Safety Study of PLX3397 and Paclitaxel in Patients With Advanced Solid Tumors

Study Overview
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Brief Summary
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This was a 3-part study designed to explore the safety and tolerability of escalating doses of PLX3397 with weekly paclitaxel to establish a recommended Phase 2 dose (RP2D), to confirm RP2D in participants with advanced non-resectable solid tumors, and to determine the efficacy of PLX3397 600 mg twice daily (BID) administered in combination with weekly paclitaxel in participants with advanced, metastatic or non-resectable, platinum-resistant or -refractory epithelial ovarian cancer, primary peritoneal cancer, or fallopian tube cancer.

Official Title
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A Phase 1b Study to Assess the Safety of PLX3397 and Paclitaxel in Patients With Advanced Solid Tumors

Conditions
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Solid Tumors

Intervention / Treatment
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* Drug: PLX3397
* Drug: Paclitaxel


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients with: Part 1 (enrollment closed): an advanced, incurable solid tumor Part 2 (enrollment closed): an advanced, incurable solid tumor for whom a taxane would be considered a reasonable chemotherapy option Part 3 (enrollment closed): advanced, metastatic or non-resectable epithelial ovarian cancer, primary peritoneal cancer or fallopian tube cancer with platinum-resistant cancer, defined as disease that responded to a platinum-containing chemotherapy regimen, but demonstrated recurrence within six months following the completion of that platinum-containing regimen, OR platinum-refractory cancer, defined as disease failed to achieve at least a partial response to a platinum-containing regimen (i.e., stable disease or actual disease progression), AND have not been treated with a taxane within six months of Cycle 1 Day 1 (C1D1), AND have not been treated with weekly paclitaxel after first-line treatment in which weekly paclitaxel plus a platinum is permitted Part 3: Patients must have target (≥2 cm diameter) or non-target lesion cancer that is accessible for core biopsies before starting on study and after one cycle of treatment. Patients with stable brain metastases are eligible for this trial. However, patients must not have required steroid treatment for their brain metastases within 30 days of Screening. Bone-directed therapy (e.g., bisphosphonates or denosumab) is permitted. Washout from any prior investigational therapy of at least five times the T1/2 prior to C1D1 Washout from any prior biologic or targeted therapy at least 4 weeks or five times the plasma half-life (T1/2) (whichever is shorter) prior to C1D1 Washout from prior chemotherapy of at least 2 weeks or 1 elimination half-life, whichever is longer, prior to C1D1 Washout from prior hormonal therapy of at least 2 weeks prior to C1D1 Washout of at least 2 weeks from the most recent radiation treatment prior to C1D1 Resolution of all prior treatment-related toxicities to Grade 1 or less, except for Grade 2 fatigue or alopecia prior to C1D1 Age eighteen years or older Eastern Cooperative Oncology Group (ECOG) performance status 0-2, inclusive Anticipated life expectancy of at least 12 weeks Adequate bone marrow reserve: absolute neutrophil count (ANC) ≥1500/mm3, platelets ≥100,000/mm3 Adequate renal function: serum creatinine <1.5 x ULN or calculated creatinine clearance (CrCl) >60 mL/min using Cockcroft-Gault formula Adequate hepatic function: aspartate aminotransferase (AST) and alanine aminotransferase (ALT) <2.5 x upper limit of normal (ULN), Total and Direct Bilirubin <1.5 x ULN. However, in the presence of liver metastases, AST and ALT must be <5 x ULN Cardiac ejection fraction ≥50%, and QT interval corrected by Fridericia's formula (QTcF) <450 ms (males) or <470 ms (females) on electrocardiogram (ECG) at Baseline. Able to swallow capsules and maintain adequate hydration Ability to give written informed consent and willing to comply with the requirements of the protocol; and for Part 3, to give written