Overview

This trial is a prospective, randomized (1:1 ratio), multicenter, comparative and phase II study, conducted in patients with unresectable advanced gastrointestinal stromal tumors (GIST) after failure of imatinib (disease progression),sunitinib and regorafenib (either disease progression or intolerance)

In the first arm, patients will be treated with imatinib + atezolizumab (experimental arm), whereas in the second arm, patients will be treated with imatinib alone (control arm).

The comparison between this two arms will allow to compare whether or not atezolizumab and imatinib is efficient for disease control, in terms of Progression-Free Survival improvement.

Eligibility

INCLUSION CRITERIA :

I1. Male or female ≥ 18 years at the day of consenting to the study;

        I2. Patients must have histologically confirmed diagnosis of GIST (within the French
        Reference Network in Pathology of Sarcomas - RRePS network); archival tumor sample must be
        made available for translational research program (in case there is no sufficient archival
        tumor material available, a biopsy must be performed prior to treatment start); Nota Bene:
        mutational status and level of expression of PD1/PD-L1 will not be considered as selection
        criteria but will be studied as endpoints for translational objectives.
        I3. Locally advanced or metastatic disease confirmed as measurable according to the RECIST
        V1.1 (Appendix 1);
        I4. Patients who previously failed to at least imatinib, sunitinib and then regorafenib.
        Failure is defined for Imatinib as progressive disease, and for sunitinib and regorafenib
        as progressive disease and/or intolerance;
        I5. Performance Status of the ECOG of 0 or 1;
        I6. Adequate bone marrow and organ function defined by the following laboratory results:
        a. Bone marrow: i. Hemoglobin ≥ 9.0 g/dl, ii. Absolute Neutrophils Count (ANC) ≥ 1.5 G/l,
        iii. Lymphocytes count ≥ 0.5 G/l, iv. Platelets ≥ 100 G/l;
        b. Coagulation: i. Prothrombin time ≤ 1.5 x Upper Limit of the Normal (ULN) for patients
        without therapeutic anticoagulation.
        Patients with therapeutic anticoagulation must have stable dose of treatment.
        c. Hepatic function: i. Total serum bilirubin ≤ 1.5 x ULN (except patients with Gilbert's
        syndrome who must have total serum bilirubin ≤ 3.0 x ULN), ii. Transaminases (ASAT/ALAT) ≤
        2.5 x ULN (or ≤ 5.0 x ULN in case of documented liver metastases) iii. Alkaline
        Phosphatases ≤ 2.5 x ULN (or ≤ 5.0 x ULN in case of documented bone metastases),
        d. Renal function: i. Serum creatinine ≤ 1.5 x ULN or Cr. Cl. ≥ 40ml/min/1.73m² (MDRD or
        CKD-EPI formula);
        I7. Willingness and ability to comply with the study requirements;
        I8. Signed and dated informed consent indicating that the patient has been informed of all
        the aspects of the trial prior to enrolment;
        I9. Women of childbearing potential are required to have a negative serum pregnancy test
        within 72 hours prior to study treatment start. A positive urine test must be confirmed by
        a serum pregnancy test;
        I10. Women of childbearing potential and male patients must agree to use adequate highly
        effective contraception for the duration of study participation (Appendix 3);
        I11. Patient must be covered by a medical insurance;
        EXCLUSION CRITERIA :
        E1. Prior malignancy within the last 3 years except for locally curable disease with no
        sign of relapse;
        E2. Patients in whom imatinib had been already reintroduced after sunitinib as second line;
        E3. Known D842V mutation in Exon 18 of PDGFRA;
        E4. Prior treatment with CD137 agonists or immune checkpoint blockade therapies, including
        anti-cytotoxic T lymphocyte-associated protein 4 , anti-TIGIT, anti PD-1,and anti PD-L1
        therapeutic antibodies;
        E5. Any approved anticancer therapy (chemotherapy, hormonal therapy or radiotherapy) or
        treatment with any investigational product within 2 weeks or within 5 elimination
        half-lives (whichever is longer) prior to study treatments start;
        E6. Residual adverse events from prior anticancer therapy that has not resolved to grade
        ≤1, except for alopecia and lab values (provided that inclusion criteria described in
        section 6.1 are met);
        E7. Symptomatic, untreated, or actively progressing central nervous system (CNS)
        metastases.
        Asymptomatic patients with treated CNS lesions are eligible, provided that all of the
        following criteria are met:
          -  Measurable disease, per RECIST v1.1, must be present outside the CNS.
          -  The patient has no history of intracranial hemorrhage or spinal cord hemorrhage.
          -  The patient has not undergone stereotactic radiotherapy within 7 days prior to
             randomization, whole-brain radiotherapy within 14 days prior to randomization, or
             neurosurgical resection within 28 days prior to randomization.
          -  The patient has no ongoing requirement for corticosteroids as therapy for CNS disease.
             Anticonvulsant therapy at a stable dose is permitted.
          -  Metastases are limited to the cerebellum or the supratentorial region (i.e., no
             metastases to the midbrain, pons, medulla, or spinal cord).
          -  There is no evidence of interim progression between completion of CNS-directed therapy
             and randomization.
          -  Spinal cord compression not definitively treated with surgery and/or radiation, and/or
             previously diagnosed and treated spinal cord compression without evidence that disease
             has been clinically stable for 2 weeks prior to screening.
          -  History of leptomeningeal disease.
        E8. Patients using or require to use while on the study of any prohibited concomitant
        and/or concurrent medications (see section "Prohibited concomitant/concurrent treatments) :
          -  Live, attenuated vaccines within 28 days prior to enrolment. Examples of live vaccines
             include, but are not limited to, the following: measles, mumps, rubella, chicken pox,
