Background: Despite advances in the treatment of early triple-negative breast cancer (TNBC), patients with residual invasive disease after neoadjuvant therapy have a high risk of disease recurrence and worse survival outcomes than those who have pathological complete response (pCR). Improving outcomes in early TNBC remains an unmet need requiring new adjuvant treatment approaches. Datopotamab deruxtecan (Dato-DXd) is an antibody–drug conjugate comprising a humanized anti-trophoblast cell-surface antigen 2 immunoglobulin G1 (IgG1) monoclonal antibody attached via a plasma-stable, cleavable linker to a potent topoisomerase I inhibitor payload, with activity observed in advanced TNBC. Objectives: TROPION-Breast03 is an ongoing phase III study evaluating the efficacy and safety of Dato-DXd alone or combined with durvalumab versus standard-of-care therapy as adjuvant treatment in patients with stage I–III TNBC with residual invasive disease at surgical resection following neoadjuvant treatment. Methods and design: Eligible patients, aged ⩾18 years, will be randomized in a 2:1:2 ratio to receive Dato-DXd [6 mg/kg intravenously (IV) every 3 weeks (Q3W); eight cycles] and durvalumab (1120 mg IV Q3W; nine cycles), Dato-DXd monotherapy (6 mg/kg IV Q3W), or investigator’s choice of therapy (ICT; capecitabine, pembrolizumab, or capecitabine and pembrolizumab). The primary endpoint is invasive disease-free survival (iDFS) for Dato-DXd and durvalumab versus ICT. Key secondary endpoints include safety, distant disease-free survival, and overall survival for Dato-DXd and durvalumab versus ICT and iDFS for Dato-DXd monotherapy versus ICT. Ethics: TROPION-Breast03 will be approved by the independent ethics committees or institutional review boards at each study site. All study participants will provide written informed consent. Discussion: TROPION-Breast03 will help define the potential role of Dato-DXd in the treatment of patients with early-stage TNBC who do not have pCR after neoadjuvant therapy. Trial registration: ClinicalTrials.gov identifier: NCT05629585 (registration date: 29 November 2022).

The therapeutic potential of targeting PI3K/AKT/PTEN signalling in B-cell malignancies remains attractive. Whilst PI3K-α/δ inhibitors demonstrate clinical benefit in certain B-cell lymphomas, PI3K signalling inhibitors have been inadequate in relapsed/refractory diffuse large B-cell lymphoma (DLBCL) in part, due to treatment related toxicities. Clinically, AKT inhibitors exhibit a differentiated tolerability profile offering an alternative approach for treating patients with B-cell malignancies. To explore how AKT inhibition complements other potential therapeutics in the treatment of DLBCL patients, an in vitro combination screen was conducted across a panel of DLCBL cell lines. The AKT inhibitor, capivasertib, in combination with the BCL-2 inhibitor, venetoclax, produced notable therapeutic benefit in preclinical models of DLBCL. Capivasertib and venetoclax rapidly induced caspase and PARP cleavage in GCB-DLBCL PTEN wildtype cell lines and those harbouring PTEN mutations or reduced PTEN protein, driving prolonged tumour growth inhibition in DLBCL cell line and patient derived xenograft lymphoma models. The addition of the rituximab further deepened the durability of capivasertib and venetoclax responses in a RCHOP refractory DLBCL in vivo models. These findings provide preclinical evidence for the rational treatment combination of AKT and BCL-2 inhibitors using capivasertib and venetoclax respectively alongside anti-CD20 antibody supplementation for treatment of patients with DLBCL.

PURPOSE Homologous recombination repair gene mutations (HRRm) are common in urothelial carcinoma (UC), rendering tumor cells sensitive to poly (ADP-ribose) polymerase (PARP) inhibition. We assessed efficacy and safety of durvalumab (anti–programmed cell death ligand-1) plus olaparib (PARP inhibitor) in patients with metastatic UC (mUC). METHODS This randomized, multicenter, double-blind, phase II trial enrolled untreated, platinum-ineligible patients with mUC. Patients (N = 154) were randomly assigned 1:1 to receive durvalumab (1,500 mg intravenously once every 4 weeks) plus olaparib (300 mg orally, twice daily) or durvalumab plus placebo. The primary end point was progression-free survival (PFS) assessed by investigators per RECIST version 1.1. Secondary end points included overall survival in all patients and PFS in patients with HRRm. RESULTS Overall, median PFS was 4.2 months (95% CI, 3.6 to 5.6) for durvalumab plus olaparib and 3.5 months (95% CI, 1.9 to 5.1) for durvalumab plus placebo (hazard ratio [HR], 0.94; 95% CI, 0.64 to 1.39; log-rank P value, .789). Median overall survival was 10.2 months (95% CI, 7.0 to 13.9) and 10.7 months (95% CI, 7.2 to 17.3), respectively (HR, 1.07; 95% CI, 0.72 to 1.61). In the 20% of patients with HRRm, median PFS was 5.6 months (95% CI, 1.9 to 8.1) and 1.8 months (95% CI, 1.7 to 2.2), respectively (HR, 0.18; 95% CI, 0.06 to 0.47). Treatment-related grade 3 or 4 adverse events occurred in 18% and 9% of patients, respectively. CONCLUSION Adding olaparib to durvalumab did not improve survival outcomes in an unselected mUC population. Efficacy outcomes with durvalumab were similar to those reported for other anti–programmed cell death-1/programmed cell death ligand-1 agents. However, the results of secondary analyses suggest a potential role for PARP inhibition in patients with UC harboring HRRm.

