Comparative overall survival of CDK4/6 inhibitors in combination with endocrine therapy in advanced breast cancer.

Individual trials of abemaciclib, palbociclib, and ribociclib show a similar impact on progression-free survival yet differing statistical significance for overall survival (OS). A robust comparative evaluation of OS, safety, and tolerability of the three drugs is warranted. A systematic literature search identified phase 3 randomized clinical trials reporting OS of CDK4/6 inhibitors (CDK4/6i) in combination with endocrine therapy in ER-positive/HER2-negative advanced breast cancer. Trial-level data on OS and common and serious adverse events (AE) were extracted for each drug. In the absence of direct comparisons, a network meta-analysis was performed to evaluate pairwise comparative efficacy, safety, and tolerability of each of the CDK4/6i. Seven studies comprising of 4415 patients met the inclusion criteria. Median follow-up was 73.3 months (range: 48.7-97.2 months). There were no statistically significant differences in OS between any of the CDK4/6i. Compared to palbociclib, ribociclib and abemaciclib both showed significantly higher GI toxicity (grade 1-2 vomiting OR 1.87 [95% CI 1.37-2.56] and OR 2.27 [95% CI 1.59-3.23] respectively). Compared to palbociclib, abemaciclib was associated with more grade 3-4 diarrhea OR 118.06 [95% CI 7.28-1915.32]. In contrast, palbociclib was associated with significantly more neutropenia than ribociclib and abemaciclib but significantly lower risk of grade 3-4 infections. Abemaciclib had significantly less grade 3-4 transaminitis and grade 3-4 neutropenia than ribociclib. Treatment discontinuation and death due to AE were significantly higher with abemaciclib than palbociclib and ribociclib. There is no statistically significant difference in OS between CDK4/6i despite differing statistical significance levels of individual trials. Real-world data analyses may help to identify if there is a meaningful inter-drug difference in efficacy. Significant differences between CDK4/6i are observed for safety and tolerability outcomes.

Magnitude of effect and sample size justification in trials supporting anti-cancer drug approval by the US Food and Drug Administration.

Approval of drugs is based on randomized trials observing statistically significant superiority of an experimental agent over a standard. Statistical significance results from a combination of effect size and sampling, with larger effect size more likely to translate to population effectiveness. We assess sample size justification in trials supporting cancer drug approvals. We identified US FDA anti-cancer drug approvals for solid tumors from 2015 to 2019. We extracted data on study characteristics, statistical plan, accrual, and outcomes. Observed power (Pobs) was calculated based on completed study characteristics and observed hazard ratio (HRobs). Studies were considered over-sampled if Pobs > expected with HRobs similar or worse than expected or if Pobs was similar to expected with HRobs worse than expected. We explored associations with over-sampling using logistic regression. Of 75 drug approvals (reporting 94 endpoints), 21% (20/94) were over-sampled. Over-sampling was associated with immunotherapy (OR: 5.5; p = 0.04) and associated quantitatively but not statistically with targeted therapy (OR: 3.0), open-label trials (OR: 2.5), and melanoma (OR: 4.6) and lung cancer (OR: 2.17) relative to breast cancer. Most cancer drug approvals are supported by trials with justified sample sizes. Approximately 1 in 5 endpoints are over-sampled; benefit observed may not translate to clinically meaningful real-world outcomes.

Meta-analysis of sex and racial subgroup participation rates and differential treatment effects for trials in solid tumor malignancies leading to US Food and Drug Administration registration between 2010 and 2021.

