Ethnic diversity in treatment response for colorectal cancer: proof of concept for radiomics-driven enrichment trials

BACKGROUND

Several barriers hamper recruitment of diverse patient populations in multicenter clinical trials which determine efficacy of new systemic cancer therapies.

PURPOSE

We assessed if quantitative analysis of computed tomography (CT) scans of metastatic colorectal cancer (mCRC) patients using imaging features that predict overall survival (OS) can unravel the association between ethnicity and efficacy.

METHODS

We retrospectively analyzed CT images from 1584 mCRC patients in two phase III trials evaluating FOLFOX ± panitumumab (n = 331, 350) and FOLFIRI ± aflibercept (n = 437, 466) collected from August 2006 to March 2013. Primary and secondary endpoints compared RECIST1.1 response at month-2 and delta tumor volume at month-2, respectively. An ancillary study compared imaging phenotype using a peer-reviewed radiomics-signature combining 3 imaging features to predict OS landmarked from month-2. Analysis was stratified by ethnicity.

RESULTS

In total, 1584 patients were included (mean age, 60.25 ± 10.57 years; 969 men). Ethnicity was as follows: African (n = 50, 3.2%), Asian (n = 66, 4.2%), Caucasian (n = 1413, 89.2%), Latino (n = 27, 1.7%), Other (n = 28, 1.8%). Overall baseline tumor volume demonstrated Africans and Caucasians had more advanced disease (p < 0.001). Ethnicity was associated with treatment response. Response per RECIST1.1 at month-2 was distinct between ethnicities (p = 0.048) with higher response rate (55.6%) in Latinos. Overall delta tumor volume at month-2 demonstrated that Latino patients more likely experienced response to treatment (p = 0.021). Radiomics phenotype was also distinct in terms of tumor radiomics heterogeneity (p = 0.023).

CONCLUSION

This study highlights how clinical trials that inadequately represent minority groups may impact associated translational work. In appropriately powered studies, radiomics features may allow us to unravel associations between ethnicity and treatment efficacy, better elucidate mechanisms of resistance, and promote diversity in trials through predictive enrichment.

CLINICAL RELEVANCE STATEMENT

Radiomics could promote clinical trial diversity through predictive enrichment, hence benefit to historically underrepresented racial/ethnic groups that may respond variably to treatment due to socioeconomic factors and built environment, collectively referred to as social determinants of health.

KEY POINTS

•Findings indicate ethnicity was associated with treatment response across all 3 endpoints. First, response per RECIST1.1 at month-2 was distinct between ethnicities (p = 0.048) with higher response rate (55.6%) in Latinos. •Second, the overall delta tumor volume at month-2 demonstrated that Latino patients were more likely to experience response to treatment (p = 0.021). Radiomics phenotype was also distinct in terms of tumor radiomics heterogeneity (p = 0.023).

Model-based approach to identify predictors of paclitaxel-induced myelosuppression in "real-world" administration

Taxanes are currently the most frequently used chemotherapeutic agents in cancer care, where real-world use has focused on minimizing adverse events and standardizing the delivery. Myelosuppression is a well-characterized, adverse pharmacodynamic effect of taxanes. Electronic health records (EHRs) comprise data collected during routine clinical care that include patients with heterogeneous demographic, clinical, and treatment characteristics. Application of pharmacokinetic/pharmacodynamic (PK/PD) modeling to EHR data promises new insights on the real-world use of taxanes and strategies to improve therapeutic outcomes especially for populations who are typically excluded from clinical trials, including the elderly. This investigation: (i) leveraged previously published PK/PD models developed with clinical trial data and addressed challenges to fit EHR data, and (ii) evaluated predictors of paclitaxel-induced myelosuppression. Relevant EHR data were collected from patients treated with paclitaxel-containing chemotherapy at Inova Schar Cancer Institute between 2015 and 2019 (n = 405). Published PK models were used to simulate mean individual exposures of paclitaxel and carboplatin, which were linearly linked to absolute neutrophil count (ANC) using a published semiphysiologic myelosuppression model. Elderly patients (≥70 years) constituted 21.2% of the dataset and 2274 ANC measurements were included in the analysis. The PD parameters were estimated and matched previously reported values. The baseline ANC and chemotherapy regimen were significant predictors of paclitaxel-induced myelosuppression. The nadir ANC and use of supportive treatments, such as growth factors and antimicrobials, were consistent across age quantiles suggesting age had no effect on paclitaxel-induced myelosuppression. In conclusion, EHR data could complement clinical trial data in answering key therapeutic questions.

Early Readout on Overall Survival of Patients With Melanoma Treated With Immunotherapy Using a Novel Imaging Analysis

IMPORTANCE

Existing criteria to estimate the benefit of a therapy in patients with cancer rely almost exclusively on tumor size, an approach that was not designed to estimate survival benefit and is challenged by the unique properties of immunotherapy. More accurate prediction of survival by treatment could enhance treatment decisions.

