All participants in Phase 1 Part 1A (Dose Escalation) who received at least 1 dose of XTX202 and experienced a DLT. DLTs were defined as the following:

• Any treatment-related Grade ≥ 3 toxicity

• Any Grade febrile neutropenia

• The following nonhematologic exceptions:

  • Grade 3 nausea or vomiting lasting < 3 days
  • Grade 3 fatigue lasting < 7 days

• Any treatment-related toxicity that resulted in a treatment delay of ≥ 7 days

Treatment-emergent adverse event (TEAE) is defined as any adverse event that starts or increases in severity on or after the first dose of study drug and no later than 90 days after the last dose of study drug. Adverse events are graded using the NCI CTCAE version 5.0.

All participants who received XTX202 in Phase 1 Part 1A and Part 1B.

Percentage of participants who achieved at least one confirmed Complete Response (CR) or Partial Response (PR). Response is based on Investigator assessment according to RECIST v1.1.

In the analysis set used for ORR, participants are assigned to a treatment group based on the initial dose received. In the Participant Flow module, participants are assigned to a treatment group based on the highest dose received. One participant in Phase 2 Part 2B initially received XTX202 1.4 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group.

All participants in Phase 2 Part 2A and Part 2B with measurable disease at baseline who received XTX202 and had at least 1 post-Baseline response assessment or discontinued treatment due to disease progression (including death caused by disease progression) prior to the first efficacy evaluation were included in the analysis set.

Number of participants that experienced a clinical laboratory test abnormality. Abnormalities considered are those Grade 3-4 events with a >= 1 grade increase from baseline. Baseline is defined as the last available measurement taken prior to the first administration of study treatment. Laboratory data is graded using the NCI CTCAE version 5.0. Participants are included only once, in the highest level of CTCAE Grade.

All participants who received XTX202 in Phase 1 Part 1A and Part 1B with both baseline and at least one post-baseline result.

Number of participants that experienced a clinical laboratory test abnormality. Abnormalities considered are those Grade 3-4 events with a >= 1 grade increase from baseline. Baseline is defined as the last available measurement taken prior to the first administration of study treatment. Laboratory data is graded using the NCI CTCAE version 5.0. Participants are included only once, in the highest level of CTCAE Grade.

All participants who received XTX202 in Phase 1 Part 1A and Part 1B with both baseline and at least one post-baseline result.

Number of participants with shift from baseline in laboratory results. Baseline is defined as the last available measurement taken prior to the first administration of study treatment. Participants with both baseline and at least one postbaseline result are included. Participants are included only once, in the highest level of CTCAE Grade. Missing = number of patients with missing baseline and/or post baseline laboratory value.

All participants who received XTX202 in Phase 1 Part 1A and Part 1B with both baseline and at least one post-baseline result.

Number of participants with shift from baseline in laboratory results. Baseline is defined as the last available measurement taken prior to the first administration of study treatment. Participants with both baseline and at least one postbaseline result are included. Participants are included only once, in the highest level of CTCAE Grade. Missing = number of patients with missing baseline and/or post baseline laboratory value. Missing = number of patients with missing baseline and/or post baseline laboratory value

All participants who received XTX202 in Phase 1 Part 1A and Part 1B with both baseline and at least one post-baseline result.

Percentage of participants who achieved at least one confirmed Complete Response (CR) or Partial Response (PR). Response will be based on Investigator's assessment according to RECIST v1.1.

All subjects in Phase 1 Part 1A and Part 1B with measurable disease at baseline who received XTX202 and had at least 1 post-Baseline response assessment or discontinued treatment due to disease progression (including death caused by disease progression) prior to the first efficacy evaluation.

Duration of response is defined as time from first documentation of a subsequently confirmed objective response (CR or PR) to the date of the first documentation of radiographic disease progression according to Investigator assessment by RECIST v1.1, or death due to any cause, whichever occurs first. Participants who do not have an observed documented disease progression or death from any cause will be censored at the latest tumor response assessment date.

All participants in Phase 2 Part 2A and Part 2B with measurable disease at baseline who received XTX202 and had at least 1 post-Baseline response assessment or discontinued treatment due to disease progression (including death caused by disease progression) prior to the first efficacy evaluation and had a confirmed objective response (CR or PR).

Disease Control Rate (DCR) is defined as percentage of participants with confirmed BOR of CR, PR or SD (minimum duration of 6 weeks) according to RECIST v1.1, after the first dose of study treatment.

In the analysis set used for DCR, participants are assigned to a treatment group based on the initial dose received. In the Participant Flow module, participants are assigned to a treatment group based on the highest dose received. One participant in Phase 2 Part 2B initially received XTX202 1.4 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group.

