Citations

As machine learning (ML)-based decision support tools proliferate in clinical practice, understanding how clinicians integrate personalized ML predictions alongside randomized controlled trial (RCT) evidence is critical. We designed a web-based clinical decision support system (CDSS) presenting survival and adverse event data from a simulated RCT and ML model across 12 synthetic multiple myeloma scenarios. In a within-subjects study with 32 physicians, we evaluated how clinicians synthesize competing evidence sources to make treatment decisions. When ML and RCT outputs were concordant, physicians reported greater confidence than with RCT data alone. When results were discordant, most physicians shifted toward the ML-supported treatment, often before reviewing any information about model training or validation, suggesting a tendency toward automation bias rather than algorithm avoidance. Despite reporting higher perceived reliability after viewing model quality disclosures, physicians were largely unable to describe the validation procedures they had reviewed. Taken together, these findings reveal that clinicians may over-rely on ML recommendations even when equipped with tools designed to support critical appraisal. We discuss implications for CDSS design, clinician training, and the institutional safeguards needed before ML-based systems are deployed in high-stakes oncology settings.

Abstract Introduction The treatment of newly diagnosed multiple myeloma (NDMM) has rapidly evolved. Quadruplet induction combining an anti-CD38 monoclonal antibody, lenalidomide, a proteasome inhibitor, and dexamethasone has become a standard of care. In this prospective randomized phase 2 trial, we evaluated the efficacy and safety of induction with a four-drug combination of daratumumab (Dara), lenalidomide (R), ixazomib (I), and dexamethasone (d) (Dara-RId) in older, transplant ineligible or deferred patients, followed by maintenance with Dara RI versus R for up to 2 years. We hypothesized that this quadruplet would offer improved tolerability with less peripheral neuropathy in this older population as well as the convenience of largely oral therapy. Herein, we present the initial results of the induction phase of the study. Methods Transplant-ineligible or deferred patients with NDMM were eligible to participate. This was a multicenter trial sponsored by the Alliance Foundation Trials, LLC, AFT-41 (NCT04009109). Each cycle of treatment was 28 days. All patients received 12 cycles of induction therapy with daratumumab 1800 mg subcutaneously on the conventional schedule, lenalidomide 15 mg orally (po) on days 1-21, ixazomib 4 mg po on days 1, 8, 15, and dexamethasone weekly. After 12 cycles, patients received maintenance based on prior randomization (1:1) to Dara-RI or R for up to 2 years. In maintenance, R was reduced to 10 mg and I was reduced to 3 mg. Randomization assignment occurred prior to starting induction. Stratification was based on presence of high-risk features defined as ISS stage III or high-risk FISH cytogenetics (del 17, t (14;16), t (14;20), t (4;14), del (1p), or gain (1q)). The primary endpoint was progression-free survival (PFS). Secondary endpoints included objective response rate (ORR) and adverse events. Results We enrolled 79 patients across 7 sites from October 2020 until December 2023. Accrual was affected by the COVID19 pandemic, leading to early closure to accrual in December 2023. Median age was 74 years (range 63-86); ≥75 years of age (45.6%); female (59.5%); white (83.5%), African American (7.6%), Asian (1.3%), and Hispanic ethnicity (6.3%). Additional baseline characteristics included ISS staging I (41.8%), II (35.4%), and III (22.8%) with high-risk features in 37% by ISS stage III and/or high-risk FISH. The 12-month PFS was 92% (95% confidence interval [CI] 86.1-98.4%). The ORR (≥ partial response [PR]) during induction was 92.4% (PR 22.8%; very good partial response [VGPR] 46.8%; complete response 15.2%; stringent complete response 7.6%). Notable grade ≥3 adverse events included neutropenia (16.5%), infections (11.4%), anemia (10.1%), thrombocytopenia (8.9%), and syncope (7.6%). There was no grade ≥3 peripheral neuropathy (grade 1, 15%; grade 2, 14%). No treatment-related mortality was reported. Sixty-one patients went on to maintenance therapy and seven patients discontinued treatment for adverse events during induction (8.9%). Conclusions Dara-RId therapy in NDMM appears to be efficacious with an ORR of 92.4%; VGPR or better of 69.6% and 12-month PFS of 92%. The combination was generally tolerated well with manageable toxicity, despite 45.6% of patients being ≥75, offering the convenience of an oral proteasome inhibitor, ixazomib, that minimizes the risk of peripheral neuropathy for older, transplant-ineligible or deferred patients. Follow-up is ongoing to determine the benefit of maintenance with Dara-RI v. R alone in this population. Support: AFT, Celgene, Janssen, Takeda.