OBJECTIVE

To validate, using radiomics and machine learning, the performance of a signature of quantitative computed tomography (CT) imaging features for estimating overall survival (OS) in patients with advanced melanoma treated with immunotherapy.

DESIGN, SETTING, AND PARTICIPANTS

This prognostic study used radiomics and machine learning to retrospectively analyze CT images obtained at baseline and first follow-up and their associated clinical metadata. Data were prospectively collected in the KEYNOTE-002 (Study of Pembrolizumab [MK-3475] Versus Chemotherapy in Participants With Advanced Melanoma; 2017 analysis) and KEYNOTE-006 (Study to Evaluate the Safety and Efficacy of Two Different Dosing Schedules of Pembrolizumab [MK-3475] Compared to Ipilimumab in Participants With Advanced Melanoma; 2016 analysis) multicenter clinical trials. Participants included 575 patients with a diagnosis of advanced melanoma who were randomly assigned to training and validation sets. Data for the present study were collected from November 20, 2012, to June 3, 2019, and analyzed from July 1, 2019, to September 15, 2021.

INTERVENTIONS

KEYNOTE-002 featured trial groups testing intravenous pembrolizumab, 2 mg/kg or 10 mg/kg every 2 or every 3 weeks based on randomization, or investigator-choice chemotherapy; KEYNOTE-006 featured trial groups testing intravenous ipilimumab, 3 mg/kg every 3 weeks and intravenous pembrolizumab, 10 mg/kg every 2 or 3 weeks based on randomization.

MAIN OUTCOMES AND MEASURES

The performance of the signature CT imaging features for estimating OS at the month 6 posttreatment landmark in patients who received pembrolizumab was measured using an area under the time-dependent receiver operating characteristics curve (AUC).

RESULTS

A random forest model combined 25 imaging features extracted from tumors segmented on CT images to identify the combination (signature) that best estimated OS with pembrolizumab in 575 patients. The signature combined 4 imaging features, 2 related to tumor size and 2 reflecting changes in tumor imaging phenotype. In the validation set (287 patients treated with pembrolizumab), the signature reached an AUC for estimation of OS status of 0.92 (95% CI, 0.89-0.95). The standard method, Response Evaluation Criteria in Solid Tumors 1.1, achieved an AUC of 0.80 (95% CI, 0.75-0.84) and classified tumor outcomes as partial or complete response (93 of 287 [32.4%]), stable disease (90 of 287 [31.3%]), or progressive disease (104 of 287 [36.2%]).

CONCLUSIONS AND RELEVANCE

The findings of this prognostic study suggest that the radiomic signature discerned from conventional CT images at baseline and on first follow-up may be used in clinical settings to provide an accurate early readout of future OS probability in patients with melanoma treated with single-agent programmed cell death 1 blockade.

An imaging signature to predict outcome in metastatic colorectal cancer using routine computed tomography scans

BACKGROUND & AIMS

Quantitative analysis of computed tomography (CT) scans of patients with metastatic colorectal cancer (mCRC) can identify imaging signatures that predict overall survival (OS).

METHODS

We retrospectively analysed CT images from 1584 mCRC patients on two phase III trials evaluating FOLFOX ± panitumumab (n = 331, 350) and FOLFIRI ± aflibercept (n = 437, 466). In the training set (n = 720), an algorithm was trained to predict OS landmarked from month 2; the output was a signature value on a scale from 0 to 1 (most to least favourable predicted OS). In the validation set (n = 864), hazard ratios (HRs) evaluated the association of the signature with OS using RECIST1.1 as a benchmark of comparison.

RESULTS

In the training set, the selected signature combined three features - change in tumour volume, change in tumour spatial heterogeneity, and tumour volume - to predict OS. In the validation set, RECIST1.1 classified patients in three categories: response (n = 166, 19.2%), stable disease (n = 636, 73.6%), and progression (n = 62, 7.2%). The HR was 3.93 (2.79-5.54). Using the same distribution for the signature, the HR was 21.04 (14.88-30.58), showing an incremental prognostic separation. Stable disease by RECIST1.1 was reclassified by the signature along a continuum where patients belonging to the most and least favourable signature quartiles had a median OS of 40.73 (28.49 to NA) months (n = 94) and 7.03 (5.66-7.89) months (n = 166), respectively.

CONCLUSIONS

A signature combining three imaging features provides early prognostic information that can improve treatment decisions for individual patients and clinical trial analyses.

