Measurement of the Absolute Branching Fraction and Decay Asymmetry of Λ→nγ

The radiative hyperon decay Λ→nγ is studied using (10087±44)×10^{6}  J/ψ events collected with the BESIII detector operating at BEPCII. The absolute branching fraction of the decay Λ→nγ is determined to be (0.832±0.038_{stat}±0.054_{syst})×10^{-3}, which is a factor of 2.1 lower and 5.6 standard deviations different than the previous measurement. By analyzing the joint angular distribution of the decay products, the first determination of the decay asymmetry α_{γ} is reported with a value of -0.16±0.10_{stat}±0.05_{syst}.

Observation of an Isoscalar Resonance with Exotic J^{PC}=1^{-+} Quantum Numbers in J/ψ→γηη^{'}

Using a sample of (10.09±0.04)×10^{9}  J/ψ events collected with the BESIII detector operating at the BEPCII storage ring, a partial wave analysis of the decay J/ψ→γηη^{'} is performed. The first observation of an isoscalar state with exotic quantum numbers J^{PC}=1^{-+}, denoted as η_{1}(1855), is reported in the process J/ψ→γη_{1}(1855) with η_{1}(1855)→ηη^{'}. Its mass and width are measured to be (1855±9_{-1}^{+6})  MeV/c^{2} and (188±18_{-8}^{+3})  MeV, respectively, where the first uncertainties are statistical and the second are systematic, and its statistical significance is estimated to be larger than 19σ.

Observation of an a_{0}-like State with Mass of 1.817 GeV in the Study of D_{s}^{+}→K_{S}^{0}K^{+}π^{0} Decays

Using e^{+}e^{-} annihilation data corresponding to an integrated luminosity of 6.32  fb^{-1} collected at center-of-mass energies between 4.178 and 4.226 GeV with the BESIII detector, we perform the first amplitude analysis of the decay D_{s}^{+}→K_{S}^{0}K^{+}π^{0} and determine the relative branching fractions and phases for intermediate processes. We observe an a_{0}-like state with mass of 1.817 GeV in its decay to K_{S}^{0}K^{+} for the first time. In addition, we measure the ratio {B[D_{s}^{+}→K[over ¯]^{*}(892)^{0}K^{+}]/B[D_{s}^{+}→K[over ¯]^{0}K^{*}(892)^{+}]} to be 2.35_{-0.23stat}^{+0.42}±0.10_{syst}. Finally, we provide a precision measurement of the absolute branching fraction B(D_{s}^{+}→K_{S}^{0}K^{+}π^{0})=(1.46±0.06_{stat}±0.05_{syst})%.

Precise Measurements of Decay Parameters and CP Asymmetry with Entangled Λ-Λ[over ¯] Pairs

Based on 10 billion J/ψ events collected at the BESIII experiment, a search for CP violation in Λ decay is performed in the difference between CP-odd decay parameters α_{-} for Λ→pπ^{-} and α_{+} for Λ[over ¯]→p[over ¯]π^{+} by using the process e^{+}e^{-}→J/ψ→ΛΛ[over ¯]. With a five-dimensional fit to the full angular distributions of the daughter baryon, the most precise values for the decay parameters are determined to be α_{-}=0.7519±0.0036±0.0024 and α_{+}=-0.7559±0.0036±0.0030, respectively. The Λ and Λ[over ¯] averaged value of the decay parameter is extracted to be α_{avg}=0.7542±0.0010±0.0024 with unprecedented accuracy. The CP asymmetry A_{CP}=(α_{-}+α_{+})/(α_{-}-α_{+}) is determined to be -0.0025±0.0046±0.0012, which is one of the most precise measurements in the baryon sector. The reported results for the decay parameter will play an important role in the studies of the polarizations and CP violations for the strange, charmed and beauty baryons.

First Observation of the Direct Production of the χ_{c1} in e^{+}e^{-} Annihilation

We study the direct production of the J^{PC}=1^{++} charmonium state χ_{c1}(1P) in electron-positron annihilation by carrying out an energy scan around the mass of the χ_{c1}(1P). The data were collected with the BESIII detector at the BEPCII collider. An interference pattern between the signal process e^{+}e^{-}→χ_{c1}(1P)→γJ/ψ→γμ^{+}μ^{-} and the background processes e^{+}e^{-}→γ_{ISR}J/ψ→γ_{ISR}μ^{+}μ^{-} and e^{+}e^{-}→γ_{ISR}μ^{+}μ^{-} is observed by combining all the data samples. The χ_{c1}(1P) signal is observed with a significance of 5.1σ. This is the first observation of a C-even state directly produced in e^{+}e^{-} annihilation. The electronic width of the χ_{c1}(1P) resonance is determined to be Γ_{ee}=(0.12_{-0.08}^{+0.13})  eV, which is of the same order of magnitude as theoretical calculations.

Evidence for a Neutral Near-Threshold Structure in the K_{S}^{0} Recoil-Mass Spectra in e^{+}e^{-}→K_{S}^{0}D_{s}^{+}D^{*-} and e^{+}e^{-}→K_{S}^{0}D_{s}^{*+}D^{-}

We study the processes e^{+}e^{-}→K_{S}^{0}D_{s}^{+}D^{*-} and e^{+}e^{-}→K_{S}^{0}D_{s}^{*+}D^{-}, as well as their charge conjugated processes, at five center-of-mass energies between 4.628 and 4.699 GeV, using data samples corresponding to an integrated luminosity of 3.8  fb^{-1} collected by the BESIII detector at the BEPCII storage ring. Based on a partial reconstruction technique, we find evidence of a structure near the thresholds for D_{s}^{+}D^{*-} and D_{s}^{*+}D^{-} production in the K_{S}^{0} recoil-mass spectrum, which we refer to as the Z_{cs}(3985)^{0}. Fitting with a Breit-Wigner line shape, we find the mass of the structure to be (3992.2±1.7±1.6)  MeV/c^{2} and the width to be (7.7_{-3.8}^{+4.1}±4.3)  MeV, where the first uncertainties are statistical and the second are systematic. The significance of the Z_{cs}(3985)^{0} signal is found to be 4.6σ including both the statistical and systematic uncertainty. We report the Born cross section multiplied by the branching fraction at different energy points. The mass of the Z_{cs}(3985)^{0} is close to that of the Z_{cs}(3985)^{+}. Assuming SU(3) symmetry, the cross section of the neutral channel is consistent with that of the charged one. Hence, we conclude that the Z_{cs}(3985)^{0} is the isospin partner of the Z_{cs}(3985)^{+}.

