Pevonedistat, a first-in-class NEDD8-activating enzyme inhibitor, combined with azacitidine in patients with AML.

Pevonedistat (TAK-924/MLN4924) is a novel inhibitor of NEDD8-activating enzyme (NAE) with single-agent activity in relapsed/refractory acute myeloid leukemia (AML). We performed a phase 1b study of pevonedistat (PEV) with azacitidine (AZA) based on synergistic activity seen preclinically. Primary objectives included safety and tolerability, and secondary objectives included pharmacokinetics (PK) and disease response. Patients ≥60 years with treatment-naive AML (unfit for standard induction therapy) received PEV 20 or 30 mg/m2 IV on days 1, 3, and 5 combined with fixed-dose AZA (75 mg/m2 IV/subcutaneously) on days 1 to 5, 8, and 9, every 28 days. The most common treatment-emergent adverse events were constipation (48%), nausea (42%), fatigue (42%), and anemia (39%). In total, 11 deaths were observed and considered unrelated to study therapy by the investigators. Transient elevations in aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were dose limiting. The recommended phase 2 dose (RP2D) of PEV in this combination is 20 mg/m2 PEV PK was not altered by the addition of AZA. Overall response rate (ORR) based on an intent-to-treat analysis was 50% (20 complete remissions [CRs], 5 complete remission with incomplete peripheral count recovery, 7 partial remissions [PRs]), with an 8.3-month median duration of remission. In patients receiving ≥6 cycles of therapy (n = 23, 44%), ORR was 83%. In patients with TP53 mutations, the composite CR/PR rate was 80% (4/5). Two of these patients stayed on study for >10 cycles. Baseline bone marrow blast percentage or cytogenetic/molecular risk did not influence ORR. This study was registered at www.clinicaltrials.gov as #NCT01814826.

Phase Ib study of pevonedistat, a NEDD8-activating enzyme inhibitor, in combination with docetaxel, carboplatin and paclitaxel, or gemcitabine, in patients with advanced solid tumors.

Purpose This phase Ib study (NCT01862328) evaluated the maximum tolerated dose (MTD), safety, and efficacy of pevonedistat in combination with standard-of-care chemotherapies in patients with solid tumors. Methods Patients received pevonedistat with docetaxel (arm 1, n = 22), carboplatin plus paclitaxel (arm 2, n = 26), or gemcitabine (arm 3, n = 10) in 21-days (arms 1 and 2) or 28-days (arm 3) cycles. A lead-in cohort (arm 2a, n = 6) determined the arm 2 carboplatin dose. Dose escalation proceeded via continual modified reassessment. Results Pevonedistat MTD was 25 mg/m2 (arm 1) or 20 mg/m2 (arm 2); arm 3 was discontinued due to poor tolerability. Fifteen (23%) patients experienced dose-limiting toxicities during cycle 1 (grade ≥3 liver enzyme elevations, febrile neutropenia, and thrombocytopenia), managed with dose holds or reductions. Drug-related adverse events (AEs) occurred in 95% of patients. Most common AEs included fatigue (56%) and nausea (50%). One drug-related death occurred in arm 3 (febrile neutropenia). Pevonedistat exposure increased when co-administered with carboplatin plus paclitaxel; no obvious changes were observed when co-administered with docetaxel or gemcitabine. Among 54 response-evaluable patients, two had complete responses (arm 2) and 10 had partial responses (three in arm 1, one in arm 2a, six in arm 2); overall response rates were 16% (arm 1) and 35% (arm 2). High ERCC1 expression correlated with clinical benefit in arm 2. Conclusion Pevonedistat with docetaxel or with carboplatin plus paclitaxel was tolerable without cumulative toxicity. Sustained clinical responses were observed in pretreated patients receiving pevonedistat with carboplatin and paclitaxel. ClinicalTrials.gov identifier: NCT01862328.

A phase I study of the investigational NEDD8-activating enzyme inhibitor pevonedistat (TAK-924/MLN4924) in patients with metastatic melanoma.

