Trotabresib, an oral potent bromodomain and extraterminal inhibitor, in patients with high-grade gliomas: A phase I, "window-of-opportunity" study

BACKGROUND

The bromodomain and extraterminal protein (BET) inhibitor trotabresib has demonstrated antitumor activity in patients with advanced solid tumors, including high-grade gliomas. CC-90010-GBM-001 (NCT04047303) is a phase I study investigating the pharmacokinetics, pharmacodynamics, and CNS penetration of trotabresib in patients with recurrent high-grade gliomas scheduled for salvage resection.

METHODS

Patients received trotabresib 30 mg/day on days 1-4 before surgery, followed by maintenance trotabresib 45 mg/day 4 days on/24 days off after surgery. Primary endpoints were plasma pharmacokinetics and trotabresib concentrations in resected tissue. Secondary and exploratory endpoints included safety, pharmacodynamics, and antitumor activity.

RESULTS

Twenty patients received preoperative trotabresib and underwent resection with no delays or cancelations of surgery; 16 patients received maintenance trotabresib after recovery from surgery. Trotabresib plasma pharmacokinetics were consistent with previous data. Mean trotabresib brain tumor tissue:plasma ratio was 0.84 (estimated unbound partition coefficient [KPUU] 0.37), and modulation of pharmacodynamic markers was observed in blood and brain tumor tissue. Trotabresib was well tolerated; the most frequent grade 3/4 treatment-related adverse event during maintenance treatment was thrombocytopenia (5/16 patients). Six-month progression-free survival was 12%. Two patients remain on treatment with stable disease at cycles 25 and 30.

CONCLUSIONS

Trotabresib penetrates the blood-brain-tumor barrier in patients with recurrent high-grade glioma and demonstrates target engagement in resected tumor tissue. Plasma pharmacokinetics, blood pharmacodynamics, and safety were comparable with previous results for trotabresib in patients with advanced solid tumors. Investigation of adjuvant trotabresib + temozolomide and concomitant trotabresib + temozolomide + radiotherapy in patients with newly diagnosed glioblastoma is ongoing (NCT04324840).

CTNI-21. TROTABRESIB (CC-90010) IN COMBINATION WITH CONCOMITANT TEMOZOLOMIDE PLUS RADIOTHERAPY AND ADJUVANT TEMOZOLOMIDE IN PATIENTS WITH NEWLY DIAGNOSED GLIOBLASTOMA: UPDATED RESULTS FROM A PHASE 1B/2 STUDY

Trotabresib, a novel bromodomain and extraterminal protein inhibitor, has demonstrated antitumor activity and blood–brain barrier penetration in patients with high-grade gliomas, and enhanced the antiproliferative effects of temozolomide in preclinical models. CC-90010-GBM-002 (NCT04324840) is a phase 1b/2 study investigating the addition of trotabresib to standard-of-care (SOC) concomitant temozolomide plus radiotherapy and adjuvant temozolomide, followed by maintenance trotabresib, in patients with newly diagnosed glioblastoma. The design of the dose escalation (part A) has been described previously (Vieito M, et al. SNO 2021. Abstract CTNI-51). Primary objectives of part A were to establish the safety, tolerability, and maximum tolerated dose/recommended phase 2 dose (RP2D) of trotabresib. In part A, addition of trotabresib to SOC was safe and well tolerated in the concomitant (N = 14) and adjuvant (N = 18) cohorts; the most frequent grade 3/4 treatment-related adverse event was thrombocytopenia (7/14 and 9/18 patients, respectively). The RP2D for trotabresib was 30 mg/day 4 days on/24 days off in both settings. At data cutoff (February 20, 2022), median duration of treatment was 34 weeks (concomitant cohort) and 33 weeks (adjuvant cohort); progression-free survival data are not yet mature. Trotabresib plasma pharmacokinetics and pharmacodynamics were consistent with monotherapy. At last follow-up, 6 and 5 patients remained on treatment in the concomitant and adjuvant dose-escalation cohorts, respectively, including 1 patient in cycle 20 with ongoing complete response. The ongoing randomized phase 2 dose expansion (part B; planned N = 162) is comparing concomitant trotabresib at the RP2D + SOC followed by adjuvant trotabresib at the RP2D + SOC, followed by maintenance trotabresib 45 mg/day 4 days on/24 days off, versus SOC alone in patients with newly diagnosed IDH–wild-type glioblastoma. Key objectives are to compare progression-free and overall survival, safety, and tolerability. Longer follow-up from part A and the first disclosure of data from part B will be presented.