Observation of Resonance Structures in e^{+}e^{-}→π^{+}π^{-}ψ_{2}(3823) and Mass Measurement of ψ_{2}(3823)

Using a data sample corresponding to an integrated luminosity of 11.3  fb^{-1} collected at center-of-mass energies from 4.23 to 4.70 GeV with the BESIII detector, we measure the product of the e^{+}e^{-}→π^{+}π^{-}ψ_{2}(3823) cross section and the branching fraction B[ψ_{2}(3823)→γχ_{c1}]. For the first time, resonance structure is observed in the cross section line shape of e^{+}e^{-}→π^{+}π^{-}ψ_{2}(3823) with significances exceeding 5σ. A fit to data with two coherent Breit-Wigner resonances modeling the sqrt[s]-dependent cross section yields M(R_{1})=4406.9±17.2±4.5  MeV/c^{2}, Γ(R_{1})=128.1±37.2±2.3  MeV, and M(R_{2})=4647.9±8.6±0.8  MeV/c^{2}, Γ(R_{2})=33.1±18.6±4.1  MeV. Though weakly disfavored by the data, a single resonance with M(R)=4417.5±26.2±3.5  MeV/c^{2}, Γ(R)=245±48±13  MeV is also possible to interpret data. This observation deepens our understanding of the nature of the vector charmoniumlike states. The mass of the ψ_{2}(3823) state is measured as (3823.12±0.43±0.13)  MeV/c^{2}, which is the most precise measurement to date.

Observation of a State X(2600) in the π^{+}π^{-}η' System in the Process J/ψ→γπ^{+}π^{-}η'

Based on (10087±44)×10^{6}  J/ψ events collected with the BESIII detector, the process J/ψ→γπ^{+}π^{-}η^{'} is studied using two largest decay channels of the η^{'} meson, η^{'}→γπ^{+}π^{-} and η^{'}→ηπ^{+}π^{-}, η→γγ. A new resonance, which we denote as the X(2600), is observed with a statistical significance larger than 20σ in the π^{+}π^{-}η^{'} invariant mass spectrum, and it has a connection to a structure around 1.5  GeV/c^{2} in the π^{+}π^{-} invariant mass spectrum. A simultaneous fit on the π^{+}π^{-}η^{'} and π^{+}π^{-} invariant mass spectra with the two η^{'} decay modes indicates that the mass and width of the X(2600) state are 2618.3±2.0_{-1.4}^{+16.3}  MeV/c^{2} and 195±5_{-17}^{+26}  MeV, where the first uncertainties are statistical, and the second systematic.

[Veracity of using a visual chart with a testing distance of 2.5 meters for measurement of distance visual acuity in teenagers]

Objective: To compare the results of visual acuity testing for teenagers with visual acuity charts designed at 2.5-meter and 5-meter distances, and to investigate the accuracy of the 2.5-meter visual acuity chart. Methods: It was a self-control study. A total of 227 teenagers (454 eyes) with ametropia who came to the ophthalmic clinic of Peking Union Medical College Hospital from March 2019 to September 2019 were included. There were 123 males and 104 females aged (11.74±3.26) years. The vision examiners were trained in the same testing environment and passed the consistency test. Distance visual acuity of all participants was tested with charts designed at 2.5 meters and 5 meters in a 10-minute interval. According to the age (7-9, 10-12, 13-15 and 16-18 years old) and visual acuity (1.00-0.52, 0.40-0.30 and 0.22-0.10), the results of two kinds of visual acuity charts were compared. The testing order of the two visual charts was randomly determined. The visual acuity results were converted into logMAR values and compared. Paried t-student test was used to compare the difference between two charts, and Pearson correlation test was used to explore the correlation between the results of two charts. Results: The visual acuity of the right eye was 0.37±0.24 (logMAR) at 2.5 meters and 0.50±0.26 (logMAR) at 5 meters. The distance visual acuity measured with the 2.5-meter visual acuity chart was better (t=16.19, P<0.01). The visual acuity of the left eye was 0.36±0.23 (logMAR) at 2.5 meters and 0.45±0.23 (logMAR) at 5 meters (t=11.71, P<0.01). The differences between two charts were larger among teenagers with lower visual acuity (r=0.387,P<0.01). Conclusion: Under the same test conditions, the distance visual acuity measured with a 2.5-meter chart was significantly better than a 5-meter chart. The visual acuity chart designed at 2.5 meters was not an appropriate tool to measure distance vision in adolescents. (Chin J Ophthalmol, 2021, 57: 122-125).

[Long-term effect of anal fistula plug treatment on postoperative anal function in patients with trans-sphincteric perianal fistula and risk factors associated with anal function]