Abstract Background Translocation of chromosomes 4 and 14 (t(4;14)) results in overexpression of MMSET and has been associated with poor clinical outcomes in patients (pts) with multiple myeloma (MM). KTX-1001 is a first-in-class, potent, and selective oral inhibitor of MMSET (also known as NSD2) developed as the first investigational therapy to directly target the high-risk t(4;14) translocation, a key molecular driver in MM. KTX-1001 binds to and inhibits the catalytic SET domain of MMSET, thereby suppressing the deposition of dimethylated histone H3 lysine 36 (H3K36me2), leading to downregulation of oncogenic histone modifications and epigenetic reprogramming of malignant plasma cells. Preclinically, KTX-1001 synergistically inhibited cell viability in MM cell lines when combined with a proteasome inhibitor (PI), immunomodulatory drug (IMiD), or cereblon E3 ligase modulator (CELMoD™). Preliminary findings were previously reported from the initial cohort of 18 pts enrolled in a first-in-human phase 1 trial evaluating KTX-1001 in relapsed/refractory multiple myeloma (RRMM; NCT05651932; Bories et al. Blood. 2024;144[Suppl 1]:3370). Here, we present updated results from this study. Methods RRMM pts who received ≥3 prior therapies, including PI, IMiD and anti-CD38 monoclonal antibody (anti-CD38 mAb), received oral KTX-1001 across 9 dose levels using a 3+3 dose-escalation design. Primary objective was to determine the recommended Phase 2 dose (RP2D) and the maximum tolerated dose (MTD). Secondary objectives included pharmacokinetics, pharmacodynamics (PD), and primary efficacy. The dose expansion phase has been initiated to evaluate KTX-1001 in combination with either carfilzomib or the investigational CELMoD™ mezigdomide in t(4;14) RRMM pts. Results As of 13 June 2025, 40 pts have been treated in the monotherapy dose-escalation phase. The maximum tolerated dose (MTD) was exceeded due to dose-limiting toxicities (DLTs) in 2 pts: two Grade (Gr) 4 thrombocytopenia and one Gr 3 epistaxis. Backfill at selected dose levels is ongoing to further characterize safety profile and refine dose optimization. The median time from initial MM diagnosis was 8 years (range:2-20) with a median of 6.5 prior lines of therapy (range: 3-25). This included stem cell transplant (70%), BCMA CAR-T (42.5%), and non-CAR-T BCMA targeted drugs such as antibody-drug conjugates and bispecific antibodies (57.5%). The median age was69 years (range:50-83); 21 were female and 19 were male. Extra-medullary disease was present in 13 (32.5%) pts. Nineteen (47.5%) pts had t(4;14) translocation, 5 (12.5%) had 1q21 gain and 4 (10%) had deletion 17p. A total of 16 (40%) pts have shown a treatment response according to IMWG criteria or have achieved stable disease: 1 VGPR (10+ months), 1 PR (4+ months), 2 MR (3+ and 12 months), 12 SD (2-20+ months). KTX-1001 has demonstrated a favorable tolerability profile. Grade 3 or higher treatment-emergent adverse events (TEAEs) were reported in 31 (77.5%) pts. The most frequent (≥20% pts) Gr 3/4 TEAEs were thrombocytopenia in 12 pts (30%; grade 4 in 8 [20%]), neutropenia in 12 pts (30%; febrile neutropenia in 2 [5%]), anemia in 10 (25%) pts. Gr 3 infections were observed in 5 (12.5%) pts and fatigue in 5 (10%) pts. The main reason for treatment discontinuation was progressive disease (57.5%), other pts discontinued due to physician decision (5%), consent withdrawal (5%), and one pt due to adverse event. Twelve (30%) pts remain on treatment. At Cycle 1 Day 15, drug exposure and steady-state concentrations of KTX-1001 increased with dose. A dose-dependent reduction in H3K36me2, the primary PD marker of KTX-1001 activity, was observed in peripheral blood at Cycle 2 Day 1 and beyond, which plateaued above dose-level 4. Paired bone marrow samples further confirmed on-target PD effects, with a marked reduction in H3K36me2 levels in MM cells at Cycle 2 Day 1 with observed anti-MM effect of reduced proliferation of MM cells with concomitant increased proliferation in immune cells in pts achieving clinical benefit. ConclusionsKTX-1001 is a novel agent showing tolerable safety profile in RRMM and demonstrating promising single agent activity in heavily pretreated, triple class refractory RRMM including those with high-risk features. KTX is currently evaluated in ongoing study in combination with carfilzomib and the investigational CELMoD™ mezigdomide in t(4;14) RRMM pts.

