ABSTRACT
Cyclin dependent kinase 2 (CDK2) is responsible for enforcing progression through the G1-S phase transition. Mutations and alterations in the CDK2 signaling pathway are associated with various cancers, most commonly breast, ovarian, prostate, leukemia, and lymphoma. CDK2 inhibitors have shown promising preclinical and early clinical results, and this class of agents may be most effective against cancers with cyclin E overactivity. Common side effects observed include nausea, vomiting, diarrhea, anemia, and fatigue. This clinical review summarizes past and current CDK2 inhibitors in clinical trials.
INTRODUCTION
Cyclin dependent kinase 2 (CDK2) is responsible for enforcing progression through the cell cycle, specifically into the synthesis phase (Fig. 1).[1] Tumor suppressor protein Rb is responsible for regulating the transition between the G1 and S phases of the cell cycle. However, when Rb is phosphorylated, it de-represses E2F transcription factors that induce the transcription of genes important to the G1-S transition, such as cyclin E (CCNE), cyclin A (CCNA), cyclin B (CCNB), and many others. The cyclin E CDK2 complex phosphorylates Rb, which in turn, activates transcription factors overriding G1-S checkpoints and preventing apoptosis.[2–4] In the event of DNA damage, signal detection through ATM kinases induces phosphorylation and activation of CHK2.[2,5] Activation of CHK2 results in cascaded activation of p53, which functions to pause production in G1 to allow for cellular repairs. P53 activates expression of the cyclin-dependent kinase inhibitor (CKI) p21 gene, which inhibits the cyclin E/CDK2 complex. If the cyclin E/CDK2 complex reaches synthesis unharmed, the cyclin A replaces cyclin E to form the cyclin A/CDK2 complex and initiates the S-G2 transition through the phosphorylation of CDC6 and E2F1.[2–4] In addition, the cyclin E/CDK2 complex impacts MYC proteins through phosphorylation. The ultimate result of the interaction between the cyclin E/CDK2 complex and MYC is the prevention of cell senescence.[4]
Cyclin-dependent kinases (CDKs) and their subunits contribute to the regulation of the cell cycle. CDK3/cyclin C drives cell cycle entry from G0. The CDK4/6/cyclin D initiates phosphorylation of the retinoblastoma protein (pRb). In late G1, the CDK2/cyclin E complex completes the phosphorylation and inactivation of pRb, releasing E2F transcription factors. The G1/S transition then takes place. CDK4/6/cyclin D also leads to the sequestration of p21Cip1 and p27kip1, both of which inhibit CDK2, therefore fostering the activation of the CDK2/cyclin E complex. The CDK2/cyclin A complex regulates cell progression through the S phase, while the CDK1/cyclin A complex regulates progression through the G2 phase in preparation for mitosis. Mitosis is then initiated by the CDK1/cyclin B complex. (Adapted from Aleem and Arceci[1] as permitted by a CC-BY license).
Cyclin-dependent kinases (CDKs) and their subunits contribute to the regulation of the cell cycle. CDK3/cyclin C drives cell cycle entry from G0. The CDK4/6/cyclin D initiates phosphorylation of the retinoblastoma protein (pRb). In late G1, the CDK2/cyclin E complex completes the phosphorylation and inactivation of pRb, releasing E2F transcription factors. The G1/S transition then takes place. CDK4/6/cyclin D also leads to the sequestration of p21Cip1 and p27kip1, both of which inhibit CDK2, therefore fostering the activation of the CDK2/cyclin E complex. The CDK2/cyclin A complex regulates cell progression through the S phase, while the CDK1/cyclin A complex regulates progression through the G2 phase in preparation for mitosis. Mitosis is then initiated by the CDK1/cyclin B complex. (Adapted from Aleem and Arceci[1] as permitted by a CC-BY license).
