Use of External Control Cohorts in Pediatric Brain Tumor Clinical Trials

Why, when, and how to consider external control cohorts in pediatric brain tumor clinical trials.

Association between antibiotics and adverse oncological outcomes in patients receiving targeted or immune-based therapy for hepatocellular carcinoma

Background & Aims

Immune checkpoint inhibitors (ICIs) alone or in combination with other ICIs or vascular endothelial growth factor pathway inhibitors are therapeutic options in unresectable/metastatic hepatocellular carcinoma (HCC). Whether antibiotic (ATB) exposure affects outcome remains unclear.

Methods

This study retrospectively analysed an FDA database including 4,098 patients receiving ICI (n = 842) either as monotherapy (n = 258) or in combination (n = 584), tyrosine kinase inhibitor (TKI) (n = 1,968), vascular endothelial growth factor pathway inhibitors (n = 480), or placebo (n = 808) as part of nine international clinical trials. Exposure to ATB within 30 days before or after treatment initiation was correlated with overall survival (OS) and progression-free survival (PFS) across therapeutic modality before and after inverse probability of treatment weighting (IPTW).

Results

Of 4,098 patients with unresectable/metastatic HCC, of which 39% were of hepatitis B aetiology and 21% were of hepatitis C aetiology, 83% were males with a median age of 64 years (range 18-88), a European Collaborative Oncology Group performance status of 0 (60%), and Child-Pugh A class (98%). Overall, ATB exposure (n = 620, 15%) was associated with shorter median PFS (3.6 months in ATB-exposed vs. 4.2 months; hazard ratio [HR] 1.29; 95% CI 1.22, 1.36) and OS (8.7 months in ATB-exposed vs. 10.6 months; HR 1.36; 95% CI 1.29, 1.43). In IPTW analyses, ATB was associated with shorter PFS in patients treated with ICI (HR 1.52; 95% CI 1.34, 1.73), TKI (HR 1.29; 95% CI 1.19, 1.39), and placebo (HR 1.23; 95% CI 1.11, 1.37). Similar results were observed in IPTW analyses of OS in patients treated with ICI (HR 1.22; 95% CI 1.08, 1.38), TKI (HR 1.40; 95% CI 1.30, 1.52), and placebo (HR 1.40; 95% CI 1.25, 1.57).

Conclusions

Unlike other malignancies where the detrimental effect of ATB may be more prominent in ICI recipients, ATB is associated with worse outcomes in this study across different therapies for HCC including placebo. Whether ATB is causally linked to worse outcomes through disruption of the gut-liver axis remains to be demonstrated in translational studies.

Impact and Implications

A growing body of evidence suggests the host microbiome, frequently altered by antibiotic treatment, as an important outcome predictor in the context of immune checkpoint inhibitor therapy. In this study, we analysed the effects of early antibiotic exposure on outcomes in almost 4,100 patients with hepatocellular carcinoma treated within nine multicentre clinical trials. Interestingly, early exposure to antibiotic treatment was associated with worse outcomes not only in patients treated with immune checkpoint inhibitors but also in those treated with tyrosine kinase inhibitors and placebo. This is in contrast to data published in other malignancies, where the detrimental effect of antibiotic treatment may be more prominent in immune checkpoint inhibitor recipients, highlighting the uniqueness of hepatocellular carcinoma given the complex interplay between cirrhosis, cancer, risk of infection, and the pleiotropic effect of molecular therapies for this disease.