informed consent for 2 cancer biopsy procedures Women of child-bearing potential must agree to use an effective method of birth control during treatment and for three months after receiving their last dose of study drug. Fertile men must also agree to use an acceptable method of birth control while on study drug and for at least 3 months after last dose. Exclusion Criteria: Presence of an active secondary malignancy. Patients with a non-melanomatous, in situ malignancy or disease that is completely resectable with surgery may be considered after discussion with the Medical Monitor Patients with a completely treated prior malignancy with no evidence of disease for ≥3 years are eligible Refractory nausea and vomiting, malabsorption, external biliary shunt or significant small bowel resection that would preclude adequate absorption of PLX3397 Ongoing treatment with any other investigational therapy Prior anaphylactic or severe hypersensitivity reaction to paclitaxel or Cremophor-containing agent. Persistent grade 2 fatigue at Baseline. Severe, concurrent illness including congestive heart failure, significant cardiac disease and uncontrolled hypertension, that would likely prevent the patient from being able to comply with the study protocol Active untreated infection Known chronic active Hepatitis B or C, or HIV infection The presence of a medical or psychiatric condition that, in the opinion of the Principal Investigator, makes the patient inappropriate for inclusion in this study.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Non-Randomized
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Part 1<br>Open-label, sequential PLX3397 single-agent dose escalation in combination with paclitaxel in approximately 30 patients with advanced solid tumors. Enrollment completed. (Closed to recruitment) | Drug: PLX3397<br>* PLX3397 tablets, 200mg<br>* Other names: Pexidartinib;Drug: Paclitaxel<br>* Paclitaxel IV<br>* Other names: Onxol;|
| Experimental: Part 2<br>Extension cohort at the RP2D of single-agent PLX3397 in combination with paclitaxel in approximately 30 patients in advanced solid tumors. Enrollment completed. (Closed to recruitment) | Drug: PLX3397<br>* PLX3397 tablets, 200mg<br>* Other names: Pexidartinib;Drug: Paclitaxel<br>* Paclitaxel IV<br>* Other names: Onxol;|
| Experimental: Part 3<br>Extension cohort at the RP2D of single-agent PLX3397 in combination with paclitaxel in approximately 30 patients with advanced, metastatic, or non-resectable, platinum-resistant or -refractory epithelial ovarian cancer, primary peritoneal cancer, or fallopian tube cancer. (Closed to recruitment) | Drug: PLX3397<br>* PLX3397 tablets, 200mg<br>* Other names: Pexidartinib;Drug: Paclitaxel<br>* Paclitaxel IV<br>* Other names: Onxol;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Percentage of Participants With Treatment-emergent Adverse Events (>10%) Classified by Preferred Term Following PLX3397 Administered in Combination With Paclitaxel (Parts 1 and 2) (Safety Population) | Treatment-emergent adverse events (TEAEs) reported by >10% of all participants in Parts 1 and 2 are reported. | From post first dose up to 28 days after the last dose, up to 5 years 9 months | 
| Percentage of Participants With TEAEs (>10%) Classified by Preferred Term Following PLX3397 Administered in Combination With Paclitaxel (Part 3) (Safety Population) | Treatment-emergent adverse events (TEAEs) reported by >10% of all participants in Part 3 are reported. | From post first dose up to 28 days after the last dose, up to 5 years 9 months | 
| Best Overall Tumor Response Based on RECIST V1.1 Following PLX3397 Administered in Combination With Paclitaxel (Parts 1 and 2) (Efficacy Evaluable Population) | Best overall tumor response (complete response [CR], partial response [PR], stable disease [SD], progressive disease [PD]) is reported, including participants who were not evaluable (NE). RECIST v1.1 for target lesions are assessed by magnetic resonance imaging, computed tomography, or positron emission tomography-computed tomography and are summarized as: CR, Disappearance of all target lesions. Any pathological lymph nodes must have reduction in short axis to <10 mm; PR, At least a 30% decrease in the sum of diameters of target lesions, taking as reference the baseline sum diameters; PD, at least a 20% increase in the sum of diameters of target lesions, taking as reference the smallest sum on study (includes the baseline sum). In addition, the sum must also demonstrate an absolute increase of at least 5 mm; SD, Neither sufficient shrinkage to qualify for PR nor sufficient increase to qualify for PD, taking as reference the smallest sum diameters while on study. | From post first dose up to 5 years 9 months post dose | 
