Cell proliferation, drug distribution and therapeutic effects in relation to the vascular system of solid tumours

In this perspective, the authors summarise some properties of the solid tumour micro-environment that have been explored during the last 55 years. It is well established that the concentrations of nutrients, including oxygen, decrease with increasing distance from tumour blood vessels, and that low extracellular pH is found in nutrient-poor regions. Cell proliferation is dependent on nutrient metabolites and decreases in regions distal from patent blood vessels. Proliferating cells cause migration of neighbouring cells further from blood vessels where they may die, and their breakdown products pass into regions of necrosis. Anticancer drugs reach solid tumours via the vascular system and establish concentration gradients such that drug concentration within tumours may be quite variable. Treatment with chemotherapy such as doxorubicin or docetaxel can kill well-nourished proliferating cells close to blood vessels, thereby interrupting migration toward necrotic regions and lead to re-oxygenation and renewed proliferation of distal cells, as can occur with radiotherapy. This effect leads to the paradox that cancer treatment can rescue cells that were destined to die in the untreated tumour. Renewed and sometimes accelerated repopulation of surviving tumour cells can counter the effects of cell killing from repeated treatments, leading to tumour shrinkage and regrowth without changes in the intrinsic sensitivity of cells to the administered treatment. Strategies to prevent these effects include the combined use of chemotherapy with agents that selectively kill hypoxic tumour cells, including inhibitors of autophagy, since this is a process that may allow recycling of cellular macromolecules from dying cells and improve their survival.

Lack of cognitive impairment in long-term survivors of colorectal cancer

Background

Our longitudinal study reported cognitive impairment in 43% of people following diagnosis of localised colorectal cancer (CRC) versus 15% in healthy controls (p < 0.001) and 50% versus 13% 1–2 years later (p < 0.001). Here we evaluate cognitive function and neuroimaging in a subgroup at long-term follow-up.

Patients and methods

Cancer-free Australian participants in the study, and controls, completed cognitive and functional assessments. Neuroimaging was optional. Blood tests included inflammatory markers, clotting factors, sex hormones and apolipoprotein E genotype. The primary endpoint was demographically and practice effect-corrected cognitive scores comparing CRC survivors with controls over time examined using a linear mixed model, adjusted for baseline performance. Secondary endpoints included cognitive impairment rate using the Global Deficit Score [GDS > 0.5], Functional Deficit Score, blood results and neuroimaging.

Results

The study included 25 CRC survivors (60% men, median age 72) at mean 9 years after baseline (9 received adjuvant chemotherapy) and 25 controls (44% men, median age 68) at mean 6 years after baseline. There were no significant differences in cognitive scores or proportion with cognitive impairment (16 vs. 8%) between survivors and controls and no evidence of accelerated ageing in CRC survivors. Baseline cognitive performance predicted for subsequent cognitive function. There were no differences in functional tests or blood tests between groups. In 18 participants undergoing neuroimaging, 10 CRC survivors had higher myoinositol levels than 8 controls, and lower volume in the right amygdala and caudate and left hippocampal regions.

Conclusions

There was no difference in cognitive capacity and function between CRC survivors and controls 6–12 years after diagnosis. Differences in neuroimaging require confirmation in a larger sample.

Highlights

• No evidence of long term cognitive impairment in colorectal cancer survivors compared to controls 6–12 years after diagnosis

• No evidence of accelerated cognitive ageing in colorectal cancer survivors

• No evidence of long-term functional impairment in colorectal cancer survivors

Supplementary Information

The online version contains supplementary material available at 10.1007/s00520-022-07008-3.

Priorities for cancer research in low- and middle-income countries: a global perspective

Cancer research currently is heavily skewed toward high-income countries (HICs), with little research conducted in, and relevant to, the problems of low- and middle-income countries (LMICs). This regional discordance in cancer knowledge generation and application needs to be rebalanced. Several gaps in the research enterprise of LMICs need to be addressed to promote regionally relevant research, and radical rethinking is needed to address the burning issues in cancer care in these regions. We identified five top priorities in cancer research in LMICs based on current and projected needs: reducing the burden of patients with advanced disease; improving access and affordability, and outcomes of cancer treatment; value-based care and health economics; quality improvement and implementation research; and leveraging technology to improve cancer control. LMICs have an excellent opportunity to address important questions in cancer research that could impact cancer control globally. Success will require collaboration and commitment from governments, policy makers, funding agencies, health care organizations and leaders, researchers and the public.

