Informing the Tolerability of Cancer Treatments Using Patient-Reported Outcome Measures: Summary of an FDA and Critical Path Institute Workshop.

The US Food and Drug Administration and the Critical Path Institute's Patient-Reported Outcome (PRO) Consortium convened a cosponsored workshop on the use of PRO measures to inform the assessment of safety and tolerability in cancer clinical trials. A broad array of international stakeholders involved in oncology drug development and PRO measurement science provided perspectives on the role of PRO measures to provide complementary clinical data on the symptomatic side effects of anticancer agents. Speakers and panelists explored the utility of information derived from existing and emerging PRO measures, focusing on the PRO version of the National Cancer Institute's Common Terminology Criteria for Adverse Events. Panelists and speakers discussed potential ways to improve the collection, analysis, and presentation of PRO data describing symptomatic adverse events to support drug development and better inform regulatory and treatment decisions. Workshop participants concluded the day with a discussion of possible approaches to the patient-reported assessment of an investigational drug's overall side effect burden as a potential clinical trial end point. The Food and Drug Administration reiterated its commitment to collaborate with international drug development stakeholders to identify rigorous methods to incorporate the patient perspective into the development of cancer therapeutics.

Adaptive phase 2/3 designs for oncology drug development - Time to hedge.

Randomized-controlled Phase 2 trials are routinely skipped in oncology drug development in favor of directly going to confirmatory Phase 3 after signal-detection post dose-finding in Phase 1. With improved standard-of-care, this speed-oriented aggressive approach is not sustainable. It is time to apply the state-of-art adaptive 2-in-1 Phase 2/3 designs to mitigate the risk of costly Phase 3 failures and allow a study to choose the optimal path to success.

Challenges to Using Big Data in Cancer.

Big data in healthcare can enable unprecedented understanding of diseases and their treatment, particularly in oncology. These data may include electronic health records, medical imaging, genomic sequencing, payor records, and data from pharmaceutical research, wearables, and medical devices. The ability to combine datasets and use data across many analyses is critical to the successful use of big data and is a concern for those who generate and use the data. Interoperability and data quality continue to be major challenges when working with different healthcare datasets. Mapping terminology across datasets, missing and incorrect data, and varying data structures make combining data an onerous and largely manual undertaking. Data privacy is another concern addressed by the Health Insurance Portability and Accountability Act, the Common Rule, and the General Data Protection Regulation. The use of big data is now included in the planning and activities of the FDA and the European Medicines Agency. The willingness of organizations to share data in a precompetitive fashion, agreements on data quality standards, and institution of universal and practical tenets on data privacy will be crucial to fully realizing the potential for big data in medicine.

Case Studies for Overcoming Challenges in Using Big Data in Cancer.

The analysis of big healthcare data has enormous potential as a tool for advancing oncology drug development and patient treatment, particularly in the context of precision medicine. However, there are challenges in organizing, sharing, integrating, and making these data readily accessible to the research community. This review presents five case studies illustrating various successful approaches to addressing such challenges. These efforts are CancerLinQ, the American Association for Cancer Research Project GENIE, Project Data Sphere, the National Cancer Institute Genomic Data Commons, and the Veterans Health Administration Clinical Data Initiative. Critical factors in the development of these systems include attention to the use of robust pipelines for data aggregation, common data models, data deidentification to enable multiple uses, integration of data collection into physician workflows, terminology standardization and attention to interoperability, extensive quality assurance and quality control activity, incorporation of multiple data types, and understanding how data resources can be best applied. By describing some of the emerging resources, we hope to inspire consideration of the secondary use of such data at the earliest possible step to ensure the proper sharing of data in order to generate insights that advance the understanding and the treatment of cancer.

A phase 1 trial of E7974 administered on day 1 of a 21-day cycle in patients with advanced solid tumors.