Abstract A025: Enrollment of older adults in small cell lung cancer (SCLC) clinical trials compared with population-based U.S. incidence estimates

Background: Small cell lung cancer (SCLC) is an aggressive form of cancer characterized by rapid progression, early metastases, and poor prognosis. Clinical trials (CTs) leading to approval of various classes of medical products have recently increased the treatment options available for SCLC patients. Older adults ≥65 years of age are historically under-enrolled in CTs. The U.S. population continues to age. There is often limited evidence supporting safety and effectiveness of treatment among this population because of disproportionate enrollment of older adults in CTs. To characterize patterns of SCLC CT enrollment by age, selected SCLC CTs (immunotherapy and cytotoxic agents) were compared to U.S. SCLC incidence data. Methods: We identified six CTs for treatment of SCLC to support marketing applications submitted to the FDA between 2018-2019. Descriptive statistics based on the pooled CT data were calculated and compared with incident U.S. SCLC cases diagnosed between the same period, using data from the National Cancer Institute Surveillance, Epidemiology, and End Results (SEER) Program. While SEER is a U.S. population-based representative sample, data from the trials included patients outside the U.S. that were submitted to support marketing applications with applicability to U.S. clinical practice. Results: A total of 1,642 patients were enrolled in the six included SCLC CTs. In this sample, 42.9% were age ≥65 years, compared to 66.6% of incident U.S. SCLC cases. This disparity persists with increasing age: 8.5% of CT enrollees were age ≥75 years and 1.8% of CT enrollees were age ≥85 years, compared to 27.5% and 4.5% of incident U.S. SCLC cases, respectively. Discussion: Based on these findings, older adults are underrepresented in SCLC CTs, while representing a substantially larger proportion of incident U.S. cases. The number of SCLC patients over 65 years is likely to increase the U.S. population continues to age. Aging presents specific challenges with respect to cancer care due to increased presence of comorbidities and the potential for variance in patient and provider treatment preferences, which might partially explain the results. These results demonstrate an opportunity to evaluate and fix barriers to trial entry for older adults to ensure representative evidence generation that is reflective of the epidemiology of the disease and the real-world population.

Citation Format: Felice Yang, Oladimeji Akinboro, Catherine Lerro, Fatima Rizvi, Pallavi Mishra-Kalyani, Paul G. Kluetz, Harpreet Singh, Donna R. Rivera. Enrollment of older adults in small cell lung cancer (SCLC) clinical trials compared with population-based U.S. incidence estimates [abstract]. In: Proceedings of the AACR Special Conference: Aging and Cancer; 2022 Nov 17-20; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_1):Abstract nr A025.

Abstract A024: Enrollment of older adults in non-small cell lung cancer (NSCLC) clinical trials compared with population-based U.S. incidence

Background: Lung cancer is frequently diagnosed in older adults. As the U.S. population continues to age, understanding treatment effects in lung cancer patients ≥65 years of age is increasingly important. Despite this trend, clinical trials (CTs) have historically under-enrolled older adults, creating a disparity between trial and real-world populations. Disproportionate enrollment can create challenges in understanding utilization in subpopulations. Due to increased interest in PD-(L)1 inhibitors for non-small cell lung cancer (NSCLC) treatment, CTs examining PD-(L)1 inhibitors in the first-line (1L) setting were selected to evaluate enrollment disparity in NSCLC immunotherapy. Methods: We identified 11 CTs that investigated 1L NSCLC anti-PD-(L)1 regimens submitted to the FDA between 2016 and 2020. Descriptive statistics were calculated based on the pooled dataset and compared with incident U.S. NSCLC cases diagnosed between 2015 and 2019, based on data from the National Cancer Institute Surveillance, Epidemiology, and End Results (SEER) Program. While SEER is a U.S. population-based representative sample, data from the trials included patients outside the U.S. that were submitted to support marketing applications with applicability to U.S. clinical practice. Results: A total of 7,030 patients enrolled in anti-PD-(L)1 CTs were included. In this sample, 48.2% were age ≥65 years, compared to 70.4% of incident U.S. NSCLC cases. This disparity persists with increasing age: 10.3% of enrollees were age ≥75 years and 0.5% of enrollees were age ≥85 years, compared to 34.3% and 7.2% of incident U.S. NSCLC cases, respectively. Discussion: Based on our results, older adults continue to be underrepresented in NSCLC anti-PD-(L)1 CTs, contributing to a potential treatment evidence gap. This gap widens with age and patients age ≥85 years constitute a miniscule portion (0.5%) of the CT cohort. Meanwhile, more patients will move into this group as the population ages. Aging can be associated with comorbidities and the potential for variance in patient and provider treatment preferences, which are important to acknowledge as these aspects may, in part, explain the results. Nonetheless, the gap in the number of older adults enrolled in this CT sample compared with SEER incidence demonstrates a clear need to improve recruitment in this underrepresented population. Awareness of trial-level and system-level barriers is necessary to minimize disparities. Additional research using tools such as real-world data to examine current treatment utilization, patient factors, and outcomes among underrepresented populations would increase the depth of evidence to address this disparity effectively.