BACKGROUND: The lack of sociodemographic diversity in clinical trials limits the generalizability of results. The authors examined participation rates and effect modification by sex and race in oncology trials. METHODS: The authors extracted outcome data stratified by sex and race for registration trials supporting US Food and Drug Administration (FDA) approval (2010-2021). Effect modification by race and sex was examined using quantitative and qualitative methods. A random-effects meta-analysis and pairwise comparison of progression-free survival (PFS) and overall survival (OS) outcomes was conducted by sex and race. RESULTS: Ninety-five trials with 123 end points and 54,365 patients provided information on sex. Trial patients were more often male (n = 35,482; 65% vs. 56% male patients in US Surveillance, Epidemiology, and End Results [SEER] data), although the proportion of male patients was similar after adjusting by tumor type (60% in FDA data vs. 58% in SEER data). There was no difference in pooled outcomes among male versus female patients (PFS: hazard ratio, 0.99; 95% confidence interval, 0.92-1.07; p = .89; OS: hazard ratio, 0.99; 95% confidence interval, 0.93-1.07; p = .90). In total, 111 trials including 74,217 patients provided information on race, and 68% of patients identified as White, compared with 72.3% in US SEER incidence data. Black patients were under-represented compared with US SEER incidence data, although ethnicity was poorly reported throughout the data set. In the authors' network meta-analysis by race, there were no statistically significant differences in PFS or OS outcomes. CONCLUSIONS: No significant differences in PFS or OS outcomes were identified when the analyses were stratified by sex or race. Certain racial minorities remain under-represented, and clearer reporting of race and ethnicity is needed. Representation of female patients in FDA trials is similar to that in SEER data after adjusting for tumor type.

Differential treatment effect between younger and older adults for new cancer therapies in solid tumors supporting US Food and Drug Administration approval between 2010 and 2021.

BACKGROUND: Over one half of cancer diagnoses occur in patients aged 65 and older. The authors quantified how treatment effects differ between older and younger patients in oncology registration trials. METHODS: The authors performed a retrospective cohort study of registration trials supporting US Food and Drug Administration approval of cancer drugs (from January 2010 to December 2021). The primary outcome was differential treatment effect by age (younger than 65 years vs. 65 years or older) for progression-free survival and overall survival. Random effects meta-analysis and a pairwise comparison of outcomes by age group also were performed. RESULTS: Among 263 trials that met the inclusion criteria, 120 trials with 153 end points and 83,152 patients presented age-specific outcome data. Among the included randomized patients, 38% were aged 65 years and older compared with an incidence proportion of 55% in data from the National Cancer Institute's Surveillance, Epidemiology, and End Results program. Studies evaluating prostate cancer had the highest representation of patients aged 65 years or older (73%), whereas breast cancer studies had the lowest (20%). There were no changes in the proportion of patients aged 65 years or older over time (p = .86). Only 7% of end points showed a statistically significant interaction between outcome and age group. In a pooled analysis, there was an association between treatment effect and age for progression-free survival that approached but did not meet significance (hazard ratio, 0.95; p = .06), and there was no difference for overall survival (hazard ratio, 0.97; p = .79). CONCLUSIONS: Older adults remain under-represented in oncology registration trials. Significant differences in outcomes by age group were uncommon in individual trials and pooled analyses. However, clinical trial participants differ from real-world patients older than 65 years, and increased enrollment and ongoing research into differential treatment effects by age are needed.

Management of Oligometastatic Breast Cancer: An Expert Committee's Opinion.

Patients with oligometastatic breast cancer (BC) are candidates of choice for metastasis-directed therapy (MDT). This paper summarizes the opinions of an expert committee about the management of oligometastatic BC. The experts could complete the questionnaire from 13 September 2021, to 10 October 2021, followed by a discussion. The experts were physicians working in the Province of Quebec (Canada) and specialized in BC care, including surgical oncologists, medical oncologists, and radiation oncologists. The experts provided their opinions about the context of the disease and therapeutic approach, local and systemic therapies, and the prognosis of oligometastatic BC. In addition to the expert panel's opinions about the management of oligometastatic disease per se, the experts stated that a prospective data registry should be implemented to collect data about oligometastatic BC to improve knowledge about oligometastatic BC and implement data-driven MDT. These data could also allow for the design of treatment algorithms. In conclusion, this paper presents the expert panel's opinions about the management of oligometastatic BC and highlights the needs to be met to improve the care of this condition.

Perceived guideline clarity impacts guideline-concordant care for breast cancer screening in women age 40-49.