Background: Cemsidomide (formerly CFT7455) is a novel, rationally designed, highly potent Ikaros Family Zinc Finger Protein 1/3 (IKZF1/3) MonoDACTM cereblon-based degrader. Cemsidomide has demonstrated best-in-class activity in multiple myeloma (MM) preclinical models and has also been shown to stimulate immune activation, providing combination rationale for various novel and standard of care therapies in MM. Methods: CFT7455-1101(NCT04756726) is an open-label, phase 1/2, multi-center, first-in-human study evaluating safety, efficacy, pharmacokinetics (PK), and pharmacodynamics (PD) of cemsidomide in patients (pts) with MM and non-Hodgkin's lymphoma who have relapsed from and/or are refractory to standard of care options. Eligible MM pts must have received lenalidomide, pomalidomide, a proteasome inhibitor, and an anti-CD38 antibody. The primary objective of the MM phase 1 portion of the study is to characterize the safety and tolerability of cemsidomide alone and in combination with dexamethasone (DEX) and to determine the maximum tolerated dose (MTD) and/or recommended doses for phase 2. Secondary objectives include assessments of antitumor activity according to the International Myeloma Working Group (IMWG) response criteria, PK, and PD. Dose escalation is guided by a Bayesian logistic regression model with an initial cohort size of 3-6 pts and a provision for additional pts to be enrolled in expansion cohorts at doses deemed safe. We report initial results from our ongoing cemsidomide plus DEX dose escalation arm. Results: As of July 3rd, 2024, 32 pts have been treated with cemsidomide at various doses plus DEX (20 or 40 mg weekly) in the ongoing dose escalation portion of the study. The median age was 64 (range 40-82) and pts had received a median of 6 prior lines of therapy (range 3-17). 21/32 (66%) of pts received prior treatment with a CAR-T or a bispecific antibody. 9/32 (28%) of pts had high-risk disease at screening and 6/32 (19%) of pts had extramedullary disease. Cemsidomide doses explored in dose-escalation and expansion cohorts included 50 µg MWF (n=6), 37.5 µg QD (n=12), 62.5 µg QD (n=10), and 75 µg QD (n=4), all on a 14 day on/14 day off dosing schedule. Systemic exposure of cemsidomide increased dose proportionally. At all dose levels, cemsidomide produced expected degradation of IKZF1 and IKZF3. To date only one dose-limiting toxicity has been observed (one pt in the 62.5 µg QD cohort experienced Grade 4 neutropenia lasting >7 days). 59% of pts experienced a grade ≥3 TEAE. Grade 3-4 TEAEs occurring in ≥10% of patients included neutropenia (34%), anemia (28%), infections (19%), lymphopenia (16%), and thrombocytopenia (13%). No pts experienced grade 3/4 fatigue, nausea, or vomiting. 5 pts have had treatment-related SAEs and 3 pts had an AE resulting in treatment discontinuation. As of the July 25th, 2024 efficacy cutoff, IMWG responses have been observed at all dose levels. The overall response rate among the 32 pts treated in dose escalation and expansion cohorts is 22% (1 sCR, 1 VGPR, and 5 PRs) with an additional 5 pts achieving minimal response (MR) for a clinical benefit rate of 38% (MR or better). To date, 2/4 (50%) pts in the 75 µg cohort have had a PR with expansion at 75 µg ongoing. Conclusions: Initial results from this ongoing phase 1 trial of cemsidomide in combination with DEX demonstrate encouraging efficacy and tolerability as an all-oral therapy in a heavily pre-treated MM population, with the majority of pts having received a CAR-T or bispecific antibody. As anticipated in MM, grade 3-4 toxicities consist largely of myelosuppression, which has been manageable. Given a favorable emerging safety profile and promising anti-myeloma activity, cemsidomide is potentially well suited to combine with other modalities, including proteosome inhibitors, monoclonal antibodies, antibody drug-conjugates and bispecific antibodies. Dose escalation will continue until an MTD and/or the recommended phase 2 doses are identified. Updated data will be presented at the conference.