Citation Format: Felice Yang, Jonathon Vallejo, Oladimeji Akinboro, Catherine Lerro, Pallavi Mishra-Kalyani, Shenghui Tang, Paul G. Kluetz, Harpreet Singh, Donna R. Rivera. Enrollment of older adults in non-small cell lung cancer (NSCLC) clinical trials compared with population-based U.S. incidence [abstract]. In: Proceedings of the AACR Special Conference: Aging and Cancer; 2022 Nov 17-20; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_1):Abstract nr A024.

FDA Approval Summary: Atezolizumab and Durvalumab in Combination with Platinum-Based Chemotherapy in Extensive Stage Small Cell Lung Cancer

The U.S. Food and Drug Administration (FDA) granted approval to atezolizumab and durvalumab in March of 2019 and 2020, respectively, for use in combination with chemotherapy for first-line treatment of patients with extensive stage small cell lung cancer. These approvals were based on data from two randomized controlled trials, IMpower133 (atezolizumab) and CASPIAN (durvalumab). Both trials demonstrated an improvement in overall survival (OS) with anti-programmed death ligand 1 antibodies when added to platinum-based chemotherapy as compared with chemotherapy alone. In IMpower133, patients receiving atezolizumab with etoposide and carboplatin demonstrated improved OS (hazard ratio [HR], 0.70; 95% confidence interval [CI], 0.54-0.91; p = .0069), with median OS of 12.3 months compared with 10.3 months in patients receiving etoposide and carboplatin. In CASPIAN, patients receiving durvalumab with etoposide and either cisplatin or carboplatin also demonstrated improved OS (HR, 0.73; 95% CI, 0.59-0.91; p = .0047) with median OS of 13.0 months compared with 10.3 months in patients receiving etoposide and either cisplatin or carboplatin. The safety profiles of both drugs were generally consistent with known toxicities of immune-checkpoint inhibitor therapies. This review summarizes the FDA perspective and data supporting the approval of these two agents. IMPLICATIONS FOR PRACTICE: Effective therapeutic options for small cell lung cancer (SCLC) are limited, and there has been modest improvement in the overall survival (OS) of patients with SCLC over the past 3 decades. The approvals of atezolizumab and of durvalumab in combination with chemotherapy for first-line treatment of patients with extensive stage SCLC represent the first approved therapies with OS benefit for this patient population since the approval of etoposide in combination with other approved chemotherapeutic agents. Additionally, the efficacy results from IMpower133 and CASPIAN lay the groundwork for possible further evaluation in other treatment settings in this disease.

FDA Accelerated Approval of Pembrolizumab for Recurrent Locally Advanced or Metastatic Merkel Cell Carcinoma