Objective: To evaluate the long-term effects of anal fistula plug treatment on postoperative anal function in patients with trans-sphincteric perianal fistula, and identify risk factors associated with anal function. Methods: A case-control study was conducted. Clinical and follow-up data of 123 patients with trans-sphincteric perianal fistula receiving anal fistula plug treatment in Beijing Chaoyang Hospital from August 2008 to September 2012 were retrospectively analyzed. The follow-up deadline was April 30, 2020. The Wexner score for incontinence was used to evaluate pre-and postoperative anal function (range from 0 to 20, with higher score representing worse function). The potential risk factors affecting postoperative anal function, including gender, age, fasting blood glucose, diabetes, smoking, alcoholism, location of external opening of anal fistula, surgeon expertise and operation time, were statistically analyzed. Results: Among the 123 patients, 114 were male and 9 were female, the median age was 39 (15-69) years, body mass index (BMI) was (26.2±3.9) kg/m(2), and the median distance between the external opening of anal fistula and the anal verge was 2.6 (1.0-5.0) cm. The median operation time was 30.4 (15.0-60.0) minutes. The median follow-up time was 120 (93-141) months. Sixty-nine patients (56.5%) were healed. The assessment of anal function by Wexner incontinence score showed that 33 (26.8%) patients had anal functional decline after surgery, and the postoperative median Wexner score was 1.34 (0-8), which was significantly higher than preoperative score of 0.17 (0-4) (Z=-5.057, P<0.001). Compared with preoperative levers, postoperative subscores of flatus incontinence, liquid incontinence, solid incontinence and alteration in lifestyle were increased significantly (all P<0.05). Subgroup analysis showed that both in the healed and unhealed groups, the postoperative Wexner scores were higher than those before surgery [healed group: 1.22 (0-8) vs. 0.17 (0-1), Z=-3.796, P<0.001; unhealed group: 1.5 (0-8) vs.0.17 (0-3), Z=-3.422, P=0.001]. Univariate analysis revealed that 33 patients with postoperative anal functional decline had higher BMI, higher fasting blood glucose, higher proportion of alcoholism, longer distance between external opening of anal fistula and the anal verge, and longer operation time (all P<0.05). Multivariate logistic regression analysis testified that higher BMI (OR=1.485, 95% CI: 1.220-1.807, P<0.001) and longer distance between external opening and anal verge (OR=2.207, 95% CI: 1.276-3.220, P=0.003) were independent risk factors for postoperative anal functional decline. Conclusions: The treatment for trans-sphincteric anal fistula with anal fistula plug leads to long-term postoperative anal function decline. For patients with obesity and longer distance between external opening of anal fistula and the anal verge, this procedure should be performed with particular caution, and the anal sphincter should be preserved as much as possible during the operation.

Abstract 1958: Repotrectinib increases effectiveness of KRAS-G12C inhibitors in KRAS-G12C mutant cancer models via simultaneous SRC/FAK/JAK2 inhibition

KRAS is frequently mutated in multiple cancer types. Therapeutic targeting of KRAS has proven challenging until recent success of KRAS-G12C inhibitor AMG510 that demonstrated tumor regression in lung and colon cancer patients with a KRAS-G12C mutation. However, resistance via feedback reactivation or development of a bypass are expected to limit anti-tumor efficacy of KRAS-G12C inhibitors, favoring a combination approach. Adaptive upregulation of the PI3K/AKT signaling pathway has been recognized as a common resistance mechanism that promotes cancer cell survival and may temper efficacy of KRAS-G12C inhibitors. SRC/FAK signaling promotes tumor cell survival by activation of the PI3K/AKT survival pathway supporting concomitantly targeting SRC/FAK as a promising strategy to potentiate KRAS G12C inhibitors. In addition, oncogenic KRAS induces secretion of various cytokines and growth factors leading to modulation of the tumor microenvironment to promote tumor growth. Targeting the cytokine secretion pathway via JAK2/STAT3 modulation may be important to overcome the resistance to direct KRAS inhibition. Therefore, combinations of KRAS inhibitors with agents that target apoptotic processes and feedback reactivation may represent a promising therapeutic approach. Repotrectinib, a next generation ROS1/TRK/ALK inhibitor, also inhibits SRC/FAK/JAK2 at therapeutically relevant concentrations. Here, we present synergistic effects of repotrectinib in combination with a KRAS-G12C inhibitor in KRAS-G12C mutant cancer models via simultaneous inhibition of SRC/FAK/JAK2. Adding repotrectinib to AMG510 improves AMG510 effectiveness on KRAS-G12C mutant cancer cells with notably increased apoptosis. For example, repotrectinib (1 μM) shifted the antiproliferation IC50 of AMG510 from 213 nM to 3 nM in KRAS-G12C mutant H358 cells. Treatment of H358 cells with AMG510 alone (100 nM) or repotrectinib alone (1 µM) resulted in slight increases in cleaved PARP and caspase-3 proteins, whereas larger increases were observed with the combination. Although high levels of phosphorylated ERK, AKT, STAT3 and FAK were detected in H358 cells, AMG510 (100 nM) was only able to partially modulate phospho-ERK (pERK) with no modulation on pAKT, pSTAT3 and pFAK and repotrectinib (1 μM) suppressed pSTAT3 and pFAK with minimum modulation on pERK and pAKT. The combination in H358 cells results in stronger suppression of pERK and pAKT than either single agent alone, which is consistent with the observed increase in activation of apoptosis. Additional combination data in KRAS-G12C mutant cancer models will be presented. Overall, these studies warrant further clinical investigation on the combination of KRAS-G12C inhibitors with repotrectinib in patients with KRAS-G12C mutation for potential response and duration improvement of current investigational KRAS-G12C inhibitors.

Citation Format: J. Jean Cui, Dayong Zhai, Wei Deng, Laura Rodon, Nathan Lee, Brion Murray. Repotrectinib increases effectiveness of KRAS-G12C inhibitors in KRAS-G12C mutant cancer models via simultaneous SRC/FAK/JAK2 inhibition [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1958.

Repotrectinib Exhibits Potent Antitumor Activity in Treatment-Naïve and Solvent-Front-Mutant ROS1-Rearranged Non-Small Cell Lung Cancer

PURPOSE

Although first-line crizotinib treatment leads to clinical benefit in ROS1⁺ lung cancer, high prevalence of crizotinib-resistant ROS1-G2032R (ROS1^G2032R) mutation and progression in the central nervous system (CNS) represents a therapeutic challenge. Here, we investigated the antitumor activity of repotrectinib, a novel next-generation ROS1/TRK/ALK-tyrosine kinase inhibitor (TKI) in ROS1⁺ patient-derived preclinical models.

EXPERIMENTAL DESIGN

Antitumor activity of repotrectinib was evaluated in ROS1⁺ patient-derived preclinical models including treatment-naïve and ROS1^G2032R models and was further demonstrated in patients enrolled in an on-going phase I/II clinical trial (NCT03093116). Intracranial antitumor activity of repotrectinib was evaluated in a brain-metastasis mouse model.