Background: Despite recent major advances, multiple myeloma (MM) remains incurable using therapies that are currently available to patients. There are no available/approved targeted therapies for MM that allow for individualized therapeutic approaches to the disease. Fifteen to 20% of newly diagnosed MM patients have a translocation of chromosomes 4 and 14 [t(4;14)]. This translocation puts transcription of the gene encoding Multiple Myeloma SET domain-containing protein (MMSET or NSD2), a histone 3 lysine 36 methyltransferase, under the control of the IgH super enhancer. The super enhancer drives the overexpression of MMSET resulting in an abnormal histone code that promotes myelomagenesis. Presence of t(4;14) is associated with poor clinical prognosis (Caro Am Soc Clin Oncol Educ Book 2021). KTX-1001 is a first-in-class, selective and potent small molecule inhibitor of MMSET, and is the first investigational drug that targets the t(4;14) MM patient population. Methods: This Phase 1, first-in-human open-label study (NCT05651932) is designed to assess the safety, tolerability, and initial clinical activity of KTX-1001 in relapsed/refractory MM (RRMM) and has two parts: dose escalation (Part A) and dose expansion (Part B). In Part B, only t(4;14)+ MM patients will be evaluated in single agent and combination expansion cohorts. Patients with RRMM who have received ≥3 prior lines of therapy, including a proteasome inhibitor (PI), immunomodulatory drug (IMiD), and anti-CD38 antibody are eligible for the dose escalation part. The primary objective of the study is to determine a recommended phase 2 dose (RP2D) and schedule of KTX-1001. Secondary and exploratory objectives include pharmacokinetic (PK) and pharmacodynamic (PD) evaluation of KTX-1001, and assessment of preliminary efficacy. KTX-1001 is administered orally until disease progression, unacceptable toxicity, or patient withdrawal from the study. A Safety Review Committee (SRC) reviews all data prior to each dose escalation decision and on a regular basis. Results: As of June 14, 2024, 17 patients (pts) have been treated with KTX-1001 in Part A across 6 dose levels (SRC reviewed). Dose Level 7 has been reached with no dose limiting toxicities (DLTs). Ten of these patients are t(4;14) positive. Patients have received a median of 5 prior lines of therapy (range: 3-17), including 7 pts with prior BCMA CAR-T, 6 pts with prior BCMA bispecific and/or ADC, 5 pts with prior non-BCMA bispecific, and 12 pts with prior transplant. Patient demographics include a median age of 68 years (range: 50-83), 10 male/ 7 female, 13 white, 2 black or African American, 2 as other identified race, and 3 Hispanic or Latino pts. Six pts remain on treatment. KTX-1001 shows excellent tolerability to date, with treatment emergent AEs (TEAEs) (CTCAEv5.0) predominantly of grade 1 and 2 severity. Most frequently observed TEAEs suspected to be related to KTX-1001 include fatigue (35%), diarrhea (24%), and constipation (24%), for which no grade 3 or 4 events have been observed. Frequency and/or severity of TEAEs have not increased with escalating doses nor treatment duration, and no patients have discontinued due to an AE. Two heavily pre-treated patients [one known to be t(4;14)+] have demonstrated long-lasting stable disease and clinical benefit at 10 and 7 months respectively. Both patients have been intra-patient dose escalated. For PK and PD data collected to date, drug exposure and steady-state concentration of KTX-1001 (at C1D15, when steady state concentration has been reached) appear to be dose-proportional. PD data indicate a dose-dependent decrease in the H3K36me2 mark on treatment versus baseline across dose levels 1 through 6, suggesting that the RP2D may be reached by year end. Updated results will be presented at the congress. Conclusions: Dose escalation of KTX-1001 is ongoing with an excellent tolerability profile to date and demonstration of on-target pharmacodynamics that will inform the determination of the RP2D(s). These PD data support the targeted mechanism of action of KTX-1001 to selectively inhibit MMSET and break the t(4;14) histone code. Given KTX-1001's promising safety profile, single-agent and combination expansion cohorts with standard-of-care MM agents/classes will begin in 2025 to further optimize doses and provide proof of concept in Part B of the Phase 1 study.