On December 19, 2018, the Food and Drug Administration granted accelerated approval to pembrolizumab (KEYTRUDA, Merck & Co. Inc., Whitehouse Station, NJ) for adult and pediatric patients with recurrent locally advanced or metastatic Merkel cell carcinoma (MCC). Approval was based on Cancer Immunotherapy Trials Network protocol 9, also known as KEYNOTE-017 (NCT02267603), a multicenter, nonrandomized, open-label trial that enrolled 50 patients with recurrent locally advanced or metastatic MCC who had not received prior systemic therapy for their advanced disease. The major efficacy outcome measures were overall response rate (ORR) and response duration assessed by blinded independent central review per RECIST 1.1. The ORR was 56% (95% confidence interval: 41, 70) with a complete response rate of 24%. The median response duration was not reached. Among the 28 patients with responses, 96% had response durations of greater than 6 months and 54% had response durations of greater than 12 months. The most common adverse reactions of pembrolizumab reported in at least 20% of patients who received pembrolizumab as a single agent were fatigue, musculoskeletal pain, decreased appetite, pruritus, diarrhea, nausea, rash, pyrexia, cough, dyspnea, constipation, pain, and abdominal pain. IMPLICATIONS FOR PRACTICE: This report presents key information on the basis for the Food and Drug Administration's accelerated approval of pembrolizumab for the treatment of recurrent locally advanced or metastatic Merkel cell carcinoma, including efficacy and safety information. This approval provides patients and physicians with an additional treatment option for this aggressive and life-threatening carcinoma.

Analysis of time-to-treatment discontinuation of targeted therapy, immunotherapy, and chemotherapy in clinical trials of patients with non-small-cell lung cancer

BACKGROUND

Pragmatic end points, such as time-to-treatment discontinuation (TTD), defined as the date of starting a medication to the date of treatment discontinuation or death has been proposed as a potential efficacy end point for real-world evidence (RWE) trials, where imaging evaluation is less structured and standardized.

PATIENTS AND METHODS

We studied 18 randomized clinical trials of patients with metastatic non-small-cell lung cancer (mNSCLC), initiated after 2007 and submitted to U.S. Food and Drug Administration. TTD was calculated as date of randomization to date of discontinuation or death and compared to progression-free survival (PFS) and overall survival (OS) across all patients, as well as in treatment-defined subgroups [EGFR mutation-positive treated with tyrosine kinase inhibitor (TKI), EGFR wild-type treated with TKI, ALK-positive treated with TKI, immune checkpoint inhibitor (ICI), chemotherapy doublet with maintenance, chemotherapy monotherapy].

RESULTS

Overall across 8947 patients, TTD was more closely associated with PFS (r = 0.87, 95% CI 0.86-0.87) than with OS (0.68, 95% CI 0.67-0.69). Early TTD (PFS-TTD ≥ 3 months) occurred in 7.7% of patients overall, and was more common with chemo monotherapy (15.0%) while late TTD (TTD-PFS ≥ 3 months) occurred in 6.0% of patients overall, and was more common in EGFR-positive and ALK-positive patients (12.4% and 22.9%). In oncogene-targeted subgroups (EGFR positive and ALK positive), median TTDs (13.4 and 14.1 months) exceeded median PFS (11.4 and 11.3 months).

CONCLUSIONS

At the patient level, TTD is associated with PFS across therapeutic classes. Median TTD exceeds median PFS for biomarker-selected patients receiving oncogene-targeted therapies. TTD should be prospectively studied further as an end point for pragmatic randomized RWE trials only for continuously administered therapies.

FDA analyses of survival in older adults with metastatic non-small cell lung cancer in controlled trials of PD-1/PD-L1 blocking antibodies

BACKGROUND

Among patients with newly diagnosed non-small cell lung cancer (NSCLC), approximately 70% occur in those above 65 years of age and more than half are metastatic or locally advanced NSCLC.

METHODS

Retrospective analyses pooling data across 4 randomized clinical trials comparing programmed death 1 receptor (PD-1) or programmed death ligand 1 (PD-L1) to docetaxel for the treatment of patients with advanced or metastatic NSCLC with disease progression on or after a platinum-containing therapy were conducted. Demographics, efficacy, and safety data from these trials were pooled and aggregated based on age. The relative treatment effects on overall survival (OS) across age groups were evaluated using Kaplan-Meier methodology. A meta-analysis was performed comparing OS across age groups treated with PD-1/PD-L1 blocking antibodies compared with those treated with docetaxel, as a common control arm across trials. A Cox Proportional Hazards model, stratified by clinical trial, was used and a univariate and multivariate adjusted analysis of OS to further identify trends in efficacy across age groups.

