Everolimus Concentration in Saliva to Predict Stomatitis: A Feasibility Study in Patients with Cancer

BACKGROUND

Most patients with cancer treated with everolimus experience stomatitis, which seriously affects the quality of life. The salivary concentrations of everolimus may predict the incidence and severity of stomatitis. The authors aimed to examine whether it was feasible to quantify the everolimus concentration in saliva and subsequently use it to predict stomatitis.

METHODS

Saliva and whole blood samples were taken from patients with cancer, who were treated with everolimus in the dosage of either 10 mg once a day or 5 mg twice a day. Everolimus concentrations in saliva samples were measured by liquid chromatography-tandem mass spectrometry. A published population pharmacokinetic model was extended with the everolimus concentration in saliva to assess any association between everolimus in the blood and saliva. Subsequently, the association between the occurrence of stomatitis and the everolimus concentration in saliva was studied.

RESULTS

Eleven patients were included in this study; saliva samples were available from 10 patients, including 3 patients with low-grade stomatitis. Everolimus concentrations were more than 100-fold lower in saliva than in whole blood (accumulation ratio 0.00801 and relative standard error 32.5%). Interindividual variability (67.7%) and residual unexplained variability (84.0%) were high. The salivary concentration of everolimus tended to be higher in patients with stomatitis, 1 hour postdose ( P = 0.14).

CONCLUSIONS

Quantification of the everolimus concentration in saliva was feasible and revealed a nonsignificant correlation between everolimus concentration in the saliva and the occurrence of stomatitis. If future research proves this relationship to be significant, the everolimus concentration in the saliva may be used as an early predictor of stomatitis without invasive sampling. Thereby, in patients with high salivary everolimus concentrations, precautions can be taken to decrease the incidence and severity of stomatitis.

Longitudinal nonlinear mixed effects modeling of EGFR mutations in ctDNA as predictor of disease progression in treatment of EGFR-mutant non-small cell lung cancer

Correlations between increasing concentrations of circulating tumor DNA (ctDNA) in plasma and disease progression have been shown. A nonlinear mixed effects model to describe the dynamics of epidermal growth factor receptor (EGFR) ctDNA data from patients with non-small cell lung cancer (NSCLC) combined with a parametric survival model were developed to evaluate the ability of these modeling techniques to describe ctDNA data. Repeated ctDNA measurements on L858R, exon19del, and T790M mutants were available from 54 patients with EGFR mutated NSCLC treated with erlotinib or gefitinib. Different dynamic models were tested to describe the longitudinal ctDNA concentrations of the driver and resistance mutations. Subsequently, a parametric time-to-event model for progression-free survival (PFS) was developed. Predicted L858R, exon19del, and T790M concentrations were used to evaluate their value as predictor for disease progression. The ctDNA dynamics were best described by a model consisting of a zero-order increase and first-order elimination (19.7/day, 95% confidence interval [CI] 14.9-23.6/day) of ctDNA concentrations. In addition, time-dependent development of resistance (5.0 × 10^-4 , 95% CI 2.0 × 10^-4 -7.0 × 10^-4 /day) was included in the final model. Relative change in L858R and exon19del concentrations from baseline was identified as most significant predictor of disease progression (p = 0.001). The dynamic model for L858R, exon19del, and T790M concentrations in ctDNA and time-to-event model adequately described the observed concentrations and PFS data in our clinical cohort. In addition, it was shown that nonlinear mixed effects modeling is a valuable method for the analysis of longitudinal and heterogeneous biomarker datasets obtained from clinical practice.

Precision Dosing of Targeted Therapies Is Ready for Prime Time

Fixed dosing of oral targeted therapies is inadequate in the era of precision medicine. Personalized dosing, based on pharmacokinetic (PK) exposure, known as therapeutic drug monitoring (TDM), is rational and supported by increasing evidence. The purpose of this perspective is to discuss whether randomized studies are needed to confirm the clinical value of precision dosing in oncology. PK-based dose adjustments are routinely made for many drugs and are recommended by health authorities, for example, for patients with renal impairment or for drug-drug interaction management strategies. Personalized dosing simply extrapolates this paradigm from selected patient populations to each individual patient with suboptimal exposure, irrespective of the underlying cause. If it has been demonstrated that exposure is related to a relevant clinical outcome, such as efficacy or toxicity, and that exposure can be optimized by PK-guided dosing, it could be logically assumed that PK-guided dosing would result in better treatment outcomes without the need for randomized confirmatory trials. We propose a path forward to demonstrate the clinical relevance of individualized dosing of molecularly-targeted anticancer drugs.

Intra-Tumoral Pharmacokinetics of Pazopanib in Combination with Radiotherapy in Patients with Non-Metastatic Soft-Tissue Sarcoma

There is a lack of understanding whether plasma levels of anticancer drugs (such as pazopanib) correlate with intra-tumoral levels and whether the plasma compartment is the best surrogate for pharmacokinetic and pharmacodynamic evaluation. Therefore, we aimed to quantify pazopanib concentrations in tumor tissue, to assess the correlation between tumor concentrations and plasma concentrations and between tumor concentrations and efficacy. In this clinical trial, non-metastatic STS patients were treated with neo-adjuvant concurrent radiotherapy and pazopanib. Plasma samples and tumor biopsies were collected, and pazopanib concentrations were measured using liquid chromatography-tandem mass spectrometry. Twenty-four evaluable patients were included. The median pazopanib tumor concentration was 19.2 µg/g (range 0.149-200 µg/g). A modest correlation was found between tumor concentrations and plasma levels of pazopanib (ρ = 0.41, p = 0.049). No correlation was found between tumor concentrations and percentage of viable tumor cells (p > 0.05); however, a trend towards less viable tumor cells in patients with high pazopanib concentrations in tumor tissue was observed in a categorical analysis. Possible explanations for the lack of correlation might be heterogeneity of the tumors and timing of the biopsy procedure.

Savolitinib ± Osimertinib in Japanese Patients with Advanced Solid Malignancies or EGFRm NSCLC: Ph1b TATTON Part C

Background

Preliminary data suggest that combining savolitinib, a potent and highly selective MET-tyrosine kinase inhibitor (TKI), with osimertinib, a third-generation, irreversible, oral epidermal growth factor receptor-TKI (EGFR-TKI), may overcome MET-based resistance to EGFR-TKIs.

Objective

To investigate the safety and tolerability of savolitinib in Japanese patients with advanced solid malignancies.

Patients and Methods

In Part C of the phase Ib, multi-arm, open-label, multicenter TATTON study, two cohorts of Japanese adult patients were evaluated across six study centers in Japan. Patients with advanced solid malignancies received oral savolitinib monotherapy 400 mg once daily (qd), escalating to 600 mg; patients with advanced EGFR mutation-positive (EGFRm) non-small-cell lung carcinoma (NSCLC) who progressed on prior EGFR-TKI received oral osimertinib 80 mg+savolitinib 300/400/600 mg qd combination therapy. Primary endpoints: safety/tolerability of savolitinib±osimertinib, and maximum tolerated dose(s) (MTD) definition.

