Cellular immunocompetence in melanoma: effect of extent of disease and immunotherapy

[Progress on Neoadjuvant Immunotherapy for Resectable Non-small Cell Lung Cancer]

In recent years, there has been a consensus regarding the enhancement of prognosis in patients with advanced non-small cell lung cancer (NSCLC) through the utilization of immune checkpoint inhibitors (ICIs). Numerous clinical studies have also demonstrated the substantial value of immunotherapy for resectable NSCLC patients. Nevertheless, there remain controversies surrounding the exploration of immune combination strategies, treatment-related side effects, prognostic biomarkers, as well as other issues in the neoadjuvant therapy setting. Consequently, this article presents a comprehensive overview of the recent advancements in neoadjuvant immunotherapy for resectable NSCLC, stimulating fresh perspectives and delving into its merits and challenges in clinical application.
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Neoadjuvant immune checkpoint inhibitor therapy in resectable non-small cell lung cancer

Only a minority of lung cancers are resectable at diagnosis, and many of these will eventually relapse. Adjuvant chemotherapy in this setting has a modest survival advantage, and there is significant need for new approaches to improve cure rates. Checkpoint inhibitor immunotherapy has transformed the prognosis for advanced lung cancer, and is increasingly being used in the neoadjuvant setting alone, or in combination with cytotoxic chemotherapy. While this has demonstrated convincing improvements in event-free survival and pathologic response, questions remain over optimal duration of therapy, predictive and prognostic biomarkers, response assessment and combination with other modalities. In addition, these results must be considered in the context of recent positive studies of adjuvant immunotherapy. Here, we summarise preclinical context and clinical trials in this space, discuss areas of controversy and pitfalls, and consider future challenges.

Neoadjuvant immune checkpoint inhibitors in high-risk stage III melanoma

The success of immunotherapy and targeted therapy for metastatic melanoma has generated considerable interest in the adjuvant setting, even though high-risk stage III melanoma (with or without in-transit metastases) still holds a substantial probability of relapse, despite surgical resection and available adjuvant treatments. Based on preclinical and clinical trials in resectable melanoma, immune checkpoint inhibitors can enhance anti-tumor immunity by activating antigen-specific T cells found in the primary site. These tumor-reactive T cells continue to exert their anti-tumor effects on remaining neoplastic cells after resection of the primary tumor, potentially preventing relapses from reoccurring. Several trials in the neoadjuvant setting have been conducted for melanoma patients using checkpoint inhibitors with promising early data, showing an improvement of operability and clinical outcomes. Hence, in this study, we review and discuss the available published and ongoing clinical trials to explore the scientific background behind immunotherapy in the neoadjuvant context.

Neoadjuvant immunotherapy for non-small cell lung cancer: right drugs, right patient, right time?

Standard curative treatment of early-stage non-small cell lung cancer (NSCLC) involves surgery in combination with postoperative (adjuvant) platinum-based chemotherapy where indicated. Preoperative (neoadjuvant) therapies offer certain theoretical benefits compared with adjuvant approaches, including the ability to assess on-treatment response, reduce the tumor bulk prior to surgery, and enhance tolerability in the preoperative setting. Indeed, the use of neoadjuvant therapies are well established in other cancers such as breast and rectal cancers to debulk the tumor and guide ongoing therapy, and neoadjuvant chemotherapy has similar efficacy but less toxicity in NSCLC. More recently, immune checkpoint inhibitors (ICI) targeting programmed death-1 (PD1)/PD1-ligand 1 (PD-L1) have transformed the treatment of advanced NSCLC; the unique mechanisms of action of ICI offer additional rationale for assessment in the neoadjuvant setting. Preclinical studies in mouse cancer models support the proof of concept of neoadjuvant ICI (NAICI) through improvement of T-cell effector function and long-term memory induction. Preliminary early-phase human trial data support the proposition that NAICI in NSCLC may provide an feasible and potentially efficacious future treatment strategy and large, randomized phase III trials are currently recruiting to assess this approach. However, outstanding issues include defining optimal treatment combinations which balance high efficacy with acceptable toxicity, validating biomarkers to aid in patient selection, and avoiding potential pitfalls such as missing a window for successful surgery, that is, choosing the right drugs, for the right patient, at the right time. Predictive biomarkers to direct selection of therapy are required, and the validation of major pathological response (MPR) as a surrogate for survival will be important in the uptake of the neoadjuvant approach.