BACKGROUND: Canadian and US Task Forces recommend against routine mammography screening for women age 40-49 at average breast cancer risk as harms outweigh benefits. Both suggest individualized decisions based on the relative value women place on potential screening benefits and harms. Population-based data reveal variation in primary care professionals (PCPs) mammography rates in this age group after adjusting for sociodemographic factors, highlighting the need to explore PCP screening perspectives and how this informs clinical behaviours. Results from this study will inform interventions that can improve guideline concordant breast screening for this age group. METHODS: Qualitative semi-structured interviews were performed with PCPs in Ontario, Canada. Interviews were structured using the theoretical domains framework (TDF) to explore determinants of breast cancer screening best-practice behaviours: (1) risk assessment; (2) discussion regarding benefits and harms; and (3) referral for screening. ANALYSIS: Interviews were transcribed and analyzed iteratively until saturation. Transcripts were coded deductively by behaviour and TDF domain. Data that did not fit within a TDF code were coded inductively. The research team met repeatedly to identify potential themes that influenced or were important consequences of the screening behaviours. The themes were tested against further data, disconfirming cases, and different PCP demographics. RESULTS: Eighteen physicians were interviewed. The theme of perceived guideline clarity (a lack of clarity on guideline-concordant practices) influenced all behaviours and moderated the extent to which the risk assessment and discussion occurred. Many were unaware of how risk-assessment factored into the guidelines and/or did not perceive that a shared-care discussion was guideline-concordant. Deferral to patient preference (screening referral without a complete discussion of benefits and harms) occurred when the PCPs had low knowledge regarding harms and/or if they experienced regret (TDF domain: emotion) resulting from prior clinical experiences. Older providers described patient's influence impacting their decisions and physicians trained outside Canada, practicing in higher-resourced areas, and female physicians described being influenced by beliefs about consequences of benefits of screening. CONCLUSION: Perceived guideline clarity is an important driver of physician behaviour. Improving guideline concordant care should start by clarifying the guideline itself. Thereafter, targeted strategies include building skills in identifying and overcoming emotional factors and communication skills important for evidence-based screening discussions.

Determinants of guideline-concordant breast cancer screening by family physicians for women aged 40-49 years: a qualitative analysis.

BACKGROUND: Although the current Canadian Task Force on Preventive Health Care guideline recommends that physicians should inform women aged 40-49 years of the potential benefits and harms of screening mammography to support individualized decisions, previous reports of variation in clinical practice at the physician level suggest a lack of guideline-concordant care. We explored determinants (barriers and facilitators) of guideline-concordant care by family physicians regarding screening mammography in this age group. METHODS: We conducted qualitative semi-structured interviews by phone with family physicians in the Greater Toronto Area from January to November 2020. We structured interviews using the Theoretical Domains Framework to explore determinants (barriers and facilitators) of 5 physician screening behaviours, namely risk assessment, discussion regarding benefits and harms, decision or referral for mammography, referral for genetic counselling and referral to high-risk screening programs. Two independent researchers iteratively analyzed interview transcripts and deductively coded for each behaviour by domain to identify key behavioural determinants until saturation was reached. RESULTS: We interviewed 18 physicians (mean age 48 yr, 72% self-identified as women). Risk assessment was influenced by physicians' knowledge of risk factors, skills to synthesize risk and beliefs about utility. Physicians had beliefs in their capabilities to have informed patient-centred discussions, but insufficient knowledge regarding the harms of screening. The decision or referral for mammography was affected by emotions related to past patient outcomes, social influences of patients and radiology departments, and knowledge and beliefs about consequences (benefits and harms of screening). Referrals for genetic counselling and to high-risk screening programs were facilitated by their availability and by the knowledge and skills to complete forms. Lack of knowledge regarding which patients qualify and beliefs about consequences were barriers to referral. INTERPRETATION: Insufficient knowledge and skills for performance of risk assessment, combined with a tendency to overestimate benefits of screening relative to harms affected provision of guideline-concordant care. These may be effective targets for future interventions to improve guideline-concordant care.

A retrospective analysis of changes in distant and breast cancer related disease-free survival events in adjuvant breast cancer trials over time.