Results

Seventeen patients received monotherapy; 12 received combination. Dose-limiting toxicities (DLTs): with monotherapy, 400 mg, none reported; 600 mg, n = 3/9 evaluable patients (33%) reported DLTs (grade 3 and 4 alanine aminotransferase and aspartate transaminase increased, and grade 4 drug-induced liver injury). With combination: 400 mg, 1/6 (17%) reported DLTs (grade 2 fatigue, nausea, and myalgia); 300 mg, none reported; 600 mg, 3/4 (75%) reported DLTs (grade 2 pyrexia, grade 3 skin reaction, and anaphylactic shock). Grade ≥3 adverse events were reported in 41% of patients receiving monotherapy and 33% receiving combination. TATTON is no longer recruiting patients.

Conclusions

The MTD of savolitinib was 400 mg qd in both cohorts. Data demonstrate an acceptable safety profile for savolitinib alone, or with osimertinib.

Trial registration: Clinicaltrials.gov; NCT02143466; 21 May 2014.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11523-021-00806-5.

For patients with epidermal growth factor receptor mutation-positive (EGFRm) non-small cell lung cancer (NSCLC), EGFR tyrosine kinase inhibitors, like osimertinib, are the standard treatment. However, for most patients, these treatments eventually stop working, as tumors develop resistance to them. Early studies suggest that combining osimertinib with savolitinib can overcome this resistance. We report Part C of the four-part TATTON study, in which two groups of Japanese adult patients received treatment. One group received savolitinib 400 mg once daily, then 600 mg. The other group received osimertinib 80 mg with savolitinib 300/400/600 mg once daily. The main objective of the study was to determine the maximum dose of savolitinib that patients could receive (maximum tolerated dose) and to monitor the safety of the combination. Overall, 17 patients received savolitinib alone and 12 received the combination. The maximum tolerated dose of savolitinib was found to be 400 mg once daily in both groups of patients. The data demonstrated that savolitinib had acceptable safety outcomes either alone, or in combination with osimertinib.

Parent and Metabolite Concentration-QT Modeling to Evaluate QT-Interval Prolongation at Savolitinib Therapeutic Doses

Savolitinib is an oral, potent, and highly selective MET-tyrosine kinase inhibitor under investigation in various tumor types. A thorough QT study evaluated effects on QT interval after a 600-mg single savolitinib dose in healthy subjects. We report exposure-response (E-R) modeling from this study to characterize the effects of savolitinib and its metabolites, M2 and M3, on QTc changes. In a novel application, in vitro potencies against hERG current provided mechanistic support to model the metabolites' effects. The hERG IC50 estimates (95% CI) were 25.8 (22.2-29.9) and 22.6 (14.7-34.6) μM for parent and M2, respectively. The E-R was described by both linear and E_max models, with exposure captured by an active moiety that consisted of savolitinib and M2 concentrations, weighted by the hERG IC50 ratio (1.14). The maximal increase in ΔΔQTcF and EC50 estimates (95% CI) was 18.5 (9.2-27.7) ms and 5709 (2889-8529) nM, respectively. Ignoring M2 contribution resulted in under prediction of QTcF prolongation in the hypothetical case of inhibited M2 clearance; at 300 mg C_max, the mean (90% CI) of ∆∆QTcF was 9.0 (5.7-12.6) and 5.9 (2.9-8.9) ms using the hERG-informed and parent-only linear models, respectively. Simulations in normal setting confirmed modest QTcF prolongation with 600 mg, but not 300 mg. Using the linear model, the mean (90% CI) maximum ΔΔQTcF were 12.3 (8.6-16.2) and 5.5 (2.6-8.5) ms for 600 and 300 mg, respectively. Further clinical studies will monitor cardiac safety to assess the clinical significance of QT-interval prolongation with savolitinib.

A phase III trial of capivasertib and abiraterone versus placebo and abiraterone in patients with de novo metastatic hormone-sensitive prostate cancer characterized by PTEN deficiency (CAPItello-281)

TPS178

Background: In metastatic hormone-sensitive prostate cancer (mHSPC), abiraterone combined with androgen deprivation therapy (ADT) is highly effective in improving patient outcomes. However, around 20% of patients progress to castration-resistant disease within 12 months of treatment; these patients have shorter survival and limited treatment options. Aberrant activation of the PI3K/AKT pathway, predominately due to PTEN loss, is common in prostate cancer, especially in later-stage disease. The androgen receptor signaling and AKT pathway are reciprocally cross-regulated such as that inhibition of one leads to upregulation of the other. Therefore, combining abiraterone therapy with AKT inhibition may be beneficial in patients with mHSPC who have PTEN deficiency. In preclinical studies, capivasertib, a selective oral pan-AKT inhibitor, inhibited proliferation of models of hormone-sensitive and castration-resistant prostate cancer with PTEN loss. The results of the IPATential150 phase 3 study (NCT03072238) demonstrated that another oral AKT inhibitor, ipatasertib, prolonged radiographic progression-free survival (rPFS) when combined with abiraterone compared with placebo plus abiraterone in metastatic castration-resistant prostate cancer, particularly among patients with PTEN loss. CAPItello-281 (NCT04493853) is a global, multicenter, phase 3 trial to evaluate capivasertib in combination with abiraterone, on a background of ADT, as a treatment for de novo mHSPC patients with PTEN-deficient tumors. Methods: Eligible patients for this double-blind, randomized trial are men aged 18 years or older with confirmed newly diagnosed previously untreated metastatic hormone-sensitive prostate adenocarcinoma with immunohistochemically confirmed PTEN deficiency and Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1. Following screening, approximately 1000 patients will be randomized 1:1 to receive either capivasertib (400 mg) or placebo (twice daily; 4 days on, 3 days off) in combination with abiraterone (1000 mg once daily) and ADT until radiographic progression or intolerable toxicity. The primary endpoint is rPFS. Secondary endpoints include overall survival, time to start of first subsequent therapy or death, symptomatic skeletal event-free survival, time to pain progression and safety profile. Enrolment started in July 2020. Acknowledgments: We thank Julia Grigorieva, PhD, of Oxford PharmaGenesis, Philadelphia, USA, for providing medical writing assistance. Funding: The CAPItello-281 trial is funded and overseen by AstraZeneca. Clinical trial information: NCT04493853.

A phase I study of capivasertib in combination with abiraterone acetate in patients with metastatic castration-resistant prostate cancer