Abstract PO022: Multidimensional longitudinal assessment of patients under treatment for advanced endometrial cancer: a new tool to advance research on human disease

Evolutionary biology-based methods to characterize human cancer increasingly inform screening, surveillance, and early stage disease treatment strategies. Advanced metastatic disease presents distinct challenges in research and effective treatment. We have established the Advanced Solid Tumor Registry at the Inova Schar Cancer Institute to systematically track quantitative behavior of advanced solid tumors in a “real world” treatment setting. The study supports collection of serial: plasma samples for ctDNA analysis, computed tomography digital images and semi-automated segmentation of lesions for tumor burden volume measurement, and collection of tumor marker measures among patients receiving routine, longitudinal treatment in a community oncology practice. At submission, the study has enrolled 53 patients, 6 with recurrent metastatic endometrial cancer. Study operations have been enhanced by development of R code and workflow to enable graphical display for individual patients in clinically relevant time. In addition to enhancing clinical decision-making for the individual patients, the collective endometrial cancer patient data currently cover 207 patient-months of observation, 119 circulating marker time-points, 73 CT scans, 27 individual lesions, and 20 different courses of treatment. Treatments included palliative radiation, and: cytotoxic, hormonal, immune-, and targeted therapeutics. We propose this registry represents a new tool to support application of evolutionary science-based methods to clinical care and reciprocally to collect “real world” data with sufficient detail to inform computational science assumptions and inferences in multi-scale modeling projects. In this pilot study, individual cases effectively display multiple observations relevant to understanding treatment response in advanced metastatic disease in the clinical care environment. This project was supported, in part, by R01-CA194783.

Citation Format: Erik Dvergsten, Sanja Karovic, Vasiliki Thomeas-McEwing, Danielle Kimble, Pingzhen Guo, Hao Yang, Binsheng Zhao, Lawrence H. Schwartz, Michael L. Maitland. Multidimensional longitudinal assessment of patients under treatment for advanced endometrial cancer: a new tool to advance research on human disease [abstract]. In: Proceedings of the AACR Virtual Special Conference: Endometrial Cancer: New Biology Driving Research and Treatment; 2020 Nov 9-10. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(3_Suppl):Abstract nr PO022.

Discordance between central versus local response assessments in neuroendocrine tumor (NET) patients (pts) enrolled in A021202

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Background: Assessment of tumor response in extrapancreatic NETs with metastases can be very challenging. Previous studies suggest a high degree of discordance between local and central imaging reviews, which has implications for clinical practice and trial design. Methods: Serial images archived from a randomized phase II trial (A021202) of pazopanib vs placebo in progressive non-pancreatic NETs were evaluated by central review, with real-time review conducted at the time of locally interpreted progressive disease (PD). The primary endpoint of the trial was progression-free survival (PFS) by central review. Discordances between central (Alliance Imaging Core Laboratory) and local (investigator-reported) reviews were assessed. Scan-level and pt-level results across both treatment arms were evaluated. Kappa tests were used to test concordance based on source of review. Results: 151 pts had a total of 724 scans with response adjudication by both local and central RECIST review. Discordance was observed in both directions. Overall, 20% of scans (143/724) had discordant classifications. The most common discordances were: stable disease (SD) on local vs. PD on central review (82/143=57%), and PD on local vs. SD on central review (32/143=22%). On a pt level, 78 of 151 pts (52%) had discordant reviews; 8 had >1 type of discordance. Overall, 30% of pts (N=45) had a determination of PD on central review, but SD or better on local review, potentially resulting in excessive exposure to therapy. In contrast, 20% (N=30) were classified as PD on local read but SD or better on real-time central review (which did not necessarily translate into an abbreviated course of treatment). Cohen’s kappa statistics revealed only moderate concordance between local and central reviewers both at the scan (K=0.48, 95% CI: 0.42 – 0.55) and pt (K=0.41, 95% CI: 0.32 – 0.5) levels, with no significant influence by treatment arm, primary tumor site, tumor functionality, histology, differentiation or primary disease spread. Conclusions: Discordance was observed in both directions, where 30% of pts were potentially kept on study drug too long (based on central read), and 20% would have been taken off study treatment early for local PD were it not for real-time central review. Although this bidirectional discordance did not affect the overall findings of the PFS outcome between arms in the trial, these analyses highlight the high prevalence of discordance, the potential to negatively influence treatment duration in both directions, and the need for more straightforward methods of assessing treatment response in carcinoid. Support: U10CA180821, U10CA180882, U24CA196171; NETRF Investigator Award; https://acknowledgments.alliancefound.org Clinical trial information: NCT01841736.

Evaluation of publicly available in vitro drug sensitivity models for ovarian and uterine cancer

OBJECTIVE

Publicly available data on drug sensitivity for cancer cell lines have been curated into a single, integrated database, PharmacoDB. The contributing datasets report modeled estimates of drug effect from high throughput assays. These databases have been informative for developing new broad insights, but the reliability of these data specifically for drugs used to treat ovarian and uterine cancers in related cell lines has not been reported.

METHODS

In vitro viability assays were performed on A2780, OVCAR-3, TOV-21G, and RL95-2 cells with nine drugs to produce high resolution exposure-response curves. Lab generated data were compared to publicly available datasets by IC₂₀, IC₅₀, and IC₈₀ values, and the area between the logarithmic logistic regression curves.

