Inclusion criteria:

          -  Patients must have histologically or cytologically confirmed progressive advanced or
             metastatic solid tumor of one of the following:

               -  Platinum sensitive relapsed small cell lung cancer (module 1)

               -  gBRCAm HER2-negative metastatic breast cancer (module 2)

               -  gBRCAm ovarian cancer (modules 3 and 5)

               -  Metastatic or relapsed Gastric cancer (adenocarcinoma) (module 4)

               -  gBRCAm negative ovarian cancer (modules 6 and 7)

          -  At least one measurable lesion that can be accurately assessed at baseline by computed
             tomography (CT) (or magnetic resonance imaging [MRI] suitable for assessment as per
             RECIST 1.1. The baseline scan must be obtained within 28 days prior to the first dose
             of olaparib.

          -  Male or female patients, age ≥18 years (≥19 years for South Korea)

          -  Eastern Cooperative Oncology Group (ECOG) performance status 0-1

          -  Life expectancy ≥12 weeks

          -  Adequate organ and marrow function

          -  Ability to swallow oral medications (capsules and tablets) without chewing, breaking,
             crushing, opening or otherwise altering the product formulation. Patients should not
             have gastrointestinal illnesses that would preclude the absorption of olaparib, which
             is an oral agent. For the gastric cancer cohort, patients with a full or partial
             gastrectomy will be permitted.

          -  Ability of patient to understand and the willingness to sign a written informed
             consent document prior to any protocol related procedures, including screening
             evaluations.

          -  Female patients must either:

               -  Be of non-reproductive potential OR

               -  Have a negative serum pregnancy test within 28 days of study treatment and
                  confirmed prior to treatment on Day 1, and agree to use contraception if they or
                  their partner are of reproductive potential

        Exclusion criteria

          -  Prior chemotherapy or other systemic anticancer therapy within 4 weeks prior to start
             of olaparib treatment, 6 weeks for nitrosoureas or mitomycin. Exceptions include:
             Anti-hormonal treatment for ER positive or PR positive breast cancer is allowed until
             7 days prior to treatment with olaparib, exposure to an investigational agent within
             30 days or 5 half-lives (whichever is the longer) prior to start of olaparib treatment
             is not allowed, prior receipt of biologics targeting T cell co-regulatory proteins
             and/or immune checkpoints is not allowed. Examples include MEDI4736 or other PD1 or
             PD-L1 or PD-L2 inhibitors or anti-CTLA4 therapy, previous treatment with a PARP
             inhibitor, is not allowed.

          -  Radiation therapy within 4 weeks prior to start of olaparib treatment (includes
             radiation targeting bone metastases) or radionuclide treatment within 6 weeks of
             treatment start.

          -  Current dependency on total parenteral nutrition or IV fluid hydration.

          -  Concomitant use of known strong cytochrome P450 (CYP) 3A (CYP3A) inhibitors or
             moderate CYP3A inhibitors. Concomitant use of known strong or moderate CYP3A inducers.

          -  Concomitant therapy with any other anticancer therapy or chronic use of systemic
             corticosteroids.

          -  Previous allogenic bone marrow transplant or double umbilical cord blood
             transplantation

          -  Whole blood transfusions in the last 120 days

          -  Patients with symptomatic or uncontrolled brain metastases.

          -  Patients being considered at poor medical risk due to a serious, uncontrolled medical
             disorder or non-malignant systemic disease.

          -  Any psychiatric disorder that prohibits obtaining informed consent

          -  Major surgery or significant traumatic injury within 2 weeks of run-in

          -  Immunocompromised patients

          -  QTc prolongation >470 msec or other significant ECG abnormality noted within 14 days
             of treatment

          -  Pregnant and breastfeeding women are excluded.

          -  Involvement in the planning and/or conduct of the study (applies to both AstraZeneca
             staff and/or staff at the study site)

          -  Previous enrolment in the present study

          -  Participation in a clinical study within 28 days or 5 half-lives of the drug,
             whichever is longer.