All participants in Phase 2 Part 2A and Part 2B with measurable disease at baseline who received XTX202 and had at least 1 post-Baseline response assessment or discontinued treatment due to disease progression (including death caused by disease progression) prior to the first efficacy evaluation were included in the analysis set.

OS is defined as the time from first administration of study treatment to death due to any cause. For participants without a record of death, OS will be censored at the date they were last known alive.

In the analysis set used for OS, participants are assigned to a treatment group based on the initial dose received.. In the Participant Flow module, participants are assigned to a treatment group based on the highest dose received. One participant in Phase 2 Part 2B initially received XTX202 1.4 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group

All participants who received XTX202 in Phase 2 Part 2A and Part 2B were included in the analysis set

PFS is defined as the time from first administration of study treatment until first documentation of radiographic PD according to RECIST v1.1, or death due to any cause, whichever occurs first. Participants who do not have an observed documented disease progression or death from any cause will be censored at the latest tumor response assessment date.

In the analysis set used for PFS, participants are assigned to a treatment group based on the initial dose received. In the Participant Flow module, participants are assigned to a treatment group based on the highest dose received. One participant in Phase 2 Part 2B initially received XTX202 1.4 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group

All participants who received XTX202 in Phase 2 Part 2A and Part 2B were included in the analysis set.

Treatment-emergent adverse event is defined as any adverse event (AE) that starts or increases in severity on or after the first dose of study drug and no later than 90 days after the last dose of study drug. AEs are graded using the NCI CTCAE version 5.0.

All participants who received XTX202 in Phase 2 Part 2A and Part 2B.

Number of participants that experienced a clinical laboratory test abnormality. Abnormalities considered are those Grade 3-4 events with a >= 1 grade increase from baseline. Baseline is defined as the last available measurement taken prior to the first administration of study treatment. Laboratory data is graded using the NCI CTCAE version 5.0. Participants are included only once, in the highest level of CTCAE Grade.

All participants who received XTX202 in Phase 2 Part 2A and Part 2B with both baseline and at least one post-baseline result.

Number of participants that experienced a clinical laboratory test abnormality. Abnormalities considered are those Grade 3-4 events with a >= 1 grade increase from baseline. Baseline is defined as the last available measurement taken prior to the first administration of study treatment. Laboratory data is graded using the NCI CTCAE version 5.0. Participants are included only once, in the highest level of CTCAE Grade.

All participants who received XTX202 in Phase 2 Part 2A and Part 2B with both baseline and at least one post-baseline result.

Number of participants with shift from baseline in laboratory results. Baseline is defined as the last available measurement taken prior to the first administration of study treatment. Participants with both baseline and at least one postbaseline result are included. Participants are included only once, in the highest level of CTCAE Grade. Missing = number of patients with missing baseline and/or post baseline laboratory value.

All participants who received XTX202 in Phase 2 Part 2A and Part 2B with both baseline and at least one post-baseline result.

Number of participants with shift from baseline in laboratory results. Baseline is defined as the last available measurement taken prior to the first administration of study treatment. Participants with both baseline and at least one postbaseline result are included. Participants are included only once, in the highest level of CTCAE Grade. Missing = number of patients with missing baseline and/or post baseline laboratory value.

All participants who received XTX202 in Phase 2 Part 2A and Part 2B with both baseline and at least one post-baseline result.

Plasma Concentration of Total XTX202 by Nominal Time (h) From End of Infusion Following a Single IV Administration of XTX202.

In the analysis set used for PK, participants are assigned to a treatment group based on the initial dose received.

In the Participant Flow module, participants are assigned to a treatment group based on the highest dose received. One participant in Phase 2 Part 2B initially received XTX202 1.4 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group. One participant in Phase 1 Part 1B initially received XTX202 2.8 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group.

Participants received at least one dose of XTX202 and had at least 1 post dose measurement of XTX202 without protocol deviations or events affecting the validity of the PK results.

Plasma Concentration of Intact XTX202 by Nominal Time (h) From End of Infusion Following a Single IV Administration of XTX202.

In the analysis set used for PK, participants are assigned to a treatment group based on the initial dose received.

In the Participant Flow module, participants are assigned to a treatment group based on the highest dose received. One participant in Phase 2 Part 2B initially received XTX202 1.4 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group. One participant in Phase 1 Part 1B initially received XTX202 2.8 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group.

Participants received at least one dose of XTX202 and had at least 1 post dose measurement of XTX202 without protocol deviations or events affecting the validity of the PK results.