RESULTS

For exposure-response curve comparisons with clinically indicated drugs between lab generated and publicly available data, the majority had area-between-curves less than 20%, indicating similarity. However, 15 out of 40 of these dataset curves were incomplete as indicated by the lack of, or extrapolated, IC₅₀ value. The common ovarian and uterine cancer drug, carboplatin, exemplified this incomplete status as all of the available dataset curves were incomplete and therefore non-informative.

CONCLUSIONS

For gynecologic malignancy cell line models, experimental drug sensitivity data is comparable to the available data in PharmacoDB when exposure-response curves are complete. Incomplete exposure-response curves due to incomplete concentration ranges tested and related extrapolation of IC values can mislead individual drug/cell line pair data for downstream applications.

Comparing RECIST 1.1 and iRECIST in advanced melanoma patients treated with pembrolizumab in a phase II clinical trial

OBJECTIVES

To compare tumor best overall response (BOR) by RECIST 1.1 and iRECIST, to explore the incidence of pseudoprogression in melanoma treated with pembrolizumab, and to assess the impact of pseudoprogression on overall survival (OS).

METHODS

A total of 221 patients with locally advanced/unresectable melanoma who received pembrolizumab as part of KEYNOTE-002 trial were included in this study. Radiological assessment of imaging was centrally reviewed to assess tumor response. Incidence of discordance in BOR between RECIST 1.1 and iRECIST as well as rate of pseudoprogression were measured. OS of patients with pseudoprogression was compared with that of those with uncontrolled disease.

RESULTS

Of the 221 patients in this cohort, 136 patients developed PD as per RECIST v1.1 and 78 patients with PD continued treatment and imaging beyond initial RECIST 1.1-defined PD. Among the 78 patients who continued therapy and imaging post-progression, RECIST 1.1 and iRECIST were discordant in 10 patients (12.8%) and pseudoprogression was encountered in 14 patients (17.9%). OS of patients with pseudoprogression was longer than that of patients with uncontrolled disease/true progression (29.9 months versus 8.0 months, p value < 0.001).

CONCLUSIONS

Effectiveness of immunotherapy in clinical trials depends on the criterion used to assess tumor response (RECIST 1.1 vs iRECIST) with iRECIST being more appropriate to detect pseudoprogression and potentially prevent premature termination of effective therapy. Pseudoprogression was associated with improved OS in comparison with that of patients with uncontrolled disease.

KEY POINTS

• Discordance between iRECIST and RECIST 1.1 was found in 12.8% of unresectable melanoma patients on pembrolizumab who continued therapy beyond initial RECIST 1.1-defined progression. • Pseudoprogression, captured with iRECIST, occurred in 17.9% and was significantly associated with improved overall survival in comparison with uncontrolled disease.

Enhanced Detection of Treatment Effects on Metastatic Colorectal Cancer with Volumetric CT Measurements for Tumor Burden Growth Rate Evaluation

PURPOSE

Mathematical models combined with new imaging technologies could improve clinical oncology studies. To improve detection of therapeutic effect in patients with cancer, we assessed volumetric measurement of target lesions to estimate the rates of exponential tumor growth and regression as treatment is administered.

EXPERIMENTAL DESIGN

Two completed phase III trials were studied (988 patients) of aflibercept or panitumumab added to standard chemotherapy for advanced colorectal cancer. Retrospectively, radiologists performed semiautomated measurements of all metastatic lesions on CT images. Using exponential growth modeling, tumor regression (d) and growth (g) rates were estimated for each patient's unidimensional and volumetric measurements.

RESULTS

Exponential growth modeling of volumetric measurements detected different empiric mechanisms of effect for each drug: panitumumab marginally augmented the decay rate [tumor half-life; d [IQR]: 36.5 days (56.3, 29.0)] of chemotherapy [d: 44.5 days (67.2, 32.1), two-sided Wilcoxon P = 0.016], whereas aflibercept more significantly slowed the growth rate [doubling time; g = 300.8 days (154.0, 572.3)] compared with chemotherapy alone [g = 155.9 days (82.2, 347.0), P ≤ 0.0001]. An association of g with overall survival (OS) was observed. Simulating clinical trials using volumetric or unidimensional tumor measurements, fewer patients were required to detect a treatment effect using a volumetric measurement-based strategy (32-60 patients) than for unidimensional measurement-based strategies (124-184 patients).

CONCLUSIONS

Combined tumor volume measurement and estimation of tumor regression and growth rate has potential to enhance assessment of treatment effects in clinical studies of colorectal cancer that would not be achieved with conventional, RECIST-based unidimensional measurements.

Abstract 5451: Longitudinal proteomic assessment of patient with metastatic apocrine adenocarcinoma reveals evolutionary selection for androgen-receptor-dependence and therapeutic response

Combined use of new molecular diagnostic and imaging methods could improve care of individual patients with rare cancers.

