PLX038 (PEGylated SN38) and Rucaparib in Solid Tumors and Small Cell Cancers

Phase 1

Completed

Conditions: Small Cell Lung Cancer
Extra-Pulmonary Small Cell Carcinomas

Interventions: Drug: PLX038
Drug: Rucaparib
Drug: Ondansetron

Registration Number: NCT04209595

Lead Sponsor: National Cancer Institute (NCI)

Brief Summary: Background:

Drugs known as poly-adenosine diphosphate ribose polymerase (PARP) inhibitors are known to help stop tumor growth in patients with breast, ovarian cancers and many other cancers including prostate and pancreatic cancers. Many research studies done in animals and human cells have shown that these types of drugs can improve how well chemotherapy works. Standard chemotherapy can be too toxic to be combined with PARP inhibitors. In this study, we use a new form of chemotherapy called PLX038 (PEGylated SN38) to see if it can be safely combined with PARP inhibitors to shrink tumors.

Objective:

To find a safe combination of PLX038 and rucaparib, and to see if this mix will cause tumors to shrink.

Eligibility:

People age 18 and older with solid tumors, small cell lung cancer (SCLC), or small cell cancer outside their lungs.

Design:

Participants will be screened with:

Physical exam

Blood tests

Records of their diagnosis (or they will have a tumor biopsy).

A review of their symptoms and medications.

A review of their ability to perform their normal activities.

Electrocardiograms, to measure the electrical activity of the heart.

Computed tomography (CT) scans of the chest, abdomen, and pelvis. CT scans are a series of X-rays.

Participants will get PLX038 by intravenous catheter on Day 1 of each cycle (1 cycle = 21 days). For this, a small plastic tube is put into an arm vein. They will take rucaparib twice daily by mouth on Days 3 to 19 of each cycle. They will keep a medicine diary.

Participants may give a hair sample. They may have optional tumor biopsies.

Screening tests are repeated throughout the study.

About 30 days after treatment ends, participants will have a safety follow-up visit. They will give blood samples, talk about their health, and get a physical exam. Then they will be called or emailed every 6 months....

Detailed Description: Background:

* We hypothesize that a dose-escalation strategy that incorporates tumor targeted deoxyribonucleic acid (DNA)-damaging chemotherapy and DNA-damage response (DDR) inhibitors could allow safe and effective administration of DNA damage response (DDR) inhibitor-chemotherapy combination.

* PLX038 is a PEGylated conjugate of SN38 with improved properties including increased solubility, higher exposure and longer half-life. SN-38 is the active metabolite of CPT-11 (irinotecan) that inhibits topoisomerase 1 (Top1) and causes DNA strand breakage. As a specific DNA damaging agent, SN-38 enhances cell kill in tumors deficient in the DNA-damage response and when combined with inhibitors of the DDR.

* Rucaparib is a potent oral poly ADP ribose polymerase (PARP) inhibitor that is approved for the maintenance treatment of participants with recurrent epithelial ovarian, fallopian tube, or primary peritoneal cancer who are in a complete or partial response to platinum-based chemotherapy.

* We hypothesize that the combination of PLX038 plus rucaparib is more efficacious than either agent alone.

Objectives:

* Phase I: To identify the maximum tolerated dose (MTD) of PLX038 in combination with rucaparib.

* Phase II: To assess the efficacy with respect to clinical benefit rate (CBR) (CR+PR+SD) for 4 months according to Response Evaluation Criteria (RECIST 1.1) of a combination of PLX038 and rucaparib in participants with small cell lung cancer and extra-pulmonary small cell carcinomas.

Eligibility:

* Subjects with histologically confirmed solid tumors (Phase I) OR histologically or cytologically confirmed small cell lung cancer (SCLC) (Phase II) OR histologically or cytologically confirmed extra-pulmonary small cell carcinomas (Phase II).

* Age greater than or equal to 18 years

* Subjects must have evaluable, or measurable disease.

* Eastern Cooperative Oncology Group (ECOG) performance status less than or equal to 2

* Adequate organ function

Design:

* This is an open label Phase I/II trial accruing initially one cohort to determine maximum tolerated dose (MTD) of combined treatment of PLX038 and rucaparib (Phase I); and to examine the safety and efficacy of PLX038 in combination with rucaparib in the following cohort (Phase II).