Signaling through CDK2 alone can induce oncogenesis when accompanied by alterations in other cyclin dependent kinases (CDKs), cyclins, and more.[6] In most cancers in which CDK2 signaling contributes to oncogenesis, the CDK2 gene is not mutated but instead its protein signaling activity is often increased due to interactions with cyclin E or cyclin A.[6] High cyclin E activity has been observed in lung, colorectal, gastric, and bone cancers, and abnormal CDK2 activity can be found in any cancer, including commonly in breast cancer, leukemia, lymphoma, and melanoma.[3,7,8] CDK2 interactions can depend on separate lineage-specific factors.[5,8] In cancers with abnormal CDK2 activity or high levels of cyclin E, genomic instability can occur.[6] Overactivation of CDK2 leads to excessive phosphorylation of Rb, resulting in a premature and unregulated G1-S transition.[3] Unregulated G1-S transition can prevent cells from repairing damaged DNA before S phase, leading to mutations occurring in synthesis.[9] In addition, increased stress on DNA replication can cause deletions and overall underreplication. The CDK2/cyclin E complex also inhibits complex-Cdh1, which is responsible for promoting anaphase and causes polyploidy through inaccurate segregation of chromosomes. CDK2 even mediates the phosphorylation of estrogen, progesterone, and androgen receptors, commonly resulting in hormone-dependent breast and prostate cancers.[6]
Preclinical studies of CDK2 inhibitors have shown early promising results. Mice with a CDK2 reliant leukemia xenograft treated with CDK2 inhibitor homoharringtonine (HHT) survived significantly longer than xenograft mice with a vehicle injection.[10] In three breast cancer cell lines, CDK2/1 inhibitors NU2058 and NU6102 reduced phosphorylation of Rb and led to G1 backup or cell arrest.[11] In human ovarian and gastric cancer cell lines, INX-315 inhibited Rb phosphorylation and promoted G1 cell arrest.[12] CDK2 inhibitor ARTS-021 has displayed strong inhibition of CCNE1-amplified Rb phosphorylation in patient-derived xenografts.[13] In the multiple myeloma cell line RPMI-8226, treatment with CDK2/7/9 inhibitor SNS-032 at 300 nM for 6 hours was sufficient to achieve apoptosis and inhibition of CDKs 2, 7, and 9 in substrate signaling molecules.[14] In chronic lymphocytic leukemia cells, fadraciclib depleted anti-apoptotic protein and synergized with Bcl-2 antagonist venetoclax.[15]
This clinical review aims to provide a concise compilation of the clinical trials of CDK2 inhibitors currently or previously in development (Tables 1 and 2). The information in this review was collected from publicly available abstracts presented at oncology conferences, published manuscripts, and clinical trials registered on clinicaltrials.gov.
METHODOLOGY
A systematic search was conducted and was completed on Sep 20, 2024. The search was limited to abstracts and articles published in English, and no date limiters were applied. Abstracts and articles were eligible for inclusion if they described the design and/or results of a clinical trial of CDK2-selective inhibitor. Search terms on clinicaltrials.gov included “CDK2” and “cyclin dependent kinase 2.” Filters used were “interventional.” For trials that were completed, additional searches for associated articles were performed on Google to find published data, if available.
CDK2-specific Inhibitors
BLU-222
BLU-222 (Blueprint Medicines, Cambridge, MA) is a selective CDK2 inhibitor currently in development, which works to impair cell growth that has been amplified by cyclin E1 (CCNE1). Patients who qualified for this study were adults with nonresectable tumors that had progressed following standard of care and were either CCNE1-amplified solid tumor cancers or ER+/HER2− breast cancer. CCNE1 levels were monitored while on treatment. Sixty-four patients were enrolled into the trial, including 53 patients in the monotherapy cohorts at doses ranging from 50 mg twice a day (BID) to 800 mg BID, as well as 11 patients in the combination cohort of BLU 100 to 200 mg BID + ribociclib 400 mg + fulvestrant 500 mg. The most common cancers enrolled in the monotherapy cohorts were breast (32%) and ovarian (21%) cancer. The most common treatment-emergent adverse events (AEs) included gastrointestinal events (nausea, diarrhea, vomiting), fatigue, photophobia, and hypokalemia. Two dose-limiting toxicities (DLTs) were reported, including grade 3 nausea (n = 1) at 800 mg and grade 3 blurred vision (n = 1) at 600 mg. The maximum tolerated dose had not yet been reached at the data cutoff. The combination with ribociclib and fulvestrant revealed no additional safety concerns. A partial response with monotherapy was observed in a patient with estrogen receptor positive (ER+)/ human epidermal growth factor receptor-2–negative (HER2−) metastatic breast cancer (mBC) who had previously received five lines of therapy including palbociclib, abemaciclib, and capecitabine. The estimated average half-life of BLU-222 was 12 hours, and plasma concentration of BLU-222 increased proportionally. Preliminary evidence of cell cycle pathway modulation was observed. At the highest dose levels, reductions in serum TK1 activity proliferation marker and downstream target of the phosphorylation of the retinoblastoma protein (pRb)-E2F pathway was observed. In addition, reductions in pRb were observed in two patients treated at 400 mg BID, including one patient with the confirmed partial response.[16,17]