A 57-year-old developed apocrine adenocarcinoma of the left axilla with regional lymph node metastasis detected at initial surgery. After adjuvant regional radiotherapy, metastases developed and over the subsequent 7 years he received serial systemic therapy with 11 different regimens. Expression of 128 proteins/phosphoproteins was evaluated in 8 tissue samples from diagnosis, progressive adenopathy at 45 months, brain metastases at 60 months, and abdominal metastases at 63 months by CLIA-standardized reverse phase phosphoprotein arrays (RPPA). Tumor burden was estimated by quantifying the volume of individual lesions with semi-automated segmentation algorithms on serially collected CT images.

Next-generation sequencing (NGS) revealed a PIK3CA K111T mutation, prompting treatment with sirolimus 28 months after diagnosis. Seventeen months later, new neoplastic adenopathy emerged. NGS revealed a new PIK3CA M610V mutation. Semiquantitative scoring of RPPA demonstrated relative increase in AKT (from 0.72 to 0.9) and mTOR (from 0.55 to 0.8) pathway activation. The relative estimated tumor burden (RETB) was 21,145 mm3. Over 6 months of docetaxel therapy the RETB decreased to 12,077 mm3. The patient subsequently received pembrolizumab with increased RETB (71,308 mm3). Gemcitabine appeared to stabilize the RETB (73,168 mm3), but brain metastases emerged. The patient underwent craniotomy, began paclitaxel therapy, and then RETB declined to 35,623 mm3. But new symptomatic abdominal metastases prompted surgical resection. The patient then received the PI3K inhibitor taselisib; however, after an initial decrease, RETB rose to 31,208 mm3.

At this point, the patient began bicalutamide therapy. NGS of the primary mass and the initial metastatic adenopathy revealed no amplification of the androgen receptor (AR). But RPPA demonstrated inversion of the ratio of measured phosphorylated AR S81 to AR S650, suggesting primarily cytoplasmic AR in tumor through 45 months but nuclear AR in samples resected at 60 and 63 months. Immunohistochemistry revealed 3+ nuclear AR expression in the latter metastatic tissue. After 9 months of bicalutamide, enzalutamide and leuprolide were administered for 7 months (final RETB = 1,555 mm3). Treatment continued beyond the study period.

Tumor burden assessment by new CT imaging measurement methods, combined with RPPA could improve adaptive, responsive, therapy for patients with rare tumors. We identified the phenotypic evolution of androgen-driven growth of apocrine adenocarcinoma after cytotoxic and PI3K-mTOR inhibitor therapy. Protein-based diagnostics revealed an effective treatment strategy in late metastatic disease that was not indicated by NGS testing.

Citation Format: Erik Dvergsten, Anthony Serritella, Danielle Kimble, Malcom McIver, Sanja Karovic, Vasiliki Thomeas-McEwing, Hao Yang, Manish R. Sharma, Thomas P. Conrads, Mariaelena Pierobon, Peter Pytel, Binsheng Zhao, Lawrence H. Schwartz, Emanuel F. Petricoin, Russell Szmulewitz, Michael L. Maitland. Longitudinal proteomic assessment of patient with metastatic apocrine adenocarcinoma reveals evolutionary selection for androgen-receptor-dependence and therapeutic response [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5451.

Vol-PACT: A Foundation for the NIH Public-Private Partnership That Supports Sharing of Clinical Trial Data for the Development of Improved Imaging Biomarkers in Oncology

PURPOSE

To develop a public-private partnership to study the feasibility of a new approach in collecting and analyzing clinically annotated imaging data from landmark phase III trials in advanced solid tumors.

PATIENTS AND METHODS

The collection of clinical trials fulfilled the following inclusion criteria: completed randomized trials of > 300 patients, highly measurable solid tumors (non-small-cell lung cancer, colorectal cancer, renal cell cancer, and melanoma), and required sponsor and institutional review board sign-offs. The new approach in analyzing computed tomography scans was to transfer to an academic image analysis laboratory, draw contours semi-automatically by using in-house-developed algorithms integrated into the open source imaging platform Weasis, and perform serial volumetric measurement.

RESULTS

The median duration of contracting with five sponsors was 12 months. Ten trials in 7,085 patients that covered 12 treatment regimens across 20 trial arms were collected. To date, four trials in 3,954 patients were analyzed. Source imaging data were transferred to the academic core from 97% of trial patients (n = 3,837). Tumor imaging measurements were extracted from 82% of transferred computed tomography scans (n = 3,162). Causes of extraction failure were nonmeasurable disease (n = 392), single imaging time point (n = 224), and secondary captured images (n = 59). Overall, clinically annotated imaging data were extracted in 79% of patients (n = 3,055), and the primary trial end point analysis in each trial remained representative of each original trial end point.