Supplementary Tables 1-3 and Figure 1-7. Supp Table 1 Summary of cell line origins and verification. Supp Table 2 Summary of antibodies used in all experimental analysis Supp Fig 1 AZD8186 inhibits PI3K pathway in PTEN null but not PTEN WT PIKC3A MT cells Supp Fig 2 AZD8186 inhibits LPA, EGF and rac dependent Ser473 AKT phosphorylation in serum starved prostate and breast cancer cells Supp Fig 3 Western blot analysis of showing induction of FOXO3a association with the chromatin fraction following treatment with AZD8186 Supp Fig 4 AZD8186 inhibits proliferation in a subset of cancer cell lines Supp Table 3 GI50 of all cell lines showing sensitivity to AZD8186 Supp Fig 5 Western blot protein analysis of PTEN status across a panel of breast and prostate cell lines Supp Fig 6 Pathway biomarker suppression in PC3 and HID28 tumours Supp Fig 7 AZD8186 selectively suppresses pathway biomarkers in tumour versus lung

BACKGROUND:Concurrent chemoradiotherapy has been the standard of care for locally advanced cervical cancer for over 20 years; however, 30-40% of treated patients have recurrence or progression within 5 years. Immune checkpoint inhibition has improved outcomes for patients with PD-L1 positive metastatic or recurrent cervical cancer. We assessed the benefit of adding durvalumab, a PD-L1 antibody, with and following chemoradiotherapy for locally advanced cervical cancer. METHODS:The CALLA randomised, double-blind, phase 3 trial included 105 hospitals across 15 countries. Patients aged at least 18 years with previously untreated locally advanced cervical cancer (adenocarcinoma, squamous, or adenosquamous; International Federation of Gynaecology and Obstetrics [FIGO] 2009 stage IB2-IIB lymph node positive, stage ≥III any lymph node status) and WHO or Eastern Cooperative Oncology Group performance status of 0 or 1 were randomly assigned (1:1) through an interactive web response system using a permuted block size of 4 to receive durvalumab (1500 mg intravenously once every 4 weeks) or placebo with and following chemoradiotherapy, for up to 24 cycles. Chemoradiotherapy included 45 Gy external beam radiotherapy at 5 fractions per week concurrent with intravenous cisplatin (40 mg/m2) or carboplatin (area under the concentration-time curve 2) once weekly for 5 weeks, followed by image-guided brachytherapy (high-dose rate, 27·5-30 Gy or low-dose/pulse-dose rate, 35-40 Gy). Randomisation was stratified by disease stage status (FIGO stage and node status) and geographical region. Chemoradiotherapy quality was continuously reviewed. The primary endpoint was progression-free survival, assessed by the investigator using Response Evaluation Criteria in Solid Tumors, version 1.1, in the intention-to-treat population. Safety was assessed in patients who received at least one dose of study treatment. This study is registered with ClinicalTrials.gov, NCT03830866. FINDINGS:Between Feb 15, 2019, and Dec 10, 2020, 770 women were randomly assigned (385 to durvalumab and 385 to placebo; median age 49 years [IQR 41-57]). Median follow-up was 18·5 months (IQR 13·2-21·5) in the durvalumab group and 18·4 months (13·2-23·7) in the placebo group. At data cutoff, median progression-free survival had not been reached (95% CI not reached-not reached) for either group (HR 0·84; 95% CI 0·65-1·08; p=0·17); 12-month progression-free survival was 76·0% (71·3-80·0) with durvalumab and 73·3% (68·4-77·5) with placebo. The most frequently reported grade 3-4 adverse events in both groups were anaemia (76 [20%] of 385 in the durvalumab group vs 56 [15%] of 384 in the placebo group) and decreased white blood cells (39 [10%] vs 49 [13%]). Serious adverse events occurred for 106 (28%) patients who received durvalumab and 89 (23%) patients who received placebo. There were five treatment-related deaths in the durvalumab group (one case each of urinary tract infection, blood loss anaemia, and pulmonary embolism related to chemoradiotherapy only; one case of endocrine disorder related to durvalumab only; and one case of sepsis related to both durvalumab and chemoradiotherapy). There was one treatment-related death in the placebo group (pneumonia related to chemoradiotherapy). INTERPRETATION:Durvalumab concurrent with chemoradiotherapy was well tolerated in participants with locally advanced cervical cancer, however it did not significantly improve progression-free survival in a biomarker unselected, all-comers population. Concurrent durvalumab plus chemoradiotherapy warrants further exploration in patients with high tumoral PD-L1 expression. Rigorous monitoring ensured high chemoradiotherapy compliance with advanced technology and allowed patients to receive optimal care. FUNDING:AstraZeneca.

