Inclusion Criteria

        All Participants:

          -  Has relapsed or progressed following local standard treatments or for which no
             standard treatment is available.

          -  Consents to provide mandatory pre-treatment tumor tissue samples for the measurement
             of TROP2 and other biomarkers. There is no minimum TROP2 expression level required for
             inclusion.

          -  Consents to undergo mandatory on-treatment biopsy if clinically feasible and not
             contraindicated at the time of on-treatment biopsy, and consents to provide the tumor
             tissue samples from on-treatment biopsy for the measurement of TROP2 level and other
             biomarkers.

          -  Is aged ≥20 years old in Japan or ≥18 years old in other countries.

          -  Has an Eastern Cooperative Oncology Group performance status 0-1.

          -  Has a left ventricular ejection fraction (LVEF) ≥50% by either an ECHO or MUGA within
             28 days before enrollment.

          -  Has measurable disease based on RECIST version1.1.

          -  Has adequate bone marrow reserve and organ function within 7 days before Cycle 1, Day
             1.

          -  Has an adequate treatment washout period prior to Cycle 1, Day 1.

          -  If of reproductive/childbearing potential, agrees to use a highly effective from of
             contraception or avoid intercourse during and upon completion of the study and for at
             least 7 months for females and 4 months for males after the last dose of study drug,
             and agrees not to retrieve, freeze or donate sperm or ova starting at Screening and
             throughout the study period, and at least 7 months for males and 4 months for males
             after the final study drug administration.

          -  After being fully informed about their illness and the investigative nature of the
             protocol (including foreseeable risks and possible toxicities), is willing and able
             comply with the protocol and to provide written, ethics committee-approved informed
             consent form before performance of any study-specific procedures or examinations.

          -  Has a life expectancy of ≥3 months.

          -  Has no prior treatment with antibody drug conjugate with deruxtecan (including
             trastuzumab deruxtecan [T-DXd; DS-8201a] and patritumab deruxtecan [HER3-DXd; U31402])

          -  Has no prior treatment with trophoblast cell surface antigen 2 (TROP2)-targeted
             therapy

        NSCLC participants only:

          -  Has a pathologically documented unresectable advanced NSCLC disease not amenable to
             curative therapy

        TNBC participants only:

          -  Has a pathologically documented advanced/unresectable or metastatic breast cancer with
             HR- (estrogen and progesterone receptor) negative disease and HER2 negative expression
             according to the American Society of Clinical Oncology - College of American
             Pathologists guidelines (ASCO-CAP)

        HR positive, HER2-negative participants only:

          -  Pathologically documented unresectable or metastatic breast cancer that is:

               -  HER2-negative

               -  Positive for estrogen receptor and/or progesterone receptor

               -  Is documented refractory or resistant to endocrine therapy

               -  Was previously treated with a minimum of 1 and a maximum of 3 prior lines of
                  chemotherapy in the advanced/metastatic setting

        Small-cell lung cancer (SCLC) participants only:

          -  Pathologically documented unresectable or metastatic, and/or extensive-stage SCLC that
             was previously treated with 1 to 2 prior lines of therapy including platinum-based
             chemotherapy and immune checkpoint inhibitor

          -  No prior exposure to topotecan

        Endometrial cancer participants only:

          -  Pathologically documented recurrent or persistent endometrial cancer that relapsed or
             progressed after any established and/or curative therapies, including at least 1
             systemic therapy

        Pancreatic adenocarcinoma participants only:

          -  Pathologically documented unresectable or metastatic pancreatic cancer that was
             previously treated with at least 1 prior line of systemic therapy in neoadjuvant,
             adjuvant, locally advanced or metastatic setting

        HER2-negative gastric/GEJ cancer participants only:

          -  Pathologically documented unresectable or metastatic gastric/GEJ adenocarcinoma that
             was previously treated with at least 1 prior line of systemic therapy

          -  No known history of HER2-overexpression (Immunohistochemistry [IHC] 0, IHC 1 or IHC
             2+/ in situ hybridization [ISH]-negative) as classified by ASCO-CAP at any time

        Esophageal cancer participants only:

          -  Pathologically documented unresectable or metastatic esophageal cancer that:

               -  Is squamous or adenocarcinoma

               -  Was previously treated with at least 1 prior line of therapy including
                  platinum-based chemotherapy

        Head and neck squamous cell carcinoma (HNSCC) participants only:

          -  Pathologically documented unresectable or metastatic HNSCC that was previously treated
             with 1-3 prior lines of therapy including platinum and ICI (in combination or
             sequential), in the advanced or metastatic setting

        Transitional cell carcinoma of the urothelium participants only:

          -  Pathologically documented unresectable, locally advanced or metastatic, transitional
             cell carcinoma (transitional cell and mixed transitional/non-transitional cell
             histologies) of the urothelium (including renal pelvis, ureters, urinary bladder, and
             urethra) that was previously treated with at least 1 prior line of therapy including
             platinum-based chemotherapy and ICI (in combination or sequential).