RESULTS

Repotrectinib potently inhibited in vitro and in vivo tumor growth and ROS1 downstream signal in treatment-naïve YU1078 compared with clinically available crizotinib, ceritinib, and entrectinib. Despite comparable tumor regression between repotrectinib and lorlatinib in YU1078-derived xenograft model, repotrectinib markedly delayed the onset of tumor recurrence following drug withdrawal. Moreover, repotrectinib induced profound antitumor activity in the CNS with efficient blood-brain barrier penetrating properties. Notably, repotrectinib showed selective and potent in vitro and in vivo activity against ROS1^G2032R. These findings were supported by systemic and intracranial activity of repotrectinib observed in patients enrolled in the on-going clinical trial.

CONCLUSIONS

Repotrectinib is a novel next-generation ROS1-TKI with improved potency and selectivity against treatment-naïve and ROS1^G2032R with efficient CNS penetration. Our findings suggest that repotrectinib can be effective both as first-line and after progression to prior ROS1-TKI.

[Long-term efficacy of bioprosthetic anal fistula plug in the treatment of transsphincteric anal fistula]

Objective: To evaluate the long-term healing rate of transsphincteric anal fistula treated with anal fistula plug procedure and the risk factors affecting the healing of anal fistula. Methods: A retrospective case-control study was conducted to analyze the clinical data of 207 patients with transsphincteric anal fistulas who received anal fistula plug procedure at the Department of General Surgery, Beijing Chaoyang Hospital of Capital Medical University from August 2008 to September 2012. Inclusion criteria: (1) consistent with the diagnosis of transsphincteric anal fistula: the anal fistula passed through the internal and external sphincter; (2) complete data; (3) initial treatment with anal fistula plug procedure. Exclusion criteria: (1) acute rectal or perianal infection or poorly controlled focal infection; (2) recent incision and drainage of perianal abscess or spontaneous rupture of abscess; (3) patients with malignant tumor; (4) patients with Crohn's disease or ulcerative colitis; (5) patients with heart, liver, brain, lung or renal insufficiency; (6) cachexia due to various chronic wasting diseases; (7) patients could not tolerate surgery. Patients were followed up for anal fistula healing. The cumulative healing rate of patients with transsphincteric anal fistula was plotted using the Kaplan-Meier method, and the factors affecting anal fistula healing were explored by univariate and multivariate logistic regression analysis. Results: There were 186 males and 21 females with age of 15 to 69 (mean 38) years. The duration of anal fistula was 3-60 (mean 15) months. Three patients had a history of previous episodes of perianal abscess and underwent incision and drainage of perianal abscess (all more than 3 months). During follow-up ending on October 31, 2018, 72 patients (34.8%) were lost to follow-up. Among 135 patients who were successfully followed up, the average follow-up period was 96 (75-124) months. Seventy-five patients had anal fistula healing, with healing rate of 55.6%. Kaplan-Meier survival curve showed that the healing time of anal fistula was prolonged and finally stabilized at 55.6%. In the patients who failed initial treatment with anal fistula plug packing, there were 6 cases whose anal fistula healed spontaneously without other treatment. Among them, 3 cases healed spontaneously 2 years and 3 cases 3 years after operation without recurrence. From 2008 to 2012, the annual healing rates of anal fistula plug treatment were 3/6, 61.5% (24/39), 42.1% (24/57), 12/15 and 12/18, respectively. Multivariate logistic regression analysis showed that the duration of anal fistula≥6 months (OR=3.187, 95% CI: 1.361-7.466, P=0.008) was an independent risk factor for anal fistula healing after treatment with anal fistula plug. Conclusion: The long-term efficacy of anal fistula plug procedure in the treatment of transsphincteric anal fistula is positive, and this procedure should be implemented as soon as possible.

Abstract 1325: TPX-0022, a polypharmacology inhibitor of MET/CSF1R/SRC inhibits tumor growth by promoting anti-tumor immune responses

In the tumor microenvironment, tumor associated macrophages (TAMs) support tumor growth by suppressing antitumor immune responses and promoting angiogenesis, which is associated with disease progression and poor clinical outcomes. In contrast to the classic phagocytic and cytotoxic pro-inflammatory M1 phenotype of macrophages engulfing and digesting pathogens, TAMs often adopt the anti-inflammatory and immune regulatory M2 phenotype in response to colony stimulating factor 1 (CSF1), which is produced by either tumor cells or stroma cells. Signaling through colony stimulating factor 1 receptor (CSF1R), a receptor tyrosine kinase expressed on the surface of mononuclear phagocytes, is involved in the recruitment of TAMs and has been associated with tumor progression and suppression of the immune response. Thus, CSF1R represents a key therapeutic target. TPX-0022, a type I kinase inhibitor with a novel macrocyclic structure, has been designed and optimized to inhibit MET/CSF1R/SRC with enzymatic kinase inhibition IC50s of 0.14, 0.76 and 0.12 nM, respectively. In a Ba/F3 ETV6-CSF1R cell model, TPX-0022 inhibited both autophosphorylation of CSF1R with an IC50 &lt;3 nM and cell growth with an IC50 of 14 nM. In addition, TPX-0022 effectively inhibited the growth of Ba/F3 ETV6-CSF1R xenograft tumors in vivo. In the CSF1/CSF1R signaling-dependent M-NFS-60 model, TPX-0022 not only exhibited potency with an IC50 of 0.3 nM under baseline condition, but also potently inhibited the growth of M-NFS-60 cells with an IC50 of 11.6 nM in the presence of exogenous CSF1 at 1 ng/mL concentration, a condition mimicking typical in vivo conditions in the presence of advanced tumors. In contrast, in our study, the potency of the type II CSF1R inhibitor PLX-3397 demonstrated a strong dependency on the concentration of mouse CSF1, as the anti-proliferation IC50 shifted from &lt;0.1 nM to 146.4 nM when CSF1 concentration changed from baseline to 1 ng/mL. Finally, in the MC38 syngeneic mouse model, TPX-0022 effectively reduced TAMs, altered the polarity of TAMs toward a more M1 phenotype, increased cytotoxic T cells and inhibited the growth of MC38 tumors. These preclinical results demonstrated a potent CSF1R inhibitory activity of TPX-0022 and the ability of TPX-0022 to inhibit tumor growth and promote a pro-inflammatory anti-tumor microenvironment.

