Stable disease is a valid end point in clinical trials

A multicenter phase Ia study of AbGn-107, a novel antibody-drug conjugate, in patients with advanced gastrointestinal cancer

AbGn-107 is an antibody-drug conjugate directed against AG-7 antigen, a Lewis A-like glycol-epitope expressed in a variety of gastrointestinal (GI) malignancies. Based on promising antitumor activity of AbGn-107 in both in vitro and in vivo preclinical studies, we performed a GI cancer-specific Phase I trial. Standard 3 + 3 dose escalation was used evaluating intravenous doses ranging from 0.1 mg/kg every 4 weeks to 1.0 mg/kg every 2 weeks. Key eligibility included chemo-refractory locally advanced, recurrent, or metastatic gastric, colorectal, pancreatic, or biliary cancer, with ECOG PS 0-1; positive AG-7 expression was not required during dose escalation phase. Patients were treated until disease progression or unacceptable toxicity, with tumor assessments every 8 weeks. Primary objectives included safety and determination of maximum tolerated dose; secondary objectives included efficacy defined by objective response rate. Thirty-nine patients were enrolled across seven dose levels during dose escalation phase. Based on safety profile and pharmacokinetic data, 1.0 mg/kg Q2W was selected as the dose schedule for cohort expansion phase, in which an additional seven patients were enrolled. Median number of lines of prior therapy was 3 (range 1-7). AbGn-107 was generally well-tolerated, with infections, cytopenias, hyponatremia, fatigue, abdominal pain, and diarrhea representing the most common grade 3 or higher treatment-emergent adverse events. One subject achieved a partial response, while 18 (46.2%) achieved a best response of stable disease. Disease control lasting > 6 months was observed in 6 subjects (13.0%), including 4 of 15 (26.7%) treated at the highest dose level. AbGn-107 showed a reasonable safety profile and modest clinical activity in this highly pretreated patient population. Further evaluation is required to assess the clinical validity of AG-7 as a suitable antigen for therapeutic targeting. Clinical Trial information: NCT02908451.

First-in-Human Study of OBI-999, a Globo H-Targeting Antibody-Drug Conjugate, in Patients With Advanced Solid Tumors

PURPOSE

OBI-999 is a novel antibody-drug conjugate comprising the Globo H-targeting antibody (OBI-888) linked to the cytotoxic payload monomethyl auristatin E. OBI-999 demonstrated excellent dose-dependent tumor growth inhibition in breast, gastric, and pancreatic cancer xenograft models as well as a lung cancer patient-derived xenograft model. We conducted a phase I study of OBI-999 monotherapy in patients with advanced cancer (ClinicalTrials.gov identifier: NCT04084366).

PATIENTS AND METHODS

OBI-999 was administered intravenously at doses of 0.4, 0.8, 1.2, and 1.6 mg/kg every 21 days as part of a 3 + 3 trial design. Primary end points were the incidence of dose-limiting toxicities and adverse events and determination of the maximum tolerated dose (MTD)/recommended phase II dose.

RESULTS

Fifteen adult patients were treated. OBI-999 was well tolerated up to 1.2 mg/kg, the maximum tolerated dose. The most common treatment-emergent adverse events were neutropenia and anemia. OBI-999 exhibited nonlinear pharmacokinetics at all doses, with lower clearance at higher doses. The three patients treated at the 1.6 mg/kg dose level developed grade 4 neutropenia during cycles 1 and 2. Five (33.3%) patients had stable disease (SD) including one patient with adenoid cystic carcinoma of the oropharynx with SD for 13 cycles and one patient with gastroesophageal junction adenocarcinoma with SD for eight cycles. OBI-999 was well tolerated; however, dose-dependent, noncumulative neutropenia was dose-limiting.

CONCLUSION

The recommended phase II dose was determined to be 1.2 mg/kg once every 3 weeks. A phase II cohort-expansion study is now enrolling patients with pancreatic, colorectal, and other cancers expressing high levels of Globo H.

Differences in sensitivity to new therapies between primary and metastatic breast cancer: A need to stratify the tumor response?

OBJECTIVE

We compared therapeutic response of Varlitinib + Capecitabine (VC) versus Lapatinib + Capecitabine (LC) in patients with human epidermal growth factor receptor 2-positive metastatic breast cancer after trastuzumab therapy by assessing changes in target lesion (TL) diameter and volume per location.

METHODS

We retrospectively analyzed the CT data of the ASLAN001-003 study (NCT02338245). We analyzed TL size and number at each location focusing on therapeutic response from baseline to Week 12. We used TL diameter and volume to conduct an inter-arm comparison of the response according to: RECIST 1.1; stratified per TL location and considering TLs independently. Multiple pairwise intra-arm comparisons of therapeutic responses were performed. Considering TL independently, weighted models were designed by adding weighted mean TL responses grouped by location.