Background: Despite the development and approval of effective therapies for multiple myeloma (MM), MM remains an incurable disease. Moreover, patients with high-risk cytogenetics, like translocation t(4;14), continue to have a poor prognosis compared to standard-risk patients. No novel agents have been approved specifically for this population. There remains an unmet need for precision therapies for MM that can target specific drivers of high-risk MM like t(4;14). Multiple myeloma SET domain-containing protein (MMSET) overexpression observed in 100% of patients with t(4;14) acts through the MMSET-H3K36me2 axis, which promotes malignant transformation through regulation of multiple oncogenic programs. KTX-1001, a methyl transferase inhibitor, is a novel, first-in-class, potent, oral, small molecule that inhibits MMSET and the methylation of lysine K36. KTX-1001 had favorable drug-like properties, demonstrated in vivo activity, and was well tolerated in non-clinical studies. Based on these data, KTX-1001 is now being studied in a Phase 1 dose escalation and expansion study in relapsed and refractory multiple myeloma (RRMM). Study Design and Methods: This multi-country, Phase 1, open-label study (NCT05651932) is designed to assess the safety, tolerability, and initial clinical activity of KTX-1001. The study will also examine the recommended phase 2 dose (RP2D), pharmacokinetics (PK) and pharmacodynamics (PD). Part A of this trial includes an accelerated titration, followed by 3+3 dose escalation with backfill of cohorts for dose optimization prior to moving to Part B, which is an expansion phase at the RP2D (please see Figure 1 for study design schematic). The expansion phase will only include patients with t(4;14). KTX-1001 will be administered orally daily and given until disease progression, unacceptable toxicity, or withdrawal from the study. Estimated enrollment for Parts A and B will be approximately 60 patients. The study will enroll patients with RRMM who have received ≥3 prior lines of therapy, including a proteasome inhibitor (PI), immunomodulatory drug (IMiD), and anti-CD38 antibody. Patients must have measurable disease, be ≥18 years of age, have an Eastern Cooperative Oncology Group score of ≤2, and adequate bone marrow, liver, and kidney function. Key exclusion criteria include history of or current plasma cell leukemia, active central nervous system (CNS) disease, or active unstable cardiovascular function. The primary endpoints of safety and tolerability include incidence of dose-limiting toxicity (DLTs), treatment-emergent adverse events (AEs), and treatment-related AEs. Secondary endpoints include plasma concentrations of KTX-1001 and efficacy outcomes such as objective response rate (ORR), duration of response (DOR), progression-free survival (PFS), and overall survival (OS). Exploratory biomarker and pharmacodynamic assessments will also be performed. The sample size was not determined by formal statistical methods but will be sufficient to provide preliminary information on safety, PK, PD, and efficacy. Statistical analyses will be primarily descriptive. Conclusion: This Phase 1 study will evaluate a potential treatment for RRMM utilizing KTX-1001, which is a novel, first-in-class, potent, oral small-molecule MMSET inhibitor. The study is open and actively enrolling patients at centers in the United States, Spain, France, and Canada.

Abstract Introduction: CFT7455 is a highly potent and novel Ikaros Family Zinc Finger Protein 1/3 (IKZF1/3) degrader. In xenograft models, CFT7455 has more potent IKZF1/3 degradation compared to other degraders. Early observations from the FIH clinical trial (NCT04756726) along with supporting translational studies are presented here. Methods: Pre-clinical studies comparing CFT7455 and CC-92480 in both in vitro and xenograft models were performed. The pre-clinical studies’ results coincided with observations from the on-going clinical trial. The clinical trial is an open-label, Phase 1/2, multi-center, FIH study in heavily pretreated relapsed/refractory (R/R) MM and non-Hodgkin’s lymphoma (NHL) patients evaluating safety, tolerability, and PK of CFT7455. Eligible MM patients are R/R to therapy and are not candidates for regimens known to provide clinical benefit. A starting dose of 50 μg QD 21 days on/7 days off (21/7) in 28-day cycles was