Purpose The therapeutic index of proteasome inhibitors may be improved through selective inhibition of a sub-component of the ubiquitin-proteasome system, such as the NEDD8-conjugation pathway. This multicenter, phase I, dose-escalation study assessed safety and the maximum tolerated dose (MTD), pharmacokinetics, pharmacodynamics, and antitumor activity of pevonedistat, an investigational NEDD8-activating enzyme (NAE) inhibitor, in patients with metastatic melanoma. Methods Patients received intravenous pevonedistat on Days 1, 4, 8, 11 (schedule A) or 1, 8, 15 (schedule B) of 21-day cycles. Results 26 patients received pevonedistat 50-278 mg/m(2) on schedule A; 11 patients received pevonedistat 157 mg/m(2) on schedule B. The schedule A MTD was 209 mg/m(2): dose-limiting toxicities (DLTs) included grade 3 hypophosphatemia and grade 3 increased blood creatinine (associated with grade 3 hyperbilirubinemia). Two schedule A patients experienced acute organ failure toxicities, one of whom experienced grade 5 acute renal failure. Dose escalation did not occur in schedule B: DLTs included grade 3 myocarditis, grade 2 acute renal failure, and grade 2 hyperbilirubinemia in a single patient. Pevonedistat pharmacokinetics were approximately dose-proportional across the dose range studied, with a biphasic disposition profile characterized by a short elimination half-life (~10 h). Pharmacodynamic studies showed increases in NAE-regulated transcripts post-treatment; all post-dose biopsy samples were positive for pevonedistat-NEDD8 adduct. One schedule A patient achieved a partial response; 15 patients had stable disease (4 lasting ≥6.5 months). Conclusions Pevonedistat was generally well tolerated at the MTD. Anticipated pharmacodynamic effects of NAE inhibition were observed with single-agent pevonedistat in peripheral blood and tumor tissue.

Pevonedistat (MLN4924), a First-in-Class NEDD8-activating enzyme inhibitor, in patients with acute myeloid leukaemia and myelodysplastic syndromes: a phase 1 study.

This trial was conducted to determine the dose-limiting toxicities (DLTs) and maximum tolerated dose (MTD) of the first in class NEDD8-activating enzyme (NAE) inhibitor, pevonedistat, and to investigate pevonedistat pharmacokinetics and pharmacodynamics in patients with acute myeloid leukaemia (AML) and myelodysplastic syndromes (MDS). Pevonedistat was administered via a 60-min intravenous infusion on days 1, 3 and 5 (schedule A, n = 27), or days 1, 4, 8 and 11 (schedule B, n = 26) every 21-days. Dose escalation proceeded using a standard '3 + 3' design. Responses were assessed according to published guidelines. The MTD for schedules A and B were 59 and 83 mg/m(2) , respectively. On schedule A, hepatotoxicity was dose limiting. Multi-organ failure (MOF) was dose limiting on schedule B. The overall complete (CR) and partial (PR) response rate in patients treated at or below the MTD was 17% (4/23, 2 CRs, 2 PRs) for schedule A and 10% (2/19, 2 PRs) for schedule B. Pevonedistat plasma concentrations peaked after infusion followed by elimination in a biphasic pattern. Pharmacodynamic studies of biological correlates of NAE inhibition demonstrated target-specific activity of pevonedistat. In conclusion, administration of the first-in-class agent, pevonedistat, was feasible in patients with MDS and AML and modest clinical activity was observed.

Cutaneous keratoacanthomas/squamous cell carcinomas associated with neutralization of transforming growth factor ß by the monoclonal antibody fresolimumab (GC1008).

Fresolimumab is an antibody capable of neutralizing all human isoforms of transforming growth factor beta (TGFß) and has demonstrated anticancer activity in investigational studies. Inhibition of TGFß by fresolimumab can potentially result in the development of cutaneous lesions. The aim of this study was to investigate the clinical, histological, and immunohistochemical characteristics of cutaneous neoplasms associated with fresolimumab. Skin biopsies (n = 24) were collected and analyzed from patients (n = 5) with treatment-emergent, cutaneous lesions arising during a phase 1 study of multiple doses of fresolimumab in patients (n = 29) with melanoma or renal cell carcinoma. Blinded, independent histological review and measurements of Ki-67, p53, and HPV integration were performed. Based on central review, four patients developed lesions with histological characteristics of keratoacanthomas, and of these patients, a single case of well-differentiated squamous cell carcinoma was also found. Expression of Ki-67, no evidence of p53 overexpression, and only focal positivity for human papillomavirus RNA by in situ hybridization in 4/18 cases were consistent with these findings. Following completion of fresolimumab, lesions spontaneously resolved. Therefore, benign, reversible keratoacanthomas were the most common cutaneous neoplasms observed, a finding of importance for adverse event monitoring, patient care, and optimization of therapies targeting TGFß.

