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Pembrolizumab and Reirradiation in Bevacizumab Naïve and Bevacizumab Resistant Recurrent Glioblastoma

Phase II Trial of Pembrolizumab and Reirradiation in Bevacizumab Naïve and Bevacizumab Resistant Recurrent Glioblastoma

Status
Completed
Phases
Phase 2
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT03661723
Enrollment
60
Registered
2018-09-07
Start date
2018-09-28
Completion date
2024-08-01
Last updated
2024-09-19

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Glioblastoma

Keywords

Glioblastoma

Brief summary

This research study is studying pembrolizumab and re-irradiation as possible treatments for glioblastoma. The drugs involved in this study are: * Pembrolizumab * Radiation * Bevacizumab, an FDA-approved drug for treating recurrent glioblastoma multiforme (GBM)

Detailed description

This research study is a Phase II clinical trial. Phase II clinical trials test the safety and effectiveness of an investigational intervention to learn whether the intervention works in treating a specific disease. Investigational means that the intervention is being studied. How the Study Interventions work: Pembrolizumab: Pembrolizumab has been studied in lab experiments and in other types of cancer, and information from these studies suggests that it may be beneficial in this type of cancer. Pembrolizumab is a drug (an antibody) that may treat cancer by working with the immune system. The FDA (the U.S. Food and Drug Administration) has not approved pembrolizumab for this specific disease but it has been approved for other uses. Radiation (Re-irradiation): Radiotherapy destroys cancer cells using radiation aimed at a cancer from a machine. The FDA (the U.S. Food and Drug Administration) has approved re-irradiation as a treatment option for this disease. Bevacizumab: Bevacizumab (also known as Avastin) is designed to prevent or slow down the growth of cancer cells by blocking the growth of blood vessels. The FDA (the U.S. Food and Drug Administration) has approved bevacizumab as a treatment option for this disease. In this research study, the investigators are looking to determine if this combination (pembrolizumab + re-irradiation) proves helpful in treating this cancer. If the participant has already been receiving bevacizumab, the participant will continue to receive this along with pembrolizumab and re-irradiation. By doing this, the investigators will look to determine if this combination (pembrolizumab and bevacizumab + re-irradiation) proves helpful in treating this cancer. This study will also test the safety and tolerability of this combination (pembrolizumab + re-irradiation) when given alone or with bevacizumab

Interventions

DRUGPembrolizumab

Pembrolizumab is a drug (an antibody) that may treat cancer by working with the immune system

DRUGBevacizumab

Bevacizumab (also known as Avastin) is designed to prevent or slow down the growth of cancer cells by blocking the growth of blood vessels.

Radiotherapy destroys cancer cells using radiation aimed at a cancer from a machine

Sponsors

Merck Sharp & Dohme LLC
CollaboratorINDUSTRY
Dana-Farber Cancer Institute
Lead SponsorOTHER

