PFS was defined as the time from randomization to progressive disease (based on blinded independent central radiologic review) or death, whichever occurred earlier. Tumor response was evaluated every 6 weeks during treatment by diagnostic anatomic imaging and objective response assessments were performed based on enhanced RECIST 1.1 criteria. According to enhanced RECIST 1.1, progressive disease was the appearance of one or more new lesions, OR an unambiguous increase in the sum of target lesion volumes with both 1) \>20% increase in the sum of volumes (SOV) of all target lesions (taking as reference the nadir) and 2) greater than two times the variability of the measurements estimated by the sponsor and/or its designees. PFS was analyzed for Part 2 participants only using the Kaplan-Meier method and median PFS was reported in weeks. Per protocol, Part 1 participants were not included in this analysis.

DLTs assessed during first 21-day cycle of Part 1 and defined as toxicities that met pre-defined severity criteria, were possibly, probably, or definitely related to triplet therapy, and could possibly result in a change in the given dose. Hematologic DLTs included Grade (Gr) 3 or Gr 4 neutropenia with fever \>38.5°C and/or infection requiring antibiotic or anti-fungal treatment, and any Gr 4-5 hematological toxicity EXCEPT Gr 4 anemia, leukopenia, lymphopenia, neutropenia lasting \<7 days, and thrombocytopenia lasting \<4 days, except if a platelet transfusion was required. Non-hematologic DLT defined as any Gr 3, 4, or 5 nonhematologic toxicity EXCEPT: Gr 3 nausea, vomiting, diarrhea, or dehydration judged by Investigator and SPONSOR to occur in setting of inadequate compliance with supportive care measures and last for less than 48 hours, alopecia of any grade, inadequately treated hypersensitivity reactions, or clinically non-significant, treatable or reversible lab abnormalities.

An AE was defined as any unfavorable and unintended change in the structure, function, or chemistry of the body temporally associated with the use of the SPONSOR's products, whether or not considered related to the use of the product. Any worsening (i.e., any clinically significant adverse change in frequency and/or intensity) of a preexisting condition which is temporally associated with the use of the SPONSOR's product was also an AE. The percentage of participants that experienced at least one AE was reported for each treatment arm.

An AE was defined as any unfavorable and unintended change in the structure, function, or chemistry of the body temporally associated with the use of the SPONSOR's products, whether or not considered related to the use of the product. Any worsening (i.e., any clinically significant adverse change in frequency and/or intensity) of a preexisting condition which is temporally associated with the use of the SPONSOR's product was also an AE. The percentage of participants that discontinued study treatment (paclitaxel, carboplatin, or MK-1775) due to an AE was reported for each treatment arm.