Adjuvant Capecitabine for Biliary Cancer and the Importance of Looking Beyond P-Values

This article continues the discussion on the results of the BILCAP trial and advocates for careful examination and consideration of data in its entirety to inform a clinician’s decision.

Analysis of data from the PALOMA-3 trial confirms the efficacy of palbociclib and offers alternatives for novel assessment of clinical trials

PURPOSE

There remains a need for novel therapies for patients with metastatic breast cancer (MBC). We explore the use of a novel biomarker of survival that could potentially expedite the testing of novel therapies.

METHODS

We applied a tumor regression-growth model to radiographic measurement data from 393 women with MBC enrolled in PALOMA-3 examining efficacy of palbociclib in disease that had progressed on previous endocrine therapy. 261 and 132 women were randomized to fulvestrant plus palbociclib or placebo, respectively. We estimated rates of regression (d) and growth (g) of the sensitive and resistant fractions of tumors, respectively. We compared the median g of both arms. We examined the relationship between g and progression-free and overall survival (OS).

RESULTS

As in other tumors, g is a biomarker of OS. In PALOMA-3, we found significant differences in g among patients with tumors sensitive to endocrine therapy but not amongst resistant tumors, emulating clinical trial results. Subgroup analysis found favorable g values in visceral metastases treated with palbociclib. Palbociclib efficacy demonstrated by slower g values was evident early in the trial, twelve weeks after the first 28 patients had been enrolled.

CONCLUSION

Values of g, estimated using data collected while a patient is enrolled in a clinical trial is an excellent biomarker of OS. Our results correlate with the survival outcomes of PALOMA-3 and argue strongly for using g as a clinical trial endpoint to help inform go/no-go decisions, improve trial efficiency, and deliver novel therapies to patients sooner.

Modeling Tumor Growth Using Partly Conditional Survival Models: A Case Study in Colorectal Cancer

PURPOSE

There are multiple approaches to modeling the relationship between longitudinal tumor measurements obtained from serial imaging and overall survival. Many require strong assumptions that are untestable and debatable. We illustrate how to apply a novel, more flexible approach, the partly conditional (PC) survival model, using images acquired during a phase III, randomized clinical trial in colorectal cancer as an example.

METHODS

PC survival approaches were used to model longitudinal volumetric computed tomography data of 1,025 patients in the completed VELOUR trial, which evaluated adding aflibercept to infusional fluorouracil, leucovorin, and irinotecan for treating metastatic colorectal cancer. PC survival modeling is a semiparametric approach to estimating associations of longitudinal measurements with time-to-event outcomes. Overall survival was our outcome. Covariates included baseline tumor burden, change in tumor burden from baseline to each follow-up time, and treatment. Both unstratified and time-stratified models were investigated.

RESULTS

Without making assumptions about the distribution of the tumor growth process, we characterized associations between the change in tumor burden and survival. This change was significantly associated with survival (hazard ratio [HR], 1.04; 95% CI, 1.02 to 1.05; P < .001), suggesting that aflibercept works at least in part by altering the tumor growth trajectory. We also found baseline tumor size prognostic for survival even when accounting for the change in tumor burden over time (HR, 1.02; 95% CI, 1.01 to 1.02; P < .001).

CONCLUSION

The PC modeling approach offers flexible characterization of associations between longitudinal covariates, such as serially assessed tumor burden, and survival time. It can be applied to a variety of data of this nature and used as clinical trials are ongoing to incorporate new disease assessment information as it is accumulated, as indicated by an example from colorectal cancer.

Requirements for Meaningful Progress in the Therapy of Neuroendocrine Cancers

This Viewpoint discusses the role of data interpretation and clinical trial design in improving therapy of neuroendocrine cancers.

Using tumor growth rate to inform treatment efficacy in pancreatic adenocarcinoma: From the metastatic to the neoadjuvant setting

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Background: The development of new treatments in oncology is a long, costly, and, too often, unsuccessful process. Methods for screening agents earlier in development and strategies for conducting smaller randomized controlled trials are needed. Methods: We used a mathematical model of tumor growth kinetics fit to serial radiographic tumor measurements or CA19-9 values to estimate rates of exponential tumor growth [g] and decay [d] during treatment for pancreatic ductal adenocarcinoma (PDAC). Results: We retrospectively collected and analyzed data from 2691 patients with stage III-IV PDAC who were enrolled in five clinical trials or were included in two large real-world data sets from Columbia University Irving Medical Center and Veterans Administration Medical Centers. Using log-rank comparison of Kaplan-Meier plots by quartile of g, we found that in patients with metastatic PDAC g correlates highly with overall (OS) and progression-free survival (PFS) (p<0.001), with slower g associated with improved survival in this population. Pairwise comparisons showed significantly slower median g in the experimental arm versus control arm in the pivotal trials analyzed (p<0.001). At the individual patient level, g was significantly faster for liver metastases as compared to primary pancreatic tumors and g consistently increased towards the end of therapy (often a threefold increase) suggesting development of chemoresistance. In addition to utility in the metastatic setting, a pilot analysis of data from a prospective study of patients treated with gemcitabine + docetaxel + capecitabine (GTX) in the neoadjuvant setting suggests that the emergence of a detectable g during neoadjuvant therapy may portend worse OS following surgery though sample size was small (n=45, median OS with detectable g 13.6 m v 33.1 without detectable g, p =0.35). Conclusions: We applied a tumor growth model to the data of over 2500 patients with PDAC and showed that g is inversely associated with survival in this population. Given the strong association between g and survival, g could be useful in clinical trials as an informative endpoint to expedite the assessment of novel therapies for the treatment of PDAC. Furthermore, g offers valuable patient-level data, including trends in resistance and variations in growth rate by metastatic disease site We plan to evaluate whether the emergence of g during neoadjuvant therapy should be considered a prompt to change treatment regimens.

The genomic landscape of advanced gastrointestinal (GI) neuroendocrine tumors (NET) and carcinomas (NEC)

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Background: The impact of specific genomic alterations in advanced GI neuroendocrine malignancies on prognosis and treatment decisions has not been fully characterized. In this study, we seek to evaluate next-generation sequencing (NGS) panels and corresponding clinical outcomes in patients with metastatic GI NET/NEC. Methods: Patients with GI-NET/NEC were identified from a database of NGS reports performed at the Cleveland Clinic, and clinical variables were extracted by chart review through an IRB-approved protocol. We provide an analysis of this cohort. Results: Of a total n=45 patients, 53% were male. Median age at diagnosis was 60 (range: 35-90 years) and 82% were non-Hispanic white, while 9% were black. There were n=25 GI-NETs, mostly intermediate or high grade (11 G3, 7 G2), and n=20 GI-NECs. There was a balanced distribution of primary sites, including colorectal (27%), pancreas (24%), small intestine (18%), unknown primary (24%) and a single case of biliary primary. High grade GI-NETs and GI-NECs were over-represented in the colorectal primary group vs other sites. (n=10 of 12; p=0.021). The majority of patients (73%) had at least one somatic variant, including 12 patients (27%) with one or more mutations deemed actionable, but only one patient (with MSH2 mutation) has received a mutation-matched drug (pembrolizumab). Some recurrent alterations appeared to co-segregate with aggressive histology (NEC vs NET), including 12 of 13 TP53 mutations (p<0.05 by Fisher Exact Test), 7 of 8 RB1 (p<0.05), and 5 of 6 APC (p=0.074). The most common mutations per person based on primary site is shown. Microsatellite instability high was rare (n=1) and median tumor mutational burden (TMB) was 3/mb, with TMB lower in NETs vs NECs. A number of patients (35%) underwent germline testing, with 6 of 16 having a pathogenic germline variant. Conclusions: As 42% of the 12 patients with actionable mutations were alive at time of analysis, it is possible that additional patients could be treated with mutation-matched therapies. More input will be needed from providers as to the role played by alternative effective treatments and barriers such as insurance coverage and prior authorization to implementing mutation-matched therapies. Given the overall low TMB of GI-NETs, with several tumors having zero or 1 reported mutation on targeted NGS, whole genome sequencing may prove useful. Finally, certain mutations such as RB1 and TP53 were associated with more aggressive histology (i.e. NEC). Lastly, only 9% of our cohort with NGS were black, a significant under-representation based on epidemiological data, which raises concerns about disparate accessibility and barriers to NGS testing. Further studies are needed to address any possible racial disparity.[Table: see text]

