Darrel P. Cohen

Primary and Secondary Kinase Genotypes Correlate With the Biological and Clinical Activity of Sunitinib in Imatinib-Resistant Gastrointestinal Stromal Tumor

PURPOSE Most gastrointestinal stromal tumors (GISTs) harbor mutant KIT or platelet-derived growth factor receptor alpha (PDGFRA) kinases, which are imatinib targets. Sunitinib, which targets KIT, PDGFRs, and several other kinases, has demonstrated efficacy in patients with GIST after they experience imatinib failure. We evaluated the impact of primary and secondary kinase genotype on sunitinib activity. PATIENTS AND METHODS Tumor responses were assessed radiologically in a phase I/II trial of sunitinib in 97 patients with metastatic, imatinib-resistant/intolerant GIST. KIT/PDGFRA mutational status was determined for 78 patients by using tumor specimens obtained before and after prior imatinib therapy. Kinase mutants were biochemically profiled for sunitinib and imatinib sensitivity. RESULTS Clinical benefit (partial response or stable disease for > or = 6 months) with sunitinib was observed for the three most common primary GIST genotypes: KIT exon 9 (58%), KIT exon 11 (34%), and wild-type KIT/PDGFRA (56%). Progression-free survival (PFS) was significantly longer for patients with primary KIT exon 9 mutations (P = .0005) or with a wild-type genotype (P = .0356) than for those with KIT exon 11 mutations. The same pattern was observed for overall survival (OS). PFS and OS were longer for patients with secondary KIT exon 13 or 14 mutations (which involve the KIT-adenosine triphosphate binding pocket) than for those with exon 17 or 18 mutations (which involve the KIT activation loop). Biochemical profiling studies confirmed the clinical results. CONCLUSION The clinical activity of sunitinib after imatinib failure is significantly influenced by both primary and secondary mutations in the predominant pathogenic kinases, which has implications for optimization of the treatment of patients with GIST.

Hypertension as a biomarker of efficacy in patients with metastatic renal cell carcinoma treated with sunitinib

Background Hypertension (HTN) is an on-target effect of the vascular endothelial growth factor pathway inhibitor, sunitinib. We evaluated the association of sunitinib-induced HTN with antitumor efficacy and HTN-associated adverse events in patients with metastatic renal cell carcinoma. Methods This retrospective analysis included pooled efficacy (n = 544) and safety (n = 4917) data from four studies of patients with metastatic renal cell carcinoma who were treated with sunitinib 50 mg/d administered on a 4-week-on 2-week-off schedule (schedule 4/2). Blood pressure (BP) was measured in the clinic on days 1 and 28 of each 6-week cycle. Progression-free survival (PFS) and overall survival (OS) were estimated using Kaplan–Meier methods; hazard ratios (HRs) for survival were also estimated by a Cox proportional hazards models using HTN as a time-dependent covariate. Efficacy outcomes were compared between patients with and without HTN (maximum systolic BP [SBP] ≥140 mm Hg or diastolic BP [DBP] ≥90 mm Hg). Adverse events were also compared between patients with and without HTN (mean SBP ≥140 mm Hg or mean DBP ≥90 mm Hg). All P values were two-sided. Results Patients with metastatic renal cell carcinoma and sunitinib-induced HTN defined by maximum SBP had better outcomes than those without treatment-induced HTN (objective response rate: 54.8% vs 8.7%; median PFS: 12.5 months, 95% confidence interval [CI] = 10.9 to 13.7 vs 2.5 months, 95% CI = 2.3 to 3.8 months; and OS: 30.9 months, 95% CI = 27.9 to 33.7 vs 7.2 months, 95% CI = 5.6 to 10.7 months; P < .001 for all). Similar results were obtained when comparing patients with vs without sunitinib-induced HTN defined by maximum DBP. In a Cox proportional hazards model using HTN as a time-dependent covariate, PFS (HR of disease progression or death = .603, 95% CI = .451 to .805; P < .001) and OS (HR of death = .332, 95% CI = .252 to .436; P < .001) were improved in patients with treatment-induced HTN defined by maximum SBP; OS (HR of death = .585, 95% CI = .463 to .740; P < .001) was improved in patients with treatment-induced HTN defined by maximum DBP, but PFS was not. Few any-cause cardiovascular, cerebrovascular, ocular, and renal adverse events were observed. Rates of adverse events were similar between patients with and without HTN defined by mean SBP; however, hypertensive patients had somewhat more renal adverse events (5% vs 3%; P = .013). Conclusions In patients with metastatic renal cell carcinoma, sunitinib-associated HTN is associated with improved clinical outcomes without clinically significant increases in HTN-associated adverse events, supporting its viability as an efficacy biomarker.

