Low-dose pembrolizumab re-treatment induced complete radiologic and molecular remission in Hodgkin lymphoma recurring from a previous relapse successfully treated by pembrolizumab

What is the best salvage therapy for Hodgkin lymphoma?

PURPOSE OF REVIEW

Historically, salvage chemotherapy followed by high-dose chemotherapy and autologous stem cell transplant (HDT/ASCT) was the mainstay approach for relapsed or refractory classic HL. The emergence of novel agents for HL, such as brentuximab vedotin and programmed death-1 (PD-1) blockade has revolutionized therapeutic strategies, yielding excellent results. This review aims to provide a comprehensive overview of new salvage therapies and offer insights into forthcoming therapeutic options.

RECENT FINDINGS

The incorporation of brentuximab vedotin and PD-1 blockade into salvage therapy before HDT/ASCT has led to markedly improved outcomes. Notably, PD-1 based salvage studies yield posttransplant 2-year progression-free survival rates approaching 90%, marking a significant advancement in the treatment of Hodgkin lymphoma (HL). Studies are beginning to explore nontransplant treatment approaches following front-line treatment failure and may identify certain risk groups eligible for these strategies.

SUMMARY

The landscape of HL treatment is rapidly evolving, leading to significant changes in the standard of care. Novel agents are now administered earlier in the disease course, resulting in higher cure rates. The focus of treatment is shifting towards achieving cure with minimal toxicity, reducing exposure to various agents, and advancing research in optimizing treatment sequencing and patient selection for less intensive therapies.

Dosing Regimens of Immune Checkpoint Inhibitors: Attempts at Lower Dose, Less Frequency, Shorter Course

Immune checkpoint inhibitors (ICIs) are a revolutionary breakthrough in the field of cancer by modulating patient's own immune system to exert anti-tumor effects. The clinical application of ICIs is still in its infancy, and their dosing regimens need to be continuously adjusted. Pharmacokinetic/pharmacodynamic studies showed a significant plateau in the exposure-response curve, with high receptor occupancy and plasma concentrations achieved at low dose levels. Coupled with concerns about drug toxicity and heavy economic costs, there has been an ongoing quest to reevaluate the current ICI dosing regimens while preserving maximum clinical efficacy. Many clinical data showed remarkable anticancer effects with ICIs at the doses far below the approved regimens, indicating the possibility of dose reduction. Our review attempts to summarize the clinical evidence for ICIs regimens with lower-dose, less-frequency, shorter-course, and provide clues for further ICIs regimen optimization.

Pharmacokinetic Simulation Analysis of Less Frequent Nivolumab and Pembrolizumab Dosing: Pharmacoeconomic Rationale for Dose Deescalation

Nivolumab and pembrolizumab, anti-programmed cell death protein 1 monoclonal antibodies, have revolutionized oncology but are expensive. Using an interventional pharmacoeconomic approach, these drugs can be administered less often to reduce costs and increase patient convenience while maintaining efficacy. Both drugs are good candidates for less frequent dosing because of long half-lives and no evidence of a relationship of dose to efficacy. Established population pharmacokinetic models for both nivolumab and pembrolizumab were used to simulate profiles for multiple dosing regimens on 1000 randomly generated virtual patients. Simulations were initially performed on standard dose regimens to validate these in silico predictions. Next, simulations of nivolumab 0.3 mg/kg every 3 weeks revealed that >95% of patients maintained ≥1.5 μg/mL at steady state, which was inferred as the minimum effective concentration (MEC) for both drugs. Various alternative dosing regimens were simulated for both drugs to determine which regimen(s) can maintain this MEC in >95% of patients. Extended dosing regimens of nivolumab 240 mg every 4 weeks and 480 mg every 8 weeks along with pembrolizumab 200 mg every 6 weeks were simulated, showing that >95% of patients maintained MEC or greater. These simulations demonstrate the potential to reduce drug exposure by at least 50%, thus substantially reducing patient visits (as well as costs), while maintaining equivalent efficacy. These models provide the scientific justification for an ongoing prospective randomized clinical trial comparing standard interval fixed dosing with extended interval fixed dosing, and ultimately an efficacy-driven comparative trial.

The Right Dose: From Phase I to Clinical Practice

To realize the full potential of promising new anticancer drugs, it is of paramount importance to administer them at the right dose. The aim of this educational article is to provide several opportunities to optimize anticancer drug dosing, focusing on oral targeted therapies. First, therapeutic drug monitoring can optimize exposure in individual patients, if the optimal concentration is known. This approach is of particular interest in regard to oral kinase inhibitors with high interindividual pharmacokinetic variability. If exposure is related to response, then therapeutic drug monitoring is potentially feasible, although the clinical utility of this approach has not yet been established. Other approaches to reduce variability include administration of more frequent, smaller doses and administration under optimal prandial conditions. However, for many drugs, the labeled dose has not been demonstrated to be the optimal dose; for such agents, the vast majority of patients may be receiving excessive doses, which results in excessive toxicity. Furthermore, administration of lower off-label doses may reduce both medical and financial toxicity. These strategies should be applied from registration studies to clinical practice, with the goal of better optimizing anticancer treatment.

Low-dose pembrolizumab and nivolumab were efficacious and safe in relapsed and refractory classical Hodgkin lymphoma: Experience in a resource-constrained setting

The efficacy and safety of low-dose anti-PD1 antibodies in relapsed/refractory classical Hodgkin lymphoma (cHL) require confirmation. Pembrolizumab (100 mg every 3 weeks, Q3W) or nivolumab (40 mg Q2W) were administered to patients with relapsed/refractory cHL. In the pembrolizumab cohort (N = 11), who had failed a median of three (1-6) therapies (brentuximab vedotin [BV]: 91%; autologous hematopoietic stem cell transplantation [auto-HSCT]: 18%), the overall response rate (ORR) by positron emission tomography-computed tomography was 100% (metabolic complete response [mCR]: 73%; partial response [PR]: 27%). Median cumulative dose for achieving best response was 400 (300-800) mg. Median progression-free survival (PFS) was 35 months. Median overall survival (OS) was not reached. Adverse events (AEs) of grade 1-2 were observed in three patients. In the nivolumab cohort (N = 6), who had failed a median of three (2-6) therapies (BV: 50%; auto-HSCT: 17%; allogeneic HSCT: 34%), the ORR was 100% (mCR: 67%; PR: 17%; indeterminate response: 17%). Median cumulative dose for achieving best response was 160 (160-360) mg. Median PFS was 33 months. Median OS was not reached. AEs of grade 1-2 were observed in four patients, two of whom had pre-existing autoimmune conditions. Five patients with Epstein-Barr virus (EBV) positive Reed-Sternberg cells underwent monitoring of plasma EBV DNA, which became negative in four mCR patients but remained positive in one PR patient who died ultimately from refractory lymphoma. Low-dose pembrolizumab and nivolumab were highly efficacious and safe in relapsed/refractory cHL. These observations have significant financial implications in resource-constrained settings.