Overall survival (OS) in gastrointestinal (GI) neuroendocrine tumors (NETs) based on primary site, stage, and surgery

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Background: There are limited data on the impact of primary site and surgical intervention on long-term outcomes in GI-NETs. We hypothesized that primary site would be associated with differences in stage-specific OS. Methods: In the National Cancer DataBase, using histology codes, we identified 124,081 GI-NETs diagnosed between 2004-2019 in individuals 18 years or older. OS was estimated by the Kaplan-Meier method. Differences in survival based on primary site, stage, and surgical intervention were assessed using a Cox proportional hazards model, accounting for multiple comorbidities, e.g. Charlson-Deyo Comorbidity Index. Results: The most common primary site for GI-NETs was small intestine (33.6%), followed by colon, rectum, pancreas, and stomach comprising 19.8%, 17.5%, 15.5%, and 9.2%, respectively. Patients with stage I-III NETs undergoing surgery had significantly better median OS compared to those without surgery (mOS 197 vs 115 mo., p<0.0001 by log rank test). Patients with stage IV NETs undergoing primary resection also had improved mOS vs those with no surgery (125 vs 54 mo., p<0.0001). For stage I-III patients without surgery, 2-yr and 5-yr survival rates were highest in the rectum and lowest in small intestine ( p<0.0001). Among those with stage I-III with surgery, 2-yr and 5-yr survival rates were also highest in the rectum, and lowest in the biliary system at 89% and 82% ( p<0.0001). In contrast, for stage IV patients without primary resection, 2-yr and 5-yr survival rates were highest among small intestine and lowest in the rectum ( p<0.0001). Among those who had primary tumor resection, 2-yr and 5-yr survival rates were highest in pancreas and lowest in colon at 2 yrs and rectum at 5 yrs ( p<0.0001). Conclusions: Surgical intervention for GI-NETs is associated with improved OS in both localized and stage IV disease, with consistent trends across different primary sites. Primary tumor resection was associated with the largest increase in 5-yr survival for stage IV NETs arising from pancreas and stomach. Patient selection for surgery undoubtedly contributed to the improved OS, but resection of primary tumors in stage IV GI-NETs may have a disease modifying effect. Further study is warranted with more granular data to identify patients with stage IV GI-NETs who may benefit from primary tumor resection.[Table: see text]

Supporting Patients with Cancer after Dobbs v. Jackson Women's Health Organization

In the context of cancer, whether or not to choose pregnancy termination represents a difficult and multifaceted decision. In this editorial, members of The Oncologist editorial team attempt to contextualize the potential implications of the recent Supreme Court decision in Dobbs v. Jackson Women’s Health Organizationfor patients with cancer.

Association of early tumor growth rate and survival outcomes in first-line metastatic non–small cell lung cancer (mNSCLC)

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Background: Tumor growth rates ( g) estimated using imaging measurements, have been associated with overall survival (OS) and progression-free survival (PFS) in patients with mNSCLC, including those treated with first-line immunotherapy (1L IO) or chemotherapy (chemo). Here, we evaluated whether early g estimates within 18 weeks of first treatment dose are associated with survival outcomes for 1L treatment in mNSCLC. Methods: This was a retrospective analysis of data from patients randomized to either nivolumab+ipilimumab (NIVO+IPI) or chemo in CheckMate 227 Part 1 (NCT02477826), or NIVO+IPI+chemo or chemo alone in CheckMate 9LA (NCT03215706). Tumor assessments were performed by blinded independent central review using RECIST v 1.1 at baseline, every 6 weeks for the first 48 weeks and then every 12 weeks until disease progression. The analysis included patients with at least 3 measurable timepoints, including baseline, week 6, week 12, and/or week 18. If a patient did not have a week 18 measurement, the first three measurements alone were used. To derive the median early g, sum of longest diameters (SLD), based on baseline, weeks 6, 12 and/or 18 assessments, and time relative to baseline were fitted to the model defined by sum of exponential growth (g) and decay (d): SLD (t) = exp (–d x t) + exp (g x t) – 1. OS and PFS were estimated using Kaplan-Meier methodology. Results: In the two studies, 865/1166 (75%) of randomized patients in CheckMate 227 Part 1 and 562/719 (78%) in CheckMate 9LA had evaluable tumor growth rate data (Table). The median early g at weeks 12 and 18 was numerically lower for the IO-containing arm vs chemo arm in both studies (Table). Patients with lower growth rate at week 12 or week 18 ( g in first quartile [Q1]) had better OS relative to those with higher rate ( g in fourth quartile [Q4]) across all treatment arms (Table). A similar trend was observed for PFS. Conclusions: Early g estimates based on 2 or 3 post-baseline tumor assessment timepoints were associated with longer-term survival outcomes for 1L treatment of mNSCLC and could discern efficacy outcomes. These findings provide the foundation for further research, which may incorporate volumetric segmentations of measurable lesions and radiomic feature changes to further explore indicators of patient outcomes that could inform future clinical trials and clinical practice.[Table: see text]

A novel analysis of data from the PALOMA-3 trial confirms the efficacy of palbociclib and provides an option for efficacy assessments that could accelerate drug approvals

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Background: Advances in breast cancer (BC) therapy the past few decades have led to higher survival rates. Beginning with palbociclib, cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors have emerged as a treatment option for BC. We analyzed data from PALOMA 3 that could release a biomarker of OS in patients that receive palbociclib. Methods: We estimated concurrent rates of growth ( g) and regression ( d) from the 393 women with advanced BC enrolled in PALOMA-3 who had radiographic tumor measurement data including 261 treated with fulvestrant + palbociclib, and 132 with fulvestrant + placebo. We analyzed data using a model defined as SLD (t) = exp (– d x t) + exp ( g x t) – 1, where SLD = sum of longest diameters and t = time. We examined the relationship between g and overall survival (OS) and compared the median growth rates ( g) of various cohorts. Results: g values associate highly with OS (p<0.0001). Emulating results in the clinical trial, palbociclib slowed the median g values of the entire population and those with sensitivity to previous endocrine therapy but not those deemed resistant. Further cohort analyses found greater benefit with palbociclib in those with visceral metastases, and longer disease-free interval, and benefit independent of ECOG PS, menopausal status, prior lines of therapy, and age. With only the baseline and two additional scans obtained, the median g values of the palbociclib and placebo arms were statistically different: p=0.038 after 28 (19/9) patients and p=0.0043 after 40 (26/14) patients. Conclusions: Estimates of palbociclib’s impact on tumor growth rates ( g) confirm its efficacy in PALOMA 3. Our ability to discern differences in g, a value associated with OS, after only two follow up scans in as few as 28 patients merits considering g an early biomarker of OS benefit that could bring effective drugs to patients as rapidly as possible. [Table: see text]

A Medical Pearl Harbor: Pandemic Uncovers Societal Fissures and Leadership Breaches

The Editors of The Oncologist remark on recent national events and call for new strategies for the New Year.