BACKGROUND: E7974, a synthetic analog of hemiasterlin, interacts with the tubulin molecule and overcomes resistance to other antitubulin drugs (taxanes and vinca alkaloids). METHODS: In a phase 1 study, E7974 was given intravenously over a 2- to 5-minute infusion on day 1 of every 21-day cycle. Adult patients with advanced refractory solid tumors who had adequate organ function and Eastern Cooperative Oncology Group performance status 0 to 2 were eligible for this study. A modified Fibonacci schema was used. The maximal tolerated dose (MTD) was the dose where <2 of 6 patients developed a dose-limiting toxicity (DLT). RESULTS: Twenty-eight patients (19 men and 9 women; median age, 64 years) treated at different cohort dose levels (0.18 mg/m(2) , 0.27 mg/m(2) , 0.36 mg/m(2) , 0.45 mg/m(2) , and 0.56 mg/m(2) ) received a total of 66 courses of E7974. The MTD was established at 0.45 mg/m(2) , where 1 of 6 patients experienced DLT (grade 4 febrile neutropenia). Of the 17 refractory colon cancer patients with a median of 3 prior treatments, stable disease was seen in 7 patients (41%). There were no tumor responses. Median progression-free survival was 1.2 months, and median overall survival was 6.7 months. In pharmacokinetic analysis, E7974 was characterized by a fast and moderately large distribution (37.95-147.93 L), slow clearance (2.23-7.15 L/h), and moderate to slow elimination (time to half-life, 10.4-30.5 hours). CONCLUSIONS: This study shows that E7974 once every 21-day cycle shows antitumor activity in patients with refractory solid tumors. The recommended phase 2 dose is 0.45 mg/m(2).

Assessment of added activity of an antitumor agent.

An unprecedented number of novel oncology drugs are under preclinical and clinical development, and nearly all are developed in combinations. With an over-reliance on biological hypotheses, there is less effort to establish single agent activity before initiating late clinical development. This may be contributing to a decreased success rate going from phase 1 to approval in the immunotherapy era. Growing evidence in clinical trial data shows that the treatment benefit from most approved combination therapies can be explained by the independent drug action model. Using this working model, we develop a simple index to measure the added antitumor activity of a new drug based on mean response duration, an endpoint that naturally combines both response status and duration information for all patients, which is shown to be highly predictive of clinical benefit of FDA-approved anti-PD-(L)1 immunotherapies. This index sheds light on challenges and opportunities in contemporary oncology drug development and provides a practical tool to assist with decision-making in early clinical trials.

Log-Rank Test vs MaxCombo and Difference in Restricted Mean Survival Time Tests for Comparing Survival Under Nonproportional Hazards in Immuno-oncology Trials: A Systematic Review and Meta-analysis.

Importance: The log-rank test is considered the criterion standard for comparing 2 survival curves in pivotal registrational trials. However, with novel immunotherapies that often violate the proportional hazards assumptions over time, log-rank can lose power and may fail to detect treatment benefit. The MaxCombo test, a combination of weighted log-rank tests, retains power under different types of nonproportional hazards. The difference in restricted mean survival time (dRMST) test is frequently proposed as an alternative to the log-rank under nonproportional hazard scenarios. Objective: To compare the log-rank with the MaxCombo and dRMST in immuno-oncology trials to evaluate their performance in practice. Data Sources: Comprehensive literature review using Google Scholar, PubMed, and other sources for randomized clinical trials published in peer-reviewed journals or presented at major clinical conferences before December 2019 assessing efficacy of anti-programmed cell death protein-1 or anti-programmed death/ligand 1 monoclonal antibodies. Study Selection: Pivotal studies with overall survival or progression-free survival as the primary or key secondary end point with a planned statistical comparison in the protocol. Sixty-three studies on anti-programmed cell death protein-1 or anti-programmed death/ligand 1 monoclonal antibodies used as monotherapy or in combination with other agents in 35 902 patients across multiple solid tumor types were identified. Data Extraction and Synthesis: Statistical comparisons (n = 150) were made between the 3 tests using the analysis populations as defined in the original protocol of each trial. Main Outcomes and Measures: Nominal significance based on a 2-sided .05-level test was used to evaluate concordance. Case studies featuring different types of nonproportional hazards were used to discuss more robust ways of characterizing treatment benefit instead of sole reliance on hazard ratios. Results: In this systematic review and meta-analysis of 63 studies including 35 902 patients, between the log-rank and MaxCombo, 135 of 150 comparisons (90%) were concordant; MaxCombo achieved nominal significance in 15 of 15 discordant cases, while log-rank did not. Several cases appeared to have clinically meaningful benefits that would not have been detected using log-rank. Between the log-rank and dRMST tests, 137 of 150 comparisons (91%) were concordant; log-rank was nominally significant in 5 of 13 cases, while dRMST was significant in 8 of 13. Among all 3 tests, 127 comparisons (85%) were concordant. Conclusions and Relevance: The findings of this review show that MaxCombo may provide a pragmatic alternative to log-rank when departure from proportional hazards is anticipated. Both tests resulted in the same statistical decision in most comparisons. Discordant studies had modest to meaningful improvements in treatment effect. The dRMST test provided no added sensitivity for detecting treatment differences over log-rank.