A phase 1/pharmacokinetic study of sunitinib in combination with highly active antiretroviral therapy in human immunodeficiency virus-positive patients with cancer: AIDS Malignancy Consortium trial AMC 061.

BACKGROUND: The treatment of non-acquired immunodeficiency syndrome-defining cancers may be complicated by drug interactions between highly active antiretroviral therapy (HAART) and chemotherapy. This trial is the first by the AIDS Malignancy Consortium to assess targeted therapies and HAART in human immunodeficiency virus-positive patients (ClinicalTrials.gov identifier: NCT00890747). METHODS: In a modified phase 1 study of sunitinib, patients were stratified into 2 treatment arms based on whether they were receiving therapy with ritonavir, a potent CYP3A4 inhibitor. Patients in treatment arm 1 (non-ritonavir HAART) received standard sunitinib dosing (50 mg/day). Treatment arm 2 (ritonavir-based HAART) used a phase 1, 3 + 3 dose escalation design (from 25 mg/day to 50 mg/day). Cycles were comprised of 4 weeks on treatment followed by a 2-week break (6 weeks total). The pharmacokinetics of sunitinib and its active metabolite (N-desethyl sunitinib) were assessed. RESULTS: Nineteen patients were enrolled and were evaluable. Patients on treatment arm 1 tolerated treatment with no dose-limiting toxicity observed. In treatment arm 2, a dose-limiting toxicity was experienced at a dose of 37.5 mg, and an additional 3 of 5 patients experienced grade 3 neutropenia (toxicity graded as per National Cancer Institute Common Terminology Criteria for Adverse Events [version 4.0]), an uncommon toxicity of sunitinib. No patient achieved a response, but 10 patients had stable disease, including 8 with prolonged disease stability. Efavirenz, a potent inducer of CYP3A4, resulted in increased exposure of N-desethyl sunitinib, whereas ritonavir caused decreased exposure of the metabolite. Hand-foot syndrome was associated with higher steady-state trough concentrations of sunitinib. CONCLUSIONS: Patients receiving non-ritonavir-based HAART regimens tolerated standard dosing of sunitinib. Patients receiving ritonavir-based therapy who were treated with a dose of 37.5 mg/day experienced higher toxicities. Dose reductions of sunitinib to 37.5 mg may be warranted in patients receiving ritonavir.

Anaplastic lymphoma kinase inhibition in non-small-cell lung cancer.

BACKGROUND: Oncogenic fusion genes consisting of EML4 and anaplastic lymphoma kinase (ALK) are present in a subgroup of non-small-cell lung cancers, representing 2 to 7% of such tumors. We explored the therapeutic efficacy of inhibiting ALK in such tumors in an early-phase clinical trial of crizotinib (PF-02341066), an orally available small-molecule inhibitor of the ALK tyrosine kinase. METHODS: After screening tumor samples from approximately 1500 patients with non-small-cell lung cancer for the presence of ALK rearrangements, we identified 82 patients with advanced ALK-positive disease who were eligible for the clinical trial. Most of the patients had received previous treatment. These patients were enrolled in an expanded cohort study instituted after phase 1 dose escalation had established a recommended crizotinib dose of 250 mg twice daily in 28-day cycles. Patients were assessed for adverse events and response to therapy. RESULTS: Patients with ALK rearrangements tended to be younger than those without the rearrangements, and most of the patients had little or no exposure to tobacco and had adenocarcinomas. At a mean treatment duration of 6.4 months, the overall response rate was 57% (47 of 82 patients, with 46 confirmed partial responses and 1 confirmed complete response); 27 patients (33%) had stable disease. A total of 63 of 82 patients (77%) were continuing to receive crizotinib at the time of data cutoff, and the estimated probability of 6-month progression-free survival was 72%, with no median for the study reached. The drug resulted in grade 1 or 2 (mild) gastrointestinal side effects. CONCLUSIONS: The inhibition of ALK in lung tumors with the ALK rearrangement resulted in tumor shrinkage or stable disease in most patients. (Funded by Pfizer and others; ClinicalTrials.gov number, NCT00585195.).

Lymphatic reprogramming of blood vascular endothelium by Kaposi sarcoma-associated herpesvirus.

Kaposi sarcoma is considered a neoplasm of lymphatic endothelium infected with Kaposi sarcoma-associated herpesvirus. It is characterized by the expression of lymphatic lineage-specific genes by Kaposi sarcoma tumor cells. Here we show that infection of differentiated blood vascular endothelial cells with Kaposi sarcoma-associated herpesvirus leads to their lymphatic reprogramming; induction of approximately 70% of the main lymphatic lineage-specific genes, including PROX1, a master regulator of lymphatic development; and downregulation of blood vascular genes.