| Best Overall Tumor Response Based on RECIST V1.1 Following PLX3397 Administered in Combination With Paclitaxel (Part 3) (Efficacy Evaluable Population) | Best overall tumor response (complete response [CR], partial response [PR], stable disease [SD], progressive disease [PD]) is reported, including participants who were not evaluable (NE). RECIST v1.1 for target lesions are assessed by magnetic resonance imaging, computed tomography, or positron emission tomography-computed tomography and are summarized as: CR, Disappearance of all target lesions. Any pathological lymph nodes must have reduction in short axis to <10 mm; PR, At least a 30% decrease in the sum of diameters of target lesions, taking as reference the baseline sum diameters; PD, at least a 20% increase in the sum of diameters of target lesions, taking as reference the smallest sum on study (includes the baseline sum). In addition, the sum must also demonstrate an absolute increase of at least 5 mm; SD, Neither sufficient shrinkage to qualify for PR nor sufficient increase to qualify for PD, taking as reference the smallest sum diameters while on study. | From 26 days (CR and PR) and 54 days (SD) up to 5 years 9 months post dose | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Percentage of Participants With PLX3397-Related Treatment-emergent Adverse Events (>10%) by Preferred Term (Parts 1 and 2) (Safety Analysis Set) |  | From post first dose up to 28 days after the last dose, up to 5 years 9 months | 
| Percentage of Participants With Paclitaxel-Related Treatment-emergent Adverse Events (>10%) by Preferred Term (Parts 1 and 2) (Safety Analysis Set) |  | From post first dose up to 28 days after the last dose, up to 5 years 9 months | 
| Percentage of Participants With PLX3397- and/or Paclitaxel-Related TEAEs (>10%) by Preferred Term (Part 3) (Safety Analysis Set) |  | From post first dose up to 28 days after the last dose, up to 5 years 9 months | 
| Duration of Response Following PLX3397 Administered in Combination With Paclitaxel (Parts 1 and 2) (Efficacy Evaluable Population) |  | From the date of initial response until disease progression or death, whichever occurs first, up to 5 years 9 months post dose | 
| Duration of Response Following PLX3397 Administered in Combination With Paclitaxel (Part 3) (Efficacy Evaluable Population) |  | From the date of initial response until disease progression or death, whichever occurs first, up to 5 years 9 months post dose | 
| Progression-free Survival Following PLX3397 Administered in Combination With Paclitaxel (Part 3) (Efficacy Evaluable Population) | Progression-free survival (PFS) is defined as the number of days from the start of therapy (i.e. Cycle 1 Day 1) to the date of first documented disease progression/relapse or death, whichever occurs first. If the disease progression/relapse does not occur, PFS will be censored as of the date of their last evaluable tumor assessments. | From the first day of treatment to the first documented disease progression or date of death, whichever occurred first, up to 5 years 9 months post dose | 
| A Summary of Pharmacokinetic Parameter (Tmax) Following Exposure to PLX3397 (Parts 1 and 3) |  | Cycle 1, Day 15 | 
| A Summary of Pharmacokinetic Parameter (Cmax) Following Exposure to PLX3397 (Parts 1 and 3) |  | Cycle 1, Day 15 | 
| A Summary of Pharmacokinetic Parameters (AUC[0-4h], AUC[0-6h], and AUC[0-12h]) Following Exposure to PLX3397 (Parts 1 and 3) |  | Cycle 1, Day 15 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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advanced, incurable solid tumors