Citation Format: Wei Deng, Dayong Zhai, Evan Rogers, Xin Zhang, Dong Lee, Jane Ung, Han Zhang, Jing Liu, Yuelie Lu, John Huang, Armin Graber, Zach Zimmerman, John Lim, Jeffrey Whitten, J. Jean Cui. TPX-0022, a polypharmacology inhibitor of MET/CSF1R/SRC inhibits tumor growth by promoting anti-tumor immune responses [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1325.

Abstract 442: Repotrectinib, a next generation TRK inhibitor, overcomes TRK resistance mutations including solvent front, gatekeeper and compound mutations

Oncogenic TRKA/B/C fusions are identified in multiple cancer types in adults and children. TRK inhibitors (TRKis) have demonstrated marked efficacy in patients with these cancers, however, acquired on-target resistance mediated by kinase domain mutations can occur. Next-generation TRKis targeting both wildtype and mutant TRK fusions can address this unmet need. Repotrectinib was designed to potently inhibit wildtype (WT) TRKs and overcome resistance mutations. The anti-proliferative activity of 1st generation (larotrectinib/entrectinib) and next-generation (repotrectinib/LOXO-195) TRKis were compared using engineered Ba/F3 cells expressing WT or mutated TRKs (Table). Repotrectinib was over 10-fold more potent than LOXO-195 against WT TRK fusions and solvent front mutations (SFMs), and more than 100-fold more potent against the gatekeeper mutations TRKA F589L and TRKC F617I. Furthermore, repotrectinib was the only TRKi active against the compound mutation TRKA G595R/F589L in cis in preclinical Ba/F3 cells. In xenograft tumor models, repotrectinib led to significant tumor regression in tumors carrying WT or mutated TRK fusions. In the ongoing TRIDENT-1 phase 1 clinical trial of repotrectinib (NCT03093116), the SFMs TRKA G595R, TRKC G623R and TRKC G623E and the gatekeeper mutation TRKA F589L were detected in plasma cfDNA samples at baseline from three TRKi-resistant patients. Repotrectinib was active against ETV6-TRKC G623E in an entrectinib-resistant patient with a salivary gland tumor (-82%, confirmed partial response, RECIST v1.1). Tumor regression (-33%) was achieved in a larotrectinib-resistant cholangiocarcinoma patient with LMNA-TRKA G595R and F589L mutations in trans. TRIDENT-1 is currently enrolling NTRK fusion-positive patients with advanced solid tumors.

Ba/F3 Cell Proliferation Assay IC50 (nM)LMNA-TRKAETV6-TRKBETV6-TRKCTRK InhibitorWTG595RG667CF589LG595R/F589LWTG639RWTG623RG623EF617IRepotrectinib&lt;0.10.19.2&lt;0.117.4&lt;0.13.2&lt;0.10.40.9&lt;0.2LOXO-1958.613.194.931.6531.11.028.41.724.649.153Larotrectinib15.918981863625.31000013.1300023.2699921625000Entrectinib0.3614186.7&lt;0.220000.220000.41340171261.7

Citation Format: Alexander Drilon, Dayong Zhai, Wei Deng, Xin Zhang, Dong Lee, Evan Rogers, Jeffrey Whitten, Zhongdong Huang, Armin Graber, Juliet Liu, Shanna Stopatschinskaja, J. Jean Cui, Dong-Wan Kim, Byoung Chul Cho, Robert C. Doebele, Sai-Hong Ignatius Ou, Jeeyun Lee, Alice T. Shaw. Repotrectinib, a next generation TRK inhibitor, overcomes TRK resistance mutations including solvent front, gatekeeper and compound mutations [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 442.

Abstract 1321: TPX-0022, a polypharmacology inhibitor of MET/CSF1R/SRC for treatment of cancers with abnormal HGF/MET signaling

Aberrant activation of the HGF/MET pathway has frequently been found in human cancers via MET mutation, gene amplification and translocation, as well as HGF paracrine or autocrine upregulation. The abnormal HGF/MET signaling not only acts as an oncogenic driver but also confers resistance to many cancer therapies, such as EGFR targeted therapy in NSCLC. One key downstream effector for activated MET is SRC, which is also involved in malignancy formation, tumor metastasis and drug resistance. In the tumor microenvironment, CSF1R plays an important role in regulation of tumor associated macrophages, which promote tumor progression and angiogenesis. Therefore, the polypharmacological inhibition of MET/SRC/CSF1R has great potential for more effectively targeting cancers with abnormal HGF/MET signaling via targeting both tumor intrinsic signaling and the tumor microenvironment. TPX-0022, a novel macrocyclic compound, has been designed and optimized to inhibit MET/CSF1R/SRC with enzymatic kinase inhibition IC50s of 0.14, 0.76 and 0.12 nM, respectively. TPX-0022 potently inhibited cell proliferation of the MET-amplified MKN-45 and SNU-5 gastric cancer cells, with IC50s &lt;0.2 nM, which ranked TPX-0022 as one of the most potent MET inhibitors. TPX-0022 caused suppression of MET auto-phosphorylation at an IC50 of approximately 0.3 nM in MKN-45 cell line. TPX-0022 also potently inhibited the phosphorylation of MET downstream signaling effectors, including AKT, ERK, STAT3 and PLCγ2 in a dose-dependent manner. In the cancer cell line- and patient-derived xenograft tumor models from gastric, lung and liver cancers harboring MET amplification or MET exon14 skipping mutations, TPX-0022 caused dramatic tumor regression and tumor growth inhibition, without overt abnormality and body weight loss in treated mice. Furthermore, the tumor inhibitory effect was associated with drastic inhibition of MET activity. Overall, TPX-0022 is a novel and potent MET inhibitor and has demonstrated desirable drug-like properties, a good preclinical safety profiles, that warrants further clinical development and an IND submission is currently planned.