The rising challenge of non-AIDS-defining cancers in HIV-infected patients.

Since the advent of HAART, patients with HIV infection have seen a significant improvement in their morbidity, mortality, and life expectancy. The incidence of AIDS-defining illnesses, including AIDS-defining malignancies, has been on the decline. However, deaths due to non-AIDS-defining illnesses have been on the rise. These so-called non-AIDS-defining cancers (NADCs) include cancers of the lung, liver, kidney, anus, head and neck, and skin, as well as Hodgkin's lymphoma. It is poorly understood why this higher rate of NADCs is occurring. The key challenge facing oncologists is how to administer chemotherapy effectively and safely to patients on antiretroviral therapy. The challenge to clinicians caring for HIV-infected patients is to develop and implement effective means to screen, treat, and prevent NADCs in the future. This review presents data on the epidemiology and etiology of NADCs, as well as ongoing research into this evolving aspect of the HIV epidemic.

Nuclear factor kappa B pathway associated biomarkers in AIDS defining malignancies.

The nuclear factor kappa B (NFκB) pathway is essential for many human cancers. Therapeutics such as bortezomib (Velcade™) that interfere with NFκB signaling are of great clinical interest. NFκB signaling, however, is multifaceted and variable among tissues, developmental and disease entities. Hence, targeted biomarkers of NFκB pathways are of prime importance for clinical research. We developed a novel real-time qPCR-based NFκB array. Only mechanistically validated NFκB targets were included. We then used random-forest classification to define individual genes and gene combinations within the NFκB pathways that define viral lymphoma subclasses as well as Kaposi sarcoma (KS). Few NFκB targets emerged that were universally present in all tumor types tested, underscoring the need for additional tumor-type specific biomarker discovery. (i) We uncovered tissue of origin-specific tumor markers, specifically CD69, CSF-1 and complement factor B (C1QBP) for primary effusion lymphoma (PEL); IL1-beta, cyclinD3 and CD48 for KS. We found that IL12, jun-B, msx-1 and thrombospondin 2 were associated with EBV co-infection in PEL. (ii) We defined the NFκB signature of Epstein-Barr virus (EBV) positive AIDS-associated Burkitt lymphoma (BL). This signature identified CCR5 as the key marker. (iii) This signature differed from EBV negative BL consistent with the idea that EBV not only activates NFκB activity but that this virus also reprograms NFκB signaling toward different targets.

Rituximab plus concurrent infusional EPOCH chemotherapy is highly effective in HIV-associated B-cell non-Hodgkin lymphoma.

Rituximab plus intravenous bolus chemotherapy is a standard treatment for immunocompetent patients with B-cell non-Hodgkin lymphoma (NHL). Some studies have suggested that rituximab is associated with excessive toxicity in HIV-associated NHL, and that infusional chemotherapy may be more effective. We performed a randomized phase 2 trial of rituximab (375 mg/m(2)) given either concurrently before each infusional etoposide, vincristine, doxorubicin, cyclophosphamide, and prednisone (EPOCH) chemotherapy cycle or sequentially (weekly for 6 weeks) after completion of all chemotherapy in HIV-associated NHL. EPOCH consisted of a 96-hour intravenous infusion of etoposide, doxorubicin, and vincristine plus oral prednisone followed by intravenous bolus cyclophosphamide given every 21 days for 4 to 6 cycles. In the concurrent arm, 35 of 48 evaluable patients (73%; 95% confidence interval, 58%-85%) had a complete response. In the sequential arm, 29 of 53 evaluable patients (55%; 95% confidence interval, 41%-68%) had a complete response. The primary efficacy endpoint was met for the concurrent arm only. Toxicity was comparable in the 2 arms, although patients with a baseline CD4 count less than 50/microL had a high infectious death rate in the concurrent arm. We conclude that concurrent rituximab plus infusional EPOCH is an effective regimen for HIV-associated lymphoma.

Efficacy of short-term monotherapy with maraviroc, a new CCR5 antagonist, in patients infected with HIV-1.

We assessed the efficacy and safety of 10-d monotherapy with the orally administered CCR5 antagonist maraviroc in 63 HIV-1-positive individuals prescreened for the absence of CXCR4-using virus. Maximum reduction in viral load occurred at a median of 10-15 d, with a mean reduction of >or=1.6 log(10) copies/ml at all twice daily doses >or=100 mg. These results provide proof of concept that CCR5 antagonism is a viable antiretroviral therapeutic approach.