85

Background: Androgen receptor (AR) targeting therapies prolong survival of patients with metastatic castration-resistant prostate cancer (mCRPC); however, in many cases, resistance develops, resulting in disease progression. Activation of the PI3K/AKT/mTOR signaling pathway is common in mCRPC and contributes to resistance, mostly due to loss of PTEN, which occurs in 40–60% of patients. Preclinical studies have demonstrated reciprocal regulation between the AR and PI3K/AKT/mTOR pathways and significant anti-tumor activity when both pathways are inhibited, particularly in models with PTEN-loss. Thus, a rationale exists to inhibit both pathways in mCRPC patients. We report interim results of a phase 1 multicohort study (NCT04087174) to confirm the acceptable dose of capivasertib, a potent, selective pan-AKT inhibitor in combination with the androgen synthesis inhibitor abiraterone acetate (AA) in mCRPC patients. Methods: Patients who had received at least one prior systemic therapy (chemotherapy or novel hormonal agent) for mCRPC were given AA (1000 mg, once daily) with capivasertib (400 mg, twice daily, 4 days on/3 days off) until unacceptable toxicity or disease progression. Dose-limiting toxicity in the first 28 days of treatment and adverse events were recorded. Results: 15 patients, median age 67 (range 49–82) years, were recruited in the USA and Spain. Twelve patients had received prior chemotherapy; 7 had two or more prior lines. Seven patients had received prior AA and 10 had received prior enzalutamide. No dose-limiting toxicities were recorded. Eight patients reported at least one grade ≥ 3 adverse event (AE). Grade ≥ 3 AEs in 7 patients were related to capivasertib: allergic reaction to medication, asthenia, type 2 diabetes mellitus, diarrhea and fatigue were each reported in 1 patient, maculopapular rash − in 2 patients, both hypokalemia and acquired Fanconi syndrome − in 1 patient. Acute kidney injury was reported in 4 patients but was not considered related to capivasertib. The most common AEs of any grade related to capivasertib were: diarrhea, 6/15 patients (40%); maculopapular rash, 5/15 (33%); fatigue, 4/15 (27%); hyperglycemia/type 2 diabetes mellitus, 4/15 (27%); nausea, 3/15 (20%); hypokalemia, 2/15 (13%); hypophosphatemia, 2/15 (13%). Capivasertib was discontinued in 4/15 patients (27%) due to AEs. Between initial screening and day 29 of treatment, 5 patients had reduced (> 20%) PSA levels, with 3 patients showing sustained falls in PSA over 12 weeks. Conclusions: In this phase 1 study combined capivasertib and AA exhibits an acceptable safety and tolerability profile. Further data on the clinical efficacy and safety of the combination are being collected in the phase 3 CAPItello-281 trial. Acknowledgments: We thank Adam Errington, PhD, of Oxford PharmaGenesis, for medical writing assistance. Funding: This trial is funded by AstraZeneca. Clinical trial information: NCT04087174.

Monitoring of EGFR mutations in circulating tumor DNA of non-small cell lung cancer patients treated with EGFR inhibitors

PURPOSE

We studied EGFR mutations in circulating tumor DNA (ctDNA) and explored their role in predicting the progression-free survival (PFS) of non-small cell lung cancer (NSCLC) patients treated with erlotinib or gefitinib.

METHODS

The L858R, T790M mutations and exon 19 deletions were quantified in plasma using digital droplet polymerase chain reaction (ddPCR). The dynamics of ctDNA mutations over time and relationships with PFS were explored.

RESULTS

In total, 249 plasma samples (1-13 per patient) were available from 68 NSCLC patients. The T790M and L858R or exon 19 deletion were found in the ctDNA of 49 and 56% patients, respectively. The median (range) concentration in these samples were 7.3 (5.1-3688.7), 11.7 (5.1-12,393.3) and 27.9 (5.9-2896.7) copies/mL, respectively. Using local polynomial regression, the number of copies of EGFR mutations per mL increased several months prior to progression on standard response evaluation.

CONCLUSION

This change was more pronounced for the driver mutations than for the resistance mutations. In conclusion, quantification of EGFR mutations in plasma ctDNA was predictive of treatment outcomes in NSCLC patients. In particular, an increase in driver mutation copy number could predict disease progression.

A Randomized, Double-Blind, Placebo- and Positive-Controlled, Three-Way Crossover Study in Healthy Participants to Investigate the Effect of Savolitinib on the QTc Interval

Savolitinib (AZD6094, HMPL-504, volitinib) is an oral, bioavailable, selective MET-tyrosine kinase inhibitor. This randomized, double-blind, 3-way, crossover phase 1 study of savolitinib versus moxifloxacin (positive control) and placebo-evaluated effects on the QT interval after a single savolitinib dose. Healthy non-Japanese men were randomized to 1 of 6 treatment sequences, receiving single doses of savolitinib 600 mg, moxifloxacin 400 mg, and placebo. The primary end point was time-matched, placebo-adjusted change from baseline in the QT interval corrected for the time between corresponding points on 2 consecutive R waves on electrocardiogram (RR) by the Fridericia formula (ΔΔQTcF). Secondary end points included 12-lead electrocardiogram (ECG) variables, pharmacokinetics, and safety. All 3 treatment periods were completed by 44 of 45 participants (98%). Baseline demographics were balanced across treatment groups. After a single savolitinib 600-mg dose, the highest least-squares mean ΔΔQTcF of 12 milliseconds was observed 5 hours postdose. Upper limits of the 2-sided 90% confidence interval for ΔΔQTcF exceeded 10 milliseconds (the prespecified International Council for Harmonisation limit) 3-6 hours postsavolitinib but otherwise remained less than the threshold. Savolitinib showed no additional effect on PR, QRS, QT, or RR intervals. A positive ΔΔQTcF signal from the moxifloxacin group confirmed study validity. Savolitinib was well tolerated, with a low incidence of adverse events. In this thorough QT/QTc study, QTcF prolongation was observed with a single savolitinib 600-mg dose. ECG monitoring will be implemented in ongoing and future studies of savolitinib to assess the clinical relevance of the observed QT changes from this study.

A phase Ib study of the highly selective MET-TKI savolitinib plus gefitinib in patients with EGFR-mutated, MET-amplified advanced non-small-cell lung cancer

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) are recommended first-line treatments in EGFR-mutated (EGFRm) non-small-cell lung cancer (NSCLC). However, acquired resistance (e.g. MET amplification) is frequently observed. Savolitinib (volitinib, HMPL-504, AZD6094) is an oral, potent, and highly selective MET-TKI. In this phase Ib, open-label, multicenter study, we enrolled Chinese patients with EGFRm advanced NSCLC, whose disease progressed following prior EGFR-TKI treatment. In the safety run-in, patients received savolitinib 600 or 800 mg plus gefitinib 250 mg orally once daily, and dose-limiting toxicities were recorded. In the expansion phase, patients with MET amplification received savolitinib plus gefitinib. The primary endpoint was safety/tolerability. Secondary endpoints included antitumor activity. Thirteen patients were enrolled in the safety phase (median age 52 years, 46% female) and 51 enrolled in the expansion phase (median age 61 years, 67% female). No dose-limiting toxicities were reported in either dose group during the safety run-in. Adverse events of grade ≥ 3 in the safety run-in and expansion phases (n = 57) were reported in 21 (37%) patients. The most frequently reported adverse events (all grades) were: vomiting (n = 26, 46%), nausea (n = 23, 40%), increased aspartate aminotransferase (n = 22, 39%). Of four deaths, none were treatment-related. The objective response rates in EGFR T790M-negative, -positive, and -unknown patients were 52% (12/23), 9% (2/23), and 40% (2/5), respectively. Savolitinib 600 mg plus gefitinib 250 mg once daily had an acceptable safety profile and demonstrated promising antitumor activity in EGFRm, MET-amplified advanced NSCLC patients who had disease progression on EGFR-TKIs. NCT02374645, Date of registration: March 2nd 2015.

Efficacy of Savolitinib vs Sunitinib in Patients With MET-Driven Papillary Renal Cell Carcinoma: The SAVOIR Phase 3 Randomized Clinical Trial

Importance

Papillary renal cell carcinoma (PRCC) is the most common type of non-clear cell RCC. Because some cases of PRCC are MET-driven, MET inhibition could be a targeted treatment approach. In previous studies, savolitinib (AZD6094, HMPL-504, volitinib), a highly selective MET-tyrosine kinase inhibitor, demonstrated antitumor activity in this patient group.