Disease-free survival (DFS) comprises both breast cancer and non-breast cancer events. DFS has not been validated as a surrogate endpoint for overall survival (OS) in most breast cancer subtypes. We assessed changes to the type of events contributing to DFS over time. We identified adjuvant studies in breast cancer (BC) from 2000 to 2020 where the endpoint was DFS. We examined change in distant DFS events and the BC-related DFS using univariable and multivariable linear regression. Data were reported quantitatively using the Burnand criteria irrespective of statistical significance. We included 84 studies (88 cohorts), comprising 212,191 participants, 41,604 DFS events and 23,205 distant DFS events. The DFS event rate/100 participants/year has declined modestly over time (ß - 0.34, p = 0.001). Start year was negatively associated with distant DFS events (ß - 0.58, p < 0.0001); however, the effect was lost after adjusting for follow-up time (ß - 0.18, p = 0.096). The average number of BC-related events/100 participants/year also declined over time (ß - 0.28, p = 0.009). In multivariable analysis, start year and ER expression were quantitatively associated with distant DFS events and BC-related DFS events. DFS events have declined over time driven by a reduction in BC related events. As DFS events are increasingly defined by non-BC events, there will be limited surrogacy between DFS and OS.

Quantifying Withdrawal of Consent, Loss to Follow-Up, Early Drug Discontinuation, and Censoring in Oncology Trials.

BACKGROUND: Censoring due to early drug discontinuation (EDD) or withdrawal of consent or loss to follow-up (WCLFU) can result in postrandomization bias. In oncology, censoring rules vary with no defined standards. In this study, we sought to describe the planned handling and transparency of censoring data in oncology trials supporting FDA approval and to compare EDD and WCLFU in experimental and control arms. METHODS: We searched FDA archives to identify solid tumor drug approvals and their associated trials between 2015 and 2019, and extracted the planned handling and reporting of censored data. We compared the proportion of WCLFU and EDD between the experimental and control arms by using generalized estimating equations, and performed logistic regression to identify trial characteristics associated with WCLFU occurring more frequently in the control group. RESULTS: Censoring rules were defined adequately in 48 (59%) of 81 included studies. Only 14 (17%) reported proportions of censored participants clearly. The proportion of WCLFU was higher in the control group than in the experimental group (mean, 3.9% vs 2.5%; ß-coefficient, -2.2; 95% CI, -3.1 to -1.3; P<.001). EDD was numerically higher in the experimental arm in 61% of studies, but there was no statistically significant difference in the proportion of EDD between the experimental and control groups (mean, 21.6% vs 19.9%, respectively; ß-coefficient, 0.27; 95% CI, -0.32 to 0.87; P=.37). The proportion of EDD due to adverse effects (AEs) was higher in the experimental group (mean, 13.2% vs 8.5%; ß-coefficient, 1.5; 95% CI, 0.57-2.45; P=.002). WCLFU was higher in the control group in studies with an active control group (odds ratio [OR], 10.1; P<.001) and in open label studies (OR, 3.00; P=.08). CONCLUSIONS: There are significant differences in WCLFU and EDD for AEs between the experimental and control arms in oncology trials. This may introduce postrandomization bias. Trials should improve the reporting and handling of censored data so that clinicians and patients are fully informed regarding the expected benefits of a treatment.

Platinum-based chemotherapy in early-stage triple negative breast cancer: A meta-analysis.

PURPOSE: The addition of platinum agents to anthracycline and taxane-based chemotherapy in early-stage triple negative breast cancer (TNBC) patients improves pathological complete response (pCR). Long-term outcomes, such as disease-free survival (DFS) and overall survival (OS), have not been well-established. METHODS: A systematic literature review identified studies using platinum-based treatment in TNBC patients in the neoadjuvant or adjuvant setting with reportable long-term outcomes. Hazard ratios (HR) from collected data were pooled in a meta-analysis using generic inverse-variance and random effects modeling. Subgroup analyses were conducted based on treatment setting and study design. RESULTS: Fourteen studies comprising 3518 patients met the inclusion criteria. Median follow up was 56.2 months. All studies reported DFS and 9 studies (64%) reported OS. DFS was significantly better in platinum-based treatment (HR 0.71, 95% confidence interval (CI) 0.56-0.89; p = 0.03). However, OS was no different (HR 0.98, 95% CI 0.75-1.27; p = 0.87). There was a non-significant difference between platinum exposure in the adjuvant compared to neoadjuvant setting for both DFS (HR 0.75 vs 0.62, p = 0.43) and for OS (HR 0.90 vs 1.10, p = 0.58). The addition of platinum was associated with more thrombocytopenia and all-grade neuropathy and non-significant increases in neutropenia and grade 3-4 neuropathy. CONCLUSIONS: Platinum-based treatment improves DFS but not OS. The reporting of toxicity was suboptimal, but in general adding platinum increased toxicity. The discordant effect of platinum-based treatment on DFS and OS suggest the potential development of platinum resistance and worse outcomes after recurrence. Platinum-based chemotherapy cannot be recommended in unselected patients with early TNBC.

