An Open-Label Study of the Safety, Tolerability, and Pharmacokinetic/Pharmacodynamic Profile of VX-803/M4344 as a Single Agent and in Combination With Cytotoxic Chemotherapy in Participants With Advanced Solid Tumors

Inclusion Criteria:

- Part A and A2: Participants with one histologically or cytologically confirmed
malignant advanced solid tumor, for which no standard therapy is available which may
convey clinical benefit

- Part B: Participants with one histologically or cytologically confirmed malignant
advanced solid tumor, for which no standard therapy is available which may convey
clinical benefit and/or participants must have progressed after at least 1 prior
chemotherapy regimen in the metastatic setting, and for which carboplatin (for Part
B1), gemcitabine (for Part B2), or cisplatin (for Part B3) would be considered
standard of care.

- Part C: Participants with advanced (locally advanced incurable or metastatic)
histologically or cytologically confirmed high-grade serous ovarian cancer (high
nuclear Grades 2 or 3). Participants should have either platinum-refractory (disease
progression during initial platinum therapy) or platinum-resistant (disease
progression <6 months after completion of platinum therapy) disease.

- Measurable disease according to RECIST criteria (Version 1.1)

- WHO performance status of 0 or 1

- Life expectancy of >=12 weeks

- Hematological and biochemical indices within acceptable ranges at Screening.

Exclusion Criteria:

- Radiotherapy, unless brief course for palliative therapy, endocrine therapy,
target-specific therapy, immunotherapy, or chemotherapy during the 4 weeks (6 weeks
for nitrosoureas and Mitomycin-C, and 4 weeks for investigational medicinal products)
or 4 drug half-lives before first dose of study drug, whichever is greater

- Part B: More than 6 cycles of prior therapy with carboplatin

- Parts B1, B3, and C: During prior platinum therapy, requirement for dose reduction or
discontinuation of carboplatin or cisplatin for toxicity or lack of tolerability

- Ongoing toxic manifestations of previous treatments. Exceptions to this are alopecia
or certain Grade 1 toxicities, which in the opinion of the investigator should not
exclude the participant

a. Any known history of Grade 4 thrombocytopenia with any prior chemotherapy regimen

- Spinal cord compression or brain metastases unless asymptomatic, treated, stable, and
not requiring steroids for at least 4 weeks before first dose of study drug

- Female participants who are already pregnant or lactating, or plan to become pregnant
within 6 months of the last dose of study drug are excluded. Female participants of
childbearing potential must adhere to contraception guidelines. Female participants
will be considered to be of nonchildbearing potential if they have undergone surgical
hysterectomy or bilateral oophorectomy or have been amenorrheic for over 2 years with
a screening serum follicle-stimulating hormone (FSH) level within the laboratory's
reference range for postmenopausal females.

- Male participants with partners of childbearing potential must agree to adhere to
contraception guidelines. Men with pregnant or lactating partners or partners who plan
to become pregnant during the study or within 6 months of the last dose of study drug
are excluded.

- Major surgery =<4 weeks before first dose of study drug or incomplete recovery from a
prior major surgical procedure

- Serious co-morbid medical conditions, including clinically-significant cardiac disease