CONCLUSION

The sharing and analysis of source imaging data from large randomized trials is feasible and offer a rich and reusable, but largely untapped, resource for future research on novel trial-level response and progression imaging metrics.

Clinical pharmacodynamic/exposure characterisation of the multikinase inhibitor ilorasertib (ABT-348) in a phase 1 dose-escalation trial

Background

Ilorasertib (ABT-348) inhibits Aurora and VEGF receptor (VEGFR) kinases. Patients with advanced solid tumours participated in a phase 1 dose-escalation trial to profile the safety, tolerability, and pharmacokinetics of ilorasertib.

Methods

Ilorasertib monotherapy was administered at 10–180 mg orally once daily (Arm I, n = 23), 40–340 mg orally twice daily (Arm II, n = 28), or 8–32 mg intravenously once daily (Arm III, n = 7), on days 1, 8, and 15 of each 28-day cycle.

Results

Dose-limiting toxicities were predominantly related to VEGFR inhibition. The most frequent treatment-emergent adverse events ( > 30%) were: fatigue (48%), anorexia (34%), and hypertension (34%). Pharmacodynamic markers suggested that ilorasertib engaged VEGFR2 and Aurora B kinase, with the VEGFR2 effects reached at lower doses and exposures than Aurora inhibition effects. In Arm II, one basal cell carcinoma patient (40 mg twice daily (BID)) and one patient with adenocarcinoma of unknown primary site (230 mg BID) had partial responses.

Conclusions

In patients with advanced solid tumours, ilorasertib treatment resulted in evidence of engagement of the intended targets and antitumour activity, but with maximum inhibition of VEGFR family kinases occurring at lower exposures than typically required for inhibition of Aurora B in tissue.

Clinical Trial Registration: NCT01110486

Pharmaco-kinetics/dynamics (PK/PD) evaluation and individual patient cross-over studies with growth trajectory assessment to adaptively develop ilorasertib

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Background: We evaluated PK/PD of the AURK B/VEGFR2 inhibitor ilorasertib. To detect activity in CDKN2A-deficient tumors, we measured changes-in-tumor-burden by CT-volume before, during, and after discontinuation of therapy. Methods: Study 1: open-label, dose-escalation, phase 1 in 58 patients (pts) with advanced solid tumors. Arms I, II, and III assigned: 23 pts (10–180 mg oral QD), 28 pts (40–340 mg oral BID), and 7 pts (8–32 mg i.v. QD), to ilorasertib monotherapy Days 1, 8, and 15 every 28 days. We evaluated PK/PD for validated biomarkers: change-in-diastolic blood pressure (ΔDBP), change-in-plasma [PlGF] (ΔPlGF), and change-in phosphorylated histone H3 (Δ%pHH3) in skin biopsies. Study 2: open-label trial, of 10 solid tumor pts with CLIA-lab-detected CDKN2A disruption. Pts received ilorasertib 250 mg oral BID on same schedule. On CT images collected prior to screening, and ~ study days -7, 49, and 98 individual lesion volumes were determined by central lab semi-automated segmentation algorithms on DICOM files. Pts who tolerated ilorasertib with RECIST-stable disease at day 98 discontinued ilorasertib for 42 days and underwent re-imaging before restarting ilorasertib. Results: Study 1: the DLTs and frequent adverse events reflected VEGFR2 inhibition. PK/PD analysis showed peak VEGFR2 inhibition on ΔDBP and ΔPlGF at lower systemic concentrations than for peak AURKB-inhibition detected with Δ%pHH3. Two pts in Arm II had partial response; one had homozygous deletion of CDKN2Aby FISH. Pre-clinically the CDKN2A-deficient cell lines (OVCAR5, MDA MB 231, A549) were among the most ilorasertib-sensitive. At time of submission, Study II enrolled 10 pts, with 5 evaluable for longitudinal tumor burden assessments. Three pts had sustained negative growth trajectories after ilorasertib therapy; one of these had positive growth after cessation of treatment but restabilization of disease after restarting ilorasertib. Conclusions: The development plan adapted to the in-human PK/PD assessment. We prospectively conducted individual change-in-tumor burden cross-over studies to assess clinically the sensitivity of CDKN2A-deficient tumors. Clinical trial information: NCT02540876 and NCT01110486.

Patient-Level Adverse Event Patterns in a Single-Institution Study of the Multi-Kinase Inhibitor Sorafenib

Novel characterization of patterns of adverse events (AEs) of kinase inhibitors (KIs) could reveal new insights on human molecular physiology and methods to improve the therapeutic index of KIs. Incidence and severity of AEs for each of 157 patients enrolled in sorafenib clinical trials were determined for three clinically relevant treatment intervals: weeks 0–3, weeks 3–7, and after 7 weeks. The most common within patient co‐occurrences were mucositis with dermatologic events: hand‐foot syndrome (HFS; odds ratio [OR] = 4.36; p = 0.0017) and rash (OR = 5.32; p < 0.001). Prevalence of severe: alopecia (p = 0.02), diarrhea (p < 0.001), and fatigue (p = 0.005) increased over the course of therapy. Incidence of HFS (60%) and diarrhea (25%) increased up to a minimum steady‐state concentration (approximately 5 mcg mL^‐1) and plateaued thereafter. Common AEs of sorafenib occur in distinct temporal and tissue distribution patterns and this analysis identified unrecognized relationships among mechanism‐dependent and independent effects of a KI.