PF-07104091
PF-07104091[18] (Pfizer, New York City, NY) is a selective CDK2 inhibitor currently in development. The phase 1 clinical trial investigated PF-07104091 as monotherapy. The trial enrolled 35 patients, all of whom had advanced or metastatic small-cell lung, breast, or ovarian cancers. Twenty-nine of the 35 patients had hormone receptor positive (HR+)/HER2− advanced/mBC. Among these 29 patients with mBC, all had received prior CDK4/6 inhibitor treatment, 25 (86.2%) had prior fulvestrant, and 21 (72.4%) had prior chemotherapy. The patients had a median age of 62 (range 32–80 years). PF-07104091 was administered at doses of 75 to 500 mg per os BID in 28-day cycles. Thirty-four of the 35 patients experienced treatment-emergent adverse events (TEAEs). The most frequently occurring TEAEs (all were ≤G3) included nausea (77.1%; 14.3% G3), diarrhea (48.6%; 8.6% G3), vomiting (48.6%; 2.9% G3), fatigue (45.7%; 20.0% G3), and anemia (45.7%; 8.6% G3). Two patients had TEAEs ≥ G4, one with neutropenia (G4) and one with a G5 AE unrelated to treatment. Five patients experienced DLT, including one patient at 300 mg BID with G3 fatigue, one patient at 375 mg BID with G3 nausea, one patient at 375 mg BID with G3 nausea and G3 anorexia, one patient at 500 mg BID with G3 fatigue, and one patient at 500 mg BID with G3 nausea. PF-07104091 was rapidly absorbed, with the median time to maximum concentration (Tmax) being 0.5 to 4 hours. The mean effective half-life was approximately 2 to 3 hours. Steady-state PF-07104091 plasma exposure proportionally increased with the given dose. The maximum tolerated dose (MTD) and monotherapy recommended dose for expansion were identified to be 300 mg BID. The trial showed an early trend of a decrease in circulating tumor DNA levels between cycle 1 day 1 and cycle 1 day 15 for response evaluable patients treated at ≥150 mg BID. Sixteen patients with mBC were identified as response evaluable. Of the 16, three had objective partial responses, and six had stable disease. The disease control rate was 61.5% in patients with mBC. In summary, PF-07104091 was generally tolerable, with promising early results in patients with HR+/HER2− mBC who previously progressed on CDK4/6 inhibitors. Dose expansions are ongoing for patients with ovarian cancer (monotherapy) and breast cancer (combination with fulvestrant).[18]
CDK2/4/6 Inhibitors
NUV-422
NUV-422 (Nuvation Bio, New York City, NY) is a selective CDK2/4/6 inhibitor currently under investigation in a phase 1 trial. The trial employs a 3 + 3 dose escalation design with the goal of evaluating safety and tolerability, as well as determining a recommended phase 2 dose. Nineteen patients with advanced solid tumors, including high-grade gliomas, HR+/HER2− breast cancer, and prostate cancer were enrolled.[19] During the dose escalation portion of the trial, uveitis emerged in multiple patients receiving the treatment. The study sponsor announced in a press release that in order to assess this AE with both investigators and uveitis experts, Nuvation Bio would pause new patient enrollment, although current patients would be allowed to continue treatment. Further clinical development of NUV-422 was later ultimately discontinued by Nuvation Bio.[20]
Other CDK2 Inhibitors
R547
R547 (Hoffmann-La Roche, Basel, Switzerland) is a selective CDK1/2/4 inhibitor. In the phase 1a clinical trial, R547 was given in 90- or 180-minute infusions of 8.6 to 195 mg/m2 on days 1 and 8 of a 21-day cycle. Forty-one patients were enrolled (31 patients with the 90-minute infusion and 10 patients with the 180-minute infusion), with a mean age of 53.4 years (range 20–81). Four DLTs were observed at the 195 mg/m2 dose, including grade 3 somnolence (n = 1), grade 3 confusion (n = 1), and grade 3 fatigue (n = 1) in the 90-minute infusion schedule and prolonged grade 3 pruritus (n = 1) in the 180-minute infusion schedule. Patients experienced AEs in both groups, the most common of which included nausea (54%), fatigue (34%), emesis (34%), headache (34%), and hypotension (32%). All of the AEs were grade 1 or 2 except for four patients with grade 3 fatigue and one patient with grade 3 nausea. The mean area under the curve (AUC) for 20 patients receiving ≥155 mg/m2 exceeded exposures efficacious in xenograft studies. At equivalent doses, the 180-minute infusion schedule produced equivalent AUC but a 30% reduction of Cmax. Twenty-one patients had sufficient samples available for analysis of pharmacodynamics, which demonstrated an exposure-dependent decrease in the pRb/total Rb ratio 1.5 to 24 hours post-infusion. One patient with squamous cell carcinoma had tumor regression, and eight additional patients continued treatment for at least four cycles. Treatment was determined to be tolerable at doses of 155 mg/m2 on days 1 and 8 (21-day cycle) for both the 90-minute and 180-minute infusion schedules.[21]