Rationalizing the pathway to personalized neoadjuvant immunotherapy: the Lombard Street Approach

Neoadjuvant chemo(radio)therapy is part of the established standard of care in cancer treatment; neoadjuvant application of immunotherapy, however, is only performed within recent trials. Combination of programmed cell death protein 1 and cytotoxic T lymphocyte antigen 4 blockade shows promising results with high pathologic response rates in the neoadjuvant setting and a very low relapse rate in the responding patients. In addition, neoadjuvant administration allows direct determination of treatment efficacy within the individual patient, and offers easy access to paired tumor material, both pretherapy and post-therapy, thus facilitates the rational development of new combinations driven by preclinical analyses. Patient-derived human tumor explant systems such as a recently developed human patient-derived tumor fragment platform can provide an additional tool to further rationalize the development of new treatment combinations. We will discuss neoadjuvant immunotherapy as a unique opportunity for rational trial design, the development of immune signatures for non-responding patients to steer clinical trial development, and the use of patient-derived ex vivo models to identify new personalized immunotherapy combinations. In this context, we propose the 'Lombard Street Approach', a back and forth approach of characterizing non-responders on neoadjuvant immunotherapy combinations, identifying promising new combinations for this group in the tumor fragment platform, and performing subsequently signature-driven small proof-of-concept combination trials. Repeating this approach with smaller and smaller groups of non-responders will step by step increase the percentage of patients benefiting from neoadjuvant immunotherapy in a rational and fast manner.

"To Anticipate": Neoadjuvant Therapy in Melanoma with a Focus on Predictive Biomarkers

Despite surgical resection and adjuvant therapies, stage III melanomas still have a substantial risk of relapse. Neoadjuvant therapy is an emerging strategy that might offer superior efficacy compared to adjuvant therapy. Moreover, neoadjuvant therapy has some virtual advantages: it might allow for less demolitive surgery, permit the in vivo evaluation of drug efficacy, help tailor adjuvant treatments, and play a crucial role in innovative translational research. Herein, we review the available literature to explore the scientific background behind the neoadjuvant approach. We also discuss published clinical trials with a focus on predictive biomarkers and ongoing studies. Finally, we outline a possible framework for future neoadjuvant clinical trial development based on the International Neoadjuvant Melanoma Consortium guidelines.

Learning from clinical trials of neoadjuvant checkpoint blockade

Neoadjuvant checkpoint inhibition, in which the therapy is administered before surgery, is a promising new approach to managing bulky but resectable melanoma, and is also being explored in other cancers. This strategy has a high pathologic response rate, which correlates with survival outcomes. The fact that biopsies are routinely available provides a unique opportunity for understanding the responses to therapy and carrying out reverse translation in which these data are used to select therapies in the clinic or in trials that are more likely to improve patient outcomes. In this Perspective, we discuss the rationale for neoadjuvant immunotherapy in resectable solid tumors based on preclinical and human translational data, summarize the results of recent clinical trials and ongoing research, and focus on future directions for enhancing reverse translation.

Neoadjuvant versus adjuvant ipilimumab plus nivolumab in macroscopic stage III melanoma

Adjuvant ipilimumab (anti-CTLA-4) and nivolumab (anti-PD-1) both improve relapse-free survival of stage III melanoma patients^1,2. In stage IV disease, the combination of ipilimumab + nivolumab is superior to ipilimumab alone and also appears to be more effective than nivolumab monotherapy³. Preclinical work suggests that neoadjuvant application of checkpoint inhibitors may be superior to adjuvant therapy⁴. To address this question and to test feasibility, 20 patients with palpable stage III melanoma were 1:1 randomized to receive ipilimumab 3 mg kg^-1 and nivolumab 1 mg kg^-1, as either four courses after surgery (adjuvant arm) or two courses before surgery and two courses postsurgery (neoadjuvant arm). Neoadjuvant therapy was feasible, with all patients undergoing surgery at the preplanned time point. However in both arms, 9/10 patients experienced one or more grade 3/4 adverse events. Pathological responses were achieved in 7/9 (78%) patients treated in the neoadjuvant arm. None of these patients have relapsed so far (median follow-up, 25.6 months). We found that neoadjuvant ipilimumab + nivolumab expand more tumor-resident T cell clones than adjuvant application. While neoadjuvant therapy appears promising, with the current regimen it induced high toxicity rates; therefore, it needs further investigation to preserve efficacy but reduce toxicity.

