The safety and efficacy of PEN-221 somatostatin analog (SSA)-DM1 conjugate in patients (PTS) with advanced GI mid-gut neuroendocrine tumor (NET): Phase 2 results

4110

Background: PEN-221 is a small molecule drug conjugate composed of a SSTR2 binding somatostatin analog linked to the toxin DM1. PEN-221-001 was a study which assessed the safety, tolerability, pharmacokinetics (PK), and preliminary efficacy of PEN-221 in well differentiated neuroendocrine tumors (NETs) and small cell lung cancer. Here we present the efficacy outcomes for patients enrolled in the GI mid-gut cohort and the safety data for the entire study. Methods: Pts with advanced, SSTR2+ (by imaging) GI mid-gut NETs were enrolled in this cohort of the study. The primary objective was to determine the safety and efficacy of PEN-221 given intravenously, every (q) 3 weeks in patients with documented radiographic progression within the 6 months prior to enrollment. Patients previously treatment with cytotoxic chemotherapy were excluded. Preliminary efficacy was assessed using RECIST 1.1. A clinically meaningful efficacy result was defined as a Clinical Benefit Rate (CBR) > 75% and a median progression-free survival (mPFS) > 8 months. Results: 32 patients (17M/15F) were enrolled between January 2018 to June 2020 and the data cut-off for this report is July 31, 2020. The first nine patients were treated at the phase 1 determined Maximum Tolerated Dose of 18 mg. After review of the safety, tolerability, and PK data from these pts, the regimen was amended to 8.8 mg/m2 for all subsequent pts to achieve more uniform exposures (AUC) across all pts and reduce toxicity in pts with lower body-surface areas (BSA). The mean number of cycles received by pts in this cohort was 7 (range 1-18), with 5 pts still on treatment at time of data lock. PEN-221 was well tolerated in all pts at the dose of 8.8 mg/m2. The most frequent (≥20% pts) PEN-221 related adverse events of any grade were fatigue (39%), nausea (38%), diarrhea (35%), decreased appetite (30%), infusion reaction (24%), AST/ALT/Alk Phos increase (24%), and peripheral neuropathy (21%). Only 14 (10%) of these events were grade 3 or greater. Grade 3 PEN-221 related adverse events which were reported in 2 or more pts included fatigue (7.6%), ALT/AST/Alk Phos increase (7.6%), and peripheral neuropathy (3%). PEN-221 plasma median t1/2 was ̃4.5 h, with exposures uniform using BSA based dosing. Of the 26 pts who were evaluable for response, 23 (88.5%) had stable disease (SD) reported as their best response with a CBR of 88.5%. Target lesion shrinkage was observed in 10 (38%) patients. The median PFS for this cohort was 9 months (CI 5 – 16.5 months). Tumor marker data (Neuron Specific Enolase, Chromogranin A, 5-Hydroxyindoleacetic Acid, and Circulating Tumor Cells) will also be presented. Conclusions: PEN-221 appears well tolerated at 8.8 mg/m2 q 3 weeks and has demonstrated efficacy exceeding its clinical efficacy goals with a CBR of 88.5% and a mPFS of 9 months. A randomized trial of PEN-221 in GI mid-gut NET patients is now in development. Clinical trial information: NCT02936323.

Pen-866, a miniature drug conjugate of a heat shock protein 90 (HSP90) ligand linked to SN38 for patients with advanced solid malignancies: Phase I and expansion cohort results

3515

Background: PEN-866 is a miniature drug conjugate which links a HSP90 binding small molecule to a SN-38 cytotoxic payload. HSP90 is highly expressed in advanced malignancies. PEN-866 targets and binds to activated tumor HSP90 protein, releases its cytotoxic payload, and results in complete tumor regressions in multiple xenograft models. This first-in-human study assessed safety, tolerability, pharmacokinetics (PK), and preliminary efficacy of PEN-866. Methods: Patients (pts) with progressive, advanced solid malignancies were enrolled in escalating cohorts of 2-9 pts. The primary objective was to determine the maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D) of PEN-866 given weekly (3 out of 4 weeks in a 28-day cycle). Results: 30 pts were treated in 8 cohorts (range 30-360 mg flat dosing or 150–200 mg/m2 BSA-based dosing). As of 9Jan20, the total median/mean exposure was 7.05/12.4 weeks. No dose limiting toxicities (DLTs) occurred in the first 4 cohorts (30-240 mg; 14 pts). In cohort 5 (360 mg), 1 of 3 pts had a DLT of grade (G) 3 transient diarrhea, and 2 other pts had G3 uncomplicated transient neutropenia. A change to BSA-based dosing was instituted for cohort 6 (175 mg/m2), on which no DLTs were observed, although 1 pt experienced G3 uncomplicated transient neutropenia. At 200 mg/m2, 2 of 5 pts experienced DLTs (G5 dehydration, G3 fatigue). The MTD and RP2D were determined to be 175 mg/m2. The most frequent (≥20% pts) related adverse events were nausea (50%), fatigue (43%), diarrhea (40%), vomiting (27%), and anemia (23%). PK was nonlinear. Plasma exposures increased greater than dose proportionally. Median t1/2 ~7 h. Cleaved SN38 never exceeded 3% of PEN-866 plasma AUC at all dose levels. Tissue PK confirmed tumor accumulation and retention of both the conjugate and released payload. As of 9Jan20, 26 pts were evaluable for response. 11 pts had stable disease at 8 weeks, of which 7 lasted 12–58 weeks. One pt with anal squamous cell carcinoma achieved a confirmed partial response. Decreased target lesion size was observed in 6 additional pts. Conclusions: PEN-866 was well tolerated and demonstrated preliminary evidence of antitumor activity. PEN-866 will be evaluated in Phase 2a expansion cohorts enrolling multiple solid tumors (NCT03221400). Clinical trial information: NCT03221400 .