SNS-032
SNS-032 (Sunesis Pharmaceuticals, San Francisco, CA) is a CDK2/7/9 inhibitor under investigation to target B-cell malignancies resistant to apoptosis, including chronic lymphocytic leukemia (CLL) and multiple myeloma. The phase 1 dose escalation study enrolled patients with advanced CLL and multiple myeloma to assess safety and tolerability. SNS-032 was administered as a 5-minute loading dose, followed by a 6-hour maintenance infusion weekly for 3 weeks for each 4-week cycle. Eligible patients with CLL had measurable relapse after one or more rounds of prior treatment. Patients with multiple myeloma were required to have received two or more prior treatments including (1) thalidomide, bortezomib, or lenalidomide and (2) autologous stem-cell transplantation. Nineteen patients with CLL and 18 patients with multiple myeloma were enrolled, with a median age of 63 for CLL and 61 for multiple myeloma. Two of the three patients with CLL treated at 100 mg/m2 experienced a DLT of grade 3 tumor lysis syndrome. Tumor lysis syndrome was also observed in four patients with CLL treated at 75 mg/m2, of which one was grade 3. The MTD for patients with CLL was 75 mg/m2. No MTD was determined nor were DLTs observed among patients with multiple myeloma. Generally similar proportions of patients with CLL (74%) versus multiple myeloma (78%) experienced grade 3 and grade 4 AEs. However, grade 3 and 4 AEs that were more common in patients with multiple myeloma included neutropenia, thrombocytopenia, and anemia. The most common grade 1 and grade 2 AEs included nausea, vomiting, constipation, and diarrhea. One patient with CLL had more than 50% reduction in measurable disease without improvement in hematologic parameters. Another patient with low tumor burden had stable disease for four cycles. Two patients with multiple myeloma had stable disease, and one had normalization of spleen size with treatment. Target SNS-032 concentrations were achieved and exceeded at the 50 mg/m2 dose level (cohort 4) with maximum plasma concentration at 6 hours of 142.7 ng/mL. Greater than dose-proportional increase in exposure was observed in both patients with CLL and multiple myeloma. The observed half-life was between 7.39 and 15.95 hours across all dose levels. The half-life at the MTD (75 mg/m2) was 9.02 hours. Inhibition of CDK9 and CDK7 was demonstrated by decrease in phosphorylation of Ser5 and Ser2 in the C-terminal domain of RNA Pol II in patients receiving a dose of 75 mg/m2. Inhibition was seen as early as 2 hours following the start of infusion and was pronounced after 6 hours, with a return to baseline after 24 hours. A more potent half maximal inhibitory concentration for CDK9 was shown when compared with that for CDK7, as inhibition of Ser2 (64%) was more significant than for Ser5 (35%) 6 hours after infusion. Additional pharmacodynamic properties observed included down-regulation of Mcl-1 protein level, modest down-regulation of XIAP protein level, no significant change in Bcl-2 protein level, and evidence of apoptosis as detected by PARP cleavage.[22]
Fadraciclib
Fadraciclib (formerly CYC065) (Cyclacel, Berkely Heights, NJ) is a CDK2/9 inhibitor that was initially investigated with an intravenous formulation in a trial that was never published. However, at a later time an oral formulation was developed, and the phase 1 trial of oral formulation fadraciclib was presented at ASCO 2024. Forty-five patients were treated at various doses and schedules, including (1) 50 to 150 mg given 3 to 5 days per week for 3 to 4 of 4 weeks, and (2) 125 mg daily. DLTs observed included grade 3 hyperglycemia (one of two patients treated at dose level 6 and two of six patients treated at dose level 6a) and nausea (one of two patients treated at dose level 6). The MTD for the bid dosing schedule was determined to be 100 mg BID, Monday–Friday, 4 of 4 weeks. Pharmacokinetics revealed dose-dependent exposure. At DL5 and above, plasma concentration exceeded the target concentration identified in CDK2 and CDK9 target engagement studies. Pharmacodynamic analysis demonstrated suppression of multiple target genes. Two partial responses were observed, in patients with cutaneous T cell lymphoma and angioimmunoblastic T cell lymphoma. In addition, a patient with squamous non–small-cell lung cancer achieved a 22% decrease.[23]
Ongoing Clinical Trials of CDK2 Inhibitors Without Published Results
Additional clinical trials of CDK2 inhibitors are ongoing that have not yet published even preliminary results, and several representative examples are summarized in Table 2. These ongoing trials are enrolling a wide range of tumor types, including not only solid tumor cancers, but also lymphomas, acute myelogenous leukemia (AML), myelodysplastic syndrome (MDS), and CLL.