Objective

To determine whether savolitinib is a better treatment option for this patient population, vs standard of care, sunitinib.

Design, Setting, and Participants

The SAVOIR phase 3, open-label, randomized clinical trial was a multicenter study carried out in 32 centers in 7 countries between July 2017 and the data cutoff in August 2019. Overall, 360 to 450 patients were to be screened to randomize approximately 180 patients. Patients were adults with MET-driven (centrally confirmed), metastatic PRCC, with 1 or more measurable lesions. Exclusion criteria included prior receipt of sunitinib or MET inhibitor treatment. Overall, 254 patients were screened.

Interventions

Patients received 600 mg of savolitinib orally once daily (qd), or 50 mg of sunitinib orally qd for 4 weeks, followed by 2 weeks without treatment.

Main Outcomes and Measures

The primary end point was progression-free survival (PFS, assessed by investigator and confirmed by blinded independent central review). Secondary end points included overall survival (OS), objective response rate (ORR), duration of response, and safety/tolerability.

Results

At data cutoff, 60 patients were randomized (savolitinib n = 33; sunitinib n = 27); most patients had chromosome 7 gain (savolitinib, 30 [91%]; sunitinib, 26 [96%]) and no prior therapy (savolitinib, 28 [85%]; sunitinib, 25 [93%]). For savolitinib and sunitinib, 4 (12%) and 10 (37%) patients were women, and the median (range) age was 60 (23-78) and 65 (31-77) years, respectively. Following availability of external data on PFS with sunitinib in patients with MET-driven disease, study enrollment was closed. Progression-free survival, OS, and ORR were numerically greater with savolitinib vs sunitinib. Median PFS was not statistically different between the 2 groups: 7.0 months (95% CI, 2.8-not calculated) for savolitinib and 5.6 months (95% CI, 4.1-6.9) for sunitinib (hazard ratio [HR], 0.71; 95% CI, 0.37-1.36; P = .31). For savolitinib and sunitinib respectively, grade 3 or higher adverse events (AEs) were reported in 14 (42%) and 22 (81%) of patients and AE-related dose modifications in 10 (30%) and 20 (74%). After discontinuation, 12 (36%) and 5 (19%) of patients on savolitinib and sunitinib respectively, received subsequent anticancer therapy.

Conclusions and Relevance

Although patient numbers and follow-up were limited, savolitinib demonstrated encouraging efficacy vs sunitinib, with fewer grade 3 or higher AEs and dose modifications. Further investigation of savolitinib as a treatment option for MET-driven PRCC is warranted.

Trial Registration

ClinicalTrials.gov Identifier: NCT03091192.

Therapeutic Drug Monitoring of Oral Anti-Hormonal Drugs in Oncology

Oral anti-hormonal drugs are essential in the treatment of breast and prostate cancer. It is well known that the interpatient variability in pharmacokinetic exposure is high for these agents and exposure-response relationships exist for many oral anti-hormonal drugs. Yet, they are still administered at fixed doses. This could lead to underdosing and thus suboptimal efficacy in some patients, while other patients could be overdosed resulting in unnecessary side effects. Therapeutic drug monitoring (TDM), individualized dosing based on measured blood concentrations of the drug, could therefore be a valid option to further optimize treatment. In this review, we provide an overview of relevant clinical pharmacokinetic and pharmacodynamic characteristics of oral anti-hormonal drugs in oncology and translate these into practical guidelines for TDM. For some agents, TDM targets are not well established yet and as a reference the median pharmacokinetic exposure could be targeted (exemestane: minimum plasma concentration (C_min) 4.1 ng/mL and enzalutamide: C_min 11.4 mg/L). However, for most drugs, exposure-efficacy analyses could be translated into specific targets (abiraterone: C_min 8.4 ng/mL, anastrozole: C_min 34.2 ng/mL, and letrozole: C_min 85.6 ng/mL). Moreover, prospective clinical trials have shown TDM to be feasible for tamoxifen, for which the exposure-efficacy threshold of its active metabolite endoxifen is 5.97 ng/mL. Based on the available data, we therefore conclude that individualized dosing based on drug concentrations is feasible and promising for oral anti-hormonal drugs and should be developed further and implemented into clinical practice.

SAVOIR: A phase III study of savolitinib versus sunitinib in pts with MET-driven papillary renal cell carcinoma (PRCC)

5002

Background: PRCC is the most common type of non-clear cell RCC, accounting for 10–15% of renal malignancies. As a subset of PRCC cases are MET-driven, MET inhibition may be an appropriate targeted treatment approach. In a single-arm Phase II study, savolitinib (AZD6094, HMPL‐504, volitinib), a highly selective MET-tyrosine kinase inhibitor, demonstrated antitumor activity in pts with MET-driven PRCC (Choueiri et al. JCO 2017). The Phase III SAVOIR study (NCT03091192) further assessed savolitinib vs standard of care sunitinib in pts with MET-driven PRCC. Methods: In this open-label (sponsor blinded), randomized study, pts with centrally confirmed MET-driven ( MET and/or HGF amplification, chromosome 7 gain and/or MET kinase domain mutations), metastatic PRCC were randomized to savolitinib 600 mg once daily (QD), or sunitinib 50 mg QD 4 weeks on / 2 weeks off. Primary objective was progression-free survival (PFS; RECIST 1.1 by blinded independent central review). Secondary objectives included overall survival (OS), objective response rate (ORR), and safety and tolerability. Results: After external data on predicted PFS with sunitinib in pts with MET-driven disease became available, study enrollment was closed. At data cutoff (Aug 2019), only 60 of the planned 180 pts were randomized (savolitinib n = 33; sunitinib n = 27). Most had chromosome 7 gain (savolitinib 91%; sunitinib 96%) and no prior therapy (savolitinib 85%; sunitinib 93%). PFS, OS, and ORR were numerically improved with savolitinib vs sunitinib (Table). CTCAE grade ≥3 adverse events (AEs) were reported in 42% and 81% of pts; dose modifications were related to AEs in 30% and 74% of pts with savolitinib and sunitinib respectively. After discontinuation, 36% of all savolitinib and 19% of all sunitinib pts received subsequent anticancer therapy. Conclusions: Although pt numbers and follow-up were limited, savolitinib demonstrated encouraging efficacy and an improved safety profile vs sunitinib, with fewer grade ≥3 AEs and fewer dose modifications required. Sunitinib performance was poorer than expected based on external retrospective data. Further investigation of savolitinib as a treatment option for MET-driven PRCC is warranted. Clinical trial information: NCT03091192 . [Table: see text]

Phase I Study of BI 853520, an Inhibitor of Focal Adhesion Kinase, in Patients with Advanced or Metastatic Nonhematologic Malignancies

BACKGROUND

Overexpression/activation of focal adhesion kinase (FAK) in human malignancies has led to its evaluation as a therapeutic target. We report the first-in-human phase I study of BI 853520, a novel, potent, highly selective FAK inhibitor.

OBJECTIVE

Our objectives were to identify the maximum tolerated dose (MTD), and to evaluate safety, pharmacokinetics (PK), pharmacodynamics (PD), biomarker expression, and preliminary activity.