RESULTS

We evaluated 42 patients (88 TL) and 35 patients (74 TL), respectively, at baseline and Week 12. We found reductions in breast TL burden in the VC arm compared to the LC arm (p = 0.002 (diameter), p < 0.001 (volume)). Responses and TL sizes at baseline were not correlated. Explained variabilities of volume change per TL location, patient and patient:TL interaction were 36%, 10% and 4% (VC), and 13%, 1% and 23%, (LC). A test of inter-arm difference of responses yielded p = 0.07 (diameter), and p < 0.001 (volume).

CONCLUSIONS

The therapeutic responses differed across tumors' locations; the magnitude of the differences of responses across the tumors' locations were drug-dependent. Stratified analysis of the response by tumor location improved drug comparisons and is a powerful tool to understand TL heterogeneity.

Phase 1 study of M2698, a p70S6K/AKT dual inhibitor, in patients with advanced cancer

BACKGROUND

The PI3K/AKT/mTOR (PAM) pathway is a key regulator of tumor therapy resistance. We investigated M2698, an oral p70S6K/AKT dual inhibitor, in patients with advanced cancer who failed standard therapies.

METHODS

M2698 was administered as monotherapy (escalation, 15-380 mg daily; food effect cohort, 240-320 mg daily) and combined with trastuzumab or tamoxifen.

RESULTS

Overall, 101 patients were treated (M2698, n = 62; M2698/trastuzumab, n = 13; M2698/tamoxifen, n = 26). Patients were predominantly aged < 65 years, were female, had performance status 1 and were heavily pretreated. There was a dose- and concentration-dependent inhibition of pS6 levels in peripheral blood mononuclear cells and tumor tissue. M2698 was well tolerated; the most common treatment-emergent adverse events were gastrointestinal, abnormal dreams and fatigue (serious, attributed to M2698: monotherapy, 8.1%; M2698/trastuzumab, 7.7%; M2698/tamoxifen, 11.5% of patients). The recommended phase 2 doses of M2698 were 240 mg QD (monotherapy), 160 mg QD (M2698/trastuzumab) and 160 mg QD/240 mg intermittent regimen (M2698/tamoxifen). In the monotherapy cohort, 27.4% of patients had stable disease at 12 weeks; no objective response was noted. The median progression-free survival (PFS) durations in patients with PAM pathway alterations with and without confounding markers (KRAS, EGFR, AKT2) were 1.4 months and 2.8 months, respectively. Two patients with breast cancer (M2698/trastuzumab, n = 1; M2698/tamoxifen, n = 1) had partial response; their PFS durations were 31 months and 2.7 months, respectively.

CONCLUSIONS

M2698 was well tolerated. Combined with trastuzumab or tamoxifen, M2698 demonstrated antitumor activity in patients with advanced breast cancer resistant to multiple standard therapies, suggesting that it could overcome treatment resistance. Trial registration ClinicalTrials.gov, NCT01971515. Registered October 23, 2013.

Therapeutic Targeting of Protein Kinase CK2 Gene Expression in Feline Oral Squamous Cell Carcinoma: A Naturally Occurring Large-Animal Model of Head and Neck Cancer

Protein kinase CK2 (CK2) is a highly promising target for cancer therapy, and anti-CK2 gene expression therapy has shown effectiveness in rodent models of human head and neck cancer (HNC). To date, there has been no large-animal model of cancer in which to further explore anti-CK2 therapies. Feline oral squamous cell carcinoma (FOSCC) has been proposed as a large-animal model for human HNC, and we have previously shown that CK2 is a rational target in FOSCC. Here we have tested the hypothesis that a novel tenfibgen-coated tumor-specific nanocapsule carrying RNA interference (RNAi) oligonucleotides targeting feline CK2α and CK2α' (TBG-RNAi-fCK2αα') would be safe in cats with FOSCC; assessment of target inhibition and tumor response were secondary aims. Nine cats were enrolled and treated at two dose levels in a 3+3 escalation. Cats received a total of six treatments with TBG-RNAi-fCK2αα'. Pre- and posttreatment, tumor and normal oral mucosa biopsies were collected to assess CK2 expression, using immunohistochemistry (IHC) preparations evaluated by light microscopy. Toxicity and tumor response were assessed on the basis of standard criteria. The most common adverse events were grade 1 or 2 weight loss and anorexia. Grade 3 tissue necrosis was seen in association with tumor response in one cat, asymptomatic grade 4 elevations in aspartate transaminase and creatine phosphokinase in one cat, and asymptomatic grade 3 hypokalemia in one cat. Of six cats with evaluable biopsies, two had a reduction in CK2 IHC score in tumors after treatment. Four cats had progressive disease during the study period, three had stable disease, one had partial response, and response could not be evaluated in one cat. We conclude that the drug appeared safe and that there is some evidence of efficacy in FOSCC. Further investigation regarding dosing, schedule, target modulation, toxicity, and efficacy in a larger group of cats is warranted and may inform future clinical studies in human head and neck cancer.