IOLite: phase 1b trial of doublet/triplet combinations of dostarlimab with niraparib, carboplatin-paclitaxel, with or without bevacizumab in patients with advanced cancer.

BACKGROUND: Doublet combination therapies targeting immune checkpoints have shown promising efficacy in patients with advanced solid tumors, but it is unknown if rational triplet combinations will be well tolerated and associated with improved antitumor activity. The objective of this trial was to determine the recommended phase 2 doses (RP2Ds) and to assess the safety and efficacy of the programmed cell death protein 1 (PD-1) inhibitor dostarlimab in combination with (1) the poly(ADP-ribose) polymerase inhibitor niraparib with or without vascular endothelial growth factor inhibitor bevacizumab or (2) carboplatin-paclitaxel chemotherapy with or without bevacizumab, in patients with advanced cancer. METHODS: IOLite is a multicenter, open-label, multi-arm clinical trial. Patients with advanced solid tumors were enrolled. Patients received dostarlimab in combination with niraparib with or without bevacizumab or in combination with carboplatin-paclitaxel with or without bevacizumab until disease progression, unacceptable toxicity, or withdrawal from the study. Prespecified endpoints in all parts were to evaluate the dose-limiting toxicities (DLTs), RP2Ds, pharmacokinetics (PKs), and preliminary efficacy for each combination. RESULTS: A total of 55 patients were enrolled; patients received dostarlimab and: (1) niraparib in part A (n=22); (2) carboplatin-paclitaxel in part B (n=14); (3) niraparib plus bevacizumab in part C (n=13); (4) carboplatin-paclitaxel plus bevacizumab in part D (n=6). The RP2Ds of all combinations were determined. All combinations were safe and tolerable, with no new safety signals observed. DLTs were reported in 2, 1, 2, and 0 patients, in parts A-D, respectively. Preliminary antitumor activity was observed, with confirmed Response Evaluation Criteria in Solid Tumors v1.1 complete/partial responses reported in 4 of 22 patients (18.2%), 6 of 14 patients (42.9%), 4 of 13 patients (30.8%), and 3 of 6 (50.0%) patients, in parts A-D, respectively. Disease control rates were 40.9%, 57.1%, 84.6%, and 83.3%, in parts A-D, respectively. Dostarlimab PK was unaffected by any combinations tested. Coadministration of bevacizumab showed no impact on niraparib PKs. The overall mean PD-1 receptor occupancy was 99.0%. CONCLUSIONS: Dostarlimab was well tolerated in both doublet and triplet regimens tested, with promising antitumor activity observed with all combinations. We observed higher disease control rates in the triplet regimens than in doublet regimens. TRIAL REGISTRATION NUMBER: NCT03307785.

Pre-micro RNA signatures delineate stages of endothelial cell transformation in Kaposi sarcoma.

MicroRNAs (miRNA) have emerged as key regulators of cell lineage differentiation and cancer. We used precursor miRNA profiling by a novel real-time QPCR method (i) to define progressive stages of endothelial cell transformation cumulating in Kaposi sarcoma (KS) and (ii) to identify specific miRNAs that serve as biomarkers for tumor progression. We were able to compare primary patient biopsies to well-established culture and mouse tumor models. Loss of mir-221 and gain of mir-15 expression demarked the transition from merely immortalized to fully tumorigenic endothelial cells. Mir-140 and Kaposi sarcoma-associated herpesvirus viral miRNAs increased linearly with the degree of transformation. Mir-24 emerged as a biomarker specific for KS.

Tumor suppressor microRNAs are underrepresented in primary effusion lymphoma and Kaposi sarcoma.

The presence of tumor-specific microRNAs reflects tissue of origin and tumor stage. We show that the absence of miRNAs likewise can be used to determine tumor origin (miR-155) and proliferation state because tumor suppressor miRNAs (miR-222/221, let-7 family) were significantly down-regulated in primary effusion lymphoma (PEL) and in Kaposi sarcoma (KS), an endothelial cell tumor. PEL and KS are associated with KS-associated herpesvirus infection. We identified 15 virally regulated miRNAs in latently infected, nontumorigenic endothelial cells. MiR-143/145 were elevated only in KS tumors, not virally infected endothelial cells. Thus, they represent tumor-specific, rather than virus-specific, miRNAs. Because many tumor suppressor proteins are wild-type in KS and PEL, down-regulation of multiple tumor suppressor miRNAs provides a novel, alternative mechanism of transformation.