Supplementary Materials text. Supplementary text to support supplementary data.

Spleen tyrosine kinase (SYK) is a non-receptor cytoplasmic kinase. Due to its pivotal role in B cell receptor and Fc-receptor signalling, inhibition of SYK has been a target of interest in a variety of diseases. Herein, we report the use of structure-based drug design to discover a series of potent macrocyclic inhibitors of SYK, with excellent kinome selectivity and in vitro metabolic stability. We were able to remove hERG inhibition through the optimization of physical properties, and utilized a pro-drug strategy to address permeability challenges.

ObjectivesIn locally-advanced cervical cancer (LACC), platinum-based chemoradiotherapy (CRT) has been the standard- of-care treatment for >20 years. CALLA is the first global Phase 3 study evaluating immune checkpoint inhibition (durvalumab) versus placebo in combination with and following CRT in LACC (NCT03830866).MethodsNewly-diagnosed, untreated patients with LACC (FIGO 2009 stages IB2-IIB node positive, IIIA-IVA with any node status) were randomized 1:1 to durvalumab (1500 mg IV) or placebo Q4W, for a total of up to 24 months, in combination with and following CRT. CRT comprised concurrent weekly IV cisplatin with EBRT and brachytherapy. RT quality was monitored, with variations evaluated for clinical significance. The primary endpoint is PFS; secondary endpoints include OS, objective response rate, local/distant disease progression incidence, and safety.Results770 patients were randomized (N=385 per arm) at 120 sites in 15 countries. Median age was 49 years; median follow-up was 18.5 months. Durvalumab+CRT did not show a statistically significant improvement in PFS vs placebo+CRT (HR 0.84 [95% CI, 0.65–1.08]; P=0.174); there was no detriment to OS, although data were immature and not formally tested. Adverse events of grade 3–4 occurred in 51.7% and 51.0% of patients in the durvalumab+CRT and placebo+CRT arms, respectively; 12.5% and 9.6% of patients discontinued treatment due to AEs possibly related to study drug.ConclusionsDurvalumab in combination with and following CRT did not significantly improve PFS in patients with LACC. Safety of durvalumab+CRT was generally comparable to CRT alone, with no new or unexpected toxicity. Funding: AstraZeneca.