Discussion
Selective CDK2 inhibitors have entered clinical trials for patients with both hematologic and solid tumor cancers because of promising results in preclinical studies. Six selective CDK2 inhibitors have reported results in clinical trials and have most commonly enrolled patients with HR+/HER2− breast cancer, CLL, multiple myeloma, ovarian cancer, and high-grade gliomas. To date, R547, PF-07104091, BLU-222, and SNS-032 have shown evidence of antitumor activity. Of the 41 patients with advanced solid tumors treated with R547, one had tumor regression. In the trial of PF-07104091, of 29 patients with HR+/HER2− metastatic breast cancer, three had a partial response and six had stable disease, with a disease control rate of 61.5%. Among the 27 patients with nonresectable CCNE1-amplified or ER+/HER2− breast cancer treated with BLU-222, one patient had a confirmed partial response. In the trial of SNS-032, one of the 19 patients with CLL achieved a greater than 50% reduction in measurable disease, and another patient with CLL had stable disease for four cycles. Among the 18 patients with multiple myeloma, two had stable disease.
CDK2 inhibitors have been formulated for either oral or intravenous administration. Among these six agents, BLU-222, fadraciclib, PF-07104091, and NUV-422 were all administered orally, in contrast to SNS-032 and R547, which were administered intravenously. The half-lives reported for these agents varied, including 2 to 3 hours for PF-07104091, 9.02 hours for SNS-032, and 12 hours for BLU-222. Pharmacokinetics analysis results have not yet been reported for the other two agents.
Overall, CDK2 inhibitors have demonstrated a tolerable safety profile. The DLTs observed with CDK2 inhibitors to date include nausea, fatigue, blurred vision, anorexia, confusion, somnolence, and pruritus. The most common AEs reported were nausea (26%–77%), vomiting (11%–49%), diarrhea (22%–49%), and fatigue (15%–46%). The types of observed AEs with the most selective CDK2 inhibitors, BLU-222 and PF-0704091, have been similar to the less selective CDK2 inhibitors. However, on the clinical trial of BLU-222, the frequency of these AEs trended lower compared with the other agents. Of note, with the other inhibitor that exclusively targeted CDK2, PF-07104091, the frequency of treatment-related AEs trended higher compared with the other trials and with a trend of higher-grade severity as well. To date, a higher percentage of patients treated with PF-07104091 have achieved objective responses, so the trend of greater toxicity may simply reflect greater dose intensity among the patients treated so far. With the exception of NUV-422, on which enrollment was held due to the emergence of uveitis, the CDK2 inhibitors were found to have been generally tolerable, with similar side effects.
Because the response rate among patients treated with selective CDK2 inhibitors has been relatively low, a selective biomarker could be useful in identifying patients more likely to benefit from this class of drug. Several biomarkers have been investigated as potential surrogate indicators of altered CDK2 activity. CCNE1 is a gene that regulates CDK2, the overexpressed protein in many tumors that is targeted by these drugs, making CCNE1 a promising biomarker. In a preclinical study of a CCNE1-amplified ovarian cancer mouse model, CCNE1 copy number increase was a strong predictor of response to CDK2 inhibition across tumor types.[24] Other potential biomarkers for future investigation include (1) cyclin E1/2 overexpression, which is common in inflammatory breast cancer and high-grade serous ovarian cancer; (2) Cyclin E1 mutations, present in about 20% of platinum-resistant high-grade ovarian cancer; (3) CDK2 overexpression, which is common in glioblastoma, prostate cancer, and B-cell lymphoma; (4) FBXW7 loss, which is associated with CDK2 alterations in colon and breast cancer; (5) PP2A-B56 amplification, which is associated with altered CDK2 activity in cervical cancer; and (6) USP28 overexpression, which is associated with altered CDK2 activity in high-grade serous ovarian cancer.[6] In preclinical studies of R547, 26 potential biomarkers were identified and tested in patient blood samples using quantitative real-time PCR analysis, and based on those results, eight genes (FLJ44342, CD86, EGR1, MKI67, CCNB1, JUN, HEXIM1, and PFAAP5) were selected as pharmacodynamic biomarkers for phase 2 trials.[25] To date, CDK2-specific inhibitors like BLU-222 and PF-07104091 have demonstrated a trend of less toxicity than agents that inhibit multiple CDKs, as might be expected. Clinical efficacy with CDK2-specific inhibitors also appears to be better, with objective responses observed with monotherapy. Because of the tolerable side-effect profile of CDK2-specific inhibitors as monotherapy and because CDK2 signaling is a potential mechanism of resistance to CDK4/6 inhibition, combination with CDK4/6 inhibitors is ongoing and also planned for future trials.