Trotabresib (CC90010) in combination with adjuvant temozolomide or concomitant temozolomide plus radiotherapy in patients with newly diagnosed glioblastoma

Background

Standard-of-care treatment for newly diagnosed glioblastoma (ndGBM), consisting of surgery followed by radiotherapy (RT) and temozolomide (TMZ), has improved outcomes compared with RT alone; however, prognosis remains poor. Trotabresib, a novel bromodomain and extraterminal inhibitor, has demonstrated antitumor activity in patients with high-grade gliomas.

Methods

In this phase Ib, dose-escalation study (NCT04324840), we investigated trotabresib 15, 30, and 45 mg combined with TMZ in the adjuvant setting and trotabresib 15 and 30 mg combined with TMZ+RT in the concomitant setting in patients with ndGBM. Primary endpoints were to determine safety, tolerability, maximum tolerated dose, and/or recommended phase II dose (RP2D) of trotabresib. Secondary endpoints were assessment of preliminary efficacy and pharmacokinetics. Pharmacodynamics were investigated as an exploratory endpoint.

Results

The adjuvant and concomitant cohorts enrolled 18 and 14 patients, respectively. Trotabresib in combination with TMZ or TMZ+RT was well tolerated; most treatment-related adverse events were mild or moderate. Trotabresib pharmacokinetics and pharmacodynamics in both settings were consistent with previous data for trotabresib monotherapy. The RP2D of trotabresib was selected as 30 mg 4 days on/24 days off in both settings. At last follow-up, 5 (28%) and 6 (43%) patients remain on treatment in the adjuvant and concomitant settings, respectively, with 1 patient in the adjuvant cohort achieving complete response.

Conclusions

Trotabresib combined with TMZ in the adjuvant setting and with TMZ+RT in the concomitant setting was safe and well tolerated in patients with ndGBM, with encouraging treatment durations. Trotabresib 30 mg was established as the RP2D in both settings.

CTNI-16. TROTABRESIB (CC-90010, BMS-986378), A REVERSIBLE, POTENT ORAL BROMODOMAIN AND EXTRATERMINAL INHIBITOR (BETi) IN PATIENTS WITH HIGH-GRADE GLIOMAS: A PHASE 1 OPEN-LABEL ‘WINDOW OF OPPORTUNITY’ STUDY

Trotabresib is a potent, reversible oral BETi with antitumor activity in patients with advanced malignancies (Moreno et al. ESMO 2020. Abstract 5270). The CC-90010-GBM-001 study (NCT04047303) enrolled patients with progressive or recurrent astrocytoma or recurrent glioblastoma scheduled for salvage resection. Patients were treated with trotabresib 30 mg daily for 4 days before surgery, then trotabresib 45 mg daily 4 days on/24 days off after recovery. Primary objectives were trotabresib tumor tissue concentration and plasma pharmacokinetics (PK). Secondary and exploratory objectives included safety, antitumor activity, cerebrospinal fluid concentration, and pharmacodynamics (PD). Twenty patients were enrolled; blood PK, blood PD, and tumor PD data were available for 14, 12, and 11 patients, respectively. Geometric mean peak trotabresib plasma concentration on day 4 was 1.92 μM; median time to peak concentration was 1.5 hours. At the time of resection, geometric mean trotabresib concentrations in plasma and brain tumor tissue were 1.01 and 0.68 μM, respectively. Blood CCR1 mRNA was reduced ≥ 50% from baseline after dose 4. Blood HEXIM1 mRNA increased at 72–96 hours following first dose, and at the time of surgery the percentage increase was related to plasma trotabresib concentration. Tumor HEXIM1 RNA increased in 10 of 11 patients. Eighteen patients (90%) had ≥ 1 treatment-related adverse event (TRAE). Nine patients (45%) had grade 3/4 TRAEs, most frequently thrombocytopenia (5 patients [25%]). Only 1 patient had serious TRAEs (hemiparesis and lethargy). Two patients died of intracranial hemorrhage unrelated to study drug. Of 16 patients evaluable for antitumor response, 7 had stable disease per RANO criteria, with 3 ongoing beyond data cutoff at cycles 4–11. Median progression-free survival was 1.9 months (95% CI, 1.4–3.3). Overall, trotabresib showed good tumor tissue penetration, with PD signals of response, and was well tolerated. A study of trotabresib + temozolomide in first-line glioblastoma is ongoing (NCT04324840).