Background: Chemotherapy, together with immune checkpoint inhibitors, improves outcomes vs chemotherapy alone for patients (pts) with metastatic (m)TNBC PD-L1+ disease. Most of these pts progress within a year. In a previous study, D (anti-PD-L1) combined with chemotherapy enhanced antitumor immune responses in early TNBC (Loibl. Ann Oncol 2019). In TNBC, activation of the PI3K/AKT/PTEN pathway and high CD73 expression are common. BEGONIA is an ongoing 2-part, multicenter, multi-arm, open-label platform study, evaluating safety and efficacy of D or D+P combined with novel therapies as first-line treatment for mTNBC (NCT03742102). Preliminary results from 2 arms were presented at ASCO 2021 (Abstract #1023). Here, we report results from Arm 1 D+P, Arm 2 D+P+C, and Arm 5 D+P+O. C is an oral, selective, ATP-competitive catalytic inhibitor of all 3 AKT isoforms, and O is a mAb targeting CD73. Methods: Eligible pts had untreated, unresectable, locally advanced or metastatic TNBC. In Arms 1 and 5, pts received D 1500 mg IV Q4W + P 90 mg/m2 IV day (d)1, d8, d15 of every cycle. Pts in Arm 5 also received O 3000 mg IV on d1 and d15 for the first 2 cycles, then Q4W. In Arm 2, pts received D 1500 mg IV Q4W + P 80/90 mg/m2 IV in 4-week cycles (d1, d8, d15, 1 week off) + C 400 mg BID in 4-week cycles (d2-5 × 3 weeks, 1 week off). Primary objectives were safety and tolerability. Secondary endpoints included objective response rate (ORR) and duration of response. Tumors were assessed Q8W per RECIST v1.1. The first 6 pts treated in Arms 2 and 5 were evaluated for dose-limiting toxicities (DLTs), with additional pts enrolled if treatment was tolerated. PD-L1 expression was assessed retrospectively. Previously presented data from Arm 1 D+P, are included for reference (Schmid. ASCO 2021, #1023). Results: In Arm 2 (data cutoff Mar 2021), 30 pts received D+P+C (15 P[80], 15 P[90]; total 13 ongoing); 2 pts (6.7%) discontinued all treatment due to AEs. The rates of dose delays were 13 pts (43%) for D and 15 (50%) for P; dose interruptions were 1 (3%) for D, 12 (40%) for P, 15 (50%) for C; dose reductions were 12 (40%) for P and 14 (47%) for C. Treatment-related (tr)SAEs and G3/4 trAEs were experienced by 7 (23%) and 22 (73%) pts. In Arm 5 (data cutoff Sep 2020), 33 pts received D+P+O (14 ongoing); no pts discontinued due to AEs. The rates of dose delays were 13 pts (39%) for D, 10 (30%) for P, 10 (30%) for O; dose interruptions were 2 (6%) for D, 10 (30%) for P, 3 (9%) for O; and dose reductions were 12 (36%) for P. trSAEs and G3/4 trAEs were experienced by 1 (3%) and 5 (15%) pts. In both arms, there were no DLTs or deaths due to AEs. The Table presents follow-up time and efficacy outcomes for Arms 1, 2, and 5. Responses were observed regardless of PD-L1 expression. The potential value of mutations in the PI3K pathway and CD73 expression as predictive biomarkers will be discussed for Arms 2 and 5, respectively. Updated data for Arm 1 will be presented. Conclusions: The safety profiles of triplet combinations in Arms 2 and 5 were consistent with the individual agents; however, in Arm 2, there was a relatively high rate of G3/4 trAEs but a low discontinuation rate for AEs. Although BEGONIA was not designed to compare activity across arms and numbers were small, the ORR of each triplet therapy was numerically similar to D+P. Biomarker analysis may elucidate pts that benefit from the combination of C or O with D+P. Funding: AstraZeneca Table. Efficacy outcomes in Arms 1, 2, and 5 of BEGONIAArm 1Arm 2Arm 5D+P N=23D+P(80)+C n=15D+P(90)+C n=15All D+P+C N=30D+P+O N=33Duration of follow-up at data cutoff, months, median (range)16.6 (8.5-19.8)6.7 (2-9)16.8 (6-21)8.2 (2-21)8.6 (4.1-14.6)Confirmed ORR, n (%)13 (56.5)8 (53.3)8 (53.3)16 (53.3)15 (45.5)95% CI34.5-76.826.6-78.726.6-78.7NC28.1-63.3CR, n10111PR12871514SD (Unconfirmed PR)7 (3)6 (2)4 (2)10 (4)13 (4)PD31345Percentage with ongoing response at data cutoff53.8%75.0%25.0%50.0%66.7%Arm 1 data cutoff was Sep 2020. C, capivasertib; CI, confidence interval; CR, complete response; D, durvalumab; NC, not calculable; O, oleclumab; ORR, objective response rate; P, paclitaxel; PD, progressive disease; PR, partial response; SD, stable disease. Citation Format: Peter Schmid, Zbigniew Nowecki, Seock-Ah Im, Wei-Pang Chung, Simon Lord, Anne Armstrong, Cynthia X Ma, Robert Huisden, Ross Stewart, Rakesh Kumar, Gaia Schiavon, Hannah Dry, Ana Nunes, Kyung Hae Jung, Yeon Hee Park. BEGONIA: Phase 1b/2 study of durvalumab (D) combinations in locally advanced/metastatic triple-negative breast cancer (TNBC): Results from Arm 1 D + paclitaxel (P), Arm 2 D+P + capivasertib (C), and Arm 5 D+P + oleclumab (O) [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr PD10-03.