Study design

Allocation
NON_RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
NONE

Eligibility

Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No

Inclusion criteria

1.1 Histologically confirmed World Health Organization (WHO) Grade IV glioblastoma. Patients with original histology of low-grade glioma and subsequent histological diagnosis of GBM are eligible. Other WHO grade IV glial neoplasms such as gliosarcoma are NOT eligible 1.2 Willing and able to provide written informed consent/assent for the trial 1.3 ≥ 18 years of age on day of signing informed consent 1.4 Karnofsky performance status (KPS) ≥ 70 (Appendix A) 1.5 Unequivocal evidence for tumor progression by MRI scan 1.6 MRI within 14 days prior to start of study therapy (with vascular imaging when possible). Corticosteroid dose must be stable or decreasing for at least 5 days prior to the scan. If steroids are added or the steroid dose is increased between the date of the screening MRI scan and Day 1 dose, a new baseline scan is required 1.7 Measurable disease as per Response Assessment in Neuro-Oncology (RANO) criteria 1.8 Cohort A patients must be at their first or second relapse; Cohort B patients must have progressed on no more than one prior bevacizumab-containing regimen (may have received any # of non-bevacizumab-containing regimens). Patients who were treated with prior bevacizumab but did not progress or experienced significant toxicity, are not eligible 1.9 Previous first line therapy with at least radiotherapy utilizing standard dosing of CNS radiation - for either high-grade or low-grade glial neoplasm 1.10 The following time periods must have elapsed from projected Day 1 dose: 1. At least 3 weeks from prior surgical resection 2. At least 1 week from stereotactic biopsy 3. At least 6 months from completion of prior radiotherapy (patient may still be eligible if s/he has a new area of enhancement outside the 80% isodose line of the original radiation field) 4. At least 4 weeks from cytotoxic therapy (at least 23 days for temozolomide, and at least 6 weeks from nitrosoureas) 5. At least 1 week from cancer vaccines 6. At least 6 weeks from antibodies 7. At least 4 weeks (or 5 half-lives, whichever is shorter) from other anti-tumor therapies (not including tumor treating fields or cancer vaccines); at least 1 week from NovoTTF (Optune) or other tumor treating fields and cancer vaccines 8. Cohort B patients only: Day 1 of bevacizumab on-study must be at least 3 weeks from last dose of prior course of Avastin/bevacizumab. 1.11 All clinically significant toxic effects of prior therapy must have recovered to grade 0 or 1 or pre-treatment baseline (excluding alopecia, laboratory values listed per inclusion criteria, and lymphopenia) 1.12 Adequate organ function as defined below (screening labs performed within 14 days of treatment initiation): 1.12.1 Hematologic: Absolute neutrophil count (ANC) ≥1,500 /uL; Platelets ≥100,000 / uL; Hemoglobin ≥9 g/dL or ≥5.6 mmol/L 1.12.2 Renal: Serum creatinine ≤1.5 X institutional upper limit of normal (ULN) OR Measured or calculated creatinine clearance (GFR can also be used in place of creatinine or CrCl) ≥60 mL/min for participant with creatinine levels \> 1.5 X institutional ULN 1.12.3 Hepatic Serum total bilirubin ≤ 1.5 X institutional ULN OR Direct bilirubin ≤ institutional ULN for participants with total bilirubin levels \> 1.5 X institutional ULN; aspartate aminotransferase (AST; SGOT) and alanine aminotransferase (ALT; SGPT) ≤ 2.5 X institutional ULN (OR ≤ 5 X institutional ULN for participants with Gilberts syndrome) 1.12.4 Coagulation: International Normalized Ratio (INR) or Prothrombin Time (PT) Activated Partial Thromboplastin Time (aPTT) ≤1.5 X institutional ULN unless participant is receiving anticoagulant therapy as long as PT or aPTT is within therapeutic range of intended use of anticoagulants 1.12.5 Pulmonary: Resting baseline oxygen saturation by pulse oximetry ≥92% at rest 1.13 Negative urine or serum pregnancy within 72 hours prior to registration from any woman of child-bearing potential (WOCBP), defined as any woman physiologically capable of becoming pregnant. If the urine test is positive or cannot be confirmed as negative, a serum pregnancy test will be required. 1.14 WOCBP (defined above) must agree to use a highly effective method of contraception (detailed in protocol eligibility) consistently and correctly as described below during study treatment and for 120 days after study discontinuation. 1.15 Male participants must agree to use at least one of the methods of contraception detailed in protocol eligibility starting with the first dose of study therapy through 120 days after the last dose of therapy.