Clinical evaluation of continuous daily dosing of sunitinib malate in patients with advanced gastrointestinal stromal tumour after imatinib failure

AIMS To assess the antitumour activity, safety, pharmacokinetics and pharmacodynamics of continuous daily sunitinib dosing in patients with imatinib-resistant/intolerant gastrointestinal stromal tumour (GIST) and to assess morning dosing versus evening dosing. PATIENTS AND METHODS In this open-label phase II study, patients were randomised to receive morning or evening dosing of sunitinib 37.5mg/day. The primary end-point was clinical benefit rate (CBR; percent complete responses+partial responses [PRs]+stable disease [SD] 24 weeks). Secondary end-points included progression-free survival (PFS), overall survival (OS), safety, pharmacokinetic parameters and plasma biomarker levels. RESULTS Sixty of 61 planned patients received treatment (30 per dosing group); 26 completed the study. Overall, the CBR was 53% (95% exact CI, 40-66): eight patients (13%) achieved objective PRs; 24 (40%) achieved SD 24 weeks. Median PFS was 34 weeks (95% CI, 24-49); median OS was 107 weeks (95% CI, 72 - not yet calculable). Most adverse events (AEs) were of grade 1 or 2 in severity, and were manageable through dose modification or standard interventions. No new AEs were apparent compared with the approved intermittent dosing schedule. Antitumour activity and safety were generally similar with morning and evening dosing. Continuous daily sunitinib dosing achieved and sustained effective drug concentrations without additional accumulation across cycles. Decreases from baseline in plasma levels of soluble KIT after 20 and 24 weeks of dosing correlated with longer OS. CONCLUSION For patients with imatinib-resistant/intolerant GIST, continuous daily sunitinib dosing appears to be an active alternative dosing strategy with acceptable safety.

Clinical benefit of continuing ALK inhibition with crizotinib beyond initial disease progression in patients with advanced ALK-positive NSCLC

BACKGROUND Crizotinib is approved to treat advanced ALK-positive non-small-cell lung cancer (NSCLC), but most patients ultimately develop progressive disease (PD). We investigated whether continuing ALK inhibition with crizotinib beyond PD (CBPD) is clinically beneficial and attempted to identify clinicopathologic characteristics associated with patients who experience clinical benefit. PATIENTS AND METHODS Patients with advanced ALK-positive NSCLC enrolled in two ongoing multicenter, single-arm trials who developed RECIST-defined PD were allowed to continue crizotinib if they were deriving ongoing clinical benefit. In the present retrospective analysis, continuation of CBPD was defined as >3 weeks of crizotinib treatment after PD documentation. Patients who had PD as best response to initial crizotinib treatment were excluded. Baseline and post-progression characteristics, sites of PD, and overall survival (OS) were compared in patients who continued CBPD versus those who did not. The impact of continuing CBPD on OS after adjusting for potential confounding factors was assessed. RESULTS Among 194 crizotinib-treated patients with RECIST-defined PD, 120 (62%) continued CBPD. A significantly higher proportion of patients who continued CBPD than patients who did not had an ECOG performance status (PS) of 0/1 at PD (96% versus 82%; P=0.02). CBPD patients had significantly longer OS from the time of PD [median 16.4 versus 3.9 months; hazards ratio (HR) 0.27, 95% confidence interval (CI): 0.17-0.42; P<0.0001] and from the time of initial crizotinib treatment (median 29.6 versus 10.8 months; HR 0.30, 95% CI: 0.19-0.46; P<0.0001). The multiple-covariate Cox regression analysis revealed that CBPD remained significantly associated with improved OS after adjusting for relevant factors. CONCLUSIONS Patients who continued CBPD were more likely to have good ECOG PS (0/1) at the time of PD. Continuing ALK inhibition with crizotinib after PD may provide survival benefit to patients with advanced ALK-positive NSCLC.