437 Background: The prognosis for patients (pts) with advanced UC remains poor, particularly for those unable to tolerate platinum-based chemotherapy. Defects in DNA damage repair (e.g., mutations in homologous recombination repair [HRR] genes) are common in UC and render tumor cells sensitive to poly(ADP-ribose) polymerase (PARP) inhibition. HRR gene mutations (HRRm) and PARP inhibition may enhance the antitumor response of immune checkpoint inhibitors. We conducted a randomized phase II study to evaluate D (anti–PD-L1) in combination with O (a PARP inhibitor) or placebo (P) as a first-line treatment for platinum-ineligible pts with unresectable, stage IV UC (BAYOU; NCT03459846). Methods: Eligible pts were an age of ³18 years with an ECOG performance status (PS) of 0, 1, or 2, histologically or cytologically confirmed transitional cell carcinoma, and who had not received prior systemic therapy for unresectable, stage IV disease. Pts were randomized 1:1 to receive D (1500 mg IV q4w) plus O (orally at 300 mg BID) vs D (1500 mg IV q4w) plus O-matching placebo (P). Pts were stratified according to centrally-determined HRR status (mutant vs wild-type) and Bajorin risk index (a composite of visceral metastases and ECOG PS [0, 1 vs 2]). The primary endpoint was progression-free survival (PFS) by RECIST v1.1 (investigator assessed) in the intention-to-treat (ITT) population. Secondary endpoints included overall survival (OS) in the ITT population and PFS in the subset of pts with HRRm. The data cutoff occurred on October 15, 2020. Results: A total of 154 pts were randomized to receive D+O (n = 78) or D+P (n = 76). Among all randomized pts at baseline, 17%, 42%, and 40% had an ECOG PS of 0, 1, or 2, respectively, and 20% had an HRRm. Median PFS was not significantly different between D+O and D+P in the ITT population (Table). In the subset of pts with HRRm, median PFS was 5.6 months in the D+O group and 1.8 months in the D+P group (Table). In the ITT population, median OS (95% CI) was 10.2 months (7.0–13.9) in the D+O group and 10.7 months (7.2–17.3) in the D+P group (HR 1.07, 95% CI 0.72–1.61). Among all treated pts, grade 3 or 4 treatment-related adverse events occurred in 18% and 9% in the D+O and D+P groups, respectively, with one death due to anemia in the D+P group. Conclusions: The BAYOU study did not meet its primary endpoint. However, the results of pre-planned secondary analyses suggest a potential role for PARP inhibition in UC pts harboring HRRm. No new safety signals were observed. Clinical trial information: NCT03459846. [Table: see text]

1023 Background: Chemotherapy with immune checkpoint inhibitors can improve outcomes vs chemotherapy alone in patients (pts) with metastatic TNBC; however, many still have poor clinical outcomes. BEGONIA is an ongoing 2 part, multicenter, multiarm, open-label platform study evaluating safety and efficacy of D (anti–PD-L1)+P and D±P combined with novel therapies as first-line (1L) treatment for metastatic TNBC (NCT03742102). We report initial results from Part 1 of Arm 1, D+P, and Arm 6, D+T-DXd, an antibody-drug conjugate comprising an anti-HER2 antibody, tetrapeptide-based cleavable linker, and topoisomerase I inhibitor payload. Methods: Eligible pts had untreated unresectable locally advanced or metastatic TNBC. Pts with HER2-low–expressing tumors (IHC 2+/ISH–, IHC 1+/ISH–, or IHC 1+/ISH untested) per local testing were assigned to the D+T-DXd arm. Pts received D (1500 mg IV Q4W)+P (90 mg/m2 IV Day 1, 8, 15 Q4W) in Arm 1 and D (1120 mg IV)+T-DXd (5.4 mg/kg IV) Q3W in Arm 6, until progression or unacceptable toxicity. Primary objectives are safety and tolerability. Secondary endpoints include objective response rate (ORR), duration of response (DoR), and progression-free survival (PFS). Tumors were assessed Q8W (D+P) or Q6W (D+T-DXd). The first 6 pts treated with D+T-DXd were evaluated for dose-limiting toxicities (DLTs), with additional pts enrolled if D+T-DXd was tolerated. Study arms are noncomparable due to differing eligibility criteria, treatments, and data maturity. Results: Arm 1 D+P (data cutoff Sep 2020): 23 pts received D+P (7 ongoing); 2 discontinued D+P due to AEs. Median follow-up time was 16.6 (range 8.5–19.8) mos. Any Grade 3/4 AEs and SAEs were experienced by 10 (44%) and 1 (4%) pts, respectively. D dose was delayed for 7 (30%) pts. Confirmed ORR was 13/23 (57%) with 54% of those remaining in response at 12 mos (median DoR not reached). Median PFS was 7.3 (95% CI 5.4–13.8) mos in the D+P arm. Arm 6 D+T-DXd (data cutoff Nov 2020): 11 pts received D+T-DXd to date (all ongoing). Median follow-up time was 2.3 (0–6) mos. Any Grade 3/4 AEs and SAEs were experienced by 4 (36%) and 1 (9%) pts, respectively. Pts who received D+T-DXd had no DLTs and 1 had a Grade 1 troponin increase. D dose was delayed and T-DXd dose reduced for 2 (18%) pts each. Confirmed ORR was 4/4 (100%; only 4 pts had the opportunity to complete 2 on-treatment disease assessments) with all 4 remaining in response at data cutoff (median DoR not reached). Conclusions: D+P demonstrated a tolerable safety profile and response rate as expected for a 1L TNBC IO/taxane combination. D+T-DXd showed promising early safety and efficacy in 1L HER2-low–expressing TNBC; pt evaluation and enrollment for D+T-DXd are ongoing. D+T-DXd data will be updated and the impact of PD-L1 expression in both arms will be examined. Clinical trial information: NCT03742102 .

