A global phase II randomized trial comparing oral taxane ModraDoc006/r to intravenous docetaxel in metastatic castration resistant prostate cancer

STUDY AIM

ModraDoc006, an oral formulation of docetaxel, is co-administered with the cytochrome P450-3A4 and P-glycoprotein inhibitor, ritonavir (r): ModraDoc006/r. The preliminary efficacy and safety of oral ModraDoc006/r was evaluated in a global randomized phase II trial and compared to the current standard chemotherapy regimen of intravenous (i.v.) docetaxel and prednisone.

METHODS

103 mCRPC patients, chemotherapy-naïve with/without abiraterone and/or enzalutamide pretreated, with adequate organ function and evaluable disease per RECIST v1.1 and PCWG3 guidelines were randomized 1:1 into two cohorts. In Cohort 1, 49 patients received docetaxel 75 mg/m2 i.v. every 3 weeks (Q3W). In Cohort 2, 52 patients received ModraDoc006/r; 21 patients with a starting dose of ModraDoc006 30 mg with ritonavir 200 mg in the morning and ModraDoc006 20 mg with ritonavir 100 mg in the evening (30-20/200-100 mg) bi-daily-once-weekly (BIDW) on Days 1, 8, and 15 of a 21-day cycle. To alleviate tolerability, the starting dose was amended to ModraDoc006/r 20-20/200-100 mg in another 31 patients. All patients received prednisone 10 mg daily. Primary endpoint was rPFS.

RESULTS

There was no significant difference in rPFS between the 2 arms (p = 0.1465). Median rPFS was 9.5 months and 11.1 months (95% CI) for ModraDoc006/r and i.v. docetaxel, respectively. Partial response was noted in 44.1% and 38.7% measurable disease patients, and 50% decline of PSA was seen in 23 (50%) and 26 (56.5%) evaluable cases treated with ModraDoc006/r and i.v. docetaxel, respectively. The safety profile of ModraDoc006/r 20-20/200-100 mg dose was significantly better than i.v. docetaxel, with mild (mostly Grade 1) gastrointestinal toxicities, no hematologic adverse events, and neuropathy and alopecia incidence of 11.5% and 25%, respectively.

CONCLUSIONS

ModraDoc006/r potentially represents a widely applicable, convenient, effective, and better tolerated oral taxane therapy option for mCRPC. Further investigation of ModraDoc006/r in a large randomized trial is warranted.

A phase 2 randomized study of oral docetaxel plus ritonavir (ModraDoc006/r) in patients with metastatic castration-resistant prostate cancer (mCRPC)

5016

Background: Intravenous (IV) docetaxel and oral prednisone is a standard of care regimen in patients (pts) with mCRPC. ModraDoc006 is an oral formulation of docetaxel. To enhance bioavailability of ModraDoc006, it is co-administered with ritonavir (/r). The ModraDoc006 and ritonavir combination is active in multiple docetaxel and cabazitaxel-resistant prostate cancer cell-lines The oral combination (ModraDoc006/r) was compared to IV docetaxel in a randomized phase 2b study in pts with mCRPC evaluating two doses of ModraDoc006/r (30-20/200-100 mg and 20-20/200-100 mg). Data on outcomes in the larger cohort, receiving the lower dose, are being presented. Methods: Eligible pts had mCRPC, performance status of 0-1 and no prior chemotherapy for mCRPC. Sixty-two pts were enrolled in open label 1:1 randomized study comparing ModraDoc006/r 20-20 mg combined with 200-100 mg ritonavir in a bi-daily weekly schedule (“20-20/200-100 mg”), with IV docetaxel 75 mg/m2 in 21-day cycles. All pts received 5 mg oral prednisone twice daily. Primary endpoint was radiographic progression free survival (rPFS) per PCWG-3 criteria. Secondary objectives included ORR, PSA-PFS, time to skeletal related events, disease control rate, duration of response, and safety assessments. Results: 31 pts were enrolled on IV docetaxel 75 mg/m2 and 31 on ModraDoc006/r 20-20/200-100 mg. Of these, 57 were included in the analysis for rPFS, and 32 pts with measurable disease were included in the ORR analysis. Median PSA was 46 (range 1 to 1460 ng/ml). Prior therapy with enzalutamide in 8 pts, abiraterone in 10 pts. ModraDoc006/r was better tolerated with 0% all grades neutropenia and anemia, as compared to 26% (19% ≥G3) and 16% respectively on IV docetaxel. Neuropathy was significantly reduced at 9.7% G1 only on ModraDoc006/r vs 9.7% G1 and 19.4% G2 on IV docetaxel, whereas alopecia was reduced to 16.1% G1 and 6.5% G2 on ModraDoc006/r vs. 22.6% G1 and 19.4% G2 on IV docetaxel. GI toxicities were broadly comparable with diarrhea 32% (3% ≥G3) vs 29%, nausea 29% vs 13% and stomatitis 3% (G3) vs 13% (3% ≥G3), respectively. Conclusions: ModraDoc006/r demonstrated a favorable safety profile and comparable efficacy to IV docetaxel in pts with mCRPC, thus providing a compelling rationale for conduct of an expanded pivotal program. A key clinical program focus is the comparison of ModraDoc006/r to best available therapy in refractory mCRPC. Studies of ModraDoc006/r in other malignancies are also in active development. Clinical trial information: NCT04028388. [Table: see text]