Combination of targeted therapy and immunotherapy in melanoma

The treatment of human melanoma has progressed markedly in recent years. Building on the observation that immune recognition is a frequent event in melanoma, a series of immunotherapeutic approaches have been evaluated in clinical trials, culminating in the first phase III study improving overall survival of melanoma patients since 20 years. However, the response rates seen upon immunotherapeutic interventions such as anti-CTLA4 treatment are often low. Furthermore, clinical responses can take several weeks to develop, during which time stage IV melanoma patients often deteriorate. Recent advances in our understanding of the genetic lesions in human melanoma now also allow the specific targeting of the signaling pathway alterations in this disease. Such targeted therapies can lead to high response rates, although the duration of these responses is thus far relatively short. We suggest that the combination of immuno and targeted therapy offers potential for synergy for both conceptual and practical reasons. In this review, we will discuss the potential and possible limitations for such combination therapy, and we describe the most promising combinations of targeted therapy and immunotherapy that can be tested in the clinic in the coming years. The concept of induction therapy by small molecule administration and consolidation by immunotherapeutics also has potential for the treatment of other human cancers.

Cytokine levels in whole blood cell cultures as parameters of the cellular immunologic activity in patients with malignant melanoma and basal cell carcinoma

For the determination of cellular immunity status, mitogen-induced lymphocyte proliferation tests are used, along with measurements of cytokine secretion. The authors have established a test system with whole blood cell cultures in which they measured the following cytokines: alpha-interleukin-1 (alpha-IL-1), interleukin-2 (IL-2), gamma-interferon (tau-IFN), and alpha-tumor necrosis factor (alpha-TNF) in the supernatants by enzymoimmunologic methods. With this system, the authors tested blood samples of 72 patients with malignant melanoma, 38 patients with basal cell carcinoma, and 315 healthy control subjects. In the blood cell cultures of the patients with melanoma, significantly lower values of the lymphokines tau-IFN and IL-2 were found, compared with those of the control subjects, and the levels of the monokines alpha-IL-1 and alpha-TNF were reduced. tau-IFN values correlated with different clinical stages. In contrast, the patients with basal cell carcinoma had equal values for all four cytokines as an age-matched control group.

Monitoring of effects induced by recombinant equine interferon-beta 1 in whole blood and separated fractions of peripheral blood of horses

Interferon is known to induce antiviral mechanisms and to exert immunoregulatory capacities on various cell types. The antiviral capacity of recombinant equine interferon-beta 1 (rEqIFN-beta 1) is most sensitively monitored by indirect quantitation of multiplication of vesicular stomatitis virus (VSV) in blood cells of horses. As few as 0.5 pg rEqIFN-beta 1/ml can be assessed by means of 90% reduction of VSV-replication in whole blood (w.b.) as well as in isolated mononuclear blood cells (MNC) in spite of individual variations. The immunoregulatory influence of 20-50 pg rEqIFN-beta 1/ml is sufficient to cause at least a 50% reduction of mitogen-induced lymphocyte proliferation in MNC, while higher concentrations are needed in w.b. Of the mitogens tested the best stimulation of proliferation on the equine lymphoid cells was obtained with staphylococcal enterotoxin B (SEB). Release of reactive oxygen species (ROS) from phagocytic cells in w.b. or from isolated polymorphonuclear cells (PMN) as monitored by chemiluminescence (CL) does not seem suitable for evaluation of rEqIFN-beta 1-induced immunoregulation as only very high rEqIFN-beta 1-concentrations (10(3)-10(4) pg/ml) result in a minute increase (up to 20%) of CL. Comparative studies on w.b. and isolated leukocyte fractions from identical specimens of individual horses suggest that monitoring of antiviral and distinct immunoregulatory capacities of rEqIFN-beta 1 can be performed on w.b. without loss of information and sensitivity as compared to isolated MNC.