Comparative Effects of CT Imaging Measurement on RECIST End Points and Tumor Growth Kinetics Modeling

Quantitative assessments of tumor burden and modeling of longitudinal growth could improve phase II oncology trials. To identify obstacles to wider use of quantitative measures we obtained recorded linear tumor measurements from three published lung cancer trials. Model-based parameters of tumor burden change were estimated and compared with similarly sized samples from separate trials. Time-to-tumor growth (TTG) was computed from measurements recorded on case report forms and a second radiologist blinded to the form data. Response Evaluation Criteria in Solid Tumors (RECIST)-based progression-free survival (PFS) measures were perfectly concordant between the original forms data and the blinded radiologist re-evaluation (intraclass correlation coefficient = 1), but these routine interrater differences in the identification and measurement of target lesions were associated with an average 18-week delay (range, -20 to 55 weeks) in TTG (intraclass correlation coefficient = 0.32). To exploit computational metrics for improving statistical power in small clinical trials will require increased precision of tumor burden assessments.

Serum C-Telopeptide Collagen Crosslinks and Plasma Soluble VEGFR2 as Pharmacodynamic Biomarkers in a Trial of Sequentially Administered Sunitinib and Cilengitide

PURPOSE

Fit-for-purpose pharmacodynamic biomarkers could expedite development of combination antiangiogenic regimens. Plasma sVEGFR2 concentrations ([sVEGFR2]) mark sunitinib effects on the systemic vasculature. We hypothesized that cilengitide would impair microvasculature recovery during sunitinib withdrawal and could be detected through changes in [sVEGFR2].

EXPERIMENTAL DESIGN

Advanced solid tumor patients received 50 mg sunitinib daily for 14 days. For the next 14 days, patients were randomized to arm A (cilengitide 2,000 mg administered intravenously twice weekly) or arm B (no treatment). The primary endpoint was change in [sVEGFR2] between days 14 and 28. A candidate pharmacodynamic biomarker of cilengitide inhibition of integrin αvβ3, serum c-telopeptide collagen crosslinks (CTx), was also measured.

RESULTS

Of 21 patients, 14 (7 per arm) received all treatments without interruption and had all blood samples available for analysis. The mean change and SD of [sVEGFR2] for all sunitinib-treated patients was consistent with previous data. There was no significant difference in the mean change in [sVEGFR2] from days 14 to 28 between the arms [arm A: 2.8 ng/mL; 95% confidence interval (CI), 2.1-3.6 vs. arm B: 2.0 ng/mL; 95% CI, 0.72-3.4; P = 0.22, 2-sample t test]. Additional analyses suggested (i) prior bevacizumab therapy to be associated with unusually low baseline [sVEGFR2] and (ii) sunitinib causes measurable changes in CTx.

CONCLUSIONS

Cilengitide had no measurable effects on any circulating biomarkers. Sunitinib caused measurable declines in serum CTx. The properties of [sVEGFR2] and CTx observed in this study inform the design of future combination antiangiogenic therapy trials.

Predicting Response to Histone Deacetylase Inhibitors Using High-Throughput Genomics

BACKGROUND

Many disparate biomarkers have been proposed as predictors of response to histone deacetylase inhibitors (HDI); however, all have failed when applied clinically. Rather than this being entirely an issue of reproducibility, response to the HDI vorinostat may be determined by the additive effect of multiple molecular factors, many of which have previously been demonstrated.

METHODS

We conducted a large-scale gene expression analysis using the Cancer Genome Project for discovery and generated another large independent cancer cell line dataset across different cancers for validation. We compared different approaches in terms of how accurately vorinostat response can be predicted on an independent out-of-batch set of samples and applied the polygenic marker prediction principles in a clinical trial.

RESULTS

Using machine learning, the small effects that aggregate, resulting in sensitivity or resistance, can be recovered from gene expression data in a large panel of cancer cell lines.This approach can predict vorinostat response accurately, whereas single gene or pathway markers cannot. Our analyses recapitulated and contextualized many previous findings and suggest an important role for processes such as chromatin remodeling, autophagy, and apoptosis. As a proof of concept, we also discovered a novel causative role for CHD4, a helicase involved in the histone deacetylase complex that is associated with poor clinical outcome. As a clinical validation, we demonstrated that a common dose-limiting toxicity of vorinostat, thrombocytopenia, can be predicted (r = 0.55, P = .004) several days before it is detected clinically.