Novel Tumor Growth Rate Analysis in the Randomized CLARINET Study Establishes the Efficacy of Lanreotide Depot/Autogel 120 mg with Prolonged Administration in Indolent Neuroendocrine Tumors

Introduction

Tumor quantity while receiving cancer therapy is the sum of simultaneous regression of treatment‐sensitive and growth of treatment‐resistant fractions at constant rates. Exponential rate constants for tumor regression/decay (d) and growth (g) can be estimated. Previous studies established g as a biomarker for overall survival; g increases after treatment cessation, can estimate doubling times, and can assess treatment effectiveness in small cohorts by benchmarking to large reference data sets. Using this approach, we analyzed data from the clinical trial CLARINET, evaluating lanreotide depot/autogel 120 mg/4 weeks (LAN) for treatment of neuroendocrine tumors (NETs).

Methods and Materials

Computed tomography imaging data from 97 LAN‐ and 101 placebo‐treated patients from CLARINET were analyzed to estimate g and d.

Results

Data from 92% of LAN‐ and 94% of placebo‐treated patients could be fit to one of the equations to derive g and d (p < .001 in most data sets). LAN‐treated patients demonstrated significantly slower g than placebo recipients (p = .00315), a difference of 389 days in doubling times. No significant difference was observed in d. Over periods of LAN administration up to 700 days, g did not change appreciably. Simulated analysis with g as the endpoint showed a sample size of 48 sufficient to detect a difference in median g with 80% power.

Conclusion

Although treatment of NETs with LAN can affect tumor shrinkage, LAN primarily slows tumor growth rather than accelerates tumor regression. Evidence of LAN efficacy across tumors was identified. The growth‐retarding effect achieved with LAN was sustained for a prolonged period of time.

Implications for Practice

The only curative treatment for neuroendocrine tumors (NETs) is surgical resection; however, because of frequent late diagnosis, this is often impossible. Because of this, treatment of NETs is challenging and often aims to reduce tumor burden and delay progression. A novel method of analysis was used to examine data from the CLARINET trial, confirming lanreotide depot/autogel is effective at slowing tumor growth and extending progression‐free survival. By providing the expected rate and doubling time of tumor growth early in the course of treatment, this method of analysis has the potential to guide physicians in their management of patients with NETs.

Treatment of neuroendocrine tumors is challenging, mainly aiming to reduce tumor burden and delay disease progression. This article reports on the kinetics of tumor growth using a novel method of analysis and data from the CLARINET study.

The rate of tumor growth, g, as a biomarker for overall survival (OS) in prostate cancer (PC) in clinical trials as well as in real-world data from the Veterans Administration Medical Centers (VAMCs)

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Background: Novel assessments of efficacy are needed to improve determination of treatment outcomes in clinical trials and in real-world settings. Methods: Cancer treatments usually lead to concurrent regression and growth of the drug-sensitive and drug-resistant fractions of a tumor, respectively. We have exploited novel methods of analysis that assess these two simultaneous processes and have estimated rates of tumor growth ( g) and regression ( d) in over 30,000 patients (pts) with diverse tumors. Results: In prostate cancer (PC) we have analyzed both clinical trial and real-world data from Veterans. Using clinical trial data from 6819 pts enrolled in 15 treatment arms we have established separately and by combining all the data that g correlates highly (p<0.0001) with overall survival (OS) – slower g associated with better OS. In PC, abiraterone (ABI) and docetaxel (DOC) are superior to placebo, prednisone and mitoxantrone. ABI (median g =0.0017) is superior to DOC ( g=0.0021) in first line (p=0.0013); and ABI in 2nd line ( g=0.0034) is inferior to ABI in 1st line ( g=0.0017; p<0.0001). Finally, using combined clinical trial data as a benchmark we could assess the efficacy of novel therapies in as few as 30-40 patients. Amongst 7457 Veterans, the median g on a taxane ( g=0.0022) was similar to that from clinical trials ( g=0.0012). Although only 258 Veterans received cabazitaxel (CAB), g values for CAB ( g=0.0018) and DOC ( g=0.0023) were indistinguishable (p=0.3) consistent with their identical mechanism of action. Finally, outcomes with DOC in African American (AA) ( g=0.00212) and Caucasian ( g=0.00205) Veterans were indistinguishable (p=0.9) and comparable across all VAMCs. Conclusions: The rate of tumor growth, g, is an excellent biomarker for OS both in clinical trials and in real-world settings. g allows comparisons between trials and for large trial data sets to be used as benchmarks of efficacy. Real-world outcomes in the VAMCs are similar to those in clinical trials. In the egalitarian VAMCs DOC efficacy in PC is comparable in AA and Caucasian Veterans -- indicating inferior outcomes reported in AAs are likely due to differential health care access, not differences in biology.

Role of radiomics to differentiate benign from malignant pheochromocytomas and paragangliomas on contrast enhanced CT scans

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Background: Radiomics features, which are quantitative features generated by computational analysis of routine clinical imaging like CT scans, have been shown to be associated with clinical outcomes and tumor’s behavior in some solid tumors. We compared the radiomic features of malignant and benign pheochromocytomas/paragangliomas (P/P). Methods: Through an IRB approved study at our institution, we identified 20 consecutive patients with P/P and with available contrast-enhanced abdominopelvic CT. A radiologist with experience in oncologic imaging identified and segmented tumors on every slice using a MatLab-based imaging platform. The entire tumor image then underwent computational analysis generating 1160 radiomics features reflecting tumor size, shape, density, textural heterogeneity, and margins. These radiomics features were compared between malignant and benign P/P using Wilcoxon-Rank sum test. Results: Of the twenty patients included in this analysis, there were 6 patients with malignant P/P and 14 patients with benign tumors. Patients had been followed for at least 5 and many for at least 10 years after resection of the tumor. At diagnosis, the mean age of patients with benign and malignant tumors were 51 and 45, respectively. A 60% majority of patients with benign tumors were females while a 77% majority of patients with malignant tumors were male. Benign P/P were significantly different from malignant ones in: tumor intensity textures (spatial correlation [p-value = 0.0010], Laws [p-value = 0.0064], LoG [p-value = 0.0087], and Gabor [p-value = 0.0325]), and tumor local surface shape (Shape Index SI7 [p-value = 0.0325]). Conclusions: This initial analysis sought to discern differences in these rare tumors that might be exploited clinically. The results show that compared to benign tumors, malignant P/P tend to have more heterogenous texture, irregular edges, and less rounded shape on contrast enhanced abdominal CT scan. However, because these radiomics phenotype properties are subtle, they cannot be made reliably in an objective fashion using human visual assessment and thus these radiomics features may have a role as a quantitative imaging biomarker in P/P to predict tumor behavior. The cohort is being expanded and data will be updated at the time of the presentation. With larger numbers, the contribution to the radiomics profile of a SDHx mutation will be explored in greater depth to understand the differential impact of SDHx loss and of evolution into a cancer to the radiomics profiles.