CTNI-51. ADJUVANT TROTABRESIB, A REVERSIBLE POTENT BROMODOMAIN AND EXTRATERMINAL INHIBITOR, PLUS TEMOZOLOMIDE IN PATIENTS WITH NEWLY DIAGNOSED GLIOBLASTOMA: INTERIM RESULTS FROM A PHASE 1B DOSE-FINDING STUDY

Trotabresib (CC-90010) demonstrated antitumor activity as monotherapy in patients with advanced malignancies (Moreno et al. ESMO 2020. Abstract 5270) and enhanced the antiproliferative effects of temozolomide in preclinical studies. CC-90010-GBM-002 (NCT04324840) is a phase 1B dose-finding study investigating standard-of-care temozolomide + radiotherapy followed by adjuvant trotabresib + temozolomide or concomitant trotabresib + temozolomide + radiotherapy followed by adjuvant trotabresib + temozolomide, post-resection, in patients with newly diagnosed glioblastoma. We present interim results for adjuvant trotabresib + temozolomide. Patients received trotabresib 15, 30, or 45 mg daily (4 days on/24 days off) + temozolomide administered per label for 6 cycles, followed by trotabresib 45 mg monotherapy daily (4 days on/24 days off). Primary objectives are to establish the safety, maximum tolerated dose (MTD), and recommended phase 2 dose (RP2D) of trotabresib. Preliminary efficacy, pharmacokinetics, and pharmacodynamics are also being investigated. Of 13 patients enrolled, 5, 6, and 2 received trotabresib 15, 30, and 45 mg, respectively, plus temozolomide. Grade 3/4 treatment-related adverse events were reported in 2, 4, and 1 patients receiving trotabresib 15, 30, and 45 mg, respectively. MTD and RP2D are not yet reached; dose limiting toxicity (grade 4 thrombocytopenia) was reported in 1 patient in the 30-mg group. Of 10 evaluable patients, 1 had complete response and 7 had stable disease per RANO criteria. Trotabresib exposure increased proportionally with dose. Day 4 time to peak trotabresib concentration was 0.5–2.0 hours; mean terminal half life was 60–70 hours. Day 4 blood CCR1 RNA 2–4 hours post-dose was downregulated below baseline in the 15-mg group and ≥ 50% in the 30-mg group. Adjuvant trotabresib + temozolomide appears well tolerated, with promising preliminary efficacy. Treatment was ongoing at data cutoff in 9 patients in the adjuvant cohort; enrollment is continuing in the adjuvant and concomitant therapy dose-escalation cohorts.

Wetting properties of porous high temperature polymer electrolyte fuel cells materials with phosphoric acid

The influence of phosphoric acid temperature and concentration on the wetting behavior of porous high temperature polymer electrolyte fuel cell materials is investigated.

Serum free light chain ratio, total kappa/lambda ratio, and immunofixation results are not prognostic factors after stem cell transplantation for newly diagnosed multiple myeloma

BACKGROUND

The prognostic value of changes in paraprotein markers after stem cell transplantation is unknown. We evaluated disease response using serum immunofixation (s-IFIX), total kappa and lambda ratio (KLR), and free light chain (FLC) ratio in myeloma patients who underwent autologous or autologous plus allogeneic stem cell transplantation.

METHODS

We studied s-IFIX, KLR, and FLC ratio in sera from 203 patients, 3 months after transplantation. We evaluated overall and event-free survival (OS and EFS, interval between date of study enrollment and date of death from any cause or date of progression, relapse, or death from any cause, respectively) by the Kaplan-Meier method.