administered. Results: CFT7455 and CC-92480 showed similar cereblon binding profiles and in vitro IKZF1/3 degradation kinetics, translating into sub-nanomolar GI50 values in proliferation assays across a panel of MM cell lines. In the NCI-H929 xenograft model, 100 μg/kg/day of CFT7455 resulted in durable tumor regressions, while 1000 μg/kg/day of CC-92480 gave tumor stasis. Similar results were seen in a systemic model of MM, MM1.S. Both compounds achieved >95% IKZF3 degradation in tumors 4h post dose. At 48h post dose, CFT7455 was more effective than CC-92480 in maintaining IKZF3 degradation (65% vs. 6% respectively). When levels of CFT7455 and CC-92480 in plasma and tumor were compared, CFT7455 concentrations were > DC80 in tumor 48h post dose, while CC-92480 levels were undetectable in tumor and plasma, demonstrating CFT7455 has longer exposure resulting in sustained IKZF1/3 degradation in pre-clinical models. In cohort A, 5 heavily pre-treated MM patients (pts) received single agent CFT7455. 4 pts have received at least 3 cycles, with 2 pts receiving 5 cycles. Neutropenia (grade 4) was observed in 3/5 pts without coincident fever or infection. Additionally, a 2-4 fold accumulation in plasma CFT7455 exposure at steady state was observed. Early pharmacodynamic (PD) data demonstrates deep persistent degradation of IKZF3 (~100%) and serum free light chain reduction (up to 72%) in response to treatment. Stable disease has been observed in 34 pts, suggesting clinical benefit. Conclusions: While CFT7455 showed clinical benefit at 50 ug with deep target degradation, neutropenia was dose limiting. PK/PD modeling suggests alternative dosing regimens may result in increased tolerability with preserved efficacy, and evaluation of them is underway. Updated results will be presented at the meeting. Citation Format: Sagar Lonial, Shambavi Richard, Jeffrey V Matous, Andrew J. Yee, Urvi Shah, Neha Mehta-Shah, Thomas Martin, Eli Muchtar, Sikander Ailawadhi, Paul G. Richardson, Manisha Bhutani, Samantha Perino, Jason Kirby, Roman V. Agafonov, Prasoon Chaturvedi, Bradley Class, Matthew Schnaderbeck, Michael R. Palmer, Cathleen Gorman, Oliver Schoenborn-Kellenberger, Amanda Hoerres, Stewart L. Fisher, Roy M. Pollock, Adam Crystal, Michelle Mahler, Jesus Bardeja. Pharmacokinetic (PK) profile of a novel IKZF1/3 degrader, CFT7455, enables significant potency advantage over other IKZF1/3 degraders in models of multiple myeloma (MM) and the results of the initial treatment cohort from a first-in-human (FIH) phase 1/2 study of CFT7455 in MM [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT186.

AbstractPreclinical data demonstrated that combining an anti–programmed cell death 1 (PD-1) inhibitor with a cyclin-dependent kinase 9 (CDK9) inhibitor provided enhanced antitumor activity with no significant toxicities, suggesting this combination may be a potential therapeutic option. The multicohort, phase 1 KEYNOTE-155 study evaluated the safety and antitumor activity of the PD-1 inhibitor pembrolizumab plus the CDK9 inhibitor dinaciclib in patients with relapsed or refractory (rr) chronic lymphocytic leukemia (CLL), diffuse large B-cell lymphoma (DLBCL) and multiple myeloma (MM). Patients enrolled were ≥18 years of age with a confirmed diagnosis of CLL, DLBCL, or MM. The study included 2 phases: a dose-evaluation phase to determine dose-limiting toxicities and a signal-detection phase. Patients received pembrolizumab 200 mg every 3 weeks plus dinaciclib 7 mg/m2 on day 1 and 10 mg/m2 on day 8 of cycle 1 and 14 mg/m2 on days 1 and 8 of cycles 2 and later. Primary endpoint was safety, and a key secondary endpoint was objective response rate (ORR). Seventy-two patients were enrolled and received ≥1 dose of study treatment (CLL, n = 17; DLBCL, n = 38; MM, n = 17). Pembrolizumab plus dinaciclib was generally well tolerated and produced no unexpected toxicities. The ORRs were 29.4% (5/17, rrCLL), 21.1% (8/38, rrDLBCL), and 0% (0/17, rrMM), respectively. At data cutoff, all 72 patients had discontinued treatment, 38 (52.8%) because of progressive disease. These findings demonstrate activity with combination pembrolizumab plus dinaciclib and suggest that a careful and comprehensive approach to explore anti–PD-1 and CDK9 inhibitor combinations is warranted. This trial was registered at www.clinicaltrials.gov as NCT02684617.