Patient and provider determinants of breast cancer screening among Ontario women aged 40-49: a population-based retrospective cohort study.

PURPOSE: Canadian breast cancer screening guidelines state that mammography screening for women 40-49 should be individualized based on risk assessment and preferences. This retrospective cohort study describes the frequency of screening in women aged 40-49 and identifies patient and provider-level associations with screening. METHODS: Administrative databases were linked. The overall cohort included Ontario women aged 40-49 between April 1, 2009 and March 31, 2019. Subgroups were created: the "screen" group included women who received a mammogram defined as screening (using a set of exclusion criteria) and the "routine screen" group included women with three or more screening mammograms. A multivariable multilevel logistic regression model accounting for patient and provider characteristics was fit to determine characteristics associated with routine screening. The intracluster correlation co-efficient was used to quantify the degree of variation across providers. RESULTS: Of approximately 2 million eligible women, there were 532,596 (25.5%) in the screen group and 90,651 (4.3%) the routine screen group. There was an average of 0.30 and 0.52 screening mammograms per woman year, in the screen and routine screen groups, respectively. Routine screening was associated with periodic health exams (OR 1.21, 95% CI 1.20-1.22), receiving pap smears (OR 1.38, 95% CI 1.37-1.39), and fee-for-service models of care (OR 1.32, 95% CI 1.27-1.36). Over 20% of the variation in screening was due to systematic between-provider differences. CONCLUSIONS: Approximately 4.3% of women aged 40-49 in Ontario received routine breast cancer screening with substantial variation across providers. Routine screening is associated with periodic health examinations, receipt of pap smears, and fee-for-service models of care.

Fragility of randomized trials supporting cancer drug approvals stratified by approval pathway and review designations.

BACKGROUND: It has been suggested that the results from fragile trials are less likely to translate into benefit in routine clinical practice. METHODS: We searched the Food and Drug Administration (FDA) archives to identify drug approvals for solid organ malignancies between 2010 and 2019. We calculated the Fragility Index (FI) supporting each approval, using methods to account for time-to-event. We compared FI and trial and approval characteristics using Mann-Whitney U and Kruskal-Wallis test. Using logistic regression, we examined study characteristics associated with withdrawal of consent or lost to follow-up (WCLFU) exceeding the calculated FI. RESULTS: The median FI among 125 included studies was 23 (range 1-322). The FI was ≤10 in 35 studies (28%), 11-20 in 21 (17%), and >20 in 69 (55%). The median FI/Nexp was 7.7% (range 0.1-51.7%). The median FI was significantly lower among approvals processed through the accelerated vs regular pathway (5.5 vs 25, p = 0.001), but there was no difference in median FI/Nexp. The WCLFU exceeded FI in 42% of studies. Overall survival endpoints were more likely to have a WCLFU exceeding FI (OR 3.16, p = 0.003). WCLFU exceeding FI was also associated with a lesser magnitude of effect (median HR 0.69 vs 0.55, p < 0.001). In a sensitivity analysis including only studies with 1:1 randomization, 51% of studies had WCLFU >FI. CONCLUSION: The median FI among all trials was 23, and WCLFU exceeded FI in 42%. Comparative trials in solid tumors supporting approval through the accelerated pathway are more fragile compared to trials approved through the regular pathway, an observation likely explained by a lower sample size in the experimental arm.

Network Meta-analysis Comparing Efficacy, Safety and Tolerability of Anti-PD-1/PD-L1 Antibodies in Solid Cancers.