A whole-blood lymphoproliferation assay for measuring cellular immunity against herpes viruses

A whole blood test system was established to study cell-mediated immunity to cytomegalovirus (CMV) and herpes simplex virus (HSV) in a large number of healthy blood donors. Cellular immunity was measured by the in vitro proliferative response (LP) of peripheral lymphocytes. These responded vigorously to several mitogens. Lymphocytes of most individuals responded to HSV, but only a limited number were reactive towards CMV. In parallel, antibodies against CMV and HSV were measured by an ELISA technique. For HSV, good correlation was observed between serological and lymphocyte proliferation results. For CMV, no clear correlation was obtained, only 21 of 40 donors positive in the antibody test being positive in the LP test. The majority of seronegatives were negative in the LP test. Use of virions purified by sucrose gradient centrifugation, or an additional strain of CMV (strain Davis) did not increase the number of donors positive in the LP test. One explanation might be that individuals possessing antibodies against CMV as measured by ELISA but no capacity to react in the LP test had suffered from a CMV infection a long time before, and now showed waning cellular immunity, but antibody still detectable. Use of the whole blood technique on 108 individuals showed that this very simple test works well with various mitogens and at least some antigens.

Prolonged BCG treatment of melanoma: does it suppress the immune capacity?

The immunological status of seven patients with disseminated melanoma during BCG scarification was followed. As parameters, the total peripheral blood leukocyte and lymphocyte counts, serum immunoglobulin levels, natural ABO blood group antibodies, lymphocyte responses in vitro to PHA and PPD, and skin reactivity against PPD and candidin were followed during a period of 2--36 months. The EAC-rosette-forming cells increased and the E-rosette-forming cells decreased during prolonged BCG therapy. The skin reactions and lymphocyte responses showed in most patients conversion from negative to positive or augmentation at the start of the therapy. Later on, however, the values in most patients dropped before disseminated disease became clinically apparent. In the only surviving patient the values first increased, remained high, and after 100 weeks treatment decreased. After 140 weeks' treatment immunological parameters are similar to pre-treatment levels. The possibility that prolonged intensive BCG treatment might eventually suppress the immune system, and thus result in an enhanced risk of dissemination of the disease, is discussed.

Immunotherapy of melanoma

Malignant melanoma is a disease characterized by clinical evidence of host defense, possibly immunologically mediated. It is a disease which tends to be refractory to both radiotherapy and chemotherapy. Immunotherapy has been used in three phases of the disease. 1. Intralesional immunotherapy with a nonspecific immune adjuvant in patients with local intradermal or soft tissue recurrence. This treatment produces approximately 15% regression of both injected and uninjected lesions, and about 60% regression of injected lesions only. Both clinical and laboratory evidence suggests that this regression is immunologically mediated. 2. Patients with surgical removal of all clinically demonstrable tumor, either primary disease alone or regional node recurrence, active nonspecific, and specific, immunotherapy has been used in an adjuvant setting. There is considerable controversy about the benefits accruing to such immunotherapy, but most large scale prospective and randomized studies have suggested that if benefit does result it is modest in degree and probably cannot be measured in terms of increase in cure rate. 3. Immunotherapy has also been used as a nonspecific active adjuvant to single drug or polychemotherapy in patients with disseminated melanoma. Whereas complete response rate may be slightly increased by this maneuver there is no convincing evidence that immunotherapy markedly increases the total objective response rate to polychemotherapy, and survival is only marginally superior when immunotherapy is added to chemotherapy in this setting. Further studies need to be done with active specific immunotherapy with tumor cell membrane extracts; as an adjuvant in patients with minimal body burden of tumor cells; and to study the inaction between chemotherapy and immunotherapy in this disease. Furthermore, studies of chemically defined fractions of either bacterial cell wall or tumor cell extracts must be evaluated both in terms of their ability to augment cell mediated immune responses in the melanoma patient, and also in terms of their ability to induce objective benefit for the patient. The possible use of immunotherapy in patients with primary melanoma has been briefly explored but needs further study. Possible additive effects with radiotherapy and immunotherapy should also be looked at in this disease utilizing high dose fractions and other new forms of radiotherapeutic technique.

