A phase 2 multi-center investigation of efficacy of nab-sirolimus (formerly known as ABI-009 or nab-rapamycin) in patients with advanced malignant perivascular epithelioid cell tumor (PEComa).

This was a phase 2, single-arm, open-label, multi-center study to determine the efficacy and safety profile of nab-sirolimus in patients with advanced malignant PEComa. Patients were required to have measurable disease at baseline (per RECIST v1.1). Eligible patients received nab-sirolimus at 100 mg/m2 by IV infusion (over 30 minutes) weekly for 2 weeks followed by a week of rest (ie, on Day 1 and Day 8 in 21-day cycles). Patients remained on treatment until they experienced progressive disease or unacceptable toxicity, withdrew consent, or physician's decision. Patients who discontinued treatment entered the on-study Follow-up period for survival.

Computed tomography or magnetic resonance imaging (MRI) scans were performed at screening, every 6 weeks for the first year, then every 12 weeks thereafter until the end of treatment. Throughout treatment with nab-sirolimus, patients were routinely assessed for toxicities, the need for dose modifications, and response assessments.

The sample size was targeted to be ~30 patients in order to provide a reasonably precise estimate of the true ORR. Assuming an observed ORR of 30% and a sample size of 30, the lower bound of the 95% confidence interval (CI) for the estimated ORR would exclude values less than 14.7%.

The primary analysis was predefined to be conducted when all patients have had the opportunity to be treated for at least 6 months. The study remained open for 3 additional years and the final analysis occured at study closure.

Inclusion Criteria:

1. Patients must have a histologically confirmed diagnosis of malignant PEComa that is either metastatic or locally advanced and for which surgery is not a recommended option.

2. Patients must have available tumor block along with the corresponding pathology report (or approximately 30 unstained slides, with a minimum of 16 slides), and/or fresh biopsy to allow retrospective centralized confirmation of malignant PEComa and for mTOR pathway analysis and biomarker analysis.

3. Patients must have one or more measurable target lesions by CT scan or MRI. Measurable disease by RECIST v1.1.

4. Patients must not have been previously treated with an mTOR inhibitor.

5. Prior treatment (investigational or other), chemotherapy, radiotherapy, surgery, or other therapeutic agents (except mTOR inhibitors) is allowed, if completed after 5 half-lives or ≥28 days prior to enrollment, whichever is shorter.

6. Eligible patients, 18 years or older, with Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1.

7. Patients must have the following blood chemistry levels at screening (obtained

   ≤14 days prior to enrollment (local laboratory):

   1. total bilirubin ≤1.5 x upper limit of normal (ULN) mg/dl
   2. AST ≤2.5 x ULN (≤5 x ULN if attributable to liver metastases)
   3. serum creatinine ≤1.5 x ULN

8. Adequate biological parameters as demonstrated by the following blood counts at screening (obtained ≤14 days prior to enrollment, local laboratory):

   1. Absolute neutrophil count (ANC) ≥1.5 × 109/L;
   2. Platelet count ≥100,000/mm3 (100 × 109/L);
   3. Hemoglobin ≥9 g/dL.

9. Serum triglyceride <300 mg/dL; serum cholesterol < 350 mg/dL.

10. Male or non-pregnant and non-breast feeding female:

    • Females of child-bearing potential must agree to use effective contraception without interruption from 28 days prior to starting IP and while on study medication and have a negative serum pregnancy test (β -hCG) result at screening and agree to ongoing pregnancy testing during the course of the study, and after the end of study treatment.
    • Male patients must practice abstinence or agree to use a condom during sexual contact with a pregnant female or a female of childbearing potential while participating in the study, even if he has undergone a successful vasectomy.

11. Life expectancy of >3 months, as determined by the investigator.

12. Ability to understand and sign informed consent.

13. Willingness and ability to comply with scheduled visits, laboratory tests, and other study procedures.

Exclusion Criteria:

A patient will not be eligible for inclusion in this study if any of the following criteria apply:

1. Patients with lymphangioleiomyomatosis (LAM) are excluded.

2. Known active uncontrolled or symptomatic central nervous system (CNS) metastases. A patient with controlled and asymptomatic CNS metastases may participate in this study. As such, the patient must have completed any prior treatment for CNS metastases ≥28 days (including radiotherapy and/or surgery) prior to start of treatment in this study and should not be receiving chronic corticosteroid therapy for the CNS metastases.

3. Active gastrointestinal bleeding, if transfusion dependent.

4. Pre-existing thyroid abnormality is allowed provided thyroid function can be controlled with medication.

5. Uncontrolled serious medical or psychiatric illness. Patients with a "currently active" second malignancy other than non-melanoma skin cancers, carcinoma in situ of the cervix, resected incidental prostate cancer (staged pT2 with Gleason Score ≤ 6 and postoperative PSA <0.5 ng/mL), or other adequately treated carcinoma-in-situ are ineligible. Patients are not considered to have a "currently active" malignancy if they have completed therapy and are free of disease for ≥1 year).

6. Liver-directed therapy within 2 months of enrollment. Prior treatment with radiotherapy (including radio-labeled spheres and/or cyberknife, hepatic arterial embolization (with or without chemotherapy) or cyrotherapy/ablation) is allowed if these therapies did not affect the areas of measurable disease being used for this protocol.

7. Recent infection requiring systemic anti-infective treatment that was completed

   ≤14 days prior to enrollment (with the exception of uncomplicated urinary tract infection or upper respiratory tract infection).

8. Uncontrolled diabetes mellitus as defined by HbA1c >8% despite adequate therapy.

9. Unstable coronary artery disease or myocardial infarction during preceding 6 months.

10. Receiving any concomitant antitumor therapy.

11. Patients with history of interstitial lung disease and/or pneumonitis, or pulmonary hypertension.

12. The use of certain medications and illicit drugs within 5 half-lives or 28 days, whichever is shorter prior to the first dose of study drug and for the duration of the study will not be allowed.

13. Use of strong inhibitors and inducers of CYP3A4 within the 14 days prior to receiving the first dose of ABI-009. Additionally, use of any known CYP3A4 substrates with narrow therapeutic window (such as fentanyl, alfentanil, astemizole, cisapride, dihydroergotamine, pimozide, quinidine, terfanide) within the 14 days prior to receiving the first dose of ABI-009.

Safety Analysis Set: patients treated with nab-sirolimus (N = 34)

Safety and tolerability were monitored through continuous reporting of treatment-emergent and treatment-related adverse events (AEs) and serious AEs throughout the study, from the time the patient signed informed consent until 28 days after the last dose of study drug, up to 72 months.