Early biochemical and radiographic response after one cycle of [177Lu]Lu-PSMA I&T radioligand therapy in metastatic castration-resistant prostate cancer patients

PURPOSE

The aim of this study was to investigate very early radiographic PSMA PET response after one cycle of [177Lu]Lu-PSMA I&T radioligand therapy (RLT) of metastatic castration-resistant prostate cancer (mCRPC) and to assess its role in predicting overall response and survival.

METHODS

This retrospective study enrolled 40 mCRPC patients who were treated with a median of 3 (2-9) [177Lu]Lu-PSMA I&T RLT cycles. Biochemical response was based on the relative change of serum PSA according to PCWG3 criteria, while radiographic response referred to the relative change of PSMA-derived total viable tumor volumes expressed as total lesion PSMA (TLP).

RESULTS

After one cycle of RLT, biochemical partial response (PR) was seen in 8/40 (20.0%), stable disease (SD) in 22/40 (55.0%), and progressive disease (PD) in 10/40 (25%) patients. In PSMA PET, very early molecular PR was observed in 12 (30.0%), SD in 19 (47.5%), and PD in 9 (22.5%) subjects. The PSA and TLP nadir were achieved after a median of 1 (1-5) and 2 (1-6) cycles, respectively. Nineteen (47.5%) patients showed overall biochemical PR, 11 (27.5%) had SD, and 10 (25%) experienced PD. In PSMA-directed PET, 4 patients experienced molecular complete response (CR), 24 (60.0%) had PR, 4 (10.0%) SD, and 8 (20.0%) PD. Early biochemical or radiographic response was not associated with longer overall survival (OS). Overall biochemical responders had a nearly significantly longer median OS (22.7 months) than non-responders (14.4 months, p = 0.08). Early PSA progression was associated with shorter OS (12.2 months), compared to biochemical SD/PR (18.7 months, p = 0.09).

CONCLUSION

In this retrospective cohort, there was no association between early PSMA PET radiographic response and overall survival; hence, treatment should not be prematurely discontinued. In contrast, early PSA progression after one cycle of [177Lu]Lu-PSMA I&T RLT was an indicator of overall progression and poor clinical outcome.

Any decline in prostate-specific antigen levels identifies survivors scheduled for prostate-specific membrane antigen-directed radioligand therapy

BACKGROUND

Prostate-specific membrane antigen (PSMA)-targeted radioligand therapy (RLT) is increasingly incorporated in the therapeutic algorithm of patients with metastatic castration-resistant prostate cancer (mCRPC). We aimed to elucidate the predictive performance of early biochemical response for overall survival (OS).

MATERIALS AND METHODS

In this bicentric analysis, we included 184 mCRPC patients treated with ¹⁷⁷ Lu-PSMA RLT. Response to treatment was defined as decrease in prostate-specific antigen (PSA) levels 8 weeks after the first cycle of RLT (any decline or >50% according to Prostate Cancer Working Group 3). OS of responders and nonresponders was then compared using Kaplan-Meier curves and log-rank comparison.

RESULTS

A total of 114/184 patients (62.0%) showed any PSA decline (PSA response >50%, 55/184 [29.9%]). For individuals exhibiting a PSA decline >50%, OS of 19 months was significantly longer relative to nonresponders (13 months; hazard ratio of death [HR] = 0.64, 95% confidence interval [95% CI] = 0.44-0.93; p = 0.02). However, the difference was even more pronounced for any PSA decline, with an OS of 19 months in responders, but only 8 months in nonresponders (HR = 0.39, 95% CI = 0.25-0.60; p < 0.001).

CONCLUSIONS

In mCRPC patients scheduled for RLT, early biochemical response was tightly linked to prolonged survival, irrespective of the magnitude of PSA decline. As such, even in patients with PSA decrease of less than 50%, RLT should be continued.

mCRPC patients with PSA fluctuations under radioligand therapy have comparable survival benefits relative to patients with sustained PSA decrease

Introduction

In men with metastatic castration-resistant prostate cancer (mCRPC) scheduled for prostate-specific membrane antigen (PSMA)-targeted radioligand therapy (RLT), biochemical response is assessed based on repeated measurements of prostate-specific antigen (PSA) levels. We aimed to determine overall survival (OS) in patients experiencing sustained PSA increase, decrease, or fluctuations during therapy.