Phase 2 randomized trial of ModraDoc006/r, oral docetaxel plus ritonavir, versus intravenous docetaxel in metastatic castration resistant prostate cancer (mCRPC)

117

Background: Intravenous (IV) docetaxel and oral prednisone is a standard of care regimen in mCRPC. ModraDoc006 is a novel, oral tablet formulation of docetaxel. To enhance bioavailability, it is co-administered with ritonavir (/r), an inhibitor of cytochrome p450 3A4 and P-glycoprotein metabolic enzymes. The oral combination, denoted as ModraDoc006/r, may be superior to IV docetaxel in terms of safety profile, avoiding infusions, patient quality of life (QoL) and overall resource utilization. Safety of ModraDoc006/r in mCRPC was established in a previous phase Ib trial. Methods: We conducted an open label 1:1 randomized study of ModraDoc006/r bi-daily weekly dosing (BIDW) regimen versus IV docetaxel 75 mg/m2 in 21-day cycles. Initially, BIDW 30-20 mg ModraDoc006 combined with 200-100 mg ritonavir was administered on days 1, 8 and 15 of a 21-day cycle. After 39 patients the starting dose was reduced to 20-20 mg BIDW with ritonavir 200 mg in the morning and 100 mg with the evening dose to improve tolerability. All patients received 5 mg oral prednisone twice daily. Primary endpoint was radiographic progression free survival (rPFS) per PCWG-3 criteria. Secondary objectives were ORR, PSA-PFS, time to skeletal related events, disease control rate, duration of response, and safety assessments. Patient reported outcomes and health-related QoL was assessed with treatment satisfaction and FACT-P questionnaires at baseline and after cycles 3, 6 and 10. Results: Enrollment is complete with 101 patients accrued; 49 on IV docetaxel, 52 on ModraDoc006/r (21 on 30-20 mg and 31 on ModraDoc006/r 20-20 mg). 69 patients had measurable disease and median PSA was 67ng/ml (range 0,2 to 1697 ng/ml). IV docetaxel vs ModraDoc006/r 30-20 mg and 20-20 mg demonstrated ORR of 39% vs 50% and 33%, and PSA responses of 57% vs 53% and 48%. All grades neutropenia and neuropathy was noted in 0% and 6% with ModraDoc006/r 20-20 mg therapy and was better than the incidence of 14% (5% ≥G3) and 14% with ModraDoc006/r 30-20 mg, and 27% (20% ≥G3) and 31% respectively on IV docetaxel. Alopecia was also reduced at 23% on ModraDoc006/r 20-20 mg and 29% on ModraDoc006/r 30-20 mg vs 43% on IV docetaxel. GI toxicities were slightly more frequent, but predominantly mild, in the ModraDoc006/r arm: at 20-20 mg dose, all grades diarrhea 32% (3% ≥G3), nausea 29% and stomatitis 3% (G3); at 30-20 mg dose 62% diarrhea (19% ≥G3), 38% nausea and 14% stomatitis (5% ≥G3); and in IV docetaxel, 24% diarrhea, 16% nausea and 10% stomatitis (4% ≥G3). Conclusions: Hematological toxicities and adverse events neuropathy and alopecia were lower with ModraDoc006/r than with IV docetaxel. ModraDoc006/r represents a convenient, oral, tolerable option for patients with mCRPC. ModraDoc006/r has comparable efficacy and a favorable tolerability profile as compared to IV docetaxel and merits further development in patients with mCRPC. Clinical trial information: NCT04028388.