Tumor mutational burden predicts the efficacy of pembrolizumab monotherapy: a pan-tumor retrospective analysis of participants with advanced solid tumors.

BACKGROUND: Several studies have evaluated the relationship between tumor mutational burden (TMB) and outcomes of immune checkpoint inhibitors. In the phase II KEYNOTE-158 study of pembrolizumab monotherapy for previously treated recurrent or metastatic cancer, high TMB as assessed by the FoundationOne CDx was associated with an improved objective response rate (ORR). METHODS: We retrospectively assessed the relationship between TMB and efficacy in participants with previously treated advanced solid tumors enrolled in 12 trials that evaluated pembrolizumab monotherapy, including 3 randomized trials that compared pembrolizumab with chemotherapy. TMB was assessed in formalin-fixed, paraffin-embedded pretreatment tumor samples by whole-exome sequencing. High TMB was defined as ≥175 mutations/exome. Microsatellite instability (MSI) phenotype was based on whole-exome sequencing results. Programmed death ligand 1 (PD-L1) expression was assessed by immunohistochemistry. The primary end point was ORR assessed per RECIST V.1.1 by independent central review. Other end points included progression-free survival (PFS) assessed per RECIST V.1.1 by independent central review and overall survival (OS). RESULTS: Of the 2234 participants in the analysis, 1772 received pembrolizumab monotherapy and 462 received chemotherapy. Among the pembrolizumab-treated participants, ORR was 31.4% (95% CI 27.1 to 36.0) in the 433 participants with TMB ≥175 mutations/exome and 9.5% (95% CI 8.0 to 11.2) in the 1339 participants with TMB <175 mutations/exome. The association of TMB with ORR was observed regardless of PD-L1 expression and not driven by specific tumor types or participants with very high TMB or high MSI. In the 3 randomized controlled trials, TMB was associated with ORR (p≤0.016), PFS (p≤0.005), and OS (p≤0.029) of pembrolizumab but not of chemotherapy (p≥0.340, p≥0.643, and p≥0.174, respectively), and pembrolizumab improved efficacy versus chemotherapy in participants with TMB ≥175 mutations/exome. CONCLUSIONS: TMB ≥175 mutations/exome is associated with clinically meaningful improvement in the efficacy of pembrolizumab monotherapy and improved outcomes for pembrolizumab versus chemotherapy across a wide range of previously treated advanced solid tumor types. These data suggest TMB has broad clinical utility irrespective of tumor type, PD-L1 expression, or MSI status and support its use as a predictive biomarker for pembrolizumab monotherapy in participants with previously treated advanced solid tumors.

Proceedings From the ASCO/College of American Pathologists Immune Checkpoint Inhibitor Predictive Biomarker Summit.