          -  Was previously treated with enfortumab vedotin where available

        Colorectal cancer (CRC) participants only:

          -  Pathologically documented unresectable or metastatic CRC that was previously treated
             with, or were not considered candidates for, available therapies including
             fluoropyrimidine-based chemotherapy, an anti-vascular endothelial growth factor
             therapy, and an anti-epidermal growth factor (EGFR) therapy

          -  Has not progressed or relapsed within 6 months of therapy with irinotecan

        Platinum-resistant ovarian cancer participants only:

          -  Pathologically documented unresectable or metastatic ovarian cancer that:

               -  Is epithelial ovarian (including less-common histologies per National
                  Comprehensive Cancer Network (NCCN)

               -  Has relapsed or progressed within 6 months of platinum-based chemotherapy

        Platinum-sensitive ovarian cancer participants only:

          -  Pathologically documented unresectable or metastatic ovarian cancer that:

               -  Is epithelial ovarian (including less-common histologies per NCCN guidelines),
                  fallopian tube, or primary peritoneal presentation

               -  Has relapsed or progressed at least 6 months after the most recent platinum-based
                  chemotherapy

        Cervical cancer participants only:

          -  Pathologically documented unresectable or metastatic cervical cancer that relapsed or
             progressed after at least 1 prior line of systemic therapy

        Castration-resistant prostate cancer participants only:

          -  Pathologically documented unresectable or metastatic CRPC that:

               -  Is adenocarcinoma of the prostate without neuroendocrine differentiation or small
                  cell histology

               -  Is surgically or medically castrated, with testosterone levels of less than 50
                  nanograms per deciliter

               -  Objective progression by RECIST version 1.1 criteria for participants with
                  measurable disease after androgen deprivation

               -  Has relapsed or progressed after at least 1 of the following: abiraterone or
                  enzalutamide

               -  Has relapsed or progressed after at least 1, but not more than 2, cytotoxic
                  chemotherapy regimens for metastatic castration resistant prostate cancer
                  (mCRPC). At least 1 regimen must have contained a taxane. If a specific taxane
                  was used more than once, the regimens containing the same taxane would be
                  considered as 1 regimen in total.

        Exclusion Criteria:

          -  Has a history of malignancy, other than a tumor type specified in the Inclusion
             Criteria, except (a) adequately resected non-melanoma skin cancer, (b) curatively
             treated in situ disease, or (c) other solid tumors curatively treated, with no
             evidence of disease for ≥3 years.

          -  Has a history of myocardial infarction or unstable angina within 6 months before
             enrollment.

          -  Has a medical history of congestive heart failure (New York Heart Association classes
             II-IV) or a serious cardiac arrhythmia requiring treatment.

          -  Has a mean corrected QT interval (QTcF) prolongation to >470 ms based on average of
             the screening triplicate 12-lead ECGs.

          -  Has a history of non-infectious ILD/pneumonitis that required steroids, has current
             ILD/pneumonitis, or where suspected ILD/pneumonitis cannot be ruled out by imaging at
             screening.

          -  Has clinically significant corneal disease.

          -  Has an uncontrolled infection requiring IV antibiotics, antivirals, or antifungals.

          -  Has active human immunodeficiency virus infection that is uncontrolled (increasing
             plasma HIV RNA viral load) with medication, or has an active hepatitis B or C
             infection.

          -  Has spinal cord compression or clinically active brain metastases, defined as
             untreated and symptomatic, or requiring therapy with steroids or anticonvulsants to
             control associated symptoms. Participants with clinically inactive brain metastases
             may be included in the study. A minimum of 2 weeks must have elapsed between the end
             of whole brain radiotherapy and study enrollment. Participants with treated brain
             metastases that are no longer symptomatic and who require no treatment with steroids
             may be included in the study if they have recovered from the acute toxic effect of
             radiotherapy.

          -  Is lactating or pregnant as confirmed by pregnancy tests performed within 7 days
             before enrollment.

          -  Has unresolved toxicities from previous anticancer therapy.

          -  Has a concomitant medical condition that would increase the risk of toxicity, in the
             opinion of the Investigator.

          -  Has a history of severe hypersensitivity reactions to either the drug substances or
             inactive ingredients of DS-1062a.

          -  Has any other medical conditions, including cardiac disease or psychological
             disorders, and/or substance abuse that would increase the safety risk to the
             participant or interfere with participation of the participant or evaluation of the
             clinical study in the opinion of the Investigator.

          -  Clinically severe pulmonary compromise resulting from intercurrent pulmonary illnesses
             including, but not limited to, any underlying pulmonary disorder, or any autoimmune,
             connective tissue or inflammatory disorders with pulmonary involvement, or prior
             pneumonectomy.