Exclusion criteria

2.1 Recurrent tumor greater than 6 cm in maximum diameter 2.2 Currently participating or plans to participate in another study of an investigational agent or using an investigational device. 2.3 Tumor primarily localized to the brainstem or spinal cord. 2.4 Presence of multifocal tumor, diffuse leptomeningeal or extracranial disease. NOTE: Not all instances of multifocal disease will exclude a potential patient; only patients with multifocal sites of active disease will be excluded. (e.g. A patient with a previously treated lesion that remains stable would not be excluded.) Medical History/Conditions/Concomitant Medical Illnesses: 2.5 Diagnosis of immunodeficiency. 2.6 History or current evidence of any condition, therapy, or laboratory abnormality that might confound the results of the trial, interfere with the participant's participation for the full duration of the trial, or is not in the best interest of the participant to participate, in the opinion of the treating investigator. e.g. unstable angina pectoris, cardiac arrhythmia or psychiatric illness/social situations that would limit compliance with study requirements. 2.7 History of known coagulopathy that increases risk of bleeding or a history of clinically significant hemorrhage within 12 months of start of study drug. 2.8 Evidence of intratumoral or peritumoral hemorrhage on baseline MRI scan other than those that are grade ≤ 1 and either post-operative or stable on at least 2 consecutive MRI scans. 2.9 Gastrointestinal bleeding or any other hemorrhage/bleeding event CTCAE Grade \> 3 within 6 months of start of study drug. 2.10 Known additional malignancy that is progressing or requires active treatment within 1 year of start of study drug, except for those treated with surgical therapy only (e.g. basal cell carcinoma of the skin, squamous cell carcinoma of the skin, or in situ cervical cancer that has undergone potentially curative therapy). 2.11 Active autoimmune disease requiring systemic treatment in the past 2 years (e.g. with use of disease modifying agents, corticosteroids or immunosuppressive drugs). Replacement therapy (eg thyroxine, insulin, or physiologic corticosteroid replacement for adrenal insufficiency or pituitary/hypothalamic dysfunction, etc.) is not considered a form of systemic treatment. 2.12 History of (non-infectious) pneumonitis that required steroids or has current pneumonitis. 2.13 Active infection requiring systemic therapy. 2.14 Known psychiatric or substance abuse disorders that would interfere with cooperation with the requirements of the trial. 2.15 Known history of Human Immunodeficiency Virus (HIV) (HIV 1/2 antibodies) and is receiving antiretroviral therapy. 2.16 Known active Hepatitis B (e.g., HBsAg reactive) or Hepatitis C \[e.g., hepatitis C virus (HCV) RNA (qualitative) is detected\]. 2.17 History of non-healing wounds or ulcers, or bone refractures within 3 months of fracture. 2.18 History of arterial thromboembolism within 12 months of start of study drug. 2.19 Clinically significant cardiovascular disease within 12 months of start of study drug, including myocardial infarction, unstable angina, grade 2 or greater peripheral vascular disease, cerebrovascular accident, transient ischemic attack, congestive heart failure, or arrhythmias not controlled by outpatient medication, percutaneous transluminal coronary angioplasty/stent. 2.20 Known history of active Bacillus Tuberculosis (TB) 2.21 Known hypersensitivity to any of the study therapy products and/or any of their excipients. 2.22 Is pregnant or breastfeeding, or expecting to conceive within the projected duration of the trial, starting with the screening visit through 120 days after the last dose of trial treatment. Prior Therapy: 2.23 Has received prior interstitial brachytherapy, implanted chemotherapy, stereotactic radiosurgery or therapeutics delivered by local injection or convection enhanced delivery (this exclusion applies to any locally administered therapy, including intratumoral vaccines). 2.24 Has received prior therapy with an anti-PD-1, anti-PD-L1, or anti-PD-L2 or with an agent directed to another stimulatory or co-stimulatory T-cell receptor (eg CTLA-4, OX-40, CD137). (These therapies target checkpoint proteins on immune cells called T-Cells.PD-1 = Programmed cell death protein 1. CTLA-4 = cytotoxic T-lymphocyte-associated protein 4. OX-40 - AKA CD134 & TNFRSF4 = Tumor necrosis factor receptor superfamily, member 4) 2.25 Has received prior Vascular endothelial growth factor (VEGF) or VEGFR inhibitor therapy such as bevacizumab, cediranib, aflibercept, vandetanib, XL-184 (Cabozantinib), sunitinib, etc. (Cohort A only) Other Meds: 2.26 Is receiving any form of immunosuppressive therapy (e.g. chronic systemic steroid therapy exceeding dosage of 10 mg daily of prednisone equivalent) within 7 days prior to the first dose of study drug. 2.27 Has received systemic immunosuppressive treatments (aside from systemic corticosteroids as described in protocol) within six months of start of study drug (such as methotrexate, chloroquine, azathioprine, etc). 2.28 Requires treatment with high dose systemic corticosteroids defined as dexamethasone \> 2 mg/day or bioequivalent for at least 3 consecutive days within 2 weeks of start of study drug. * Inhaled or topical steroids and adrenal replacement doses \> 10 mg daily prednisone equivalents are permitted in the absence of active autoimmune disease. * Participants are permitted to use topical, ocular, intra-articular, intranasal, and inhalational corticosteroids (with minimal systemic absorption). * Physiologic replacement doses of systemic corticosteroids are permitted, even if \> 10 mg/day prednisone equivalents. * A brief course of corticosteroids for prophylaxis or for treatment of non-autoimmune conditions is permitted. 2.29 Requires therapeutic anticoagulation with warfarin at baseline; patients must be off warfarin or warfarin-derivative anti-coagulants for at least 7 days prior to starting study drug. (Therapeutic or prophylactic therapy with low-molecular weight heparin is allowed.) 2.30 Has received a live vaccine within 30 days prior to the first dose of study drug.