PATIENTS AND METHODS

The study comprised a standard 3 + 3 dose-escalation phase followed by an expansion phase in patients with selected advanced, nonhematologic malignancies.

RESULTS

Thirty-three patients received BI 853520 in the dose-escalation phase; the MTD was 200 mg once daily (QD). Dose-limiting toxicities included proteinuria and fatigue, both of which were grade 3. Preliminary PK data supported QD dosing. In the expansion cohort, 63 patients received BI 853520 200 mg QD. Drug-related adverse events (AEs) in > 10% of patients included proteinuria (57%), nausea (57%), fatigue (51%), diarrhea (48%), vomiting (40%), decreased appetite (19%), and peripheral edema (16%). Most AEs were grade 1-2; grade 3 proteinuria, reported in 13 patients (21%), was generally reversible upon treatment interruption. Nineteen patients underwent dose reduction due to AEs, and three drug-related serious AEs were reported, none of which were fatal. Preliminary PD analysis indicated target engagement. Of 63 patients, 49 were evaluable; 17 (27%) achieved a best response of stable disease (4 with 150 + days), and 32 (51%) patients had progressive disease.

CONCLUSIONS

BI 853520 has a manageable and acceptable safety profile, favorable PK, and modest antitumor activity at an MTD of 200 mg QD in patients with selected advanced nonhematologic malignancies. CLINICALTRIALS.

GOV IDENTIFIER

NCT01335269.

Randomized, Open-Label, Crossover Studies Evaluating the Effect of Food and Liquid Formulation on the Pharmacokinetics of the Novel Focal Adhesion Kinase (FAK) Inhibitor BI 853520

Background

BI 853520 is a potent inhibitor of focal adhesion kinase and is currently under clinical development for the treatment of non-hematological malignancies.

Objective

The objective of this study was to evaluate the effect of food and liquid dispersion on the pharmacokinetics of BI 853520 in two open-label, crossover substudies.

Patients and Methods

Sixteen patients with advanced solid tumors were enrolled in each substudy. The order of administration was randomized, and pharmacokinetic samples were collected for 48 h after administration of a 200 mg dose of BI 853520. Lack of effect would be demonstrated if the 90% confidence interval (CI) of the ratio of the adjusted geometric mean (GMR) of the area under the plasma curve (area under the plasma concentration–time curve from time zero to the last quantifiable concentration at t_z [\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{AUC}}_{{0{-}t_{\text{z}} }}$$\end{document}AUC0-tz] and observed area under the plasma concentration–time curve extrapolated from time zero to infinity [AUC_0–∞,obs]) and maximum plasma concentration (C_max) did not cross the 80–125% (bioequivalence) boundaries.

Results

Adjusted GMRs (90% CIs) for the fed versus fasted state were 92.46% (74.24–115.16), 98.17% (78.53–122.74), and 87.34% (71.04–107.38) for \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{AUC}}_{{0{-}t_{\text{z}} }}$$\end{document}AUC0-tz, AUC_0–∞,obs, and C_max, respectively. Although the 90% CIs were not within bioequivalence limits for the food-effect study, the limited reductions in these pharmacokinetic parameters after administration with a high-fat meal are unlikely to be clinically relevant. Compared with a tablet, administration of BI 853520 as a liquid dispersion did not strongly affect \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{AUC}}_{{0{-}t_{\text{z}} }}$$\end{document}AUC0-tz, AUC_0–∞,obs, or C_max, resulting in adjusted GMRs (90% CIs) of 1.00 (0.92–1.09), 0.98 (0.90–1.07), and 0.93 (0.86–1.01), respectively.

Conclusions

These studies demonstrate that BI 853520 can be given with no food restrictions, and as a liquid dispersion, without strongly impacting pharmacokinetics. These pharmacokinetic properties may help make BI 853520 dosing more convenient and flexible, improving treatment compliance.

Clinical trials registration

ClinicalTrials.gov identifier: NCT01335269.

Electronic supplementary material

The online version of this article (10.1007/s11523-018-00618-0) contains supplementary material, which is available to authorized users.

Pharmacokinetic Optimization of Everolimus Dosing in Oncology: A Randomized Crossover Trial

BACKGROUND

The mammalian target of rapamycin (mTOR) inhibitor everolimus is used in the treatment of breast cancer, neuroendocrine tumors, and renal cancer. The approved 10 mg once-daily dose is associated with considerable adverse effects and it has been suggested that these are associated with the maximum concentration (C _max) of everolimus. Twice-daily dosing might be an alternative strategy with improved tolerability; however, a direct pharmacokinetic comparison of 10 mg once-daily with 5 mg twice-daily dosing is lacking.

METHODS

We performed a prospective, randomized, pharmacokinetic, crossover trial comparing everolimus 10 mg once daily with 5 mg twice daily. Patients received the first dose schedule for 2 weeks and then switched to the alternative regimen for 2 weeks. Pharmacokinetic sampling was performed on days 14 and 28.

RESULTS

Eleven patients were included in the study, of whom 10 were evaluable for pharmacokinetic analysis. On the 10 mg once-daily schedule, C _max, minimum concentration (C _min), and area under the concentration-time curve from time zero to 24 h (AUC₂₄) were 61.5 ng/mL [mean percentage coefficient of variation (CV%) 29.6], 9.6 ng/mL (CV% 35.0), and 435 ng h/mL (CV% 28.1), respectively. Switching to the 5 mg twice-daily schedule resulted in a reduction of C _max to 40.3 ng/mL (CV% 46.6) (p = 0.013), while maintaining AUC₂₄ at 436 ng h/mL (CV% 34.8) (p = 0.952). C _min increased to 13.7 ng/mL (CV% 53.9) (p = 0.018). The overall reduction in C _max was 21.2 ng/mL, or 32.7%. The C _max/C _min ratio was reduced from 6.44 (CV% 36.2) to 3.18 (CV% 35.5) (p < 0.001).

CONCLUSIONS

We demonstrated that switching from a once-daily to a twice-daily everolimus dose schedule reduces C _max without negatively impacting C _min or AUC₂₄. These results merit further investigation of the twice-daily schedule in an effort to reduce everolimus toxicity while maintaining treatment efficacy.

REGISTRATION

This trial was registered in the EurdaCT database (2014-004833-25) and the Netherlands Trial Registry (NTR4908).

Abstract 4897: Detection of MET-mediated EGFR tyrosine kinase inhibitor (TKI) resistance in advanced non-small cell lung cancer (NSCLC): biomarker analysis of the TATTON study

EGFR-TKIs like osimertinib are widely used to treat advanced EGFR-mutant NSCLC, however tumors inevitably acquire resistance. Amplification of MET occurs in ~20% of EGFR-TKI resistant tumors. Previous studies have used a variety of technologies (FISH, IHC, NGS, ctDNA) with mixed success in identifying MET-driven tumors. Thus, there is an urgent need to better understand the reliability of these assays for the detection of MET-driven EGFR-TKI resistance in NSCLC.