ModraDoc006, an oral docetaxel formulation in combination with ritonavir (ModraDoc006/r), in metastatic castration-resistant prostate cancer patients: A phase Ib study

BACKGROUND

ModraDoc006 is an oral formulation of docetaxel, which is co-administered with the cytochrome P450 3A4 and P-glycoprotein inhibitor ritonavir (r): ModraDoc006/r. Weekly treatment with ModraDoc006/r had been evaluated in phase I trials in patients with different types of advanced solid tumors, but up to this point in time not in patients with metastatic castration-resistant prostate cancer (mCRPC).

AIM

We assessed safety and pharmacokinetics (PK) of ModraDoc006/r to establish the recommended phase 2 dose (RP2D) in patients with mCRPC.

METHODS

mCRPC patients, treatment naïve or following abiraterone or enzalutamide treatment, were included. Dose-escalation of ModraDoc006/r was based on safety and docetaxel PK. Antitumor activity was assessed by serum prostate-specific antigen (PSA) and radiological evaluation.

RESULTS

Cohort 1 (n = 5) received once weekly ModraDoc006 30 mg with ritonavir 100 mg in the morning, and ModraDoc006 20 mg with ritonavir 100 mg in the evening (30-20/100-100). The mean docetaxel area under the plasma concentration-time curve (mAUC0-inf) was 461 ng/mL × h with 1 dose limiting toxicity (DLT); grade 3 alanine transferase increase. In cohort 2 (n = 6, ModraDoc006/r 30-20/200-200), the mAUC0-inf was 1687 ng/mL × h with 2 DLTs; grade 3 diarrhea and mucositis. In cohort 3A (n = 6, ModraDoc006/r 30-20/200-100), the mAUC0-inf was 1517 ng/mL × h with 1 DLT; grade 3 diarrhea. In cohort 3B (n = 3, ModraDoc006/r 20-20/200-100), the mAUC0-inf was 558 ng/mL × h without DLTs. The mAUC0-inf exceeded estimated exposures of intravenous docetaxel in cohort 2 and 3A, was lower in cohort 1 and was in range in cohort 3B. PSA decreases of >50% occurred in 6/10 evaluable patients throughout the various cohorts. In five radiological evaluable patients, two confirmed partial responses were observed.

CONCLUSION

The RP2D was established at weekly ModraDoc006/r 30-20/200-100. Observed PSA and radiological responses suggest promising clinical activity. These results have led to an ongoing randomized Phase 2b study, comparing weekly ModraDoc006/r with 3-weekly IV docetaxel in patients with mCRPC.

Phase IIb trial of oral ModraDoc006/r as a tolerable and effective option in comparison with intravenous docetaxel in metastatic castration-resistant prostate cancer (mCRPC)

