 mg/m2, have a history of smoking, and are taking antihypertensive medication. Thus, we would recommend BEP x 3 rather than EP x 4 for good risk disease which limits the cisplatin dosage to 300mg/m2. We tend to avoid bleomycin for patients over age 50. However if the EP regimen is chosen, optimal cure requires 4 courses of EP (400 mg/m2 cisplatin) as a prior Eastern Cooperative Group study randomized good risk patients to BEP x 3 versus EP x 3, and there was a statistically significant reduction in the cure rate with just EP x 3 (37). In addition, our GWAS identified FAM20C to be associated with multiple severe cisplatin-induced neurotoxicities, which warrants further examination to identify how perturbation of its function or expression can potentiate cisplatin-induced neurotoxicity.
Supplementary Material
Translational Relevance.
Cisplatin has been used to treat testicular cancer for over 40 years. However, it remains difficult to predict which patients will develop severe, persistent neurotoxicities in the form of hearing loss, tinnitus, and/or peripheral sensory neuropathy. Since patients diagnosed with testicular cancer are typically young adults, individuals who do develop persistent neurotoxicities endure long-term consequences ultimately reducing quality of life and productivity. In this study, we characterize the incidence of multiple severe cisplatin-induced neurotoxicities in testicular cancer survivors to identify non-genetic and genetic risk factors. We find that certain individuals have markedly increased risk of developing numerous neuro-otological symptoms. In view of our results, health care providers can improve management of survivors by informing patients of their risk to develop multiple severe neurotoxicities and associated comorbidities that may persist years after completion of therapy.
Acknowledgements.
This work was supported by the National Institutes of Health Genetic Susceptibility and Biomarkers of Platinum-related Toxicities grant (R01 CA157823, LB Travis), NIH/NCI Cancer Center Support Grant P30 CA008748 (DR Feldman) and the University of Chicago Comprehensive Cancer Center Women’s Board (ME Dolan). The authors would like to thank the Regeneron Genetics Center who performed DNA sample genotyping and provided insight regarding the interpretation of the results from the genetic analyses.
Footnotes
Conflict of Interest: Darren R. Feldman has a relationship with Decibel and UpToDate. All other authors declare no conflicts of interest.
References
- 1.Siegel RL, Miller KD, Jemal A. Cancer statistics, 2018. CA Cancer J Clin. 2018;68:7–30. [DOI] [PubMed] [Google Scholar]
- 2.Fung C, Sesso HD, Williams AM, Kerns SL, Monahan P, Abu Zaid M, et al. Multi-Institutional Assessment of Adverse Health Outcomes Among North American Testicular Cancer Survivors After Modern Cisplatin-Based Chemotherapy. J Clin Oncol. 2017;35:1211–22. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Chovanec M, Abu Zaid M, Hanna N, El-Kouri N, Einhorn LH, Albany C. Long-term toxicity of cisplatin in germ-cell tumor survivors. Ann Oncol. 2017;28:2670–9. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Frisina RD, Wheeler HE, Fossa SD, Kerns SL, Fung C, Sesso HD, et al. Comprehensive Audiometric Analysis of Hearing Impairment and Tinnitus After Cisplatin-Based Chemotherapy in Survivors of Adult-Onset Cancer. J Clin Oncol. 2016;34:2712–20. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Wheeler HE, Gamazon ER, Frisina RD, Perez-Cervantes C, El Charif O, Mapes B, et al. Variants in WFS1 and Other Mendelian Deafness Genes Are Associated with Cisplatin-Associated Ototoxicity. Clin Cancer Res. 2017;23:3325–33. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.El Charif O, Mapes B, Trendowski MR, Wheeler HE, Wing C, Dinh PC Jr., et al. Clinical and Genome-wide Analysis of Cisplatin-induced Tinnitus Implicates Novel Ototoxic Mechanisms. Clin Cancer Res. 2019;25:4104–16. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7.Dolan ME, El Charif O, Wheeler HE, Gamazon ER, Ardeshir-Rouhani-Fard S, Monahan P, et al. Clinical and Genome-Wide Analysis of Cisplatin-Induced Peripheral Neuropathy in Survivors of Adult-Onset Cancer. Clin Cancer Res. 2017;23:5757–68. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8.Weidt S, Delsignore A, Meyer M, Rufer M, Peter N, Drabe N, et al. Which tinnitus-related characteristics affect current health-related quality of life and depression? A cross-sectional cohort study. Psychiatry Res. 2016;237:114–21. [DOI] [PubMed] [Google Scholar]
- 9.Lawrence BJ, Jayakody DMP, Bennett RJ, Eikelboom RH, Gasson N, Friedland PL. Hearing Loss and Depression in Older Adults: A Systematic Review and Meta-analysis. Gerontologist. 2020;60:e137–e54. [DOI] [PubMed] [Google Scholar]
- 10.Kerns SL, Fung C, Monahan PO, Ardeshir-Rouhani-Fard S, Abu Zaid MI, Williams AM, et al. Cumulative Burden of Morbidity Among Testicular Cancer Survivors After Standard Cisplatin-Based Chemotherapy: A Multi-Institutional Study. J Clin Oncol. 2018;36:1505–12. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Travis LB, Fossa SD, Sesso HD, Frisina RD, Herrmann DN, Beard CJ, et al. Chemotherapy-induced peripheral neurotoxicity and ototoxicity: new paradigms for translational genomics. J Natl Cancer Inst. 2014;106. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12.Oldenburg J, Fossa SD, Dahl AA. Scale for chemotherapy-induced long-term neurotoxicity (SCIN): psychometrics, validation, and findings in a large sample of testicular cancer survivors. Qual Life Res. 2006;15:791–800. [DOI] [PubMed] [Google Scholar]
- 13.Postma TJ, Aaronson NK, Heimans JJ, Muller MJ, Hildebrand JG, Delattre JY, et al. The development of an EORTC quality of life questionnaire to assess chemotherapy-induced peripheral neuropathy: the QLQ-CIPN20. Eur J Cancer. 2005;41:1135–9. [DOI] [PubMed] [Google Scholar]
- 14.Zaid MA, Gathirua-Mwangi WG, Fung C, Monahan PO, El-Charif O, Williams AM, et al. Clinical and Genetic Risk Factors for Adverse Metabolic Outcomes in North American Testicular Cancer Survivors. J Natl Compr Canc Netw. 2018;16:257–65. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 15.Trendowski MR, El-Charif O, Ratain MJ, Monahan P, Mu Z, Wheeler HE, et al. Clinical and Genome-Wide Analysis of Serum Platinum Levels after Cisplatin-Based Chemotherapy. Clin Cancer Res. 2019;25:5913–24. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Purcell S, Neale B, Todd-Brown K, Thomas L, Ferreira MA, Bender D, et al. PLINK: a tool set for whole-genome association and population-based linkage analyses. Am J Hum Genet. 2007;81:559–75. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17.Chang CC, Chow CC, Tellier LC, Vattikuti S, Purcell SM, Lee JJ. Second-generation PLINK: rising to the challenge of larger and richer datasets. Gigascience. 2015;4:7. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 18.Anderson CA, Pettersson FH, Clarke GM, Cardon LR, Morris AP, Zondervan KT. Data quality control in genetic case-control association studies. Nat Protoc. 2010;5:1564–73. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 19.Das S, Forer L, Schonherr S, Sidore C, Locke AE, Kwong A, et al. Next-generation genotype imputation service and methods. Nat Genet. 2016;48:1284–7. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 20.Loh PR, Danecek P, Palamara PF, Fuchsberger C, Y AR, H KF, et al. Reference-based phasing using the Haplotype Reference Consortium panel. Nat Genet. 2016;48:1443–8. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 21.McCarthy S, Das S, Kretzschmar W, Delaneau O, Wood AR, Teumer A, et al. A reference panel of 64,976 haplotypes for genotype imputation. Nat Genet. 2016;48:1279–83. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 22.Watanabe K, Taskesen E, van Bochoven A, Posthuma D. Functional mapping and annotation of genetic associations with FUMA. Nat Commun. 2017;8:1826. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 23.de Leeuw CA, Mooij JM, Heskes T, Posthuma D. MAGMA: generalized gene-set analysis of GWAS data. PLoS Comput Biol. 2015;11:e1004219. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 24.Barretina J, Caponigro G, Stransky N, Venkatesan K, Margolin AA, Kim S, et al. The Cancer Cell Line Encyclopedia enables predictive modelling of anticancer drug sensitivity. Nature. 2012;483:603–7. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 25.Yang W, Soares J, Greninger P, Edelman EJ, Lightfoot H, Forbes S, et al. Genomics of Drug Sensitivity in Cancer (GDSC): a resource for therapeutic biomarker discovery in cancer cells. Nucleic Acids Res. 2013;41:D955–61. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 26.Trendowski MR, El Charif O, Dinh PC Jr., Travis LB, Dolan ME. Genetic and Modifiable Risk Factors Contributing to Cisplatin-induced Toxicities. Clin Cancer Res. 2019;25:1147–55. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 27.Mangoni AA, Jackson SH. Age-related changes in pharmacokinetics and pharmacodynamics: basic principles and practical applications. Br J Clin Pharmacol. 2004;57:6–14. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 28.Newman-Toker DE, Della Santina CC, Blitz AM. Vertigo and hearing loss. Handb Clin Neurol. 2016;136:905–21. [DOI] [PubMed] [Google Scholar]
- 29.Miura M, Goto F, Inagaki Y, Nomura Y, Oshima T, Sugaya N. The Effect of Comorbidity between Tinnitus and Dizziness on Perceived Handicap, Psychological Distress, and Quality of Life. Front Neurol. 2017;8:722. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 30.Vogelzang NJ, Bosl GJ, Johnson K, Kennedy BJ. Raynaud’s phenomenon: a common toxicity after combination chemotherapy for testicular cancer. Ann Intern Med. 1981;95:288–92. [DOI] [PubMed] [Google Scholar]
- 31.McGrath SE, Webb A, Walker-Bone K. Bleomycin-induced Raynaud’s phenomenon after single-dose exposure: risk factors and treatment with intravenous iloprost infusion. J Clin Oncol. 2013;31:e51–2. [DOI] [PubMed] [Google Scholar]
- 32.Staff NP, Grisold A, Grisold W, Windebank AJ. Chemotherapy-induced peripheral neuropathy: A current review. Ann Neurol. 2017;81:772–81. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 33.Tagliabracci VS, Wiley SE, Guo X, Kinch LN, Durrant E, Wen J, et al. A Single Kinase Generates the Majority of the Secreted Phosphoproteome. Cell. 2015;161:1619–32. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 34.Liu C, Zhang H, Jani P, Wang X, Lu Y, Li N, et al. FAM20C regulates osteoblast behaviors and intracellular signaling pathways in a cell-autonomous manner. J Cell Physiol. 2018;233:3476–86. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 35.Breglio AM, Rusheen AE, Shide ED, Fernandez KA, Spielbauer KK, McLachlin KM, et al. Cisplatin is retained in the cochlea indefinitely following chemotherapy. Nat Commun. 2017;8:1654. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 36.Chang Q, Ornatsky OI, Siddiqui I, Straus R, Baranov VI, Hedley DW. Biodistribution of cisplatin revealed by imaging mass cytometry identifies extensive collagen binding in tumor and normal tissues. Sci Rep. 2016;6:36641. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 37.Loehrer PJ Sr., Johnson D, Elson P, Einhorn LH, Trump D. Importance of bleomycin in favorable-prognosis disseminated germ cell tumors: an Eastern Cooperative Oncology Group trial. J Clin Oncol. 1995;13:470–6. [DOI] [PubMed] [Google Scholar]
- 38.N. M Chi-square tests with one degree of freedom: extensions of the Mantel–Haenszel procedure. Journal of the American Statistical Association. 1963;28:690–700. [Google Scholar]
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