TPS1105 Background: Patients (pts) with mTNBC have limited treatment options and poor prognosis. The combination of immune checkpoint inhibitors with chemotherapy shows promise, but only a subset of pts with mTNBC derive benefit, highlighting the need for new combinations. BEGONIA is an ongoing Simon 2-stage, multicenter, multi-arm platform study evaluating the safety and efficacy of D, an anti–PD-L1 monoclonal antibody, with or without P, in combination with novel oncology therapies as first-line treatment for mTNBC (NCT03742102). Dato-DXd is an antibody-drug conjugate (ADC) consisting of a humanized anti-trophoblast cell surface antigen 2 (TROP2) IgG1 monoclonal antibody, a stable tetrapeptide-based cleavable linker, and a topoisomerase I inhibitor payload. Dato-DXd displayed encouraging clinical activity with a manageable safety profile in heavily pretreated pts with metastatic NSCLC in the phase 1 TROPION-PanTumor01 (NCT03401385) study. TROP2 is highly expressed on breast and other epithelial tumors, and a TROP2 ADC showed activity in heavily pretreated pts with mTNBC (Bardia, NEJM 2019). Methods: Eligible female pts are aged ≥18 years with untreated unresectable, locally advanced or mTNBC, ≥12 months since prior taxane therapy, ECOG PS 0/1, adequate organ function, and ≥1 nonirradiated measurable lesion. For Arm 7, pts are excluded if they have clinically significant corneal disease, history of interstitial lung disease/pneumonitis, underlying pulmonary disorder, or prior treatment with an ADC containing a topoisomerase I inhibitor. Arm 7 will evaluate D (1120 mg) + Dato-DXd (6 mg/kg) given intravenously every 3 weeks until disease progression or unacceptable toxicity. Part 1 of each arm includes a total of 30 pts with a safety run-in (n=6) to observe dose-limiting toxicities, identify the recommended phase 2 dose (RP2D), and detect an efficacy signal for part 1 expansion. The primary endpoint of part 1 is safety and tolerability. Secondary endpoints include investigator-assessed objective response rate (ORR), duration of response, progression-free survival (PFS), and overall survival (OS). Once the RP2D has been established for part 1, a futility analysis will be performed with an option to expand the cohort to an additional 27 pts if expansion criteria are met. The primary endpoint for part 1 is ORR. Tumors will be assessed every 6 weeks per RECIST v1.1. Kaplan-Meier analysis will be used for PFS and OS. PD-L1 and TROP2 expression will be assessed by immunohistochemistry. Enrollment is ongoing. Clinical trial information: NCT03742102 .

Abstract Relapsed/refractory DLBCL is an aggressive B-cell malignancy with limited treatment options. BTK inhibitors have demonstrated preclinical and clinical activity in DLBCL of the activated B-cell (ABC) subset, but responses are limited and not durable. Therefore, an acalabrutinib (BTK inhibitor) combination screen was conducted in a panel of 9 DLBCL cell lines to identify synergistic and active combinations. The in vitro combination of acalabrutinib plus capivasertib (AKT inhibitor) demonstrated significant combination benefit in the ABC-DLBCL cell lines TMD8 (Loewe synergy score 9.3) and OCI-LY10 (Loewe synergy score 3.2). Capivasertib and acalabrutinib monotherapy gave 0% and 85% tumor growth inhibition (TGI) in TMD8 and 5% and 79% in OCI-LY10 tumour xenograft models respectively. The combination gave tumour regressions of 99% in TMD8 and 72% in OCI-LY10. To explore a potential mechanism of action, RNAseq analysis was performed on the TMD8 cell line and TMD8 xenograft tumors treated with the monotherapies and combination. 24-hour monotherapy treatment of TMD8 cells with acalabrutinib altered the expression of 7390 genes while capivasertib altered 398 genes (absolute fold change ≥ 1.25 and adjusted p-value < 0.05), with enrichment for genes regulated by NFkB signalling detected. Pathway analysis following combination treatment revealed significant decrease in expression of the G2M checkpoint pathway genes compared to acalabrutinib alone (Adjusted p-value = 0.007) as well as decreased expression of CDK1, AURKA and MYC, and significant shifts in the TNFa signalling via NFkB pathway (Adjusted p-value = 0.02). The NFkB signalling node was examined in more detail in TMD8 tumor samples treated with the combination. Lower expression of NFKBIA, NFKBID, EGR2 and BCL2A1 was evident in the combination group, compared to control tumors (p<0.01 for all). Interestingly, the combination strongly increased the expression of MS4A2 (CD20) compared to control (Adjusted p-value = 0.002), capivasertib monotherapy (Adjusted p-value = 0.004) and acalabrutinib monotherapy (Adjusted p-value = 0.02). Therefore, we tested the addition of Rituxan to acalabrutinib + capivasertib combination in the TMD8 xenograft model. The triple combination produced durable complete regressions in 5/5 mice after cessation of treatment whereas tumors regrew after cessation of treatment of the acalabrutinib + capivasertib doublet. These data suggest that the combination of BTK and AKT inhibition may enhance anti-tumor activity in ABC DLBCL, with the addition of anti-CD20 giving more durable tumour control. Citation Format: Kathleen Burke, Justine Roderick-Richardson, Natasha Narang, Brandon Willis, Hannah Dry, Lillian Castriotta, Alan Rosen, Jay Mettetal, Simon Barry, Andrew Bloecher. Combination activity of acalabrutinib and capivasertib in diffuse large B-cell lymphoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1024.