Effects of repeated Corynebacterium parvum and BCG therapy on immune parameters: a weekly study of melanoma patients II. Changes in serum immunoglobulins and lymphoid cell subpopulations

Two groups, each of eight patients, with metastatic melanoma were immunized with either C. parvum or BCG at 3-weekly intervals. The serum IgG, IgA, IgM levels, E-rosettes, EA-rosetts, sIg-bearing cells, 'null cells' and lymphocyte blastogenesis at four PHA concentrations were assayed, before immunization and weekly thereafter for 8 weeks. The pre-immunization E-rosette values were significantly reduced, with a significant increase in 'null cell' values and EA-rosette percentages, when compared with healthy controls. Following C. parvum immunization, significant increases occurred in E-rosette percentages with decreases in EA-rosette and 'null cell' counts. A significant reduction in 'null cell' values also occurred with BCG. Other parameters including PHA blastogenesis did not exhibit statistically significant changes. Different methods of expressing the results (particularly of blastogenesis data) were compared, as were the similarities between the present investigation and a study of the effects of a single immunization. The relationship between the subpopulation changes and lymphocyte cytotoxicity described in an earlier article (Thatcher, Swindell & Crowther, 1979a) is discussed.

A prospective study of immune responsiveness in human melanoma. I. Assessment of initial pretreatment status with stage of disease

The clinical findings in 262 patients with melanoma were correlated with an assessment of their cellular-mediated immunity by delayed-type hypersensitivity (DTH) skin tests, by lymphocyte blastogenesis, and by leukocyte enumerations. Patients with systemic metastases (stage IV) and those with evidence of tumor burden had fewer positive DTH reactions for recall antigens than did patients with localized disease (stage I), patients with no evidence of tumor burden, and 227 normal controls. However, no differences were found in the magnitude of response among patients with melanoma or when compared with controls. Patients with melanoma had fewer responses to dinitrochlorobenzene (40% than did controls (98%), but there were no differences by stage or tumor burden. Similarly, blastogenesis in the presence of PHA, Con A, and PWM was depressed when compared with controls, but there was no meaningful correlation with the clinical status. Leukocyte, T cell, or B cell counts revealed no alteration from normal for the patients with melanoma. The usefulness of these studies for routine clinical monitoring is questioned.

Lymphocyte function related to survival curves in patients with metastatic melanoma treated by chemoimmunotherapy

Thirty-eight patients with metastatic melanoma were evaluated immunologically prior to chemoimmunotherapy. The assays used included recall antigen skin hypersensitivity; lymphocyte count; nonspecific T, non-T, and K cell lymphocytotoxicity; and T and B cell rosette enumeration. Survival curves were computed for each of four ranges of values of a given immunologic test. The higher ranges of positive skin tests, lymphocyte count, cytotoxicity, and T and B subpopulation numbers were consistently associated with the longer survivals. The differences reached statistical significance for non-T cell cytotoxicity and B and T cell peripheral blood counts. Pretreatment immune reactivity, particularly that involvingg non-T cell function, appears related to length of survival.

Recurrent malignant melanoma: effect of adjuvant immunotherapy on survival

Twenty-nine patients referred consecutively to a cancer clinic because of recurrent metastatic malignant melanoma were given 5 mg of Connaught Laboratories bacillus Calmette-Guérin (BCG) by multiple cutaneous puncture at weekly and later at monthly intervals. Eight were also treated with autologous tumour vaccine and three with intralesional BCG. This group was compared with a retrospective control group of 54 patients treated with surgery and radiotherapy alone after recurrence. Prognostic features such as site of primary and of first metastasis, disease-free interval, age and sex were similar in the two groups. However, the median survival from the time of first recurrence was 12 months in the control group but 21 months in the BCG-treated group. The major improvement was in patients with disease limited to the regional lymph nodes: the median survival was 16 months in the control group but over 32 months in the BCG-treated group. Autologous tumour vaccine appeared to have no effect on survival. Serial testing of immunocompetence did not offer any prognostic advantage, although the results of some tests correleated well with extent of disease.

Evaluation of the immunocompetance of patients with transitional cell carcinoma of the bladder

The cellular immunocompetence was examined by means of the quantitative DNCB hypersensitivity reaction in 152 patients with transitional cell carcinomas of the bladder of Broders grades 1-4. Against a control group of 367 normal controls of both sexes, 85 patients with transitional cell carcinomas of grades 1 and 2 showed a normal DNCB reactivity, irrespective of the frequency of tumour recurrence. In 9 patients of this group, an increase of malignancy from grade 2 to grade 3 was observed; the simultaneous deterioration of immunocompetence, however, was not statistically significant. On the other hand, with transitional cell carcinomas of grades 3 and 4, significant impairment of immunocompetence correlating with the tumour stage was noted.