Independent review of fatal interstitial lung disease (ILD) in TRIBUTE: paclitaxel + carboplatin ± erlotinib in advanced non-small cell lung cancer (NSCLC)

7071

Background: ILD is a rare but serious complication of EGFR tyrosine kinase inhibitor (TKI) therapy, fatal in about 1/3 of cases. The incidence, severity & risk factors for ILD remain poorly understood, but it is reported to be more common in Asian patients receiving gefitinib. Whether the risk of ILD with gefitinib exceeds that of erlotinib is unclear. Whether concurrent chemotherapy increases the risk of ILD is also unclear. Methods: This study was designed to determine the incidence of ILD leading to death in 1,059 TRIBUTE patients randomized to chemotherapy plus erlotinib or placebo (Herbst: JCO, 2005). A blinded review of fatal SAEs was performed by an independent 3 person panel comprised of a medical oncologist (DRG), radiologist (DS), and pulmonologist (KY) unassociated with the study. Fatal respiratory SAEs (41 met criteria) were assigned to 1 of 4 potential attributions: progressive NSCLC; concurrent illness; toxicities not related to study drug; or ILD. Each panel member first made an independent assignation based on case report forms/source documents; then each case was discussed jointly. If needed, consensus was reached by vote. Results: Fatal SAEs were reported in 80/1059 patients (7.6%): 53/526 patients on erlotinib (10.1%) & 27/533 on placebo (5.1%) (p = 0.002). Consensus assignation for 41 respiratory SAEs was as follows: NSCLC: 18 (44%), concurrent illness: 15 (37%), toxicities not related to study drug: 5 (12%), ILD: 3 (7%). There were no statistical differences in assignation by study arm. However, all 3 ILD cases occurred in the erlotinib arm (3/523; overall incidence 0.6%). Case details will be provided. Conclusions: 1) To our knowledge, this analysis of TRIBUTE is the only independent blinded assessment of respiratory SAEs & ILD related to an EGFR TKI (erlotinib) + chemotherapy. 2) Overall, there were 41 fatal respiratory SAEs (3.9%). Fatal ILD occurred in 0.6% of cases treated with the combination. Using estimates that 1/3 of EGFR TKI-induced ILD cases are fatal, the overall incidence in this study arm was likely around 1.5–2%, not inconsistent with prior reports of TKIs alone. 3) Further studies designed to better define the underlying pathophysiology and risk factors for ILD are needed.

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Phase II evaluation of 9-aminocamptothecin (9-AC, NSC #603071) in platinum-resistant ovarian and primary peritoneal carcinoma: A Gynecologic Oncology Group Study

OBJECTIVE

To estimate the antitumor activity of 9-aminocamptothecin (9-AC) in patients with recurrent platinum-"resistant" ovarian cancer; and to determine the nature and degree of toxicity of 9-AC in this cohort of patients.

METHODS

A multicenter phase II study was conducted by the Gynecologic Oncology Group (GOG). Patients were to receive 9-AC (colloidal dispersion) 25 microg/m(2)/h (600 microg/m(2)/day) IV over 120 h (5 days) beginning days 1 and 8. Dose adjustment was permitted for toxicity. This schedule was repeated every 21 days until disease progression or unacceptable adverse events. Hematopoietic growth factor support was used as necessary.

RESULTS

From January 1999 to December 2000, 29 member institutions of the GOG enrolled 58 patients. Two patients received no therapy; thus, 56 (97%) were evaluable. Median age was 61 (range: 33-81) years. A median of four (range: 1-32) courses of 9-AC was administered. The most frequent grade 3 or 4 toxicities were neutropenia in 46%, leukopenia in 37%, gastrointestinal in 29%, anemia in 25%, and thrombocytopenia in 21%. There was one possible treatment-related death. There were four (7%) complete and four (7%) partial responses, for an overall response rate of 14%. Eighteen (32%) patients had stable disease, 22 (39%) progressed, and response could not be assessed in 8 (14%).

CONCLUSION

The 9-AC at this dose and schedule showed limited activity comparable to that seen with other agents in platinum-resistant ovarian or primary peritoneal cancer.