Clinical research in oncology: in memory of Professor Gordon McVie

Gordon McVie campaigned throughout his career for merging scientific and clinical expertise and for investigating the underlying pharmacokinetics and pharmacodynamics in clinical trials. This need remains highly relevant today when most cancer clinical trials investigate agents that target a known molecular pathway, yet anticancer drug development has changed minimally from that used for chemotherapy when more was better and substantial toxicity inevitable. Here, I summarise some common problems that confound current drug development, including problems in interpreting results of phase 3 randomised trials, as well as trials investigating personalised medicine.

Design of placebo-controlled randomized trials of anticancer agents: Ethical considerations based on a review of published trials

BACKGROUND

Limited information exists about the design of placebo-controlled cancer trials. Through a systematic review of trials published in 2013, we describe placebo use in randomized trials testing anticancer agents and analyze strategies that increase exposure to the experimental regimen.

METHODS

Trials were classified as add-on (placebo in combination with standard treatment) or placebo-only. Strategies to allow more than half of the participants to receive the experimental regimen were reviewed. The risk-benefit ratio of receiving the experimental agent was considered favorable if the difference in primary outcome was significant (p ≤ 0.05), neutral if there was no significant difference in the primary outcome and the experimental agent did not add substantial toxicity, and unfavorable otherwise.

RESULTS

Eighty trials were included (32,694 participants). Most trials were add-on (69%). The risk-benefit outcome was favorable, neutral, and unfavorable to the experimental agent in 52%, 32%, and 16% of placebo-only trials and 25%, 53%, and 22%, respectively, of add-on trials. Four strategies increased exposure to the experimental regimen: one-way crossover (23%), uneven randomization (21%), three-arms (13%), and randomized discontinuation design (4%); these strategies were used more often in placebo-only trials.

CONCLUSION

A minority of participants received placebo alone and strategies to increase experimental exposure were used commonly. Fewer than half of the studies had favorable outcomes, thus defending the use of placebo controls, when there is no established treatment. Strategies that increase patient exposure to experimental agents rather than placebo may expose them to non-beneficial, sometimes toxic, experimental agents.

Low-Dose Abiraterone in Metastatic Prostate Cancer: Is It Practice Changing? Facts and Facets

PURPOSE

It is projected that approximately 50,000 new cases of prostate cancer will be diagnosed in 2020 in India. Survival has improved because of the development of effective drugs such as abiraterone acetate, but universal accessibility to treatment is not always possible because of cost constraints in lower- and middle-income countries. Recently, the National Comprehensive Cancer Network (NCCN) has included low-dose abiraterone (250 mg/day) with food as an alternative treatment option to full-dose abiraterone (1,000 mg/day) fasting.

METHODS

The Science and Cost Cancer Consortium conducted a survey to evaluate the use of abiraterone in India and the opinions of medical oncologists about using low-dose treatment. Modeling was used to estimate potential financial benefits to individual patients and to estimate overall costs of health care in India if low-dose abiraterone is prescribed.

RESULTS

Of 251 Indian medical oncologists who were invited to participate in the survey, 125 provided their e-mail address and received the survey; 118 responded (47% of the total). Of these, 25% were not aware of the recent NCCN recommendation, 55% were already prescribing low-dose abiraterone when resources were limited, 7% had already changed their practice, and 29% agreed to switch to a universal practice of using low-dose abiraterone with food; 9% of practitioners would not use low-dose abiraterone. Estimated mean per patient savings was US$3,640, with annual savings of US$182 million in India.

CONCLUSION

Use of lower-dose abiraterone would increase access to treatment in India and globally and lead to large cost savings.

Updating Reports of Phase 3 Clinical Trials for Cancer

Importance

Phase 3 randomized clinical trials (RCTs) are usually reported after a predetermined number of events (death or disease progression) have occurred, when survival curves remain poorly defined. Updated reports are important in providing mature data.

Objectives

To evaluate the proportion of phase 3 RCTs for cancer that are updated and the factors that are associated with updating them and, for updated trials, to compare initial and updated results.

Design, Setting, and Participants

This study identified reports of 2-group RCTs with a sample size of at least 100, published in 6 major journals between 1990 and 2010, that evaluated drug treatments for breast, lung, or prostate cancer. PubMed and abstracts of large cancer conferences were searched to identify updated (or earlier) reports of the same trials published up to 2019. Logistic regression was used to identify factors associated with the provision of updated reports. The hazard ratios defining the relative treatment effects for the primary and secondary end points between the initial and updated reports were compared.

Main Outcomes and Measures

Proportion of RCTs whose results are updated, factors associated with updating, and change in hazard ratio for the primary end point between initial and updated reports.