Correlation between innate cytokine levels and progression in men with biochemically recurrent prostate cancer treated with intermittent hormonal therapy

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Background: Suppressive cytokines have the potential to drive prostate cancer progression with consequent decreased survival. Assessing longitudinal cytokine changes may shed light on mechanisms of disease progression, resistance to therapy, and suggest new therapeutic targets. Methods: Thirty-seven men with biochemically recurrent (BCR) prostate cancer who received 6 months of androgen deprivation therapy (ADT) and were monitored until the time of PSA progression (TTPP) were identified from a previously conducted phase III trial (NCT00020085). Serum samples were archived at baseline, three months after administration of ADT, and at TTPP. Cytokine concentrations were quantified using a 36-parameter electrochemiluminescence assay (MesoScale Discovery). Wilcoxon signed rank sum test was used to compare paired observations between time points. Kaplan-Meier analysis was used to calculate progression function (TTPP) dichotomized by above or below the median value of cytokines with Bonferroni adjustment. Pearson’s rank correlation coefficient was used to compare continuous variables. Results: Median TTPP was 399 days (range, 114 - 1641). Median PSA at baseline and progression were 8.5 ng/ml, (range, 1.0 - 76.6) and 5.3 ng/mL (range, 1.2 - 19.4), respectively. Twenty-three patients (62%) achieved undetectable PSA with ADT. TNF-α (P = 0.002), IL-23 (P = 0.002), and IP-10 (P = 0.001) significantly increased from baseline to post ADT. Patients with a detectable PSA after ADT had moderately elevated levels of IL-6 (P = 0.049) and IL-8 (P = 0.013) at PSA progression as compared to those with an undetectable PSA. There was a trend toward shorter TTPP in patients with TNF-α levels above the median (P = 0.042). TNF-α was strongly correlated with IL-23 (r = 0.72, P < 0.001) and IL-8 (r = 0.59, P < 0.001) from baseline to after ADT and to PSA progression. NLR correlated strongly with IL-27 (r = 0.57, P < 0.001) and MIP-3α (r = 0.56, P < 0.001). Conclusions: Cytokines associated with the innate immune response were associated with an unfavorable clinical outcome in early prostate cancer. These data suggest cytokine blockade combined with ADT may warrant future investigation.

Effect of metformin chemoprevention on metabolomics profiles in Li-Fraumeni Syndrome (LFS)

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Background: LFS is a highly-penetrant, autosomal dominant, cancer predisposition disorder characterized by early onset cancer; germline mutations in TP53are present in 70% of LFS. We previously observed metformin inhibition on mitochondrial function in LFS patients. Metformin may reduce TCA cycle and glycolytic intermediates during cellular transformation, indicating inhibition of complex I of the mitochondria. To further explore this, we performed untargeted metabolomics profiling on stored serum of study participants. To our knowledge, there are no previous studies of metabolomics profiling in LFS patients treated with metformin. Methods: Adult LFS patients (≥18 years old) were enrolled for 20 weeks. Metformin was initiated at 500 mg per day and increased in 500 mg dose increments every two weeks to a maintenance dose of 2000 mg of metformin. Patients were taken off metformin for the last six weeks of the study (week 20). Global biochemical profiles were determined in human serum samples collected in 21 patients, each providing one sample at baseline, week 14 (on 2000 mg metformin) and week 20 (off metformin). Metabolomics analyses were performed by Metabolon, Inc. Results: Treatment with metformin induced a strong metabolic signature of increased fatty acid beta-oxidation in LFS patients. Acylcarnitines, long chain fatty acids, and 3-hydroxy fatty acids were significantly elevated following metformin treatment. TCA cycle intermediates, aconitate, malate, and fumarate were also increased as were levels of ketone body 3-hydroxybutyrate (BHBA)indicating robust β-oxidation, presumably to support increased energy production via the TCA cycle. Clearance of metformin results in normalization of levels to comparable baseline values, indicating a causal role of metformin in these changes. Conclusions: Global metabolomics profiling suggests an increase in TCA cycle intermediates and a strong signature of fatty acid oxidation with metformin treatment in LFS, suggesting metformin effect on the mitochondria and TCA cycle is more dynamic than previously shown. LFS patients may have distinct metabolic profiles which may be altered by treatment with metformin. Funding: ASCO Young Investigator’s Award 2016. Clinical trial information: NCT01981525.

SDHB-related pheochromocytoma and paraganglioma penetrance and genotype-phenotype correlations

PURPOSE

Succinate dehydrogenase subunit B (SDHB) gene mutations are associated with an aggressive clinical disease course of pheochromocytoma/paraganglioma (PHEO/PGL). Limited information is available concerning PHEO/PGL penetrance among SDHB mutation carriers with regards to primary tumor location, specific mutation type, and gender. We assessed PHEO/PGL penetrance in SDHB mutation carriers and described the clinical presentation and disease course.

METHODS

Asymptomatic relatives (N = 611) of 103 index patients were tested for SDHB mutations. Mutation carriers (N = 328) were offered PHEO/PGL screening, of which 241 participated and were included in penetrance analysis. For additional disease outcome analysis, the 103 index patients and 40 screened individuals who developed PHEO/PGL were included. Clinical data were collected between October 2004 and June 2016.

RESULTS

Forty (16.60%) of the 241 screened individuals developed PHEO/PGL during the study. The penetrance estimate in this population was 49.80% (95% CI 29-74.9) at 85 years. A significantly higher age-related penetrance of disease was observed in males compared to females, with 50% penetrance achieved at age 74 vs. not reached. Age-related penetrance analysis demonstrated 4 mutations (Ile127Ser, IVS1+1G>T, Exon 1 deletion, Arg90X) presenting with a slower rate of disease development (50% penetrance ages, respectively: not achieved, 70, 63, 61 years) compared to Arg46X and Val140Phe mutations (50% penetrance at 38 years).

CONCLUSIONS

Here, we found a higher estimated penetrance compared to several other studies, and a striking difference in age-related penetrance between male and female SDHB mutation carriers with no association between mutation and gender or tumor location.

Inhibiting mitochondrial respiration prevents cancer in a mouse model of Li-Fraumeni syndrome

Li-Fraumeni syndrome (LFS) is a cancer predisposition disorder caused by germline mutations in TP53 that can lead to increased mitochondrial metabolism in patients. However, the implications of altered mitochondrial function for tumorigenesis in LFS are unclear. Here, we have reported that genetic or pharmacologic disruption of mitochondrial respiration improves cancer-free survival in a mouse model of LFS that expresses mutant p53. Mechanistically, inhibition of mitochondrial function increased autophagy and decreased the aberrant proliferation signaling caused by mutant p53. In a pilot study, LFS patients treated with metformin exhibited decreases in mitochondrial activity concomitant with activation of antiproliferation signaling, thus reproducing the effects of disrupting mitochondrial function observed in LFS mice. These observations indicate that a commonly prescribed diabetic medicine can restrain mitochondrial metabolism and tumorigenesis in an LFS model, supporting its further consideration for cancer prevention in LFS patients.

High-Dose Sirolimus and Immune-Selective Pentostatin plus Cyclophosphamide Conditioning Yields Stable Mixed Chimerism and Insufficient Graft-versus-Tumor Responses

PURPOSE

We hypothesized that lymphoid-selective host conditioning and subsequent adoptive transfer of sirolimus-resistant allogeneic T cells (T-Rapa), when combined with high-dose sirolimus drug therapy in vivo, would safely achieve antitumor effects while avoiding GVHD.

EXPERIMENTAL DESIGN

Patients (n = 10) with metastatic renal cell carcinoma (RCC) were accrued because this disease is relatively refractory to high-dose conditioning yet may respond to high-dose sirolimus. A 21-day outpatient regimen of weekly pentostatin (P; 4 mg/m(2)/dose) combined with daily, dose-adjusted cyclophosphamide (C; ≤200 mg/d) was designed to deplete and suppress host T cells. After PC conditioning, patients received matched sibling, T-cell-replete peripheral blood stem cell allografts, and high-dose sirolimus (serum trough target, 20-30 ng/mL). To augment graft-versus-tumor (GVT) effects, multiple T-Rapa donor lymphocyte infusions (DLI) were administered (days 0, 14, and 45 posttransplant), and sirolimus was discontinued early (day 60 posttransplant).