Citation Format: Dayong Zhai, Evan Rogers, Wei Deng, Xin Zhang, Dong Lee, Jane Ung, Han Zhang, Jing Liu, Yuelie Lu, John Huang, Armin Graber, Zach Zimmerman, John Lim, Jeffrey Whitten, J. Jean Cui. TPX-0022, a polypharmacology inhibitor of MET/CSF1R/SRC for treatment of cancers with abnormal HGF/MET signaling [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1321.

Repotrectinib (TPX-0005) Is a Next-Generation ROS1/TRK/ALK Inhibitor That Potently Inhibits ROS1/TRK/ALK Solvent- Front Mutations

The use of tyrosine kinase inhibitors (TKI) with activity against ALK, ROS1, or TRKA-C can result in significant clinical benefit in patients with diverse tumors harboring ALK, ROS1, or NTRK1-3 rearrangements; however, resistance invariably develops. The emergence of on-target kinase domain mutations represents a major mechanism of acquired resistance. Solvent-front substitutions such as ALK^G1202R, ROS1^G2032R or ROS1^D2033N, TRKA^G595R, and TRKC^G623R are among the most recalcitrant of these mechanisms. Repotrectinib (TPX-0005) is a rationally designed, low-molecular-weight, macrocyclic TKI that is selective and highly potent against ROS1, TRKA-C, and ALK. Importantly, repotrectinib exhibits activity against a variety of solvent-front substitutions in vitro and in vivo As clinical proof of concept, in an ongoing first-in-human phase I/II trial, repotrectinib achieved confirmed responses in patients with ROS1 or NTRK3 fusion-positive cancers who had relapsed on earlier-generation TKIs due to ROS1 or TRKC solvent-front substitution-mediated resistance.Significance: Repotrectinib (TPX-0005), a next-generation ROS1, pan-TRK, and ALK TKI, overcomes resistance due to acquired solvent-front mutations involving ROS1, NTRK1-3, and ALK Repotrectinib may represent an effective therapeutic option for patients with ROS1-, NTRK1-3-, or ALK-rearranged malignancies who have progressed on earlier-generation TKIs. Cancer Discov; 8(10); 1227-36. ©2018 AACR. This article is highlighted in the In This Issue feature, p. 1195.

Discovery of Allosteric, Potent, Subtype Selective, and Peripherally Restricted TrkA Kinase Inhibitors

Tropomyosin receptor kinases (TrkA, TrkB, TrkC) are activated by hormones of the neurotrophin family: nerve growth factor (NGF), brain derived neurotrophic factor (BDNF), neurotrophin 3 (NT3), and neurotrophin 4 (NT4). Moreover, the NGF antibody tanezumab has provided clinical proof of concept for inhibition of the TrkA kinase pathway in pain leading to significant interest in the development of small molecule inhibitors of TrkA. However, achieving TrkA subtype selectivity over TrkB and TrkC via a Type I and Type II inhibitor binding mode has proven challenging and Type III or Type IV allosteric inhibitors may present a more promising selectivity design approach. Furthermore, TrkA inhibitors with minimal brain availability are required to deliver an appropriate safety profile. Herein, we describe the discovery of a highly potent, subtype selective, peripherally restricted, efficacious, and well-tolerated series of allosteric TrkA inhibitors that culminated in the delivery of candidate quality compound 23.

Abstract B186: TPX-0005, a polypharmacology inhibitor, overcomes ALK treatment resistance from acquired mutations, bypass signaling, and EMT

ALK kinase inhibitors have achieved tremendous success in the treatment of lung cancer patients with abnormal ALK gene. However, the emergence of drug resistance limits their long-term clinical applications. The mechanisms of resistance often include gene amplification, acquired mutations, bypass signaling, and epithelial-mesenchymal transition (EMT). More than 10 different mutations have been identified in clinic, and recently the compound mutations represent new challenges after multiple ALK inhibitor treatments. The bypass and EMT-based resistance mechanisms constitute a large portion of the resistant patient population. None of the current ALK inhibitors can overcome bypass or EMT-based resistance when applied as a single-agent therapy. Therefore, a different strategy needs to be deployed for the design of new-generation ALK inhibitors to overcome multi-resistance mechanisms simultaneously. TPX-0005, a novel three-dimensional macrocycle with a much smaller size than current ALK inhibitors in the clinic, was designed to overcome clinical resistance mutations systematically. TPX-0005 potently inhibited both wild type and mutant ALK fusion proteins including gatekeeper, solvent front, and compound mutations as shown in the table. In addition to its primary targets, TPX-0005 is also a potent SRC/FAK inhibitor with IC50s of 70-80 nM in H2228 cells. H2228 lung cancer cell line, endogenously expressing EML4-ALKv3 protein, is refractory to crizotinib and ceritinib. The upregulation of multiple RTKs including EGFR and IGFR, as well as cancer stem cell marker CD44 and mesenchymal marker vimentin, is believed to induce the primary resistance to selective ALK inhibitors. Inhibition of SRC/FAK kinases will modulate bypass RTK expression, cancer stem-like properties, and EMT to restore the sensitivity to ALK inhibition. TPX-0005 dose-dependently downregulated EGFR, CD44, and vimentin expression levels via SRC/FAK inhibition. TPX-0005 effectively inhibited cancer cell migration in wound healing assays, and induced dramatic tumor regression in human PDX NSCLC tumor model. In addition, TPX-0005 significantly extended survival time in mouse H2228 orthotopic brain tumor model. Overall, TPX-0005 exerts unprecedented polypharmacology profile for combating multiple resistance mechanisms. A phase 1/2 clinical trial of TPX-0005 is actively being pursued (NCT03093116). EML4-ALK Ba/F3 Cell Proliferation Assay IC50 (nM)InhibitorWTG1202RL1196ML1198F/C1156YL1198F/G1202RL1198F/L1196MTPX-000517.820.5501.10.234.8Crizotinib74.8359.47132243.7350.7Ceritinib2.138861123476.81794Alectinib18.950713115813691249Brigatinib11.8399131181187341Lorlatinib0.7ND1889131.61169

ND: not determined

Citation Format: Dayong Zhai, Wei Deng, Evan Rogers, Zhongdong Huang, Jeffrey Whitten, John Lim, Yishan Li, J. Jean Cui. TPX-0005, a polypharmacology inhibitor, overcomes ALK treatment resistance from acquired mutations, bypass signaling, and EMT [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B186.