Design outcomes

Primary

MeasureTime frameDescription
Objective Response Rate (ORR)2 yearsPer Response Assessment in Neuro-Oncology (RANO) Criteria: * Complete Response (CR): * Disappearance of all enhancing measurable & non-measurable disease sustained for at least 4 weeks * No new lesions * Stable or improved non-enhancing (T2/FLAIR) lesions * No corticosteroids (or physiologic replacement doses only) * And stable or improved clinically * Partial Response (PR): * \>=50% decrease compared with baseline in the sum of products of perpendicular diameters of all measurable enhancing lesions sustained for at least 4 weeks; * No progression of non-measurable disease * No new lesions * Stable or improved non-enhancing (T2/FLAIR) lesions * Same or lower dose of corticosteroids compared with baseline scan * And stable or improved clinically Overall Response Rate (ORR) = Frequency of CR + PR within a population.
Overall Survival Rate at 6 Months (OS-6)6 months
Overall Survival Rate at 12 Months (OS-12)12 months

Secondary

MeasureTime frameDescription
6-month Progression Free Survival (PFS-6)6 monthsProgression is defined using Radiologic Assessment in Neuro-Oncology (RANO) criteria, as any of the following: * ≥ 25% increase in sum of the products of perpendicular diameters of enhancing lesions compared with the smallest tumor measurement, on stable or increasing doses of corticosteroids * Any new enhancing measurable lesion * Clear clinical deterioration not attributable to other causes apart from the tumor or changes in corticosteroid dose * Cohort B: Significant increase in T2/FLAIR non-enhancing lesions on stable or increasing doses of corticosteroids not felt to be caused by co-morbid events * Clear progression of non-measurable disease * Or failure to return for evaluation as a result of death or deteriorating condition
Safety & Tolerability: SAEs Experienced by Participants2 yearsNumber of Participants who Experienced an SAE Deemed At Least Possibly Related to Study Treatment (XRT, pembrolizumab, &/or bevacizumab)
Median Overall Survival (OS)Participants were followed for survival until death; survival was followed for a max of 4 years. Other Adverse Events (AEs) were collected from registration through 30 days after last dose (SAEs through 90 days); AEs were followed for a max of 2 years.
Duration of Response1 yearEach patient's response data is reviewed and the duration of his/her best response determined (in days).
Median Progression Free Survival (PFS)2 yearsProgression is defined using Radiologic Assessment in Neuro-Oncology (RANO) criteria, as any of the following: * ≥ 25% increase in sum of the products of perpendicular diameters of enhancing lesions compared with the smallest tumor measurement, on stable or increasing doses of corticosteroids * Any new enhancing measurable lesion * Clear clinical deterioration not attributable to other causes apart from the tumor or changes in corticosteroid dose * Cohort B: Significant increase in T2/FLAIR non-enhancing lesions on stable or increasing doses of corticosteroids not felt to be caused by co-morbid events * Clear progression of non-measurable disease * Or failure to return for evaluation as a result of death or deteriorating condition