RESULTS

PC conditioning depleted host T cells without neutropenia or infection and facilitated donor engraftment (10 of 10 cases). High-dose sirolimus therapy inhibited multiple T-Rapa DLI, as evidenced by stable mixed donor/host chimerism. No antitumor responses were detected by RECIST criteria and no significant classical acute GVHD was observed.

CONCLUSIONS

Immune-selective PC conditioning represents a new approach to safely achieve alloengraftment without neutropenia. However, allogeneic T cells generated ex vivo in sirolimus are not resistant to the tolerance-inducing effects of in vivo sirolimus drug therapy, thereby cautioning against use of this intervention in patients with refractory cancer.

Redistribution, hyperproliferation, activation of natural killer cells and CD8 T cells, and cytokine production during first-in-human clinical trial of recombinant human interleukin-15 in patients with cancer

PURPOSE

Interleukin-15 (IL-15) has significant potential in cancer immunotherapy as an activator of antitumor CD8 T and natural killer (NK) cells. The primary objectives of this trial were to determine safety, adverse event profile, dose-limiting toxicity, and maximum-tolerated dose of recombinant human IL-15 (rhIL-15) administered as a daily intravenous bolus infusion for 12 consecutive days in patients with metastatic malignancy.

PATIENTS AND METHODS

We performed a first in-human trial of Escherichia coli-produced rhIL-15. Bolus infusions of 3.0, 1.0, and 0.3 μg/kg per day of IL-15 were administered for 12 consecutive days to patients with metastatic malignant melanoma or metastatic renal cell cancer.

RESULTS

Flow cytometry of peripheral blood lymphocytes revealed dramatic efflux of NK and memory CD8 T cells from the circulating blood within minutes of IL-15 administration, followed by influx and hyperproliferation yielding 10-fold expansions of NK cells that ultimately returned to baseline. Up to 50-fold increases of serum levels of multiple inflammatory cytokines were observed. Dose-limiting toxicities observed in patients receiving 3.0 and 1.0 μg/kg per day were grade 3 hypotension, thrombocytopenia, and elevations of ALT and AST, resulting in 0.3 μg/kg per day being determined the maximum-tolerated dose. Indications of activity included clearance of lung lesions in two patients.

CONCLUSION

IL-15 could be safely administered to patients with metastatic malignancy. IL-15 administration markedly altered homeostasis of lymphocyte subsets in blood, with NK cells and γδ cells most dramatically affected, followed by CD8 memory T cells. To reduce toxicity and increase efficacy, alternative dosing strategies have been initiated, including continuous intravenous infusions and subcutaneous IL-15 administration.

External beam radiation therapy in treatment of malignant pheochromocytoma and paraganglioma

Purpose: Pheochromocytomas (PCCs) are neuroendocrine tumors arising from the adrenal medulla or as paraganglioma (PGL) from extra-adrenal sites. While usually benign, a small fraction is malignant. Multi-modality therapy is used in treating malignant disease; however, little data exist on the role of external beam radiation therapy (EBRT). In this retrospective review, we assessed response to EBRT in malignant PCCs or PGLs.

Methods and Materials: Records of patients treated at the National Institutes of Health who received EBRT between 1990 and 2012 were studied. Patients were assessed for symptomatic control, biochemical response, local and distant control by response evaluation criteria in solid tumors v1.1 or stable disease on imaging reports, toxicity by radiation therapy oncology group (RTOG) criteria, and survival.

Results: There were 24 patients treated who received EBRT to lesions of the abdomen (n = 3), central nervous system (n = 4), and bone (n = 40). Lesions were treated with 3D conformal EBRT to a mean dose of 31.8 Gy in 3.3 Gy fractions, or fractionated stereotactic radiosurgery to 21.9 Gy in 13.6 Gy fractions. Patients experienced acute (n = 15) and late (n = 2) RTOG toxicities; no patient experienced acute toxicity ≥4 or late toxicity ≥2. Symptomatic control was achieved in 81.1% of lesions. Stable radiographic response was achieved in 86.7% of lesions with progression in 13%. Distant progression was observed overall in 75% of patients and average survival was 52.4 months.

Conclusion: Malignant PCC and PGL often do not respond well to current systemic therapies. In these cases, EBRT can be considered in patients with symptomatic, localized disease progression.

Phase II clinical trial of bevacizumab plus ixabepilone in renal cell carcinoma

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Background: Metastatic renal cell carcinoma (mRCC) remains incurable. Seven targeted agents are approved for mRCC, five targeting VEGFR and two m-TOR inhibitors. Most approvals have been based on improvements in progression free survival (PFS). Preclinical data indicates synergism of ixabepilone and bevacizumab. Methods: Patients with histologically confirmed mRCC with at least one previous therapy received ixabepilone [6mg/m2/d X 5d] plus bevacizumab [15 mg/kg] every 21 days. The primary endpoint was PFS by RECIST. Secondary endpoints were response rate, overall survival, and safety. In addition to “conventional” efficacy assessments, we calculated the growth rate constant as a measure of efficacy. Results: Thirteen patients have been enrolled. The median number of prior therapies was two (range 1-5). Nine (69%) have stable disease as best response with two (15%) partial responses. Median time to progression (TTP) was 6.39 months. The growth rate constant (g) was 0.0021/day and the regression rate constant (d) was 0.0032/day. Six patients discontinued treatment due to progression; one patient died. Principal toxicities including hypertension, fatigue, anemia and thrombocytopenia led two patients to discontinue therapy. One continues on study after 25 cycles. Accrual continues. Conclusions: Ixabepilone plus bevacizumab has activity in mRCC. A median TTP of 6.39 months compares favorably with 3.9-4.8 months for approved second line therapies. The calculated growth rate of 0.0021/day in this refractory population is indistinguishable from a value of 0.0022/day with single agent bevacizumab in treatment-naive mRCC. However, we cannot discern if this reflects bevacizumab activity even in refractory disease or a beneficial ixabepilone effect. Clinical trial information: NCT00923130.

Relationship of the emergence of KRAS mutations and resistance to panitumumab in second-line treatment of colorectal cancer (CRC)

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Background: Multiple analyses have concluded anti-EGFR antibodies are detrimental to a majority of patients (pts) whose CRCs harbor mutant KRAS. While panitumumab may benefit some pts with tumors harboring WT KRAS, in the majority the added benefit is small and transient. Recent studies have claimed emergence of KRAS mutations mediates acquired resistance to EGFR inhibitors. Methods: We analyzed published and unpublished data to assess this possibility, calculating growth and regression rate constants and estimating doubling times of CRC. Results: Amongst 24 pts with CRC whose tumors were initially KRAS WT, circulating mutant KRAS transcripts were detected in 9 treated in second line with panitumumab plus chemotherapy [Diaz et al, Nature 2012]. The growth rate of tumor in the 9 pts with circulating MT KRAS was 0.0019 days-1. This value is statistically indistinguishable [p = .2439] from the growth rate of 0.0021 days-1 calculated for tumors in 15 pts with no detectable circulating MT KRAS transcripts. Both values were also statistically indistinguishable [p = .3055 for MT KRAS; p = .7688 for WT KRAS] from the growth rate [0.002 days-1] of tumors in a cohort treated in second line with the same chemotherapy without an EGFR inhibitor. Similar results were observed when growth rates were calculated using CEA values [WT, 0.00087 days-1; MT, 0.0024 days-1; p = .1265] and similar regression rate constants were also calculated [WT, 0.0114 days-1; MT, 0.0117 days-1; p = .858]. Furthermore, in pts with detectable serum MT KRAS transcripts the growth rate remained constant even as MT KRAS transcripts appeared to increase. The growth rates allowed us to estimate tumor doubling times of 110 to 124 days in these pts receiving second line therapies, consistent with clinical data for disease progression in second line; and similar to the estimated doubling time of 116 days in the cohort that did not receive panitumumab. Conclusions: Resistance to panitumumab in tumors harboring WT KRAS cannot be explained by overgrowth of cells with MT KRAS. Other mechanisms must be sought to explain the limited efficacy of panitumumab. The data suggest such mechanism(s) are inherent and likely present in the majority of cells.