* PLX038 will be administered by intravenous (IV) infusion on day 1 of every 21-days cycle, rucaparib will be administered by mouth (PO) twice daily on days 6 to 19 of every cycle.

* Treatment will continue until progression or unacceptable toxicity.

* Biomarkers of participant response to treatment will be investigated in an exploratory manner pre- and post-treatment.

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 10

Inclusion Criteria

Not provided

Exclusion Criteria

Not provided

Study & Design

Study Type: INTERVENTIONAL

Study Design: SEQUENTIAL

Arm && Interventions

Group	Intervention	Description
Phase IIB Arm 2	Ondansetron	Phase IIB Participants with extra-pulmonary small cell carcinomas enrolled at the maximum tolerated dose (MTD) of PLX038 (PEGylated SN38) and rucaparib after the MTD of PLX038 and rucaparib is established. Level 2, PLX038, every 3 weeks, 1.3 g/m\^2, intravenous (IV); Rucaparib, days 3-19 twice a day (BID), total dose, 600 mg by mouth (PO); Level 3, PLX038, every 3 weeks, 1.7 g/m\^2, intravenous (IV); Rucaparib, days 3-19 twice a day (BID), total dose, 600 mg by mouth (PO); Level 4, PLX038, every 3 weeks, 2.3 g/m\^2, intravenous (IV); Rucaparib, days 3-19 twice a day (BID), total dose, 600 mg by mouth (PO); Level 2A PLX038, every 3 weeks, 1.3 g/m\^2, intravenous (IV); Rucaparib, days 5-19 twice a day (BID), total dose, 400 mg by mouth (PO); and/or Level 3A. PLX038, every 3 weeks, 1.3 g/m\^2, intravenous (IV); Rucaparib, days 5-19 twice a day (BID), total dose, 600 mg by mouth (PO).
Phase I Arm 1 Level -1A, PLX038 (PEGylated SN38) 1.3 g/m^2 and Rucaparib 200 mg	PLX038	Phase I - Participants with solid tumors enrolled to PLX038 (PEGylated SN38) and rucaparib escalation dose levels. PLX038, every 3 weeks, 1.3 g/m\^2, intravenous (IV); Rucaparib, days 5-19 twice a day (BID), total dose, 200 mg by mouth (PO)
Phase I Arm 1 Level 1, PLX038 (PEGylated SN38) 1.3 g/m^2 and Rucaparib 400 mg	PLX038	Phase I - Participants with solid tumors enrolled to PLX038 (PEGylated SN38) and rucaparib escalation dose levels. PLX038, every 3 weeks, 1.3 g/m\^2, intravenous (IV); Rucaparib, days 3-19 twice a day (BID), total dose, 400 mg by mouth (PO)
Phase I - Arm 1 Level 1A, PLX038 (PEGylated SN38) 1.3 g/m^2 and Rucaparib 300 mg	PLX038	Phase I Participants with solid tumors enrolled to PLX038 (PEGylated SN38) and rucaparib escalation dose levels. PLX038, every 3 weeks, 1.3 g/m\^2, intravenous (IV); Rucaparib, days 5-19 twice a day (BID), total dose, 300 mg by mouth (PO)
Phase IIA Arm 2	PLX038	Phase IIA Participants with small cell lung cancer (SCLC) enrolled at the maximum tolerated dose (MTD) of PLX038 (PEGylated SN38) and rucaparib after the MTD of PLX038 and rucaparib is established. Level 2, PLX038, every 3 weeks, 1.3 g/m\^2, intravenous (IV); Rucaparib, days 3-19 twice a day (BID), total dose, 600 mg by mouth (PO); Level 3, PLX038, every 3 weeks, 1.7 g/m\^2, intravenous (IV); Rucaparib, days 3-19 twice a day (BID), total dose, 600 mg by mouth (PO); Level 4, PLX038, every 3 weeks, 2.3 g/m\^2, intravenous (IV); Rucaparib, days 3-19 twice a day (BID), total dose, 600 mg by mouth (PO); Level 2A PLX038, every 3 weeks, 1.3 g/m\^2, intravenous (IV); Rucaparib, days 5-19 twice a day (BID), total dose, 400 mg by mouth (PO); and/or Level 3A. PLX038, every 3 weeks, 1.3 g/m\^2, intravenous (IV); Rucaparib, days 5-19 twice a day (BID), total dose, 600 mg by mouth (PO).