Molecular Target Modulation, Imaging, and Clinical Evaluation of Gastrointestinal Stromal Tumor Patients Treated with Sunitinib Malate after Imatinib Failure

Purpose: To evaluate sunitinib activity and potential cellular and molecular correlates in gastrointestinal stromal tumor (GIST) patients after imatinib failure, in addition to assessing the safety and pharmacokinetics (PK) of different dose schedules. Experimental Design: In this open-label, dose-ranging, phase I/II study, 97 patients with metastatic imatinib-resistant/intolerant GIST received sunitinib at doses of 25, 50, or 75 mg/d on one of three schedules. Serial tumor imaging was done using computed tomography and [18F]fluoro-2-deoxy-d-glucose positron emission tomography scanning. PK and cell proliferation and KIT phosphorylation status in tumor biopsies were also analyzed. Results: Clinical benefit was observed in 52 patients (54%: 7 objective partial responses, 45 stable disease ≥6 months). Decreased tumor glycolytic activity was shown in most patients within 7 days of starting sunitinib using [18F]fluoro-2-deoxy-d-glucose positron emission tomography. Sunitinib treatment was associated with reduced tumor cell proliferation by >25% in 52% of cases analyzed and reduced levels of phospho-KIT in tumor biopsies (indicating target modulation). The recommended dose schedule was 50 mg/d for 4 weeks followed by 2 weeks off treatment. On the 50-mg dose across all schedules, 79% of PK-evaluable patients achieved total drug trough concentrations above the target concentration (50 ng/mL) within 14 days of dosing. In addition, adverse events were generally mild to moderate in severity. Conclusion: Cellular and molecular analyses showed that sunitinib clinical activity is associated with inhibition of KIT in GIST following imatinib failure, illustrating the rational approach used to develop a therapy aimed at the underlying oncogenic signaling pathway aberrancy. (Clin Cancer Res 2009;15(18):5902–9)

Complete Longitudinal Analyses of the Randomized, Placebo-controlled, Phase III Trial of Sunitinib in Patients with Gastrointestinal Stromal Tumor Following Imatinib Failure

Purpose: To analyze final long-term survival and clinical outcomes from the randomized phase III study of sunitinib in gastrointestinal stromal tumor patients after imatinib failure; to assess correlative angiogenesis biomarkers with patient outcomes. Experimental Design: Blinded sunitinib or placebo was given daily on a 4-week-on/2-week-off treatment schedule. Placebo-assigned patients could cross over to sunitinib at disease progression/study unblinding. Overall survival (OS) was analyzed using conventional statistical methods and the rank-preserving structural failure time (RPSFT) method to explore cross-over impact. Circulating levels of angiogenesis biomarkers were analyzed. Results: In total, 243 patients were randomized to receive sunitinib and 118 to placebo, 103 of whom crossed over to open-label sunitinib. Conventional statistical analysis showed that OS converged in the sunitinib and placebo arms (median 72.7 vs. 64.9 weeks; HR, 0.876; P = 0.306) as expected, given the cross-over design. RPSFT analysis estimated median OS for placebo of 39.0 weeks (HR, 0.505, 95% CI, 0.262–1.134; P = 0.306). No new safety concerns emerged with extended sunitinib treatment. No consistent associations were found between the pharmacodynamics of angiogenesis-related plasma proteins during sunitinib treatment and clinical outcome. Conclusions: The cross-over design provided evidence of sunitinib clinical benefit based on prolonged time to tumor progression during the double-blind phase of this trial. As expected, following cross-over, there was no statistical difference in OS. RPSFT analysis modeled the absence of cross-over, estimating a substantial sunitinib OS benefit relative to placebo. Long-term sunitinib treatment was tolerated without new adverse events. Clin Cancer Res; 18(11); 3170–9. ©2012 AACR.