Background: Multiple anti-PD-1/PD-L1 antibodies have been approved, and in some diseases, there is a choice of more than one. Comparative efficacy, safety and tolerability are unknown. Methods: Randomized trials (RCTs) supporting the registration of single agent anti-PD1 or anti-PDL1 inhibitors between 2015-2019 were identified. We extracted the hazard ratio (HR) for overall survival (OS) and calculated the odds ratio (OR) for commonly reported safety and tolerability outcomes. We then performed a network meta-analysis, reporting multiple pair-wise comparisons between different anti-PD-1/PD-L1 antibodies. Results: Sixteen RCTs comprising 10673 patients were included; 10 in non-small-cell lung cancer, 2 in melanoma, 2 in head and neck squamous cell carcinoma and 2 in urothelial cancer. Compared to pembrolizumab, efficacy was similar for nivolumab (HR: 1.02 95% CI: 0.91-1.14) and for atezolizumab (HR: 0.97 95% CI: 0.85-1.10), however, avelumab appeared inferior (HR: 1.30, 95% CI: 1.06-1.56). Pembrolizumab showed similar odds of serious adverse events (SAEs) as nivolumab (OR: 1.12, 95% CI: 0.56-2.27) and atezolizumab (OR: 1.05, 95% CI: 0.55-2.04). Compared to nivolumab, atezolizumab was associated with more SAEs (OR: 2.14, 95% CI: 1.47-3.12). Avelumab had the lowest odds of grade 3-4 adverse events compared to pembrolizumab (OR: 0.42, 95% CI: 0.24-0.74), nivolumab (OR: 0.38, 95% CI: 0.24-0.62) and atezolizumab (OR: 0.21, 95% CI: 0.14-0.33). The odds of treatment discontinuation without progression were similar between nivolumab and atezolizumab (OR: 1.20, 95% CI: 0.73-2.00), and between pembrolizumab and nivolumab (OR: 1.35, 95% CI: 0.83-2.17), but was higher with atezolizumab compared to nivolumab (OR: 2.56, 95% CI: 1.29-5.00). Pembrolizumab was associated with higher OR of immune-related adverse events (IRAEs) compared to nivolumab (OR: 2.12, 95% CI: 1.49-3.03) and atezolizumab (OR: 1.63, 95% CI: 1.09-2.43). Conclusions: Pembrolizumab, nivolumab, and atezolizumab have similar efficacy. Avelumab appears less efficacious. Safety and tolerability seem better with avelumab, but worse with atezolizumab and pembrolizumab.

Fragility index of trials supporting approval of anti-cancer drugs in common solid tumours.

BACKGROUND: The Fragility Indexquantifies the reliability of positive trials by estimating the number of events, which would change statistically significant results to non-significant results. METHODS: We identified randomized trials supporting drug approvals by the US FDA between 2009 and 2019 in lung, breast, prostate, and colon cancers and in melanoma. We reconstructed survival tablesand calculated the number of events, which would result in a non-significant result for the primary endpoint. The FI was then compared to the number of patients in each trial who withdrew consent or were lost to follow-up. Regression analyses were used to explore associations between RCT characteristics and FI and trials in which FI was lower or equal to number of participants who withdrew consent or were lost to follow-up. RESULTS: Among 81 RCTs, the median FI was 28. The median number of patients who withdrew consent or were lost to follow up was 27. FI was equal or lower than the number of patients who withdrew consent or were lost to follow-up in 47 trials (58%). There was a modest increase in FI over time (p = 0.02). Trials with overall survival as the primary endpoint (p = 0.006) and those in the palliative setting (p < 0.001) had lower FI. There was no association with trial sample size or duration of follow-up. FINDINGS: Statistical significance of RCTs in common solid tumours can be reversed often with a small number of additional events. Post-approval RCTs or real-world data analyses should be performed to ensure results of registration trials are robust.

Implementing DPYD*2A Genotyping in Clinical Practice: The Quebec, Canada, Experience.