PURPOSE: Immune checkpoint inhibition (ICI) therapy represents one of the great advances in the field of oncology, highlighted by the Nobel Prize in 2018. Multiple predictive biomarkers for ICI benefit have been proposed. These include assessment of programmed death ligand-1 expression by immunohistochemistry, and determination of mutational genotype (microsatellite instability or mismatch repair deficiency or tumor mutational burden) as a reflection of neoantigen expression. However, deployment of these assays has been challenging for oncologists and pathologists alike. METHODS: To address these issues, ASCO and the College of American Pathologists convened a virtual Predictive Factor Summit from September 14 to 15, 2021. Representatives from the academic community, US Food and Drug Administration, Centers for Medicare and Medicaid Services, National Institutes of Health, health insurance organizations, pharmaceutical companies, in vitro diagnostics manufacturers, and patient advocate organizations presented state-of-the-art predictive factors for ICI, associated problems, and possible solutions. RESULTS: The Summit provided an overview of the challenges and opportunities for improvement in assay execution, interpretation, and clinical applications of programmed death ligand-1, microsatellite instability-high or mismatch repair deficient, and tumor mutational burden-high for ICI therapies, as well as issues related to regulation, reimbursement, and next-generation ICI biomarker development. CONCLUSION: The Summit concluded with a plan to generate a joint ASCO/College of American Pathologists strategy for consideration of future research in each of these areas to improve tumor biomarker tests for ICI therapy.

A Biomarker-enriched, Randomized Phase II Trial of Adavosertib (AZD1775) Plus Paclitaxel and Carboplatin for Women with Platinum-sensitive TP53-mutant Ovarian Cancer.

PURPOSE: Preclinical studies show that adavosertib, a WEE1 kinase inhibitor, sensitizes TP53-mutant cells to chemotherapy. We hypothesized that adavosertib, plus chemotherapy, would enhance efficacy versus placebo in TP53-mutated ovarian cancer. PATIENTS AND METHODS: Following safety run-in, this double-blind phase II trial (NCT01357161) randomized women with TP53-mutated, platinum-sensitive ovarian cancer to oral adavosertib (225 mg twice daily for 2.5 days/21-day cycle) or placebo, plus carboplatin (AUC5) and paclitaxel (175 mg/m2), until disease progression or for six cycles. The primary endpoints were progression-free survival (PFS) by enhanced RECIST v1.1 [ePFS (volumetric)] and safety. Secondary/exploratory objectives included PFS by RECIST v1.1 (single dimension), objective response rate, overall survival, and analysis of tumor gene profile versus sensitivity to adavosertib. RESULTS: A total of 121 patients were randomized to adavosertib (A+C; n = 59) and placebo (P+C; n = 62) plus chemotherapy. Adding adavosertib to chemotherapy improved ePFS [median, 7.9 (95% confidence interval (CI), 6.9-9.9) vs. 7.3 months (5.6-8.2); HR 0.63 (95% CI, 0.38-1.06); two-sided P = 0.080], meeting the predefined significance threshold (P < 0.2). Clinical benefit was observed following A+C for patients with different TP53 mutation subtypes, identifying possible response biomarkers. An increase in adverse events was seen with A+C versus P+C: greatest for diarrhea (adavosertib 75%; placebo 37%), vomiting (63%; 27%), anemia (53%; 32%), and all grade ≥3 adverse events (78%; 65%). CONCLUSIONS: Establishing an optimal strategy for managing tolerability and identifying specific patient populations most likely to benefit from treatment may increase clinical benefit. Future studies should consider additional adavosertib doses within the chemotherapy treatment cycle and the potential for maintenance therapy.

Defining tumor resistance to PD-1 pathway blockade: recommendations from the first meeting of the SITC Immunotherapy Resistance Taskforce.