Materials and methods

In this bicentric study, we included 176 mCRPC patients treated with PSMA-directed RLT. PSA levels were determined using blood samples prior to the first RLT and on the admission days for the following cycles. We calculated relative changes in PSA levels compared to baseline. Kaplan–Meier curves as well as log-rank test were used to compare OS of different subgroups, including patients with sustained PSA increase, decrease, or fluctuations (defined as change after initial decrease or increase after the first cycle).

Results

Sixty-one out of one hundred seventy-six (34.7%) patients showed a sustained increase and 86/176 (48.8%) a sustained decrease in PSA levels. PSA fluctuations were observed in the remaining 29/176 (16.5%). In this subgroup, 22/29 experienced initial PSA decrease followed by an increase (7/29, initial increase followed by a decrease). Median OS of patients with sustained decrease in PSA levels was significantly longer when compared to patients with sustained increase of PSA levels (19 vs. 8 months; HR 0.35, 95% CI 0.22–0.56; P < 0.001). Patients with PSA fluctuations showed a significantly longer median OS compared to patients with sustained increase of PSA levels (18 vs. 8 months; HR 0.49, 95% CI 0.30–0.80; P < 0.01), but no significant difference relative to men with sustained PSA decrease (18 vs. 19 months; HR 1.4, 95% CI 0.78–2.49; P = 0.20). In addition, in men experiencing PSA fluctuations, median OS did not differ significantly between patients with initial decrease or initial increase of tumor marker levels (16 vs. 18 months; HR 1.2, 95% CI 0.38–4.05; P = 0.68).

Conclusion

Initial increase or decrease of PSA levels is sustained in the majority of patients undergoing RLT. Sustained PSA decrease was linked to prolonged survival and men with PSA fluctuations under treatment experienced comparable survival benefits. As such, transient tumor marker oscillations under RLT should rather not lead to treatment discontinuation, especially in the absence of radiological progression.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00259-022-05910-w.

Baseline clinical characteristics predict overall survival in patients undergoing radioligand therapy with [177Lu]Lu-PSMA I&T during long-term follow-up

Background

Radioligand therapy (RLT) with ¹⁷⁷Lu-labeled prostate-specific membrane antigen (PSMA) ligands is associated with prolonged overall survival (OS) in patients with advanced, metastatic castration-resistant prostate cancer (mCRPC). A substantial number of patients, however, are prone to treatment failure. We aimed to determine clinical baseline characteristics to predict OS in patients receiving [¹⁷⁷Lu]Lu-PSMA I&T RLT in a long-term follow-up.

Materials and methods

Ninety-two mCRPC patients treated with [¹⁷⁷Lu]Lu-PSMA I&T with a follow-up of at least 18 months were retrospectively identified. Multivariable Cox regression analyses were performed for various baseline characteristics, including laboratory values, Gleason score, age, prior therapies, and time interval between initial diagnosis and first treatment cycle (interval_{Diagnosis-RLT}, per 12 months). Cutoff values for significant predictors were determined using receiver operating characteristic (ROC) analysis. ROC-derived thresholds were then applied to Kaplan–Meier analyses.

Results

Baseline C-reactive protein (CRP; hazard ratio [HR], 1.10, 95% CI 1.02–1.18; P = 0.01), lactate dehydrogenase (LDH; HR, 1.07, 95% CI 1.01–1.11; P = 0.01), aspartate aminotransferase (AST; HR, 1.16, 95% CI 1.06–1.26; P = 0.001), and interval_{Diagnosis-RLT} (HR, 0.95, 95% CI 0.91–0.99; P = 0.02) were identified as independent prognostic factors for OS. The following respective ROC-based thresholds were determined: CRP, 0.98 mg/dl (area under the curve [AUC], 0.80); LDH, 276.5 U/l (AUC, 0.83); AST, 26.95 U/l (AUC, 0.73); and interval_{Diagnosis-RLT}, 43.5 months (AUC, 0.68; P < 0.01, respectively). Respective Kaplan–Meier analyses demonstrated a significantly longer median OS of patients with lower CRP, lower LDH, and lower AST, as well as prolonged interval_{Diagnosis-RLT} (P ≤ 0.01, respectively).