In the TATTON study (NCT02143466), the combination of osimertinib and savolitinib (AZD6094, HMPL-504, volitinib), a potent and selective MET-TKI, has demonstrated encouraging anti-tumor activity in patients with NSCLC and MET-driven EGFR-TKI resistance. During screening, MET testing (central, or local with central confirmation) was performed on tumor tissue collected after the most recent therapy. Informative central MET FISH screening/confirmation results were generated for 254 consented patients. MET overexpression and amplification were further assayed centrally using tissue IHC (n=81), tissue NGS (n=117; Foundation Medicine), and ctDNA NGS (n=199; Guardant Health). Standard NGS provider MET amplification calls were used. Central IHC positivity was defined as 3+ in ≥50% of tumor cells. Central FISH+ was defined as either amplification (MET:CEP7 ratio ≥2) or polysomy (gene copy number ≥5 if MET:CEP7 &lt;2). MET FISH was used as the common comparator across assays.

Central MET FISH+ was found in 123/254 tumors (48%; 75 with amplification, 48 with polysomy), an elevated prevalence likely related to local MET+ prescreening. Comparison of tissue NGS with FISH (n=95) identified high negative-percent agreement (NPA, 98%) but modest positive-percent agreement (PPA, 48%). Further investigation indicated NGS PPA is highly dependent on the FISH result, with higher PPA for amplification (88%) but low PPA for polysomy (4%). Similarly, comparison of ctDNA NGS with FISH (n=112) yielded modest NPA (90%) and PPA of only 25% (43% for amplification; 10% for polysomy). PPA improved to 50% (64% for amplification; 30% for polysomy) when limited to 46 patients with an EGFR mutation detected at &gt;5% allelic fraction in ctDNA. Comparison of IHC with FISH (n=52) identified a 63% NPA and 72% PPA. Notably, of 28 IHC 3+ tumors, 10 (36%) were negative by FISH.

Tissue NGS identifies a subset of MET FISH+ tumors, however MET polysomy is largely missed by NGS assays. MET IHC 3+ staining overlaps extensively with MET FISH+ but also identifies additional potentially MET-dependent tumors. When combined with future clinical efficacy data, this technical comparison will help inform a prospective biomarker strategy for the detection of MET-driven EGFR-TKI resistance in NSCLC.

Citation Format: Ryan J. Hartmaier, Ji-Youn Han, Byoung Chul Cho, Melanie M. Frigault, Aleksandra Markovets, Anne L’Hernault, David Duncan, Pierre Lao-Sirieix, J. Carl Barrett, Remy B. Verheijen, Dana Ghiorghiu, Jonathan Wessen, Geoffrey R. Oxnard. Detection of MET-mediated EGFR tyrosine kinase inhibitor (TKI) resistance in advanced non-small cell lung cancer (NSCLC): biomarker analysis of the TATTON study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4897.

Boosting pazopanib exposure by splitting intake moments: A prospective pharmacokinetic study in cancer patients

3119

Background: Pazopanib is approved for the treatment of renal cell carcinoma (RCC) and soft tissue sarcoma (STS). Due to high (40-70%) interpatient variability in pharmacokinetic (PK) exposure, 16-20% of patients do not reach the 20 mg/L exposure threshold related to prolonged progression free survival (20 weeks versus 52 weeks, respectively) with the currently used fixed dose of 800 mg QD (Suttle, 2014; Verheijen, 2017). PK simulations showed that, due to non-linear absorption of pazopanib, splitting the intake (400 mg BID) leads to an increase in Cmin and AUC0-24h of 75% and 59%, respectively (Yu, 2017). This study aimed to show whether switching patients from an 800 mg QD to a 400 mg BID dose schedule will lead to a significant increase in PK exposure. Methods: We performed a prospective PK trial (NL6137) in which PK sampling at the 800 mg QD dose schedule occurred at day 1, after which the intake moments were split into 400 mg BID during one week, followed by PK sampling at day 8. Paired samples t-tests were used to assess differences in Cmin, Cmax and AUC0-24h between these two dose schedules. To detect an increase in PK exposure of 50% (2-sided α = 0.05 and β = 0.20), 10 evaluable patients were needed. Results: Eleven patients (6 RCC and 5 STS) have been included, of whom ten were evaluable for PK analyses. Using the 800 mg QD dose schedule mean Cmin, Cmax and AUC0-24h were 26.7 mg/L (coefficient of variation (CV%) 44.7), 46.1 mg/L (CV% 37.1) and 809 mg h/L (CV% 42.1), respectively. Switching to 400 mg BID resulted in an increase of both Cmin and AUC0-24h to 40.7 mg/L (CV% 37.0, p = 0.013) and 1059 mg h/L (CV% 33.1, p = 0.068), respectively, while Cmax did not significantly change (56.5 mg/L, CV% 33.2, p = 0.185). One patient (9%) experienced grade 3 diarrhea after splitting intake moments, leading to treatment interruption. This strategy could potentially save up to 2000 USD/patient/month compared to conventional dose increments. Conclusions: This study demonstrates that boosting pazopanib exposure by splitting intake moments leads to a significant increase in Cmin, of 52%, with acceptable tolerability. Therefore, this new dose schedule offers a safe and cost-neutral opportunity to optimize treatment for patients with low PK exposure. Clinical trial information: NL6137.

Validation and clinical application of an LC-MS/MS method for the quantification of everolimus using volumetric absorptive microsampling

Everolimus is a mammalian target of rapamycin inhibitor approved for the treatment of various tumor types. Less invasive measurement of everolimus concentrations could facilitate pharmacokinetic studies and personalized dosing based on whole blood concentrations, known as therapeutic drug monitoring. Volumetric Absorptive Microsampling (VAMS) has been introduced as a patient friendly, less invasive sampling technique to obtain an accurate volume of whole blood regardless of hematocrit value. We describe the bioanalytical validation and clinical application of a liquid chromatography tandem mass spectrometry (LC-MS/MS) method to quantify everolimus using VAMS. For the quantification, ¹³C₂D₄-Everolimus was used as internal standard (IS). Everolimus and the IS were extracted with methanol from the VAMS device, which was evaporated after ultrasonification and shaking. The residue was reconstituted in 20 mM ammonium formate buffer and methanol (50%, v/v) of which 5 μL was injected into the LC-MS/MS system. Quantification was performed for the ammonium adduct of everolimus in positive electrospray ion mode. The VAMS method met all pre-defined validation criteria. Accuracy and precision were within 11.1% and ≤14.6%, respectively. Samples were shown to be stable on the VAMS device for at least 362 days at ambient temperatures. Considerable biases from -20 to 31% were observed over a 30-50% hematocrit range. Although the method fulfilled all validation criteria, the perceived advantage of VAMS over dried blood spot sampling could not be demonstrated. Despite the effect of hematocrit, using an empirically derived formula the whole blood everolimus concentration could be back calculated with reasonable accuracy in the clinical application study.