CONCLUSION

Our work suggests a paradigm shift from single-gene/pathway evaluation to simultaneously evaluating multiple independent high-throughput gene expression datasets, which can be easily extended to other investigational compounds where similar issues are hampering clinical adoption.

Sorafenib dose escalation is not uniformly associated with blood pressure elevations in normotensive patients with advanced malignancies

Hypertension with vascular endothelial growth factor (VEGF) receptor inhibitors is associated with superior treatment outcomes for advanced cancer patients. To determine whether increased doses of sorafenib cause incremental increases in blood pressure (BP) we measured 12-hour ambulatory BP in 41 normotensive advanced solid tumor patients in a randomized dose escalation study. After 7 days’ sorafenib (400mg BID) mean diastolic BP (DBP) increased in both study groups. After dose escalation, group A (400mg TID) had marginally significant further increase in 12-hour mean DBP (p=0.053) but group B (600mg BID) did not achieve statistically significant increases (p=0.25). Within groups, individuals varied in BP response to sorafenib dose escalation, but these differences did not correlate with changes in steady state plasma sorafenib concentrations. These findings in normotensive patients suggest BP is a complex pharmacodynamic biomarker of VEGF inhibition. Patients have intrinsic differences in sensitivity to the BP elevating effects of sorafenib.

Technical considerations in the development of circulating peptides as pharmacodynamic biomarkers for angiogenesis inhibitors

To determine the biological reproducibility and estimate relevant covariates for candidate circulating biomarkers of angiogenesis, we conducted 3 sub-studies with ≤15 subjects each. In study 1, 6 healthy subjects provided 13 blood samples across 14-24 days. In study 2, 15 advanced solid tumor patients provided single blood samples before, and approximately 8 and 40 days after sorafenib treatment. In study 3, 4 healthy subjects provided blood samples on 3 occasions over 14 days, processed simultaneously in 2 different laboratories at a single institution. Vascular endothelial growth factor (VEGFA), soluble VEGF receptor-2 (sVEGFR2), and angiopoietin-2 (Ang2) concentrations in plasma and serum were determined by standard immunoassays. Ang2 and sVEGFR2 demonstrated low variance within and high variance across individuals reflected by the high intraclass correlation coefficient (for Ang2: 0.86 for plasma, 0.89 for serum; for sVEGFR2: 0.91 for plasma, 0.87 for serum). Repeated measures linear modeling from 15 patients demonstrated increased Ang2 (P ≤ 0.05) and decreased sVEGFR2 (P ≤ 0.05) after exposure to sorafenib. VEGFA had high intraindividual variance, and study 3 demonstrated the laboratory to have significant effects on plasma measurements (P ≤ 0.05). The biological reproducibility of sVEGFR2 and Ang2 support further use of these markers in studies of vasculature-targeted therapeutics.

Dose-ranging randomized pharmacokinetic (PK) and pharmacodynamic (PD) study of vorinostat in patients with advanced solid tumors

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Background: Continuous 400 mg daily vorinostat (V) is effective treatment for cutaneous T-cell lymphoma, but has displayed erratic activity in combination therapy for solid tumors. Short-course high-dose vorinostat may have a better therapeutic index for solid tumors, but dose/exposure/PD relationships have not been tested in sufficiently powered studies. Methods: Patients (pts) were randomized to either V 1600 mg daily, days (d) 1-3 then 400 mg d8-10 or 400 mg d1-3 then 1600 mg d8-10 with complete PK sampling on d3 and d10 to determine the increase in Cmax upon increasing V from 400 to1600 mg. To assess safety and tolerability of high dose V added to carboplatin, pts then received high dose V d15-17 with carboplatin AUC 5 on d17; this combination was repeated every 21d thereafter. Platelet counts were determined weekly. To detect with 80% power a difference in vorinostat Cmax between 400 and 1600 mg required at least 10 pts in each sequence. In vitro studies of gene expression in solid tumors suggested as a secondary endpoint the frequency of pts achieving Cmax > 1000 ng/mL. Results: 24 pts (11 men/13 women) enrolled between April 2011 and March 2012 and were evaluable for study endpoints. No sequence dependence of change in Cmax was detected. Cmax for V 1600 mg was nearly double that for 400 mg (1184+/-631 vs. 616+/-442 ng/mL, p < 0.001). The PD effect on platelets (d10) was greater for the higher dose (median -76 vs. -14 K/µL, p= 0.02). There were no dose limiting toxicities. Of 24 pts, 11 achieved Cmax > 1000 ng/mL. Conclusions: The 1600 mg dose of vorinostat results in a higher Cmax than 400 mg and greater PD effect than 400 mg and is tolerable in combination with carboplatin. The carboplatin/vorinostat doublet serves as a DNA-damaging/epigenetic modifier module to be combined in more complex regimens. Clinical trial information: NCT01281176.