Diffuse large B-cell lymphoma (DLBCL) is the most common B-cell malignancy among adults and despite approximately 65% of patients with DLBCL being cured with RCHOP therapy, nonresponsive and relapsed patients have inadequate treatment options, highlighting the importance for innovative treatment regimens. Blockade of B-cell receptor (BCR) downstream signaling components with various targeted agents is emerging as a clinically tractable treatment strategy across multiple B-cell malignancies. Protein Kinase B (AKT) signaling downstream of the BCR complex has been shown to be a central node in germinal center B-cell (GCB) DLBCL and the potent, selective inhibitor of AKT1, AKT2, AKT3, capivasertib, currently being evaluated in multiple clinical trials by targeting AKT-driven solid cancers, has been shown to induce apoptosis in a subset of GCB-DLBCL cell lines and cause tumor stasis in xenograft mouse models (Erdman et al., 2017). Since the monotherapy capivasertib responses in GCB DLBCL models are partial and lack durability, we hypothesized a combination approach could deliver even greater therapeutic benefit. To identify optimal partners, we conducted a capivasertib centric in vitro combination screen with specific with BH3 family members across a panel of 15 DLBCL cell lines, which revealed a synergistically active combination with the BCL2 inhibitor, venetoclax which is currently being evaluated in DLBCL. The activity was specifically enhanced in cell lines of the GCB subtype, with 4 PTEN del and 2 PTEN wt cell line models showing combination benefit. To determine the ability of this combination to drive stronger and durable responses, we assessed capivasertib and ventoclax activity in xenograft mouse models using two GCB-DLBCL cell line lines, SUDHL4 (PTEN wt) and WSU-DLCL2 (PTEN del). Oral administration of either monotherapy capivasertib (130 mg/kg BID, 4-day on/3-day off) or venetoclax (100 mg/kg QD) provided partial tumor growth inhibition (capivasertib TGI = 74% in SUDHL4 and 29% in WSU-DLCL2, and venetoclax TGI = 46% in SUDHL4 and 0% in WSU-DLCL2), whereas the combination of capivasertib and venetoclax both on a 4-day on/3-day off schedule produced complete tumor regression (100% regression) in both xenograft GCB cell line models during the dosing period. Notably, in both xenograft models all mice (5/5 per model) remained tumor free for at least 30 days following dosing cessation demonstrating high durability of response for the combination. Additionally, this combination is currently being evaluated in clinically relevant GCB and non-GCB PDX mouse models. Taken together, our results provide preclinical evidence for the rational combination of AKT and BCL-2 blockade with capivasertib and venetoclax respectively in patients with relapsed/refractory GCB-DLBCL.

Spleen Tyrosine Kinase (SYK) is a well-studied enzyme with therapeutic applications in oncology and autoimmune diseases. We identified an azabenzimidazole (ABI) series of SYK inhibitors by mining activity data of 86,000 compounds from legacy biochemical assays with SYK and other homologous kinases as target enzymes. A structure-based design and hybridization approach was then used to improve the potency and kinase selectivity of the hits. Lead compound 23 from this novel ABI series has a SYK IC50 = 0.21 nM in a biochemical assay and inhibits growth of SUDHL-4 cells at a GI(50) = 210 nM.

Spleen tyrosine kinase (SYK) is a non-receptor cytosolic kinase. Due to its pivotal role in B cell receptor and Fc-receptor signaling, inhibition of SYK has been targeted in a variety of disease areas. Herein, we report the optimization of a series of potent and selective SYK inhibitors, focusing on improving metabolic stability, pharmacokinetics and hERG inhibition. As a result, we identified 30, which exhibited no hERG activity but unfortunately was poorly absorbed in rats and mice. We also identified a SYK chemical probe, 17, which exhibits excellent potency at SYK, and an adequate rodent PK profile to support in vivo efficacy/PD studies.

Hybridisation of amino-pyrimidine based SYK inhibitors (e.g. 1a) with previously reported diamine-based SYK inhibitors (e.g. TAK-659) led to the identification and optimisation of a novel pyrimidine-based series of potent and selective SYK inhibitors, where the original aminomethylene group was replaced by a 3,4-diaminotetrahydropyran group. The initial compound 5 achieved excellent SYK potency. However, it suffered from poor permeability and modest kinase selectivity. Further modifications of the 3,4-diaminotetrahydropyran group were identified and the interactions of those groups with Asp512 were characterised by protein X-ray crystallography. Further optimisation of this series saw mixed results where permeability and kinase selectivity were increased and oral bioavailability was achieved in the series, but at the expense of potent hERG inhibition.