Molecular Imaging of ABCB1 and ABCG2 Inhibition at the Human Blood-Brain Barrier Using Elacridar and 11C-Erlotinib PET

Transporters such as ABCB1 and ABCG2 limit the exposure of several anticancer drugs to the brain, leading to suboptimal treatment in the central nervous system. The purpose of this study was to investigate the effects of the ABCB1 and ABCG2 inhibitor elacridar on brain uptake using ¹¹C-erlotinib PET. Methods: Elacridar and cold erlotinib were administered orally to wild-type (WT) and Abcb1a/b;Abcg2 knockout mice. In addition, brain uptake was measured using ¹¹C-erlotinib imaging and ex vivo scintillation counting in knockout and WT mice. Six patients with advanced solid tumors underwent ¹¹C-erlotinib PET scans before and after a 1,000-mg dose of elacridar. ¹¹C-erlotinib brain uptake was quantified by pharmacokinetic modeling using volume of distribution (V_T) as the outcome parameter. In addition, ¹⁵O-H₂O scans to measure cerebral blood flow were acquired before each ¹¹C-erlotinib scan. Results: Brain uptake of ¹¹C-erlotinib was 2.6-fold higher in Abcb1a/b;Abcg2 knockout mice than in WT mice, measured as percentage injected dose per gram of tissue (P = 0.01). In WT mice, the addition of elacridar (at systemic plasma concentrations of ≥200 ng/mL) resulted in an increased brain concentration of erlotinib, without affecting erlotinib plasma concentration. In patients, the V_T of ¹¹C-erlotinib did not increase after intake of elacridar (0.213 ± 0.12 vs. 0.205 ± 0.07, P = 0.91). ¹⁵O-H₂O PET showed no significant changes in cerebral blood flow. Elacridar exposure in patients was 401 ± 154 ng/mL. No increase in V_T with increased elacridar plasma exposure was found over the 271-619 ng/mL range. Conclusion: When Abcb1 and Abcg2 were disrupted in mice, brain uptake of ¹¹C-erlotinib increased both at a tracer dose and at a pharmacologic dose. In patients, brain uptake of ¹¹C-erlotinib was not higher after administration of elacridar. The more pronounced role that ABCG2 appears to play at the human blood-brain barrier and the lower potency of elacridar to inhibit ABCG2 may be an explanation of these interspecies differences.

Imatinib Pharmacokinetics in a Large Observational Cohort of Gastrointestinal Stromal Tumour Patients

BACKGROUND

Low trough imatinib concentration (C _min) values have been associated with poor clinical outcomes in gastrointestinal stromal tumour (GIST) patients. This study describes the pharmacokinetics of imatinib in a large cohort of GIST patients in routine clinical care.

METHODS

An observational study was performed in imatinib-treated GIST patients. Patient and tumour characteristics were derived from the Dutch GIST Registry and medical records. Imatinib concentrations were measured by liquid chromatography with tandem mass spectrometry. The analyses included the occurrence of a low imatinib C _min (<1000 µg/L), the change in the C _min over time and the correlation between exposure and response.

RESULTS

In total, 421 plasma samples were available from 108 GIST patients. Most patients (79.6 %) received an imatinib dose of 400 mg. The inter- and intrapatient variabilities in C _min were 54 and 23 %, respectively. In the first steady-state sample, 44.4 % of patients presented with C _min values <1000 µg/L; 32.4 % of patients had values <1000 µg/L in >75 % of their samples. Only 33.3 % of patients had C _min values ≥1000 µg/L in all measured samples. No decrease in C _min over time was found (P > 0.05). Fifty-seven (91.9 %) of 62 palliative-treated patients had a tumour response (median C _min 1271 µg/L). Five palliative patients (8.1 %) did not respond (median C _min 920 µg/L). Given the limited number of non-responders in this cohort, no statistically significant association with clinical benefit could be demonstrated.

CONCLUSION

In routine clinical care, one third of GIST patients are systematically underexposed with a fixed dose of imatinib. Prospective clinical studies are needed to investigate the value of C _min-guided imatinib dosing in GIST patients.

Clinical pharmacokinetics of an amorphous solid dispersion tablet of elacridar

Elacridar is an inhibitor of the permeability glycoprotein (P-gp) and the breast cancer resistance protein (BCRP) and is a promising absorption enhancer of drugs that are substrates of these drug-efflux transporters. However, elacridar is practically insoluble in water, resulting in low bioavailability which currently limits its clinical application. We evaluated the in vitro dissolution and clinical pharmacokinetics of a novel amorphous solid dispersion (ASD) tablet containing elacridar. The dissolution from ASD tablets was compared to that from a crystalline powder mixture in a USP type II dissolution apparatus. The pharmacokinetics of the ASD tablet were evaluated in an exploratory clinical study at oral doses of 25, 250, or 1000 mg in 12 healthy volunteers. A target C_max was set at ≥ 200 ng/mL based on previous clinical data. The in vitro dissolution from the ASD tablet was 16.9 ± 3.7 times higher compared to that from a crystalline powder mixture. C_max and AUC_0-∞ increased linearly with dose over the explored range. The target C_max of ≥ 200 ng/mL was achieved at the 1000-mg dose level. At this dose, the C_max and AUC_0-∞ were 326 ± 67 ng/mL and 13.4 ± 8.6 · 10³ ng · h/mL, respectively. In summary, the ASD tablet was well tolerated, resulted in relevant pharmacokinetic exposure, and can be used for proof-of-concept clinical studies.

Exposure-survival analyses of pazopanib in renal cell carcinoma and soft tissue sarcoma patients: opportunities for dose optimization

Background

Pazopanib is an angiogenesis inhibitor approved for the treatment of renal cell carcinoma and soft tissue sarcoma. Post hoc analysis of a clinical trial demonstrated a relationship between pazopanib trough concentrations (C_min) and treatment efficacy. The aim of this study was to explore the pharmacokinetics and exposure-survival relationships of pazopanib in a real-world patient cohort.

Patients and methods

Renal cell cancer and soft tissue sarcoma patients who had at least one pazopanib plasma concentration available were included. Using calculated C_min values and a threshold of > 20 mg/L, univariate and multivariate exposure-survival analyses were performed.

Results

Sixty-one patients were included, of which 16.4% were underexposed (mean C_min < 20 mg/L) using the 800 mg fixed-dosed schedule. In univariate analysis C_min > 20 mg/L was related to longer progression free survival in renal cell cancer patients (34.1 vs. 12.5 weeks, n = 35, p = 0.027) and the overall population (25.0 vs. 8.8 weeks, n = 61, p = 0.012), but not in the sarcoma subgroup (18.7 vs. 8.8 weeks, n = 26, p = 0.142). In multivariate analysis C_min > 20 mg/L was associated with hazard ratios of 0.25 (p = 0.021) in renal cancer, 0.12 (p = 0.011) in sarcoma and 0.38 (p = 0.017) in a pooled analysis.

Conclusion

This study confirms that pazopanib C_min > 20 mg/L relates to better progression free survival in renal cancer and points towards a similar trend in sarcoma patients. C_min monitoring of pazopanib can help identify patients with low C_min for whom individualized treatment at a higher dose may be appropriate.

Practical Recommendations for Therapeutic Drug Monitoring of Kinase Inhibitors in Oncology

Despite the fact that pharmacokinetic exposure of kinase inhibitors (KIs) is highly variable and clear relationships exist between exposure and treatment outcomes, fixed dosing is still standard practice. This review aims to summarize the available clinical pharmacokinetic and pharmacodynamic data into practical guidelines for individualized dosing of KIs through therapeutic drug monitoring (TDM). Additionally, we provide an overview of prospective TDM trials and discuss the future steps needed for further implementation of TDM of KIs.