As the field of cancer immunotherapy continues to advance at a fast pace, treatment approaches and drug development are evolving rapidly to maximize patient benefit. New agents are commonly evaluated for activity in patients who had previously received a programmed death receptor 1 (PD-1)/programmed death-ligand 1 (PD-L1) inhibitor as standard of care or in an investigational study. However, because of the kinetics and patterns of response to PD-1/PD-L1 blockade, and the lack of consistency in the clinical definitions of resistance to therapy, the design of clinical trials of new agents and interpretation of results remains an important challenge. To address this unmet need, the Society for Immunotherapy of Cancer convened a multistakeholder taskforce-consisting of experts in cancer immunotherapy from academia, industry, and government-to generate consensus clinical definitions for resistance to PD-(L)1 inhibitors in three distinct scenarios: primary resistance, secondary resistance, and progression after treatment discontinuation. The taskforce generated consensus on several key issues such as the timeframes that delineate each type of resistance, the necessity for confirmatory scans, and identified caveats for each specific resistance classification. The goal of this effort is to provide guidance for clinical trial design and to support analyses of emerging molecular and cellular data surrounding mechanisms of resistance.

Pharmacokinetic/pharmacodynamic modeling and simulation of neutropenia during phase I development of liposome-entrapped paclitaxel.

PURPOSE: To evaluate the maximum tolerated dose (MTD), dose-limiting toxicities (DLT), and pharmacokinetics of liposome-entrapped paclitaxel easy-to-use (LEP-ETU) and to characterize the relationship between LEP-ETU concentrations and the time course of neutropenia in cancer patients. EXPERIMENTAL DESIGN: LEP-ETU was administered to 88 patients and 63 were evaluable for pharmacokinetic/pharmacodynamic (PK/PD) analysis following 1.5- and 3-h infusions every 3 weeks (q3w; dose range, 135-375 mg/m(2)). MTD was identified using a 3 + 3, up-and-down dose-finding algorithm. PK/PD modeling was done to describe the temporal relationship between paclitaxel concentrations and neutrophil count. Simulations assessed the influence of dose and schedule on neutropenia severity to help guide dose selection. RESULTS: The MTD of LEP-ETU was identified as 325 mg/m(2). DLTs occurring at 375 mg/m(2) consisted of febrile neutropenia and neuropathy. The C(max) and area under the plasma concentration-time curve of LEP-ETU were less than proportional with increasing dose. The PK/PD model showed that LEP-ETU inhibition of neutrophil proliferation was 9.1% per 10 mug/mL of total paclitaxel concentration. The incidence of grade 4 neutropenia increased from 33% to 42% across the dose range of 275 to 325 mg/m(2) q3w. For a dose of 110 mg/m(2) given weekly, grade 4 neutropenia was estimated to be 16% compared with 42% for the same total dose administered q3w. CONCLUSIONS: LEP-ETU can be administered safely at higher doses than Taxol. Modeling and simulation studies predict that 325 mg/m(2) LEP-ETU q3w provides acceptable neutropenic events relative to those observed at 175 mg/m(2) Taxol q3w. A 275 mg/m(2) dose may offer an improved therapeutic index.

Optimal two-stage designs for exploratory basket trials.

The primary goal of an exploratory oncology clinical trial is to identify an effective drug for further development. To account for tumor indication selection error, multiple tumor indications are often selected for simultaneous testing in a basket trial. In this article, we propose optimal and minimax two-stage basket trial designs for exploratory clinical trials. Inactive tumor indications are pruned in stage 1 and the active tumor indications are pooled at end of stage 2 to assess overall effectiveness of the test drug. The proposed designs explicitly control the type I and type II error rates with closed-form sample size formula. They can be viewed as a natural extension of Simon's optimal and minimax two-stage designs for single arm trials to multi-arm basket trials. A simulation study shows that the proposed design method has desirable operating characteristics as compared to other commonly used design methods for exploratory basket trials.

Correction: The topoisomerase I- and p53-binding protein topors is differentially expressed in normal and malignant human tissues and may function as a tumor suppressor.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Challenges with Novel Clinical Trial Designs: Master Protocols.