RESULTS

Of the 203 patients, 51 were negative by s-IFIX, 99 reached a normal KLR, and 92 had a normal FLC ratio. Of the 51 patients with negative s-IFIX, 40 (78%) also had a normal FLC ratio. The median duration of OS was 54.3 months, and the median EFS was 19.5 months. None of the measured paraprotein parameters showed an association with OS. Only a normal KLR was associated with prolonged EFS (P = 0.016). Even a negative s-IFIX associated with a normal FLC ratio did not show a significant difference in terms of EFS and OS.

CONCLUSIONS

Our analysis with a small cohort of patients did not show a significant impact of achieving complete response (CR) or stringent CR on patient survival.

Clinical evaluation of percent free prostate-specific antigen using the AxSYM system in the best analytical scenario

OBJECTIVE

Percent free prostate-specific antigen (PSA) is a promising tool for prostate cancer (CaP) diagnosis. However, its diagnostic performances have not yet been established. The present study was carried out with the aim of evaluating percent free PSA in the most favourable analytical conditions.

MATERIALS AND METHODS

Eighty-eight patients affected by newly diagnosed, untreated, primary CaP, and 169 cases with biopsy-confirmed, untreated, benign prostatic hypertrophy (BPH) were prospectively enrolled. Abbott AxSYM total and free PSA were measured by the same technician using the same instrument and the same reagent batch.

RESULTS

Percent free PSA was more effective than total PSA in differential diagnosis between CaP and BPH in every evaluated dose range of total PSA. In cases with total PSA >4 microg/l, percent free PSA could have reduced by about 50% the rate of unnecessary biopsies with a probably still acceptable 93% cancer detection rate. The likelihood of CaP after the determination of percent free PSA was in fact higher than 50% using cut-off points which provide low sensitivity values (i.e. 58% in men aged 50-59 years).

CONCLUSIONS

Percent free PSA is superior to total PSA in distinguishing primary CaP from BPH in patients with total PSA between 2 and 30 microg/l and in reducing the rate of unnecessary biopsies in men with total PSA higher than 4 microg/l. However, percent free PSA should be cautiously interpreted in decision making in individual patients since post-test probability is relatively low in men aged 50-70 years.

Detection of different estrogen receptor forms in breast cancer cytosol by enzyme immunoassay

Estrogen receptors (ER) are routinely measured in tissue extracts from breast cancer using a radioligand binding assay (RBA) and an enzyme immunoassay (EIA). Although good correlation was found between the two methods, they are expected to measure, at least in part, different ER amounts in individual samples, because the RBA should detect unfilled ER only, whereas EIA should recognize both unfilled receptors and those filled by endogenous estrogens. The purpose of the present investigation was to evaluate if ER-EIA mainly detects ER filled by endogenous estrogens when using an estrogen-free buffer to dilute cytosol samples. Indeed, the commercially available EIA assay kit (ER-EIA; Abbott) is equipped with a sample dilution buffer containing a high concentration of 17beta-estradiol which should allow for the saturation of all the ERs. ER was measured in 57 cytosol samples from primary breast cancer with RBA and ER-EIA. In the latter case, samples were diluted using both the estradiol-rich dilution buffer of the kit and an estrogen-free low salt phosphate buffer. RBA and ER-EIA showed tightly correlated results. However, ER-EIA detected higher ER levels than RBA in the majority of cases. Results obtained by low salt ER-EIA were also correlated to both RBA and ER-EIA, showing, however, lower ER concentrations. ER levels measured by ER-EIA were not significantly different from the sum of ER concentrations found by RBA and low salt ER-EIA. These findings suggest that ER-EIA detects ER only in the conformational status that is achieved after saturation by estrogens. These findings were confirmed by sedimentation shift experiments, which showed that the monoclonal antibody D547 used in the kit binds ER in the occupied form only. This leads to the conclusion that ER-EIA detects functioning (in terms of binding with estradiol) ERs. From the present investigation, we suggest that it is possible and probably worthwhile to optimize the EIA method by using different buffers to measure: (a) the total number of ERs capable of binding estradiol; (b) the ER filled by endogenous estrogens; and (c) by difference, the unfilled ER concentrations.