Monitoring of circulating tumor DNA in non-small cell lung cancer patients treated with EGFR-inhibitors

11535

Background: Epidermal growth factor receptor (EGFR) inhibitors such as erlotinib and gefitinib are routinely used in the treatment of non-small cell lung cancer (NSCLC). Monitoring of EGFR mutations in circulating tumor DNA (ctDNA) derived from plasma has been proposed as an alternative for repeated tumor biopsies. Our aim was to investigate the dynamics of ctDNA in a cohort of NSCLC patients and explore the roles of EGFR driver and resistance mutations in predicting disease progression and progression free survival (PFS). Methods: NSCLC patients treated with either erlotinib or gefitinib as first-line anti-EGFR therapy were included. Clinical data was collected retrospectively from medical records. Plasma samples collected as part of routine care were analyzed. First DNA was isolated from plasma using the QIAsymphony SP (Qiagen). Then EGFR driver (L858R and exon 19 deletions) and resistance (T790M) mutations were quantified using the X100 Droplet Digital PCR and analyzed using QuantaSoft software (Bio-Rad). The dynamics of ctDNA mutations over time and the relationship between copy numbers and progression free survival were explored. Results: 68 NSCLC patients and 249 plasma samples (1-13 per patient) were included in the analysis. In 33 patients, the T790M mutation was detected. The median (range) T790M concentration in these samples was of 7.3 (5.1 - 3688.7) copies/mL. In 30 patients, the L858R or exon 19 deletion driver mutations were found in median concentrations of 11.7 (5.1 – 12393.3) and 27.9 (5.9 – 2896.7) copies/mL, respectively. Using local polynomial regression, the copies/mL of EGFR driver mutations increased several weeks prior to progression on standard response evaluation. In Kaplan-Meier analysis, patients with a detectable T790M mutation during the first 8 weeks of treatment had a shorter PFS (7.6 versus 14.4 months, p < 0.01, log-rank test). Conclusions: Early detection of the T790M mutation in plasma ctDNA is related to poor PFS. Furthermore, an increase in the copies/mL of the EGFR driver mutation over time may predict clinical progression.

Individualized Pazopanib Dosing: A Prospective Feasibility Study in Cancer Patients

PURPOSE

Pazopanib is a tyrosine kinase inhibitor approved for the treatment of renal cell carcinoma and soft tissue sarcoma. Retrospective analyses have shown that an increased median progression-free survival and tumor shrinkage appear in patients with higher plasma trough levels (C_min). Therefore, patients with low C_min might benefit from pharmacokinetically guided individualized dosing.

EXPERIMENTAL DESIGN

We conducted a prospective multicenter trial in 30 patients with advanced solid tumors. Pazopanib C_min was measured weekly by LC-MS/MS. At weeks 3, 5, and 7, the pazopanib dose was increased if the measured C_min was <20 mg/L and toxicity was <grade 3.

RESULTS

In total, 17 patients had at least one C_min <20 mg/L at weeks 3, 5, and 7. Of these, 10 were successfully treated with a pharmacokinetically guided dose escalation, leading to daily dosages ranging from 1,000 to 1,800 mg. C_min in these patients increased significantly from 13.2 (38.0%) mg/L [mean (CV%)] to 22.9 mg/L (44.9%). Thirteen patients had all C_min levels ≥20.0 mg/L. Of these, 9 patients with a high C_min of 51.3 mg/L (45.1%) experienced ≥grade 3 toxicity and subsequently required a dose reduction to 600 or 400 mg daily, yet in these patients, C_min remained above the threshold at 28.2 mg/L (25.3%).

CONCLUSIONS

A pharmacokinetically guided individualized dosing algorithm was successfully applied and evaluated. The dosing algorithm led to patients being treated at dosages ranging from 400 to 1,800 mg daily. Further studies are needed to show a benefit of individualized dosing on clinical outcomes, such as progression-free survival. Clin Cancer Res; 22(23); 5738-46. ©2016 AACRSee related commentary by Ornstein and Rini, p. 5626.

Abstract 2664: Next generation PET imaging agents: The development of radiolabeled c-Met specific Anticalin 89Zr-PRS-110 with diagnostic and therapeutic drug monitoring applications

The oncogene c-Met is a clinically validated target having been shown to be involved in tumorigenesis. Imaging agents capable of quantifying c-Met expression in human tumors would be a valuable tool for aiding diagnosis, drug scheduling and monitoring the response to targeted therapies. Anticalins are a novel class of biopharmaceuticals based on the human lipocalin scaffold with many properties which make them desirable imaging agents including their smaller size and ease of manufacturing when compared to antibodies. PRS-110 is a c-Met specific anticalin which is being developed as a therapeutic and imaging modality. The aim of this study was to evaluate the utility of the c-Met anticalin as a positron emission tomography (PET) imaging agent and analyze its biodistribution in human tumor bearing mice.

Methods: A zirconium-89 (89Zr) labeled version of PRS-110 was generated and biodistribution studies were performed 96 h after single dose injection of the tracer (10 to 500 μg) into Balb/c mice bearing subcutaneous c-Met expressing human H441 non-small cell lung cancer tumors. PET imaging was executed at 6, 24, 48 and 96 h after injection of 50 μg 89Zr-PRS-110 to mice bearing H441 (c-Met ++), primary glioblastoma U87-MG (c-Met +) or ovarian cancer A2780 (c-Met -) xenografts. After the final scan, biodistribution analysis was performed. The excised tumors were analyzed for c-Met expression by immunohistochemistry and fluorescent PRS-110-800CW distribution by fluorescence microscopy.

Results: Biodistribution analyses showed a PRS-110 dose-dependent 89Zr-PRS-110 H441-tumor uptake, with the highest tumor uptake at 10 μg PRS-110 resulting in 7.5 %ID/g at 96 h after tracer injection. MicroPET imaging revealed specific tumor uptake of 89Zr-PRS-110 in the c-Met expressing H441 and U87 tumors while imaging of the c-Met negative A2780 tumor model showed background level similar to a non-specific anticalin control. Biodistribution data supported the microPET findings, showing ex vivo tumor uptake of 89Zr-PRS-110 of 5.9, 1.8 and 1.7 %ID/g in H441, U87 and A2780 xenografts respectively, which correlated with c-Met expression levels. Tumor : blood ratios of 89Zr-PRS-110 compared to 89Zr-Tlc-PEG confirmed these finding. Ex vivo fluorescence revealed intracellular presence of PRS-110 96 h after tracer injection.

Conclusion: 89Zr-PRS-110 specifically accumulates in c-Met expressing tumors. PET imaging with this tracer provides real-time non-invasive information about PRS-110 distribution and tumor accumulation. This makes 89Zr-PRS-110, which is ready for clinical evaluation, of interest for the clinical development of PRS-110.

Citation Format: Anton G.T. Terwisscha van Scheltinga, Elisabeth G.E. de Vries, Marlon Hinner, Remy B. Verheijen, Andrea Allesdorfer, Laurent Audoly, Wouter B. Nagengast, Carolien P. Schröder, Martin Hülsmeyer, Jos G.W. Kosterink, Marjolijn N. Lub-de Hooge, Shane A. Olwill. Next generation PET imaging agents: The development of radiolabeled c-Met specific Anticalin 89Zr-PRS-110 with diagnostic and therapeutic drug monitoring applications. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2664. doi:10.1158/1538-7445.AM2013-2664