Phase I trial of belinostat in combination with cisplatin (Cis) and etoposide (Etop)

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Background: Histone deacetylase inhibitors (HDIs) are epigenetic therapies in development. To exploit the unique activity in impairing DNA repair, HDIs have been combined with chemotherapy. Belinostat is a potent HDI combined with Cis and Etop based on enhanced DNA damage and apoptosis in small cell lung cancer (SCLC) cells. Methods: Patients with relapsed/refractory cancer or previously untreated advanced stage SCLC were eligible. Belinostat was administered by continuous infusion (CIV) over 48h, from 400 mg/m2/24h, in cohorts of 3. Cis was administered on day 1 and Etop daily X3. Belinostat pharmacokinetics (PK) and several pharmacodynamic (PD) measures were assessed, including lysine acetylation in peripheral blood mononuclear cells (PBMCs) and γH2Ax staining in PBMCs and in hair follicles. Results: Five dose levels were explored in 20 patients with solid tumors, including 5 patients with SCLC, two who had no prior therapy. At the first dose level, dose-limiting toxicities (DLT) of gr 4 ANC in 1, and gr 3 HTN in 1 were observed. Cis and Etop were reduced to 60 mg/m2 and 80 mg/m2, respectively, and the dose level repeated without DLT. At the next dose level, 800 mg/m2/24h belinostat, grade 3 HTN and grade 4 pneumonitis were observed. At the MTD of 600 mg/m2/24h belinostat, DLT was seen in 1 of 6 pts; however, all 6 pts required later dose reductions. We thus considered 500 mg/m2/24h in combination with Cis and Etop to be the recommended Phase II dose; confirmation ongoing. PKs show belinostat levels at 1 uM over the 48h infusion, decreasing rapidly to the 60h timepoint. In total 11 pts, 3 with SCLC, completed 6 cycles. PR was seen in 6 pts (3 with SCLC). PD studies confirmed γH2AX staining in PBMCs and hair follicles, peaking at 36h and 60h, respectively. Tubulin and lysine acetylation (Ac-K) in PBMCs peaked at 36h; Ac-K recovered more rapidly than tubulin, mirroring γH2AX. Conclusions: The MTD of belinostat over 48h by CIV was 600 mg/m2/24h, in combination with Cis 60 mg/m2 on day 1 and Etop 80 mg/m2 on days 1 - 3. PD endpoints indicate that belinostat is active in promoting both acetylation and DNA damage. The HDI combined with chemotherapy requires dose reduction and likely represents an on-target increase in DNA damage. Clinical trial information: NCT00926640.

Targeted agents (TA) for advanced solid tumors (AST): What is the likelihood of being helped or harmed (LHH)? Assessing the clinical impact of therapies with FDA/EMEA approval

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Background: Health care agencies adopt systems to inform patients and health care providers about relative risks and benefits using Evidence Based Medicine (EBM) measures, such as the number of patients needed to be treated/harmed (NNT/NNH), and LHH. This analysis was undertaken to provide an overview of the LHH provided by TA for AST. Methods: Randomized clinical trials (RCTs) supporting FDA/EMEA approval for TA (tyrosine kinase inhibitors, TKI, and monoclonal antibodies, MoAb) were evaluated provided efficacy (PFS, OS), and safety (grade 3-4 specific toxicities) data were available. NNT/NNH were calculated from absolute differences determined for PFS/OS rates (reported/extracted from Kaplan-Meier (K-M) curves and for the worst drug-specific toxicities. LHH was calculated for PFS or OS. A sensitivity analysis according to the randomized comparison (placebo controlled [P] or accepted standard [STD] vs add-on) was performed. Results: Thirty-five separate approvals were identified (23/12 for PFS/OS advantage, respectively). Results are shown in the Table. Hypertension and rash were most frequent drug specific toxicities. LHH >1 may be interpreted as "number of times drug is more likely to provide a benefit than to harm." Conclusions: Despite limitations (estimation from K-M curves and differences in drug toxicities) the data demonstrate the greatest benefit as measured by LHH was achieved with TKI against P or STD with PFS as the endpoint. Marginal benefits were achieved in the majority of OS analyses, and with add-on design. The latter may reflect difficulty of the OS endpoint, marginal benefits of the TA added (bevacizumab and cetuximab) or may indicate TAs combine only poorly with conventional regimens. These data should be complemented with a cost-analysis and put in the context of the general health care system. [Table: see text]

Phase I/II trial of crolibulin and cisplatin in solid tumors with a focus on anaplastic thyroid cancer: Phase I results

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Background: Anaplastic thyroid cancer (ATC) is one of the most aggressive of all solid tumors, with a median survival of 3-5 months. Chemotherapy has not impacted local control or survival. Crolibulin (CRO) is a microtubule destabilizing agent that disrupts vascular endothelial cells, and in turn, blood flow to the tumor. Preclinical studies showed synergism with cisplatin (CIS). The phase I portion of this phase I/II study, designed to assess the safety and tolerance of CRO and CIS in patients with solid tumors, has completed accrual. Methods: Patients with advanced solid tumors, ECOG ≤ 1, and adequate organ function were treated on a dose escalation schema with CIS (75-100 mg/m2) IV day 1 and CRO (13-20 mg/m2) IV days 1, 2, 3 (21-day cycles). CIS and CRO were continued until unacceptable toxicity or progressive disease (PD), with an option to continue CRO alone if toxicity was CIS-related. Results: Between Jan 2011 and Jan 2013, 21 patients were enrolled and assigned CIS/CRO (mg/m2) at 75/13 (6), 75/20 (3), and 100/20 (12). Diagnoses were as follows: ATC (16), urothelial carcinoma (2), prostate carcinoma (2) and mesothelioma (1). Patients received a median of 2 cycles of CIS/CRO (range: 1-6). Presently, four remain on CIS/CRO and one on CRO alone. The most common grade (G) 3 toxicities were: lymphopenia (33%), hyponatremia (29%), anemia (19%), hypertension during infusion (14%), and hypophosphatemia (9%). There were two G4 toxicities: elevated lipase and thrombocytopenia; and one G5 toxicity of laryngeal hemorrhage related to tumor erosion. There were two dose-limiting toxicities: G3 pancreatitis at dose level (DL) 1 and laryngeal hemorrhage at DL3. Eight ATC patients were treated at DL3. Of these, one (13%) had RECIST 1.1 complete response (CR) and one (13%) had stable disease (SD). Three (38%) had PD, and three are not yet evaluable. The CR has been on study for > 12 months and remains on CRO alone. Conclusions: CIS plus CRO deserves further evaluation as a regimen for ATC. The MTD of CIS/CRO is 100 mg/m2 IV day 1 and 20mg/m2 IV days 1, 2, 3 every 21 days. This combination is well tolerated, with toxicity primarily related to CIS. The phase II portion of this trial will compare CIS/CRO versus CIS in ATC patients. Clinical trial information: NCT01240590.

