Dataset Information

A Phase I Trial of IGF-1R Inhibitor Cixutumumab and mTOR Inhibitor Temsirolimus in Metastatic Castration-resistant Prostate Cancer.

ABSTRACT:

Background

Despite frequent PTEN (phosphatase and tensin homologue) loss and Akt/mammalian target of rapamycin (mTOR) signaling in prostate cancer, the disease is insensitive to single-agent mTOR inhibition. Insulin-like growth factor-1 receptor inhibition might mitigate the feedback inhibition by Torc1 inhibitors, suppressing downstream Akt activation and, thus, potentiating the antitumor activity of mTOR inhibition.

Patients and methods

In the present phase I study, patients with metastatic castration-resistant prostate cancer received 6 mg/kg cixutumumab and 25 mg temsirolimus intravenously each week. The primary objective was safety and tolerability. Temsirolimus was decreased if ≥ 2 dose-limiting toxicities (DLTs) were observed in 6 patients. The correlative analyses included measurement of circulating tumor cells, [18F]-fluoro-2-deoxyglucose positron emission tomography, 16β-[18F]-fluoro-α-dihydrotestosterone positron emission tomography, and tumor biopsy.

Results

A total of 16 patients were enrolled across 3 cohorts (1, -1, -2). Two DLTs (grade 3 oral mucositis) were observed in cohort 1 (temsirolimus, 25 mg), and 1 DLT (grade 3 lipase) in cohort -1 (temsirolimus, 20 mg). The most common adverse events included hyperglycemia (100%; 31% grade 3), oral mucositis (63%; 19% grade 3), and diarrhea (44%; 0 grade 3). Low-grade pneumonitis occurred in 7 of 11 patients (44%; 0 grade 3), prompting the opening of a 3-weekly cohort (temsirolimus, 20 mg/kg), without pneumonitis events. No patient had a >50% decline in prostate-specific antigen from baseline. The best radiographic response was stable disease, with median study duration of 22 weeks (range, 7-63 weeks).

Conclusions

Despite a strong scientific rationale for the combination, temsirolimus plus cixutumumab demonstrated limited antitumor activity and a greater than expected incidence of toxicity, including low-grade pneumonitis and hyperglycemia. Hence, the trial was stopped in favor of alternative androgen receptor/phosphatidylinositol 3-kinase-directed combinatorial therapies.

SUBMITTER: McHugh DJ

PROVIDER: S-EPMC8394788 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Lessons learnedTemsirolimus maintenance therapy after docetaxel induction chemotherapyis safe in patients with castration-resistant prostate cancer, although biochemical or tumor responses are rare;does not diminish quality of life; anddelays radiological and/or symptomatic progression by approximately 6 months.BackgroundNo standard therapy is available for men with castration-resistant prostate cancer (CRPC) who have responded to docetaxel and do not yet have disease progression. Hence, we designed a single-arm phase II trial to explore whether the mTOR inhibitor temsirolimus can maintain the response to docetaxel without compromising quality of life.MethodsAfter successful docetaxel induction (75 mg/m(2) every 3 weeks; 6-10 cycles), 21 CRPC patients underwent temsirolimus maintenance treatment (25 mg weekly; 4 weeks per cycle). The primary endpoint was the time to treatment failure (TTTF) (i.e., radiological and/or symptomatic progression). The secondary endpoints included the tumor response rate (RECIST 1.0), safety (National Cancer Institute Common Terminology Criteria for Adverse Events, version 3.0), quality of life (Functional Assessment of Cancer Therapy-Prostate [FACT-P]), pain (Present Pain Intensity [PPI] scale), prostate-specific antigen (PSA) parameters, including time to PSA progression (TTPP) according to Prostate Cancer Clinical Trials Working Group criteria, and serial enumeration of circulating endothelial cells (CECs) and endothelial progenitor cells (CEPs).ResultsPatients received a median of 7 cycles of temsirolimus (range, 1-28), resulting in a median TTTF of 24.3 weeks (95% confidence interval [CI], 16.1-33.0), 1 partial tumor response (4.8%), 1 PSA response (4.8%), and a median TTPP of 12.2 weeks (95% CI, 7.8-23.9). Grade 3-4 adverse events were infrequent, and FACT-P and PPI scores remained stable during treatment. CECs did not predict clinical benefit, and CEPs were not consistently detectable.ConclusionTemsirolimus maintenance therapy after successful docetaxel induction is feasible, does not adversely affect quality of life, and, in this exploratory single-arm phase II study, resulted in a median TTTF of 24.3 weeks.