Hypertension as a potential biomarker of efficacy in patients with gastrointestinal stromal tumor treated with sunitinib

BACKGROUND Reliable biomarkers of sunitinib response in gastrointestinal stromal tumor (GIST) are lacking. Hypertension (HTN), an on-target class effect of vascular endothelial growth factor signaling-pathway inhibitors, has been shown to correlate with clinical outcome in advanced renal cell carcinoma treated with sunitinib. PATIENTS AND METHODS This retrospective analysis examined correlations between sunitinib-associated HTN and antitumor efficacy (N = 319) and safety (N = 1565) across three advanced GIST studies. Blood pressure (BP) was measured on days 1 and 28 of each treatment cycle at a minimum. Time-to-event endpoints were estimated using Kaplan-Meier methods, and patient subgroups with and without HTN (maximum systolic BP ≥ 140 mmHg and/or diastolic BP ≥ 90 mmHg) were compared using Cox proportional hazards models. Landmark analyses evaluated associations between early HTN and efficacy endpoints. Adverse events (AEs) were compared between groups. RESULTS Sunitinib-associated HTN correlated with improved objective response rates, time to tumor progression, progression-free survival, and overall survival. Almost all benefits remained significant in multivariate and landmark analyses. Overall incidences of HTN-related AEs were low and similar between groups; incidences of cardiovascular AEs were somewhat higher in patients with HTN. CONCLUSION Sunitinib-associated HTN appeared to correlate with improved clinical outcomes in GIST, while incidences of HTN-associated AEs were generally low and manageable.

Sunitinib-associated hypertension and neutropenia as efficacy biomarkers in metastatic renal cell carcinoma patients

Background:Metastatic renal cell carcinoma (mRCC) prognostic models may be improved by incorporating treatment-induced toxicities.Methods:In sunitinib-treated mRCC patients (N=770), baseline prognostic factors and treatment-induced toxicities (hypertension (systolic blood pressure ⩾140 mm Hg), neutropenia (grade ⩾2), thrombocytopenia (grade ⩾2), hand–foot syndrome (grade >0), and asthenia/fatigue (grade >0)) were analysed in multivariate analyses of progression-free survival (PFS) and overall survival (OS) end points.Results:On-treatment neutropenia and hypertension were associated with longer PFS (P=0.0276 and P<0.0001, respectively) and OS (P=0.0014 and P<0.0001, respectively), independent of baseline prognostic factors, including International Metastatic Renal Cell Carcinoma Database Consortium (IMDC) criteria. By 12-week landmark analysis, neutropenia was significantly associated with longer PFS and OS (P=0.013 and P=0.0122, respectively) and hypertension or hand–foot syndrome with longer OS (P=0.0036 and P=0.0218, respectively). The concordance index was 0.65 (95% CI: 0.63−0.67) for IMDC classification alone and 0.72 (95% CI: 0.70−0.74) when combined with hypertension and neutropenia. Considering hypertension and neutropenia (developing both vs neither) changed IMDC-predicted median OS in each IMDC risk group (favourable: 45.3 vs 19.5 months; intermediate: 32.5 vs 8.0 months; poor: 21.1 vs 4.8 months).Conclusions:On-treatment neutropenia and hypertension are independent biomarkers of sunitinib efficacy and may add prognostic accuracy to the IMDC model.