A phase II study of a yeast-based therapeutic cancer vaccine, GI-6207, targeting CEA in patients with minimally symptomatic, metastatic medullary thyroid cancer

TPS3127

Background: Saccharomyces cerevisiae has been genetically modified to express CEA protein and developed under a CRADA with GlobeImmune/NCI as a heat-killed immune-stimulating, therapeutic cancer vaccine (GI-6207). A phase I study with GI-6207 demonstrated safety, biomarker stabilization and enhanced immune response in some patients. CEA is over-expressed in multiple malignancies, including medullary thyroid cancer (MTC). Two therapies recently approved by the FDA for metastatic MTC (vandetanib, cabozantinib) come with toxicity and should be reserved for symptomatic/progressive disease. However, a large population of asymptomatic MTC patients has small tumor burden and/or disease that is more indolent. The standard management of these patients is observation. Preliminary data suggest that tumor growth measured by the rate of CEA and calcitonin increase can be quantified in a 3-6 months. Retrospective data from prostate cancer studies suggest vaccines can alter growth rates within 3-4 months. We hypothesize that GI-6207 can alter tumor growth rates in MTC and impact long-term outcome. Methods: A phase II study will evaluate the effect of GI-6207 onthe rates ofincrease in calcitonin in metastatic MTC. 34 patients with minimally symptomatic, radiographically evaluable, metastatic MTC will be randomized 1:1. Arm A will receive vaccine for a year from the time of enrollment. Arm B will receive vaccine after 6 months of surveillance. GI-6207 will be administered subcutaneously at 4 sites (10 yeast units/site), every 2 weeks for 3 months, then monthly up to 1 year. The primary endpoint will compare the effect of GI-6207 on calcitonin kinetics between the vaccine and surveillance arms in the first 6 months. Secondary endpoints include immunologic responses (including antigen-specific T cell responses), objective responses, time to progression, and changes in CEA kinetics. If this trial can prospectively demonstrate that vaccines can alter tumor growth rates, and if such changes are associated with clinical outcomes, then changes in tumor growth rates may become a clinical metric to evaluate vaccine efficacy in MTC and other populations.

Two decades of therapy in metastatic colorectal cancer (mCRC): An analysis to discern the contribution and progress made by chemotherapy

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Background: The past 20 years have seen progress in mCRC with more effective agents and better medical, surgical and supportive care. Methods: Systematic review of 101 phase III and large phase II trials in mCRC to quantify benefit over time with first-line and subsequent therapies. Outcomes in the experimental (EA) and control arms (CA) included progression-free survival (PFS), overall response rate (ORR), stable disease (SD), and overall survival (OS). Data were analyzed according to dates of publication and median enrollment. Results: Significant outcomes are reported; most had R2 values > 0.6. OS of EA improved 0.83 mos/yr. Importantly OS of CA improved 0.58 mos/yr likely reflecting subsequent use of experimental regimens in CA and improvement in mCRC care over time. Chemotherapy has contributed only partly to gains in OS since (1) only modest improvements of PFS (0.33 [EA] and 0.26 [CA] mos/yr) and we have shown OS gains are proportional to PFS gains indicating other factors are as or more important than chemotherapy; and (2) lack of OS improvement in 14 second/subsequent line trials. Furthermore, to assess the contribution of each drug/drug class to improvement in OS we performed linear regression with OS the dependent variable versus time publication. We found oxaliplatin, irinotecan and bevacizumab have contributed to progress; but not cetuximab/panitumumab likely explained by inclusion of pts with tumors harboring mutant ras in studies. Not surprisingly, capecitabine in place of 5-fluorouracil had no impact on progress made. As expected PFS correlates highly with OS, but importantly ORR had very high correlations with both PFS and OS. SD was an “adverse” outcome, OS decreasing as SD rates increase. Conclusions: OS of mCRC patients has improved gradually over the past two decades, with gains from chemotherapy and importantly gains from other factors, including lead-time bias, better loco-regional approaches and supportive care. Gains from first line therapies have been modest but consistent; gains from second line therapies have been disappointing. We believe future progress will be more fruitful if emphasis is given to improving second line therapies.

A method for assessing tumor response to therapy and more precisely guiding treatment decisions so as to improve survival

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Background: The response of tumors to chemotherapy is monitored using imaging data or tumor markers and this quantitative data provides a rich source for an objective response assessment and treatment decisions. Responses are usually assessed as categorical variables based on percentage increase or decrease in tumor size. Methods: We have developed mathematical equations that describe efficacy as a continuous variable, enabling the extraction of the appropriate rate constants for tumor growth and regression (decay), designated g and d, respectively. Both are used to describe the rates of tumor growth and regression for the fraction of tumor that is growing despite treatment and the fraction dying as a result of therapy, respectively. Results: Using data from randomized phase III trials in kidney and breast cancer, multiple myeloma, and medullary thyroid carcinoma; as well as phase II trials in prostate cancer we have shown that: (1) values of g but not those of d are strongly correlated (negatively) with patient survival; (2) g can be discerned early in treatment, before growth is demonstrated clinically, providing an early efficacy measure; (3) g typically does not change over time, even over years, suggesting resistance is intrinsic and predictable and does not worsen over time; (4) effective therapies both increase d, and reduce g; and (5) in every cancer studied, the evidence suggests tumor growth reverts to its pre-treatment rate when chemotherapy is discontinued. Conclusions: The observation that g remains stable allows one to predict the most likely outcome of continued therapy. The evidence indicates that the increase in g occurring after treatment discontinuation is due to a resumption of a pre-treatment growth rate and not a change in biology. Our hypothesis is that if a favorable growth rate that slows tumor growth can be identified, survival might be improved if therapies that achieve this favorable growth rate are continued despite crossing conventional disease progression boundaries. We plan a prospective test of this model to provide a more informed decision and better survival outcome by maximizing the benefit obtained from approved therapies.

Difference between duration of treatment (DOT) and progression-free survival (PFS) as a marker of unbalanced censoring

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Background: In the conduct of randomized trials Kaplan and Meier envisioned rates of censoring as similar between arms, providing accurate assessment of clinical trial results. Censoring is used when patients withdraw consent, leave study due to toxicity, or reach data cut-off without disease progression or death. Censoring can lead to erroneous conclusions as it can be either beneficial or detrimental to the arm under study. Such censoring can also explain how a statistically valid difference in PFS “disappears” when overall survival (OS) is examined. We hypothesized that censoring, especially that due to toxicity, would lead to a discrepancy between DOT and PFS since two different patient populations would be scored. Methods: We reviewed all phase III randomized studies of drugs approved by FDA since 2005 for pts with metastatic solid tumors, looking for DOT and PFS. We used standard statistical analyses using SAS. Results: We identified 55 Phase III studies conducted with abiraterone, axitinib, bevacizumab, cabazitaxel, cetuximab, eribulin, erlotinib, everolimus, ipilimumab, ixabepilone, lapatinib, panitumumab, pazopanib, sorafenib, sunitinib, temsirolimus and vandetinib. DOT was not provided in 27%. Forty-four comparisons (88 arms) were included in the analysis. The median PFS, DOT, delta PFS (difference in PFS between experimental and control arms) and delta DOT were: 161, 126, 51 and 36 days, respectively. The slopes of PFS vs DOT and delta PFS vs delta DOT were 1.16 and 1.03, respectively close to the ideal of 1.0. Five trials fell above the 90% CI boundary with delta PFS/delta DOT of 3 to 36, including two everolimus studies (PNET and breast cancer) two sunitinb studies (RCC and PNET) and one bevacizumab study (E2100, breast cancer). Conclusions: PFS and DOT as well as delta PFS and delta DOT should be concordant. The most likely explanation for a discordance between these values is toxicity-driven censoring and its occurrence raises concerns regarding the degree of efficacy. A greater utilization of “Time to Treatment Failure”, an endpoint that includes toxicity in its definition would be valuable in oncology trials, particularly those with high levels of toxicities.