Countries

United States

Participant flow

Participants by arm

ArmCount
COH A - Dose Level 0 (200 mg Pembro Once Every 3 Weeks + 2 Weeks of RT)
Inclusive of both Safety Lead-In & PH II COH A participants, as they were all treated at the same dose: * Pembrolizumab (200 mg) administered intravenously (IV) once every 3 weeks. * Re-irradiation (35 Gy) administered 5 days per week for 2 weeks
30
COH B - Dose Level 0 (200 mg Pembro + 15 mg/kg Bev Once Every 3 Weeks + 2 Weeks of RT)
Inclusive of both Safety Lead-In & PH II COH B participants, as they were all treated at the same dose: * Pembrolizumab (200 mg) administered intravenously (IV) once every 3 weeks. * Bevacizumab or biosimilar (15 mg/kg) administered intravenously (IV) once every 3 weeks * Re-irradiation (35 Gy) administered 5 days per week for 2 weeks
30
Total60

Withdrawals & dropouts

PeriodReasonFG000FG001FG002FG003
Overall StudyClinical Deterioration0001
Overall StudyDisease Progression424419
Overall StudyPhysician Decision1000
Overall StudyWithdrawal by Subject1024

Baseline characteristics

CharacteristicCOH B - Dose Level 0 (200 mg Pembro + 15 mg/kg Bev Once Every 3 Weeks + 2 Weeks of RT)COH A - Dose Level 0 (200 mg Pembro Once Every 3 Weeks + 2 Weeks of RT)Total
Age, Categorical
<=18 years
0 Participants0 Participants0 Participants
Age, Categorical
>=65 years
8 Participants4 Participants12 Participants
Age, Categorical
Between 18 and 65 years
22 Participants26 Participants48 Participants
Age, Continuous61 years61 years61 years
Current Recurrence #
First Relapse
10 Participants19 Participants29 Participants
Current Recurrence #
Fourth Relapse
3 Participants0 Participants3 Participants
Current Recurrence #
Second Relapse
12 Participants11 Participants23 Participants
Current Recurrence #
Third Relapse
5 Participants0 Participants5 Participants
Dexamethasone Use @ Time On Study
No Dexamethasone
17 Participants24 Participants41 Participants
Dexamethasone Use @ Time On Study
Receiving Dexamethasone
13 Participants6 Participants19 Participants
Ethnicity (NIH/OMB)
Hispanic or Latino
5 Participants1 Participants6 Participants
Ethnicity (NIH/OMB)
Not Hispanic or Latino
17 Participants26 Participants43 Participants
Ethnicity (NIH/OMB)
Unknown or Not Reported
8 Participants3 Participants11 Participants
Extent of Resection Prior to Study Enrollment
Biopsy
0 Participants1 Participants1 Participants
Extent of Resection Prior to Study Enrollment
Gross Total Resection (GTR)
1 Participants8 Participants9 Participants
Extent of Resection Prior to Study Enrollment
None
29 Participants11 Participants40 Participants
Extent of Resection Prior to Study Enrollment
Sub-Total Resection (STR)
0 Participants6 Participants6 Participants
Extent of Resection Prior to Study Enrollment
Unknown
0 Participants4 Participants4 Participants
IDH mutation
Absent
26 Participants17 Participants43 Participants
IDH mutation
Present
3 Participants2 Participants5 Participants
IDH mutation
Unknown
1 Participants11 Participants12 Participants
Karnofsky performance status (KPS)
KPS = 100
1 Participants1 Participants2 Participants
Karnofsky performance status (KPS)
KPS = 70
9 Participants5 Participants14 Participants
Karnofsky performance status (KPS)
KPS = 80
12 Participants10 Participants22 Participants
Karnofsky performance status (KPS)
KPS = 90
8 Participants14 Participants22 Participants
MGMT Methylation Status
Methylated
11 Participants7 Participants18 Participants
MGMT Methylation Status
Unknown
5 Participants12 Participants17 Participants
MGMT Methylation Status
Unmethylated
14 Participants11 Participants25 Participants
Race (NIH/OMB)
American Indian or Alaska Native
0 Participants0 Participants0 Participants
Race (NIH/OMB)
Asian
1 Participants0 Participants1 Participants
Race (NIH/OMB)
Black or African American
1 Participants0 Participants1 Participants
Race (NIH/OMB)
More than one race
3 Participants2 Participants5 Participants
Race (NIH/OMB)
Native Hawaiian or Other Pacific Islander
0 Participants0 Participants0 Participants
Race (NIH/OMB)
Unknown or Not Reported
7 Participants1 Participants8 Participants
Race (NIH/OMB)
White
18 Participants27 Participants45 Participants
Region of Enrollment
United States
30 participants30 participants60 participants
Sex: Female, Male
Female
14 Participants14 Participants28 Participants
Sex: Female, Male
Male
16 Participants16 Participants32 Participants
Time from Original GBM Diagnosis to Trial Registration14.5 months13.5 months14 months