Conclusion

In mCRPC patients treated with [¹⁷⁷Lu]Lu-PSMA I&T, baseline CRP, LDH, AST, and time interval until RLT initiation (thereby reflecting a possible indicator for tumor aggressiveness) are independently associated with survival. Our findings are in line with previous findings on [¹⁷⁷Lu]Lu-PSMA-617, and we believe that these clinical baseline characteristics may support the nuclear medicine specialist to identify long-term survivors.

Matched-pair analysis of [177Lu]Lu-PSMA I&T and [177Lu]Lu-PSMA-617 in patients with metastatic castration-resistant prostate cancer

Background

Labelled with lutetium-177, the urea-based small molecules PSMA I&T and PSMA-617 are the two agents most frequently used for radioligand therapy (RLT) in patients with advanced metastatic castration-resistant and prostate-specific membrane antigen (PSMA) expressing prostate cancer (mCRPC). In this matched-pair analysis, we aimed to compare the toxicity and efficacy of both agents for PSMA-directed RLT.

Materials and methods

A total of 110 mCRPC patients from two centres were accrued, 55 individuals treated with [¹⁷⁷Lu]Lu-PSMA I&T, and a matched cohort of 55 patients treated with [¹⁷⁷Lu]Lu-PSMA-617. Matching criteria included age at the first cycle, Gleason score, prostate-specific antigen (PSA) values, and previous taxane-based chemotherapy. Using common terminology criteria for adverse events (CTCAE v. 5.0), toxicity profiles were investigated (including bone marrow and renal toxicity). Overall survival (OS) between both groups was compared.

Results

Toxicity assessment revealed grade III anaemia in a single patient (1.8%) for [¹⁷⁷Lu]Lu-PSMA I&T and five (9.1%) for [¹⁷⁷Lu]Lu-PSMA-617. In addition, one (1.9%) grade III thrombopenia for [¹⁷⁷Lu]Lu-PSMA-617 was recorded. Apart from that, no other grade III/IV toxicities were present. A median OS of 12 months for patients treated with [¹⁷⁷Lu]Lu-PSMA I&T did not differ significantly when compared to patients treated with [¹⁷⁷Lu]Lu-PSMA-617 (median OS, 13 months; P = 0.89).

Conclusion

In this matched-pair analysis of patients receiving one of the two agents most frequently applied for PSMA RLT, the rate of clinically relevant toxicities was low for both compounds. In addition, no relevant differences for OS were observed.

Hematotoxicity and Nephrotoxicity in Prostate Cancer Patients Undergoing Radioligand Therapy with [177Lu]Lu-PSMA I&T

Simple Summary

Radioligand therapy (RLT) with prostate-specific membrane antigen (PSMA)-directed agents has shown remarkable results in patients with advanced prostate cancer. Our objective was to provide data on the side effect profile of PSMA-directed RLT using the therapeutic radiotracer [¹⁷⁷Lu]Lu-PSMA I&T. We evaluated patients with castration-resistant metastatic prostate cancer treated with at least three cycles of [¹⁷⁷Lu]Lu-PSMA I&T. A substantial fraction of the patients already had impaired renal function and/or reduced white blood cell counts at baseline, but the degree of nephrotoxicity or hematotoxicity under RLT was low. No severe toxicities occurred under RLT.