Phase IIB Arm 2	PLX038	Phase IIB Participants with extra-pulmonary small cell carcinomas enrolled at the maximum tolerated dose (MTD) of PLX038 (PEGylated SN38) and rucaparib after the MTD of PLX038 and rucaparib is established. Level 2, PLX038, every 3 weeks, 1.3 g/m\^2, intravenous (IV); Rucaparib, days 3-19 twice a day (BID), total dose, 600 mg by mouth (PO); Level 3, PLX038, every 3 weeks, 1.7 g/m\^2, intravenous (IV); Rucaparib, days 3-19 twice a day (BID), total dose, 600 mg by mouth (PO); Level 4, PLX038, every 3 weeks, 2.3 g/m\^2, intravenous (IV); Rucaparib, days 3-19 twice a day (BID), total dose, 600 mg by mouth (PO); Level 2A PLX038, every 3 weeks, 1.3 g/m\^2, intravenous (IV); Rucaparib, days 5-19 twice a day (BID), total dose, 400 mg by mouth (PO); and/or Level 3A. PLX038, every 3 weeks, 1.3 g/m\^2, intravenous (IV); Rucaparib, days 5-19 twice a day (BID), total dose, 600 mg by mouth (PO).
Phase I Arm 1 Level -1A, PLX038 (PEGylated SN38) 1.3 g/m^2 and Rucaparib 200 mg	Rucaparib	Phase I - Participants with solid tumors enrolled to PLX038 (PEGylated SN38) and rucaparib escalation dose levels. PLX038, every 3 weeks, 1.3 g/m\^2, intravenous (IV); Rucaparib, days 5-19 twice a day (BID), total dose, 200 mg by mouth (PO)
Phase I Arm 1 Level -1A, PLX038 (PEGylated SN38) 1.3 g/m^2 and Rucaparib 200 mg	Ondansetron	Phase I - Participants with solid tumors enrolled to PLX038 (PEGylated SN38) and rucaparib escalation dose levels. PLX038, every 3 weeks, 1.3 g/m\^2, intravenous (IV); Rucaparib, days 5-19 twice a day (BID), total dose, 200 mg by mouth (PO)
Phase I - Arm 1 Level 1A, PLX038 (PEGylated SN38) 1.3 g/m^2 and Rucaparib 300 mg	Ondansetron	Phase I Participants with solid tumors enrolled to PLX038 (PEGylated SN38) and rucaparib escalation dose levels. PLX038, every 3 weeks, 1.3 g/m\^2, intravenous (IV); Rucaparib, days 5-19 twice a day (BID), total dose, 300 mg by mouth (PO)
Phase I Arm 1 Level 1, PLX038 (PEGylated SN38) 1.3 g/m^2 and Rucaparib 400 mg	Rucaparib	Phase I - Participants with solid tumors enrolled to PLX038 (PEGylated SN38) and rucaparib escalation dose levels. PLX038, every 3 weeks, 1.3 g/m\^2, intravenous (IV); Rucaparib, days 3-19 twice a day (BID), total dose, 400 mg by mouth (PO)
Phase I Arm 1 Level 1, PLX038 (PEGylated SN38) 1.3 g/m^2 and Rucaparib 400 mg	Ondansetron	Phase I - Participants with solid tumors enrolled to PLX038 (PEGylated SN38) and rucaparib escalation dose levels. PLX038, every 3 weeks, 1.3 g/m\^2, intravenous (IV); Rucaparib, days 3-19 twice a day (BID), total dose, 400 mg by mouth (PO)