The 2018 Accelerating Anticancer Agent Development (AAADV) Workshop assembled a panel of experts for an in-depth discussion session to present "Challenges with Novel Clinical Trial Designs." This panel offered assessments of the challenges faced by industry, the FDA, investigators, institutional review boards, and patients. The panel focused on master protocols, which include umbrella trials, platform trials, and basket trials. Umbrella trials and platform trials share many commonalities, whereas basket trials are more distinct. Umbrella and platform trials are generally designed with multiple arms where patients of the same histology or other unifying characteristics are enrolled into different arms and multiple investigational agents are evaluated in a single protocol. In contrast, basket studies generally enroll patients with different tumor types based on the presence of a specific mutation or biomarker regardless of histology; these trials may include expansion cohorts. These novel designs offer the promise of expedited drug assessment and approval, but they also place new challenges on all the stakeholders involved in the drug development process. Only by identifying the challenges of these complex, innovative clinical trial designs and highlighting challenges from each perspective can we begin to address these challenges. The 2018 AAADV Workshop convened a panel of experts from relevant disciplines to highlight the challenges that are created by master protocols, and, where appropriate, offer strategies to address these challenges.

Seamless Designs: Current Practice and Considerations for Early-Phase Drug Development in Oncology.

Traditionally, drug development has evaluated dose, safety, activity, and comparative benefit in a sequence of phases using trial designs and endpoints specifically devised for each phase. Innovations in drug development seek to consolidate the phases and rapidly expand accrual with "seamless" trial designs. Although consolidation and rapid accrual may yield efficiencies, widespread use of seamless first-in-human (FiH) trials without careful consideration of objectives, statistical analysis plans, or trial oversight raises concerns. A working group formed by the National Cancer Institute convened to consider and discuss opportunities and challenges for such trials as well as encourage responsible use of these designs. We reviewed all abstracts presented at American Society of Clinical Oncology annual meetings from 2010 to 2017 for FiH trials enrolling at least 100 patients. We identified 1786 early-phase trials enrolling 57 559 adult patients. Fifty-one of the trials (2.9%) investigated 50 investigational new drugs, were seamless, and accounted for 14.6% of the total patients. The seamless trials included a median of 3 (range = 1-13) expansion cohorts. The overall risk of clinically significant treatment-related adverse events (grade 3-4) was 49.1% (range = 0.0-100%), and seven studies reported at least one toxic death. Rapid expansion of FiH trials may lead to earlier drug approval and corresponding widespread patient access to active therapeutics. Nevertheless, seamless designs must adhere to established ethical, scientific, and statistical standards. Protocols should include prospectively planned analyses of efficacy in disease- or biomarker-defined cohorts of sufficient rigor to support accelerated approval.

Identification of phosphorylation sites of TOPORS and a role for serine 98 in the regulation of ubiquitin but not SUMO E3 ligase activity.

TOPORS is the first example of a protein that possesses both ubiquitin and SUMO E3 ligase activity. The ubiquitination activity maps to a conserved RING domain in the N-terminal region of the protein, which is not required for sumoylation activity. Similar to other E3 ligases, it is likely that the ubiquitin and sumoylation activities of TOPORS are regulated by post-translational modifications. Therefore, we employed mass spectrometry to identify post-translational modifications of TOPORS. Several putative phosphorylated regions were identified in conserved regions of the protein. We investigated the role of phosphorylation of serine 98, which is adjacent to the RING domain, in both cells and in vitro. Mutation of serine 98 to aspartic acid resulted in an increase in the ubiquitin ligase activity of TOPORS both in cells and in vitro. In addition, this mutation increased the binding of TOPORS to the E2 enzyme UbcH5a both in vitro and in cells. Conversely, a phospho-deficient mutant (S98A) exhibited little change in ubiquitin ligase activity compared to wild-type TOPORS, both in cells and in vitro. Neither of the mutants affected the localization of TOPORS to punctate nuclear regions. In addition, neither mutant affected the SUMO ligase activity of TOPORS in cells or in vitro. Molecular modeling studies support a role for serine 98 in regulating TOPORS-E2 interactions. Our findings indicate that phosphorylation of serine 98 regulates the ubiquitin but not the SUMO ligase activity of TOPORS, consistent with a potential binary switch function for TOPORS in protein ubiquitination versus sumoylation.