132

Background: ModraDoc006 is a novel, oral tablet formulation of docetaxel. To enhance bioavailability, it is co-administered with ritonavir (r), an inhibitor of cytochrome P450 3A4 and P-glycoprotein. The oral combination, denoted ModraDoc006/r, has potential advantages in terms of patient convenience, elimination of infusion-related reactions and avoiding prophylactic steroid administration, as well as safety benefits. Safety and preliminary efficacy of ModraDoc006/r in mCRPC were established in a prior phase Ib trial. Methods: This is an open label 1:1 randomized phase IIb trial of ModraDoc006/r bi-daily once weekly (BIDW) regimen versus IV docetaxel 75 mg/m2 q day 21. Initially, BIDW 30-20 mg ModraDoc006 combined with 200-100 mg ritonavir was administered on days 1, 8 and 15 of a 21-day cycle. After 39 patients, the dose of ModraDoc006 was reduced to 20-20 mg BIDW to improve GI tolerability. All patients received 5 mg oral prednisone BID. Imaging is obtained every 8-9 weeks for the first 24 weeks, every 12 weeks thereafter. Initially mCRPC patients with RECIST 1.1 measurable disease were eligible; this was amended to evaluable disease per Prostate Cancer Working Group 3 (PCWG3) to allow for wider recruitment. No prior taxane therapy is allowed. The primary efficacy endpoint is radiographic progression free survival (rPFS) per PCWG3 criteria. Secondary objectives include objective response rate, PSA-PFS, time to skeletal related events, disease control rate, duration of response and safety. Patient reported outcomes, QoL and FACT-P questionnaires are assessed. It is expected that ModraDoc006/r will be as effective as IV docetaxel. A sample size of approximately 50 evaluable patients per arm will provide a point estimate of the primary endpoint of rPFS for this study. Results: At the data cut-off of 30 Nov 2020, 90 patients were enrolled in US and EU: 44 patients had been randomized to IV docetaxel and 46 to ModraDoc006/r, with 58 patients currently on treatment. Preliminary PSA response rates and rPFS were noted to be comparable in both treatment arms. ModraDoc006/r was mainly associated with mild and reversible GI-toxicity, of which grade and incidence were reduced at 20-20 mg compared to the initial dose-level of 30-20 mg ModraDoc006. Myelosuppression and neurotoxicity were low to negligible in the ModraDoc006/r arm, with low accompanying levels of alopecia. Conclusions: Adverse events of cytopenias and alopecia were lower with ModraDoc006/r, and preliminary efficacy appears comparable in both arms. Oral chemotherapy option has become critically important during the COVID-19 pandemic. Preliminary data reveals that ModraDoc006/r is an attractive oral option in mCRPC with favorable toxicity profile and comparable efficacy. Clinical trial information: NCT04028388.

ModraDoc006, an oral docetaxel formulation in combination with ritonavir (ModraDoc006/r), in metastasized castration-resistant prostate cancer (mCRPC): A multicenter phase I study

79

Background: ModraDoc006 is a novel formulation of docetaxel and to enhance bioavailability, this tablet is co-administered with ritonavir (r), an inhibitor of cytochrome p450 3A4 and P-glycoprotein. The safety, anti-tumor activity and pharmacokinetics (PK) of ModraDoc006/r were investigated by dose-escalation in patients with mCRPC, to propose a recommended phase 2 dose (RP2D). Methods: Progressive mCRPC patients, who were treatment naïve or previously treated with either abiraterone or enzalutamide, received a maximum of 30 weekly cycles of ModraDoc006/r in a bi-daily once weekly (BIDW) schedule. Plasma docetaxel concentrations were determined at the first 2 cycles up to 48h after intake of ModraDoc006/r. Adverse events were evaluated using the Common Terminology Criteria for Adverse Events (CTCAE) version 4.03. Serum Prostate Specific Antigen (PSA) levels were assessed every 6 weeks. Results: 23 patients were included, of whom 20 were evaluable for safety and PK. In 5 patients, the initial 30-20/100-100 dose was explored, with observation of one dose limiting toxicity (DLT) (grade 3 alanine aminotransferase increase). The next dose level of 30-20/200-200 resulted in 2 DLTs in 6 patients (grade 3 diarrhea and mucositis). Subsequently, two intermediate dose levels: 30-20/200-100 and 20-20/200-100 were explored in 6 and 3 patients. At the 30-20/200-100 dose, an adequate docetaxel exposure was achieved and 1 DLT (grade 3 diarrhea) was observed, with no DLTs at the 20-20/200-100 dose. Common treatment-related AEs (occurring in > 30% of all patients) were diarrhea, nausea, vomiting, anorexia and fatigue. Five patients completed the maximum of 30 weekly treatments. In 10 patients, evaluable for anti-tumor activity after treatment with ≥9 cycles, 4 confirmed and 2 non-confirmed PSA responses ( > 50% decrease) were observed. Conclusions: The RP2D of BIDW ModraDoc006/r in mCRPC was established as 30-20/200-100 mg. These results are encouraging for further development of ModraDoc006/r as a convenient, safe and effective alternative to IV docetaxel for mCRPC patients. A phase 2b study is currently being conducted. Clinical trial information: NCT03136640.