Plasma Trough Concentration of Total XTX202 Following Multiple IV Administrations of XTX202.

In the analysis set used for PK, participants are assigned to a treatment group based on the initial dose received.

In the Participant Flow module, participants are assigned to a treatment group based on the highest dose received. One participant in Phase 2 Part 2B initially received XTX202 1.4 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group. One participant in Phase 1 Part 1B initially received XTX202 2.8 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group

Participants received at least one dose of XTX202 and had at least 1 post dose measurement of XTX202 without protocol deviations or events affecting the validity of the PK results.

Plasma Trough Concentration of Intact XTX202 Following Multiple IV Administrations of XTX202.

In the analysis set used for PK, participants are assigned to a treatment group based on the initial dose received.

In the Participant Flow module, participants are assigned to a treatment group based on the highest dose received. One participant in Phase 2 Part 2B initially received XTX202 1.4 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group. One participant in Phase 1 Part 1B initially received XTX202 2.8 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group.

Participants received at least one dose of XTX202 and had at least 1 post dose measurement of XTX202 without protocol deviations or events affecting the validity of the PK results.

Cmax following a single IV infusion of XTX202.

In the analysis set used for PK, participants are assigned to a treatment group based on the initial dose received.

In the Participant Flow module, participants are assigned to a treatment group based on the highest dose received. One participant in Phase 2 Part 2B initially received XTX202 1.4 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group. One participant in Phase 1 Part 1B initially received XTX202 2.8 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group.

Participants received at least one dose of XTX202 and had at least 1 post dose measurement of XTX202 without protocol deviations or events affecting the validity of the PK results.

Cmax following a single IV infusion of XTX202.

In the analysis set used for PK, participants are assigned to a treatment group based on the initial dose received.

In the Participant Flow module, participants are assigned to a treatment group based on the highest dose received. One participant in Phase 2 Part 2B initially received XTX202 1.4 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group. One participant in Phase 1 Part 1B initially received XTX202 2.8 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group.

Participants received at least one dose of XTX202 and had at least 1 post dose measurement of XTX202 without protocol deviations or events affecting the validity of the PK results.

Time of maximum observed concentration (Tmax) of total XTX202 following a single IV infusion of XTX202.

In the analysis set used for PK, participants are assigned to a treatment group based on the initial dose received.

In the Participant Flow module, participants are assigned to a treatment group based on the highest dose received. One participant in Phase 2 Part 2B initially received XTX202 1.4 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group. One participant in Phase 1 Part 1B initially received XTX202 2.8 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group.

Participants received at least one dose of XTX202 and had at least 1 post dose measurement of XTX202 without protocol deviations or events affecting the validity of the PK results. Note: In Phase 1 Part 1A, Dose Escalation- XTX202 0.53 mg/kg Arm, Tmax value for Cycle 1 was reported based on measured concentration at collection timepoint scheduled immediately prior to Cycle 2 dose, however this collection timepoint may have been taken following the second dose

Time of maximum observed concentration (Tmax) of intact XTX202 following a single IV infusion of XTX202.

In the analysis set used for PK, participants are assigned to a treatment group based on the initial dose received.

In the Participant Flow module, participants are assigned to a treatment group based on the highest dose received. One participant in Phase 2 Part 2B initially received XTX202 1.4 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group. One participant in Phase 1 Part 1B initially received XTX202 2.8 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group.

Participants received at least one dose of XTX202 and had at least 1 post dose measurement of XTX202 without protocol deviations or events affecting the validity of the PK results. Note: In Phase 1 Part 1A, Dose Escalation- XTX202 0.53 mg/kg Arm, Tmax value for Cycle 1 was reported based on measured concentration at collection timepoint scheduled immediately prior to Cycle 2 dose, however this collection timepoint may have been taken following the second dose.

Area under the curve (AUC)of total XTX202 following a single IV infusion of XTX202.

In the analysis set used for PK, participants are assigned to a treatment group based on the initial dose received.

In the Participant Flow module, participants are assigned to a treatment group based on the highest dose received. One participant in Phase 2 Part 2B initially received XTX202 1.4 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group. One participant in Phase 1 Part 1B initially received XTX202 2.8 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group.

Participants received at least one dose of XTX202 and had at least 1 post dose measurement of XTX202 without protocol deviations or events affecting the validity of the PK results

Area under the curve (AUC) of intact XTX202 following a single IV infusion of XTX202.

In the analysis set used for PK, participants are assigned to a treatment group based on the initial dose received.