BACKGROUND: Fluoropyrimidines are used in chemotherapy combinations for multiple cancers. Deficient dihydropyrimidine dehydrogenase activity can lead to severe life-threatening toxicities. DPYD*2A polymorphism is one of the most studied variants. The study objective was to document the impact of implementing this test in routine clinical practice. METHODS: We retrospectively performed chart reviews of all patients who tested positive for a heterozygous or homozygous DPYD*2A mutation in samples obtained from patients throughout the province of Quebec, Canada. RESULTS: During a period of 17 months, 2,617 patients were tested: 25 patients tested positive. All were White. Twenty-four of the 25 patients were heterozygous (0.92%), and one was homozygous (0.038%). Data were available for 20 patients: 15 were tested upfront, whereas five were identified after severe toxicities. Of the five patients confirmed after toxicities, all had grade 4 cytopenias, 80% grade ≥3 mucositis, 20% grade 3 rash, and 20% grade 3 diarrhea. Eight patients identified with DPYD*2A mutation prior to treatment received fluoropyrimidine-based chemotherapy at reduced initial doses. The average fluoropyrimidine dose intensity during chemotherapy was 50%. No grade ≥3 toxicities were observed. DPYD*2A test results were available in an average of 6 days, causing no significant delays in treatment initiation. CONCLUSION: Upfront genotyping before fluoropyrimidine-based treatment is feasible in clinical practice and can prevent severe toxicities and hospitalizations without delaying treatment initiation. The administration of chemotherapy at reduced doses appears to be safe in patients heterozygous for DPYD*2A. IMPLICATIONS FOR PRACTICE: Fluoropyrimidines are part of chemotherapy combinations for multiple cancers. Deficient dihydropyrimidine dehydrogenase activity can lead to severe life-threatening toxicities. This retrospective analysis demonstrates that upfront genotyping of DPYD before fluoropyrimidine-based treatment is feasible in clinical practice and can prevent severe toxicities and hospitalizations without delaying treatment initiation. This approach was reported previously, but insufficient data concerning its application in real practice are available. This is likely the first reported experience of systematic DPYD genotyping all over Canada and North America as well.

Comparison of treatment-related adverse events of different Cyclin-dependent kinase 4/6 inhibitors in metastatic breast cancer: A network meta-analysis.

BACKGROUND: Palbociclib, ribociclib and abemaciclib have all been approved in combination with endocrine therapy in hormone-receptor positive, HER2 negative metastatic breast cancer. While the efficacy of these drugs appears similar, differences in safety and tolerability are apparent. METHODS: We searched PubMed and ASCO, ESMO and SABCS proceedings to identify randomized trials of palbociclib, ribociclib and abemaciclib. Data on common and serious adverse events (AE) were extracted for each approved drug. The odds ratio for each AE and the hazard ratio for progression-free survival were calculated relative to endocrine therapy alone. A network meta-analysis was then performed for each endocrine therapy backbone (aromatase inhibitor (AI) or fulvestrant) to compare ribociclib and abemaciclib to palbociclib. RESULTS: 8 trials were included in the analysis and comprised 2799 patients receiving cyclin-dependent kinase 4/6 inhibitors palbociclib: 873 patients; ribociclib: 1153 patients; abemaciclib: 773 patients. In 5 trials (1524 patients), the endocrine therapy backbone was an AI and in 3 trials (1275 patients) it was fulvestrant. Compared to palbociclib, ribociclib and abemaciclib showed significantly lower grade 3-4 neutropenia, but significantly higher GI toxicity. Treatment discontinuation was higher with abemaciclib than other drugs. Efficacy of the 3 drugs was similar. Compared to palbociclib, for AI backbone, the HR for PFS for ribociclib was 0.98 and for abemaciclib 1.02. For fulvestrant backbone, the HR were 0.88 and 0.93 respectively. CONCLUSIONS: Palbociclib, ribociclib and abemaciclib have comparable efficacy, but differences in safety and tolerability. Abemaciclib has worse tolerability with significantly higher treatment discontinuation likely due to GI toxicity.

Evolution in the risk of adverse events of adjuvant endocrine therapy in postmenopausal women with early-stage breast cancer.

