Final analysis of phase II results with cemiplimab in metastatic basal cell carcinoma after hedgehog pathway inhibitors

BACKGROUND

Metastatic basal cell carcinoma (mBCC) is a rare condition with no effective second-line treatment options. Cemiplimab is an immune checkpoint inhibitor that blocks the binding of programmed cell death-1 (PD-1) to its ligands, programmed death-ligand 1 (PD-L1) and programmed death-ligand 2 (PD-L2). Here, we present the final analysis of cemiplimab in patients with mBCC after first-line hedgehog pathway inhibitor (HHI) treatment (NCT03132636).

PATIENTS AND METHODS

In this open-label, single-arm, phase II study, adults with mBCC and Eastern Cooperative Oncology Group performance status ≤1, post-HHI treatment, received cemiplimab 350 mg intravenously every 3 weeks for ≤93 weeks or until disease progression or unacceptable toxicity. The primary endpoint was objective response rate (ORR) by independent central review (ICR). Duration of response (DOR) was a key secondary endpoint. Other secondary endpoints were ORR per investigator assessment, progression-free survival (PFS), overall survival (OS), complete response rate, safety, and tolerability.

RESULTS

Fifty-four patients were enrolled: 70% were male and the median age of patients was 64 [interquartile range (IQR) 57.0-73.0] years. The median duration of follow-up was 8 months (IQR 4-21 months). The ORR per ICR was 22% [95% confidence interval (CI) 12% to 36%], with 2 complete responses and 10 partial responses. Among responders, the median time to response per ICR was 3 months (IQR 2-7 months). The estimated median DOR per ICR was not reached [95% CI 10 months-not evaluable (NE)]. The disease control rate was 63% (95% CI 49% to 76%) per ICR and 70% (95% CI 56% to 82%) per investigator assessment. The median PFS per ICR was 10 months (95% CI 4-16 months); the median OS was 50 months (95% CI 28 months-NE). The most common treatment-emergent adverse events were fatigue [23 (43%)] and diarrhoea [20 (37%)]. There were no treatment-related deaths.

CONCLUSIONS

Cemiplimab demonstrated clinically meaningful antitumour activity, including durable responses, and an acceptable safety profile in patients with mBCC who had disease progression on or intolerance to HHI therapy.

Initial phase II experience of ipilimumab (IPI) alone and in combination with radiotherapy (XRT) in patients with metastatic castration-resistant prostate cancer (mCRPC)

5138

Background: IPI is a fully human, monoclonal anti-CTLA-4 antibody capable of enhancing anti-tumor immunity. In preclinical models, XRT releases tumor antigens and enhances anti-tumor activity of CTLA-4 blockade. In the dose escalation part of this Phase I/II trial 10 mg/kg dosing of IPI with or without prior priming by single fraction XRT was feasible. We now report initial phase II results. Methods: 45 patients (pts) with mCRPC and ECOG PS of 0–1 received 10 mg/kg q3 weeks (wks) X 4 of IPI in 3 groups: (1) IPI alone n=16, (2) IPI + XRT n=15 chemotherapy naïve (NoCHEMO), and (3) IPI + XRT n=14 chemotherapy experienced (CHEMO) pts. XRT (800 cGy) was given to up to 3 involved bony sites (GI tract sparing) just prior to starting IPI. PSA was monitored monthly, with scans q 3 months. Endpoints were to confirm safety and an initial assessment of activity. Results: 17 pts (38%) experienced 26 immune-related adverse events (irAEs) including diarrhea/colitis (12), rash/pruritus (6), hepatitis (4), endocrinopathy (4). 11 pts (24%) experienced 13 ≥ Grade 3 irAEs: GI (9; 20%) and hepatitis (4; 9%); all resolved with immunosuppression. 10 of 45 pts (22%; 95% CI 10–34%) had confirmed PSA declines ≥ 50% as follows in the table below. Median time to PSA decline was 5.7 wks (r 3 to 21 wks); median duration 23 wks (r 3 to 84+ wks). In one pt dosed with IPI alone, PSA ≤ 0.05 ng/ml, as well as a CR of bone, nodal and prostate lesions continue for 54+ and 84+ wks, respectively. Conclusions: irAEs in the 10 mg/kg cohorts are similar in type and rate to IPI in melanoma. irAEs and PSA declines occurred in chemotherapy naïve and post chemotherapy patients, and with or without XRT. Addition of XRT to 10 mg/kg is well tolerated. Time to response can be delayed, with a durable median response of 23 wks. Further study of IPI in mCRPC is warranted, with or without XRT as a potential immunosupportive maneuver to augment clinical responses to IPI.