             yellow fever, rabies, BCG, and typhoid (oral) vaccine. Seasonal influenza vaccines for
             injection are generally killed virus vaccines and are allowed; however intranasal
             influenza vaccines (e.g. Flu-Mist®) are live attenuated vaccines, and are not allowed
             during the study active period.
          -  Treatment with systemic immunosuppressive medication (including, but not limited to,
             corticosteroids, cyclophosphamide, azathioprine, methotrexate, thalidomide, and
             anti-TNF-alpha agents) within 2 weeks prior to C1D1, or anticipation of need for
             systemic immunosuppressive medication during study treatment, with the following
             exceptions:
          -  Patients who receive acute, low-dose systemic immunosuppressant medication or a
             one-time pulse dose of systemic immunosuppressant medication (e.g., 48 hours of
             corticosteroids for a contrast allergy) are eligible for the study after Medical
             Monitor confirmation.
          -  Patients who receive mineralocorticoids (e.g., fludrocortisone), corticosteroids for
             chronic obstructive pulmonary disease or asthma, or low-dose corticosteroid.
          -  Systemic immunostimulatory agents (including, but not limited to, interferons and
             IL-2) are prohibited within 4 weeks or five half-lives of the drug (whichever is
             longer) prior to C1D1.
          -  Traditional herbal medicines since the ingredients of many herbal medicines are not
             fully studied and their use may result in unanticipated drug-drug interactions that
             may cause or confound assessment of toxicity,
        E9. Active or history of autoimmune disease or immune deficiency, including, but not
        limited to, myasthenia gravis, myositis, autoimmune hepatitis, systemic lupus
        erythematosus, rheumatoid arthritis, inflammatory bowel disease, antiphospholipid antibody
        syndrome, Wegener granulomatosis, Sjögren syndrome, Guillain-Barré syndrome, or multiple
        sclerosis (see Appendix 4 for a more comprehensive list of pre-existing autoimmune diseases
        and immune deficiencies), with the following exceptions:
          -  Patients with a history of autoimmune-related hypothyroidism who are on
             thyroid-replacement hormone are eligible for the study.
          -  Patients with controlled Type 1 diabetes mellitus who are on an insulin regimen are
             eligible for the study.
          -  Patients with eczema, psoriasis, lichen simplex chronicus, or vitiligo with
             dermatologic manifestations only (e.g., patients with psoriatic arthritis are
             excluded) are eligible for the study provided all of following conditions are met:
          -  Rash must cover less than 10% of body surface area
          -  Disease is well controlled at baseline and requires only low-potency topical
             corticosteroids
          -  No occurrence of acute exacerbations of the underlying condition requiring psoralen
             plus ultraviolet A radiation, methotrexate, retinoids, biologic agents, oral
             calcineurin inhibitors, or high-potency or oral corticosteroids within the previous 12
             months
        E10. History of severe allergic / anaphylactic reaction or other hypersensitivity reactions
        to:
          -  chimeric or humanized antibodies or fusion proteins,
          -  biopharmaceuticals produced in Chinese hamster ovary cells, any active substance or to
             any of the chemical excipients of atezolizumab (refer to its IB) or imatinib (refer to
             its respective SmPC)
        E11. Patients with active infectious disease:
          -  severe infections within 4 weeks prior to randomisation including but not limited to
             hospitalization for complications of infection, bacteraemia, or severe pneumonia,
          -  active infection requiring or have required treatment with therapeutic oral or IV
             antibiotics within 2 weeks prior to initiation of study treatment. Patients receiving
             prophylactic antibiotics (e.g., to prevent a urinary tract infection) are eligible for
             the study.
          -  active B or C hepatitis infection, Note: Patients with past Hepatitis B Virus (HBV)
             infection or resolved HBV infection (defined as having a negative HBsAg test and a
             positive antibody to hepatitis B core antigen [anti-HBc] antibody test) are eligible.
             Patients positive for Hepatitis C Virus (HCV) antibody are eligible only if polymerase
             chain reaction (PCR) is negative for HCV RNA.
          -  active tuberculosis
          -  HIV infection
        E12. Active or prior history of primary immunodeficiency;
        E13. Major surgical procedure within 28 days prior to study treatments start, or need for a
        major surgery during the course of the study;
        E14. Pregnancy or breastfeeding, or intention of becoming pregnant during study treatment
        or within :
          -  6 months after the final dose of study treatment for patients included in the standard
             arm (imatinib alone)
          -  11 months after the final dose of study treatment for patients included in the
             experimental arm (imatinib + atezolizumab) Women of childbearing potential must have a
             negative pregnancy test result within 72 hours prior to treatment start (any urine
             positive pregnancy test must be confirmed by a serum pregnancy test prior to treatment
             start);
        E15. Patient that impairs their ability to swallow and retain imatinib or with impairment
        of gastrointestinal (GI) function or GI disease that may significantly alter the absorption
        of imatinib (e.g., ulcerative diseases, uncontrolled nausea, vomiting, diarrhea,
        malabsorption syndrome, or small bowel resection)
        E16. Clinically significant unrelated systemic illness (e.g., significant cardiac,
        pulmonary, hepatic, or other organ dysfunction) that would compromise the patient's ability
        to tolerate study treatment or would likely interfere with study procedures or results.
        E17. Patients under tutorship or curatorship.