BACKGROUND: Adjuvant endocrine therapy is a gold standard in early-stage, hormone receptor positive breast cancer. In postmenopausal women, aromatase inhibitors (AIs) are associated with improved outcome compared to tamoxifen monotherapy. Differences in the toxicity profiles of these drugs are described; however, little is known about whether the risk of adverse events changes over time. METHODS: Sequential reports of large, randomized, adjuvant endocrine therapy trials comparing AIs to tamoxifen were reviewed. Data on pre-specified adverse events were extracted including cardiovascular events, bone fractures, cerebrovascular disease, endometrial cancer, secondary malignancies excluding breast cancer, venous thrombosis and death without recurrence. Odds ratios (ORs) were calculated for each adverse event at each time over the course of follow-up. The change in the ORs for adverse events over time was evaluated using weighted linear regression. RESULTS: Analysis included 21 reports of 7 trials comprising 30,039 patients and reporting outcomes between 28 and 128 months of follow-up. Compared to tamoxifen, AIs use was associated with a significant reduction in the magnitude of increased odds of bone fracture over time (ß = - 0.63, p = 0.013). There was a non-significant decrease in the magnitude of reduced odds of secondary malignancies over time (ß = 0.448, p = 0.094). The differences in other toxicity profiles between AIs and tamoxifen did not change significantly over time. CONCLUSIONS: The increased risk of bone fractures associated with adjuvant AIs falls over time and after discontinuation of treatment. Differences in other toxicities between AIs and tamoxifen do not change significantly over time including a persistently elevated risk of cardiovascular events.

Influence of Competing Risks on Estimates of Recurrence Risk and Breast Cancer-specific Mortality in Analyses of the Early Breast Cancer Trialists Collaborative Group.

Early-stage breast cancer (BC) is a curable disease with many patients dying of causes other than BC. The influence of non-BC death and other competing risks on the interpretation of Kaplan-Meier (KM)-based analyses for BC-specific outcomes are unknown. We searched the Oxford University website to identify all meta-analyses published by the Early Breast Cancer Trialists Collaborative Group (EBCTCG) between 2005 and 2018. The potential influence of competing risks was estimated using a validated multivariable linear model that predicts the difference between KM and cumulative incidence function (CIF) on estimates of BC-specific outcomes. The initial search identified 14 EBCTCG papers, 10 (71%) reported data on BC and competing events. Eight (80%) had a relative difference between KM and the competing risk adjusted estimates exceeding 10%. The median relative difference was 28.4% for local-recurrence; 16.8% for distant-recurrence, and 6.7% for BC-specific mortality. There was a 18.9% relative difference between KM and CIF adjusted analyses beyond 10 years. The use of KM-based methods when competing risks are present biases risk estimates in studies of early BC especially for uncommon outcomes such as local recurrence. The use of CIF to calculate BC-specific outcomes may be preferable in this setting.

Integrin ανß6 Protein Expression and Prognosis in Solid Tumors: A Meta-Analysis.

BACKGROUND AND OBJECTIVE: Integrins are a family of adhesion receptor proteins that provide signaling from the extracellular matrix to the cytoplasm. They have been associated with cancer by promoting migration, invasion, metastasis, and survival. ανß6 integrin is upregulated in several tumors. Here, we evaluate the prognostic impact of ανß6 integrin protein expression in solid tumors. METHODS: A systematic search of electronic databases identified publications exploring the effect of ανß6 integrin on overall survival (OS). Hazard ratios (HRs) were pooled in a meta-analysis using generic inverse variance and random effects modeling. Subgroup analyses were conducted based on tumor site, tumor stage, antibody used for immunohistochemistry (IHC) and method for extraction of the HR. A meta-regression explored the influence of clinical variables on the magnitude of effect of ανß6 integrins on OS. RESULTS: Seventeen studies comprising 5795 patients met the inclusion criteria. High ανß6 integrin expression in tumors was associated with worse OS (HR 1.65, 95% confidence interval [CI] 1.32-2.06; Cochran's Q p < 0.001, I2 = 81%). Adverse outcomes were similar in all tumor sites (subgroup difference p = 0.10), with the strongest association between ανß6 integrins and OS in gastric cancer (HR 2.20, 95% CI 1.71-2.83) and the lowest in head and neck cancer (HR 1.21, 95% CI 0.79-1.83). There was no significant difference between early-stage and metastatic cancer, type of IHC antibodies, and analysis methods. CONCLUSIONS: High expression of ανß6 integrins is associated with adverse survival outcome in several tumors. Prospective studies evaluating the prognostic impact of ανß6 integrin and its role as a therapeutic target are warranted.