Abstract B185: TPX-0005, a supreme ROS1 inhibitor, overcomes crizotinib-resistant ROS1 mutations including solvent front mutation G2032R and gatekeeper mutation L2026M

The fusion kinases of ROS1 and ALK have been identified as oncogene drivers in small portions of many malignancies, especially in non-small cell lung cancer (NSCLC). ALK/ROS1/MET inhibitor crizotinib has been approved by the US Food and Drug Administration for the treatment of ALK or ROS1-positive non-small cell lung cancer in 2011 and 2016, respectively. The emergence of drug resistance presents a major issue for targeted therapy. Although ceritinib, alectinib, and brigatinib have been approved for crizotinib-refractory ALK+ patients with NSCLC, treatment options for patients with ROS1+ NSCLC are limited, especially for crizotinib-refractory patients. Ceritinib and entectinib demonstrated clinical efficacy only in crizotinib-naïve ROS1+ patients. The most common resistance mechanisms to crizotinib treatment in ROS1+ NSCLC is the solvent front mutation ROS1 G2032R and gatekeeper mutation ROS1 L2026M. TPX-0005, a novel three-dimensional macrocycle with a much smaller size than current ROS1 inhibitors in the clinic, was designed to overcome clinical resistance mutations systematically. TPX-0005 potently inhibited both wild type and mutant ROS1s including solvent front mutations and gatekeeper mutations. TPX-0005 showed pico-molar activity against ROS1 kinase (IC50 0.076 nM) in Reaction Biology kinase assay. The comparison of TPX-0005 with other ROS1 inhibitors in Ba/F3 cell proliferation assays is presented in the table. In the xenograft tumor model studies, TPX-0005 dramatically caused tumor regression in the tumors carrying WT or solvent-front mutated ROS1 fusion gene. Overall, TPX-0005 demonstrated desired drug-like properties, good safety profile, and is a supreme ROS1 inhibitor against WT and various mutated ROS1s. A phase 1/2 clinical trial of TPX-0005 is actively being pursued (NCT03093116). CD74-ROS1 Ba/F3 Cell Proliferation Assay IC50 (nM)InhibitorWTG2032RD2033NL2026MS1986FS1986YTPX-0005&lt;0.28.40.210&lt;0.2&lt;0.2Crizotinib9.71402139606.420.919Lorlatinib0.5262.42.4ND0.30.3Entrectinib25.42404ND2026NDNDCeritinib131.92000NDND14.226.9Brigatinib28.61385167.1211527.724.6Cabozantinib1.060.70.129.1NDND

ND: not determined.

Citation Format: J. Jean Cui, Dayong Zhai, Wei Deng, Evan Rogers, Zhongdong Huang, Jeffrey Whitten, John Lim, Yishan Li. TPX-0005, a supreme ROS1 inhibitor, overcomes crizotinib-resistant ROS1 mutations including solvent front mutation G2032R and gatekeeper mutation L2026M [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B185.

Abstract B184: TPX-0005, a highly potent TRK inhibitor, effectively overcomes clinical-resistance TRK mutations including solvent front mutants TRKA G595R, TRKB G639R, and TRKC G623R

The tropomyosin receptor kinases (TRKs), including TRKA/B/C encoded by NTRK1/2/3 genes, are high-affinity receptors for neurotrophins. Oncogenic rearrangement of NTRK1, NTRK2, and NTRK3 have been identified in many solid malignancies. The use of TRK inhibitors entrectinib and larotrectinib has led to clinical benefit in patients with solid malignancies harboring oncogenic NTRK fusions. Similar to ALK and ROS1 inhibitor treatment, the solvent front mutations TRKA G595R and TRKC G623R (both analog to ALK G1202R) were reported in clinic from treatment-resistant patients. A new generation of TRK inhibitors targeting both wild type and mutated TRKs is highly needed for effectively treating patients harboring fusion TRKs. TPX-0005, a novel three-dimensional macrocycle with a much smaller size than current TRK inhibitors in the clinic, was designed to overcome clinical resistance mutations systematically. TPX-0005 potently inhibited both wild type and mutant TRKs including solvent front mutations. TPX-0005 showed pico-molar activity against TRK kinases (IC50s 0.83 nM, 0.05 nM, and 0.10 nM for TRKA/B/C, respectively) in Reaction Biology kinase assay. TPX-0005 is the most potent TRK inhibitor in clinic and effectively overcomes clinical resistance TRK mutations as shown in the table in cell proliferation assays. It was recently reported that LOXO-195 inhibited the phosphorylation of TRKA and ERK kinases in NIH3T3 cell line expressing ΔTRKA G595R or ETV6-TRKC G623R with IC50s of 7 nM and 45.5 nM, respectively. TPX-0005 is more than 10-fold more potent than LOXO-195. In the xenograft tumor model studies including human PDX model, TPX-0005 dramatically caused tumor regression in the tumors carrying WT or solvent-front mutated TRK fusion gene. Overall, TPX-0005 demonstrated desired drug-like properties, good safety profile, and is a supreme TRK inhibitor against WT and mutated TRKs. A phase 1/2 clinical trial of TPX-0005 is actively being pursued (NCT03093116). KM-12 IC50 (nM)Ba/F3 Cell Proliferation Assay IC50 (nM)InhibitorTPM3-TRKAWTLMNA-TRKA WTLMNA-TRKA G595RETV6-TRKB WTETV6-TRKB G639RETV6-TRKC WTETV6-TRKC G623RTPX-0005&lt;0.2&lt;0.20.4&lt;0.20.6&lt;0.23Entrectinib9.20.3705&lt;0.513840.61000Larotrectinib12.33.5102410.9300010.21500

Citation Format: J. Jean Cui, Dayong Zhai, Wei Deng, Evan Rogers, Zhongdong Huang, Jeffrey Whitten, John lim, Yishan Li. TPX-0005, a highly potent TRK inhibitor, effectively overcomes clinical-resistance TRK mutations including solvent front mutants TRKA G595R, TRKB G639R, and TRKC G623R [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B184.