Adverse events

Event typeEG000
affected / at risk
EG001
affected / at risk
deaths
Total, all-cause mortality
30 / 3028 / 30
other
Total, other adverse events
30 / 3030 / 30
serious
Total, serious adverse events
14 / 3011 / 30

Outcome results

Primary

Objective Response Rate (ORR)

Per Response Assessment in Neuro-Oncology (RANO) Criteria: * Complete Response (CR): * Disappearance of all enhancing measurable & non-measurable disease sustained for at least 4 weeks * No new lesions * Stable or improved non-enhancing (T2/FLAIR) lesions * No corticosteroids (or physiologic replacement doses only) * And stable or improved clinically * Partial Response (PR): * \>=50% decrease compared with baseline in the sum of products of perpendicular diameters of all measurable enhancing lesions sustained for at least 4 weeks; * No progression of non-measurable disease * No new lesions * Stable or improved non-enhancing (T2/FLAIR) lesions * Same or lower dose of corticosteroids compared with baseline scan * And stable or improved clinically Overall Response Rate (ORR) = Frequency of CR + PR within a population.

Time frame: 2 years

Population: \# of participants in the analysis population who achieve a complete response (CR) or partial response (PR) using RANO criteria

ArmMeasureValue (COUNT_OF_PARTICIPANTS)
COH A - Dose Level 0 (200 mg Pembro Once Every 3 Weeks + 2 Weeks of RT)Objective Response Rate (ORR)1 Participants
COH B - Dose Level 0 (200 mg Pembro + 15 mg/kg Bev Once Every 3 Weeks + 2 Weeks of RT)Objective Response Rate (ORR)3 Participants
Primary

Overall Survival Rate at 12 Months (OS-12)

Time frame: 12 months

ArmMeasureValue (NUMBER)
COH A - Dose Level 0 (200 mg Pembro Once Every 3 Weeks + 2 Weeks of RT)Overall Survival Rate at 12 Months (OS-12)40.0 percentage of participants
COH B - Dose Level 0 (200 mg Pembro + 15 mg/kg Bev Once Every 3 Weeks + 2 Weeks of RT)Overall Survival Rate at 12 Months (OS-12)16.6 percentage of participants
Primary

Overall Survival Rate at 6 Months (OS-6)

Time frame: 6 months

ArmMeasureValue (NUMBER)
COH A - Dose Level 0 (200 mg Pembro Once Every 3 Weeks + 2 Weeks of RT)Overall Survival Rate at 6 Months (OS-6)83.3 percentage of participants
COH B - Dose Level 0 (200 mg Pembro + 15 mg/kg Bev Once Every 3 Weeks + 2 Weeks of RT)Overall Survival Rate at 6 Months (OS-6)56.7 percentage of participants
Secondary

6-month Progression Free Survival (PFS-6)