Changes of lung tumour volume on CT - prediction of the reliability of assessments

Background

For oncological evaluations, quantitative radiology gives clinicians significant insight into patients’ response to therapy. In regard to the Response Evaluation Criteria in Solid Tumours (RECIST), the classification of disease evolution partly consists in applying thresholds to the measurement of the relative change of tumour. In the case of tumour volumetry, response thresholds have not yet been established. This study proposes and validates a model for calculating thresholds for the detection of minimal tumour change when using the volume of pulmonary lesions on CT as imaging biomarker.

Methods

Our work is based on the reliability analysis of tumour volume measurements documented by the Quantitative Imaging Biomarker Alliance. Statistics of measurements were entered into a multi-parametric mathematical model of the relative changes derived from the Geary-Hinkley transformation. The consistency of the model was tested by comparing modelled thresholds against Monte Carlo simulations of tumour volume measurements with additive random error. The model has been validated by repeating measurements on real patient follow ups.

Results

For unchanged tumour volume, relying on a normal distribution of error, the agreement between model and simulations featured a type I error of 5.25 %. Thus, we established that a threshold of 35 % of volume reduction corresponds to a partial response (PR) and a 55 % volume increase corresponds to progressive disease (PD). Changes between −35 and +55 % are categorized as stable disease (SD). Tested on real clinical data, 97.1 % [95.7; 98.0] of assessments fall into the range of variability predicted by our model of confidence interval.

Conclusions

Our study indicates that the Geary Hinkley model, using published statistics, is appropriate to predict response thresholds for the volume of pulmonary lesions on CT.

Combining AKT inhibition with chloroquine and gefitinib prevents compensatory autophagy and induces cell death in EGFR mutated NSCLC cells

Although non-small cell lung cancer (NSCLC) patients with EGFR mutation positive (EGFR M+) tumors initially respond well to EGFR tyrosine kinase inhibitor (TKI) monotherapy, the responses are usually incomplete. In this study we show that AKT inhibition, most importantly AKT2 inhibition, synergises with EGFR TKI inhibition to increase cell killing in EGFR M+ NSCLC cells. However, our data also suggest that the synergistic pro-apoptotic effects may be stunted due to a prosurvival autophagy response induced by AKT inhibition. Consequently, inhibiting autophagy with chloroquine significantly enhanced tumor cell death induced by gefitinib and AKT inhibitors in EGFR M+ cells in vitro, and produced greater tumor shrinkage in EGFR M+ xenografts in vivo. Together, our findings suggest that adding chloroquine to EGFR and AKT inhibition has the potential to improve tumor responses in EGFR M+ NSCLC, and that selective targeting of AKT2 may provide a new treatment option in NSCLC.

Outcomes and endpoints in trials of cancer treatment: the past, present, and future

Cancer treatment should allow patients to live better or longer lives, and ideally, both. Trial endpoints should show clinically meaningful improvements in patient survival or quality of life. Alternative endpoints such as progression-free survival, disease-free survival, and objective response rate have been used to identify benefit earlier, but their true validity as surrogate endpoints is controversial. In this Review we discuss the measurement, assessment, and benefits and limitations of trial endpoints in use for cancer treatment. Many stakeholders are affected, including regulatory agencies, industry partners, clinicians, and most importantly, patients. In an accompanying Review, reflections from individual stakeholders are incorporated into a discussion of what the future holds for clinical trial endpoints and design.

Efficacy and safety of retreatment with ipilimumab in patients with pretreated advanced melanoma who progressed after initially achieving disease control

PURPOSE

Ipilimumab is a fully human monoclonal antibody against cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) that has been shown to improve survival in patients with pretreated, advanced melanoma in a phase III trial. Some patients in this study who initially responded to ipilimumab treatment but later progressed were eligible for retreatment with their original randomized regimen. Here, outcomes for these patients concerning baseline characteristics, best overall response, and disease control rate are assessed and considered with respect to the overall study population.

EXPERIMENTAL DESIGN

In the phase III study, 676 pretreated patients were randomly allocated to treatment with ipilimumab 3 mg/kg plus gp100 vaccine, ipilimumab 3 mg/kg plus placebo, or gp100 vaccine alone. Of these patients, 32 had a partial or complete objective response or stable disease after treatment and met the eligibility criteria for retreatment, although a total of 40 patients were retreated.