Results

A total of 207 RCTs met the inclusion criteria, and 41 (20%) were found to have updated reports. The factors significantly associated with an update included positive trial results (odds ratio [OR], 8.7 [95% CI, 3.3-23.3]), larger trial size (OR, 1.0006 [95% CI, 1.0000-1.0012]), evaluation of hormonal agents (OR, 5.8 [95% CI, 1.6-21.8]) or targeted agents (OR, 4.3 [95% CI, 1.3-14.6]) compared with chemotherapy, and evaluation of adjuvant therapy rather than therapy for advanced disease (OR, 8.0 [95% CI, 2.9-21.9]). For 31 trials for which initial and updated hazard ratios for the primary end point were available, the median hazard ratio increased from 0.66 (95% CI, 0.22-1.20) to 0.74 (95% CI, 0.32-1.19) (P < .001), indicating a decreased level of effectiveness.

Conclusions and Relevance

Only 20% of reports of phase 3 clinical trials for breast, lung, and prostate cancer were updated. Original reports of such trials are based on relatively few events, and their results are immature; more mature data indicate a decreased level of effect in updated trials. Updated reporting to provide mature, long-term results of clinical trials should be mandated.

Can Oncologists Predict the Efficacy of Treatments in Randomized Trials?

BACKGROUND

Decisions about trial funding, ethical approval, or clinical practice guideline recommendations require expert judgments about the potential efficacy of new treatments. We tested whether individual and aggregated expert opinion of oncologists could predict reliably the efficacy of cancer treatments tested in randomized controlled trials.

MATERIALS AND METHODS

An international sample of 137 oncologists specializing in genitourinary, lung, and colorectal cancer provided forecasts on primary outcome attainment for five active randomized cancer trials within their subspecialty; skill was assessed using Brier scores (BS), which measure the average squared deviation between forecasts and outcomes.

RESULTS

A total of 40% of trials in our sample reported positive primary outcomes. Experts generally anticipated this overall frequency (mean forecast, 34%). Individual experts on average outperformed random predictions (mean BS = 0.29 [95% confidence interval (CI), 0.28-0.33] vs. 0.33) but underperformed prediction algorithms that always guessed 50% (BS = 0.25) or that were trained on base rates (BS = 0.19). Aggregating forecasts improved accuracy (BS = 0.25; 95% CI, 0.16-0.36]). Neither individual experts nor aggregated predictions showed appreciable discrimination between positive and nonpositive trials (area under the curve of a receiver operating characteristic curve, 0.52 and 0.43, respectively).

CONCLUSION

These findings are based on a limited sample of trials. However, they reinforce the importance of basing research and policy decisions on the results of randomized trials rather than expert opinion or low-level evidence.

IMPLICATIONS FOR PRACTICE

Predictions of oncologists, either individually or in the aggregate, did not anticipate reliably outcomes for randomized trials in cancer. These findings suggest that pooled expert opinion about treatment efficacy is no substitute for randomized trials. They also underscore the challenges of using expert opinion to prioritize interventions for clinical trials or to make recommendations in clinical practice guidelines.

Comparative Survival of Asian and White Metastatic Castration-Resistant Prostate Cancer Men Treated With Docetaxel

There are few data regarding disparities in overall survival (OS) between Asian and white men with metastatic castration-resistant prostate cancer (mCRPC). We compared OS of Asian and white mCRPC men treated in phase III clinical trials with docetaxel and prednisone (DP) or a DP-containing regimen. Individual participant data from 8820 men with mCRPC randomly assigned on nine phase III trials to receive DP or a DP-containing regimen were combined. Men enrolled in these trials had a diagnosis of prostate adenocarcinoma. The median overall survival was 18.8 months (95% confidence interval [CI] = 17.4 to 22.1 months) and 21.2 months (95% CI = 20.8 to 21.7 months) for Asian and white men, respectively. The pooled hazard ratio for death for Asian men compared with white men, adjusted for baseline prognostic factors, was 0.95 (95% CI = 0.84 to 1.09), indicating that Asian men were not at increased risk of death. This large analysis showed that Asian men did not have shorter OS duration than white men treated with docetaxel.

Clinical outcomes in men of diverse ethnic backgrounds with metastatic castration-resistant prostate cancer

BACKGROUND

We have shown previously in multivariable analysis that black men had 19% lower risk of death than white men with metastatic castration-resistant prostate cancer (mCRPC) treated with a docetaxel and prednisone (DP)-based regimen. The primary goal of this analysis was to compare progression-free survival (PFS), biochemical PFS, ≥50% decline in prostate-specific antigen (PSA) from baseline and objective response rate (ORR) in white, black and Asian men with mCRPC treated with a DP-based regimen.