Pre-clinical evaluation of SN-38 and novel camptothecin analogs against human chronic B-cell lymphocytic leukemia lymphocytes

The topoisomerase I inhibitor camptothecin and its analogs have potent activity against a wide range of solid tumors and several hematologic malignancies. Previous studies with these compounds using the MTT metabolic inhibition assay have shown significant cytotoxicity against lymphocytes from patients with chronic B-cell lymphocytic leukemia (B-CLL). Yet the water soluble analogue, topotecan, which was inhibitory at > 1 microM in vitro, had no clinical activity in vivo. In the present study, we evaluated the in vitro cytotoxicities of SN-38, the active form of irinotecan, and two newer water soluble camptothecin derivatives 10,11-methylenedioxy-20(S)-camptothecin glycinate (MDCG) and 7-chloromethyl-10,11-methylenedioxy-20(S)-camptothecin glycinate (CMMDCG). These two glycinate esters are prodrugs for 10,11-methylenedioxy-20(S)-camptothecin (MDC) and 7-chloromethyl-10,11-methylenedioxy-20(S)-camptothecin (CMMDC), respectively. Effects on cellular metabolism, induction of apoptosis, and overall cell survival were used to evaluate chemosensitivity. We report that the relative cytotoxic potency for these compounds is MDC > or = CMMDC > or = SN-38 >> TPT > CPT-11, where MDC, CMMDC, and SN-38 were over an order of magnitude more cytotoxic than TPT and CPT-11. We also investigated potential mechanisms underlying the unexpected cytotoxicity of these camptothecin derivatives in B-CLL cells that are known to be arrested in G0/G1 of the cell cycle, and found that this class of compounds inhibited [3H]uridine incorporation. We therefore postulate that the inhibition of RNA rather than DNA synthesis may be responsible for the observed cytotoxicity in non-cycling B-CLL cells.

A Phase I Study of Eniluracil/5-FU in Combination with Radiation Therapy for Potentially Resectable and/or Unresectable Cancer of the Pancreas and Distal Biliary Tract

Purpose: Eniluracil is an effective inactivator of dihydropyrimidine dehydrogenase (DPD). It allows for oral dosing of 5-fluorouracil (5-FU), which may potentially improve the antitumor activity of 5-FU when delivered concurrently with radiotherapy while avoiding the inconvenience and morbidity of continuous infusion (CI) 5-FU. We addressed the safety of oral eniluracil/5-FU combined with radiation therapy and determined the profile of dose-limiting toxicities and recommended Phase II dose (RPTD) in patients with pancreatic and hepatobiliary cancers. Methods and Materials: Patients with resectable or locally advanced pancreatic and biliary cancer received eniluracil (starting at 6.0 mg/m2 q12h)/5-FU (starting at 0.6 mg/m2 q12h). Eniluracil/5-FU were given concurrently with preoperative radiation to 4500 cGy followed by 540 cGy by reduced fields. Surgery was considered 4 weeks after completion of therapy. Results: Thirteen patients were enrolled. Chemoradiotherapy was completed in all patients. The MTD was not reached and, thus, the RPTD of eniluracil/5-FU was determined to be 10 mg/m2 q12h/1 mg/m2 q12h. Two patients with locally advanced disease had a 30–45 percent cross-sectional tumor reduction, one of which underwent margin-negative resection. Two of 5 patients with pancreatic cancer, and 1 of 3 patients with cholangiocarcinoma, with underwent exploratory surgery had margin-negative resections. One patient had a pathologic complete response (pCR). Patient 5-FU plasma exposure increased slightly from Day 8 to Day 31. Conclusion: Preoperative chemoradiation with oral eniluracil/5-FU is feasible, well tolerated, and potentially effective in the neoadjuvant setting. Further investigation of oral fluoropyrimidines as radiosensitizers for pancreaticobiliary malignancies is warranted.