RESULTS

Best overall response rates (complete responses plus partial responses) for 31 retreatment-eligible patients in the ipilimumab plus gp100 and ipilimumab plus placebo groups were 3 of 23 (13.0%) and 3 of 8 (37.5%), respectively, and disease control rates were 65.2% and 75.0%. No new types of toxicities occurred during retreatment and most events were mild-to-moderate.

CONCLUSION

Ipilimumab provided durable objective responses and/or stable disease in qualifying patients who received retreatment upon disease progression with a similar toxicity profile to that seen during their original treatment regimen.

Why RECIST works and why it should stay--counterpoint

Assessing that the efficacy of a cancer therapeutic is an integral part of its path to regulatory approval, we review the history that led to our current assessment method, Response Evaluation Criteria in Solid Tumors (RECIST). We describe the efforts of Moertel and Hanley to standardize response assessments in lymphoid malignancies and how this was adapted in the World Health Organization (WHO) criteria. Two decades later, RECIST was advanced to streamline WHO and improve its reproducibility. We describe the ways in which thresholds established by Moertel and Hanley to provide accuracy and reproducibility evolved to become measures of efficacy and why they have been valuable. While we recognize RECIST is far from perfect-in need of modification as a measure of efficacy for some agents and in some diseases-for the majority of solid tumors, it is very valuable. We argue that over time, the efficacy thresholds established by WHO and then RECIST have proved their worth, and we summarize 10 years of U.S. Food and Drug Administration (FDA) approvals in solid tumors to support our position that current RECIST thresholds should be retained.

Issues surrounding clinical trial endpoints in solid malignancies with a focus on metastatic non-small cell lung cancer

Relative to best supportive care alone, cytotoxic chemotherapy has an established role in prolonging overall survival (OS) in patients with or without previous treatment for metastatic non-small cell lung cancer (NSCLC). OS has been the principal endpoint influencing regulatory decisions regarding targeted therapies for metastatic NSCLC, including the vascular endothelial growth factor monoclonal antibody bevacizumab in the frontline setting and the epidermal growth factor receptor tyrosine kinase inhibitors gefitinib and erlotinib in patients after prior treatment. Progression-free survival (PFS), another common endpoint in oncology clinical trials, has been discussed as a potential surrogate for OS in metastatic NSCLC. A number of phase III clinical trials of investigational targeted agents for treatment of metastatic NSCLC are ongoing, with OS designated as the primary endpoint in some cases and PFS in others. Both endpoints have been developed largely to evaluate outcomes in unselected populations in which a fraction of patients are anticipated to derive significant benefit. New approaches are being considered for the evaluation of targeted agents. Recent high profile trials have been designed to assess PFS using a randomized discontinuation design and disease control rate after 8 weeks of treatment. With a series of recent advances toward increasingly personalized biomarker-directed anticancer therapies, the appropriateness of the traditional regulatory approach has been questioned.

Tumor response and progression-free survival as potential surrogate endpoints for overall survival in extensive stage small-cell lung cancer: findings on the basis of North Central Cancer Treatment Group trials

BACKGROUND

The authors investigated the putative surrogate endpoints of best response, complete response (CR), confirmed response, and progression-free survival (PFS) for associations with overall survival (OS), and as possible surrogate endpoints for OS.

METHODS

Individual patient data from 870 untreated extensive stage small-cell lung cancer patients participating in 6 single-arm (274 patients) and 3 randomized trials (596 patients) were pooled. Patient-level associations between putative surrogate endpoints and OS were assessed by Cox models using landmark analyses. Trial-level surrogacy of putative surrogate endpoints were assessed by the association of treatment effects on OS and individual putative surrogate endpoints. Trial-level surrogacy measures included: R(2) from weighted least squares regression model, Spearman correlation coefficient, and R(2) from bivariate survival model (Copula R(2) ).

RESULTS

Median OS and PFS were 9.6 (95% confidence interval [CI], 9.1-10.0) and 5.5 (95% CI, 5.2-5.9) months, respectively; best response, CR, and confirmed response rates were 44%, 22%, and 34%, respectively. Patient-level associations showed that PFS status at 4 months was a strong predictor of subsequent survival (hazard ratio [HR], 0.42; 95% CI, 0.35-0.51; concordance index 0.63; P < .01), with 6-month PFS being the strongest (HR, 0.41; 95% CI, 0.35-0.49; concordance index, 0.66, P < .01). At the trial level, PFS showed the highest level of surrogacy for OS (weighted least squares R(2) = 0.79; Copula R(2) = 0.80), explaining 79% of the variance in OS. Tumor response endpoints showed lower surrogacy levels (weighted least squares R(2) ≤0.48).

CONCLUSIONS

PFS was strongly associated with OS at both the patient and trial levels. PFS also shows promise as a potential surrogate for OS, but further validation is needed using data from a larger number of randomized phase 3 trials.