Intraperitoneal cisplatin with intraperitoneal gemcitabine in patients with epithelial ovarian cancer: results of a phase I/II Trial

PURPOSE

The aims of this study were to determine the dose and schedule of i.p. cisplatin with i.p. gemcitabine in patients with persistent disease at second-look assessment, the toxicity of this regimen, and the time to treatment failure and overall survival.

EXPERIMENTAL DESIGN

We performed a Phase I/II evaluation of i.p. cisplatin at 75 mg/m(2) on day 1 with planned gemcitabine at 500, 750, 1000, or 1250 mg/m(2) i.p. on days 1, 8, and 15 on a 28-day schedule for four courses. Eligible patients completed surgical cytoreduction followed by adjuvant platinum-based chemotherapy. They had second-look assessment showing microscopic or macroscopic (< or =1 cm) disease, followed by i.p. port placement.

RESULTS

The Phase I dose-limiting toxicity was grade 3 thrombocytopenia at day 15 on dose level 1 (n = 5). The protocol was amended, and the Phase II portion accrued to 30 patients, who were given i.p. cisplatin (75 mg/m(2)) on day 1 and gemcitabine at 500 mg/m(2) on days 1 and 8 on a 21-day schedule for four courses. Nine patients were removed from the study: one each for hypersensitivity, cellulitis, and i.p. port malfunction; two for progression of disease; and four for renal toxicity. Other toxicities included grade 3 nausea (7%) and transient grade 3 neuropathy (3%). Grade 1 or 2 neuropathy was frequently seen (80%). Five patients (17%) returned to the operating room at a median of 6 months (range, 1-20 months) after i.p. therapy for evaluation of abdominal pain; two patients had recurrence, and all had areas of fibrous tissue with encasement of the bowel. In two patients, the fibrous tissue was causing partial bowel obstruction. No other patients had symptoms prompting surgical exploration. Pharmacokinetic (PK) studies showed a median area under the curve (AUC) i.p. of 3041 h. micro M (range, 676-5702 h. micro M) and AUC in plasma of 4.0 h. micro M (range, 0.92-8.2 h. micro M) reached between 120 and 240 min; the pharmacological advantage was 759-fold (range, 217-1415-fold) for i.p. versus plasma drug levels. The mean residence time of gemcitabine with i.p. administration was 4.7 h. The median time to progression of the intent to treat population was 15.93 months (95% confidence interval, 9.13-25.9 months), with a median overall survival of 43.5 months [95% confidence interval, (34.66- infinity)]. No statistical differences were seen with respect to overall survival if patients were grouped in terms of optimal debulking or not (median not reached versus 34.8 months, respectively; P = 0.16) or whether visible disease was present or not at the start of i.p. therapy (34.8 versus 47.7 months; P = 0.47). With regard to time to treatment failure, a statistical difference favored patients with optimal versus nonoptimal primary debulking (25.2 versus 10.2 months, respectively; P = 0.03).

CONCLUSIONS

The median time to treatment failure and overall survival of 15.9 months and 43.5 months, respectively, are consistent with our historical data in patients receiving i.p. platinum-based regimens for consolidation. The fibrotic changes seen in explored patients suggest local toxicity of this combination. The absolute benefit of i.p. consolidation requires randomized trials to assess efficacy.

Synthesis, benzodiazepine receptor binding, and anticonvulsant activity of 2,3-dihydro-3-oxo-5H-pyrido[3,4-b][1,4]benzothiazine-4-carbonitriles

A series of oxopyridobenzothiazines (azaphenothiazines) were prepared and evaluated for binding to the benzodiazepine receptor, anticonvulsant activity in the pentylenetetrazole-induced convulsion assay, and, in two cases, ability to increase punished responding in a standard conflict test. While parent compound 1a showed binding affinity comparable to chlorodiazepoxide (CDP), its potency in the anticonvulsant assay and the anticonflict test was considerably weaker than CDP. Of the variety of derivatives synthesized, only the 7-chloro compound 1b showed receptor affinity comparable to 1a with slightly improved in vivo activity. The poor correlation between receptor binding and in vivo activity may be due to variability in absorption or pharmacological responses unrelated to affinity for the benzodiazepine receptor.

Vehicle effects on activity of an anticonvulsant compound

The effect of several lipid and nonlipid pharmaceutical solvents on the in vivo activity of 1-diphenylmethyl-4- [(6 methyl-2-pyridyl) methyleneamino] piperazine (I) was evaluated in the mouse. The intensity of onset and the duration of anticonvulsant activity of the compound were affected depending on th type and form of liquid dosage preparation used. The rate of decline in anticonvulsant activity in the 80-20% response range followed apparent zero-order kinetics. A linear relationship between the observed ED50 and the concentration of sorbitol in the dosage form of I was observed. A reduction in the sorbitol content of the dosage form resulted in a proportional increase in the rapidity of onset and the duration of anticonvulsant activity of I. Emulsification restored both the onset and duration of pharmacological activity, which was virtually arrested when the compound was given orally as a solution in oil.