A Phase I Dose Escalation Study of Once-Weekly Oral Administration of Docetaxel as ModraDoc001 Capsule or ModraDoc006 Tablet in Combination with Ritonavir

PURPOSE

Oral bioavailability of docetaxel is poor. Absorption could be improved by development of pharmaceutical formulations based on docetaxel solid dispersions, denoted ModraDoc001 capsule and ModraDoc006 tablet (both 10 mg) and coadministration of ritonavir, an inhibitor of CYP3A4 and P-glycoprotein. In this study, the safety, MTD, recommended phase II dose (RP2D), pharmacokinetics, and preliminary antitumor activity of oral docetaxel combined with ritonavir in a once-weekly continuous schedule was investigated.

PATIENTS AND METHODS

Patients with metastatic solid tumors were included. Dose escalation was performed using a classical 3+3 design. Pharmacokinetic sampling was performed for up to 48 hours after drug administration. Safety was evaluated using CTCAE v3.0. Antitumor activity was assessed according to RECIST v1.0.

RESULTS

Sixty-seven patients were treated at weekly docetaxel dosages ranging from 30 to 80 mg in combination with 100- or 200-mg ritonavir. Most common toxicities were nausea, vomiting, diarrhea and fatigue, mostly of grade 1-2 severity. No hypersensitivity reactions were observed. The area under the plasma concentration-time curve (AUC_0-48) of docetaxel at the RP2D of once-weekly 60-mg ModraDoc001 capsule with 100-mg ritonavir was 1,000 ± 687 ng/mL/hour and for once-weekly 60-mg ModraDoc006 tablet with 100-mg ritonavir, the AUC_0-48 was 1,790 ± 819 ng/mL/hour. Nine partial responses were reported as best response to treatment.

CONCLUSIONS

Oral administration of once-weekly docetaxel as ModraDoc001 capsule or ModraDoc006 tablet in combination with ritonavir is feasible. The RP2D for both formulations is 60-mg ModraDoc with 100-mg ritonavir. Antitumor activity is considered promising.

Phase I and pharmacological trial of lapatinib in combination with gemcitabine in patients with advanced breast cancer

Background Lapatinib has proven efficacy as monotherapy and in combination with capecitabine in patients with metastatic breast cancer (MBC) overexpressing HER2 and/or EGFR. Gemcitabine also has anti-tumor activity in MBC and a favourable toxicity profile. In this phase I study lapatinib and gemcitabine were combined. Methods Female patients with advanced BC were given lapatinib once daily (QD) in 28-day cycles with gemcitabine administered on day 1, 8 and 15. Physical examinations, vital signs and blood sampling for hematology, clinical chemistry and pharmacokinetics (PK) and radiological assessments of disease were performed at regular intervals. Results In total, 33 patients were included. Six dose-limiting toxicities were observed, mostly grade 3 increases in liver function tests. Most common toxicities were fatigue (73 %), nausea (70 %), diarrhea (58 %), increases in ALAT and ASAT (55 and 52 %, respectively) and rash (46 %). The maximum tolerated dose was lapatinib 1250 mg QD with gemcitabine 1000 mg/m². Lapatinib and gemcitabine PK did not appear to be influenced by each other. Anti-tumor activity was observed with one patient (4 %) showing complete response and six (23 %) partial response. Conclusion Despite a slightly increased toxicity profile compared to their respective monotherapies, lapatinib and gemcitabine can be safely combined while showing signs of anti-tumor activity.