PATIENTS AND METHODS

Individual patient data from 8820 mCRPC men randomized on nine phase III trials to a DP-containing regimen were combined. Race used in the analysis was based on self-report. End points were PFS, biochemical PSA, ≥50% decline in PSA from baseline and ORR. The proportional hazards and the logistic regression models were employed to assess the prognostic importance of race in predicting outcomes adjusting for established prognostic factors.

RESULTS

Of 8820 patients, 7528 (85%) were white, 500 (6%) were black, 424 were Asian (5%) and 368 (4%) had race unspecified. Median PFS were 8.3 [95% confidence interval (CI) 8.2-8.5], 8.2 (95% CI 7.4-8.8) and 8.3 (95% CI 7.6-8.8) months in white, black and Asian men, respectively. Median PSA PFS were 9.9 (95% CI 9.7-10.4), 8.5 (95% CI 8.0-10.3) and 11.1 (95% CI 9.9-12.5) months in white, black and Asian men, respectively.

CONCLUSIONS

We observed no differences in clinical outcomes by race and ethnic groups in men with mCRPC enrolled on these phase III clinical trials with DP.

Companion Diagnostics to Identify Biomarkers of Response to Anticancer Drugs Targeting the Proteome

In this issue of Cancer Cell, Pillarsetty and colleagues radiolabel the potential anticancer drug PU-H71 and use it with PET imaging to quantify the epichaperome protein complex in tumors and its inhibition by the drug. They thereby develop a companion diagnostic paradigm of probe-drug pairing to explore therapeutic potential.

The fragility of phase 3 trials supporting FDA-approved anticancer medicines: a retrospective analysis

BACKGROUND

The fragility index of trial results-ie, the minimum number of changes from non-events to events resulting in loss of statistical significance-can provide a measure of confidence that a positive effect reported in a randomised controlled trial is real. We aimed to calculate the fragility index of randomised controlled trials supporting US Food and Drug Administration (FDA)-approved anticancer drugs.

METHODS

This is a retrospective analysis of phase 3, randomised, controlled trials supporting anticancer drugs that were approved by the FDA between Jan 1, 2014, and Dec 31, 2018. Two-arm studies with 1:1 randomisation and significant positive results for a time-to-event outcome were eligible for the fragility index calculation, which involves the iterative addition of an event to the experimental group (defined as the group with the smaller number of events in positive trials) and concomitant subtraction of a non-event from that group, until positive significance (defined as p<0·05 by Fisher's exact test) is lost.

FINDINGS

We identified 36 phase 3 randomised controlled trials, of which 17 (47%) were included in the fragility index analysis. The median fragility index was 2 (IQR 0-27). The fragility index was 2 or less in nine (53%) of 17 trials; for these trials, the fragility index was 1% or less of the total sample size. In five (29%) of 17 trials, the number lost to follow-up was more than the fragility index.

INTERPRETATION

Many phase 3 randomised controlled trials supporting FDA-approved anticancer drugs have a low fragility index, challenging confidence for concluding their superiority over control treatments. Although not a measure of effect, the fragility index might provide an additional means of assessing the robustness of clinical trial data.

FUNDING

None.

A mechanistic cohort study evaluating cognitive impairment in women treated for breast cancer

Some women report cognitive impairment after adjuvant chemotherapy (CTh) for breast cancer. Here we explore cognitive function, and underlying mechanisms with blood tests and functional magnetic resonance imaging (fMRI). Women treated for early breast cancer were recruited to three groups based on self-reported cognitive symptoms (CS) using FACT-Cog scores. CTh + CS+ (n = 44) had received chemotherapy and self-reported cognitive symptoms; CTh + CS- (n = 52) had chemotherapy but did not report cognitive problems; CTh- (n = 30) had not received chemotherapy. Clinical and computer-based neuropsychological tests were performed. Blood tests included 10 cytokines, sex hormones, coagulation factors, and apolipoprotein-E genotype. fMRI (n = 101) was performed while subjects performed an n-back memory task. Participants had median age 50 (range: 29-60) years and were a median of 17 months post-diagnosis. On clinical neuropsychological tests 19% had cognitive impairment using Global Deficit Score, and 36% using International Cancer and Cognition Task Force criteria with no significant differences in cognitive impairment rates between groups. CTh + CS+ had significantly more fatigue, anxiety/depression and poorer quality-of-life than other groups. There was no association between FACT-Cog and neuropsychological scores. There were significant differences in frontal and parietal regions on fMRI scans: CTh- showed hyperactivation compared to chemotherapy-treated groups, CTh + CS+ had more frontal activation than CTh + CS-. Elevated IL-1, IL-2 were associated weakly and IL-8 more strongly with neuropsychological impairment (rho > 0.20). There were no differences in global cognitive impairment between groups. Cognitive symptoms were associated with fatigue and anxiety/depression, but not with objective cognitive impairment. fMRI scans differed among the three groups.