CDK2 inhibitors are suspected to have two main mechanisms of resistance. In preclinical studies, resistance to CDK2 inhibitors was demonstrated to occur because of upregulation of CKD2 target protein. Preexisting cellular polyploidy was found to cause resistance as well.[26] A number of combination regimens with CDK2 inhibitors have been proposed to overcome resistance. For example, among patients treated with CDK4/6 inhibitors for breast cancer, CCNE1 may mediate resistance. Thus, pairing an inhibitor designed to exclusively target CDK2, with a CDK4/6 inhibitor, could be promising. Preclinical studies have also suggested that CDK2 inhibitors could be effective in targeting ovarian cancers when paired with cytotoxic chemotherapy or PARP inhibitors. The combinations of BLU-222 with carboplatin, BLU-222 with olaparib, and BLU-222 with gemcitabine all induced tumor regression in mouse models that was sustained even after treatment cessation.[24] BLU-222 is being investigated in an ongoing phase 1 trial with additional arms exploring combinations with carboplatin, ribociclib, and fulvestrant.[27] Separately, PF-07104091 is currently undergoing investigation in various drug combinations, specifically focusing on patients with breast cancer, including combinations with fulvestrant, letrozole, and CDK4 inhibitor PF-07220060.[26]
CONCLUSION
In summary, CDK2 inhibitors are a promising class of drug that has shown early antitumor activity in both solid tumor cancers and hematological malignancy. Additional studies are ongoing to further investigate safety and efficacy in various tumor types, as monotherapy and in combination with other agents.
References
Author notes
Source of support: None. Conflict of interest: Gerald S. Falchook reports royalties from Wolters Kluwer (2014-present); advisory role for AbbVie (2022), Jubilant (2022), BostonGene (2022), Teon (2022), Merck (2022), Sanofi (2023), and BridgeBio (2023); speakers honorarium for CME from Clinical Care Options (2024); travel expenses from Sarah Cannon Research Institute (employer, at least once yearly), Amgen (2022), Synthorx/Sanofi (2022), GSK (2023), Cyteir (2023); research funding (to institution) from Abbisko, ABL Bio, ADC Therapeutics, Accutar, Agenus, Aileron, Amgen, Eli Lilly, Artios, AstraZeneca, Bayer, BeiGene, Bioatla, Bioinvent, Biomea Fusion, Bicycle, Black Diamond, Boehringer Ingelheim, Centessa, Conjupro, Cyteir, Daiichi, Eikon, Eli Lilly, Epizyme, Erasca, Exelixis, Freenome, Fujifilm, GlaxoSmithKline, Harbour BioMed, Hutchison MediPharma, IGM Biosciences, IDEAYA, Immunitas, ImmunoGen/MacroGenics, Jacobio, Jazz, Jounce, Jubilant, Kineta, Kura, Loxo/Bayer, Merck, Metabomed, Mirati, Molecular Templates, Navire/BridgeBio, NGM Bio, NiKang, Novartis, Nuvectis, Oncorus, Phanes, Poseida, Prelude, PureTech, Pyramid, Pyxis, RasCal, Regeneron, Relay, Rgenix, Ribon, Roche, Samumed, Sapience, Sarah Cannon Development Innovations, Seagen, Silicon/Stingthera, Simcha, Sirnaomics, Synthorx/Sanofi, Takeda, Tallac, Tango, Tarus, Tarveda, Teneobio, Tesaro, Turning Point, Xencor, and Zhuhai Yufan. The remaining authors have nothing to disclose.