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Phase II experience with MDX-1106 (Ono-4538), an anti-PD-1 monoclonal antibody, in patients with selected refractory or relapsed malignancies

3018

Background: Programmed death-1 (PD-1), an inhibitory receptor expressed on activated T cells, may suppress antitumor immunity. This expansion cohort in a phase I/II trial of MDX-1106, a fully human IgG4 antibody blocking PD-1, sought to further evaluate the safety and activity of the 10 mg/kg dose. Other objectives included evaluation of pharmacokinetics (PK) and immunological effects. Methods: Patients (pts) with treatment refractory metastatic non-small cell lung cancer (NSCLC), renal cell carcinoma (RCC), colon cancer (CC), melanoma (MEL), or prostate cancer (CRPC), and no history of autoimmune disease received a single infusion of MDX-1106 at 10 mg/kg. Disease status was evaluated at week (wk) 8 by RECIST criteria. Pts with stable disease or lesional responses could receive additional MDX-1106 at wks 12 and 16. Those with PR/CR were observed without retreatment. Results: 21 pts (5 CC, 2 NSCLC, 8 MEL, 5 HRPC, 1 RCC) were treated from 10/07 to present, and 6 were retreated. No MDX-1106 related SAEs occurred. One pt developed arthritic symptoms requiring treatment, and 2 pts had asymptomatic TSH elevation. One pt with RCC had a PR after 3 doses, lasting 5+ months (mo). Lesional regressions (“mixed response”) were seen in 2 MEL pts; to date, one has received 7 doses of MDX-1106 over 15 mo without serious toxicity. Biopsy of a regressing MEL lymph node metastasis showed a moderately increased and selective CD8+ T cell infiltrate post treatment. The median serum t 1/2 of MDX-1106 was 20.6 days, which was roughly 50% longer than observed for lower doses. There was no evidence of immunogenicity based on HAHA development. Interestingly, in contrast to PK results, flow cytometric analysis demonstrated sustained occupancy of 60–80% PD-1 molecules on T cells for at least 3 mo following a single dose. Analyses of circulating lymphocyte subsets and tumor B7-H1 expression are in progress. Conclusions: Intermittent dosing of MDX-1106 at 10 mg/kg demonstrated clinical activity against RCC and MEL without serious toxicity. Therapy with MDX-1106 to enhance endogenous antitumor immunity, either alone or combined with other immunological therapies, warrants further study.

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Biochemical and immunologic correlates of clinical response in a combination trial of the GM-CSF-gene transduced allogeneic prostate cancer immunotherapy and ipilimumab in patients with metastatic hormone-refractory prostate cancer (mHRPC)

5120

Background: A Phase 1 trial is underway to study the GM-CSF-secreting immunotherapy for prostate cancer (GVAX immunotherapy [GVAX IT]) and ipilimumab (ipi) in mHRPC patients (pts). Methods: Twelve pts were treated for 24 weeks (wks) with bi-weekly intradermal injections of GVAX IT and monthly Ipi. Pts were enrolled in cohorts of 3; each cohort received an escalating dose of ipi: 0.3, 1, 3 or 5 mg/kg. Results: Median follow-up is 15.0 months. All pts had GVAX IT injection site reactions. Five of six pts at the higher ipi doses (3 and 5 mg/kg) developed Grade 2 or 3 immune-related endocrinopathy, consistent with hypophysitis manifested by adrenal insufficiency and/or hypothyroidism, all successfully treated with standard hormone replacement. Two pts were tapered off Synthroid within 6 months (m). There was no induction of the alpha-21-hydroxylase auto-antibody that is seen in 90% of cases of auto-immune adrenal insufficiency. One pt in the 5 mg group developed a Grade 3 dose-limiting alveolitis. PSA responses (declines > 50%) were seen in 5/6 treated at the two higher ipi doses with median response duration of 4.9 m (2 on-going at 7.2 m and 12.8 m). These PSA responses were associated with immune-related endocrinopathy but were not consistently correlated with declines in adrenal androgens. One pt had resolution of measurable disease on abdominal CT scan. Immunomonitoring studies showed T cell and dendritic cell activation, more pronounced at higher doses. Biopsies of injection sites showed T cell infiltration. Multiple tumor-reactive antibodies (abs) induced by tx were identified by serologic analysis (SEREX), including abs to filamin B. Screening against 20 defined prostate cancer antigens demonstrated induction of abs to PSMA and NY-ESO-1. Conclusions: The GVAX IT and ipilimumab combination is active in mHRPC. There was an association between PSA response and immune-related adverse events. The PSA responses cannot be accounted for by adrenal insufficiency. The relationship between clinical activity and serologic response to identified antigens is under investigation. Tx of 16 additional pts is planned.

No significant financial relationships to disclose.