In the Participant Flow module, participants are assigned to a treatment group based on the highest dose received. One participant in Phase 2 Part 2B initially received XTX202 1.4 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group. One participant in Phase 1 Part 1B initially received XTX202 2.8 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group.

Participants received at least one dose of XTX202 and had at least 1 post dose measurement of XTX202 without protocol deviations or events affecting the validity of the PK results

Half-life (T1/2) of total XTX202 following a single IV infusion of XTX202.

In the analysis set used for PK, participants are assigned to a treatment group based on the initial dose received.

In the Participant Flow module, participants are assigned to a treatment group based on the highest dose received. One participant in Phase 2 Part 2B initially received XTX202 1.4 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group. One participant in Phase 1 Part 1B initially received XTX202 2.8 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group.

Participants received at least one dose of XTX202 and had at least 1 post dose measurement of XTX202 without protocol deviations or events affecting the validity of the PK results

Half-life (T1/2) of intact XTX202 following a single IV infusion of XTX202.

In the analysis set used for PK, participants are assigned to a treatment group based on the initial dose received.

In the Participant Flow module, participants are assigned to a treatment group based on the highest dose received. One participant in Phase 2 Part 2B initially received XTX202 1.4 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group. One participant in Phase 1 Part 1B initially received XTX202 2.8 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group.

Participants received at least one dose of XTX202 and had at least 1 post dose measurement of XTX202 without protocol deviations or events affecting the validity of the PK results

Systemic clearance (CL) of Total XTX202 following a single IV infusion of XTX202.

In the analysis set used for PK, participants are assigned to a treatment group based on the initial dose received.

In the Participant Flow module, participants are assigned to a treatment group based on the highest dose received. One participant in Phase 2 Part 2B initially received XTX202 1.4 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group. One participant in Phase 1 Part 1B initially received XTX202 2.8 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group.

Participants received at least one dose of XTX202 and had at least 1 post dose measurement of XTX202 without protocol deviations or events affecting the validity of the PK results.

Systemic clearance (CL) of intact XTX202 following a single IV infusion of XTX202.

In the analysis set used for PK, participants are assigned to a treatment group based on the initial dose received.

In the Participant Flow module, participants are assigned to a treatment group based on the highest dose received. One participant in Phase 2 Part 2B initially received XTX202 1.4 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group. One participant in Phase 1 Part 1B initially received XTX202 2.8 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group.

Participants received at least one dose of XTX202 and had at least 1 post dose measurement of XTX202 without protocol deviations or events affecting the validity of the PK results.

Volume of distribution (Vd) of total XTX202 following a single IV infusion of XTX202.

In the analysis set used for PK, participants are assigned to a treatment group based on the initial dose received.

In the Participant Flow module, participants are assigned to a treatment group based on the highest dose received. One participant in Phase 2 Part 2B initially received XTX202 1.4 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group. One participant in Phase 1 Part 1B initially received XTX202 2.8 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group.

Participants received at least one dose of XTX202 and had at least 1 post dose measurement of XTX202 without protocol deviations or events affecting the validity of the PK results.

Volume of distribution (Vd) of intact XTX202 following a single IV infusion of XTX202.

In the analysis set used for PK, participants are assigned to a treatment group based on the initial dose received.

In the Participant Flow module, participants are assigned to a treatment group based on the highest dose received. One participant in Phase 2 Part 2B initially received XTX202 1.4 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group. One participant in Phase 1 Part 1B initially received XTX202 2.8 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group.

Participants received at least one dose of XTX202 and had at least 1 post dose measurement of XTX202 without protocol deviations or events affecting the validity of the PK results.

Overall ADA Incidence Following a Single IV Administration of XTX202

In the analysis set used for ADA, participants are assigned to a treatment group based on the initial dose received.

In the Participant Flow module, participants are assigned to a treatment group based on the highest dose received. One participant in Phase 1 Part 1B initially received XTX202 2.8 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group.

Participants who received at least one dose of XTX202 and had at least one post baseline blood sample collected to assess immunogenicity with reportable result.

Overall ADA Incidence Following a Single IV Administration of XTX202.

In the analysis set used for ADA, participants are assigned to a treatment group based on the initial dose received.

In the Participant Flow module, participants are assigned to a treatment group based on the highest dose received. One participant in Phase 2 Part 2B initially received XTX202 1.4 mg/kg, then increased the dose to 4.0 mg/kg at a later cycle and was therefore included in the XTX202 4.0 mg/kg dose group.

Participants who received at least one dose of XTX202 and had at least one post baseline blood sample collected to assess immunogenicity with reportable result.