The effect of Echinacea purpurea on the pharmacokinetics of docetaxel

AIMS

The herbal medicine Echinacea purpurea (E. purpurea) has been shown to induce cytochrome P450 3A4 (CYP3A4) both in vitro and in humans. This study explored whether E. purpurea affects the pharmacokinetics of the CYP3A4 substrate docetaxel in cancer patients.

METHODS

Ten evaluable cancer patients received docetaxel (135 mg, 60 min IV infusion) before intake of a commercially available E. purpurea extract (20 oral drops three times daily) and 3 weeks later after a 14 day supplementation period with E. purpurea. In both cycles, pharmacokinetic parameters of docetaxel were determined.

RESULTS

Before and after supplementation with E. purpurea, the mean area under the plasma concentration-time curve of docetaxel was 3278 ± 1086 and 3480 ± 1285 ng ml(-1) h, respectively. This result was statistically not significant. Nonsignificant alterations were also observed for the elimination half-life (from 30.8 ± 19.7 to 25.6 ± 5.9 h, P = 0.56) and maximum plasma concentration of docetaxel (from 2224 ± 609 to 2097 ± 925 ng ml(-1) , P = 0.30).

CONCLUSIONS

The multiple treatment of E. purpurea did not significantly alter the pharmacokinetics of docetaxel in this study. The applied E. purpurea product at the recommended dose may be combined safely with docetaxel in cancer patients.

Phase I study of weekly oral docetaxel (ModraDoc001) plus ritonavir in patients with advanced solid tumors

2550

Background: ModraDoc001 is a novel oral formulation containing docetaxel as a solid dispersion. Oral administration of docetaxel is feasible in combination with the CYP3A4 inhibitor ritonavir. Objectives were to determine the safety, maximum tolerated dose (MTD) and pharmacokinetics (PK) of weekly oral docetaxel (as ModraDoc001) in combination with ritonavir. Methods: Patients with advanced solid tumors, WHO PS ≤ 2, no concomitant use of MDR or CYP3A modulating drugs, adequate bone marrow (ANC ≥ 1.5x109 /L), liver (bilirubin ≤ 1.5xULN, ALAT/ASAT ≤ 2.5xULN) and renal function (creatinine ≤ 1.5xULN or clearance ≥ 50 ml/min) were eligible. Docetaxel (ModraDoc001 10mg capsule) and ritonavir (Norvir 100mg) were simultaneously given once weekly in a ‘3+3 cohort’ dose escalation design. MTD was defined as the highest dose resulting in <1/6 probability of causing a dose limiting toxicity in the first 4 weeks of treatment. This cohort was expanded with 6 patients. PK was determined on days 1 and 8. Results: 40 patients (25 male, 35 evaluable for safety) were enrolled in 6 dose levels (30/100, 40/100, 60/100, 80/100, 60/200 and 80/200 mg docetaxel/ritonavir). Common treatment related adverse events in the 4 highest dose levels were diarrhea (68%), nausea (62%) and fatigue (62%), mostly CTC grade 1-2 (80%, 95% and 73% respectively). Five patients experienced a DLT (grade 3 diarrhea (4), elevated ASAT/ALAT (1), grade 4 dehydration and grade 3 mucositis (1), grade 3 fatigue (2)). The MTD was 60 mg/200 mg docetaxel/ritonavir. Partial remission was seen in 4 patients (CUP, NSCLC, gastric and mamma ca) and sustained stable disease in 15 patients (6x NSCLC). Both drugs were rapidly absorbed after oral administration. Mean Tmax was 2.0 hours (CV=73%) for docetaxel. Cmax and AUC of docetaxel increased less than proportionally with dose to 162 ng/ml (CV= 67%) and 1615 ng/ml*hr (CV= 81%), respectively, in 15 patients at the MTD. Conclusions: At the MTD (once weekly 60 mg docetaxel and 200 mg ritonavir) ModraDoc001 is safe, well tolerated and shows encouraging antitumor activity. The exposure of docetaxel with this regimen is comparable to weekly intravenous administration of 35 mg/m2 docetaxel. Phase II studies in solid tumors are planned.