Pantoprazole Affecting Docetaxel Resistance Pathways via Autophagy (PANDORA): Phase II Trial of High Dose Pantoprazole (Autophagy Inhibitor) with Docetaxel in Metastatic Castration-Resistant Prostate Cancer (mCRPC)

BACKGROUND

Enhancing the effectiveness of docetaxel for men with metastatic castration-resistant prostate cancer (mCRPC) is an unmet clinical need. Preclinical studies demonstrated that high-dose pantoprazole can prevent or delay resistance to docetaxel via the inhibition of autophagy in several solid tumor xenografts.

MATERIALS AND METHODS

Men with chemotherapy-naive mCRPC with a prostate-specific antigen (PSA) >10 ng/mL were eligible for enrolment. Men received intravenous pantoprazole (240 mg) prior to docetaxel (75 mg/m²) every 21 days, with continuous prednisone 5 mg twice daily. Primary endpoint was a confirmed ≥50% decline of PSA. The trial used a Simon's two-stage design.

RESULTS

Between November 2012 and March 2015, 21 men with a median age of 70 years (range, 58-81) were treated (median, 6 cycles; range, 2-11). Men had received prior systemic therapies (median, 1; range, 0-3), and 14 had received abiraterone and/or enzalutamide. PSA response rate was 52% (11/21), which did not meet the prespecified criterion (≥13/21 responders) to proceed to stage 2 of the study. At interim analysis with a median follow-up of 17 months, 18 (86%) men were deceased (15 castration-resistant prostate cancer, 2 unknown, 1 radiation complication). Of the men with RECIST measurable disease, the radiographic partial response rate was 31% (4/13). The estimated median overall survival was 15.7 months (95% confidence interval [CI], 9.3-19.6) and median PFS was 5.3 months (95% CI, 2.6-12.9). There were no toxic deaths, and all adverse events were attributed to docetaxel.

CONCLUSION

The combination of docetaxel and pantoprazole was tolerable, but the resultant clinical activity was not sufficient to meet the ambitious predefined target to warrant further testing.

IMPLICATIONS FOR PRACTICE

To date, no docetaxel combination regimen has reported superior efficacy over docetaxel alone in men with metastatic castration-resistant prostate cancer (mCRPC). The PANDORA trial has demonstrated that the combination of high dose pantoprazole with docetaxel is tolerable, but the clinical activity was not sufficient to warrant further testing. The chemotherapy standard of care for men with mCRPC remains docetaxel with prednisone. Future studies of autophagy inhibitors will need to measure autophagy inhibition accurately and determine the degree of autophagy inhibition required to produce a meaningful clinical response.

Overall Survival of Black and White Men With Metastatic Castration-Resistant Prostate Cancer Treated With Docetaxel

PURPOSE

Several studies have reported that among patients with localized prostate cancer, black men have a shorter overall survival (OS) time than white men, but few data exist for men with advanced prostate cancer. The primary goal of this analysis was to compare the OS in black and white men with metastatic castration-resistant prostate cancer (mCRPC) who were treated in phase III clinical trials with docetaxel plus prednisone (DP) or a DP-containing regimen.

METHODS

Individual participant data from 8,820 men with mCRPC randomly assigned in nine phase III trials to DP or a DP-containing regimen were combined. Race was based on self-report. The primary end point was OS. The Cox proportional hazards regression model was used to assess the prognostic importance of race (black v white) adjusted for established risk factors common across the trials (age, prostate-specific antigen, performance status, alkaline phosphatase, hemoglobin, and sites of metastases).

RESULTS

Of 8,820 men, 7,528 (85%) were white, 500 (6%) were black, 424 (5%) were Asian, and 368 (4%) were of unknown race. Black men were younger and had worse performance status, higher testosterone and prostate-specific antigen, and lower hemoglobin than white men. Despite these differences, the median OS was 21.0 months (95% CI, 19.4 to 22.5 months) versus 21.2 months (95% CI, 20.8 to 21.7 months) in black and white men, respectively. The pooled multivariable hazard ratio of 0.81 (95% CI, 0.72 to 0.91) demonstrates that overall, black men have a statistically significant decreased risk of death compared with white men ( P < .001).

CONCLUSION

When adjusted for known prognostic factors, we observed a statistically significant increased OS in black versus white men with mCRPC who were enrolled in these clinical trials. The mechanism for these differences is not known.