Phase I and pharmacokinetic study of imatinib mesylate (Gleevec) and gemcitabine in patients with refractory solid tumors.

PURPOSE: Preclinical data shows improvements in response for the combination of imatinib mesylate (IM, Gleevec) and gemcitabine (GEM) therapy compared with GEM alone. Our goals were to determine the maximum tolerated dose of GEM and IM in combination, the pharmacokinetics of GEM in the absence and in the presence of IM, and IM pharmacokinetics in this combination. PATIENTS AND METHODS: Patients with refractory malignancy, intact intestinal absorption, measurable/evaluable disease, adequate organ function, Eastern Cooperative Oncology Group PS 0-2, and signed informed consent were eligible. Initially, treatment consisted of 600 mg/m2 of GEM (10 mg/m2/min) on days 1, 8, and 15, and 300 mg of IM daily every 28 days. Due to excessive toxicity, the schedule was altered to IM on days 1 to 5 and 8 to 12, and GEM on days 3 and 10 every 21 days. Two final cohorts received IM on days 1 to 5, 8 to 12, and 15 to 19. RESULTS: Fifty-four patients were treated. IM and GEM given daily at 500 to 600 mg/m2 on days 1, 8, and 15 produced frequent dose-limiting toxicities. With the modified scheduling, GEM given at 1,500 mg/m2/150 min was deliverable, along with 400 mg of IM, without dose-limiting toxicities. Three partial (laryngeal, renal, and mesothelioma) and two minor (renal and pancreatic) responses were noted at GEM doses of 450 to 1,500 mg/m2. Stable disease >24 weeks was seen in 17 patients. CA19-9 in 7 of 10 patients with pancreatic cancer was reduced by approximately 90%. IM did not significantly alter GEM pharmacokinetics. CONCLUSION: The addition of intermittently dosed IM to GEM at low to full dose was associated with broad antitumor activity and little increase in toxicity.

Elevated expression of ISG15 in tumor cells interferes with the ubiquitin/26S proteasome pathway.

IFN-stimulatory gene factor 15 (ISG15) is a ubiquitin-like protein, which is conjugated to many cellular proteins. However, its role in protein degradation is unclear. Here, we show that ISG15 is highly elevated and extensively conjugated to cellular proteins in many tumors and tumor cell lines. The increased levels of ISG15 in tumor cells were found to be associated with decreased levels of polyubiquitinated proteins. Specific knockdown of ISG15 expression using ISG15-specific small interfering RNA (siRNA) was shown to increase the levels of polyubiquitinated proteins, suggesting an antagonistic role of ISG15 in regulating ubiquitin-mediated protein turnover. Moreover, siRNA-mediated down-regulation of the major E2 for ISG15 (UbcH8), which blocked the formation of ISG15 protein conjugates, also increased the levels of polyubiquitinated proteins. Together, our results suggest that the ISG15 pathway, which is deregulated during tumorigenesis, negatively regulates the ubiquitin/proteasome pathway by interfering with protein polyubiquitination/degradation.

A 2-in-1 adaptive phase 2/3 design for expedited oncology drug development.

We propose an adaptive design that allows us to expand an ongoing Phase 2 trial into a Phase 3 trial to expedite a drug development program with fewer patients. Rather than the usual practice of increasing sample size with a less positive interim outcome, here we propose maintaining sample size with such a result and wait for fully mature data. The final Phase 2 data may be negative, may warrant a larger Phase 3 trial, or, in the extreme, could provide a definitively positive outcome. If the interim outcome is more positive, the trial continues to an originally planned larger sample size for a definitive Phase 3 evaluation. All patients from the study are used for inference regardless of the interim expansion decision. We show that no penalty needs to be paid in order to control the overall Type I error of the study, under a mild assumption that is expected to generally hold in practice. The proposed design may be considered an alternative approach to sample size adjustment for ongoing trials. As such, the use of an intermediate endpoint for adaptive decision is a unique feature of the design. A hypothetical example is provided for illustration purpose.