Phase I - Arm 1 Level 1A, PLX038 (PEGylated SN38) 1.3 g/m^2 and Rucaparib 300 mg	Rucaparib	Phase I Participants with solid tumors enrolled to PLX038 (PEGylated SN38) and rucaparib escalation dose levels. PLX038, every 3 weeks, 1.3 g/m\^2, intravenous (IV); Rucaparib, days 5-19 twice a day (BID), total dose, 300 mg by mouth (PO)
Phase IIA Arm 2	Rucaparib	Phase IIA Participants with small cell lung cancer (SCLC) enrolled at the maximum tolerated dose (MTD) of PLX038 (PEGylated SN38) and rucaparib after the MTD of PLX038 and rucaparib is established. Level 2, PLX038, every 3 weeks, 1.3 g/m\^2, intravenous (IV); Rucaparib, days 3-19 twice a day (BID), total dose, 600 mg by mouth (PO); Level 3, PLX038, every 3 weeks, 1.7 g/m\^2, intravenous (IV); Rucaparib, days 3-19 twice a day (BID), total dose, 600 mg by mouth (PO); Level 4, PLX038, every 3 weeks, 2.3 g/m\^2, intravenous (IV); Rucaparib, days 3-19 twice a day (BID), total dose, 600 mg by mouth (PO); Level 2A PLX038, every 3 weeks, 1.3 g/m\^2, intravenous (IV); Rucaparib, days 5-19 twice a day (BID), total dose, 400 mg by mouth (PO); and/or Level 3A. PLX038, every 3 weeks, 1.3 g/m\^2, intravenous (IV); Rucaparib, days 5-19 twice a day (BID), total dose, 600 mg by mouth (PO).
Phase IIA Arm 2	Ondansetron	Phase IIA Participants with small cell lung cancer (SCLC) enrolled at the maximum tolerated dose (MTD) of PLX038 (PEGylated SN38) and rucaparib after the MTD of PLX038 and rucaparib is established. Level 2, PLX038, every 3 weeks, 1.3 g/m\^2, intravenous (IV); Rucaparib, days 3-19 twice a day (BID), total dose, 600 mg by mouth (PO); Level 3, PLX038, every 3 weeks, 1.7 g/m\^2, intravenous (IV); Rucaparib, days 3-19 twice a day (BID), total dose, 600 mg by mouth (PO); Level 4, PLX038, every 3 weeks, 2.3 g/m\^2, intravenous (IV); Rucaparib, days 3-19 twice a day (BID), total dose, 600 mg by mouth (PO); Level 2A PLX038, every 3 weeks, 1.3 g/m\^2, intravenous (IV); Rucaparib, days 5-19 twice a day (BID), total dose, 400 mg by mouth (PO); and/or Level 3A. PLX038, every 3 weeks, 1.3 g/m\^2, intravenous (IV); Rucaparib, days 5-19 twice a day (BID), total dose, 600 mg by mouth (PO).
Phase IIB Arm 2	Rucaparib	Phase IIB Participants with extra-pulmonary small cell carcinomas enrolled at the maximum tolerated dose (MTD) of PLX038 (PEGylated SN38) and rucaparib after the MTD of PLX038 and rucaparib is established. Level 2, PLX038, every 3 weeks, 1.3 g/m\^2, intravenous (IV); Rucaparib, days 3-19 twice a day (BID), total dose, 600 mg by mouth (PO); Level 3, PLX038, every 3 weeks, 1.7 g/m\^2, intravenous (IV); Rucaparib, days 3-19 twice a day (BID), total dose, 600 mg by mouth (PO); Level 4, PLX038, every 3 weeks, 2.3 g/m\^2, intravenous (IV); Rucaparib, days 3-19 twice a day (BID), total dose, 600 mg by mouth (PO); Level 2A PLX038, every 3 weeks, 1.3 g/m\^2, intravenous (IV); Rucaparib, days 5-19 twice a day (BID), total dose, 400 mg by mouth (PO); and/or Level 3A. PLX038, every 3 weeks, 1.3 g/m\^2, intravenous (IV); Rucaparib, days 5-19 twice a day (BID), total dose, 600 mg by mouth (PO).