RESULTS

Among patients treated with PD-1/PD-L1 blocking antibodies enrolled across the 4 clinical trials, 42% were >65 years of age, 99% had ECOG performance status of 0-1, 75% had received 1 prior therapy, and 76% were diagnosed with Stage IV disease. In the pooled analysis of 2,824 patients across both arms, the treatment effects in age-defined subgroups were similar, with a hazard ratios (HR), unadjusted or adjusted, for OS of 0.71 (95% confidence interval 0.63, 0.80) in patients <65 years and 0.66 (0.57, 0.76) in patients ≥65 years of age. In patients ≥70 years, the HR for OS was 0.67 (0.55. 0.82) and in patients ≥ 75 years, the HR was 0.81 (0.58, 1.13). Estimated median OS in patients receiving PD-1/PD-L1 blocking antibodies versus docetaxel was 14.5 months versus 8.8 months in patients <65 years, 14.2 months versus 9 months in patients ≥65 years, 14.1 versus 9.2 months in patients ≥70 years, and 14.7 versus 9.5 months in the patients ≥75years. Grade 3 or 4 treatment-related adverse events with PD-1/PD-L1 blocking antibodies were less frequent in patients ≥75 years (23%) compared to patients> 65 year ( 49%) and <65 years (47%), as were serious adverse events (30%, 32.5%, 15%); however, treatment-emergent adverse events leading to discontinuation of treatment (7%, 7%, and 5%) in those subgroups ≤65 years, >65 years, and >75 years, respectively, were similar.

CONCLUSIONS

Patients 65 and older with advanced and metastatic NSCLC, including those ≥75 years, seem to derive similar survival benefits from treatment with PD-1/PD-L1 blocking antibodies as patients <65 years of age. Patients 75 and older enrolled on these trials appear to tolerate PD-1/PD-L1 blocking antibodies and have a lower incidence of grade 3 or 4 treatment-emergent adverse events compared to the subgroup of patients <65 years of age.

FDA Approval Summary: Pembrolizumab for the Treatment of Patients with Unresectable or Metastatic Melanoma

On December 18, 2015, the FDA granted regular approval to pembrolizumab (KEYTRUDA; Merck Sharp & Dohme Corp.) for treatment of patients with unresectable or metastatic melanoma based on results of two randomized, open-label, active-controlled clinical trials. In trial PN006, 834 patients with ipilimumab-naïve metastatic melanoma were randomized (1:1:1) to pembrolizumab 10 mg/kg i.v. every 2 or 3 weeks until disease progression or ipilimumab 3 mg/kg every 3 weeks for up to four doses. In trial PN002, 540 patients with ipilimumab-refractory metastatic melanoma were randomized (1:1:1) to pembrolizumab 2 or 10 mg/kg i.v. every 3 weeks or to investigator's choice of chemotherapy. In trial PN006, patients randomized to pembrolizumab demonstrated a statistically significant improvement in overall survival compared with ipilimumab [every-2-week arm: hazard ratio (HR) = 0.63; 95% confidence interval (CI), 0.47-0.83; P < 0.001; every-3-week arm: HR = 0.69; 95% CI, 0.52-0.90; P = 0.004]. In both trials, patients receiving pembrolizumab demonstrated statistically significant improvements in progression-free survival. The most common (≥2%) immune-mediated adverse reactions in a pooled safety analysis were hypothyroidism, pneumonitis, and hyperthyroidism. Key considerations for approval were determination of pembrolizumab dose and interpretation of tumor response-based endpoints using RECIST or immune-related RECIST. Clin Cancer Res; 23(19); 5661-5. ©2017 AACR.