Introduction The activated B cell like (ABC) subtype of DLBCL has a 40% cure rate with currently available therapies [1] - worse than the rate for germinal center B-cell like (GCB) DLBCL, which highlights the need for ABC subtype-specific treatment strategies. Bruton's tyrosine kinase (BTK) links the activity of the B cell receptor (BCR) to NF-κB and is essential for the survival of ABC cell lines with chronic active BCR signaling. BTK selective covalent inhibitors such as ibrutinib and acalabrutinib are effective in blocking BTK activation and reducing downstream NF-κB pathway activity. However, in ABC DLBCL patients, the observed response rate to ibrutinib is 37% (14/38) and the median PFS is only about 2 months [1]. Many patients show primary resistance to the drug or develop secondary resistance. To improve patient outcomes, a number of combination treatments along with BTK inhibition may be considered. The goal of this work is to integrate data on ABC DLBCL signaling and tumor effect, as well as its pharmacological modulation into one common quantitative systems pharmacology (QSP) modeling framework, to better understand potential efficacy benefits when adding combination partners to a BTK inhibitor. Methods A fit-for-purpose mechanistic model of ABC DLBCL signaling linked to cell cycle and cell death was developed, based on literature curation and in vitro and in vivo data in TMD8 cell lines. TMD8 cells carry activating mutations in the BCR adaptor protein CD79B and in the TLR adaptor protein MYD88. Chronic BCR signaling in ABC DLBCL activates downstream NF-κB through signaling of the BTK as well as the PI3K/AKT/mTOR pathways (Fig. 1). The L265P mutated isoform of MYD88 spontaneously activates NF-κB in a BCR-independent manner. In the cell cycle / cell death part of the model, transition rates were regulated by relevant model variables of signaling pathways (NF-κB, AKT, mTOR activation). Efficacy (tumor size modulation) was implemented through quantitative PK/PD data obtained from TMD8 xenograft studies in CB.17 SCID mice treated with acalabrutinib, as well as mTOR and AKT inhibitors. Results Individual animal tumor size dynamics were studied in control and treatment groups: BTKi (acalabrutinib), AKTi (AZD5363), mTORi (everolimus and AZD2014), as monotherapies and in combinations with acalabrutinib. Interestingly, there was no statistically significant difference in tumor size dynamics, between the control arm and the AKTi monotherapy group. Acalabrutinib monotherapy showed only a moderate decrease in tumor size, with no observation of full tumor rejection. However, acalabrutinib combined with mTORi or AKTi achieved 100% tumor rejection. The model adequately described tumor size dynamics with acalabrutinib and mTORi/AKTi combinations. In order to improve model fitting, we are now taking enhanced activation of the PI3K/AKT/mTOR pathway into consideration, to further evaluate the underlying mechanism for synergy between acalabrutinib and AKTi. Discussion Enhanced AKT activation induction has been observed in BTKi treatment refractory cell lines [2] and may explain primary resistance to, or limited efficacy of BTK inhibitors in some ABC DLBCL patients (while other mechanisms of primary resistance are known). This mechanism may help lymphoma cells to strive, chronically, under BTK inhibitor treatment, while at the same time increase the probability of gaining mutations such as BTK C481S [3], which may further lead to secondary resistance. Combination of an AKT inhibitor with acalabrutinib may help circumvent both primary and secondary (acquired) resistance in ABC-DLBCL. References 1. Wilson W.H., et al. (2017) Targeting B cell receptor signaling with ibrutinib in diffuse large B cell lymphoma. Nature Med 21, 922-27. 2. Kim J.H., et al. (2015) CD79B limits response of diffuse large B cell lymphoma to ibrutinib. Leukemia & Lymphoma http://dx.doi.org/10.3109/10428194.2015.1113276. 3. BTK C481S resistance mechanism Chen J.G., et al. (2018) BTKcys481Ser drives ibrutinib resistance via ERK1/2 and protects BTK wild type MYD88 mutated cells by a paracrine mechanism. Blood 131(18):2047-2059. Figure 1 Disclosures Yuri: AstraZeneca: Consultancy. Chu:AstraZeneca: Employment. Shah:AstraZeneca: Employment. Vishwanathan:AstraZeneca: Employment. Larsson:AstraZeneca: Employment. Bloecher:Astrazeneca: Employment. Willis:AstraZeneca: Employment. Dry:Astrazeneca: Employment. Peskov:AstraZeneca: Consultancy. Ware:Acerta Pharma: Employment; Astrazeneca: Employment, Equity Ownership. Mortlock:AstraZeneca: Employment, Other: stock holder; Gotham Therapeutics Corp: Consultancy, Other: stock holder. Helmlinger:AstraZeneca: Employment.