Abstract

(1) Background: Prostate-specific membrane antigen (PSMA)-directed radioligand therapy (RLT) has shown remarkable results in patients with advanced prostate cancer. We aimed to evaluate the toxicity profile of the PSMA ligand [¹⁷⁷Lu]Lu-PSMA I&T. (2) Methods: 49 patients with metastatic, castration-resistant prostate cancer treated with at least three cycles of [¹⁷⁷Lu]Lu-PSMA I&T were evaluated. Prior to and after RLT, we compared leukocytes, hemoglobin, platelet counts, and renal functional parameters (creatinine, eGFR, n = 49; [^99mTc]-MAG3-derived tubular extraction rate (TER), n = 42). Adverse events were classified according to the Common Terminology Criteria for Adverse Events (CTCAE) v5.0 and KDIGO Society. To identify predictive factors, we used Spearman’s rank correlation coefficient. (3) Results: A substantial fraction of the patients already showed impaired renal function and reduced leukocyte counts at baseline. Under RLT, 11/49 (22%) patients presented with nephrotoxicity CTCAE I or II according to creatinine, but 33/49 (67%) according to eGFR. Only 5/42 (13%) showed reduced TER, defined as <70% of the age-adjusted mean normal values. Of all renal functional parameters, absolute changes of only 2% were recorded. CTCAE-based re-categorization was infrequent, with creatinine worsening from I to II in 2/49 (4.1%; GFR, 1/49 (2%)). Similar results were recorded for KDIGO (G2 to G3a, 1/49 (2%); G3a to G3b, 2/49 (4.1%)). After three cycles, follow-up eGFR correlated negatively with age (r = −0.40, p = 0.005) and the eGFR change with Gleason score (r = −0.35, p < 0.05) at baseline. Leukocytopenia CTCAE II occurred only in 1/49 (2%) (CTCAE I, 20/49 (41%)) and CTCAE I thrombocytopenia in 7/49 (14%), with an absolute decrease of 15.2% and 16.6% for leukocyte and platelet counts. Anemia CTCAE II occurred in 10/49 (20%) (CTCAE I, 36/49 (73%)) with a decrease in hemoglobin of 4.7%. (4) Conclusions: After PSMA-targeted therapy using [¹⁷⁷Lu]Lu-PSMA I&T, no severe (CTCAE III/IV) toxicities occurred, thereby demonstrating that serious adverse renal or hematological events are unlikely to be a frequent phenomenon with this agent.

Intrathecal baclofen in tetanus: four cases and a review of reported cases

OBJECTIVE

Spasms in patients with generalized tetanus can be suppressed by a spinal intrathecal infusion of baclofen. We report on four patients and review reported cases treated by this method elsewhere.

DESIGN

Intrathecal baclofen infusion was started with a bolus dose (300-500 micrograms) and continued at a steady rate of 500-1000 micrograms/day. The dose was increased in daily steps as needed.

RESULTS

Doses of baclofen of 500, 1000, or 2000 micrograms/day were effective in three patients, while 1500 micrograms/day was insufficient in the fourth. Bradycardia and hypotonia occurred in one patient at a dose of 2000 micrograms/day but resolved after the dose was reduced to 1500 micrograms/day. Another patient developed hypotonia when a bolus of 500 micrograms was given after a steady infusion of 1500 micrograms/day. Voluntary movements were preserved in one and returned in two patients when sedation, induced by initial diazepam infusions, receded. The fourth patient needed diazepam during most of the treatment with intrathecal baclofen and required mechanical ventilation while being treated with baclofen.

CONCLUSIONS

A catheter position higher than T11 would possibly have yielded better results. It may be necessary to adapt the dose during the course of the illness. The preservation of respiratory drive and voluntary movements is the main advantage of treating tetanus with intrathecal baclofen. Additionally it helps to reduce sympathetic hyperactivity. Mortality may thereby be reduced.

The value of spinal magnetic resonance imaging (MRI) in locating prolapses of lumbar intervertebral discs

Between 1986 and 1988 100 patients in whom MRI had been used to diagnose prolapses of lumbar intervertebral discs were admitted to the neurosurgical department of the Munich Technical University. MRI proved to be a valuable diagnostic technique, even if one has to concede certain limitations to the usefulness of the results when compared to conventional methods, particularly in such cases where clinical symptoms are not clear. Typical findings are illustrated and compared with those seen in MRI, whose relative importance is discussed.

[Perioperative cytostatic treatment of malignant supratentorial brain tumors with BCNU with special reference to tumor site]

During the period from 1979 until 1986, sixty male and female patients were treated perioperatively in the Neurosurgical Department of the Surgical Clinic and OPD of the Munich Technical University with the alkylating agent BCNU. Up to five treatment cycles were employed, the first treatment cycle being initiated pre-operatively. In none of the cases were disorders of wound healing seen. Among these sixty patients there was one case of suspected BCNU lung and one case of massive leukopenia. Considering the rate of complications described in the international literature, this figure is extremely small. As to the study of the mean survival time, only 30 patients presenting supratentorial malignant tumours of comparable localisation were included. In light of these strict criteria the perioperative BCNU treatment at our clinic resulted in a mean survival time of 67.1 weeks which in comparison with the literature can be regarded as a good result. We would therefore only recommend cytostatic treatment with peroperative administration of BCNU.