Primary Outcome Measures

Name	Time	Method
Phase II: Clinical Benefit Rate	Disease progression at 4 months	Assess the efficacy with respect to clinical benefit rate (CBR) (Complete Response (CR)+ partial response (PR)+ stable disease (SD) for 4 months according to Response Evaluation Criteria (RECIST 1.1) of a combination of PLX038(PEGylated SN38) and rucaparib in previously treated participants with small cell lung cancer and extra-pulmonary small cell carcinomas. Response was assessed by the Response Evaluation Criteria in Solid Tumors (RECIST). CR is disappearance of all target lesions. Any pathological lymph nodes must have reduction in short axis to \<10 mm. PR is at least a 30% decrease in the sum of the diameters of target lesions, taking as reference the baseline sum of diameters. SD is neither sufficient shrinkage to qualify for PR nor sufficient increase to qualify for PD, taking as reference the smallest sum of diameters while on study. Progressive disease (PD) is at least a 20% increase in the sum of the diameters of target lesions, taking as reference the smallest sum on study.
Phase I: Maximum Tolerated Dose (MTD) of PLX038 (PEGylated SN38) in Combination With Rucaparib	One cycle, approximately 21 (+7) days	Maximum tolerated dose (MTD) of PLX038 (PEGylated SN38) in combination with rucaparib. The MTD is the dose level at which no more than 1 of 6 participants experience dose limiting toxicity (DLT) during the DLT evaluation period, and the dose below that at which at least 2 (of 6) participants have DLT as a result of the drug. A DLT is (if deemed drug-related) a Grade 4 neutropenia that does not resolve within 7 days; Grade 4 thrombocytopenia or grade 3 thrombocytopenia complicated with hemorrhage; Grade 4 anemia that does not resolve within 7 days despite optimal therapy; Inability to begin subsequent treatment course within 21 days of the scheduled date, due to study drug toxicity.

Secondary Outcome Measures

Name	Time	Method
Phase I and Phase II Grades 1-5 Serious and/or Non-serious Adverse Events Related to PLX038 (PEGylated SN38) and/or Rucaparib	Date first signed consent to date off study, approximately 21 months and 18 days; and 2 months and 5 days for each group respectively.	The safety of the treatment will be monitored, and any toxicities identified will be reported by type and grade. Toxicities were assessed by the Common Terminology Criteria for Adverse Events (CTCAE v5.0). A non-serious adverse event is any untoward medical occurrence. A serious adverse event is an adverse event or suspected adverse reaction that results in death, a life-threatening adverse drug experience, hospitalization, disruption of the ability to conduct normal life functions, congenital anomaly/birth defect or important medical events that jeopardize the patient or subject and may require medical or surgical intervention to prevent one of the previous outcomes mentioned. Grade 1 is mild, Grade 2 is moderate, Grade 3 is severe, Grade 4 is life-threatening, and Grade 5 is death related to adverse event.
Phase IIA Overall Survival	Date of on-study to the date of death from any cause or last follow-up	Among participants in the phase IIA cohort, median overall survival (OS) will be calculated from the on-study date using the Kaplan-Meier method, along with 95% confidence intervals on the median OS.OS is defined as the date of on-study to the date of death from any cause or last follow-up.
Phase IIA Progression-free Survival (PFS)	Time from the on-study date to documented evidence of disease progression	Among participants in the phase IIA cohort, median progression free survival (PFS) will be calculated from the on-study date using the Kaplan-Meier method, along with 95% confidence intervals on the median PFS. PFS is defined as the time from on-study date to documented evidence of disease progression. Disease progression was measured by the Response Evaluation Criteria in Solid Tumors (RECIST) and is defined as at least a 20% increase in the sum of the diameters of target lesions, taking as reference the smallest sum on study. And appearance of one or more new lesions.
Phase I - Number of Participants Who Experience a Clinical Response (Complete Response (CR)+Partial Response (PR)	Disease progression, a median of 43 days with range of 20 to 350 days.	The number of participants who experience a clinical response (Complete Response (CR)+Partial Response (PR) will be reported. Response was assessed by the Response Evaluation Criteria in Solid Tumors (RECIST). CR is disappearance of all target lesions; any pathological lymph nodes must have reduction in short axis to \<10 mm. PR is at least a 30% decrease in the sum of the diameters of target lesions, taking as reference the baseline sum of diameters.