RECIST 1.1 - Standardisation and disease-specific adaptations: Perspectives from the RECIST Working Group

High frequency of radiological differential responses with poly(ADP-Ribose) polymerase (PARP) inhibitor therapy

Despite impressive clinical activity in patients with germline BRCA1 and BRCA2 (BRCA1/2) mutant cancers, antitumor responses to poly(ADP-Ribose) polymerase (PARP) inhibitors are variable. We set out to assess the rate of intrapatient radiological differential responses (RDR) to PARP inhibitors, its correlation with patient outcomes, and the identification of factors associated with RDR. We retrospectively reviewed all patients with advanced cancers from five early phase PARP inhibitor monotherapy trials. 113 patients (ovarian cancers 57.5%; breast cancers 23.9%) were included in this retrospective study; 46 (40.7%) patients developed RDR on PARP inhibitor monotherapy. We identified two patterns of RDR: early RDR (1st or 2nd on-treatment scans) in 69.6% of patients, and late RDR (penultimate or final scans) in 30.4% of patients. Early RDR was associated with shorter time to progression (TTP) (225 vs 367 days, HR:0.59, 95%CI 0.36-0.98; p=0.04) and overall survival (OS) (499 vs 857 days; HR:0.47, 95%CI 0.27-0.82, p=0.006). Seventy-nine (69.9%) patients had known germline BRCA1/2 mutations; 49.4% of these BRCA1/2 mutation carriers developed RDR versus 20.6% of patients with unknown or wildtype BRCA1/2 status. Harboring germline BRCA1/2 mutations was independently predictive for RDR (RR:2.93, 95% CI 1.08-7.90, p=0.03). Patients with germline BRCA1 mutations had worse TTP and OS than BRCA2 mutation carriers (212 vs 406 days, HR:0.58, 95% CI 0.36-0.94, p=0.023 and 515 vs 937 days; HR:0.49, 95% CI 0.29-0.83; p=0.007). RDR with PARP inhibitors are frequent, particularly in germline BRCA1/2 mutation carriers. These findings have clinical implications for patient outcomes and may reflect underlying intrapatient genomic heterogeneity.

Reviewing RECIST in the Era of Prolonged and Targeted Therapy

Accurate assessment of disease response is the foundation of therapeutic trails, which is why the Response Evaluation Criteria in Solid Tumors (RECIST) serve as an international standard that investigators can utilize when examining patient outcomes. Nine years after the initial RECIST criteria were released, an update, RECIST 1.1, was published to improve on the initial criteria and address technologic advancements in imaging. Since then, advancements in both standard clinical and trial practices, combined with improvements in our understanding of cancer biology, have resulted in the identification of a number of limitations of the current RECIST 1.1, either in lack of clear guidance with regard to its best application or in potential benefit of capturing imaging-related data beyond standard categorical response details. As several of these situations reflect the consequences of prolonged control of metastatic disease by using targeted therapies, thoracic oncology has generated many of the key scenarios requiring elucidation and/or improvements. This article specifically examines current controversies in the interpretation and/or optimal utilization of RECIST 1.1, focusing on examples from thoracic oncology, and makes proposals, where possible, on how best to address these issues. These situations include addressing central nervous system versus extra-central nervous system response and progression, depth of response, oligoprogression versus polyprogression, continuation of systemic therapy after use of a local ablative therapy, and the impact of fluctuations in measurements bridging partial response and stable disease categories during prolonged therapy.

Tumor response assessment: comparison between unstructured free text reporting in routine clinical workflow and computer-aided evaluation based on RECIST 1.1 criteria

PURPOSE

Standardized computer-aided tumor response assessment is common in clinical trials. In contrast, unstructured free text reporting (UFTR) is common in daily routine. Therefore, this study aimed to discern and quantify differences between UFTR and computer-aided standardized tumor response evaluation based on RECIST 1.1 criteria (RECIST), serving as gold standard, in clinical workflow.

METHODS

One-hundred consecutive patients with cancer eligible for RECIST 1.1 evaluation, who received five follow-up CTs of the trunk, were retrospectively included. All UFTRs were assigned to RECIST response categories [complete response, partial response (PR), stable disease (SD), progressive disease (PD)]. All CTs were re-evaluated using dedicated software (mint lesion™) applying RECIST 1.1. The accordance in tumor response ratings was analyzed using Cohen's kappa.

RESULTS

At the first follow-up, 47 cases were rated differently with an SD underrepresentation and a PR and PD overrepresentation in UFTR. In the subsequent follow-ups, categorical differences were seen in 38, 44, 37, and 44%. Accordance between UFTR and RECIST was fair to moderate (Cohen's kappa: 0.356, 0.477, 0.390, 0.475, 0.376; always p < 0.001). Differences were mainly caused by the rating of even small tumor burden changes as PD or PR in UFTR or by comparison to the most recent prior CT scan in UFTR instead of comparison to nadir or baseline.

CONCLUSIONS

Significant differences in tumor response ratings were detected comparing UFTR and computer-aided standardized evaluation based on RECIST 1.1. Thus, standardized reporting should be implemented in daily routine workflow.

A phase 1/1B trial of ADI-PEG 20 plus nab-paclitaxel and gemcitabine in patients with advanced pancreatic adenocarcinoma

BACKGROUND

ADI-PEG 20 is a pegylated form of the arginine-depleting enzyme arginine deiminase. Normal cells synthesize arginine with the enzyme argininosuccinate synthetase (ASS1); ADI-PEG 20 selectively targets malignant cells, which lack ASS1.