Progression is defined using Radiologic Assessment in Neuro-Oncology (RANO) criteria, as any of the following: * ≥ 25% increase in sum of the products of perpendicular diameters of enhancing lesions compared with the smallest tumor measurement, on stable or increasing doses of corticosteroids * Any new enhancing measurable lesion * Clear clinical deterioration not attributable to other causes apart from the tumor or changes in corticosteroid dose * Cohort B: Significant increase in T2/FLAIR non-enhancing lesions on stable or increasing doses of corticosteroids not felt to be caused by co-morbid events * Clear progression of non-measurable disease * Or failure to return for evaluation as a result of death or deteriorating condition

Time frame: 6 months

ArmMeasureValue (NUMBER)
COH A - Dose Level 0 (200 mg Pembro Once Every 3 Weeks + 2 Weeks of RT)6-month Progression Free Survival (PFS-6)13.3 percentage of participants
COH B - Dose Level 0 (200 mg Pembro + 15 mg/kg Bev Once Every 3 Weeks + 2 Weeks of RT)6-month Progression Free Survival (PFS-6)10.6 percentage of participants
Secondary

Duration of Response

Each patient's response data is reviewed and the duration of his/her best response determined (in days).

Time frame: 1 year

Population: 5 COH B patients were censored for duration of response, as they each withdrew consent to be followed (or initiated a new therapy regimen) right after a scan that showed stable disease.

ArmMeasureValue (MEDIAN)
COH A - Dose Level 0 (200 mg Pembro Once Every 3 Weeks + 2 Weeks of RT)Duration of Response79.5 days
COH B - Dose Level 0 (200 mg Pembro + 15 mg/kg Bev Once Every 3 Weeks + 2 Weeks of RT)Duration of Response42.0 days
Secondary

Median Overall Survival (OS)

Time frame: Participants were followed for survival until death; survival was followed for a max of 4 years. Other Adverse Events (AEs) were collected from registration through 30 days after last dose (SAEs through 90 days); AEs were followed for a max of 2 years.

ArmMeasureValue (MEDIAN)Dispersion
COH A - Dose Level 0 (200 mg Pembro Once Every 3 Weeks + 2 Weeks of RT)Median Overall Survival (OS)11.8 monthsStandard Error 1.0262
COH B - Dose Level 0 (200 mg Pembro + 15 mg/kg Bev Once Every 3 Weeks + 2 Weeks of RT)Median Overall Survival (OS)8.6 monthsStandard Error 1.1766
Secondary

Median Progression Free Survival (PFS)

Progression is defined using Radiologic Assessment in Neuro-Oncology (RANO) criteria, as any of the following: * ≥ 25% increase in sum of the products of perpendicular diameters of enhancing lesions compared with the smallest tumor measurement, on stable or increasing doses of corticosteroids * Any new enhancing measurable lesion * Clear clinical deterioration not attributable to other causes apart from the tumor or changes in corticosteroid dose * Cohort B: Significant increase in T2/FLAIR non-enhancing lesions on stable or increasing doses of corticosteroids not felt to be caused by co-morbid events * Clear progression of non-measurable disease * Or failure to return for evaluation as a result of death or deteriorating condition

Time frame: 2 years

ArmMeasureValue (MEDIAN)Dispersion
COH A - Dose Level 0 (200 mg Pembro Once Every 3 Weeks + 2 Weeks of RT)Median Progression Free Survival (PFS)4.2 monthsStandard Error 0.4551
COH B - Dose Level 0 (200 mg Pembro + 15 mg/kg Bev Once Every 3 Weeks + 2 Weeks of RT)Median Progression Free Survival (PFS)4.0 monthsStandard Error 0.5467
Secondary

Safety & Tolerability: SAEs Experienced by Participants

Number of Participants who Experienced an SAE Deemed At Least Possibly Related to Study Treatment (XRT, pembrolizumab, &/or bevacizumab)

Time frame: 2 years

ArmMeasureValue (COUNT_OF_PARTICIPANTS)
COH A - Dose Level 0 (200 mg Pembro Once Every 3 Weeks + 2 Weeks of RT)Safety & Tolerability: SAEs Experienced by Participants6 Participants
COH B - Dose Level 0 (200 mg Pembro + 15 mg/kg Bev Once Every 3 Weeks + 2 Weeks of RT)Safety & Tolerability: SAEs Experienced by Participants7 Participants

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026