Antimicrobial and non-antimicrobial tetracyclines in human cancer trials.

Tetracyclines are capable of inhibiting mammalian collagenases by non-antimicrobial mechanisms. Because collagenases and other matrix metalloproteinases have been linked to cancer pathogenesis, this property of tetracycline's has led to speculation that these drugs could be used to slow tumor growth, invasion and metastasis in neoplasms that overly express these enzymes. The FDA has already approved two tetracycline derivates for treatment of chronic inflammatory periodontal disease and chronic inflammatory skin disease. Here we review the efforts to determine the efficacy of tetracyclines as chemotherapeutics in human cancer trials. While the majority of clinical trials have yielded disappointing results, tetracyclines have been shown to be generally well tolerated and have significant anti-proliferative effects in certain cancer types. In particular the chemically modified tetracycline derivative COL-3 (also known as CMT-3) has been shown to cause dramatic improvement in the tumor burden of patients with Kaposi Sarcoma. The experience using tetracyclines as chemotherapeutics is relatively limited, but further success is possible if future trials are focused on specific cancer subtypes that are known to rely heavily on collagenases and other matrix metalloproteinases for their pathogenesis.

Frequency of occult high-grade squamous intraepithelial neoplasia and invasive cancer within anal condylomata in men who have sex with men.

Human papillomavirus causes anal condylomata, high-grade anal intraepithelial neoplasia, and anal squamous cell cancer. We found high-grade intraepithelial neoplasia or squamous cell cancer in 75 (47%) of 159 HIV-seropositive men who have sex with men (MSM) and in 42 (26%) of 160 HIV-seronegative MSM with anal condylomata meriting surgery (P<.001, determined by use of the chi(2) test). Anal condylomata in MSM often harbor high-grade intraepithelial neoplasia and squamous cell cancer.

Time for oncologists to opt in for routine opt-out HIV testing?

Human immunodeficiency virus (HIV)-infected individuals are at high risk of malignancies. However, it is not currently the standard of care to routinely test cancer patients for HIV. In 2006, the Centers for Disease Control and Prevention recommended HIV testing in all health care settings, calling for standard nontargeted "opt-out" HIV screening. For a variety of reasons, routine opt-out HIV testing is still not widely used in the United States. Although many barriers to routine opt-out HIV testing have been addressed, such opt-out HIV testing continues to be conducted primarily in venues that target specific patient populations such as pregnant women. Although opt-out testing has been piloted in emergency departments, less emphasis has been placed on opt-out HIV testing in other clinical settings. In this article, the background, rationale, and evidence for supporting opt-out HIV testing as routine care for cancer patients are presented. In addition, evidence is discussed for the potential of opt-out HIV testing to improve clinical outcomes by facilitating appropriate HIV management during cancer treatment for individuals who are found to be HIV positive.

Letter: Kaposi sarcoma versus nephrogenic systemic fibrosis.

The histopathology of particular Kaposi saroma (KS) variants may closely resemble that seen in nephrogenic systemic fibrosis (NSF). Given that NSF skin lesions are negative for HHV8 (LNA-1), this immunohistochemical marker can be used to distinguish these two entities.

Immunogenomic profiling determines responses to combined PARP and PD-1 inhibition in ovarian cancer.

Combined PARP and immune checkpoint inhibition has yielded encouraging results in ovarian cancer, but predictive biomarkers are lacking. We performed immunogenomic profiling and highly multiplexed single-cell imaging on tumor samples from patients enrolled in a Phase I/II trial of niraparib and pembrolizumab in ovarian cancer (NCT02657889). We identify two determinants of response; mutational signature 3 reflecting defective homologous recombination DNA repair, and positive immune score as a surrogate of interferon-primed exhausted CD8 + T-cells in the tumor microenvironment. Presence of one or both features associates with an improved outcome while concurrent absence yields no responses. Single-cell spatial analysis reveals prominent interactions of exhausted CD8 + T-cells and PD-L1 + macrophages and PD-L1 + tumor cells as mechanistic determinants of response. Furthermore, spatial analysis of two extreme responders shows differential clustering of exhausted CD8 + T-cells with PD-L1 + macrophages in the first, and exhausted CD8 + T-cells with cancer cells harboring genomic PD-L1 and PD-L2 amplification in the second.