METHODS

A single-arm, nonrandomized, open-label, phase 1/1B, standard 3 + 3 dose escalation with an expansion cohort of 9 patients at the recommended phase 2 dose (RP2D) was conducted. Patients who had metastatic pancreatic cancer, up to 1 line of prior treatment (the dose-escalation cohort) or no prior treatment (the expansion cohort), and an Eastern Cooperative Oncology Group performance status of 0 to 1 were included. Patients received both gemcitabine (1000 mg/m² ) and nab-paclitaxel (125 mg/m² ) for 3 of 4 weeks and intramuscular ADI-PEG 20 at 18 mg/m² weekly (cohort 1) or at 36 mg/m² weekly (cohort 2 and the expansion cohort).The primary endpoint was to determine the maximum tolerated dose and RP2D of ADI-PEG 20 in combination with nab-paclitaxel and gemcitabine.

RESULTS

Eighteen patients were enrolled. No dose-limiting toxicities (DLTs) were observed in cohort 1; cohort 2 was expanded to 6 patients because of 1 DLT occurrence (a grade 3 elevation in bilirubin, aspartate aminotransferase, and alanine aminotransferase). The most frequent adverse events (AEs) of any grade were neutropenia, thrombocytopenia, leukopenia, anemia, peripheral neuropathy, and fatigue; all 18 patients experienced grade 3/4 AEs. The most frequent grade 3/4 toxicities, regardless of the relation with any drugs, included neutropenia (12 patients or 67%), leukopenia (10 patients or 56%), anemia (8 patients or 44%), and lymphopenia (6 patients or 33%). The RP2D for ADI-PEG 20 was 36 mg/m² weekly in combination with standard-dose gemcitabine and nab-paclitaxel. The overall response rate among patients treated at the RP2D in the first-line setting was 45.5% (5 of 11).The median progression-free survival time for these patients treated at the RP2D was 6.1 months (95% confidence interval, 5.3-11.2 months), and the median overall survival time was 11.3 months (95% confidence interval, 6.7 months to not reached).

CONCLUSIONS

ADI-PEG 20 was well tolerated in combination with gemcitabine and nab-paclitaxel. Activity was observed in previously treated and untreated patients with advanced pancreatic cancer and in patients with ASS1-deficient and -proficient tumors. Cancer 2017;123:4556-4565. © 2017 American Cancer Society.

Response assessment after induction chemotherapy for head and neck squamous cell carcinoma: From physical examination to modern imaging techniques and beyond

Significant correlations between the response to induction chemotherapy and success of subsequent radiotherapy have been reported and suggest that the response to induction chemotherapy is able to predict a response to radiotherapy. Therefore, induction chemotherapy may be used to tailor the treatment plan to the individual patient with head and neck cancer: following the planned subsequent (chemo)radiation schedule, planning a radiation dose boost, or reassessing the modality of treatment (eg, upfront surgery). Findings from reported trials suggest room for improvement in clinical response assessment after induction chemotherapy, but an optimal method has yet to be identified. Historically, indices of treatment efficacy in solid tumors have been based solely on systematic assessment of tumor size. However, functional imaging (eg, fluorodeoxyglucose‐positron emission tomography (FDG‐PET) potentially provides an earlier indication of response to treatment than conventional imaging techniques. More advanced imaging techniques are still in an exploratory phase and are not ready for use in clinical practice.

Limits of radiomic-based entropy as a surrogate of tumor heterogeneity: ROI-area, acquisition protocol and tissue site exert substantial influence

Entropy is a promising quantitative imaging biomarker for characterizing cancer imaging phenotype. Entropy has been associated with tumor gene expression, tumor metabolism, tumor stage, patient prognosis, and treatment response. Our hypothesis states that tumor-specific biomarkers such as entropy should be correlated between synchronous metastases. Therefore, a significant proportion of the variance of entropy should be attributed to the malignant process. We analyzed 112 patients with matched/paired synchronous metastases (SM#1 and SM#2) prospectively enrolled in the MOSCATO-01 clinical trial. Imaging features were extracted from Regions Of Interest (ROI) delineated on CT-scan using TexRAD software. We showed that synchronous metastasis entropy was correlated across 5 Spatial Scale Filters: Spearman's Rho ranged between 0.41 and 0.59 (P = 0.0001, Bonferroni correction). Multivariate linear analysis revealed that entropy in SM#1 is significantly associated with (i) primary tumor type; (ii) entropy in SM#2 (same malignant process); (iii) ROI area size; (iv) metastasis site; and (v) entropy in the psoas muscle (reference tissue). Entropy was a logarithmic function of ROI area in normal control tissues (aorta, psoas) and in mathematical models (P < 0.01). We concluded that entropy is a tumor-specific metric only if confounding factors are corrected.

iRECIST: guidelines for response criteria for use in trials testing immunotherapeutics

Tumours respond differently to immunotherapies compared with chemotherapeutic drugs, raising questions about the assessment of changes in tumour burden-a mainstay of evaluation of cancer therapeutics that provides key information about objective response and disease progression. A consensus guideline-iRECIST-was developed by the RECIST working group for the use of modified Response Evaluation Criteria in Solid Tumours (RECIST version 1.1) in cancer immunotherapy trials, to ensure consistent design and data collection, facilitate the ongoing collection of trial data, and ultimate validation of the guideline. This guideline describes a standard approach to solid tumour measurements and definitions for objective change in tumour size for use in trials in which an immunotherapy is used. Additionally, it defines the minimum datapoints required from future trials and those currently in development to facilitate the compilation of a data warehouse to use to later validate iRECIST. An unprecedented number of trials have been done, initiated, or are planned to test new immune modulators for cancer therapy using a variety of modified response criteria. This guideline will allow consistent conduct, interpretation, and analysis of trials of immunotherapies.