Abstract 761: Phase I interaction study of docetaxel with supplementation of St. John's wort

Introduction St. John's wort (SJW, Hypericum perforatum) is a herbal antidepressant, which is often used by cancer patients. In healthy volunteers, SJW has previously been shown to induce hepatic CYP3A4 using the selective CYP3A4 substrate midazolam (Wang et al., 2001). In cancer patients, CYP3A4 induction by SJW could result in a decreased exposure to anticancer drugs metabolized by CYP3A4 (e.g. docetaxel), possibly resulting in a decreased therapeutic effect. Induction of docetaxel metabolism by the SJW constituent hyperforin has already been established in vitro (Komoroski et al., 2005). This pharmacokinetic interaction, however, has never been studied before in a clinical setting. Therefore, the aim of this study was to assess the effects of SJW on the pharmacokinetics of docetaxel in cancer patients. Methods In a one-sequence crossover study performed at the Netherlands Cancer Institute and approved by the Institute's Medical Ethical Committee, ten cancer patients received two cycles of docetaxel (135 mg, 60 min IV infusion). Seven days after cycle 1 (docetaxel alone), a commercial SJW extract in a recommended dose of one tablet (containing 300 mg SJW extract) three times daily was supplemented for fourteen days. After this supplementation period, cycle 2 of docetaxel was administered. During cycle 1 and cycle 2, blood samples were collected from 0-48 h after the start of the docetaxel infusion for pharmacokinetic analysis of docetaxel. Docetaxel plasma concentrations were determined by a validated LC-MS/MS assay (Kuppens et al., 2005). The pharmacokinetic endpoint for docetaxel was the area under the plasma concentration-time curve from time 0 to 48 h (AUC0-48), reflecting systemic exposure to docetaxel. By comparing the AUC0-48 of docetaxel in cycle 1 and 2, the effect of SJW on docetaxel pharmacokinetics was determined. Statistical analysis was performed with a paired Student's t test (α = 0.05). Differences in AUC0-48 between cycle 1 and 2 were considered clinically relevant if the 90% CI of the geometric mean ratio was not completely within no-effect limits of 0.80-1.25. Results (preliminary) In eight evaluable patients, supplementation of SJW decreased the mean docetaxel AUC0-48 from 2745 ± 650 to 2364 ± 483 ng/mL*h (p = 0.048, geometric mean ratio 0.86 (90% CI: 0.81-0.92)). Conclusion In this study, the observed decrease of docetaxel AUC0-48 after SJW administration was statistically significant, possibly even clinically relevant. This result indicates that concomitant use of the present SJW formulation in the recommended dose may decrease the therapeutic efficacy of docetaxel and presumably also other anticancer drugs primarily metabolized by CYP3A4. Acknowledgements This study was supported by the Dutch Cancer Society grant UU 2007-3795.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 761. doi:1538-7445.AM2012-761

Coadministration of ritonavir strongly enhances the apparent oral bioavailability of docetaxel in patients with solid tumors

PURPOSE

To enhance the systemic exposure to oral docetaxel by coadministration of ritonavir, an efficacious inhibitor of CYP 3A4 with minor P-glycoprotein inhibiting effects, in patients with cancer.

EXPERIMENTAL DESIGN

A proof-of-concept study was carried out in 12 patients with solid tumors. The first cohort of patients (n = 4) received 10 mg and the subsequent cohort (n = 8) 100 mg of oral docetaxel, coadministered with 100 mg oral ritonavir randomized simultaneously or ritonavir given 60 minutes before docetaxel on days 1 and 8. On day 15 or 22, patients received 100 mg i.v. docetaxel.