Inhibitors targeting mitosis: tales of how great drugs against a promising target were brought down by a flawed rationale

Although they have been advocated with an understandable enthusiasm, mitosis-specific agents such as inhibitors of mitotic kinases and kinesin spindle protein have not been successful clinically. These drugs were developed as agents that would build on the success of microtubule-targeting agents while avoiding the neurotoxicity that encumbers drugs such as taxanes and vinca alkaloids. The rationale for using mitosis-specific agents was based on the thesis that the clinical efficacy of microtubule-targeting agents could be ascribed to the induction of mitotic arrest. However, the latter concept, which has long been accepted as dogma, is likely important only in cell culture and rapidly growing preclinical models, and irrelevant in patient tumors, where interference with intracellular trafficking on microtubules is likely the principal mechanism of action. Here we review the preclinical and clinical data for a diverse group of inhibitors that target mitosis and identify the reasons why these highly specific, myelosuppressive compounds have failed to deliver on their promise.

Analyzing the pivotal trial that compared sunitinib and IFN-α in renal cell carcinoma, using a method that assesses tumor regression and growth

PURPOSE

We applied a method that analyzes tumor response, quantifying the rates of tumor growth (g) and regression (d), using tumor measurements obtained while patients receive therapy. We used data from the phase III trial comparing sunitinib and IFN-α in metastatic renal cell carcinoma (mRCC) patients.

METHODS

The analysis used an equation that extracts d and g.

RESULTS

For sunitinib, overall survival (OS) was strongly correlated with log g (Rsq = 0.44, P < 0.0001); much less with log d (Rsq = 0.04; P = 0.0002). The median g of tumors in these patients (0.00082 per days; log g = -3.09) was about half that (P < 0.001) of tumors in patients receiving IFN-α (0.0015 per day; log g = -2.81). With IFN-α, the OS/log g correlation (Rsq = 0.14) was weaker. Values of g from measurements obtained by study investigators or central review were highly correlated (Rsq = 0.80). No advantage resulted in including data from central review in regressions. Furthermore, g can be estimated accurately four months before treatment discontinuation. Extrapolating g in a model that incorporates survival generates the hypothesis that g increased after discontinuation of sunitinib but did not accelerate.

CONCLUSIONS

In patients with mRCC, sunitinib reduced tumor growth rate, g, more than did IFN-α. Correlating g with OS confirms earlier analyses suggesting g may be an important clinical trial endpoint, to be explored prospectively and in individual patients.

Twenty years of chemotherapy for colorectal cancer (CRC): Progress made, insights gleaned

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Background: The past 20 years have seen progress in CRC therapy with more effective agents and better medical, surgical and supportive care.

Methods: We conducted a systematic review of 101 phase III and large phase II trials in CRC to quantify benefit over time with first-line and subsequent therapies. Outcomes examined in the experimental (EA) and control arms (CA) included progression-free survival (PFS), overall response rate (ORR), stable disease (SD), overall survival (OS) and post-treatment survival (PTS). Data were analyzed according to dates of publication and median enrollment.

Results: Significant outcomes are reported; most had R2 values > 0.6. OS of EA improved 0.83 mos/yr. Importantly the OS of CA improved 0.58 mos/yr likely reflecting use of experimental therapies in CA in subsequent studies and improvement in CRC care over time as suggested by: (1) modest improvements of PFS: 0.33 [EA] and 0.26 [CA] mos/yr; (2) PTS gains of 0.48 [EA] and 0.29 [CA] mos/yr, accounting for majority of OS gains; and (3) lack of OS improvement in 14 second/subsequent line trials. Using logistic regression to examine all drugs as class predictors of increasing OS, oxaliplatin [OX], bevacizumab [BEV], and irinotecan [IRI] were significant in the EA, but only OX and BEV were significant in the CA. Capecitabine [CAP] and cetuximab/panitumumab [CET/PAN] were not significant in EA or CA, with CAP odds ratio towards null and CET/PAN odds ratio away from null. The lack of IRI effect in CA concurs with observation that only IRI regimens had worse OS in CA compared with EA. The CET/PAN results likely reflect lack of efficacy/harm in patients with WT KRAS tumors. As expected PFS and PTS correlate highly with OS, but importantly ORR had very high correlations with both PFS and OS. SD emerged as an “adverse” outcome, OS decreasing as SD rates increase.

Conclusions: OS of CRC patients has improved gradually over past two decades, with gains from chemotherapy but also other factors, such as lead-time bias, more loco-regional approaches and improved supportive care. IRI performed better in EA than in CA. CET/PAN had negative effects in the entire population. In CRC, ORR correlates highly with OS, while SD portends a poor outcome.

Radiofrequency ablation of metastatic pheochromocytoma

In the present report on the preliminary safety and effectiveness of radiofrequency (RF) ablation for pheochromocytoma metastases, seven metastases were treated in six patients (mean size, 3.4 cm; range, 2.2-6 cm). alpha- and beta-adrenergic and catecholamine synthesis inhibition and intraprocedural anesthesia monitoring were used. Safety was assessed by recording ablation-related complications. Complete ablation was defined as a lack of enhancement within the ablation zone on follow-up computed tomography. No serious adverse sequelae were observed. Complete ablation was achieved in six of seven metastases (mean follow-up, 12.3 months; range, 2.5-28 months). In conclusion, RF ablation may be safely performed for metastatic pheochromocytoma given careful attention to peri-procedural management.

Ex vivo rapamycin generates apoptosis-resistant donor Th2 cells that persist in vivo and prevent hemopoietic stem cell graft rejection

Because ex vivo rapamycin generates murine Th2 cells that prevent Graft-versus-host disease more potently than control Th2 cells, we hypothesized that rapamycin would generate Th2/Tc2 cells (Th2/Tc2.R cells) that abrogate fully MHC-disparate hemopoietic stem cell rejection more effectively than control Th2/Tc2 cells. In a B6-into-BALB/c graft rejection model, donor Th2/Tc2.R cells were indeed enriched in their capacity to prevent rejection; importantly, highly purified CD4+ Th2.R cells were also highly efficacious for preventing rejection. Rapamycin-generated Th2/Tc2 cells were less likely to die after adoptive transfer, accumulated in vivo at advanced proliferative cycles, and were present in 10-fold higher numbers than control Th2/Tc2 cells. Th2.R cells had a multifaceted, apoptosis-resistant phenotype, including: 1) reduced apoptosis after staurosporine addition, serum starvation, or CD3/CD28 costimulation; 2) reduced activation of caspases 3 and 9; and 3) increased anti-apoptotic Bcl-xL expression and reduced proapoptotic Bim and Bid expression. Using host-versus-graft reactivity as an immune correlate of graft rejection, we found that the in vivo efficacy of Th2/Tc2.R cells 1) did not require Th2/Tc2.R cell expression of IL-4, IL-10, perforin, or Fas ligand; 2) could not be reversed by IL-2, IL-7, or IL-15 posttransplant therapy; and 3) was intact after therapy with Th2.R cells relatively devoid of Foxp3 expression. We conclude that ex vivo rapamycin generates Th2 cells that are resistant to apoptosis, persist in vivo, and effectively prevent rejection by a mechanism that may be distinct from previously described graft-facilitating T cells.