Abstract 3161: TPX-0005, an ALK/ROS1/TRK inhibitor, overcomes multiple resistance mechanisms by targeting SRC/FAK signaling

ALK, ROS1, and TRK inhibitors have achieved marked efficacy in treating cancer patients expressing abnormal ALK, ROS1 or NTRK genes. However, the initial success of these therapies is rapidly overshadowed with the development of acquired resistance. In addition, approximately 30-40% of ALK + or ROS1+ NSCLC patients fail to respond to initial crizotinib treatment, representing intrinsic resistance. Target gene amplification, acquired resistance mutations, bypass signaling, epithelial-mesenchymal transition (EMT) and metastasis are the common resistance mechanisms. None of the current ALK, ROS1 or TRK inhibitors can overcome bypass or EMT-based resistance when applied as a single agent therapy. TPX-0005 is a potent kinase inhibitor against WT and mutated ALK, ROS1 and TRK family kinases, especially the clinically significant solvent front mutations. At clinically relevant concentrations, TPX-0005 also inhibits JAK2, SRC and FAK that are important targets in modulating multiple resistance mechanisms. H2228 lung cancer cell line endogenously expresses EML4-ALK v3 and was reported to be resistant to ALK inhibitor TAE684. Upregulation of the bypass signaling kinase EGFR, EMT marker vimentin, and cancer stem-like marker CD44 was reported in H2228 cells, likely leading to intrinsic resistance to ALK inhibitors. In the anti-proliferation assay, both crizotinib and ceritinib were resistant in H2228 cells with IC50 values around 1000 nM, however, TPX-0005 was able to overcome the intrinsic resistance with an IC50 of 100 nM. In H2228 cells, TPX-0005 suppressed the phosphorylation of SRC, FAK and paxillin with IC50 values in a range of 80-100 nM, and downregulated the expression of EGFR, CD44, and vimentin with IC50 values around 100 nM. In addition, TPX-0005 inhibited the phosphorylation of the oncogenic transcription/translation factor YB-1 with an IC50 value around 100 nM in H2228 cells. YB-1 is involved in many aspects of gene expression control that lead to tumor cell growth and drug resistance, including modulation of EGFR upregulation, EMT, and cancer stemness. Therefore, it was postulated that inhibition of SRC/FAK by TPX-0005 suppressed the phosphorylation of YB-1, leading to the downregulation of EGFR, CD44 and vimentin, and eventually to anti-proliferation effect on H2228 cells. TPX-0005 demonstrated an in vitro anti-metastatic activity by inhibiting cell migration in both H2228 cells and HT1080 human fibrosarcoma cells. Taken together, the potent kinase inhibitory activities against SRC/FAK signaling provide a unique polypharmacology profile to TPX-0005 for combatting multiple resistance mechanisms simultaneously, including a broad spectrum of acquired mutations, bypass signaling, EMT, cancer stemness, and metastasis.

Citation Format: Dayong Zhai, Wei Deng, John Huang, Evan Rogers, J. Jean Cui. TPX-0005, an ALK/ROS1/TRK inhibitor, overcomes multiple resistance mechanisms by targeting SRC/FAK signaling [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3161. doi:10.1158/1538-7445.AM2017-3161

Identification of a novel T1151K ALK mutation in a patient with ALK-rearranged NSCLC with prior exposure to crizotinib and ceritinib

Patients with anaplastic lymphoma kinase (ALK)-rearranged non-small cell lung cancer (NSCLC) derive significant clinic benefit from treatment with ALK inhibitors. Crizotinib was the first approved tyrosine kinase inhibitor (TKI) for this distinct molecular subset of NSCLC. Disease progression on TKI inevitably arises secondary to diverse resistance mechanisms among which emergence of secondary ALK mutations is one of many ways in which tumor cells have adapted to survive. Therefore there is a clinical imperative to identify acquired ALK mutations via repeat tissue biopsy if clinically feasible. If such is present, switching to a different TKI with known clinical activities against the emergent resistance mutation (s) may pose a viable treatment option. Here we report for the first time a novel ALK T1151K mutation in a patient with metastatic ALK-rearranged NSCLC who progressed on crizotinib and then ceritinib. The co-crystal structure of ceritinib/ALK demonstrates a strong interaction between ceritinib and the P-loop which is facilitated by T1151 on the β3 sheet, a feature not present in the alectinib/ALK or lorlatinib/ALK co-crystal structure. It is predicated that the T1151K mutation weakens these interactions leading to drug resistance, or causes conformational changes of the ALK catalytic domain resulting in higher affinity for ATP and therefore diminished inhibitor binding. We conclude that the T1151K ALK mutation confers resistance to ceritinib, which may be rescued by alectinib or lorlatinib as evidenced by this clinical narrative.

Proacrosin activation mechanisms in capacitated and frozen-thawed boar spermatozoa

The main objective of the current study was to explore the different activation mechanisms of capacitation and freeze-thawed spermatozoa. Using SDS-PAGE and Western blotting, the conversion process of boar proacrosin during freeze-thawing and capacitation of spermatozoa was analyzed. The results revealed that capacitated spermatozoa exhibited a greater fluorescence area than that of the freeze-thawed spermatozoa, which were smaller than those of the fresh group. Fresh spermatozoa displayed 45- and 35- kDa protein bands, while those of freeze-thawed andcapacitated spermatozoa displayed 45-, 35- and 28-kDa bands. In summary, these data indicate that proacrosin is activated, thus becoming α- and β-acrosins and a 28-kDa protein during capacitation and freeze-thawing.