RESULTS

The area under the plasma concentration-time curve in patients who received 10 mg oral docetaxel in combination with ritonavir was low, and the dose could safely be increased to 100 mg. The area under the plasma concentration-time curve in patients who received 100 mg oral docetaxel combined with ritonavir simultaneously or ritonavir given 60 minutes before docetaxel was 2.4 +/- 1.5 and 2.8 +/- 1.4 mg/h/L, respectively, compared with 1.9 +/- 0.4 mg/h/L after i.v. docetaxel. The apparent oral bioavailability of docetaxel combined with ritonavir simultaneously or ritonavir given 60 minutes before docetaxel was 131% +/- 90% and 161% +/- 91%, respectively. The oral combination of docetaxel and ritonavir was well tolerated.

CONCLUSION

Coadministration of ritonavir significantly enhanced the apparent oral bioavailability of docetaxel. These data are promising and form the basis for further development of a clinically applicable oral formulation of docetaxel combined with ritonavir.

Phase I Pharmacokinetic Study of the Safety and Tolerability of Lapatinib (GW572016) in Combination with Oxaliplatin/Fluorouracil/Leucovorin (FOLFOX4) in Patients with Solid Tumors

PURPOSE

This phase I study was designed to determine the optimally tolerated regimen (OTR), safety, and clinical activity of lapatinib in combination with FOLFOX4 [oxaliplatin/leucovorin/5-fluorouracil (5-FU)] in patients with solid tumors. Furthermore, the pharmacokinetics of lapatinib, oxaliplatin, and 5-FU when given alone and in combination were evaluated.

EXPERIMENTAL DESIGN

This study was conducted in two parts. Part 1 was designed to determine the OTR and part 2 was the pharmacokinetic part of the study. Lapatinib was administered once daily for the entire duration of the study. Leucovorin and oxaliplatin were given concurrently over 2 h as an i.v. infusion, after which 5-FU was given as a bolus followed by continuous infusion over 22 h on day 1. 5-FU and leucovorin administration were repeated in an identical manner on day 2. Cycles were repeated every 2 weeks. Once the OTR was determined, it was to become the dose level for patients included in the pharmacokinetic part of the study.

RESULTS

A total of 34 patients was treated in this study. No dose-limiting toxicities were observed and the OTR was established at 1,500 mg/d lapatinib in combination with the standard FOLFOX4 regimen. Nonhematologic toxicities consisted mainly of nausea, diarrhea, vomiting, fatigue, neuropathy, and mucositis. The most important hematologic toxicity was neutropenia. No drug-drug interactions between lapatinib and the FOLFOX4 regimen were observed.

CONCLUSION

Lapatinib can be safely administered in combination with the standard FOLFOX4 regimen. Further studies are warranted to explore the potential additive antitumor effect of lapatinib in combination with the FOLFOX4 regimen.

Citalopram Serum and Milk Levels in Mother and Infant During Lactation

We present a case of intensified therapeutic drug monitoring (TDM) of citalopram in mother and newborn infant after clinically observed selective serotonin reuptake inhibitor (SSRI)-associated symptoms 2 weeks until 2 months after delivery. The SSRI-associated symptoms observed in the infant (up to 3 weeks after delivery) were irregular breathing, sleep disorders, hypotonia, and hypertonia. We conclude that the SSRI-associated symptoms in the infant represent citalopram withdrawal effects rather than side effects caused by breastfeeding. This case illustrates the importance of a flexible TDM program and a multidisciplinary approach in a hospital setting to deal with cases of drug-associated adverse effects, such as SSRI withdrawal effects.

[Diagnostic image (239). A male newborn with a skin lesion on a knee]

Cutis marmorata teleangiectatica congenita was diagnosed in a male neonate.

Enlarged nuchal translucency and low serum protein concentrations as possible markers for Zellweger syndrome

We present a case of a fetus in which an enlarged nuchal translucency was detected at 12 weeks' gestation. The karyotype was normal. Subsequent ultrasound examination showed no obvious fetal abnormalities apart from a mild pericardial effusion. Serum screening revealed very low concentrations of estriol and human chorionic gonadotropin. After birth the diagnosis of Zellweger syndrome was made. Nuchal translucency screening, estriol level identification and detailed ultrasound scanning may help to identify fetuses affected by this syndrome.